CN115727124A - Heavy full-time full-drive transfer case electric control system - Google Patents

Abstract

The invention provides an electronic control system for a heavy-duty full-time full-drive transfer case. The system controller has two modes of switch control and external command control. The solenoid valve operates to realize the corresponding functions and meet the basic functions of the transfer case; when controlling the power take-off, it can realize the multi-mode switching function of the power take-off under different working conditions; the electronic control system can protect the transfer case gear oil , so that it is at a suitable working temperature. The controller controls the heat exchange between the electric oil pump and the oil cooler through the oil temperature to ensure that the transfer box will not be damaged due to too high or too low oil temperature; the main controller calculates the actual vehicle speed according to the output shaft speed value and the vehicle transmission coefficient, And check with the input shaft speed and gear state to ensure the validity of the vehicle speed. The present invention can feed back the operating state in real time while satisfying basic functions, and has safety redundancy measures and a fault diagnosis mechanism.

Description

An electronic control system of a heavy-duty full-time full-drive transfer

technical field

The invention belongs to the technical field of full-time full-drive transfers, in particular to an electric control system for heavy-duty full-time full-drive transfers.

Background technique

The transfer case is a power transmission device composed of gears, which can distribute the power output by the transmission to each drive axle according to a certain torque ratio, and further realize speed increase or torque increase. It is often used in vehicles driven by multiple shafts. The input shaft of the transfer box is directly connected with the output shaft of the transmission through the universal transmission device, and the output shaft is divided into two directions, front and rear, and connected with each drive axle through the universal transmission device respectively.

For the full-time all-drive transfer box widely used in domestic heavy-duty vehicles, its rated input torque can reach 10000Nm, and its rated speed exceeds 2000r/min. Switching between low gears and low gears can achieve speed increase or torque increase, and no power is transmitted in neutral gear; secondly, it has a differential lock, which can synchronize the speed of the front and rear output shafts to meet the function of all-wheel drive; moreover, it has at least one power take-off interface, It is connected through a universal transmission to meet the power take-off requirements of the bodywork system. The above-mentioned functions are all controlled by air, and the piston is pushed by the cylinder to make the fork or the engaging sleeve move, and then realize the corresponding function. For this pure gear combination structure, in order to prevent the teeth from being damaged by the gears when the gears mesh, it is necessary to ensure that the vehicle is stationary and the transmission is in neutral during operation.

For vehicle operators, in order to control the transfer case more conveniently and safely, it is often used to install the transfer case gear switch, full drive switch and power take-off switch on the vehicle instrument panel, and cooperate with the relay through hard wires , and add certain protective measures to control the corresponding solenoid valve action. The air outlet of the solenoid valve is connected to the corresponding air port of the transfer case body, and the air opening and closing of the air port are controlled to realize various functions. The working state of each function is fed back to the instrument through the on-off signal of the jog switch to prompt the driver. In addition, the vehicle speed sensor installed at the rear of the output shaft of the transfer box outputs a square wave signal, and the vehicle speed can only be displayed normally after it is connected to the instrument for processing.

The transfer case drives the gear oil to lubricate through the rotation of the internal gears to ensure the normal operation of the gears. If the oil level is not suitable, too much or too little will lead to poor lubrication, high temperature of the transfer case oil, and no timely feedback For the driver, the transfer case will be overheated, which will affect the service life of the transfer case, and in more serious cases, the transfer case will be burned.

When the transfer case is running in a low temperature environment, due to the viscosity of the gear oil, when the function is switched, especially when the power take-off is engaged, the teeth of the power take-off often do not mesh reliably. When the transmission is in gear, the gear of the power take-off appears Tooth hitting phenomenon will directly damage the transfer case.

With the traditional control method, the system structure is complicated, the assembly is difficult, and it is not conducive to maintenance. For the operator, there are too many matters to be paid attention to, and the protection mechanism is not misoperated. Due to the negligence of the personnel, the transfer case will be accidentally damaged. The control and feedback signals of each function can only be transmitted through hard wires. The control method and wiring harness system are too complicated, and the degree of electronic control is low, which is not conducive to fault detection. If the oil level is low and the oil temperature is high in the transfer case, if the driver cannot be notified in time, the fault will become more and more serious, until the transfer case is damaged, resulting in the failure of the vehicle to operate normally.

