JP3576969B2 - Vehicle control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a vehicle, and more particularly to a control device for a vehicle that purifies exhaust gas remaining up to an outlet of a catalyst when an internal combustion engine stops after the vehicle stops.
[0002]
[Prior art]
A vehicle in which a gasoline internal combustion engine and a motor generator are combined (hybrid) has been put to practical use as one which aims to suppress global warming by halving carbon dioxide emitted and improve fuel efficiency.
[0003]
This combined system includes a system that drives the output shaft of the internal combustion engine by setting the ratio of the internal combustion engine and the motor generator to be approximately equal, and also includes the internal combustion engine as a main and the motor generator. Accordingly, there is a system that drives the motor generator when the internal combustion engine is started to drive the output shaft of the internal combustion engine. These systems stop the supply of fuel to the internal combustion engine when the vehicle comes to a stop, thereby improving fuel efficiency and the like.
[0004]
Here, since the combined system cannot operate auxiliary equipment such as an air conditioner and an alternator which are drivingly connected to the internal combustion engine with the stop of the internal combustion engine, the internal combustion engine is stopped while the vehicle is stopped. It is also envisaged that while the supply of fuel to the engine is stopped, the motor generator is driven to motor the output shaft of the internal combustion engine to an idling speed. However, there is a problem that a large amount of power obtained by regenerative power generation is consumed depending on the length of the stop time of the wheels, and in order to solve this, while performing the motoring while the wheels are stopped, There has been proposed a technology of a vehicle control device that drives an output shaft of the internal combustion engine by supplying less fuel than required during idling without stopping fuel supply to the internal combustion engine (for example, Japanese Unexamined Patent Application Publication No. H10-163873). 9-158961, JP-A-9-39613, etc.). In the case where auxiliary equipment such as an air conditioner has a drive motor without using the internal combustion engine as a power source, or when the internal combustion engine does not require a compressor to be driven as in winter, the fuel consumption is low. In addition, the supply of fuel to the motoring and the internal combustion engine is stopped to improve exhaust gas performance.
[0005]
[Problems to be solved by the invention]
By the way, in the combined system, the start and stop of the internal combustion engine are frequently repeated until the ignition key is switched from on to off as described above.
[0006]
FIG. 5 shows the flow of exhaust gas when the start and stop of the internal combustion engine are frequently repeated. In general, air introduced from outside through the throttle 13 is supplied from the fuel injection valve 17 through the fuel injection valve 17. Is mixed into the cylinder 19, is ignited by the ignition plug 20, burns, and is discharged to the catalyst 23 side.
[0007]
Here, if the start and stop of the internal combustion engine are frequently repeated, exhaust gas is accumulated between the throttle 13 and the catalyst 23. That is, in the combined system, when the internal combustion engine is stopped in a state where the intake valve 18 and the exhaust valve 22 are both opened, as shown by an arrow, the internal system is present up to the catalyst 23. It can be seen that unpurified exhaust gas flows back from the exhaust valve 22 through the cylinder 19 and the intake valve 18 to the throttle 13 and accumulates.
[0008]
In this case, of the combined system, the system in which the ratio between the internal combustion engine and the motor generator is set to be approximately equal and the system that depends on the motor generator are generated by the motor generator. The torque amount is different, and the latter system generates only about １ ／ to ３ of the torque amount as compared with the motor generator of the former system. In the former system, the internal combustion engine is stopped before the wheels stop, whereas in the latter system, the internal combustion engine is stopped after the wheels stop. It is. This is to avoid a shock when the wheel and the internal combustion engine are interrupted.
[0009]
That is, the present inventor cannot use the pumping by the rotation of the wheels because the motor generator system stops the internal combustion engine after the wheels stop, as described above. Since it is not possible to process exhaust gas for purification, it is necessary to provide a drive command for the output shaft of the internal combustion engine to the motor generator to perform pumping when the supply of fuel to the internal combustion engine is stopped. They have obtained new knowledge.
[0010]
However, the conventional technique is intended to reduce the power consumption required for driving the motor generator and the like. As shown in FIG. 5, when the internal combustion engine is restarted, there is a shortage of oxygen near the cylinder 19. In addition, there is still a problem that the unpurified exhaust gas is directly discharged into the atmosphere due to a lack of oxygen near the catalyst 23 and a decrease in the temperature of the catalyst 23, thereby deteriorating the exhaust gas performance. No particular consideration is given to pumping the internal combustion engine using a motor generator after stopping the fuel supply due to a stop request to the engine.
