JP2005042566A - Power control method for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress response delay to a request for acceleration by a driver and relieve start shock by the sudden rise of a torque caused when an internal combustion engine is re-started after a vehicle is stopped in a method for controllably stopping the idling of the internal combustion engine before stopping the vehicle and controllably re-starting the internal combustion engine from an idling stop state with a transmission brought into a running state. <P>SOLUTION: In this method, the idling of the internal combustion engine is controllably stopped before the vehicle is stopped, and with the transmission brought into a running state, the internal combustion engine is re-started from the stop of the idling. Before the vehicle is stopped, the rise rate r2 of the engine speed when the internal combustion engine is re-started is controlled high. When the internal combustion engine is re-started after the vehicle is stopped, the internal combustion engine is started at the rise rate r1 of the engine speed which is lower than the rise rate r2 of the engine rotational speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle power control method at the time of restart in a vehicle that performs control for stopping idling of an internal combustion engine before the vehicle stops.
[0002]
[Prior art]
Conventionally, as a method of improving fuel consumption in a vehicle equipped with an internal combustion engine, the internal combustion engine can be used when an automatic engine stop condition is satisfied while the vehicle is running, such as when the throttle valve is fully closed for a predetermined time. It is considered to perform control to stop the idling (see, for example, Patent Document 1).
[0003]
In addition, when a so-called hybrid vehicle equipped with an internal combustion engine and an electric motor is restarted, when the accelerator pedal is greatly depressed, it is based on the amount of operation of the accelerator pedal in order to complete the start in a short time in response to the acceleration request. It is also considered to determine the starting speed (see, for example, Patent Document 2).
[0004]
[Patent Document 1]
JP-A-8-189395 [Patent Document 2]
JP 2000-204999 A
[Problems to be solved by the invention]
By the way, in the hybrid vehicle, when the configuration as in Patent Document 1 is applied to an engine that is started by an electric motor, if the automatic stop condition is not satisfied because the accelerator pedal is depressed before the vehicle stops, or the like. The engine is restarted. At this time, if the rate of increase in the rotational speed of the electric motor is low, the start of the engine is delayed, and a response delay to the start request by the driver occurs.
[0006]
Therefore, as in Patent Document 2, when the activation speed is determined based on the operation amount of the speed control means, the activation speed, that is, the rate of increase in the rotation speed increases when the operation amount of the speed control means is large. The above-mentioned response delay problem can be solved. However, when the rate of increase in the rotational speed is increased, a start shock occurs due to a sudden increase in torque while the transmission is configured to be able to run when the power mechanism is restarted from when the vehicle stops during running. This may cause a problem that makes the driver feel uncomfortable.
[0007]
The present invention solves the above-described problems, and controls an internal combustion engine that alleviates a start shock caused by a sudden increase in torque when a power mechanism is restarted from a stop while suppressing a delay in response to an acceleration request by a driver. A method is provided.
[0008]
[Means for Solving the Problems]
That is, the vehicle power control method according to the present invention performs control to stop idling of the internal combustion engine before the vehicle stops and performs control to restart the internal combustion engine from idling stop while the transmission is configured to be able to run. The engine speed increase rate when the internal combustion engine is restarted before the vehicle stops is controlled to be high, and when the internal combustion engine is restarted after the vehicle stops, the engine speed increase rate The internal combustion engine is started at a lower engine speed increase rate.
[0009]
By adopting such a control method, the engine speed increase rate when the internal combustion engine is restarted before the vehicle stops is set high to suppress a delay in response to the start request by the driver, and the vehicle When the internal combustion engine is restarted after being stopped, the start shock as described above can be mitigated by starting the internal combustion engine at an engine speed increase rate lower than the engine speed increase rate.
[0010]
Note that “to configure the transmission in a state where it can travel” is a concept that includes making the transmission in a state other than the so-called neutral state.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0012]
The vehicle according to the present embodiment uses a hybrid vehicle power mechanism (hereinafter abbreviated as a power mechanism) PP shown in FIG. The power mechanism PP includes a four-cylinder gasoline engine (hereinafter simply referred to as an engine) 1 that is an internal combustion engine, a transmission 2 that changes the speed of the engine 1, and a three-phase AC motor 3 that is an electric rotary machine. It comprises. In this embodiment, a configuration in which the electric motor 3 is disposed between the engine 1 and the transmission 2 is adopted, and the engine 1 is stopped without idling while the vehicle is stopped in order to improve fuel consumption. I am doing so. The electric motor 3 functions as a starter when starting the engine 1 that stops in this way, and also functions as a generator by regenerating with the driving force from the wheels when the vehicle is in a decelerating state. is there. The engine 1, the transmission 2, the electric motor 3, and a drive device (not shown) for running the vehicle are mechanically connected. The engine 1, the transmission 2, and the electric motor 3 are controlled by the electronic control unit 4 shown in FIG.