Therefore, it is the most effective way to solve the above problems to design an electronic control system that can realize the conventional functions of the transfer case and monitor the operation status of the transfer case in real time, and has safety redundancy measures and fault diagnosis mechanism.

Contents of the invention

In order to solve the problems existing in the above-mentioned background technology, the present invention provides a heavy-duty full-time full-drive transfer case electronic control system, which not only meets the control requirements of basic functions but also can provide real-time feedback on the operation status of the transfer case, and has safety redundancy measures and fault diagnosis mechanisms.

Specifically, the present invention provides a heavy-duty full-time full-drive transfer case electric control system, including a transfer case assembly, an electric oil pump, an integrated oil cooler, an integrated solenoid valve group, a transfer case gear switch, a full Drive switch, power take-off switch and system controller;

The transfer case assembly, the electric oil pump, the integrated solenoid valve group, the transfer case gear switch, the all-wheel drive switch and the power take-off switch are all electrically connected to the system controller. Connection; the air circuit connection between the integrated solenoid valve group and the transfer case assembly, and the oil circuit connection between the integrated oil cooler and the transfer case assembly;

The transfer case assembly includes an input shaft speed sensor, a high gear signal switch, a low gear signal switch, an all-drive signal switch, an oil temperature sensor, an output shaft speed sensor, an oil level sensor and a power take-off signal switch;

The integrated solenoid valve group includes a high gear solenoid valve, a neutral gear solenoid valve, a low gear solenoid valve, a power take-off solenoid valve and a full drive solenoid valve;

When performing gear switching, full drive control and power take-off control, the system controller judges whether it is within a safe speed range according to the control requirements and the speed collected by the input shaft speed sensor and the output shaft speed sensor ; If so, control the solenoid valve corresponding to the integrated solenoid valve group to work; the system controller simultaneously collects the high gear signal switch, the low gear signal switch, the full drive signal switch, the power take After processing the switch state signal of the instrument signal, it is sent to the digital instrument in the form of a CAN signal;

When performing transfer gear oil protection control, the system controller collects the current value of the oil temperature sensor for conversion processing, outputs the oil temperature, and controls the speed of the electric oil pump according to the oil temperature, so that the gear The oil fully circulates in the integrated oil cooler and exchanges heat with the cooling liquid to form a closed-loop control;

When performing vehicle speed signal collection and processing, the system controller collects the frequency signal of the output shaft speed sensor, and converts the actual vehicle speed according to the transmission coefficient sent by the vehicle; The current gear status of the transfer box, the real-time verification of the vehicle speed, and the effective vehicle speed value are sent to the digital instrument in the form of CAN messages.

As a further description of the present invention, the integrated solenoid valve group also includes an input air source interface, the high gear solenoid valve, the neutral gear solenoid valve, the low gear solenoid valve, the power take-off solenoid valve and The all-drive solenoid valves are all electric-controlled air solenoid valves; the output interfaces of the electric-controlled air solenoid valves are respectively connected to the corresponding functions of the transfer case assembly (high gear, neutral gear, low gear, full drive, take-off, etc.) and the control air port of the power device); and the high gear solenoid valve is a power-off normally ventilated solenoid valve, and the neutral gear solenoid valve, the low gear solenoid valve, the power take-off solenoid valve and the full drive solenoid valve are all It is a gas solenoid valve that normally shuts off when the power is off.

As a further description of the present invention, the high gear signal switch, the low gear signal switch, the full drive signal switch and the power take-off signal switch are all contact type jog switches; The switch has three gears of high, empty and low, and is in the high gear state by default; the full drive switch and the power take-off switch have two gears of off and on, and is in the off state by default.

As a further description of the present invention, the input shaft speed sensor and the output shaft speed sensor are both high-precision electromagnetic sensors, and the system controller collects the frequency value of the high-precision electromagnetic sensor and converts it into a corresponding speed value, Send to the digital instrument in the form of CAN signal.

