JP5817386B2 - Engine restart control device - Google Patents

Description

  The present invention stops the engine of the vehicle when a predetermined stop condition is satisfied, restarts the engine when a predetermined restart condition is satisfied after the stop, and brakes when the engine is restarted. The present invention relates to an engine restart control device that maintains brake pressure until engine restart is completed even after pedal operation is released.

In the technique of Patent Document 1, the control unit includes an abnormality detection unit capable of detecting an abnormality of the brake hydraulic pressure holding device, and after determining that the brake hydraulic pressure holding device is abnormal by the abnormality detection unit, the automatic stop condition Among these, the determination condition for the automatic stop execution and the automatic stop prohibition is changed by changing the determination value relating to the actual inclination angle of the vehicle detected by the inclination angle detection means.
In the technique of Patent Document 2, it is determined whether or not an engine start condition is satisfied after the engine is automatically stopped. If the engine start condition is satisfied, a start command is sent to the engine to start the engine, and the turbine speed is set to 600 rpm. The hill hold control unit holds the brake fluid pressure until it exceeds 300 rpm. When the turbine speed falls below 300 rpm, the brake fluid pressure is reduced.

JP 2008-128132 A JP 2010-52568 A

The idle stop system is a system that automatically stops the engine without operating the ignition key when the vehicle stops due to traffic light or traffic congestion, and then automatically restarts the engine.
In addition, when the engine is stopped by an idle stop system on a slope such as an uphill road, the hill hold control is performed after the driver releases the brake pedal when the engine is restarted. This is a control that keeps the brake pressure and prevents the vehicle from sliding down until it is stepped on. In this hill hold control, the brake pressure is gradually reduced to 0 after the engine is restarted.

  However, when the brake pressure is reduced after the engine is restarted, if the brake pressure is reduced at a constant reduction speed as disclosed in Patent Documents 1 and 2, the holding pressure is increased all at once when the reduction speed is too high. Since the pressure is reduced, there is a problem that a downhill road or the like gives an uncomfortable feeling such as a feeling that the vehicle suddenly jumps out when the vehicle starts. In addition, when the decompression speed is too slow, there is a problem that an uncomfortable feeling such as a drag feeling that drags a brake when the vehicle starts is given.

  The object of the present invention is to provide a vehicle jumping feeling and brake dragging feeling when the brake pressure is maintained until the engine restart is completed even after the brake pedal operation is released at the time of restarting the vehicle engine. It is to prevent it.

  (1) One embodiment of the present invention is an engine that stops a vehicle engine when a predetermined stop condition is satisfied, and restarts the engine when a predetermined restart condition is satisfied after the stop. In an engine restart control device comprising: a control means; and a brake pressure holding means for holding a brake pressure until the restart of the engine is completed even after an operation of a brake pedal is released upon restart of the engine An engine restart control device comprising pressure reducing means for gradually reducing the brake pressure after the completion of engine restart and changing the pressure reduction speed during pressure reduction when the brake pressure is reduced; is there.

(2) In the embodiment of (1), the pressure reducing means reduces the brake pressure at a first pressure reduction speed when the brake pressure is greater than a predetermined pressure when the brake pressure is reduced, and is equal to or lower than the predetermined pressure. In this case, the brake pressure may be reduced at a second pressure reduction speed smaller than the first pressure reduction speed.
(3) In the embodiment of (2), the vehicle further includes vehicle speed detection means for detecting the vehicle speed of the vehicle and inclination angle detection means for detecting the inclination angle of the vehicle, wherein the pressure reduction means is detected by the vehicle speed detection means. The predetermined pressure may be obtained based on the inclination angle detected by the inclination angle detecting means when the vehicle speed is zero.

(4) In the embodiment of (3), further comprising accelerator opening detecting means for detecting an accelerator opening, wherein the decompressing means detects an accelerator operation by the accelerator opening detecting means while reducing the brake pressure. When the vehicle speed is detected by the vehicle speed detection means in a state where it is not, the predetermined pressure may be obtained based on the detected vehicle speed.
(5) In the embodiment of (2), further comprising accelerator opening detecting means for detecting an accelerator opening, wherein the decompressing means detects an accelerator operation by the accelerator opening detecting means while reducing the brake pressure. In this case, the brake pressure may be reduced at a third pressure reduction speed greater than the first pressure reduction speed.