[0011]
The present invention has been made in view of such a problem, and an object of the present invention is to improve the exhaust gas performance at the time of restarting the internal combustion engine in a vehicle control system including a motor generator. An object of the present invention is to provide a control device for a vehicle that can be achieved.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a control device for a vehicle according to the present invention is basically a control device for a vehicle including an internal combustion engine and a motor generator that drives the internal combustion engine. A drive commanding means for the internal combustion engine, wherein the drive commanding means drives the motor generator to drive the internal combustion engine after the vehicle stops and when the supply of fuel to the internal combustion engine is stopped. It is characterized in that a drive command is issued.
[0013]
The control device for a vehicle according to the present invention configured as described above purifies exhaust gas by pumping the internal combustion engine by the motor generator even after the supply of fuel is stopped. Can be prevented from being released into the atmosphere as it is, and the exhaust gas performance can be improved.
[0014]
In a specific aspect of the vehicle control device according to the present invention, the drive command means outputs a drive command so that the internal combustion engine has a predetermined rotation speed and a predetermined drive time, or the drive command The means is provided with means for correcting the number of revolutions of the internal combustion engine, or the drive command means is provided with means for correcting the drive time of the internal combustion engine.
[0015]
Further, in another specific aspect of the vehicle control device of the present invention, the means for correcting the rotation speed of the internal combustion engine or the means for correcting the drive time of the internal combustion engine includes a state of the exhaust purification device for the internal combustion engine. Correcting the rotation speed or the driving time based on the detected amount, or detecting the state of the exhaust gas purification device of the internal combustion engine is to detect the temperature of the exhaust gas purification device, or detecting the exhaust gas of the internal combustion engine. The detection of the state of the purification device is characterized by detecting the temperature of the cooling water of the internal combustion engine.
[0016]
Further, the control device includes: means for determining an operation mode of the internal combustion engine; means for controlling the motor generator or the internal combustion engine when the internal combustion engine is started based on the operation mode; Means for controlling the motor generator when the supply of fuel is stopped, means for controlling the exhaust gas purification device of the internal combustion engine, and means for controlling the internal combustion engine when the vehicle is running and generating electricity, and the drive command means is A driving command for the internal combustion engine is given to the motor generator in accordance with an output signal from a means for controlling the motor generator when the supply of fuel to the internal combustion engine is stopped.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a vehicle control device according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an overall configuration of a control system including a vehicle control device according to the present embodiment.
In the control system, an engine 100 and a motor generator 1 are used as power sources, and respective powers are appropriately transmitted to wheels 4 via a clutch 2 and a transmission 3.
[0018]
A hybrid control unit (HCU) 5, which is an embodiment of a vehicle control device, starts and stops the hybrid vehicle system based on a signal from an ignition key switch 6, and is required in response to operation signals of an accelerator 7 and a brake 8 by a driver. In order to apply an appropriate torque to the wheels 4, predetermined commands are output to an engine control unit (ECU) 9, an inverter 10 for controlling the motor generator 1, and the clutch 2.
[0019]
The electric energy from the battery 11 is converted into an alternating current by the inverter 10 and applied to the motor generator 1. The generated driving force drives the output shaft 25 and the wheels 4 when starting the engine 100 via the belt 12. Drive. The battery 11 is different from a 12 V battery which is a power supply of the HCU 5 or the like, and is a 42 V battery in the present embodiment. The motor 11 rotates the motor generator 1 by the kinetic energy of the wheels 4 or the driving force of the engine 100. To generate electric power, which is converted into a direct current by the inverter 10 and then charged.
[0020]
The engine 100 is controlled by the ECU 9, and the ECU 9 instructs the throttle opening control device 14 on the rotation speed of the engine 100 and the target opening of the throttle 13 obtained from the torque command of the HCU 5 to control the air flow rate. Further, the ECU 9 controls the fuel injection width of the fuel injection device 17 based on the engine cooling water temperature detected by the water temperature sensor 15, the detection signal of the oxygen concentration sensor 16 disposed on the exhaust side, and the like. The mixture of fuel and air is drawn into the cylinder 19 from the intake valve 18 and ignited by the ignition device 20. Then, the piston 21 is moved by the explosion energy, and the wheels 4 and the motor generator 1 are driven via the output shaft 25.