As a further description of the present invention, the oil temperature sensor and the oil level sensor are current sensors, and the system controller collects the current value of the current sensor and converts it into the corresponding liquid level height and temperature. When the liquid height and oil temperature exceed the set safety threshold, the fault status will be sent to the digital instrument in the form of CAN signal.

As a further description of the present invention, the integrated oil cooler includes a gear oil chamber, a cooling liquid chamber and cooling fins, and realizes heat exchange through circulating heat dissipation; cooling is realized through the cooling fins.

As a further description of the present invention, the electric oil pump adopts a PWM current control method, and the rotation speed of the oil pump is changed according to the magnitude of the control current, thereby controlling the flow rate of the gear oil.

As a further description of the present invention, the system controller reserves an external selection interface for the operation mode of the power take-off, and the external selection interface is connected with the control of the gear switch, the full drive switch and the power take-off switch. The logic is consistent, the system controller collects the status of the gear switch, the full drive switch and the power take-off switch, and sends the control conditions through the CAN bus.

As a further description of the present invention, the system controller is an electronic controller with digital input, frequency value input and current analog input interface; with digital drive interface and PWM drive interface; with two CAN communication interfaces, supporting CAN bus Flashing and calibration functions, CAN messages meet the SAEJ1939 standard.

As a further illustration of the present invention, when performing system fault diagnosis, the system controller monitors in real time and judges whether each sensor and actuator has an open-short fault, whether the input signal value is within a reasonable range, whether the CAN signal has a communication error and the bus node Whether there are faults such as disconnection; when a fault occurs, the fault code is sent to the digital instrument in the form of a CAN message, and the fault diagnosis meets the requirements of the DM1 message in the SAEJ1939 standard.

Compared with the prior art, the present invention has the following beneficial technical effects:

Compared with the original transfer case, after installing the electronic control system, it can provide real-time feedback on the operating status while satisfying the basic functions. It has safety redundancy measures and a fault diagnosis mechanism. The system structure is simple, easy to operate, and convenient for fault maintenance. In the process of operation and use, it can effectively prevent misoperation, improve the use efficiency of the transfer case, and reduce the risk of damage to the transfer case. The main controller can communicate with other electronic control systems of the vehicle through the CAN bus to improve the overall electronic control of the vehicle.

Description of drawings

Fig. 1 is the schematic diagram of the electric control system of the heavy-duty full-time full-drive transfer box provided by the present invention;

Fig. 2 is the structural diagram of the integrated electromagnetic valve group in the electronic control system of the heavy-duty full-time full-drive transfer provided by the present invention;

Fig. 3 is a block diagram of the electronic control system of the heavy-duty full-time full-drive transfer provided by the present invention.

Explanation of reference signs

Transfer case assembly 1, input shaft speed sensor 11, high gear signal switch 12, low gear signal switch 13, full drive signal switch 14, oil temperature sensor 15, output shaft speed sensor 16, oil level sensor 17, power take-off Signal switch 18, electric oil pump 2, integrated oil cooler 3, integrated solenoid valve group 4, high gear solenoid valve 41, neutral gear solenoid valve 42, low gear solenoid valve 43, PTO solenoid valve 44, full drive solenoid valve 45. Transfer gear switch 5, full drive switch 6, power take-off switch 7, system controller 8.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "installation", "installation", "connection" and "connection" should be understood in a broad sense, for example, it may be a fixed connection, It can also be a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

The technical solutions of the present invention will be explained below in conjunction with specific embodiments.

As shown in Figure 1-3, an electronic control system for a heavy-duty full-time full-drive transfer case is provided, including a transfer case assembly 1, an electric oil pump 2, an integrated oil cooler 3, an integrated solenoid valve group 4, a Actuator gear switch 5, full drive switch 6, power take-off switch 7 and system controller 8;

The transfer case assembly 1, the electric oil pump 2, the integrated solenoid valve group 4, the transfer case gear switch 5, the full drive switch 6 and the power take-off switch 7 are all connected with The system controller 8 is electrically connected; the integrated solenoid valve group 4 is connected to the transfer case assembly 1 through an air circuit, and the integrated oil cooler 3 is connected to the transfer case assembly 1 Inter-oil connection;

