JP3931465B2 - Engine start control device, control method, and hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a starting control system that appropriately executes a judgment of perfect ignition in the engine at starting. SOLUTION: An engine, motor MG1, motor MG2, and axle are connected via planetary gears to constitute a hybrid vehicle. The engine is cranked to start by means of the torque of the motor MG1. If the engine speed is lower than the igniting speed Netag, the torque of the motor MG1 is changed according to a predetermined pattern. After the igniting speed is achieved and the engine operation is started, the torque of MG1 is set by PI control so that the engine speed becomes a predetermined target speed N1*. The target speed N1* is set lower than an engine idling speed Ne*. When the engine starts self-sustaining operation at the idling speed Ne*, the torque of the motor MG1 changes into the negative region. With this change of torque, reliable judgement of perfect ignition can be executed.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a start control device and a control method for starting an engine by the power of an electric motor coupled to the engine. The present invention also relates to a hybrid vehicle using an engine and an electric motor as power sources and mounting the engine start control device.
[0002]
[Prior art]
In recent years, hybrid vehicles including an engine and an electric motor as power sources have been proposed. Hybrid vehicles include series hybrid vehicles and parallel hybrid vehicles. The series hybrid vehicle is a hybrid vehicle in which the engine is only coupled to the generator and is not mechanically coupled to the drive shaft. In series hybrid vehicles, a generator can be driven by engine power to generate electricity. In addition to being used for charging the battery, this electric power is supplied to a driving motor coupled to the drive shaft. The series hybrid vehicle travels with the power of the electric motor. Mechanical power from the engine cannot be transmitted directly to the drive shaft.
[0003]
A parallel hybrid vehicle refers to a hybrid vehicle in which an engine and a drive shaft are mechanically coupled. In addition to the drive shaft, the engine is coupled to a generator. In the parallel hybrid vehicle, at least a part of the power output from the engine can be transmitted to the drive shaft. It is also possible to generate power by driving a generator coupled to the engine with the power of the engine. Furthermore, it can also drive | run by powering the electric motor couple | bonded with the drive shaft. By powering the electric motor, the power transmitted from the engine to the drive shaft can be supplemented, and the required power can be output from the drive shaft to travel.
[0004]
In the hybrid vehicle described above, the operation of the engine is controlled in accordance with the traveling state of the vehicle. For example, in a series hybrid vehicle, the operation of the engine is stopped when the battery is charged with sufficient power for powering the motor. When the battery power is consumed and charging is required, the engine is started and charging is started. In a parallel hybrid vehicle, the engine is stopped at the start and the vehicle travels using the power of the electric motor. When the vehicle reaches a predetermined vehicle speed, the engine is started and travels using the power of the engine. The start / stop of the engine is controlled according to the state of charge of the battery, similar to the series hybrid vehicle.
[0005]
In a vehicle that uses only an engine as a power source, the engine is usually in an operating state while the vehicle is running. In a normal vehicle, a driver operates an ignition switch to start an engine when driving the vehicle. When the driver turns on the ignition switch, the engine is cranked by the power of the so-called cell motor. When the engine speed reaches about several hundred rpm, fuel is injected and ignited to start the engine operation. When the operation is started, the engine speed rapidly increases to about 1000 rpm. The driver recognizes that the self-starting of the engine is started from the fluctuation of the rotational speed, and completes the operation for starting the engine.
[0006]
On the other hand, in a hybrid vehicle, the engine is started and stopped during traveling regardless of the driver's operation. In the hybrid vehicle, the start control device starts the engine in response to the engine start request. When the start control device receives the engine start request, the start control device powers the electric motor coupled to the engine and executes cranking. When the engine reaches a predetermined rotational speed, fuel is injected and ignited to start the operation of the engine. When it is determined that the engine has started a self-sustained operation (hereinafter referred to as a complete explosion determination), the start control device ends the process for starting the engine.
[0007]
[Problems to be solved by the invention]
In a hybrid vehicle, the engine is repeatedly started and stopped during traveling. Therefore, it is preferable to start the engine smoothly in order to ensure a sufficiently comfortable ride. In order to realize such starting, in a hybrid vehicle, the number of revolutions is increased to the vicinity of the number of revolutions during independent operation by cranking, and then fuel injection and ignition are performed. For this reason, the fluctuation of the rotational speed before and after the start of the autonomous operation is relatively small, and it is difficult to determine whether or not the engine has started the autonomous operation from the rotational speed of the engine. In the conventional hybrid vehicle, the complete explosion determination of the engine is made based on the engine speed and the elapsed time after ignition.
[0008]
However, in such a method, there is a case where an appropriate complete explosion determination cannot be performed. For example, when the elapsed time after ignition is set short, there is a possibility that the operation of the electric motor is stopped even though the engine has not sufficiently started the self-sustained operation. As a result, the engine may stop without being able to start the self-sustaining operation due to the friction load of the power system. On the contrary, when the elapsed time is set to be long, the electric motor is operated even though the engine has already started the self-sustained operation, and the power consumption has increased.
[0009]
In the case of a parallel hybrid vehicle, if the above-described elapsed time is set to be long, the responsiveness of the running vehicle is impaired. This is because it is desired to quickly finish the engine start control during traveling and shift to traveling using the power of the engine. Furthermore, the time until the engine starts a self-sustained operation varies depending on various operating conditions such as the engine water temperature. The conventional start control device has not been able to make an appropriate complete explosion determination suitable for all of these situations.
[0010]
The above-described problems are not limited to hybrid vehicles. This was a common problem for all start control devices that required the determination of engine self-sustained operation. The present invention has been made to solve such a problem, and an object of the present invention is to provide a start control device and a control method capable of appropriately performing a complete explosion determination of an engine. It is another object of the present invention to provide a hybrid vehicle to which such a start control device is applied.
[0011]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the above problems, the present invention adopts the following configuration.
The start control device of the present invention comprises:
A start control device for rotating the engine by the power of an electric motor coupled to the engine and supplying the fuel and igniting the engine so that the engine operates independently.
Power setting means for setting the required power during the self-sustaining operation of the engine;
Engine control means for controlling the operation of the engine in an operation state corresponding to the required power;
Electric motor control means for rotating the electric motor at an electric motor target speed that is significantly lower than the engine speed realized by the engine control means within a range not impeding the operation of the engine;
The gist of the invention is that it comprises a self-sustained operation judging means for judging whether or not the engine has started a self-sustained operation based on the torque of the electric motor.
[0012]
According to such a start control device, the complete explosion determination of the engine can be appropriately performed based on the variation appearing in the motor torque as a result of the interaction between the engine control means and the motor control means. That is, according to the starting device, after the engine self-sustained operation is started, the engine control means operates the engine in an operation state corresponding to the required power. There are various modes of control by the engine control means. For example, the product of the rotation speed and torque, that is, the output power can be controlled to correspond to the required power. Further, the engine may be controlled to operate at a predetermined rotational speed determined according to the required power. Naturally, the engine control means cannot function effectively in a state where the engine has been supplied with fuel and ignited, but has not started independent operation, and the engine is in an operating state corresponding to the required power. Don't be.
[0013]
On the other hand, in the start control device of the present invention, the motor control means controls the rotation of the motor. Since this electric motor is coupled to the engine, the rotational speed of the engine is indirectly controlled. That is, the electric motor control means controls the electric motor to rotate the engine at a rotational speed significantly lower than the rotational speed realized by the engine control means. After the engine starts a self-sustained operation and the engine control means starts to function effectively, a negative torque is output from the electric motor in order to reduce the rotational speed to the electric motor target rotational speed. Before the engine starts self-sustaining operation, that is, when the engine control means is not functioning effectively, the engine speed is lower than the motor target speed. Torque is output.