[0021]
The combustion gas in the cylinder 19 is exhausted from the exhaust valve 22 to the exhaust side, is purified by a catalyst 23 which is an embodiment of an exhaust purification device, and is then released to the atmosphere. A temperature sensor 24 for detecting a catalyst temperature is provided at an appropriate position of the catalyst 23, and this signal is also output to the ECU 9.
[0022]
FIG. 2 is a control block diagram of the HCU 5.
There are the following four types of operation modes of the hybrid vehicle system of the present embodiment.
The first is the engine start mode. In this mode, the maximum torque command is given to the inverter 10 of the motor generator 1 to rotate the output shaft 25 of the engine 100, and when the engine speed reaches 900 r / min, the fuel injection prohibition command to the ECU 9 is released. The engine 100 is started by supplying fuel from the fuel injection valve 17 to the cylinder 19. Since the output of the motor generator 1 is larger than that of the conventional starter, the rotation speed at which the fuel injection prohibition command is canceled can be set higher than about 200 r / min of a gasoline vehicle.
[0023]
Second is the idle stop mode. In this mode, the brake 8 is depressed with the wheels 4 stopped, the accelerator 7 is released, and there is no need for creep. In addition, the temperature of the catalyst 23 detected by the temperature sensor 24 is high, and the catalyst 23 is activated. In this case, the supply of fuel from the fuel injection valve 17 to the cylinder 19 is stopped, and the engine 100 is stopped so that the fuel is not consumed. As will be described later, the drive time of the output shaft 25 that is motored after the engine 100 is stopped is determined based on the temperature of the catalyst 23 when the engine stop command is output. For example, as the temperature of the catalyst 23 is lower, the time for motoring after the engine 100 is stopped is set shorter to prevent inactivation due to lowering of the temperature of the catalyst 23 due to the motoring.
[0024]
Third is the catalyst activation mode. In this mode, the brake 8 is depressed when the wheels 4 are stopped, the accelerator 7 is released, and there is no need for creep. However, when the temperature of the catalyst 23 is low, the cylinder 19 is controlled so as not to enter the idle stop mode. And the catalyst 23 is heated by the burned exhaust gas. In addition to the idling, it is also possible to apply a load to the engine 100 from the motor generator 1 to further heat the temperature of the catalyst 23.
[0025]
Fourthly, it is a traveling / power generation mode, which is a case of normal operation which does not correspond to any of the above three modes. In this mode, the brake 8 is released even when the vehicle is running or stopped, and the vehicle runs or generates power using the engine 100 as a power source.
[0026]
The HCU 5 is configured to operate the engine based on operation signals of the key switch 6, the accelerator 7, the brake 8, etc., the rotational speed of the motor generator 1, the input / output power of the battery 11, the engine rotational speed and the temperature of the catalyst 23. 100, an engine start control means 51 for controlling the motor generator 1 or the engine 100 in the engine start mode based on the operation mode judgment, and a motor in the idle stop mode. An idle stop control unit 52 for controlling the generator 1, a catalyst activation control unit 53 for controlling the engine 100 in the catalyst activation mode, and a traveling power generation control unit 54 for controlling the engine 100 in the traveling / power generation mode; The supply of fuel from the fuel injection valve 17 to the cylinder 19 is stopped It is, when the idling is stopped, and a drive instruction means 55 for giving a drive instruction of the output shaft 25 to the motor-generator 1.
Then, in the drive command means 55, the output value P of the drive command of the output shaft 25 is obtained by the following equation (1).
[0027]
(Equation 1)
P = k × T × N (1)
[0028]
Here, T is the motor drive time of the motor generator 1, N is the motor speed, and k is a constant, and the motor drive time or the motor speed is equal to the drive time or the speed of the output shaft 25, respectively. That is, the drive command means 55 outputs to the motor generator 1 an output value P of a drive command substantially proportional to the product of the rotation speed N of the output shaft 25 and the drive time T, and performs pumping of the cylinder 19.
[0029]
Then, as described above, the drive command means 55 is to provide the motor generator 1 with an appropriate drive command for the output shaft 25 when the supply of fuel to the cylinder 19 is stopped after the wheels 4 are stopped. , A rotation speed correction unit 551 for correcting the rotation speed of the output shaft 25, and a drive time correction unit 552 for correcting the drive time of the output shaft 25. The rotation speed N or the drive time T is corrected based on the above, and the corrected output value P of the drive command is output to the inverter 10 to drive the motor generator 1. For example, when the rotation speed N is high, the driving time T is shortened, while when the rotation speed N is low, the driving time T is lengthened.
