CN118004145A

CN118004145A - Engine start control method and device, vehicle and storage medium

Info

Publication number: CN118004145A
Application number: CN202410108764.6A
Authority: CN
Inventors: 何子安; 苏钊
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2024-01-25
Filing date: 2024-01-25
Publication date: 2024-05-10

Abstract

The application provides a control method, a device, a vehicle and a storage medium for starting an engine, wherein the method is applied to the field of vehicles and comprises the following steps: acquiring a target gear of a vehicle; under the condition that the current actual driving mode of the vehicle is a pure four-wheel drive mode and the target driving mode is a direct four-wheel drive mode, if the condition that the preset condition of starting the engine is met is detected, determining a target clutch according to the target gear; when the target gear is 1 gear or 3 gears, the target clutch is a first clutch, and when the target gear is 2 gears or 4 gears, the target clutch is a second clutch; and controlling the target clutch to enter a slip state so as to start the engine. According to the method, when the vehicle needs to be switched from the pure four-wheel drive mode to the direct four-wheel drive mode, the vehicle can still be kept in four-wheel drive driving in the process of controlling the starting of the engine, and the ride-through performance and the dynamic performance of the vehicle are not affected.

Description

Engine start control method and device, vehicle and storage medium

Technical Field

The present application relates to the field of vehicles, and more particularly, to a control method of engine start in the field of vehicles, a device, a vehicle, and a storage medium.

Background

With advances in technology and advances in automotive electronics, four-wheel drive hybrid vehicles are often configured with multiple power modes to accommodate different driving demands. With development of new energy products in the passenger car market, the transmission architecture is various, and has a P0 architecture, a P1 architecture, a P2 architecture and the like optimized based on the traditional transmission, and also has a P1+P3 architecture.

Under the P1+P3 architecture, the front axle is provided with two motors, namely a GM Motor (G is denoted as a Generator, M is denoted as a Motor) and a TM Motor (Torque Max Motor, i.e. a driving Motor), which are motors with a power generation function, and the GM Motor has at least a power generation mode. The rear axle is provided with a P4 motor. Under the P1+P3 architecture, if the vehicle runs in a pure four-wheel drive mode, the front axle even shaft is hung in 2 or 4 gears, and the vehicle is driven by a TM motor of the front axle and a P4 motor of the rear axle. If the vehicle needs to start the engine in the pure four-wheel drive mode, 2-gear or 4-gear shift is required to be executed, the GM motor of the front axle is controlled to start, the engine is towed after the GM motor is started, the vehicle enters the series mode first, and then the vehicle is switched from the series mode to the direct drive mode. That is, under the p1+p3 architecture, if the vehicle is to travel in the pure four-wheel drive mode, the front axle even axle is engaged in the 2 nd gear or the 4 th gear, and if the engine is to be started, the steps of gear removal, dragging and series direct drive are required to be executed, resulting in slow switching speed. And if the step of gear shifting is executed, the vehicle is changed from the pure four-wheel drive mode to the pure two-wheel drive mode, and thus the ride-through performance and the dynamic property are easily deteriorated.

Disclosure of Invention

The application provides a control method, a device, a vehicle and a storage medium for engine starting, wherein the method can realize that the vehicle still keeps running in a four-wheel drive mode in the process of controlling the engine starting when the vehicle needs to be switched from a pure four-wheel drive mode to a direct four-wheel drive mode, and ensure that the ride-through performance and the dynamic performance of the vehicle are not affected.

In a first aspect, a control method for starting an engine is provided, and the control method is applied to a vehicle control unit of a vehicle, wherein the vehicle comprises a hybrid transmission, and the hybrid transmission comprises: the control method comprises the following steps of: acquiring a target gear of a vehicle; under the condition that the current actual driving mode of the vehicle is a pure four-wheel drive mode and the target driving mode is a direct four-wheel drive mode, if the condition that the preset condition of starting an engine is met is detected, determining a target clutch according to the target gear; wherein, when the target gear is 1 gear or 3 gears, the target clutch is the first clutch, when the target gear is 2 gear or 4 gear, the target clutch is the second clutch, in the pure four-wheel drive mode, the front drive motor and the rear drive motor of the vehicle are in a driving state, the engine is in a flameout state, in the direct four-wheel drive mode, the rear drive motor and the engine are in a driving state, the rear drive motor is used for driving rear wheels, and the engine is used for driving front wheels; and controlling the target clutch to enter a slip state so as to start the engine.

In the above technical scheme, the hybrid transmission of the vehicle includes a first input shaft and a second input shaft, the first input shaft is connected with a first clutch, and the second input shaft is connected with a second clutch. Under the above-mentioned hybrid architecture, if the current actual driving mode of the vehicle is the pure four-wheel drive mode and the target driving mode is the direct four-wheel drive mode, and the preset condition meeting the engine start is detected, then the target clutch is determined according to the target gear of the vehicle, the target clutch is controlled to enter a skid-ground state to start the engine, and the steps of gear picking, dragging and series cut and direct drive are not required to be executed, so that the starting speed of the engine is improved, and the situation that the vehicle is changed into a two-wheel drive mode from the four-wheel drive mode due to the fact that the gear picking is not carried out can be avoided, the vehicle still maintains the four-wheel drive in the starting process of the engine when the vehicle is required to be switched from the pure four-wheel drive mode to the direct four-wheel drive mode, and the ride-through performance and the power performance of the vehicle are not influenced is ensured.

With reference to the first aspect, in some possible implementations, before the controlling the target clutch to enter the slip state to start the engine, the method further includes: the target clutch is pre-filled with oil so that two clutch plates of the target clutch are engaged and the two clutch plates do not transmit torque.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, the controlling the target clutch to enter a slip state to start the engine includes: controlling the target clutch to enter a torque control mode, and determining a calibration torque value of the target clutch according to a preset engine speed and the temperature of cooling liquid of the engine; controlling the target clutch to work according to the calibrated torque value, so that the target clutch enters a slip state; when the actual rotation speed of the engine is detected to reach a rotation speed threshold value corresponding to the temperature of the cooling liquid of the engine, fuel injection control is carried out on the engine, and the engine is controlled to work according to the preset engine torque so as to start the engine.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, after the controlling the target clutch to enter the torque control mode, the method further includes: the precursor motor is controlled to increase the output torque to compensate for the wheel torque of the vehicle.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, before performing fuel injection control on the engine, the method further includes: sending an engine start preparation request to the EMS to enable the EMS to control the fuel pump to work so as to establish the oil pressure; the fuel injection control for the engine includes: an engine start request is sent to the EMS to cause the EMS to perform fuel injection control on the engine.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, the controlling the target clutch to enter a torque control mode, determining a calibration torque value of the target clutch according to a preset engine speed and a coolant temperature of the engine includes: controlling the target clutch to enter a torque control mode, and increasing the maximum torque limit value of the target clutch from 0 to the maximum torque value of the target clutch according to a preset speed; when the maximum torque limit value of the target clutch is increased to be larger than a preset torque value, determining a calibrated torque value of the target clutch according to a preset engine speed and the temperature of cooling liquid of the engine; wherein the preset torque value is smaller than the maximum torque value.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, after the engine is started, the method further includes: determining a target rotating speed matched with the current speed of the vehicle, and controlling the engine to operate according to the target rotating speed; after the actual rotation speed of the engine is successfully matched with the current vehicle speed, the control of the target clutch is exited so that the TCU controls the target clutch according to the target gear.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, after the engine is started, before the determining a target rotation speed that matches a current vehicle speed of the vehicle and controlling the engine to operate according to the target rotation speed, the method further includes: and controlling the target clutch to be disconnected.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, the controlling the opening of the target clutch includes: and controlling the actual torque value of the target clutch to be reduced to 0, and controlling the target clutch to be disconnected when the actual torque value of the target clutch is reduced to 0.

With reference to the first aspect and the foregoing implementation manner, in some possible implementation manners, when the controlling the actual torque value of the target clutch decreases to 0, the method further includes: the precursor motor of the vehicle is controlled to reduce the output torque.