[0014]
Thus, according to the start control device of the present invention, the engine operating state is controlled by the two means of the engine control means and the electric motor control means. As a result, the output torque of the motor fluctuates depending on whether the engine control means functions effectively, that is, whether the engine has started a self-sustaining operation. In the start control device of the present invention, it is determined whether or not the engine has started a self-sustained operation based on the variation in the torque of the electric motor thus generated. The fluctuation of the torque of the electric motor can be easily and accurately detected based on the torque command value by the electric motor control means. Therefore, according to the start control device of the present invention, the complete explosion determination can be performed appropriately.
[0015]
Here, the terms in this specification are defined. In this specification, “start” refers to a state from when the engine is stopped until it starts independent operation. Self-sustained operation means that the engine is in an operating state in which the engine can continue to rotate without torque from the electric motor. In the beginning of fuel injection and ignition in the engine, it may not be possible to perform autonomous operation yet. In this specification, the term “start of operation” is simply used for such a state.
[0016]
As described above, the motor target speed is the target speed of the engine used for setting the torque of the motor. Accordingly, whether or not the motor target rotational speed is significantly lower than the engine target rotational speed is determined in a state immediately before the power output from the motor is transmitted to the engine. For example, when the electric motor is coupled to the engine via the transmission, the rotation speed immediately before being transmitted to the engine via the transmission is set as the motor target rotation speed. The present invention includes a case where the rotational speed of the motor itself is not significantly lower than the engine rotational speed, such as when the motor is coupled to the engine via the transmission.
[0017]
Note that the significantly low rotational speed range is a range in which fluctuations in the torque of the motor can be detected based on the above-described control. If the motor target speed is made extremely lower than the engine speed, the load applied by the motor after the engine starts a self-sustaining operation increases. This load may hinder engine rotation and stop operation. Further, when the motor target rotational speed is lower than the rotational speed at which the engine is ignited, the rotational speed of the engine cannot be sufficiently increased and the operation cannot be started. The “range that does not hinder engine operation” in the present invention means a range that does not hinder the start and continuation of engine operation.
[0018]
On the other hand, if the motor target rotational speed is set to a value substantially equal to the engine rotational speed, there is a possibility that fluctuations in the power output from the engine and the torque of the motor will not occur. When controlling the operation of the engine based on fluctuations in the rotational speed, it is usual to provide a predetermined dead zone in order to avoid frequent fluctuations in the operating state of the engine. It is desirable to set the target motor speed at least within a range outside this dead zone.
[0019]
In the present invention, the engine speed serving as a reference for setting the motor target speed varies depending on the engine control mode by the engine control means. For example, when the engine is controlled to rotate at a predetermined rotational speed, the rotational speed may be set as the engine rotational speed.
[0020]
On the other hand, let us consider a case where the engine is controlled so that the requested power is output from the engine, instead of controlling the rotational speed and torque to predetermined values. In such a case, the rotation speed realized by the engine control means varies depending on the load applied to the engine. Usually, the engine is controlled to rotate at a desired rotational speed by applying a load with an electric motor. Therefore, the engine speed realized by the engine control means is the speed realized when there is no load by the electric motor. When the rotation speed realized by the engine control means can vary depending on factors other than the electric motor that loads the engine, it is desirable to set the target motor rotation speed in consideration of the range of such fluctuation.
[0021]
As described above, in the present invention, the required power during the independent operation can be set to various values. Various methods can also be applied to engine control. As described above, the present invention can be configured in various aspects.
In particular, the power setting means is means for setting the required power to a value of 0,
Preferably, the engine control means is means for rotating the engine at a predetermined engine speed.
[0022]
In general, the higher the required power during autonomous operation, the higher the engine speed and the higher the output torque. An engine is usually provided with a plurality of combustion sections, and there are many variations in starting operation at the time of starting. That is, some combustion units may not be able to perform independent operation even after reaching a state where independent operation can be started. Such variation causes vibration at the time of starting. If the required power during the self-sustained operation is small, the power output from each combustion section is small, so the influence due to the variation is small. Therefore, as described above, if the required power is 0, the vibration at the time of starting can be sufficiently reduced.
[0023]
Further, the fuel consumption at the time of start varies depending on the required power. When starting up, there are usually many harmful gases, so-called emissions, after the start of independent operation. The amount of emissions varies depending on the required power. Therefore, as described above, when the required power is set to 0, the fuel consumption and emission at the time of starting can be suppressed.
[0024]
On the other hand, the operation state corresponding to the required power of value 0 includes engine stop and operation in a so-called idle state. Needless to say, in order to properly start the engine, it is desirable for the engine control means to execute control for operating the engine at the rotational speed in the idle state.
[0025]
The operation when the present invention is configured in the above-described manner will be described in detail. After the engine is started, the engine control means operates the engine at a rotational speed corresponding to the idle rotational speed. On the other hand, the motor control means applies a load to the engine so that the engine speed decreases to the motor target speed. The engine control means increases the fuel injection amount and the like so as to resist this load and maintain the idling speed. As a result, the electric motor continues to output negative torque, and the power output from the engine increases. Since the engine speed is controlled by two control means having different target speeds, after the engine starts a self-sustaining operation, the torque of the electric motor becomes negative due to the interaction between the two. Therefore, if the start control device is configured in the above-described manner, it is possible to appropriately determine the complete explosion of the engine.
[0026]
When the required power is 0,
Temperature detecting means for detecting the temperature of the engine;
Preferably, the power setting means is means for setting the required power to a positive predetermined value when the temperature is equal to or lower than a predetermined value determined according to the ease of ignition of the engine.
[0027]
In general, an engine ignites vaporized fuel to obtain power. When the engine temperature is very low, the fuel is usually difficult to vaporize and ignite. According to the start control device, when the engine temperature is equal to or lower than a predetermined value, the required power is set to a positive value. If the required power increases, the amount of fuel injection increases, so combustion is promoted and the engine is easily started. Therefore, according to the start control device, the engine can be appropriately started when the temperature is low. In this case, the required power may be a predetermined constant value or a value corresponding to the engine temperature.
[0028]
The start control device of the present invention is applicable to various devices that need to execute engine start. Of course, the present invention can be applied to various power output apparatuses using only the engine as a power source. In such a case, there is an advantage that the engine can be appropriately started regardless of whether the engine is started and stopped repeatedly during operation of the power output apparatus. In addition, there is an advantage of reducing fuel consumption and emission at start-up.
[0029]
As described above, the present invention can be applied to a power output apparatus using only an engine as a power source, but is preferably applied to a hybrid power output apparatus using an engine and an electric motor as power sources. This is because the hybrid type power output apparatus repeatedly starts and stops the engine during operation. Among them, as described below, it is preferable to apply the start control device of the present invention and configure the invention as a hybrid vehicle.
[0030]
The hybrid vehicle of the present invention
A hybrid vehicle that is mounted with an engine and a first electric motor as a power supply source and that travels while controlling start and stop of the engine by a second electric motor coupled to the engine,
An engine ignition control means for controlling the second electric motor to rotate the engine in response to a start request of the engine, and for supplying and igniting fuel to the engine;
Power setting means for setting the required power during the self-sustaining operation of the engine;
Engine control means for operating the engine in an operation state corresponding to the required power;
Motor control means for rotating the second motor at a motor target speed significantly lower than the engine speed realized by the engine control means within a range not impeding the operation of the engine;
The gist is provided with a self-sustained operation judging means for judging whether or not the engine has started self-sustained operation based on the torque of the second electric motor.
[0031]
According to such a hybrid vehicle, the engine can be appropriately started by the same action as described in the start control device. Since the hybrid vehicle can travel only with the power source of the electric motor, the engine is repeatedly started and stopped during traveling. According to the hybrid vehicle of the present invention, the engine that is repeatedly executed in this manner can be appropriately started, so that stable driving can be realized, and fuel efficiency and emission can be reduced. it can.