[0013]
The electronic control device 4 is mainly configured by a microcomputer system including a central processing unit 41, a storage device 42, an input interface 43, and an output interface 44. In the input interface 43 of the electronic control unit 4, an intake pressure signal corresponding to the pressure in the surge tank (intake pipe pressure) for detecting data necessary for controlling the engine 1, an engine speed NE, for example, is detected. A corresponding rotation speed signal, a cam position signal according to the crank angle, a required acceleration signal d indicating the depression amount of the accelerator pedal 6 as speed control means, a water temperature signal according to the cooling water temperature of the engine 1, and O ₂ inside the engine 1. The air-fuel ratio signal output from the sensor, the current and voltage signal for detecting the remaining battery capacity, the starter current and voltage signal for detecting the current and voltage supplied to the motor 3, and the motor 3 are generated. A power signal for detecting generated power when functioning as a machine, a speed detection signal v corresponding to the speed of the vehicle output from the speed detector 5, and a throttle bar An idling detection signal x for detecting whether or not the lub is in a fully closed state is input. On the other hand, from the output interface 44, a fuel injection signal is given to each fuel injection valve of the engine 1, an ignition signal is given to the spark plug of each cylinder, and the motor 3 shows the rate of increase in the number of revolutions at the time of start. The rotational speed increase rate signal r and the like are individually output at a predetermined timing.
[0014]
The electronic control unit 4 incorporates a program for performing control to stop the operation of the engine 1 before the vehicle stops, that is, before the vehicle traveling speed indicated by the speed detection signal v becomes zero.
[0015]
The general procedure of this control program will be described with reference to FIG.
[0016]
First, in step ST11, it is determined whether or not a state in which a throttle valve (not shown) provided in the engine 1 is fully closed continues for a predetermined time. Detection of the state where the throttle valve is fully closed is performed by an idling detection signal x. If it is determined in step ST11 that the throttle valve is fully closed for a predetermined time, the process proceeds to step ST12. On the other hand, if not, the control program is terminated.
[0017]
Next, in step ST12, it is determined whether or not the brake pedal is depressed. If it is determined in step ST12 that the brake pedal is depressed, the process proceeds to step ST13. On the other hand, if not, the control program is terminated.
[0018]
In step ST13, control is performed to stop idling of the engine 1 by stopping the supply of fuel while the transmission 2 is configured to be able to travel. Specifically, control for stopping the output of a drive pulse as a fuel injection signal to a fuel injection valve (not shown) in the engine 1 is performed.
[0019]
When the control is performed in this manner, the state where the throttle valve is fully closed continues for a predetermined time, and when the brake pedal is depressed, the fuel injection is stopped, so that the fuel consumption is improved. You can plan.
In addition, the electronic control unit 4 is configured so that the transmission 2 can travel when the engine 1 is restarted, for example, at the time of reacceleration or starting, and the engine 1 is based on the operation amount of the accelerator pedal 6, that is, the depression amount. A program for determining the engine speed at the time of restart, that is, the rate of increase in the speed of the motor 3 is also incorporated.
[0020]
Thus, after the vehicle stops, that is, when the traveling speed of the vehicle indicated by the speed detection signal v is 0, the rotational speed increase rate r1 of the electric motor 3 when the engine 1 is restarted is determined until the vehicle stops. That is, the accelerator pedal 6 indicated by the required acceleration signal d is compared with the motor speed increase rate r2 when the engine 1 is restarted when the vehicle speed indicated by the speed detection signal v is not zero. When the amount of stepping is the same, it is lowered.
[0021]
Specifically, after the vehicle has stopped, that is, when the traveling speed of the vehicle indicated by the speed detection signal v is 0, the first increase rate r1 is set with the amount of depression of the accelerator pedal 6 as a parameter. The engine speed increase rate r2 is set with the amount of depression of the accelerator pedal 6 as a parameter until the vehicle stops, that is, when the vehicle traveling speed indicated by the speed detection signal v is not zero. The electronic control unit 4 includes a second rotation speed increase rate table. In these first and second rotation speed increase rate tables, rotation speed increase rates r1 and r2 are set with respect to a typical depression amount of the accelerator pedal 6, and rotations with respect to other depression amounts of the accelerator pedal 6 are set. The number increase rates r1 and r2 are calculated by interpolation calculation.