In a second aspect, there is provided a control apparatus for engine start, which is provided in a hybrid vehicle including a hybrid transmission including: first input shaft and second input shaft, first input shaft is the hollow shaft, and the second input shaft runs through first input shaft setting, and first input shaft is connected with first clutch, and the second input shaft is connected with the second clutch, and above-mentioned controlling means includes: the acquisition module is used for acquiring a target gear of the vehicle; the determining module is used for determining a target clutch according to the target gear if the preset condition for starting the engine is detected to be met under the condition that the current actual driving mode of the vehicle is a pure four-wheel drive mode and the target driving mode is a direct four-wheel drive mode; wherein, when the target gear is 1 gear or 3 gears, the target clutch is the first clutch, when the target gear is 2 gear or 4 gear, the target clutch is the second clutch, in the pure four-wheel drive mode, the front drive motor and the rear drive motor of the vehicle are in a driving state, the engine is in a flameout state, in the direct four-wheel drive mode, the rear drive motor and the engine are in a driving state, the rear drive motor is used for driving rear wheels, and the engine is used for driving front wheels; and the control module is used for controlling the target clutch to enter a slip state so as to start the engine.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the foregoing control apparatus further includes: and the oil pre-filling module is used for pre-filling oil to the target clutch before the target clutch is controlled to enter a slipping state to start the engine, so that two clutch plates of the target clutch are attached and the two clutch plates do not transmit torque.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the control module is configured to control the target clutch to enter a torque control mode, and determine a calibrated torque value of the target clutch according to a preset engine speed and a coolant temperature of the engine; controlling the target clutch to work according to the calibrated torque value, so that the target clutch enters a slip state; when the actual rotation speed of the engine is detected to reach a rotation speed threshold value corresponding to the temperature of the cooling liquid of the engine, fuel injection control is carried out on the engine, and the engine is controlled to work according to the preset engine torque so as to start the engine.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the control device further includes a torque compensation module, configured to control the precursor motor to increase the output torque so as to compensate for a wheel torque of the vehicle.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the foregoing control apparatus further includes: the sending module is used for sending an engine start preparation request to the EMS before fuel injection control is carried out on the engine so that the EMS controls the fuel pump to work to establish the oil pressure; the control module performs fuel injection control on the engine, and includes: an engine start request is sent to the EMS to cause the EMS to perform fuel injection control on the engine.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the controlling module controls the target clutch to enter a torque control mode, and determines a calibrated torque value of the target clutch according to a preset engine speed and a coolant temperature of the engine, where the determining includes: controlling the target clutch to enter a torque control mode, and increasing the maximum torque limit value of the target clutch from 0 to the maximum torque value of the target clutch according to a preset speed; when the maximum torque limit value of the target clutch is increased to be larger than a preset torque value, determining a calibrated torque value of the target clutch according to a preset engine speed and the temperature of cooling liquid of the engine; wherein the preset torque value is smaller than the maximum torque value.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the foregoing control apparatus further includes: the exit module is used for determining a target rotating speed matched with the current speed of the vehicle after the engine is started and controlling the engine to run according to the target rotating speed; after the actual rotation speed of the engine is successfully matched with the current vehicle speed, the control of the target clutch is exited so that the TCU controls the target clutch according to the target gear.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the foregoing control apparatus further includes: and the clutch control module is used for determining a target rotating speed matched with the current speed of the vehicle after the engine is started and controlling the target clutch to be disconnected before the engine is controlled to run according to the target rotating speed.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the clutch control module is specifically configured to control the actual torque value of the target clutch to decrease to 0, and control the target clutch to be disconnected in a case where the actual torque value of the target clutch decreases to 0.

With reference to the second aspect and the foregoing implementation manner, in some possible implementation manners, the foregoing control apparatus further includes: and a motor torque control module for controlling a motor precursor of the vehicle to reduce the output torque when the actual torque value of the target clutch is controlled to be reduced to 0.

In a third aspect, a vehicle is provided that includes a memory for storing executable program code; and a processor for calling and running the executable program code from the memory to cause the vehicle to execute the engine start control method.

In a fourth aspect, there is provided a computer program product comprising: computer program code which, when run on a computer, causes the computer to perform the method of the first aspect or any one of the possible implementations of the first aspect.

In a fifth aspect, a computer readable storage medium is provided, the computer readable storage medium storing computer program code which, when run on a computer, causes the computer to perform the method of the first aspect or any one of the possible implementations of the first aspect.

Drawings

FIG. 1 is a schematic plan view of a hybrid transmission according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a power route with gear 2 in a pure four-wheel drive mode according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a power route with a gear of 4 in a pure four-wheel drive mode according to an embodiment of the present application;

fig. 4 is a schematic diagram of a power route with a gear of 1 in a direct-drive four-drive mode according to an embodiment of the present application;

Fig. 5 is a schematic diagram of a power route with a gear of 2 in a direct-drive four-drive mode according to an embodiment of the present application;

FIG. 6 is a schematic diagram of a power route in a series mode provided by an embodiment of the present application;

FIG. 7 is a schematic flow chart diagram of a control method for engine start provided by an embodiment of the present application;

FIG. 8a is a timing diagram of an engine start-up procedure provided by an embodiment of the present application;

FIG. 8b is a second timing diagram of an engine start-up procedure according to an embodiment of the present application;

FIG. 8c is a third timing diagram of an engine start-up procedure according to an embodiment of the present application;

fig. 9 is a schematic view of an engine starting apparatus according to an embodiment of the present application;

fig. 10 is a schematic structural view of a vehicle according to an embodiment of the present application.

Detailed Description

The technical scheme of the application will be clearly and thoroughly described below with reference to the accompanying drawings. Wherein, in the description of the embodiments of the present application, unless otherwise indicated, "/" means or, for example, a/B may represent a or B: the text "and/or" is merely an association relation describing the associated object, and indicates that three relations may exist, for example, a and/or B may indicate: the three cases where a exists alone, a and B exist together, and B exists alone, and furthermore, in the description of the embodiments of the present application, "plural" means two or more than two.

The terms "first," "second," and the like, are used below for descriptive purposes only and are not to be construed as implying or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

The embodiment of the application provides a control method for starting an engine, which is applied to a hybrid vehicle, and the vehicle can be also called a hybrid vehicle. The control units in the hybrid vehicle may include HCU (hybrid control unit ), TCU (Transmission Control Unit, automatic transmission control unit), VCU (Vehicle Control Unit, whole vehicle control unit), PDCU (Power train Domain Control Unit, new energy power domain control unit), EMS (ENGINE MANAGEMENT SYSTEM, engine controller), TMCU (Drive Motor control Unit ). The hybrid vehicle further includes a hybrid transmission, and the hybrid transmission according to the present embodiment will be described with reference to fig. 1. FIG. 1 is a schematic plan view of a hybrid transmission.

Referring to fig. 1, the hybrid transmission includes a motor shaft 23, an engine output 24, a first input shaft 28, a second input shaft 25, a mechanical pump gear set, an output shaft 26, and a differential 27. Wherein the first input shaft may also be referred to as an external transmission input shaft and the second input shaft may also be referred to as an internal transmission input shaft. The transmission outer input shaft may be referred to as an odd shaft (hereinafter also referred to as an odd shaft) and the transmission inner input shaft may be referred to as an even shaft (hereinafter also referred to as an even shaft).

In fig. 1, the transmission outer input shaft is taken as an odd-numbered shaft, and the transmission inner input shaft is taken as an even-numbered shaft. In a specific implementation, the transmission outer input shaft may also be used as an even number shaft, and the transmission inner input shaft may also be used as an odd number shaft. That is, the first input shaft may also be used as an internal transmission input shaft and the second input shaft may also be used as an external transmission input shaft.

The first clutch 18 is connected to the first input shaft 28, and a plurality of first-gear drive gears are fixedly provided in order on the first input shaft 28. The second input shaft 25 is connected with a second clutch 19, a plurality of second gear driving gears are sequentially and fixedly arranged on the second input shaft 25, and the first gear driving gear or the second gear driving gear is in transmission connection with the motor shaft 23. The output shaft 26 is in transmission connection with the differential mechanism 27, and a plurality of gear driven gears are sleeved on the output shaft 26 in sequence in a hollow mode, and are respectively meshed with the first gear driving gears and the second gear driving gears in a one-to-one correspondence mode. The mechanical pump gear set is connected to the engine output 24 through the outer hub of the second clutch 19.

The first gear driving gears at least comprise a first gear 1 and a second gear 2, the second gear driving gears at least comprise a third gear 3 and a fourth gear 4, the plurality of gear driven gears at least comprise a fifth gear 5, a sixth gear 6, a seventh gear 7 and a eighth gear 8, the fifth gear 5, the sixth gear 6, the seventh gear 7 and the eighth gear 8 are meshed with the first gear 1, the second gear 2, the third gear 3 and the fourth gear 4 in one-to-one correspondence, a first gear shifter 20 is arranged between the seventh gear 7 and the eighth gear 8, and a second gear shifter 21 is arranged between the fifth gear 5 and the sixth gear 6.

The motor gear set at the end of the motor shaft 23 comprises a motor driving gear 14 and a motor driven gear 15, the motor driving gear 14 is fixedly connected to the end of the motor input end, the motor driven gear 15 is meshed with the motor driving gear 14 and meshed with the gear two 2 to realize pure electric 1-gear and 3-gear transmission or meshed with the gear four 4 to realize pure electric 2-gear and 4-gear transmission, so that the motor shaft 23 is in transmission connection with the second input shaft 25 or the first input shaft 28, and the motor can independently provide power or the motor is matched with an engine to provide hybrid power.

Wherein, one end of the output shaft 26 is fixedly provided with a parking gear 16, and the other end of the output shaft 26 is fixedly provided with a gear nine 9 for engaging a differential 27. The differential 27 is connected with a gear ten 10 meshed with the gear nine 9, so that the output shaft 26 is in transmission fit with the differential 27.

The mechanical pump gear set comprises a mechanical pump driving gear and a mechanical pump driven gear, wherein the mechanical pump driving gear is directly connected with an outer hub of the second clutch 19, the outer hub of the second clutch 19 is in transmission connection with the engine output end 24, the mechanical pump driving gear is meshed with the mechanical pump driven gear, and the mechanical pump driven gear is in transmission connection with the mechanical pump.