[0032]
Note that the hybrid vehicle of the present invention may have either a series hybrid vehicle or a parallel hybrid vehicle. If the above-described first motor and second motor are different motors and a configuration in which the engine and the drive shaft are not coupled is applied, a series hybrid vehicle is obtained. If the first motor and the second motor are different motors and the engine and the drive shaft are combined, a parallel hybrid vehicle having two motors is obtained. Furthermore, if the first electric motor and the second electric motor are a common electric motor, a parallel hybrid vehicle including one electric motor is obtained. The present invention may adopt any configuration.
[0033]
In the hybrid vehicle of the present invention, similar to the start control device described above,
The power setting means is means for setting the required power to a value of 0;
The engine control means is preferably means for rotating the engine at a predetermined engine speed.
If the required power is set in this way, vibration, fuel consumption, and emission at the time of engine start can be suppressed as described in the start control device. In particular, suppression of vibration is preferable in terms of greatly improving the riding comfort of the hybrid vehicle.
[0034]
When the required power is 0,
Temperature detecting means for detecting the temperature of the engine;
The power setting means is preferably means for setting the required power to a positive predetermined value when the temperature is equal to or lower than a predetermined value determined according to the ease of ignition of the engine.
If it carries out like this, it will become possible to start an engine appropriately under low temperature.
[0035]
When the required power is 0, in addition,
Comprising stop determination means for determining whether or not the vehicle is stopped;
The power setting means is preferably means for setting the required power to a positive predetermined value when the vehicle is not stopped.
[0036]
According to such a hybrid vehicle, the required power is set to a value of 0 while the vehicle is stopped, and is set to a positive predetermined value while the vehicle is running. When the engine is started during traveling, it is usually required to travel using the power of the engine. If the vehicle continues to run under such a situation, the battery power is consumed. Therefore, it is desirable to output power quickly from the engine when the engine is requested to start during traveling. According to the hybrid vehicle described above, the required power of the engine is started as a positive predetermined value, so that the power can be output quickly. Therefore, the power consumption of the battery can be suppressed and the responsiveness of the vehicle can be improved.
[0037]
The required power for starting the vehicle during traveling may be a constant value set in advance, or may be a value determined in accordance with the traveling state of the vehicle, for example, the vehicle speed or the accelerator depression amount. In the latter case, the required power may be continuously changed, or may be changed stepwise.
[0038]
Moreover, you may apply combining what makes a request | requirement motive power a positive predetermined value at the time of low temperature in various aspects. For example, the required power may be a value of 0 only when the engine is at a predetermined temperature or higher and the vehicle is stopped, and may be a positive predetermined value in other cases. Further, the required power may be set to a value of 0 when the vehicle is stopped or the engine satisfies any one of the predetermined temperature or higher, and may be a positive predetermined value in other cases. It is possible to apply by combining in various other modes.
[0039]
The present invention can also be configured as an engine control method described below.
That is, the control method of the present invention is
A control method of rotating the engine by the power of an electric motor coupled to the engine and supplying the fuel and igniting the engine to operate independently.
(A) a step of setting a required power during the self-sustaining operation of the engine;
(B) a step of operating the engine in an operation state corresponding to the required power;
(C) rotating the electric motor at a motor target rotational speed that is significantly lower than the engine rotational speed realized by the engine control means within a range that does not impede operation of the engine;
(D) A control method including a step of determining whether or not the engine has started a self-sustained operation based on the torque of the electric motor.
[0040]
According to such a control method, the engine can be started stably and appropriately by the same operation as described above as the start control device. Needless to say, various additional elements described above in the start control device can be applied to the control method. Further, the invention as an engine control method can be configured as an invention of a hybrid vehicle control method.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
(1) Configuration of the embodiment:
First, the configuration of a hybrid vehicle as an embodiment of the present invention will be described. FIG. 1 is an explanatory diagram showing the configuration of a power system that outputs the power of the hybrid vehicle. The engine 150 provided in the power system is a normal gasoline engine, and rotates the crankshaft 156. The engine 150 of the present embodiment includes a mechanism (hereinafter referred to as a VVT mechanism) that can adjust the opening / closing timing of the intake valve and the exhaust valve. The configuration of the VVT mechanism is well known and will not be described in detail.
[0042]
The operation of engine 150 and the VVT mechanism are controlled by EFIECU 170. The EFIECU 170 is a one-chip microcomputer having a CPU, a ROM, a RAM, and the like inside. The CPU executes a fuel injection amount and other controls of the engine 150 in accordance with a program recorded in the ROM.
[0043]
The power system is further provided with motors MG1 and MG2. Motors MG1 and MG2 are synchronous motors, and include rotors 132 and 142 having a plurality of permanent magnets on the outer peripheral surface, and stators 133 and 143 around which three-phase coils 131 and 141 forming a rotating magnetic field are wound. . The stators 133 and 143 are fixed to the case 119. Three-phase coils 131 and 141 wound around stators 133 and 143 of motors MG1 and MG2 are connected to battery 194 via drive circuits 191 and 192, respectively. The drive circuits 191 and 192 are transistor inverters each including two transistors as a switching element for each phase. The drive circuits 191 and 192 are connected to the control unit 190. When the transistors of drive circuits 191 and 192 are switched by a control signal from control unit 190, a current flows between battery 194 and motors MG1 and MG2. The motors MG1 and MG2 can operate as electric motors that are rotated by receiving power supplied from the battery 194 (hereinafter, this running state is referred to as power running), and the rotors 132 and 142 are rotated by external force. Can function as a generator that generates electromotive force at both ends of the three-phase coils 131 and 141 to charge the battery 194 (hereinafter, this running state is referred to as regeneration).
[0044]
Engine 150 and motors MG1 and MG2 are mechanically coupled via planetary gear 120, respectively. The planetary gear 120 includes a planetary carrier 124 having a sun gear 121, a ring gear 122, and a planetary pinion gear 123. The sun gear 121 rotates at the center. The planetary pinion gear 123 revolves while rotating around the sun gear 121. The ring gear 122 rotates around the planetary pinion gear 123. The crankshaft 156 of the engine 150 is coupled to the planetary carrier shaft 127 via the damper 130. The damper 130 is for absorbing torsional vibration generated in the crankshaft 156. Rotor 132 of motor MG1 is coupled to sun gear shaft 125. The rotor 142 of the motor MG2 is coupled to the ring gear shaft 126. The rotation of the ring gear 122 is transmitted to the drive shaft 112 and the wheels 116R and 116L via the chain belt 129.
[0045]
The entire operation of the hybrid vehicle of the embodiment is controlled by the control unit 190. The control unit 190 is a one-chip microcomputer having a CPU, a ROM, a RAM, and the like in the same manner as the EFIECU 170. The control unit 190 is connected to the EFIECU 170, and both can communicate various information. For example, the EFIECU 170 detects the engine water temperature with the water temperature sensor 154. Therefore, the control unit 190 can acquire the engine water temperature by communication. On the contrary, the control unit 190 can indirectly control the operation of the engine 150 by transmitting information such as a torque command value and a rotation speed command value necessary for controlling the engine 150 to the EFIECU 170. Further, by controlling the switching of the drive circuits 191 and 192, the operation of the motors MG1 and MG2 can be directly controlled.
[0046]
In order to realize such control, the control unit 190 includes various sensors, for example, an accelerator pedal position sensor 165 for detecting the amount of depression of the accelerator by the driver, and a rotational speed for knowing the rotational speed of the drive shaft 112. A sensor 144 and the like are provided. Since the ring gear shaft 126 and the drive shaft 112 are mechanically coupled, in this embodiment, a rotation speed sensor 144 for knowing the rotation speed of the drive shaft 112 is provided on the ring gear shaft 126 to control the rotation of the motor MG2. It is common with the sensor for.