[0030]
FIG. 3 is an operation flowchart of the HCU 5, and this process is executed every 10 ms.
In step 101, operation signals of the key switch 6, the accelerator 7, and the brake 8 are input. In step 102, data such as a torque command and a fuel injection prohibition command are transmitted to the ECU 9 and the inverter 10, and the number of revolutions of the motor generator 1 and the input / output power of the battery 11 are received from the inverter 10. The program proceeds to step 103 after receiving the engine speed and the temperature of the catalyst 23.
[0031]
In step 103, an appropriate operation mode is selected from the above-described four system operation modes based on the operation signal, the input / output available power, the number of revolutions, and the catalyst temperature by the operation mode determination means 50.
That is, in step 104, it is determined whether or not the engine is in the first engine start mode. If the engine is in the engine start mode, that is, if YES, the process proceeds to step 105, and the engine start control means 51 sets the engine start mode. The processing is performed and a series of operations is completed.
[0032]
If the engine is not in the engine start mode in step 104, the process proceeds to step 106, where it is determined whether or not the second idle stop mode is set. If the mode is the idle stop mode, that is, if YES, the process proceeds to step 107 and the idle stop control means The processing in the idle stop mode is performed by the drive commanding means 52 and the drive command means 55, and a series of operations is completed. That is, the stop of the fuel supply to the cylinder 19 from the idle stop control means 52 is output to the drive command means 55, and when the wheels 4 are stopped and the fuel cut is commanded to the engine 100, the drive command of the output shaft 25 is issued. Is output to the motor generator 1 via the inverter 10 to pump the engine 100 for a predetermined period.
[0033]
If it is not the idling stop mode in step 106, the process proceeds to step 108, where it is determined whether or not the third catalyst activation mode is set. If it is the catalyst activation mode, that is, if YES, the process proceeds to step 109, At 53, the process in the catalyst activation mode is performed, and a series of operations is completed.
[0034]
If it is determined in step 108 that the current mode is not the catalyst activation mode, the process proceeds to step 110, in which the traveling / power generation control unit 54 performs the fourth traveling / power generation mode. That is, in step 110, the target torque TO is determined from the opening degree of the accelerator 7 and the engine speed, and in step 111, the target drive torque TMO of the motor generator 1 is obtained from the available output power of the battery 11, and the target drive TO for the target torque TO is determined. The shortage of the torque TMO is output to the ECU 9 as the target drive torque TEO of the engine, and a series of operations is ended.
Engine 100 is controlled by a command issued by ECU 9 based on a command given from HCU 5.
[0035]
FIG. 4 is an operation flowchart of the ECU 9, and this process is also executed every 10 ms.
In step 201, signals of the water temperature sensor 15, the oxygen concentration sensor 16 provided in the exhaust pipe, and the catalyst temperature sensor 24 are input. In step 202, data such as an engine torque command and a fuel injection prohibition command received by data communication with the HCU 5 is fetched, and transmission data such as an engine speed is set. In step 203, the target opening of the throttle 13 for controlling the air flow is obtained from the detected engine speed and the given target driving torque TEO, and is output to the throttle control device 14. In step 204, the target fuel injection pulse width is calculated. At this time, if the fuel injection prohibition command has been issued, the target injection pulse width is set to zero. The control of the fuel injection device 17 according to the target injection pulse width is performed by another interrupt process. Then, in step 205, the operation and calculation of the opening / closing timing of the intake valve 18 and the exhaust valve 22 are performed, and the operation ends.
As described above, the embodiment of the present invention has the following functions by the above configuration.
[0036]
That is, the HCU 5 according to the present embodiment includes an idle stop control unit 52 that controls the motor generator 1 in the idle stop mode, and a stop of the supply of fuel from the fuel injection valve 17 to the cylinder 19 from the idle stop control unit 52. A drive command means 55 for giving a drive command of the output shaft 25 to the motor generator 1 when the output is outputted. The drive command means 55 controls the rotation speed by the motor generator 1 even after the fuel supply to the cylinder 19 is stopped. Since the engine 100 is pumped by motoring, air and exhaust gas containing oxygen can be sent from the inside of the cylinder 19 to the activated catalyst 23, so that the throttle 13 when the engine 100 is stopped Exhaust gas is scavenged to eliminate oxygen deficiency at restart, It is possible to improve the resistance. In addition, the drive command unit 55 calculates the output value P of the drive command of the output shaft 25 via the rotation speed correction unit 551 or the drive time correction unit 552 based on the temperature of the catalyst 23. Motoring can be performed appropriately according to the conditions.