The four-wheel drive mode, the direct-drive four-wheel drive mode, and the series mode involved in this implementation are described below in connection with the hybrid transmission of fig. 1:

In the four-wheel drive mode, the front and rear drive motors of the vehicle are in a driving state, and the engine is in a flameout state. A battery pack in the vehicle supplies power to both the front-drive motor and the rear-drive motor such that the front-drive motor drives the front wheels of the vehicle to rotate and the rear-drive motor drives the rear wheels of the vehicle to rotate. The front drive motor is disposed at a front axle position of the vehicle and thus may be referred to as a front axle motor, and the rear drive motor is disposed at a rear axle position of the vehicle and thus may be referred to as a rear axle motor.

To facilitate an understanding of the flow direction of the power transfer in the four-wheel drive mode, further description is provided below in conjunction with fig. 2 and 3:

Fig. 2 is a schematic diagram of a power route with gear 2 in the four-wheel drive mode. As can be seen from fig. 2, the power route for the gear 2 in the pure four-wheel drive mode is: the front wheel comprises a front drive motor, a motor shaft 23, a motor driving gear 14, a motor driven gear 15, a gear IV 4, a gear III 3, a gear seven 7, a first gear shifter 20, a gear nine 9, a gear ten 10, a differential 27 and front wheels.

Fig. 3 is a schematic diagram of the power route with gear 4 in the four-wheel drive mode. As can be seen from fig. 3, the power route for the gear 4 in the pure four-wheel drive mode is: the front wheel comprises a front motor, a motor shaft 23, a motor driving gear 14, a motor driven gear 15, a gear IV 4, a gear eight 8, a first gear shifter 20, a gear nine 9, a gear ten 10, a differential 27 and front wheels.

In the direct-drive four-wheel drive mode, both the rear-drive motor and the engine are in a driving state, the rear-drive motor is used for driving rear wheels, and the engine is used for driving front wheels. The state of the precursor motor is related to the current vehicle speed, and the following description is made respectively:

In the direct-drive four-wheel drive mode, if the current speed is less than or equal to the creep speed, the precursor motor is in a non-working state. The non-operating state is understood to be a 0 torque state, i.e. the precursor motor does not output torque, in which the precursor motor is not involved in driving the front wheels, nor is it charged the battery pack.

In the direct-drive four-wheel drive mode, if the current speed is greater than the creep speed, the precursor motor is in a power generation state or a driving state. When the precursor motor is in a power generation state, the precursor motor is used for charging the battery pack. When the front drive motor is in a driving state, the engine and the front drive motor are used for jointly driving the front wheels.

Specifically, the output torque of the engine may be compared with the required torque of the front wheels to determine whether the front-drive motor is in a generating state or a driving state.

If the output torque of the engine is greater than the required torque of the front wheels, the output torque of the engine can meet the required torque of the front wheels and redundant torque exists. At this time, the output torque of the engine may be divided into a driving torque, which is equal to the required torque of the front wheels, and a charging torque, which is used to drive the front wheels. The charging torque is equal to the torque difference between the output torque of the engine and the driving torque, i.e., the above-described surplus torque, and is used to be supplied to the precursor motor so that the battery pack can be charged by the precursor motor. At this time, the precursor motor is in a power generation state.

If the output torque of the engine is smaller than the required torque of the front wheels, the output torque of the engine is not capable of meeting the required torque of the front wheels, and the front motor is required to assist. At this time, a torque difference between the required torque of the front wheels and the output torque of the engine may be determined as the assist torque of the precursor motor so that the precursor motor drives the front wheels together with the engine by outputting the assist torque. At this time, the precursor motor is in a driving state.

If the output torque of the engine is equal to the required torque of the front wheels, the output torque of the engine is indicated to just meet the required torque of the front wheels. At this time, the precursor motor does not need to assist or generate power, i.e., the precursor motor can be in a non-operating state.

To facilitate an understanding of the flow direction of the power transmission in the direct-drive four-wheel drive mode, further description is provided below with reference to fig. 4 and 5:

Fig. 4 is a schematic diagram of a power route with a gear 1 in a direct drive four-wheel drive mode. As can be seen from fig. 4, the power route of the gear 1 in the direct-drive four-wheel-drive mode is as follows: the engine output 24- > the first clutch 18- > the first input shaft 28- > gear one 1- > gear five 5- > the second shifter 21- > gear nine 9- > gear ten 10- > the differential 27- > the front wheels.

Fig. 5 is a schematic diagram of a power route with gear 2 in the direct-drive four-drive mode. As can be seen from fig. 5, the power route of the gear 2 in the direct-drive four-wheel-drive mode is as follows: the engine output 24- & gtthe second clutch 19- & gtthe second input shaft 25- & gtthe third gear 3- & gtthe seventh gear 7- & gtthe first shifter 20- & gtthe ninth gear 9- & gtthe tenth gear 10- & gtthe differential 27- & gtthe front wheels.

When the gear is 3 in the direct-drive four-wheel drive mode, the corresponding power route is as follows: the engine output 24- & gtthe first clutch 18- & gtthe first input shaft 28- & gtthe second gear 2- & gtthe sixth gear 6- & gtthe second gear shifter 21- & gtthe ninth gear 9- & gtthe tenth gear 10- & gtthe differential 27- & gtthe front wheels.

When the gear is 4 in the direct-drive four-wheel drive mode, the corresponding power route is as follows: the engine output 24- & gtthe second clutch 19- & gtthe second input shaft 25- & gtthe fourth gear 4- & gtthe eighth gear 8- & gtthe first shifter 20- & gtthe ninth gear 9- & gtthe tenth gear 10- & gtthe differential 27- & gtthe front wheels.

It should be noted that, the power route corresponding to the 4 gears in the direct-drive four-drive mode is substantially a power route in which the output torque of the engine is distributed to the front wheels to drive the front wheels. When the front drive motor is in a driving state, the front drive motor is used for assisting the driving of the front wheels, namely, the front drive motor and the engine drive the front wheels together. When the front drive motor is in a power generation state, the front drive motor does not participate in driving of the front wheels, and the engine independently drives the front wheels. When the front drive motor is in a non-working state, the front drive motor does not participate in driving of the front wheels and does not participate in power generation, and the engine independently drives the front wheels.

The states of the first clutch 18 and the second clutch 19 in the direct-drive four-drive mode are described below. If the current vehicle speed is less than or equal to the creep vehicle speed, the first clutch 18 is in a slipping state and the second clutch 19 is in a disengaged state. If the current vehicle speed is greater than the creep vehicle speed, the first clutch 18 or the second clutch 19 is in a closed state. Specifically, as can be seen from the power line of the 4 gears in the direct-drive four-drive mode, the first clutch 18 is in a closed state and the second clutch 19 is in an open state in the 1-gear and 3-gear in the direct-drive four-drive mode, so that the output torque of the engine can be transmitted to the front wheels through the first clutch 18. In the direct drive four-drive mode, 2 nd and 4 th gears, the second clutch 19 is in a closed state, and the first clutch 18 is in an open state, so that the output torque of the engine can be transmitted to the front wheels through the second clutch 19.

In the series mode, the engine drives the front drive motor to operate for generating electricity, and the rear drive motor drives the rear axle wheels. In the series mode, the engine is operated, the precursor motor is operated to generate electricity, and the electric energy generated by the precursor motor can charge the battery pack. The front axle wheels are driven, the rear drive motor operates to output power, and the rear axle wheels are driven to drive the vehicle to run. To facilitate an understanding of the flow direction of power transfer in series mode, further description is provided below in connection with FIG. 6:

FIG. 6 is a schematic diagram of a power route in series mode. As can be seen in connection with fig. 6, the power route in series mode is: the engine output 24- & gtthe second clutch 19- & gtthe second input shaft 25- & gtthe fourth gear 4- & gtthe motor driven gear 15- & gtthe motor driving gear 14- & gtthe motor shaft 23 (motor power generation). The motor shaft can be understood as the motor shaft of the precursor motor, and the motor power generation refers to the power generation of the precursor motor. In the series mode, the precursor motor acts as a GM motor.

The implementation flow of the engine start control method in the present embodiment will be specifically described with reference to fig. 1 to 6.

Fig. 7 is a schematic flowchart of a control method for engine start provided in an embodiment of the present application. The execution subject of the control method may be a control unit in the vehicle, such as the HCU or VCU or PDCU described above.

As shown in fig. 1 to 6, the front axle motor of the vehicle in the present embodiment has only one, i.e., the front motor in the drawing, which functions as a GM motor in the series mode, and functions as a TM motor in the four-wheel drive mode or the direct-drive four-wheel drive mode. Since the front-drive motor actually acts as a TM motor rather than a GM motor when the vehicle is in the four-wheel drive mode, the engine cannot be towed up after being started by the GM motor as in the p1+p3 architecture. Therefore, the present embodiment proposes a way of starting the engine by the target clutch with the precursor motor functioning as the TM motor, so that the starting of the engine can be smoothly achieved even if the precursor motor is currently functioning as the TM motor.

For example, as shown in fig. 7, the control method of engine start includes:

S101, acquiring a target gear of the vehicle.