[0047]
(2) Basic operation:
In order to explain the basic operation of such a hybrid vehicle, the operation of the planetary gear 120 will be described first. Planetary gear 120 has the property that when the rotational speed and torque of two of the above-described three rotating shafts and the torque (hereinafter collectively referred to as the rotating state) are determined, the rotating state of the remaining rotating shaft is determined. have. The relationship of the rotation state of each rotating shaft is shown in the following equation (1).
[0048]
Nr = (1 + ρ) Nc−ρNs;
Nc = (Nr + ρNs) / (1 + ρ);
Ns = (Nc−Nr) / ρ + Nc;
Ts = ρ / (1 + ρ) × Tc;
Tr = 1 / (1 + ρ) × Tc (1)
[0049]
Here, Ns and Ts are the rotational speed and torque of the sun gear shaft 125, Nr and Tr are the rotational speed and torque of the ring gear shaft 126, and Nc and Tc are the rotational speed and torque of the planetary carrier shaft 127. Further, ρ is a gear ratio between the sun gear 121 and the ring gear 122 as represented by the following equation.
ρ = number of teeth of sun gear 121 / number of teeth of ring gear 122
[0050]
The hybrid vehicle of this embodiment can travel in various states based on the action of the planetary gear 120. For example, in a relatively low speed state where the hybrid vehicle has started to travel, the motor MG2 is powered while the engine 150 is stopped to travel by transmitting power to the drive shaft 112. Similarly, the engine 150 may travel while idling.
[0051]
When the hybrid vehicle reaches a predetermined speed, the control unit 190 powers the motor MG1, and cranks and starts the engine 150 with the torque. At this time, the reaction torque of the motor MG1 is also output to the ring gear 122 via the planetary gear 120. The control unit 190 controls the operation of the motor MG2 so as to output the required power from the drive shaft 112 while canceling out the reaction torque. The control for starting the engine will be described in detail later.
[0052]
In a state where the engine 150 is operating, the power is converted into rotational states of various rotational speeds and torques and output from the drive shaft 112 to travel. When the engine 150 is operated and the planetary carrier shaft 127 is rotated, the sun gear shaft 125 and the ring gear shaft 126 are rotated under conditions that satisfy the above equation (1). The power generated by the rotation of the ring gear shaft 126 is directly transmitted to the wheels 116R and 116L. The power generated by the rotation of the sun gear shaft 125 can be regenerated as electric power by the motor MG1. On the other hand, if the motor MG2 is powered, power can be output to the wheels 116R and 116L via the ring gear shaft 126. When the torque transmitted from the engine 150 to the ring gear shaft 126 is insufficient, the torque is assisted by powering the motor MG2. As the electric power for powering the motor MG2, electric power regenerated by the motor MG1 and electric power stored in the battery 149 are used. Control unit 190 controls the operation of motors MG1 and MG2 in accordance with the required power to be output from drive shaft 112.
[0053]
The planetary gear 120 can rotate the planetary carrier 124 and the sun gear 121 while the ring gear 122 is stopped. Therefore, the engine 150 can be operated even when the vehicle is stopped. For example, when the remaining capacity of the battery 194 decreases, the engine 150 is started and the motor MG1 is regeneratively operated to charge the battery 194. Even if the vehicle is stopped, if the motor MG1 is powered, the engine 150 can be cranked and started by the torque. At this time, the control unit 190 controls the motor MG2 to cancel the reaction torque of the motor MG1.
[0054]
(3) Start control process:
Next, the start control process in the present embodiment will be described. The start control process is a process for cranking the engine 150 with the motor MG1 and injecting and igniting fuel to start a self-sustaining operation. The start control process is repeatedly executed by a CPU (hereinafter simply referred to as a CPU) in the control unit 190 at predetermined time intervals together with various control processes. As described above, in the start control process, first, when the vehicle speed and torque of the hybrid vehicle reach a speed at which the vehicle travels from EV travel using only the motor MG2 as a power source to a normal travel state using engine power. To be executed. Secondly, when the engine 150 is stopped, the remaining capacity of the battery 194 is reduced and it is determined that charging is necessary. The start according to the second condition is performed regardless of whether the vehicle is stopped or traveling.
[0055]
When the start control processing routine is started, the CPU controls the VVT mechanism of the engine 150 and first sets the intake valve closing angle to the most retarded angle (step S100). This setting will be described. FIG. 3 is an explanatory diagram showing opening and closing timings of the intake valve and the exhaust valve by the VVT mechanism. In the engine 150, the piston moves up and down in the cylinder, and accordingly, the crankshaft of the engine 150 rotates in the clockwise direction in the drawing.
[0056]
The opening / closing timing of the intake valve is indicated by a white arrow, and the opening / closing timing of the exhaust valve is indicated by a solid arrow. As shown in the figure, the exhaust valve opens when the crankshaft is at a rotational position slightly before the bottom dead center of the piston and closes when the crankshaft slightly exceeds the top dead center. This timing is fixed. On the other hand, for example, at timing A, the intake valve opens before the top dead center and closes when it slightly exceeds the bottom dead center. Both the intake valve and the exhaust valve are open from the time when the intake valve is opened until the time when the top dead center is slightly exceeded. When the opening / closing timing is changed by the VVT mechanism, only the opening / closing timing of the intake valve changes as in timing B, for example. At this time, the intake valve opens later than the timing A and slightly exceeds the top dead center, and closes when the bottom dead center is greatly exceeded. Although the opening / closing timing of the intake valve is changed, the period in which the intake valve is in the open state is the same for the timing A and the timing B.
[0057]
The opening / closing timing of the intake valve that changes in this way is represented using an angle from the bottom dead center until the intake valve closes, that is, an intake valve closing angle. When the intake valve closing angle is adjusted to be larger than the standard value, the intake valve closes slowly. Such control is called retardation control. When the retard angle control is performed, the stroke for compressing the air-fuel mixture sucked into the combustion chamber is shortened, so that the load at the time of cranking for starting the engine 150 is reduced. In this embodiment, in order to reduce this load in step S100, the intake valve closing angle is controlled to the most retarded angle.
[0058]
Next, the CPU controls the operation of the engine (step S200). FIG. 4 is a flowchart of an engine operation control processing routine. In this process, the CPU determines whether or not the engine 150 has started operation (step S202). When the engine 150 has not started operation, that is, when fuel supply and ignition have not been performed, the CPU ends the engine operation control processing routine. When the start control process routine (FIG. 2) is executed for the first time, the operation of the engine is not started, so the CPU does not execute any process.
[0059]
On the other hand, when the engine 150 has started operation, the CPU determines whether or not the vehicle is stopped (step S204). This determination can be made based on the vehicle speed obtained using the detection signal of the rotation speed sensor 144. It can also be determined based on whether the so-called shift lever position is at the P position used when the vehicle is stopped. And as shown below, the driving | running state of the engine 150 is set according to the driving | running | working state of a vehicle, and control of a driving | running is performed.
[0060]
When it is determined that the vehicle is not stopped, the power corresponding to the traveling state is set as the required power of the engine 150. For this purpose, the CPU inputs the accelerator depression amount and the vehicle speed (step S212). The accelerator depression amount is detected by an accelerator opening sensor 165. Based on these various quantities, the running state of the vehicle, that is, the vehicle speed and the required torque can be detected. The CPU calculates the power required for traveling from the product of the vehicle speed and the required torque, and sets it as the required power Pe * of the engine 150 (step S214).