The transfer case assembly 1 includes an input shaft speed sensor 11, a high gear signal switch 12, a low gear signal switch 13, an all-drive signal switch 14, an oil temperature sensor 15, an output shaft speed sensor 16, an oil level sensor 17 and a Force signal switch 18;

The integrated solenoid valve group 4 includes a high gear solenoid valve 41, a neutral gear solenoid valve 42, a low gear solenoid valve 43, a power take-off solenoid valve 44 and a full drive solenoid valve 45;

The transfer case assembly 1 is a traditional heavy-duty high-power transfer case, which uses gear oil to lubricate the gears, which can realize three gears: high, empty and low. Switching between high and low gears can realize speed increase or torque increase. No power is transmitted in neutral; it has a differential lock, which can synchronize the speed of the front and rear output shafts to meet the function of all-wheel drive; it has at least one power take-off interface, which is connected through a universal transmission to meet the power take-off requirements of the bodywork system. Each function adopts the way of electronically controlled gas, and the piston is pushed by the cylinder to make the fork or the engaging sleeve move, and then realize the corresponding function.

Further, the system controller 8 is an electronic controller, which has digital input, frequency value input and current analog input interfaces; has a digital drive interface and a PWM drive interface; has two CAN communication interfaces, supports CAN bus brushing and Calibration function, CAN message meets SAEJ1939 standard.

Further, the integrated solenoid valve group 4 also includes an input air source interface, the high gear solenoid valve 41, the neutral gear solenoid valve 42, the low gear solenoid valve 43, the power take-off solenoid valve 44 and the full-drive electromagnetic valve 45 are electrically controlled air electromagnetic valves; the output interfaces of the electrically controlled air electromagnetic valves are respectively connected to the corresponding functions of the transfer case assembly 1 (high gear, neutral gear, low gear, full gear, etc.) drive, power take-off) control air port; because the transfer case works in the high gear state for a long time, in order to avoid the high gear solenoid valve being energized and overheated for a long time, the high gear solenoid valve 41 is a normally ventilated solenoid valve when the power is off, so The neutral solenoid valve 42, the low gear solenoid valve 43, the power take-off solenoid valve 44 and the full drive solenoid valve 45 are all power-off and air-off solenoid valves.

Further, the high gear signal switch 12, the low gear signal switch 13, the all-drive signal switch 14 and the power take-off signal switch 18 are all contact type jog switches. The point is closed; the transfer gear switch 5 has three gears: high, empty and low, and is in the high gear state by default; the full drive switch 6 and the power take-off switch 7 have two gears: closing and opening bit, the default is off.

Further, the input shaft speed sensor 11 and the output shaft speed sensor 16 are high-precision electromagnetic sensors, and the system controller 8 collects the frequency value of the high-precision electromagnetic sensor and converts it into a corresponding speed value, so as to The CAN signal is sent to the digital instrument.

Further, the oil temperature sensor 15 and the oil level sensor 17 are current-type sensors, and the system controller 8 collects the current value of the current-type sensor and converts it into the corresponding liquid level height and temperature. When the altitude and oil temperature exceed the set safety threshold, the fault status will be sent to the digital instrument in the form of CAN signal.

Further, the integrated oil cooler 3 includes a gear oil chamber, a cooling liquid chamber and cooling fins, and heat exchange is realized through circulation of heat dissipation; cooling is achieved through the cooling fins.

Further, the electric oil pump 2 adopts a PWM current control mode, and the oil pump speed is changed according to the magnitude of the control current, thereby controlling the gear oil flow rate.

Main functions of transfer case electronic control system:

Basic functions of the transfer case: when performing gear shifting, all-wheel drive control and power take-off control, the system controller 8 according to the control requirements and the rotational speed collected by the input shaft rotational speed sensor 11 and the output shaft rotational speed sensor 16 size, to determine whether it is within the safe speed range; if so, control the operation of the electromagnetic valve corresponding to the integrated electromagnetic valve group 4; the system controller 8 simultaneously collects the high gear signal switch 12, the low gear signal switch 13. After the state signals of the all-wheel drive signal switch 14 and the power take-off signal switch 18 are processed, they are sent to digital instruments in the form of CAN signals.