S102, if the preset condition of starting the engine is detected to be met under the condition that the current actual driving mode of the vehicle is a pure four-wheel drive mode and the target driving mode is a direct four-wheel drive mode, determining a target clutch according to the target gear.

S103, controlling the target clutch to enter a slip state to start the engine.

In the embodiment shown in fig. 7, the vehicle includes the hybrid transmission as shown in fig. 1, if the current actual driving mode of the vehicle is the pure four-drive mode and the target driving mode is the direct four-drive mode, and the preset condition for starting the engine is detected to be met, the target clutch is determined according to the target gear of the vehicle, and the target clutch is controlled to enter the skid-ground state to start the engine, without executing the steps of gear shifting, dragging and series direct drive, so that the starting speed of the engine is improved, and the vehicle is prevented from being changed from the four-drive mode to the two-drive mode due to the fact that the gear shifting is not performed, the vehicle can still maintain the four-drive running during the starting process of the engine when the vehicle needs to be switched from the pure four-drive mode to the direct four-drive mode, and the ride-through performance and the power performance of the vehicle are ensured not to be affected.

The following describes a specific implementation of each step in the embodiment shown in fig. 7:

In S101, the target gear of the vehicle may be a gear of the vehicle in the target driving mode, which may be determined based on an actual speed of the vehicle and throttle information, which may be specifically an opening degree of the throttle pedal. Specifically, the correspondence between the vehicle speed, the opening degree of the accelerator pedal, and the gear may be pre-stored in the vehicle, so that the corresponding gear may be determined as the target gear according to the actual vehicle speed, the opening degree of the actual accelerator pedal, and the correspondence. The target gear and the target driving mode can be calculated by a driving computer according to the actual running state of the vehicle.

By way of example, assuming that the actual vehicle speed is greater than or equal to 10km/h and less than 18km/h, the target gear is 1 if the opening of the accelerator pedal is less than the preset opening threshold, and the target gear is 2 if the opening of the accelerator pedal is greater than the preset opening threshold. Assuming that the actual vehicle speed is greater than or equal to 18km/h and less than 30km/h, the target gear is 2 if the opening degree of the accelerator pedal is small, and the target gear is 1 if the opening degree of the accelerator pedal is large. Assuming that the actual vehicle speed is greater than or equal to 30km/h and less than 70km/h, the target gear may be 2 or 3 depending on the opening degree of the accelerator pedal. Assuming that the actual vehicle speed is greater than 70km/h, the target gear may be 3 rd gear or 4 th gear depending on the opening degree of the accelerator pedal.

In S102, if it is determined that the current actual driving mode of the vehicle is the four-wheel drive only mode and the target driving mode is the four-wheel drive direct drive mode, and it is detected that the preset condition for engine start is satisfied, the target clutch is determined according to the target gear. When the target gear is 1 or 3, the target clutch is a first clutch, and when the target gear is 2 or 4, the target clutch is a second clutch. In a specific implementation, when the actual gear of the even shaft is 2 or 4, it may be determined that the current actual driving mode of the vehicle is a pure four-wheel drive mode.

The preset conditions for starting the engine can be preset according to the starting conditions of the engine, so that the engine can be started when the engine needs to be started.

For example, the HCU may obtain operating condition information of the vehicle, thereby determining whether the starting condition of the engine is currently satisfied according to the operating condition information of the vehicle. The working condition information of the vehicle may include: the actual rotational speed of the TM Motor (Torque Max Motor), the actual position of the shift lever, the actual state of the engine, whether the engine start request is triggered, whether the engine inhibit start request is triggered, whether in the four-drive operation mode, and the like. The TM motor may be the precursor motor described above.

For example, the starting conditions of the engine may include, but are not limited to: the actual state of the engine is a flameout state, the actual rotation speed of the TM motor is lower than a preset rotation speed threshold value, the actual position of the gear lever is D gear, the engine start request is triggered, the engine start prohibition request is not triggered, the vehicle is in a four-wheel drive mode such as SPORT (SPORTs), AWD (All-WHEEL DRIVE, full-time four-wheel drive), SNOW (snowfield), MUD (MUD), SAND (SAND), and the like. The preset rotation speed threshold value can be set according to actual needs, for example, can be set to be 100rpm, and the fact that the actual rotation speed of the TM motor is lower than 100rpm is used as one of starting conditions of the engine, so that failure of starting the engine can be avoided.

In S103, the HCU may control the target clutch to enter a slip state to start the engine. For example, if the target gear is 1 or 3, the first clutch 18 shown in FIG. 1 may be controlled to enter a slip state to start the engine. If the target gear is 2 or 4, the second clutch 19 shown in FIG. 1 may be controlled to enter a slip state to start the engine. In the case of controlling the first clutch to enter the slipping state, the second clutch may be controlled to be disengaged. In the event that the second clutch is controlled to enter the slipping state, the first clutch 18 may be controlled to be disengaged.

In an exemplary embodiment, before the control target clutch enters the slip state to start the engine, the method further includes: the target clutch is pre-filled such that the two clutch plates of the target clutch are in engagement and the two clutch plates do not transmit torque.

Specifically, the HCU may send a target clutch torque control request to the TCU such that the TCU, upon receiving the target clutch torque control request, controls the target clutch to be pre-filled with oil such that two clutch plates of the target clutch are engaged and the two clutch plates do not transmit torque.

In this embodiment, the oil is pre-filled before the target clutch is controlled to perform the sliding state, which is favorable for pushing the two clutch plates of the target clutch to the position capable of transmitting torque in advance, so that the subsequent action of the target clutch is a little faster, which is equivalent to the advance preparation, and the subsequent quick entry into the sliding state is facilitated.

In an exemplary embodiment, the implementation of S103 may include the following S1031 to S1033:

S1031, controlling the target clutch to enter a torque control mode, and determining a calibration torque value of the target clutch according to the preset engine speed and the temperature of the cooling liquid of the engine.

It will be appreciated that since the current actual driving mode of the vehicle is the four-wheel-drive-only mode and has not yet entered the coast state, the target clutch is still in the disengaged state, i.e., the target clutch is not actually operating. If the target clutch is to be controlled to enter the slip state, it is necessary that the target clutch first enter an active state, i.e., the control target clutch needs to enter a torque control mode so that the target clutch can transmit torque. The target clutch enters a torque control mode, indicating that the TCU may respond to the HCU's torque control of the target clutch. Alternatively, the target clutch may be controlled to enter the torque control mode after being pre-filled with oil. For example, the TCU may control the target clutch to enter the torque control mode after the target clutch is filled with oil.

For example, the implementation of S1031 may include: controlling the target clutch to enter a torque control mode, and lifting the maximum torque limit value of the target clutch from 0 to the maximum torque value of the target clutch according to a preset speed; when the maximum torque limit value of the target clutch is increased to be larger than a preset torque value, determining a calibrated torque value of the target clutch according to the preset engine speed and the temperature of cooling liquid of the engine; the preset torque value is smaller than the maximum torque value.

Because the current actual driving mode of the vehicle is the pure four-wheel drive mode and the vehicle does not enter the skid state, the target clutch is still in the disconnection state at the moment, and the maximum torque limiting value of the target clutch is 0, namely the target clutch does not transmit torque at the moment. Therefore, to bring the target clutch into the slip state, the HCU may send an adjustment instruction of the maximum torque limit value of the target clutch to the TCU, so that the TCU increases the maximum torque limit value of the target clutch from 0 to the maximum torque value of the target clutch at a preset rate. Or the TCU may control the target clutch to enter a torque control mode after the target clutch is pre-filled with oil, and raise the maximum torque limit value of the target clutch from 0 to the maximum torque value of the target clutch at a preset rate. The maximum torque value of the target clutch is understood to be the maximum torque capacity of the target clutch, which belongs to the inherent parameters of the target clutch. The preset rate can be set according to actual needs, so that the maximum torque limit value of the target clutch can be gradually increased according to the expected rate. The torque capacity limit of the target clutch is adjusted to the torque capacity limit, which means that the HCU can request the target clutch to operate at the torque capacity limit according to actual needs.

In the process that the maximum torque limit value of the target clutch is lifted, if the maximum torque limit value is detected to be lifted to be larger than a preset torque value and the actual odd-axis gear is 1 or 3, the HCU determines the calibrated torque value of the target clutch according to the preset engine speed and the cooling liquid temperature of the engine. The preset engine speed may be determined empirically, such as by determining how much engine speed is capable of dragging the engine. The temperature of the coolant of the engine can be measured by a temperature sensor. The preset torque value may be, for example, 200Nm, which is smaller than the maximum torque value, which may be, for example, 320Nm.

Specifically, a preset association relationship can be provided among the engine speed, the coolant temperature of the engine and the calibration torque value of the target clutch, so that the calibration torque value of the target clutch can be obtained by combining the association relationship under the condition that the engine speed and the coolant temperature of the engine are known. For example, if the preset engine speed is < 600rpm and the coolant temperature of the engine is 0 ℃, the target clutch calibration torque value is 100Nm. If the preset engine speed is less than 900rpm and the coolant temperature of the engine is 0 ℃, the calibrated torque value of the target clutch is 20Nm. If the preset engine speed is less than 1000rpm and the coolant temperature of the engine is 0 ℃, the target clutch calibration torque value is 0Nm.

