JP6041573B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device equipped with an idle stop function.

  In recent years, some vehicles using an engine as a drive source are equipped with a so-called idle stop function in order to suppress wasteful fuel consumption and exhaust gas emission. With the idle stop function, while the ignition key switch (start switch) of the vehicle is turned on, the engine is automatically stopped in response to establishment of a predetermined stop condition, and the engine is automatically restarted in response to establishment of a predetermined restart condition. The start is repeated.

  The stop condition includes a condition that the brake pedal is depressed and the vehicle speed is 0 km / h. Under this stop condition, the engine is automatically stopped after the brake pedal is depressed and the vehicle is stopped.

  As another stop condition, there is a condition that the brake pedal is depressed and the vehicle speed is reduced to a predetermined vehicle speed (for example, 7 km / h) or less. Under this stop condition, the engine is automatically stopped while the vehicle is traveling (before stopping). Therefore, compared with the previous stop condition, the time during which the engine is stopped (idle stop) can be extended, so that the fuel consumption can be further improved.

JP 2012-76520 A

  However, when the driver is stepping on the brake pedal with a relatively small pedaling force, if the engine is automatically stopped and the driving force of the engine is lost, the braking force by the service brake is changed to be relatively weak and the driver decelerates. There is a risk of giving a feeling of incongruity due to an increase in deceleration.

  An object of the present invention is to provide a vehicle control device that can prevent a driver from feeling a sense of deceleration due to an automatic stop of a running engine.

  In order to achieve the above-mentioned object, the vehicle control device according to the present invention has said that the brake of the vehicle is actuated while the drive source of the vehicle is being driven, and the vehicle speed is reduced to a predetermined vehicle speed greater than 0 km / h. In response to the establishment of a predetermined stop condition including a condition, an idle stop means for automatically stopping the drive source, and when the stop condition is satisfied and the drive source is automatically stopped by the idle stop means And a reducing means for reducing the braking force by the brake.

  According to this configuration, when the vehicle brake is actuated during driving of the vehicle drive source and a predetermined stop condition is satisfied, the drive source is automatically stopped. The stop condition includes a condition that the vehicle speed has decreased to a predetermined vehicle speed greater than 0 km / h. When the drive source is automatically stopped, the braking force by the brake is reduced.

  When the braking force by the brake is constant, the deceleration of the vehicle increases with the automatic stop of the drive source. When the driving source is automatically stopped, the braking force by the brake is reduced, so that the change in the deceleration accompanying the automatic stopping of the driving source can be suppressed. As a result, it is possible to prevent the driver from feeling slowed down.

  It is preferable that the deceleration of the vehicle is detected, and the braking force by the brake is reduced by a reduction range corresponding to the detected deceleration.

  For example, as the deceleration increases, the braking force by the brake is reduced by a large reduction range, so that the deceleration change accompanying the automatic stop of the drive source is better while securing the necessary and sufficient deceleration for stopping the vehicle. Can be suppressed. As a result, the vehicle can be satisfactorily stopped while further preventing the driver from feeling of deceleration.

  According to the present invention, when the drive source is automatically stopped, the braking force by the brake is reduced, so that it is possible to suppress the change in the deceleration accompanying the automatic stop of the drive source. As a result, it is possible to prevent the driver from feeling slowed down.

FIG. 1 is a block diagram showing a configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. FIG. 2 is a timing chart for explaining the wheel cylinder pressure control. FIG. 3 is a graph showing the relationship between deceleration and wheel cylinder pressure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Overall configuration of vehicle>

  FIG. 1 is a block diagram showing a configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention.

  The vehicle 1 is an automobile that uses the engine 2 as a drive source.

The output of the engine 2 includes a torque converter 3 and a continuously variable transmission (CVT: Continuously
It is transmitted to driving wheels (for example, left and right front wheels) of the vehicle 1 via a variable transmission 4.

  A starter (starting motor) 5 is provided along with the engine 2. The stopped engine 2 starts after cranking by the starter 5.

  An alternator 6 is provided in association with the engine 2.

  The rotation of the output shaft of the engine 2 is transmitted to the rotation shaft (rotor) of the alternator 6. When the rotating shaft of the alternator 6 rotates, the rotation is converted into electric power, and electric power is output from the alternator 6.

  Each wheel of the vehicle 1 (for example, left and right front wheels and rear wheels) is provided with a brake 7. A brake pedal 8 that is operated by a driver's foot is provided in the vehicle interior of the vehicle 1. The brake pedal 8 is connected to a brake booster 10 provided integrally with the master cylinder 9.