[0061]
Next, a gradual change process is performed for the required power Pe * thus set (step S216). The gradual change process is a process that suppresses fluctuations in the required power Pe *. This is a process for avoiding the possibility that the driving state of the vehicle becomes unstable due to a sudden fluctuation in the required power Pe * of the engine 150. Specifically, the fluctuation of the required power is suppressed by performing a so-called annealing process by multiplying each of the previous required power and the required power newly set in step S214 by a predetermined weighting factor. ing. Here, an upper limit guard process is performed at the same time so that the rate of change from the previous required power to the result value subjected to the annealing process is equal to or less than a predetermined value.
[0062]
In the present embodiment, an upper / lower limit guard process is further performed on the required power Pe * thus set (step S218). That is, the value of the required power Pe * is corrected so as to fall within the range of “0 ≦ Pe * ≦ Pmax”. For example, when the required power Pe * is smaller than the value 0, the value 0 is set to the required power Pe *. When the required power Pe * is larger than the value Pmax, the value Pmax is set to the required power Pe *. The value Pmax is an upper limit value of the required power that is set in a range that does not cause vibrations and other unstable driving conditions that cannot be overlooked in the engine 150 at the time of starting.
[0063]
When the required power of engine 150 is set in this way, next, target engine speed Ne * of engine 150 is set based on the operating curve (step S220). FIG. 5 is an explanatory diagram showing an operation curve. A curve B in the figure shows the rotation speed and torque limit values at which the engine 150 can operate. Curves indicated by α1%, α2%, and the like are isoefficiency lines at which the operating efficiency of the engine 150 becomes constant, and show that the efficiency decreases in the order of α1% and α2%. As shown in the figure, the efficiency of the engine 150 is high at relatively limited operation points, and the efficiency gradually decreases at the surrounding operation points.
[0064]
The curves indicated by C1, C2, and C3 are curves in which the power output from the engine 150 is constant. A1, A2, and A3 indicate points at which the driving efficiency is highest when the power of the curves C1, C2, and C3 is output, respectively. In addition, the curve of C1-C3 is a curve which can be drawn innumerably according to required power, and the torque and rotation speed with high driving efficiency can be selected according to each required power. A curve depicting innumerable operating points with high efficiency selected in this way is a curve A in the figure, which is called an operation curve.
[0065]
In step S220 of the engine operation point setting process, a target rotational speed Ne * with good operation efficiency is selected from the operation curve. FIG. 5 shows the entire region where the engine 150 can be operated. The engine operation point setting process routine of FIG. 4 is a process when the engine 150 is started, and is a process that is executed in a state where the required power is relatively low. Therefore, a relatively low rotational speed and low torque portion on the operating curve shown in FIG. 5 is used.
[0066]
At the same time, the CPU turns off the idle flag (step S220). The idle flag is a flag for instructing execution of control for idling the engine 150. While the vehicle is traveling, the operation of the engine 150 is controlled with priority on the required power Pe *. Therefore, in order to instruct execution of such control, the idle flag is turned off.
[0067]
When the operating point during traveling is set in this way, the CPU controls the operation of engine 150 (step S222). The EFIECU 170 actually controls the operation of the engine 150. Accordingly, here, the CPU indirectly controls the operation of the engine 150 by outputting the required power Pe * to the EFIECU 170. The EFIECU 170 controls the fuel injection amount, throttle opening, ignition timing, intake valve closing angle by the VVT mechanism, and the like according to the required power Pe *.
[0068]
It is not possible to control both the required power Pe * and the rotational speed Ne * only by controlling the operation of the engine 150. The EFIECU 170 only controls the engine 150 so that the required power Pe * is output, and the number of revolutions is determined according to the load applied to the engine 150 as a result. When the engine 150 is started during traveling, the power necessary for traveling has already been output by the motor MG2, and therefore the traveling load is hardly applied to the engine 150. Therefore, if only the control in step S222 is executed, the engine 150 rotates at a very high rotational speed. In the present embodiment, as will be described later, the motor MG1 applies a load to the engine 150 to realize the target rotational speed Ne * set in step S220.
[0069]
When it is determined in step S202 that the vehicle is stopped, the CPU executes control for driving the engine 150 in a so-called idle state. The CPU inputs the water temperature of the engine 150 detected by the water temperature sensor 154 (step S232). The CPU sets the required power of engine 150 based on this water temperature (step S234). The required power during the stop is preset as a map corresponding to the water temperature. FIG. 6 is an explanatory diagram showing a map that gives the required power Pe *. As shown in the figure, when the engine water temperature is lower than a predetermined temperature tmp2, the required power is set to a predetermined positive value ptmp. The required power is set to 0 in the range where the engine water temperature is equal to or higher than the temperature tmp1. Between the temperatures tmp2 and tmp1, the required power gradually changes according to the engine water temperature.
[0070]
In general, when the engine water temperature is low, it is difficult to start the engine 150 because the fuel is difficult to vaporize. In this case, if the required power is set to a positive predetermined value, the intake amount and fuel injection amount of the engine 150 are increased, and the engine 150 can be easily started. In this embodiment, from this point of view, when the water temperature is so low that it is difficult to start the engine 150 (a state equal to or lower than tmp1 in FIG. 6), the required power is ptmp. In this embodiment, the temperature tmp1 is −10 ° C., the temp2 is −20 ° C., and the ptmp is 4 kW. For these parameters, appropriate values may be selected according to the type of engine mounted.
[0071]
Next, the CPU sets a target rotational speed Ne * of the engine 150 (step S236). The target rotational speed Ne * is set in advance as a map of the engine water temperature, as with the required power. FIG. 7 is an example of a map that gives the target rotational speed Ne *. As shown in the figure, when the engine coolant temperature is equal to or lower than a predetermined value tmp3, the target rotational speed Ne * is set to the value Nt1. When the engine water temperature exceeds tmp3, the target rotational speed Ne * gradually decreases, and at the temperature tmp4 or higher, the target rotational speed Ne * becomes the value Nt2. When the engine water temperature is relatively low, a slightly high rotational speed is set as the target rotational speed in order to promote warm-up of the engine 150. In this embodiment, the value Nt1 is set to 1300 rpm and the value Nt2 is set to 1000 rpm. These values may be selected appropriately depending on the type of engine mounted.
[0072]
At the same time, the CPU turns on the idle flag (step S236). When the engine 150 is idling, unlike the control described above in step S222, the EFIECU 170 controls the operation of the engine 150 so as to rotate at the target rotational speed. The CPU turns on the idle flag in order to instruct execution of such control.
[0073]
When the target rotational speed is set in this way, the CPU executes control for idling the engine 150 at the rotational speed (step S238). As described above, the CPU indirectly controls the operation of the engine 150 by transmitting necessary information to the EFIECU 170. Here, since the idle flag is on, the EFIECU 170 controls the fuel injection amount, the throttle opening, the intake valve closing angle by the VVT mechanism, and the like according to the rotational speed of the engine 150. From the CPU, a flag for instructing execution of such control and the target rotational speed Ne * are output to the EFIECU 170. Thus, when control of the operation of the engine 150 is executed in accordance with the traveling state of the vehicle, the CPU ends the engine operation control processing routine and returns to the start control processing routine (FIG. 2).
[0074]
In the start control process routine, next, control of the operation of the motor MG1 is executed (step S300). FIG. 8 is a flowchart of an MG1 torque T1 setting process routine. When this process is started, the CPU determines whether or not the rotational speed of the engine 150 is greater than a predetermined rotational speed Netag (hereinafter referred to as ignition rotational speed) that is a criterion for determining whether or not to perform ignition (hereinafter referred to as ignition rotational speed). Step S302). The EFIECU 170 performs ignition timing control based on the engine speed Ne. Therefore, the rotational speed Ne of the engine 150 can be detected by communication with the EFIECU 170. The predetermined rotation speed Nettag may be set to a rotation speed suitable for ignition according to the type of engine. In this embodiment, in order to avoid large fluctuations in the rotational speed associated with starting, the value of Netag is set to 1000 rpm, which is substantially equivalent to the idle rotational speed.