S1032, controlling the target clutch to work according to the calibrated torque value, so that the target clutch enters a slip state.

Specifically, the HCU may initiate a target clutch torque request carrying the above-mentioned calibration torque value to the TCU, and after receiving the target clutch torque request, the TCU controls the target clutch to operate according to the calibration torque value, so that the target clutch enters a slip state. The above-described calibration torque value may also be understood as a slip torque value for controlling the target clutch into a slip state. When the target clutch enters the slip state, the start-stop mode of the engine may be set to "start".

And S1033, when the actual rotation speed of the engine reaches the rotation speed threshold value corresponding to the temperature of the cooling liquid of the engine, performing fuel injection control on the engine, and controlling the engine to work according to the preset engine torque so as to start the engine.

Different cooling liquid temperatures can be corresponding to respective rotating speed thresholds, and the cooling liquid temperatures are lower and the rotating speed thresholds are larger. In this embodiment, the rotational speed threshold may be 900rpm.

It will be appreciated that when the target clutch is brought into a slip state, a portion of the torque at the wheel end is transferred to the engine, causing the engine to begin rotating, i.e., the engine begins to have a rotational speed. When it is detected that the actual rotational speed of the engine reaches a rotational speed threshold corresponding to the coolant temperature of the engine, the HCU may perform fuel injection control on the engine and control the engine to operate according to a preset engine torque to start the engine. The preset engine torque may be set according to actual needs, for example, may be 10Nm.

In this embodiment, the target clutch enters a torque control mode, representing that the TCU is able to respond to the HCU's torque control of the target clutch. The maximum torque limit value of the target clutch is increased to the maximum torque value, which represents that the HCU can request the maximum torque value of the target clutch, and when the maximum torque limit value of the target clutch is increased to be greater than the preset torque value, the target clutch has a certain torque capacity, and at the moment, the HCU requests the calibration torque value of the target clutch, so that the HCU can request the calibration torque value successfully.

In an exemplary embodiment, before the fuel injection control of the engine, the method further includes: sending an engine start preparation request to the EMS to enable the EMS to control the fuel pump to work so as to establish the oil pressure;

the fuel injection control for the engine includes: an engine start request is sent to the EMS to cause the EMS to perform fuel injection control on the engine.

Specifically, when the HCU determines that the start condition of the engine is satisfied, that is, the HCU needs to start the engine, an engine start preparation request may be sent to the EMS, so that the EMS controls the fuel pump to operate to establish the oil pressure after receiving the engine start preparation request, and the engine is put into a ready-to-operate state. When the actual rotation speed of the engine is detected to reach a rotation speed threshold corresponding to the temperature of cooling liquid of the engine, and the ignition is proper at the moment, the HCU sends an engine starting request to the EMS so that the EMS can perform fuel injection control on the engine.

In this embodiment, an engine start preparation request is sent to the EMS first, so that the EMS controls the fuel pump to operate to establish the oil pressure, so that the engine enters a state of preparation for operation, and the engine is conveniently and quickly started directly based on the engine start request at a later time.

For example, when the HCU needs to start the engine, an engine start-stop type request carrying a target start-stop type may also be sent to the EMS, so that the EMS starts the engine according to the target start-stop type carried in the engine start-stop type request. The target start-stop type can be any one of the following: initialization and no start, normal 12V idle start, normal idle start, comfort drive start, dynamic drive start, etc.

For example, after the EMS performs fuel injection control on the engine so that the engine start is successful, the HCU may reset the engine start preparation request and the engine start request to an inactive state and set the engine start stop mode to "torque transmission".

In an exemplary embodiment, after the control target clutch enters the torque control mode, the method further includes: the control motor increases the output torque to compensate for the wheel torque of the vehicle.

It will be appreciated that since the skid start is to transfer a portion of the wheel torque at the wheel end to the engine, the engine is started and the wheel torque is reduced. In order to avoid the decrease in the vehicle speed caused by the decrease in the wheel torque, in this embodiment, after the target clutch enters the torque control mode, the output torque of the precursor motor is controlled to be increased, for example, the output torque of the precursor motor and the torque of the target clutch are controlled to be synchronously increased so as to compensate the wheel torque of the vehicle, which is beneficial to avoiding the decrease in the vehicle speed caused by the decrease in the wheel torque in the process of starting the engine by slipping.

Specifically, the HCU may send a torque increase request to the motor control unit TMCU of the precursor motor, such that the TMCU, upon receiving the torque increase request, controls the precursor motor, i.e., the TM motor, to increase the output torque. Wherein the torque increase request may carry a torque set point such that the TMCU may control the output torque of the TM motor to follow the torque set point.

In an exemplary embodiment, after the engine is started, further comprising: determining a target rotating speed matched with the current speed of the vehicle, and controlling the engine to operate according to the target rotating speed; after the actual rotation speed of the engine is successfully matched with the current vehicle speed, the control of the target clutch is exited, so that the TCU controls the target clutch according to the target gear.

Since the engine may be at a higher speed than the target speed desired in the direct-drive four-drive mode after the engine is started, the engine may be at a lower speed than the target speed. Therefore, after the engine is started by the skid mill so that the vehicle enters the direct-drive four-drive mode, the engine speed can be controlled to match the current vehicle speed. The actual rotating speed of the engine is successfully matched with the current vehicle speed, namely, the actual speed difference of two ends of the target clutch is smaller than a preset speed difference threshold value, at the moment, the HCU can withdraw from the control of the target clutch, and the TCU can control according to the target gear. The preset speed difference threshold value can be set according to actual needs, for example, can be set to be 100rpm.

Specifically, the HCU may define an engine target speed profile based on vehicle speed and gear ratio to a target gear. Then, the HCU constructs a torque command according to the engine target speed curve, and sends the constructed torque command to the EMS, so that the EMS determines a target speed matched with the current speed according to the engine target speed curve, and controls the engine to run according to the target speed. It is understood that there is a corresponding conversion relationship between the vehicle speed and the engine speed of the vehicle, and the target speed that matches the current vehicle speed may be determined according to the current vehicle speed of the vehicle and the conversion relationship.

And when the actual rotating speed of the engine is detected to be equal to the target rotating speed, determining that the actual rotating speed of the engine is successfully matched with the current vehicle speed. At this point, the HCU may send a first clutch no request and a second clutch no request to the TCU to indicate that the HCU is exiting control of the first clutch and the second clutch. After the HCU exits control of the first and second clutches, the TCU may control the target clutch of the first and second clutches to close for a preset period of time and feedback to the TCU that the target clutch is already in a closed state after the actual torque of the target clutch reaches a calibrated threshold associated with the engine coolant temperature (e.g., 100Nm when the engine coolant temperature is 0 ℃).

In an exemplary embodiment, after the engine is started, determining a target rotational speed that matches a current vehicle speed of the vehicle, and before controlling the engine to operate at the target rotational speed, further comprising: the control target clutch is opened.

Specifically, the HCU may send a target clutch disconnect request to the TCU so that the TCU may control the target clutch to be disconnected.

Because, after the skid-mounted start engine enters the direct-drive four-drive mode, the engine speed is controlled to be matched with the vehicle speed in order to enable the engine to adapt to the current running state of the vehicle. If the target clutch is directly closed, the target clutch state is directly changed from the skid state to the closed state, and vehicle shake is likely to occur, so that after the skid starts the engine successfully, the target clutch is controlled to be disconnected firstly, and then the engine speed is adjusted after the disconnection so as to control the engine speed to be matched with the vehicle speed, and after the matching is successful, the TCU controls the target clutch to be closed according to the target gear, thereby being beneficial to avoiding vehicle shake.

In an exemplary embodiment, the control target clutch is opened, including: the actual torque value of the control target clutch is reduced to 0, and in the case where the actual torque value of the target clutch is reduced to 0, the control target clutch is disconnected.

Specifically, the HCU may send a target clutch torque reduction request to the TCU so that the TCU may control the actual torque value of the target clutch to be reduced to 0Nm. The HCU may send a target clutch off request to the TCU after detecting that the actual torque value of the target clutch has fallen to 0Nm so that the TCU may control the target clutch to be off.

In this embodiment, if the target clutch is disconnected when the actual torque value of the target clutch is not reduced to 0Nm, the engine speed is liable to drift up, the instantaneous torque of the wheel end fluctuates, and thus the vehicle rattles. Therefore, the actual torque value of the target clutch is reduced to 0, and then the target clutch is disconnected, so that vehicle shake is further avoided.

In an exemplary embodiment, when the actual torque value of the control target clutch is reduced to 0, further comprising: the precursor motor of the vehicle is controlled to reduce the output torque.

Specifically, when the actual torque value of the control target clutch is reduced to 0, the HCU may send a torque reduction request to the TMCU so that the TMCU may control the precursor motor to reduce the output torque. For example, the output torque of the precursor motor and the actual torque value of the target clutch may be controlled to be simultaneously reduced to eventually reduce both the output torque of the precursor motor and the actual torque value of the target clutch to 0.

In this embodiment, considering that the output torque of the precursor motor is transmitted to the target clutch, if only the torque of the target clutch is reduced, the motor torque is not reduced, and abnormal acceleration of the vehicle is easily caused, so that when the torque of the target clutch is reduced, the output torque of the precursor motor is synchronously reduced, which is beneficial to avoiding abnormal acceleration of the vehicle.