[0022]
The general procedure of this control program will be described with reference to FIG. 3 which is a flowchart.
[0023]
First, in step ST21, the amount of depression of the accelerator pedal 6 indicated by the required acceleration signal d is acquired.
[0024]
Next, in step ST22, it is determined whether or not the amount of depression of the accelerator pedal 6 is zero. If it is determined in step ST22 that the amount of depression of the accelerator pedal 6 is zero, this control program is terminated. On the other hand, if not, the process proceeds to step ST23.
[0025]
In step ST23, it is determined whether or not the vehicle traveling speed is zero. If it is determined in step ST23 that the vehicle traveling speed is 0, the process proceeds to step ST24. On the other hand, if not, the process proceeds to step ST25.
[0026]
In step ST24, the amount of depression of the accelerator pedal 6 acquired in step ST21 is used as a parameter, and the rotational speed increase rate r1 of the electric motor 3 is calculated with reference to the first rotational speed increase rate table. Then, the process proceeds to step ST26.
[0027]
In step ST25, the amount of depression of the accelerator pedal 6 acquired in step ST21 is used as a parameter, and the rotation speed increase rate r2 of the electric motor 3 is calculated with reference to the second rotation speed increase rate table. Then, the process proceeds to step ST26.
[0028]
In step ST26, a rotation speed increase rate signal r corresponding to the calculated rotation speed increase rates r1 and r2 is output to the electric motor 3, and control for increasing the rotation speed of the electric motor 3 is performed.
[0029]
When the engine 1 is restarted before the vehicle stops, the control is performed in the order of steps ST21 → ST22 → ST23 → ST25 → ST26, and the electric motor 3 is referred to by referring to the second rotation speed increase rate table. The rotation speed increase rate r2 is calculated, and the rotation speed of the electric motor 3 increases at the rotation speed increase rate r2. On the other hand, when the engine 1 is restarted after the vehicle stops, the control is performed in the order of steps ST21 → ST22 → ST23 → ST24 → ST26, and the electric motor 3 is referred to by referring to the first rotation speed increase rate table. The rotational speed increase rate r1 is calculated, and the rotational speed of the electric motor 3 increases at the rotational speed increase rate r1.
[0030]
Hereinafter, the operation when such control is performed will be described with reference to FIGS. FIG. 4A shows a common time axis representing changes over time in the rotational speed of the motor 3, the torque of the motor 3, and the torque of the axle when the engine 1 is restarted before the vehicle stops. Is shown. (B) of the figure shows the time change of the rotation speed of the electric motor 3, the torque of the electric motor 3, and the torque of the axle when the engine 1 is restarted after the vehicle stops with respect to the common time axis. Is. On the other hand, FIG. 5 shows the time change of the rotational speed of the motor 3 at the time of restart when the depression amount of the accelerator pedal 6 is the same predetermined value when the rotational speed increase rate is r1 and the rotational speed increase rate is r2. Are shown with respect to a common time axis.
[0031]
When the engine 1 is restarted at the rotational speed increase rate r2 of the electric motor 3 until the vehicle stops, the rotational speed of the electric motor 3, the torque of the electric motor 3, and the torque of the axle are shown in FIG. It will change as shown in. That is, as shown in the time zone T11 of FIG. 4A, the rotational speed of the electric motor 3 rapidly increases while the engine 1 is cranked immediately after starting. At this time, the output torque of the electric motor 3 also rapidly increases. Next, as shown in the time zone T12 of FIG. 4A, when the engine 1 completes explosion and starts rotating, the rotation speed of the motor 3 increases in accordance with the rotation speed of the engine 1, but the output of the motor 3 The torque decreases to a value commensurate with the rotational speed of the engine 1. Thereafter, the output torque of the electric motor 3 changes substantially in synchronization with the rotational speed of the engine 1. Here, since the engine 1 is restarted in a state where the vehicle is not completely stopped, the torque of the electric motor 3 is received while the wheels are slightly rotated. Therefore, the fluctuation of the torque received by the axle is relatively small even when the rotation rate increase rate of the electric motor 3 is high, the torque reaction force from the wheel received by the axle is also small, and the starting shock received by the driver is also relatively small. Become.