[0075]
When the rotational speed Ne is equal to or lower than Netag, control (hereinafter referred to as ramp control) for gradually increasing the torque T1 of the motor MG1 at a predetermined change rate is executed. Therefore, the CPU increases the torque T1 of the motor MG1 by a predetermined increment ΔT (step S310). At the same time, an upper limit guard process is executed for the torque T1 so as not to exceed the predetermined maximum value Tmax (step S312).
[0076]
When the rotational speed of engine 150 is relatively low, even if a large torque is output from motor MG1 due to the influence of inertia, the rotational speed of engine 150 does not increase. In this state, setting the required torque of the motor MG1 to a large value leads to wasteful consumption of electric power. In the present embodiment, from this point of view, when the rotation speed Ne is equal to or less than Netag, the motor MG1 is subjected to ramp control.
[0077]
On the other hand, when the rotational speed Ne of the engine 150 is larger than Netag, the CPU feedback-controls the torque of the motor MG1. This feedback control is performed so that the rotational speed Ne of the engine 150 coincides with a predetermined target rotational speed N1 *. However, a different value is applied to the target rotational speed N1 * depending on the traveling state of the vehicle. The CPU determines whether or not the vehicle is stopped (step S320). If the vehicle is not stopped, the value Ne * is substituted for the target rotational speed N1 * (step S322). This value is the value set in step S220 of the engine operation control process (FIG. 4). When the vehicle is stopped, a value obtained by subtracting a predetermined value α from the value Ne * is set as the target rotational speed N1 * (step S324). In this embodiment, as described later, the predetermined value α is set to about 30 to 50 rpm.
[0078]
As described above, when the vehicle is traveling, if the motor MG1 does not apply a load to the engine 150, the engine 150 is operated at a very high rotational speed. The target rotational speeds N1 * and Ne * are lower than the rotational speed realized by the control of the engine 150. On the other hand, when the vehicle is stopped, the engine 150 is controlled to operate at the target rotational speed Ne *. As described in step S322, by setting the value Ne * to a value obtained by subtracting the predetermined value α, the target rotational speed N1 * becomes a value lower than the rotational speed realized by the control of the engine 150. As described above, in this embodiment, the target rotational speed N1 * used for calculating the torque of the motor MG1 is set to a value lower than the rotational speed realized by the control of the engine 150, regardless of the traveling state of the vehicle. .
[0079]
Next, the CPU sets the torque T1 of the motor MG1 by the following equation based on the deviation Δnc between the target rotational speed N1 * thus set and the rotational speed Ne of the engine 150 (step S326).
T1 = k1 · Δnc + k2 · Σ (Δnc)
Δnc = N1 * −Ne
[0080]
The above equation is an equation for setting the torque of the motor MG1 by so-called PI control. The torque T1 is set by the proportional term (first term on the right side) and the integral term (second term on the right side) of the deviation Δnc of the rotational speed. k1 and k2 are constant coefficients previously set by experiments or analysis as gains. When the rotational speed Ne of the engine 150 is higher than the target rotational speed N1 *, the torque T1 of the motor MG1 is a negative value, and when it is low, the torque T1 is a positive value. Since PI control is a well-known technique, further detailed description is omitted. The CPU executes a gradual change process for the torque T1 set in this way (step S328). This is in order to avoid a sudden change in the torque of the motor T1 and an unstable operation state.
[0081]
When the torque T1 of MG1 is set through the above processing, the CPU controls the operation of motor MG1 (step S330). The CPU sets a voltage to be applied to the three-phase coil of the motor MG1 according to the torque T1. The on / off of each transistor constituting the drive circuit 191 is PWM controlled so that this voltage value is applied to the three-phase coil at a phase corresponding to the rotation speed of the motor MG1. The same applies when the torque of the motor MG1 is negative, that is, when the motor MG1 is regeneratively operated. Since PWM control of a synchronous motor is a well-known technique, detailed description is abbreviate | omitted.
[0082]
In parallel with the control of the motor MG1, the CPU measures an elapsed time after the target torque T1 becomes negative (step S332). This is a measurement of the time that is continuously negative. Therefore, if the target torque T1 changes to a positive value after the negative value, the elapsed time is initialized to a value of zero. When the above processing is executed, the CPU ends the motor MG1 control processing routine and returns to the start control processing routine (FIG. 2).
[0083]
Thereafter, the CPU executes a process for controlling the operation of motor MG2 (step S400). The motor MG2 is controlled to output the necessary power to the drive shaft 112 while canceling the reaction force due to the torque of MG1. When torque T 1 is output from motor MG 1, the reaction force is output to ring gear 122 according to equation (1) shown above. While the vehicle is stopped, a torque that cancels the reaction force is set as a target torque of the motor MG2. When the vehicle is traveling, a value obtained by adding a torque necessary for traveling to a torque that cancels the reaction force is set as the target torque of motor MG2. The CPU performs PWM control of on / off of each transistor constituting the drive circuit 192 so that a voltage corresponding to the target torque set in this way is applied to the three-phase coil of the motor MG2.
[0084]
With the above processing, the rotational speed of the engine 150 varies from moment to moment. At the beginning of the start control processing routine, when the engine 150 has a low rotational speed, the rotational speed of the engine 150 gradually increases by ramp-controlling the torque of the motor MG1. The CPU determines whether or not the engine speed Ne thus fluctuating is equal to or higher than the ignition speed Nettag (step S500), and when the engine speed is equal to or higher than the ignition speed Nettag, the fuel injection to the engine 150 is performed. And an ignition process is performed (step S600). As already described, an instruction to execute such processing and start operation of the engine 150 is output to the EFIECU 170. Of course, if the operation of the engine 150 has already started, this processing is not performed. Further, this process is not performed even when the rotational speed Ne of the engine 150 is lower than the ignition rotational speed Nettag.
[0085]
Next, as a complete explosion determination of the engine 150, the CPU determines whether or not the elapsed period after the torque T1 of the motor MG1 becomes negative exceeds a predetermined value Ts (step S700). The complete explosion determination is a determination as to whether or not the engine 150 has started a self-sustaining operation. When engine 150 starts a self-sustained operation, the operation of engine 150 is controlled by the engine operation control process (step S200). As a result, engine 150 is controlled to rotate at a higher rotational speed than target rotational speed N1 *, which is a reference for calculating torque of motor MG1.
[0086]
On the other hand, motor MG1 outputs a negative torque so as to reduce the rotational speed of engine 150 to target rotational speed N1 *. In a state where engine 150 is not operating independently, engine 150 cannot maintain a rotational speed of N1 * or higher with motor MG1 loaded. Therefore, the complete explosion determination can be performed based on whether or not the period during which the torque T1 of the motor MG1 is negative exceeds the predetermined value cs. When the predetermined value cs is exceeded, it is determined that the engine 150 has started a self-sustaining operation, and the CPU ends the start control processing routine. If the value is equal to or less than the predetermined value cs, it is determined that the engine 150 is not operating independently, and the CPU repeatedly executes the processes from steps S200 to S600. The predetermined value cs can be set in advance experimentally or analytically as shown below based on changes in the engine speed at the start, the torque of the motor MG1, and the like.