In an exemplary embodiment, after the HCU exits control of the target clutch, the TCU may control the target clutch to close according to the target gear. When the target clutch is detected to be closed, the HCU can determine the first torque distributed to the engine and the second torque distributed to the TM motor based on the torque required by the whole vehicle, control the engine to output the first torque, control the TM motor to output the second torque to jointly drive the vehicle, so that the engine can operate according to an optimal economic curve, and the economy of the whole vehicle is improved. When the target clutch is detected to be closed, the HCU can also set the engine start-stop mode to be normal operation and set the actual driving mode to be a direct-drive four-drive mode.

The following explains a control method of engine start in the embodiment of the application with reference to a specific example:

When the vehicle meets the following conditions:

1. The engine is in a flameout state, and

2. Vehicle speed is above a first calibration threshold (e.g., 10 km/h) and below a second calibration threshold (e.g., 18 km/h), and

3. The operation modes are SPORT/AWD/SNOW/MUD/SAND, and

4. The current even shaft gear is 2 gear, and

5. The gear shift lever is located at the D gear.

If it is further detected that the following condition is satisfied:

1. Triggering an engine start request without an engine start inhibit request, and

The rotational speed of the TM motor is below a third calibrated threshold (e.g., 100 rpm) to prevent engine start failure, and

3. The target gear is 1 gear, and

4. The target driving mode is a direct-drive four-drive mode.

Because, when the front even axle gear is 2 gear, the vehicle is indicated to be in the pure four-wheel drive mode. Thus, in combination with the above description, if the above 9 condition descriptions are satisfied: the current actual driving mode of the vehicle is a pure four-wheel drive mode, the target driving mode is a direct four-wheel drive mode, the preset condition of starting the engine is met at the same time, and the target gear is 1 gear, so that the determined target clutch is the first clutch. For ease of explanation, the first clutch will be referred to as the K1 clutch and the second clutch will be referred to as the K2 clutch.

The engine start control method in the present embodiment is described below with reference to the first, second, and third timing charts of the engine start flow in fig. 8a to 8 c:

if the HCU determines that the engine needs to be started, i.e., the HCU determines that the preset condition for starting the engine is satisfied, the HCU may perform S201 to S208 as follows:

S201, an engine start preparation request is sent to the EMS/TCU.

S202, a K2 clutch opening request is sent to the TCU.

S203, a K1 clutch torque control request is sent to the TCU.

S204, sending an odd-axis target gear request to the TCU. The odd-axis target gear request carries an odd-axis target gear, and the odd-axis target gear is 1 gear.

S205, sending an even-axis target gear request to the TCU. The even shaft target gear request carries an even shaft target gear, and the even shaft target gear can be 2 gears.

S206, sending a target gear request to the TCU. The target gear request carries a target gear, which may be 1 st gear.

S207, sending a target driving mode request to the TCU. The target driving mode request carries a target driving mode, which is a Direct-Drive four-Drive mode (may be denoted as direct_drive).

S208, sending an engine start-stop type request (comfortable start drive) to the EMS.

It should be noted that fig. 8a to 8c are combined together to form an overall timing chart of the engine start process, so the following description of the variation curve refers to fig. 8a to 8c.

In this embodiment, the order of sending the requests in S201 to S208 is not specifically limited, and may be sequentially sent, or may be simultaneously sent. The following describes the response of each request after the EMS/TCU receives each request:

In S201 above, when the EMS receives the engine start preparation request transmitted from the HCU, the EMS may control the fuel pump to operate to establish the oil pressure. When the TCU receives the engine start ready request sent by the HCU, the TCU may know that the current state of the engine is ready for start. The change curve based on the engine start preparation request shows that: upon entering the engine start phase, the engine start ready request is in an activated state. The starting point in time of the engine start phase may be: a point in time when an engine start preparation request is sent.

In S202 above, after the TCU receives the K2 clutch opening request of the HCU, the TCU may control the K2 clutch to be opened. The change curve based on the actual control request from the HCU's K1/K2 clutch can be seen: at the engine start phase, the actual control Request from the K2 clutch of the HCU is the disconnect Request Open Request. And, based on the change curve of the actual state of the K1/K2 clutch, it can be seen that: when the engine start stage is entered, the actual state of the K2 clutch is the off state, and the actual state of the K2 clutch is the off state all the time throughout the engine start stage.

In S203 above, after the TCU receives the K1 clutch torque control request of the HCU, the TCU may control the K1 clutch to be filled with oil. The change curve based on the actual control request from the HCU's K1/K2 clutch can be seen: the actual control request from the K1 clutch of the HCU is the torque control request Torque Control Request for a period of time during which the engine start phase is entered. And, based on the change curve of the actual state of the K1/K2 clutch, it can be seen that: after entering the engine start phase, the actual state of the K1 clutch is initially in a disengaged state, and when the K1 clutch is completely filled with oil, a torque control mode (which may also be referred to as a torque control state) is entered from the disengaged state. The K1 clutch oil is filled completely, namely the K1 clutch oil pressure reaches the half-engagement Point of the Kiss Point clutch. After the K1 clutch is completely filled with oil, the HCU changes the maximum torque limiting value of the K1 clutch from 0 to the maximum torque value of the K1 clutch.

In S204 above, when the TCU receives the odd-axis target gear request, the TCU may control the synchronizer 1, i.e., the first shifter, to pre-shift based on the odd-axis target gear carried in the odd-axis target gear request. The change curve based on the odd-axis target gear request can be seen: the odd-axis target gear carried in the target gear request from the start of the engine starting stage is 1 gear, namely gear 1 in the figure. As can be seen from the change curve of the synchronizer state: in the process of the synchronizer 1 engaging, the state of the synchronizer 1 changes to: DISENGAGED gear shifting is completed, DISENGAGEMENT gear shifting is completed, synchronization mechanical Synchronization is performed, ENGAGEMENT gear shifting is performed, and Engaged gear shifting is completed.

In S205 above, when the TCU receives the even-axis target gear request, the TCU may control the synchronizer 2, i.e., the second shifter described above, to engage gears based on the even-axis target gear carried in the even-axis target gear request. Since the even shaft gear is already 2-gear before entering the engine start phase, the synchronizer 2 can be maintained in 2-gear. The change curve based on the even-axis target gear request can be seen: after entering the engine starting stage, the even shaft target gear carried in the even shaft target gear request is always 2 gears. And can be seen by the change in synchronizer state: the state of the synchronizer 2 is Engaged, that is, the even shaft gear is always 2, which further illustrates that the even shaft gear is not disengaged in the starting process of the engine in the embodiment of the application.

In S206, after the TCU receives the Target gear request, it may be known that the current Target gear is target_gear_1, i.e. 1 gear. The change curve based on the target gear request can be seen: after entering the engine start phase, the target gear carried in the target gear request is always 1 gear.

In S207 described above, when the TCU receives the target driving mode request, it may be determined that the current driving mode needs to be switched from the pure four-wheel-drive mode to the direct four-wheel-drive mode. Based on the change curve of the target driving pattern, it can be seen that: before entering the engine starting stage, the target driving mode is a pure four-drive mode, and after entering the engine starting stage, the target driving mode is a direct four-drive mode.

In S208 described above, when the EMS receives an engine start-stop type request (comfort start), the engine may be controlled to start in a start type of comfort start. Based on the change curve of the target driving pattern, it can be seen that: after entering the engine start phase, the engine start-stop type is P2 comfort drive start.

When the K1 clutch enters the torque control mode and the maximum torque limit value of K1 is greater than a preset torque value (e.g., 200 Nm) and the actual odd-axle gear is 1, the HCU may perform S209 to S211 as follows:

S209, determining a calibration torque value of the K1 clutch according to the preset engine speed and the temperature of the cooling liquid of the engine, and requesting the K1 clutch to work with the calibration torque value to enable the K1 clutch to enter a slipping state. For example, the calibration torque value is within 100Nm when the preset engine speed is less than 600rpm and the coolant temperature is 0 ℃, 20Nm when the preset engine speed is less than 900rpm and the coolant temperature is 0 ℃, and 0Nm when the preset engine speed is less than 1000rpm and the coolant temperature is 0 ℃.

S210, sending a torque increasing request of the TM motor to the TMCU.

S211, the engine start-stop mode is set to "start".

In S209, the K1 clutch operates with a calibrated torque value, and specifically, a change curve of the K1 clutch torque in the timing chart corresponding to the torque may be referred to. From the K1 clutch torque profile, it can be seen that: after the K1 clutch enters the torque control mode, the K1 clutch torque is gradually increased until it stabilizes at the calibrated torque value over a period of time.

In S210 described above, the TMCU, after receiving the torque increase request of the TM motor, may control the output torque of the TM motor to follow the torque set point carried in the torque increase request. The TM motor is a front axle motor, so that the change curve of the torque of the front axle motor can be seen by referring to the following equation: the front axle motor torque and the K1 clutch torque are synchronously increased and synchronized to a relatively stable value.