[0032]
On the other hand, when the engine 1 is restarted after the vehicle stops, the rotational speed of the electric motor 3, the torque of the electric motor 3, and the torque of the axle change as shown in FIG. Here, the case where the rotation speed increase rate of the electric motor 3 is r1 (<r2) is indicated by a solid line, and the case where the rotation speed increase rate of the electric motor 3 is r2 is indicated by a broken line. That is, when the rate of increase in the rotational speed of the electric motor 3 is r2, as in the case where the engine 1 is restarted before the vehicle is stopped, the engine 1 is cranked immediately after starting. As indicated by the broken line in the time zone T21 in FIG. 4B, the rotational speed of the electric motor 3 rapidly increases while the engine 1 is cranked immediately after starting. At this time, the output torque of the electric motor 3 also rapidly increases. Next, as indicated by the broken line in the time zone T22 of FIG. 4B, the rotational speed of the electric motor 3 increases in accordance with the rotational speed of the engine 1, but the output torque of the electric motor 3 matches the rotational speed of the engine 1. Decrease to the value. Thereafter, the output torque of the electric motor 3 changes substantially in synchronization with the rotational speed of the engine 1. At this time, since the torque of the electric motor 3 is received in a state where the rotation of the wheels is stopped, the torque fluctuation received by the axle is restarted of the engine 1 until the vehicle stops, that is, before the vehicle stops. Compared with the case where the vehicle is operated, the torque reaction force from the wheels received by the axle and the start shock received by the driver are increased. However, in actuality, as described above, the rate of increase in the rotational speed of the electric motor 3 is set to r1, and the rotational speed of the electric motor 3 is stopped before the vehicle stops as shown in the solid line in FIG. 4B and the aforementioned FIG. Compared with the case where the engine 1 is restarted, the engine 1 is gradually raised over time. Therefore, both the increase in the output torque of the electric motor 3 during cranking of the engine 1 immediately after start-up and the decrease in the output torque of the electric motor 3 immediately after the engine 1 starts to rotate completely are started. As shown by the solid line in FIG. 4B, the output torque of the axle does not decrease. That is, there is almost no torque reaction force from the wheels received by the axle and no starting shock received by the driver.
[0033]
By performing the control as described above, the following effects can be obtained.
[0034]
In other words, the speed increase rate r2 when the vehicle is restarted before the vehicle stops can be set higher to suppress a delay in response to the acceleration request by the driver, and the vehicle is restarted after the vehicle stops. In the case, the same accelerator pedal as in the case of restarting the rotational speed increase rate r1 of the electric motor 3 obtained by using the depression amount of the accelerator pedal 6 indicated by the required acceleration signal d as a parameter before the vehicle stops. 6 can be made lower than the speed increase rate r2 of the electric motor 3, which is obtained as a parameter, and the starting shock when starting after stopping the vehicle can be reduced.
[0035]
The present invention is not limited to the embodiment described above.
[0036]
For example, in the above-described embodiment, the present invention is applied to the control of the rate of increase in the rotational speed of the electric motor at the start of the hybrid power vehicle. You may make it perform control of the rotation speed increase rate at the time of restart of a starter similarly to control of the rotation speed increase rate of the electric motor in embodiment mentioned above.
[0037]
In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
[0038]
【The invention's effect】
When the control method for an internal combustion engine according to the present invention is adopted, it is possible to suppress a response delay to an acceleration request by a driver by setting a high rate of increase in the number of revolutions when the internal combustion engine is restarted before the vehicle stops. In addition, the engine speed increase rate when the internal combustion engine is restarted after the vehicle is stopped is set lower than the engine speed increase rate when the internal combustion engine is restarted before the vehicle stops. Therefore, when the internal combustion engine is restarted after the vehicle stops, it is possible to mitigate a start shock due to a sudden increase in torque.
[Brief description of the drawings]
FIG. 1 is a schematic view of a power mechanism and an electronic control device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing processing performed by the control device according to the embodiment;
FIG. 3 is a flowchart showing processing performed by the control device according to the embodiment;
FIG. 4 is a diagram showing an operation of control in FIG. 3;
FIG. 5 is a diagram showing an operation of control in FIG. 3;
[Explanation of symbols]
1. Engine (internal combustion engine)
2. Transmission 4 ... Electronic control unit

Claims (1)

In what performs control to stop idling of the internal combustion engine before stopping the vehicle and performs control to restart the internal combustion engine from idling stop while the transmission is configured to be able to travel,
When the internal combustion engine is restarted before the vehicle stops, the engine speed increase rate is controlled to be high. When the internal combustion engine is restarted after the vehicle stops, the engine speed is lower than the engine speed increase rate. A power control method for a vehicle, wherein the internal combustion engine is started at a rate of increase in number.

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