(6) In the embodiment of (5), the pressure reducing means may determine the third pressure reduction speed based on the accelerator opening detected by the accelerator opening detecting means. Good.
(7) In the embodiment of (2), further comprising an inclination angle detecting means for detecting an inclination angle of the vehicle, wherein the pressure reducing means is based on the inclination angle detected by the inclination angle detecting means. The speed may be obtained.

According to the embodiment of (1), when the brake pressure is reduced, the pressure reduction speed is changed in the middle of the pressure reduction, thereby preventing the vehicle from popping out due to the brake pressure reduction speed being too high and the vehicle holding force suddenly disappearing. In addition, it is possible to prevent a feeling of dragging due to a delay in reducing the brake pressure due to the brake pressure reducing speed being too small.
According to the embodiment of (2), when the brake pressure is higher than the predetermined pressure, the brake pressure is reduced at the first pressure reduction speed to prevent a drag feeling, and when the brake pressure is lower than the predetermined pressure, the brake is applied at the second pressure reduction speed. A feeling of popping out can be prevented by reducing the pressure.

According to the embodiment of (3), since the predetermined value is changed according to the inclination angle of the vehicle, when the brake pressure is reduced, the vehicle holding force on the uphill road suddenly disappears. It is possible to prevent the vehicle from popping out due to the vehicle holding force suddenly disappearing on the downhill road.
According to the embodiment of (4), when the vehicle starts to move due to its own weight, the predetermined pressure is obtained based on the vehicle speed when the vehicle starts to move. It is possible to prevent the vehicle from slipping down due to sudden loss of the holding force and from jumping out of the vehicle due to sudden loss of vehicle holding force on the downhill road.

According to the embodiment of (5), when the accelerator is operated, it is considered that the driver is willing to start the vehicle. In this case, the brake pressure reduction speed is increased to delay the brake pressure reduction. It is possible to prevent the feeling of dragging by.
According to the embodiment of (6), since the brake pressure reduction speed is obtained based on the accelerator opening, the brake pressure reduction speed is also increased when the accelerator opening is large, thereby preventing a feeling of dragging due to a delay in brake pressure reduction. can do.

  According to the embodiment of (7), since the pressure reduction speed of the brake pressure is obtained based on the inclination angle, when the brake pressure reduction speed is large, the vehicle slides down due to the vehicle holding force suddenly disappearing on the uphill road Further, it is possible to prevent the vehicle from jumping out due to the vehicle holding force suddenly disappearing on the downhill road.

It is a block diagram which shows the control system of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a flowchart of the brake holding | maintenance control of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a flowchart explaining the engine complete explosion process of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a flowchart explaining the pressure reduction process of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a flowchart explaining the process during engine starting of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a flowchart explaining the process during idling stop of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a timing chart explaining the hill hold control of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a timing chart explaining the hill hold control of the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring target holding pressure based on the inclination-angle of a vehicle with the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring a predetermined pressure based on a vehicle speed with the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring a predetermined pressure based on an inclination angle with the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring a pressure reduction value based on a target holding pressure with the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring a pressure reduction value based on the inclination-angle of a vehicle with the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring a pressure reduction value based on the holding pressure of a brake pressure with the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring a pressure reduction value based on the inclination-angle of a vehicle with the engine restart control apparatus of the vehicle which is one embodiment of this invention. It is a graph explaining the table for calculating | requiring a pressure reduction value based on an accelerator opening with the engine restart control apparatus of the vehicle which is one embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described.
FIG. 1 is a block diagram showing a control system of an engine restart control device for a vehicle 1 according to an embodiment of the present invention. The vehicle 1 according to the present embodiment includes an idle stop system. The idle stop system is a system that automatically stops the engine 2 without the driver operating the ignition key when the vehicle 1 stops due to a signal waiting or traffic congestion, and then automatically restarts the engine 2. . Execution of the automatic stop of the engine 2 is performed when a predetermined automatic stop condition is satisfied, for example, when the brake pedal 4 is depressed and the speed of the vehicle 1 becomes zero. The restart of the engine 2 is performed when a predetermined restart condition is satisfied, for example, the brake pedal 4 is released and an accelerator pedal (not shown) is depressed. These idle stop systems are controlled by an engine controller 3 that controls the engine 2, thereby realizing an engine control means.