Multi-state control function of power take-off: Due to the different operating environments of vehicles, various operating conditions often appear, such as parking power take-off, driving power take-off or constant speed control, etc. When the system is designed, the system controller 8 reserves The external selection interface of the power device operation mode, and the external selection interface is consistent with the control logic of the gear switch 5, the full drive switch 6 and the power take-off switch 7, and the system controller 8 collects the The gear switch 5, the full drive switch 6 and the power take-off switch 7 states, and control conditions are sent through the CAN bus to realize different working modes.

Transfer case gear oil protection mechanism: The transfer case gear oil protection mechanism is mainly to prevent the transfer case from being burned or toothed due to too high or too low temperature of the gear oil, which will affect the service life of the transfer case; During oil protection control, the system controller 8 collects the current value of the oil temperature sensor 15 for conversion processing, outputs the oil temperature, and controls the speed of the electric oil pump 2 according to the oil temperature, so that the gear oil The above-mentioned integrated oil cooler 3 fully circulates and exchanges heat with the coolant to form a closed-loop control; when the oil temperature is too high or too low, increase the flow rate of the gear oil to ensure that the gear oil is at a suitable working temperature.

Acquisition and processing function of vehicle speed signal: Acquisition and processing of vehicle speed signal mainly provides effective vehicle speed information to the vehicle instrument through the electronic control system of the transfer case; The frequency signal is converted to the actual vehicle speed according to the transmission coefficient sent by the vehicle; the system controller 8 checks the vehicle speed in real time according to the frequency signal of the input shaft speed sensor 11 and the current gear state of the transfer case, and converts the effective vehicle speed The values are sent to the digital instrument in CAN messages.

Fault diagnosis function: when performing system fault diagnosis, the system controller 8 monitors in real time and judges whether each sensor and actuator has an open-short fault, whether the input signal value is within a reasonable range, whether the CAN signal has a communication error and whether the bus node is disconnected. Line and other faults; when a fault occurs, the fault code is sent to the digital instrument in the form of a CAN message, and the fault diagnosis meets the DM1 message regulations in the SAEJ1939 standard.

The above-mentioned embodiments are preferred examples for realizing the present invention, and the present invention is not limited to the above-mentioned embodiments. Any non-essential additions and substitutions made by those skilled in the art according to the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A heavy full-time full-drive transfer case electric control system is characterized by comprising a transfer case assembly, an electric oil pump, an integrated oil cooler, an integrated electromagnetic valve bank, a transfer case gear switch, a full-drive switch, a power takeoff switch and a system controller;

the transfer case assembly, the electric oil pump, the integrated electromagnetic valve bank, the transfer case gear switch, the full-drive switch and the power takeoff switch are all electrically connected with the system controller; the integrated electromagnetic valve bank is connected with the transfer case assembly through a gas circuit, and the integrated oil cooler is connected with the transfer case assembly through an oil circuit;

the transfer case assembly comprises an input shaft rotating speed sensor, a high gear signal switch, a low gear signal switch, a full-drive signal switch, an oil temperature sensor, an output shaft rotating speed sensor, an oil level sensor and a power takeoff signal switch;

the integrated electromagnetic valve group comprises a high-gear electromagnetic valve, a neutral-gear electromagnetic valve, a low-gear electromagnetic valve, a power takeoff electromagnetic valve and a full-drive electromagnetic valve;

when gear switching, full-drive control and power takeoff control are carried out, the system controller judges whether the system is in a safe rotating speed range or not according to control requirements and rotating speeds acquired by the input shaft rotating speed sensor and the output shaft rotating speed sensor; if yes, controlling the electromagnetic valve corresponding to the integrated electromagnetic valve group to work; the system controller simultaneously collects state signals of the high-gear signal switch, the low-gear signal switch, the full-drive signal switch and the power takeoff signal switch, processes the state signals and sends the processed state signals to a digital instrument in a CAN (controller area network) signal mode;

when the transfer case gear oil protection control is carried out, the system controller collects the current value of the oil temperature sensor to carry out conversion processing, then outputs the oil temperature, controls the rotating speed of the electric oil pump according to the oil temperature, and enables the gear oil to be fully circulated in the integrated oil cooler to exchange heat with the cooling liquid to form closed-loop control;

when vehicle speed signal acquisition processing is carried out, the system controller acquires frequency signals of the output shaft rotating speed sensor and converts the actual vehicle speed according to a transmission coefficient sent by a vehicle; and the system controller checks the speed of the vehicle in real time according to the frequency signal of the input shaft rotation speed sensor and the current gear state of the transfer case, and sends an effective speed value to the digital instrument in a CAN message mode.