In S211, referring to the variation curve of the engine start-stop mode, it can be seen that the engine start-stop mode is "off" before the engine start-up phase is entered, and the engine start-stop mode is "on" during a period of time immediately after the engine start-up phase is entered.

Upon detecting that the actual rotational speed of the engine reaches a rotational speed threshold (e.g., 900 rpm) corresponding to the coolant temperature of the engine, the HCU may perform S212 to S214 as follows:

s212, sending an engine starting request to the EMS.

S213, an engine torque request is sent to the EMS, wherein the engine torque request carries a preset engine torque (for example, 10 Nm).

S214, the engine start-stop mode is set to "ignition".

In S212 described above, the EMS may perform fuel injection control on the engine after receiving the engine start request. As can be seen from the profile of the engine start request: when it is detected that the actual rotational speed of the engine reaches a rotational speed threshold value corresponding to the coolant temperature of the engine, the engine start request enters an activated state from an inactivated state.

In S213, after receiving the engine torque request, the EMS controls the engine to operate according to the preset engine torque carried in the engine torque request, so as to start the engine. As can be seen from the variation of the engine torque: after the engine start request is entered from the inactive state to the active state, the engine torque begins to be greater than 0 and gradually increases and stabilizes at the preset engine torque for a period of time.

In S214 described above, it can be seen from the change curve of the engine start-stop mode and the change curve of the engine start request: when the engine start request goes from the inactive state to the active state, the engine start-stop mode is changed from "start" to "ignition".

After the engine torque architecture is available (i.e., engine ignition, start-up is successful), the HCU may perform S215 through S218 as follows:

S215, the engine start preparation request and the engine start request are reset to the inactive state.

S216, the engine start-stop mode is set to "torque transmission".

S217, the actual torque value of the K1 clutch is controlled to be reduced to 0Nm.

S218, based on the actual torque value of the K1 clutch, reducing the output torque of the TM motor.

In S215 described above, it can be seen from the change curve of the engine start preparation request, the change curve of the engine start request, and the change curve of the engine torque structure state: the engine torque configuration state changes from "unavailable" to "available" after the engine has stabilized at the preset engine torque for a period of time. When the engine torque structure state becomes "available", both the engine start preparation request and the engine start request enter an activated state from an activated state.

In S216, the change curve of the engine start-stop mode and the change curve of the engine torque structure state can be seen: when the torque structural state of the engine changes from "unavailable" to "available", the engine start-stop mode changes from "ignition" to "torque transmission".

In the above-described S217 and S218, it can be seen from the change curve of the engine torque structural state, the change curve of the K1 clutch torque, and the change curve of the front axle motor torque: when the torque configuration state of the engine changes from "unavailable" to "available", the K1 clutch torque and the front axle motor torque begin to decrease synchronously until they decrease to 0.

After detecting that the actual torque value of the K1 clutch is reduced to 0Nm, the HCU may perform S219 as follows:

s219, a K1 clutch disconnection request is sent to the TCU.

After receiving the K1 clutch off request, the TCU may control the K1 clutch to be off. It can be seen from the profile of the K1 clutch torque and the actual control request from the K1/K2 clutch of the HCU that when the K1 clutch torque decreases to 0, the actual control request from the K1 clutch of the HCU changes from a torque control request to a disconnect request.

After detecting that the K1 clutch is open, the HCU may perform S220 to S221 as follows:

S220, defining an engine target rotating speed curve according to the current vehicle speed and the target gear, namely the gear ratio of 1 gear.

S221, activating a speed controller in the HCU, and constructing an engine torque command and transmitting the engine torque command to the EMS.

After the EMS receives the engine torque command constructed by the HCU, the engine torque is controlled to follow a torque set value in the engine torque command so as to track an engine target rotating speed curve, and the actual rotating speed of the engine is matched with the current vehicle speed. The engine speed change curve and the engine torque change curve can be seen: in the process of increasing the engine torque, the engine speed is gradually increased until the target 1 st gear speed is reached, namely, the input shaft speed under the 1 st gear is reached, and at the moment, the matching of the engine speed and the current vehicle speed is realized.

After detecting that the actual speed difference across the K1 clutch is less than a preset speed difference threshold (e.g., 100 rpm), the HCU may perform S222 to S225 as follows:

s222, sending a K1 clutch no-request to the TCU.

S223, sending a K2 clutch no-request to the TCU.

S224, controlling the engine torque to reach a calibration threshold related to the engine speed (for example, the calibration threshold is 3Nm when the engine speed is less than 900 rpm).

In S222 and S223, a K1 clutch no request and a K2 clutch no request are sent to the TCU, which indicates that the HCU exits the control of the K1 clutch and the K2 clutch at this time, and the TCU controls the states of the K1 clutch and the K2 clutch by its own target gear. The change curve of the actual control request of the K1/K2 clutch from the HCU can be seen: after the engine speed is gradually increased until the target 1 st gear speed is reached and stabilized for a period of time, the actual control request of the K1/K2 clutch becomes unsolicited.

The TCU may control the K1 clutch to be closed for a preset period of time (e.g., 150 ms) after not receiving a control request for the K1/K2 clutch sent from the HCU, and feedback to the HCU that the K1 clutch is in a closed state after the actual torque value of the K1 clutch reaches a calibration threshold related to the engine coolant temperature (e.g., 100Nm when the engine coolant temperature is 0 ℃).

In S224 described above, it can be seen from the engine torque variation curve and the engine speed variation curve that the engine torque is gradually stabilized after the engine speed is stabilized at the target 1 st speed.

After detecting that the K1 clutch is closed, the HCU may perform S226 to S228 as follows:

s225, determining a first torque distributed to an engine and a second torque distributed to a TM motor based on the whole vehicle required torque, controlling the engine to output the first torque, and controlling the TM motor to output the second torque so as to jointly drive the vehicle.

S226, the engine start-stop mode is set to be "normal operation".

S227, setting the actual driving mode to a direct-drive four-drive mode.

It should be noted that, in fig. 8a to 8c, the timing chart for starting the engine by the K1 clutch is shown, and in particular, the engine may also be started by the K2 clutch by the sliding.

In the embodiment of the application, under the pure four-drive mode, if the engine is to be started to enter the direct-drive four-drive mode, the target clutch is determined according to the target gear of the vehicle, and the target clutch is controlled to enter the skid-ground state to start the engine without executing the steps of gear picking, dragging and series cut direct-drive, so that the starting speed of the engine is improved, the vehicle can be prevented from changing into the two-drive mode from the four-drive mode because gear picking is not carried out but skid-ground starting is also avoided, the vehicle can still maintain four-drive running in the starting process of the engine when the vehicle needs to be switched from the pure four-drive mode to the direct-drive four-drive mode, and the ride-through performance and the power performance of the vehicle are ensured not to be influenced.

Fig. 9 is a schematic structural diagram of an engine start control device according to an embodiment of the present application. The control device is arranged in a hybrid vehicle including a hybrid transmission including: the first input shaft and the second input shaft, first input shaft and second input shaft, first input shaft are connected with first clutch, and second input shaft is connected with the second clutch.

As exemplarily shown in fig. 9, the control apparatus includes: an acquisition module 301, configured to acquire a target gear of a vehicle; the determining module 302 is configured to determine, if it is detected that a preset condition for starting the engine is met, a target clutch according to the target gear if the current actual driving mode of the vehicle is a pure four-wheel drive mode and the target driving mode is a direct four-wheel drive mode; wherein, when the target gear is 1 gear or 3 gears, the target clutch is the first clutch, when the target gear is 2 gear or 4 gear, the target clutch is the second clutch, in the pure four-wheel drive mode, the front drive motor and the rear drive motor of the vehicle are in a driving state, the engine is in a flameout state, in the direct four-wheel drive mode, the rear drive motor and the engine are in a driving state, the rear drive motor is used for driving rear wheels, and the engine is used for driving front wheels; a control module 303 for controlling the target clutch to enter a slip state to start the engine.

In a possible implementation manner, the control device further includes: and the oil pre-filling module is used for pre-filling oil to the target clutch before the target clutch is controlled to enter a slipping state to start the engine, so that two clutch plates of the target clutch are attached and the two clutch plates do not transmit torque.

In a possible implementation manner, the control module is configured to control the target clutch to enter a torque control mode, and determine a calibrated torque value of the target clutch according to a preset engine speed and a preset coolant temperature of the engine; controlling the target clutch to work according to the calibrated torque value, so that the target clutch enters a slip state; when the actual rotation speed of the engine is detected to reach a rotation speed threshold value corresponding to the temperature of the cooling liquid of the engine, fuel injection control is carried out on the engine, and the engine is controlled to work according to the preset engine torque so as to start the engine.

In a possible implementation manner, the control device further includes a torque compensation module, configured to control the precursor motor to increase the output torque to compensate for the wheel torque of the vehicle.

In a possible implementation manner, the control device further includes: the sending module is used for sending an engine start preparation request to the EMS before fuel injection control is carried out on the engine so that the EMS controls the fuel pump to work to establish the oil pressure; the control module performs fuel injection control on the engine, and includes: an engine start request is sent to the EMS to cause the EMS to perform fuel injection control on the engine.