[0087]
The state of changes in the engine speed, the torque of the motor MG1, and the like accompanying the start control process of the present embodiment will be shown. FIG. 9 is an explanatory diagram showing fluctuations in the engine speed and the like when the start control process is executed while the vehicle is running. As shown in the figure, when the start control of the engine 150 is started at time t1, the torque of the motor MG1 increases up to the maximum torque Tmax at a constant rate of change (see steps S310 and S312 in FIG. 8). The rotational speed of engine 150 gradually increases with the torque of motor MG1.
[0088]
Thus, when the rotational speed of the engine 150 reaches a predetermined ignition rotational speed Netag at time t2, fuel is supplied to the engine 150 and ignition is performed. After reaching the ignition rotation speed Netag, the torque of the motor MG1 is set by PI control (see steps S320 to S328 in FIG. 8). While the vehicle is running, it is set based on the deviation between the target engine speed Ne * of the engine 150 and the actual engine speed Ne. In the section from time t2 to t3, the engine speed is lower than the target speed Ne *, so the torque of the motor MG1 is a positive value.
[0089]
When the rotational speed of the engine 150 reaches the target rotational speed Ne * at time t3, the torque of the motor MG1 turns negative. In this case, if the engine 150 has not started the self-sustained operation, the rotational speed of the engine 150 decreases to a value Ne * or less as shown by the broken line in the figure. Accordingly, the torque of the motor MG1 immediately returns to a positive value.
[0090]
On the other hand, if engine 150 has started a self-sustained operation, engine 150 is controlled to output power Pe *. Therefore, the rotational speed of the engine 150 increases. The motor MG1 outputs a negative torque in order to reduce the rotational speed of the engine 150 to the value Ne *. Thus, the torque of the motor MG1 becomes a negative value for a while until the rotation speed of the engine 150 is stabilized at the value Ne *.
[0091]
When the torque of the motor MG1 turns negative at time t3, the complete explosion determination counter starts measuring elapsed time. If the engine 150 has started self-sustained operation, the complete explosion determination counter increases at a constant rate as shown in the figure. When the elapsed time exceeds a predetermined value cs at time t4, the CPU determines that the engine 150 has started a self-sustained operation and ends the start control.
[0092]
The elapsed time cs serving as a reference for the complete explosion determination is set to an appropriate value that can determine that the engine 150 has started a self-sustaining operation based on such fluctuations in the rotational speed and the like. For example, if the elapsed time cs is set to a small value, the engine 150 starts a self-sustained operation due to the torque fluctuation of the motor MG1 when the engine 150 does not start the self-sustained operation as shown by the broken line in FIG. There is a possibility of misjudging it. On the other hand, if the value cs is set to a large value, the time required for complete explosion determination becomes longer. Further, depending on the response of the control until the rotation speed of the engine 150 is stabilized at Ne *, the torque of the motor MG1 may turn positive for a short time, which may cause an erroneous determination. In the present embodiment, the elapsed time cs is set to several seconds in consideration of these conditions. The elapsed time cs may be changed according to the engine water temperature or the like.
[0093]
Next, the setting of the target rotational speed N1 * used for setting the torque T1 of the motor MG1 while the vehicle is stopped will be described. FIG. 10 is an explanatory diagram showing fluctuations in engine speed and the like when the start control process is executed while the vehicle is stopped. As during traveling, when the start control is started at time t11, the torque T1 of the motor MG1 increases to the maximum value Tmax. When the rotational speed of engine 150 reaches value Netag at time t12, fuel is supplied and ignited, and engine 150 starts operation. Thereafter, the operation of the motor MG1 is PI-controlled (see steps S300 to S328 in FIG. 8).
[0094]
In the period from time t12 to t13, the engine 150 has a lower rotational speed than the PI control target rotational speed N1 *, and therefore the motor MG1 has a positive torque. When the rotational speed of engine 150 exceeds target rotational speed N1 *, torque of motor MG1 turns negative. Here, if engine 150 has not started a self-sustaining operation, the rotational speed of engine 150 immediately decreases, and the torque of motor MG1 again becomes a positive value. This is the same as the change during travel (see FIG. 9).
[0095]
On the other hand, when engine 150 has started a self-sustained operation, engine 150 is controlled to perform an idle operation while the vehicle is stopped (see FIG. 4). The engine 150 is controlled to rotate at the idle speed Ne *. On the other hand, motor MG1 is controlled to operate engine 150 at target rotational speed N1 * lower than idle rotational speed Ne *. Due to the interaction between the two controls, the torque of the motor MG1 continuously becomes a negative value. As a result, the complete explosion determination counter increases at a constant rate after time t13. When the elapsed time exceeds a predetermined value cs at time t14, the CPU determines that the engine 150 has started a self-sustaining operation and ends the start control process.
[0096]
The control for causing the EFI ECU 170 to idle the engine 150 is usually provided with a predetermined dead zone in order to avoid frequent fluctuations in the operating state of the engine 150. That is, the control of the idling operation is normally executed so that the engine speed is within a predetermined range with respect to the idling speed Ne *. If the target engine speed N1 * is equal to the idle engine speed Ne * so that it enters this dead zone, the torque T1 of the motor MG1 becomes almost zero when the engine 150 starts self-sustained operation. It becomes impossible to execute.
[0097]
On the other hand, if the target rotational speed N1 * is set to a value extremely lower than the idle rotational speed Ne *, the operation of the engine 150 may become unstable or stop due to the load of the motor MG1. Further, in the configuration in which the engine 150 and the motor MG1 and the like are coupled via the planetary gear 120 as in the present embodiment, it is also known that rattling noise is generated in the planetary gear 120 when the target rotational speed N1 * is set to a low value. . Furthermore, it is also known that when the target rotational speed N1 * is set to a low value, so-called torsional resonance occurs as a result of unstable rotation of the engine 150. In the present embodiment, in consideration of these conditions, the target rotational speed N1 * is set in a range that does not hinder the operation of the engine 150, and a value lower by about 30 to 50 rpm than the idle rotational speed Ne * is set as the target rotational speed. N1 *. That is, the value α in step S324 in FIG. 8 is set to about 30 to 50 rpm.
[0098]
According to the hybrid vehicle of the present embodiment described above, the complete explosion determination of the engine 150 can be performed with high accuracy, and the engine 150 can be started appropriately. Therefore, it is possible to suppress power consumption when the engine 150 is started. In addition, since engine 150 can be started quickly and reliably, the responsiveness of the traveling vehicle can be improved.
[0099]
Further, in the hybrid vehicle of the present embodiment, the required power of the engine 150 can be started with the value 0 while the vehicle is stopped. As a result, the vibration of the engine 150 at the start can be reduced. Further, it is possible to suppress fuel consumption and emission at the time of starting.
[0100]
In the hybrid vehicle of the present embodiment, when the vehicle is stopped, the target rotational speed N1 * for setting the torque of the motor MG1 is set to a value lower than the idle rotational speed Ne * of the engine 150, thereby reducing the torque of the motor MG1. Based on the complete explosion judgment. As a result, the engine 150 can be started with the required power as a value of 0, and the various effects described above can be obtained. The hybrid vehicle has characteristics that are excellent in fuel consumption and emission, and the above-described effects further improve these characteristics.
[0101]
In the hybrid vehicle of this embodiment, the required power is a positive value when the engine water temperature is low. Therefore, the engine can be properly started when the temperature is low. Further, during traveling, engine 150 is started with required power corresponding to the traveling state. Therefore, the power required for traveling can be quickly output as the engine 150 is started, so that the power consumption of the battery can be suppressed and the responsiveness of the vehicle can be improved.