  When the brake pedal 8 is depressed, the pedal force input to the brake pedal 8 is transmitted to the brake booster 10. The pedaling force transmitted to the brake booster 10 is amplified (boosted) by the negative pressure of the brake booster 10 and input from the brake booster 10 to the master cylinder 9. In the master cylinder 9, a hydraulic pressure corresponding to the force input from the brake booster 10 is generated.

  The hydraulic pressure in the master cylinder 9 is transmitted to the brake actuator 11. The brake actuator 11 incorporates a valve for controlling the hydraulic pressure of the wheel cylinder provided in the brake 7 of each wheel, a pump for returning the brake fluid to the master cylinder 9, and the like. The hydraulic pressure transmitted from the master cylinder 9 to the brake actuator 11 is distributed and transmitted to the wheel cylinder of each brake 7. A braking force is applied from the brake 7 to the wheel by the hydraulic pressure of the wheel cylinder.

  The vehicle 1 is further provided with a battery 12.

  The battery 12 is charged with electric power output from the alternator 6. A starter 5 and the like are electrically connected to the battery 12. Drive power is supplied from the battery 12 to the starter 5. A relay 13 is interposed on the power supply path from the battery 12 to the starter 5.

  The vehicle 1 is also provided with a plurality of ECUs (electronic control units) having a configuration including a CPU and a memory (ROM, RAM, etc.). The ECU includes an engine ECU 21, a CVT (Continuously Variable Transmission) ECU 22, a brake ECU 23, and an idle stop ECU 24. The engine ECU 21, the CVTECU 22, the brake ECU 23, and the idle stop ECU 24 can communicate with each other using a CAN (Controller Area Network) communication protocol.

  The engine 2 is connected to the engine ECU 21 as a control target.

  The CVT ECU 22 is connected to the continuously variable transmission 4 as a control target.

  The brake actuator 11 is connected to the brake ECU 23 as a control target.

  The brake ECU 23 includes a wheel speed sensor 25 that detects the rotational speed (wheel speed) of each wheel, a G sensor 26 that detects the acceleration of the vehicle 1, a brake negative pressure sensor 27 that detects the negative pressure of the brake booster 10, A master cylinder pressure sensor 28 for detecting the hydraulic pressure of the master cylinder 9 and a wheel cylinder pressure sensor 29 for detecting the hydraulic pressure of the wheel cylinder of each brake 7 are connected.

  The brake ECU 23 calculates the average value of the wheel speeds based on the detection signal input from the wheel speed sensor 25, and calculates the vehicle speed (body speed) of the vehicle 1 from the average value. Further, the brake ECU 23 controls the engine ECU 21 to control the rotational speed of the engine 2 based on the detection signal input from the brake negative pressure sensor 27 so that the negative pressure of the brake booster 10 becomes a suitable negative pressure. Send a command.

  The relay 13 is connected to the idle stop ECU 24 as a control target. The vehicle 1 has an idle stop function, and the idle stop ECU 24 executes control for the idle stop function (idle stop control). For idle stop control, information such as the engine speed is input from the engine ECU 21 to the idle stop ECU 24, and the vehicle speed and the hydraulic pressure of the master cylinder 9 are input from the brake ECU 23.

  In the idle stop control, while the engine 2 is being driven, the idle stop ECU 24 repeatedly determines whether or not a predetermined stop condition is satisfied. The stop condition is that the brake pedal 8 is depressed by the driver, the hydraulic pressure of the master cylinder 9 is equal to or higher than a predetermined pressure (for example, 0.4 MPa), and the vehicle speed of the vehicle 1 is a predetermined stop vehicle speed (for example, 7 km). / H) The condition is as follows. When the stop condition is satisfied, an engine stop request is output from the idle stop ECU 24 to the engine ECU 21, and the engine 2 is automatically stopped by the engine ECU 21.

  While the engine 2 is automatically stopped by the idle stop control, it is repeatedly determined whether or not a predetermined restart condition is satisfied. The restart condition is, for example, a condition that the foot is released from the brake pedal 8 during the automatic stop of the engine 2. Whether the foot is released from the brake pedal 8 is determined based on, for example, a state of a brake switch (not shown) that is turned on when the brake pedal 8 is depressed. When the restart condition is satisfied, the relay 13 is turned on by the idle stop ECU 24. When the relay 13 is turned on, the engine 2 is started through cranking by the starter 5.

<Wheel cylinder pressure control>

  FIG. 2 is a timing chart for explaining the wheel cylinder pressure control.

  When the stop condition in the idle stop control is satisfied, an engine stop request signal is transmitted from the idle stop ECU 24 to the engine ECU 21 in response to this (time T1). The engine ECU 21 receives the engine stop request signal and automatically stops the engine 2.