[0037]
As described above, one embodiment of the present invention has been described in detail, but the present invention is not limited to the above embodiment, and various changes in design may be made without departing from the spirit of the invention described in the claims. You can do it.
[0038]
For example, the drive command means 55 sets the output value P of the drive command of the output shaft 25 based on the temperature of the catalyst 23 as the state detection amount of the exhaust purification device. The output value P of the drive command may be set based on the water temperature, and the same effect as described above can be obtained. For example, a correction may be made to reduce the time for driving the motor generator 1 and motoring the engine 100 as the cooling water temperature is lower.
[0039]
The HCU 5 of the present embodiment stops the engine 100 after the wheels 4 stop. However, the HCU 5 can stop the engine immediately before the wheels 4 stop. Since the cylinder can be pumped by rotation from the side, the correction value proportional to the time integral value of the engine speed after the fuel cut is subtracted from the motoring time by the motor generator, shorten the motoring time, and then output the drive command. A value may be set.
[0040]
【The invention's effect】
As can be understood from the above description, the control device for a vehicle according to the present invention provides a combined system of an engine and a motor generator, in which the engine is stopped after the wheels stop, to pump air containing oxygen and exhaust gas by the motor generator. Therefore, the exhaust gas is sent to the warmed catalyst and purified, so that the exhaust gas performance at the time of restarting the engine can be improved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a control system including a vehicle control device according to an embodiment.
FIG. 2 is a control block diagram of the vehicle control device of FIG. 1;
FIG. 3 is an operation flowchart of the control device for the vehicle in FIG. 1;
FIG. 4 is an operation flowchart of the control device for an internal combustion engine of FIG. 1;
FIG. 5 is a diagram showing the flow of exhaust gas when the start and stop of the internal combustion engine are frequently repeated.
[Explanation of symbols]
1 motor generator 4 wheels 5 vehicle control unit (HCU)
23 Exhaust gas purification device (catalyst)
25 Output Shaft 50 Means for Determining Operating Mode 51 Means for Controlling when Internal Engine Starts 52 Means for Controlling when Fuel Supply is Stopped 53 Means for Controlling Exhaust Purification Device 54 Means for Controlling During Normal Running 55 Means for Commanding Drive of Internal Combustion Engine 551 Means for correcting rotation speed of internal combustion engine 552 Means for correcting drive time of internal combustion engine 100 Internal combustion engine

Claims (4)

In a control device for a vehicle including an internal combustion engine and a motor generator that drives the internal combustion engine, the control device includes a drive command unit,
The drive instructing means scavenges exhaust gas in the internal combustion engine when the supply of fuel to the internal combustion engine is stopped after the vehicle is stopped and the rotation of the internal combustion engine is stopped. to a predetermined drive time at a predetermined rotation speed, it has rows a drive command to drive the internal combustion engine by said motor generator,
The drive command means includes means for correcting the rotation speed of the internal combustion engine and means for correcting the drive time of the internal combustion engine,
The means for correcting the number of revolutions of the internal combustion engine or the means for correcting the driving time of the internal combustion engine corrects the number of revolutions based on a state detection amount of the exhaust gas purification device of the internal combustion engine or the driving of the internal combustion engine. A vehicle control device for correcting time . The control device for a vehicle according to claim 1, wherein the state detection of the exhaust gas purification device of the internal combustion engine detects a temperature of the exhaust gas purification device. Wherein the state detection of the exhaust gas purifying apparatus for an internal combustion engine, the control apparatus for a vehicle according to claim 1, characterized in that for detecting the temperature of cooling water of the internal combustion engine. The control device includes: means for determining an operation mode of the internal combustion engine; means for controlling the motor generator or the internal combustion engine when the internal combustion engine is started based on the operation mode; and Means for controlling the motor generator when supply is stopped, means for controlling the exhaust gas purification device of the internal combustion engine, and means for controlling the internal combustion engine when the vehicle is running and generating electric power, and the drive command means includes: 4. The motor generator according to claim 1, wherein a drive command for the internal combustion engine is given to the motor generator in accordance with an output signal from a means for controlling the motor generator when supply of fuel to the internal combustion engine is stopped. 5 . A control device for a vehicle according to any one of the preceding claims.

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