  The control device 9 is a device that controls the brake system of the vehicle 1 and is configured around a microcomputer. In the brake system, the depression force of the brake pedal 4 is transmitted to the master cylinder 6 via the booster 5. A brake pressure holding device 7 is connected to the master cylinder 6. The master cylinder 6 is a hydraulic cylinder that transmits the depression force of the brake pedal 4 to the brake pressure holding device 7. The brake pressure holding device 7 is provided with a predetermined hydraulic circuit, and generates a brake pressure for braking the front and rear wheels 8. The brake pressure holding device 7 is connected to the control device 9 and is controlled by the control device 9.

  The control device 9 includes a brake switch 11 that detects whether or not the brake pedal 4 is depressed, an accelerator opening sensor 12 that serves as an accelerator opening detecting means that detects the accelerator opening, and the inclination angle of the vehicle 1. An inclination angle sensor 13 serving as an inclination angle detecting means for detecting, a master cylinder pressure sensor 14 detecting an oil pressure (master cylinder pressure) of the master cylinder 6, an engine controller 3, and a vehicle speed sensor serving as a vehicle speed detecting means for detecting a vehicle speed. 15 is connected. The control device 9 can acquire necessary information regarding the engine 2 such as the rotational speed of the engine 2 from the engine controller 3.

  In the above-described idle stop system, the control device 9 performs hill hold control. In the hill hold control, when the engine 2 is stopped by an idle stop system on a slope such as an uphill road, the accelerator pedal is released after the driver releases the brake pedal 4 when the engine 2 is restarted thereafter. The brake pressure is maintained until the vehicle 1 is changed over to prevent the vehicle 1 from sliding down. That is, when it is determined by the tilt angle sensor 13 that the place where the engine 2 is stopped is tilted, the brake pressure holding device 7 is controlled to hold the brake pressure so that the vehicle 1 does not slip even on the slope. That is, the brake pressure holding device 7 functions as a brake pressure holding means for holding the brake pressure until the restart of the engine 2 is completed even after the operation of the brake pedal 4 is released when the engine 2 is restarted during idling stop. Have More specifically, when the master cylinder pressure sensor 14 detects that the master cylinder pressure is equal to or lower than a predetermined pressure, the brake pressure holding device 7 starts holding the brake pressure. When the engine 2 is restarted, the brake pressure is gradually reduced and the brake is released.

Below, the holding | maintenance of the brake pressure by hill hold control is demonstrated in detail.
FIG. 2 is a flowchart of the brake holding control. Such processing is started by turning on the ignition key. First, it is determined whether or not the engine 2 is in a complete explosion (step S1). Whether or not the engine 2 is in a complete explosion is determined by whether or not an engine complete explosion flag, which will be described later, is set. When the engine 2 is in a complete explosion (Y in step S1), an engine complete explosion process (details will be described later) is performed (step S2).

When the engine 2 is not completely exploded (N in Step S1), it is determined whether or not the engine 2 is being started (Step S3). Whether or not the engine 2 is being started is determined based on whether or not an engine starting flag to be described later is set. When the engine 2 is starting (Y in step S3), an engine starting process (details will be described later) is performed (step S4).
When the engine 2 is not being started (N in step S3), it is determined whether or not the engine 2 is idling stop by the above-described idling stop system (step S5). Whether or not an idle stop is in progress is determined by whether or not an idle stop flag to be described later is set. When the engine is idling stop (Y in step S5), processing during idling stop (details will be described later) is performed (step S6).

  If the engine complete explosion process (step S2), engine start process (step S4), idle stop process (step S6) is completed, or if the engine is not idling stop as determined in step S5, the ignition key As long as is not turned off (N in step S7), the process returns to step S1. When the ignition key is turned off (Y in step S7), the series of processes is terminated.

  FIG. 3 is a flowchart for explaining the engine complete explosion process (step S2). First, it is determined whether or not the current holding pressure is zero for the brake pressure (step S11). When the holding pressure is not 0 (N in Step S11), a pressure reduction process (described later) is performed (Step S12). That is, when the engine 2 is completely exhausted and started, if the brake pressure is not yet zero and the brake is applied by the hill hold control, the decompression process is performed.

  Next, it is determined whether or not an automatic stop condition is satisfied in the idle stop system (step S13). Examples of the automatic stop condition include that the brake pedal 4 is depressed and the speed of the vehicle 1 becomes zero. When the automatic stop condition is satisfied (Y in step S13), an idle stop flag indicating that the idle stop is being performed is set (step S14). When the automatic stop condition is satisfied, the engine controller 3 performs an idle stop of the engine 2.