  In response to the establishment of the stop condition in the idle stop control, a braking force reduction request signal is transmitted from the idle stop ECU 24 to the brake ECU 23. The brake ECU 23 receives the braking force reduction request signal and sets a reduction range corresponding to the acceleration (deceleration) in the deceleration direction of the vehicle 1 detected by the G sensor 26. Then, the brake ECU 23 controls the brake actuator 11 so that the wheel cylinder pressure detected by each wheel cylinder pressure sensor 29 is reduced by the set reduction width (time T1).

  Thereafter, the rotational speed of the engine 2 decreases to 0 rpm (time T2), and the engine 2 enters an idle stop state.

  When the vehicle speed of the vehicle 1 decreases to a predetermined holding vehicle speed (for example, 1 km / h), the brake ECU 23 holds the wheel cylinder pressure of each brake 7 (the wheel cylinder pressure detected by each wheel cylinder pressure sensor 29) for a predetermined hold. Holding control, which is control of the brake actuator 11 for holding the pressure or higher, is started (time T3).

  In the holding control, first, the wheel cylinder pressure is held at the pressure when the engine 2 is in the idle stop state. Thereafter, when the vehicle speed of the vehicle 1 becomes 0 km / h, the wheel cylinder pressure is held at the hold pressure.

  When the driver's foot is released from the brake pedal 8, the restart condition of the idle stop control is established, and the starter 5 is cranked for restarting the engine 2 (time T5).

  The holding control is continued by the brake ECU 23 until the engine 2 restarts (complete explosion) after the cranking starts (time T5-T6). Thus, even when the driver's foot is released from the brake pedal 8 while the vehicle 1 is stopped on the slope, the vehicle 1 can be prevented from sliding down the slope.

  When the engine 2 is restarted (time T6), the brake ECU 23 ends the holding control and controls the brake actuator 11 (pressure reduction control) so that the wheel cylinder pressure of each brake 7 gradually decreases. As a result, the braking force from the brake 7 to the wheels gradually decreases, and the vehicle 1 starts to accelerate slowly.

  FIG. 3 is a graph showing the relationship between deceleration and wheel cylinder pressure.

  When the brake pedal 8 is depressed while the vehicle 1 is traveling, the higher the wheel cylinder pressure of each brake 7 is, the greater the braking force applied to the wheel from each brake 7 is, so the deceleration of the vehicle 1 is greater. In other words, the greater the deceleration of the vehicle 1, the stronger the brake pedal 8 is depressed, and the greater the braking force applied to the wheels from each brake 7.

  When the braking force reduction request signal is transmitted from the idle stop ECU 24 to the brake ECU 23, the reduction range of the wheel cylinder pressure is set to a larger value as the deceleration of the vehicle 1 detected by the G sensor 26 is larger.

<Effect>

  As described above, when the brake 7 of the vehicle 1 is actuated while the engine 2 of the vehicle 1 is being driven and a predetermined stop condition is satisfied, the engine 2 is automatically stopped. The stop condition includes a condition that the vehicle speed has decreased to a stop vehicle speed greater than 0 km / h. When the engine 2 is automatically stopped, the braking force (wheel cylinder pressure) by the brake 7 is reduced.

  When the braking force by the brake 7 is constant, the deceleration of the vehicle 1 increases with the automatic stop of the engine 2. When the engine 2 is automatically stopped, the braking force by the brake 7 is reduced, so that a change in deceleration accompanying the automatic stop of the engine 2 can be suppressed. As a result, it is possible to prevent the driver from feeling slowed down.

  Further, as the deceleration of the vehicle 1 is detected and the detected deceleration is larger, the braking force by the brake 7 is reduced with a larger reduction width. Thereby, the change of the deceleration accompanying the automatic stop of the engine 2 can be suppressed satisfactorily while ensuring the necessary and sufficient deceleration for stopping the vehicle 1. As a result, the vehicle 1 can be stopped satisfactorily while further preventing the driver from feeling of deceleration.

<Modification>

  As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  The vehicle 1 is not limited to an automobile that uses the engine 2 as a drive source, but may be a hybrid car that uses an engine and a motor as drive sources, or an electric car that uses a motor as a drive source.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

1 vehicle 2 engine (drive source)
7 Brake 23 Brake ECU (reducing means)
24 Idle stop ECU (Idle stop means)
26 G sensor (detection means)

Claims (1)

In response to the establishment of a predetermined stop condition including the condition that the vehicle brake is activated and the vehicle speed is reduced to a predetermined vehicle speed greater than 0 km / h during driving of the vehicle drive source, the drive Idle stop means for automatically stopping the source,
When the stop condition is satisfied and the drive source is automatically stopped by the idle stop means, a reduction means for reducing the braking force by the brake ;
I saw including a detection means for detecting deceleration of the vehicle,
The control device for a vehicle , wherein the reduction means reduces the braking force by the brake with a reduction width corresponding to the deceleration detected by the detection means .

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