[0102]
In this embodiment, a hybrid vehicle to which the planetary gear 120 is applied has been exemplified. Regardless of this, the present invention can be applied to a hybrid vehicle having various configurations. FIG. 11 is an explanatory diagram showing a configuration of a hybrid vehicle as a modification. This hybrid vehicle includes a clutch motor CM instead of the planetary gear 120 and the motor MG1. The clutch motor is a counter-rotor electric motor including an inner rotor 202 and an outer rotor 204 that are relatively rotatable. As shown in FIG. 11, the inner rotor 202 is coupled to the crankshaft 156 of the engine 150, and the outer rotor 204 is coupled to the drive shaft 112. Electric power is supplied to the outer rotor 204 via a slip ring 206. A motor MG2 is also coupled to the shaft on the outer rotor 204 side. Other configurations are the same as those of the hybrid vehicle of this embodiment.
[0103]
The power output from the engine 150 can be transmitted to the drive shaft 112 via the clutch motor CM. The clutch motor CM transmits power between the inner rotor 202 and the outer rotor 204 through electromagnetic coupling. At this time, if the rotation speed of the outer rotor 204 is lower than the rotation speed of the inner rotor 202, the electric power corresponding to the slippage of both can be regenerated by the clutch motor CM. Conversely, if electric power is supplied to the clutch motor CM, the rotational speed of the inner rotor 202 can be increased and output to the drive shaft 112. When the torque output from the engine 150 via the clutch motor CM does not coincide with the required torque to be output from the drive shaft 112, the motor MG2 can compensate.
[0104]
If the clutch motor is powered, the engine 150 can be motored and started. During motoring, reaction torque is output to the axle side based on the principle of action and reaction between the inner rotor 202 and the outer rotor 204. This reaction torque can be canceled by the motor MG2. If the present invention is applied to the first hybrid vehicle, it is possible to determine whether or not the engine 150 has completely exploded based on the torque of the clutch motor CM at the time of starting.
[0105]
The present invention can be applied to a so-called series hybrid vehicle as well as a parallel hybrid vehicle that can directly output the power of the engine 150 to the drive shaft. FIG. 12 is an explanatory diagram showing the configuration of the series hybrid vehicle. In the series hybrid vehicle, the crankshaft of the engine 150 is mechanically coupled to the rotating shaft of the generator G. Engine 150 is not coupled to the drive shaft. Electric power can be generated by the generator G by operating the engine 150. The generated power is stored in a battery. On the other hand, a motor M is coupled to the drive shaft. The motor M is rotated by the power of the battery.
[0106]
In the series hybrid vehicle, the engine 150 is operated / stopped according to the charge amount of the battery. When the battery power is consumed and charging is required, the engine 150 is started to start charging. The start is performed by cranking the engine 150 with the generator G. If the present invention is applied to such a series hybrid vehicle, it is possible to determine whether or not the engine 150 has completely exploded based on the torque of the generator G at the time of starting.
[0107]
In addition to the hybrid vehicle, the present invention can also be applied to a normal vehicle using only the engine as a power source. Moreover, it is good also as what is applied to the starting control apparatus which starts the driving | operation of an engine in the various apparatuses which mount an engine as a motive power source irrespective of a vehicle.
[0108]
As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement with a various form. It is. For example, in the above embodiment, various controls are executed by software, but these may be realized by hardware.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a schematic configuration of a hybrid vehicle as an embodiment of the present invention.
FIG. 2 is a flowchart of a start control processing routine.
FIG. 3 is an explanatory diagram showing an intake valve closing angle.
FIG. 4 is a flowchart of an engine operation control processing routine.
FIG. 5 is an explanatory diagram showing an operation curve.
FIG. 6 is an explanatory diagram showing a relationship between engine water temperature and required power.
FIG. 7 is an explanatory diagram showing the relationship between engine water temperature and target rotational speed.
FIG. 8 is a flowchart of an MG1 operation control processing routine.
FIG. 9 is an explanatory diagram showing fluctuations in engine speed and the like when a start control process is executed while the vehicle is running.
FIG. 10 is an explanatory diagram showing fluctuations in engine speed and the like when a start control process is executed while the vehicle is stopped.
FIG. 11 is an explanatory diagram showing a configuration of a hybrid vehicle as a modified example.
FIG. 12 is an explanatory diagram showing a configuration of a series hybrid vehicle.
[Explanation of symbols]
112 ... Drive shaft
116R, 116L ... wheels
119 ... Case
120 ... Planetary Gear
121 ... Sungear
122 ... Ring gear
123 ... Planetary pinion gear
124 ... Planetary Carrier
125 ... Sun gear shaft
126 ... Ring gear shaft
127 ... Planetary carrier shaft
129 ... Chain belt
130 ... Damper
131, 141 ... three-phase coil
132, 142 ... rotor
133, 143 ... Stator
144: Rotational speed sensor
149 ... Battery
150 ... Engine
154 ... Water temperature sensor
156 ... Crankshaft
165 ... Accelerator opening sensor
190 ... Control unit
191 192 Drive circuit
194 ... Battery
202 ... Inner rotor
204 ... Outer rotor
206 ... slip ring

Claims (8)

A start control device for rotating the engine by the power of an electric motor coupled to the engine and supplying the fuel and igniting the engine so that the engine operates independently.
Power setting means for setting the required power during the self-sustaining operation of the engine;
Engine control means for controlling the operation of the engine in an operation state corresponding to the required power;
Electric motor control means for rotating the electric motor at an electric motor target speed that is significantly lower than the engine speed realized by the engine control means within a range not impeding the operation of the engine;
A start control device comprising: a self-sustained operation determination unit that determines whether or not the engine has started a self-sustained operation based on a torque of the electric motor. The start control device according to claim 1,
The power setting means is means for setting the required power to a value of 0;
The engine control means is a start control device which is means for rotating the engine at a predetermined engine speed. The start control device according to claim 2,
Temperature detecting means for detecting the temperature of the engine;
The power control means is a start control device which is means for setting the required power to a positive predetermined value when the temperature is equal to or lower than a predetermined value determined according to the ease of ignition of the engine. A hybrid vehicle that is mounted with an engine and a first electric motor as a power supply source and that travels while controlling start and stop of the engine by a second electric motor coupled to the engine,
An engine ignition control means for controlling the second electric motor to rotate the engine in response to a start request of the engine, and for supplying and igniting fuel to the engine;
Power setting means for setting the required power during the self-sustaining operation of the engine;
Engine control means for operating the engine in an operation state corresponding to the required power;
Motor control means for rotating the second motor at a motor target speed significantly lower than the engine speed realized by the engine control means within a range not impeding the operation of the engine;
A hybrid vehicle comprising: a self-sustained operation determination unit that determines whether or not the engine has started a self-sustained operation based on a torque of the second electric motor. The hybrid vehicle according to claim 4,
The power setting means is means for setting the required power to a value of 0;
The hybrid vehicle, wherein the engine control means is means for rotating the engine at a predetermined engine speed. A hybrid vehicle according to claim 5,
Temperature detecting means for detecting the temperature of the engine;
The hybrid vehicle, wherein the power setting means is a means for setting the required power to a positive predetermined value when the temperature is equal to or lower than a predetermined value determined according to the ease of ignition of the engine. A hybrid vehicle according to claim 5,
Comprising stop determination means for determining whether or not the vehicle is stopped;
The power setting means is a hybrid vehicle which is means for setting the required power to a positive predetermined value when the vehicle is not stopped. A control method of rotating the engine by the power of an electric motor coupled to the engine and supplying the fuel and igniting the engine to operate independently.
(A) a step of setting a required power during the self-sustaining operation of the engine;
(B) controlling the operation of the engine in an operating state corresponding to the required power;
(C) rotating the electric motor at a motor target rotational speed that is significantly lower than the engine rotational speed realized by the engine control means within a range that does not impede operation of the engine;
(D) A control method comprising: determining whether or not the engine has started a self-sustained operation based on the torque of the electric motor.

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