In one possible implementation manner, the control module controls the target clutch to enter a torque control mode, and determines a calibrated torque value of the target clutch according to a preset engine speed and a preset coolant temperature of the engine, including: controlling the target clutch to enter a torque control mode, and increasing the maximum torque limit value of the target clutch from 0 to the maximum torque value of the target clutch according to a preset speed; when the maximum torque limit value of the target clutch is increased to be larger than a preset torque value, determining a calibrated torque value of the target clutch according to a preset engine speed and the temperature of cooling liquid of the engine; wherein the preset torque value is smaller than the maximum torque value.

In a possible implementation manner, the control device further includes: the exit module is used for determining a target rotating speed matched with the current speed of the vehicle after the engine is started and controlling the engine to run according to the target rotating speed; after the actual rotation speed of the engine is successfully matched with the current vehicle speed, the control of the target clutch is exited so that the TCU controls the target clutch according to the target gear.

In a possible implementation manner, the control device further includes: and the clutch control module is used for determining a target rotating speed matched with the current speed of the vehicle after the engine is started and controlling the target clutch to be disconnected before the engine is controlled to run according to the target rotating speed.

In one possible implementation, the clutch control module is specifically configured to control the actual torque value of the target clutch to decrease to 0, and control the target clutch to be disconnected when the actual torque value of the target clutch decreases to 0.

In a possible implementation manner, the control device further includes: and a motor torque control module for controlling a motor precursor of the vehicle to reduce the output torque when the actual torque value of the target clutch is controlled to be reduced to 0.

Illustratively, as shown in FIG. 10, the vehicle includes: a memory 401 and a processor 402, wherein the memory 401 stores executable program code, and the processor 402 is used for calling and executing the executable program code to execute a control method for starting the engine.

In addition, the embodiment of the application also protects a device, which can comprise a memory and a processor, wherein executable program codes are stored in the memory, and the processor is used for calling and executing the executable program codes to execute the engine starting control method provided by the embodiment of the application.

In this embodiment, the functional modules of the apparatus may be divided according to the above method example, for example, each functional module may be corresponding to one processing module, or two or more functions may be integrated into one processing module, where the integrated modules may be implemented in a hardware form. It should be noted that, in this embodiment, the division of the modules is schematic, only one logic function is divided, and another division manner may be implemented in actual implementation.

In the case of dividing the respective function modules by the respective functions, the apparatus may further include an acquisition module, a determination module, a control module, and the like. It should be noted that, all relevant contents of each step related to the above method embodiment may be cited to the functional description of the corresponding functional module, which is not described herein.

It should be understood that the apparatus provided in this embodiment is used to perform the above-described control method for engine start, and thus the same effects as those of the above-described implementation method can be achieved.

In case of an integrated unit, the apparatus may comprise a processing module, a memory module. Wherein, when the device is applied to a vehicle, the processing module can be used for controlling and managing the action of the vehicle. The memory module may be used to support the vehicle in executing mutual program code, etc.

Wherein a processing module may be a processor or controller that may implement or execute the various illustrative logical blocks, modules, and circuits described in connection with the present disclosure. A processor may also be a combination of computing functions, including for example one or more microprocessors, digital Signal Processing (DSP) and microprocessor combinations, etc., and a memory module may be a memory.

In addition, the device provided by the embodiment of the application can be a chip, a component or a module, wherein the chip can comprise a processor and a memory which are connected; the memory is used for storing instructions, and when the processor calls and executes the instructions, the chip can be caused to execute the engine starting control method provided by the embodiment.

The present embodiment also provides a computer-readable storage medium having stored therein computer program code which, when run on a computer, causes the computer to execute the above-described related method steps to implement a method for controlling engine start provided in the above-described embodiments.

The present embodiment also provides a computer program product which, when run on a computer, causes the computer to perform the above-described related steps to implement a method for controlling engine start provided by the above-described embodiments.

The apparatus, the computer readable storage medium, the computer program product, or the chip provided in this embodiment are used to execute the corresponding method provided above, and therefore, the advantages achieved by the apparatus, the computer readable storage medium, the computer program product, or the chip can refer to the advantages of the corresponding method provided above, which are not described herein.

It will be appreciated by those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional modules is illustrated, and in practical application, the above-described functional allocation may be performed by different functional modules according to needs, i.e. the internal structure of the apparatus is divided into different functional modules to perform all or part of the functions described above.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of modules or units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another apparatus, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims

1. A control method of engine start, characterized by being applied to a hybrid vehicle including a hybrid transmission, the hybrid transmission comprising: a first input shaft connected with a first clutch and a second input shaft connected with a second clutch, the control method comprising:

Acquiring a target gear of a vehicle;

Under the condition that the current actual driving mode of the vehicle is a pure four-wheel drive mode and the target driving mode is a direct four-wheel drive mode, if the condition that the preset condition of starting an engine is met is detected, determining a target clutch according to the target gear; when the target gear is 1 gear or 3 gears, the target clutch is the first clutch, when the target gear is 2 gear or 4 gear, the target clutch is the second clutch, in the pure four-wheel drive mode, a front drive motor and a rear drive motor of the vehicle are in a driving state, the engine is in a flameout state, in the direct four-wheel drive mode, the rear drive motor and the engine are in a driving state, the rear drive motor is used for driving rear wheels, and the engine is used for driving front wheels;

And controlling the target clutch to enter a slipping state to start the engine.

2. The method of claim 1, wherein the controlling the target clutch to enter a slip state to start the engine comprises:

Controlling the target clutch to enter a torque control mode, and determining a calibration torque value of the target clutch according to a preset engine speed and a preset engine coolant temperature;

Controlling the target clutch to work according to the calibrated torque value, so that the target clutch enters a slipping state;

and when the actual rotating speed of the engine is detected to reach a rotating speed threshold value corresponding to the temperature of the cooling liquid of the engine, performing fuel injection control on the engine, and controlling the engine to work according to the preset engine torque so as to start the engine.

3. The method of claim 2, wherein after said controlling said target clutch to enter torque control mode, said method further comprises:

the precursor motor is controlled to increase the output torque to compensate for the wheel torque of the vehicle.

4. The method of claim 2, wherein prior to fuel injection control of the engine, the method further comprises:

Sending an engine start preparation request to the EMS to enable the EMS to control the fuel pump to work so as to establish the oil pressure;

The fuel injection control of the engine includes:

an engine start request is sent to the EMS to cause the EMS to perform fuel injection control on the engine.

5. The method of claim 2, wherein the controlling the target clutch to enter a torque control mode, determining a calibrated torque value for the target clutch based on a preset engine speed and a coolant temperature of the engine, comprises:

Controlling the target clutch to enter a torque control mode, and increasing the maximum torque limit value of the target clutch from 0 to the maximum torque value of the target clutch according to a preset speed;

When the maximum torque limit value of the target clutch is increased to be larger than a preset torque value, determining a calibrated torque value of the target clutch according to a preset engine speed and the temperature of cooling liquid of the engine; the preset torque value is smaller than the maximum torque value.

6. The method of claim 1, wherein after the engine is started, the method further comprises:

determining a target rotating speed matched with the current speed of the vehicle, and controlling the engine to operate according to the target rotating speed;

After the actual rotation speed of the engine is successfully matched with the current vehicle speed, the control of the target clutch is exited, so that the TCU controls the target clutch according to the target gear.

7. The method of claim 6, wherein after the engine is started, the determining a target rotational speed that matches a current vehicle speed of the vehicle, and controlling the engine to operate at the target rotational speed, the method further comprising:

And controlling the target clutch to be disconnected.

8. The method of claim 7, wherein the controlling the target clutch to open comprises:

and controlling the actual torque value of the target clutch to be reduced to 0, and controlling the target clutch to be disconnected in the case that the actual torque value of the target clutch is reduced to 0.

9. The method of claim 8, wherein when the actual torque value controlling the target clutch decreases to 0, the method further comprises:

Controlling a front-drive motor of the vehicle to reduce the output torque.

10. An engine start control device, characterized by being disposed in a hybrid vehicle including a hybrid transmission, the hybrid transmission comprising: a first input shaft and a second input shaft, the first input shaft being connected with a first clutch, the second input shaft being connected with a second clutch, the control device comprising:

the acquisition module is used for acquiring a target gear of the vehicle;

The determining module is used for determining a target clutch according to the target gear if the preset condition for starting the engine is detected to be met under the condition that the current actual driving mode of the vehicle is a pure four-wheel drive mode and the target driving mode is a direct four-wheel drive mode; when the target gear is 1 gear or 3 gears, the target clutch is the first clutch, when the target gear is 2 gear or 4 gear, the target clutch is the second clutch, in the pure four-wheel drive mode, a front drive motor and a rear drive motor of the vehicle are in a driving state, the engine is in a flameout state, in the direct four-wheel drive mode, the rear drive motor and the engine are in a driving state, the rear drive motor is used for driving rear wheels, and the engine is used for driving front wheels;

And the control module is used for controlling the target clutch to enter a slipping state so as to start the engine.

11. A vehicle, characterized in that the vehicle comprises:

A memory for storing executable program code;

A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method of any one of claims 1 to 9.

12. A computer readable storage medium, characterized in that the computer readable storage medium stores a computer program which, when executed, implements the method according to any one of claims 1 to 9.