2. The electric control system of the heavy-duty full-time full-drive transfer case according to claim 1, wherein the integrated solenoid valve set further comprises an input air source interface, and the high-gear solenoid valve, the neutral-gear solenoid valve, the low-gear solenoid valve, the power take-off solenoid valve and the full-drive solenoid valve are all electric control solenoid valves; the output interface of the electric control gas electromagnetic valve is respectively connected with the control gas port of each corresponding function of the transfer case assembly; and the high-gear electromagnetic valve is a power-off normally-on electromagnetic valve, and the neutral electromagnetic valve, the low-gear electromagnetic valve, the power takeoff electromagnetic valve and the full-drive electromagnetic valve are all power-off normally-off electromagnetic valves.

3. The heavy duty full time full drive transfer case electrical control system of claim 1, wherein said high range signal switch, said low range signal switch, said full drive signal switch and said power take off signal switch are contact jog switches; the transfer case gear switch is provided with three gears of high, idle and low, and defaults to a high gear state; the full-drive switch and the power takeoff switch have two gears of closing and opening and are in a closing state by default.

4. The electric control system of the heavy full-time full-drive transfer case according to claim 1, wherein the input shaft rotation speed sensor and the output shaft rotation speed sensor are both high-precision electromagnetic sensors, and the system controller collects frequency values of the high-precision electromagnetic sensors, converts the frequency values into corresponding rotation speeds, and sends the rotation speeds to the digital instrument in a CAN signal mode.

5. The heavy full-time full-drive transfer case electric control system according to claim 1, wherein the oil temperature sensor and the oil level sensor are all current type sensors, the system controller collects current values of the current type sensors and converts the current values into corresponding liquid level heights and temperature magnitudes, and when the liquid level heights and the oil temperature magnitudes exceed set safety threshold values, a fault state is sent to a digital instrument in a CAN signal mode.

6. The electric control system of the heavy full-time full-drive transfer case according to claim 1, wherein the integrated oil cooler comprises a gear oil cavity, a cooling liquid cavity and a cooling fin, and heat exchange is realized through circulation heat dissipation; the cooling is realized through the cooling fins.

7. The electric control system of the heavy full-time full-drive transfer case according to claim 1, wherein the electric oil pump is in a PWM current control mode, and the rotation speed of the electric oil pump is changed according to the control current, so that the flow rate of gear oil is controlled.

8. The electric control system of the heavy full-time full-drive transfer case according to claim 1, wherein the system controller reserves an external selection interface of a power takeoff operation mode, the external selection interface is consistent with control logics of the gear switch, the full-drive switch and the power takeoff switch, and the system controller collects states of the gear switch, the full-drive switch and the power takeoff switch and sends control conditions through a CAN bus.

9. The electric control system of the heavy-duty full-time full-drive transfer case according to claim 1, wherein the system controller 8 is an electronic controller having digital quantity input, frequency value input and current analog input interfaces; the digital driving interface and the PWM driving interface are provided; the CAN bus flash and calibration system has two CAN communication interfaces, supports CAN bus flash and calibration functions, and CAN messages meet SAEJ1939 standards.

10. The electric control system of the heavy full-time full-drive transfer case according to claim 9, wherein when performing system fault diagnosis, the system controller 8 monitors and judges whether or not there are open/short circuit faults between each sensor and the actuator, whether or not the input signal value is in a reasonable range, whether or not the CAN signal is in communication error, whether or not the bus node is disconnected, and other faults in real time; when a fault occurs, the fault code is sent to the digital instrument in a CAN message mode, and fault diagnosis meets the DM1 message regulation in the SAEJ1939 standard.

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