FIG. 4 is a flowchart for explaining the decompression process (step S12). In this process, first, it is determined whether or not the driver has an intention to start the vehicle 1 (step S21). Whether or not the driver intends to start the vehicle 1 can be determined by determining whether or not the accelerator pedal is depressed by the accelerator opening sensor 12.
When the driver intends to start the vehicle 1 (Y in Step S21), a predetermined reduced pressure value (reduced pressure value 3) is subtracted from the current holding pressure of the brake pressure, and the value after the subtraction is newly set. Is set as a proper holding pressure (holding pressure = holding pressure−reduced pressure value 3) (step S22).

  When the driver does not intend to start the vehicle 1 (N in Step S21), it is determined whether or not the vehicle speed can be detected by the vehicle speed sensor 15 (Step S23). When the vehicle speed is detected (Y in step S23), a “predetermined pressure” (a predetermined pressure M2 described later) is obtained based on the vehicle speed (step S24). This predetermined pressure is a value serving as a threshold for the current holding pressure of the brake pressure (described later). When the vehicle speed is not detected (N in step S23), a “predetermined pressure” is obtained based on the inclination angle of the vehicle 1 detected by the inclination angle sensor 13 (step S25).

Next, the current holding pressure of the brake pressure is compared with the predetermined pressure obtained in step S24 or S25 (step S26). If “holding pressure ≦ predetermined pressure” (Y in step S26), the brake pressure Then, a predetermined reduced pressure value (reduced pressure value 2) is subtracted from the current holding pressure, and the value after the subtraction is set as a new holding pressure (holding pressure = holding pressure−reduced pressure value 2) (step S27).
When “holding pressure> predetermined pressure” (N in step S26), a predetermined reduced pressure value (reduced pressure value 1) is subtracted from the current holding pressure of the brake pressure, and a new value after subtraction is newly obtained. The holding pressure is set (holding pressure = holding pressure−reduced pressure value 1) (step S28).

Here, “pressure reduction value 3> pressure reduction value 1> pressure reduction value 2”. Therefore, among steps S22, S27, and S28, the step of using the pressure reduction value 3 has the greatest decrease in the brake holding pressure. In S22, the smallest way to decrease the brake holding pressure is in step S27 using the reduced pressure value 2. That is, by repeating the process of FIG. 4, decompression speed of the brake holding pressure (degree edge configurations for holding pressure per unit time), step S22, step S28, is smaller in the order of step S27.

  FIG. 5 is a flowchart for explaining the engine starting process (step S4). First, it is determined whether or not a start completion condition for the engine 2 is satisfied (step S31). Whether or not the engine start completion condition is satisfied is determined based on the engine speed. For example, a predetermined value 1 and a predetermined value 2 are prepared as threshold values for the rotational speed of the engine 2, and when “0 <predetermined value 2 <predetermined value 1”, the rotational speed of the engine 2 is equal to or greater than the predetermined value 1. Alternatively, it is determined that the engine start completion condition is satisfied after the engine speed is equal to or greater than the predetermined value 2 and a predetermined determination time has elapsed.

When the engine start completion condition is satisfied (Y in step S31), an engine complete explosion flag indicating that the engine has started during complete explosion is set (step S32). When the engine start completion condition is not satisfied (N in Step S31), the holding hydraulic pressure of the brake pressure is set to a target hydraulic pressure (a target hydraulic pressure M1 described later) (Step S33).
FIG. 6 is a flowchart for explaining the idling stop process (step S6). First, it is determined from the pressure of the master cylinder 6 or the like, for example, whether or not a predetermined engine start start condition is satisfied (step S41). When it is determined that the engine 2 start start condition is satisfied and the engine 2 has started (Y in step S41), an engine start flag indicating that the engine 2 is being started is set. (Step S42). When it is determined that the engine 2 start start condition is not satisfied and the engine 2 has not started (N in Step S41), the target hydraulic pressure of the brake pressure is maintained (Step S33). The target hydraulic pressure M1) set in step S43 is calculated (step S43).

7 and 8 are timing charts for explaining hill hold control. 7 and 8, “starter drive” indicates ON / OFF of a starter that starts the engine 2. 7 and 8, a part of the brake holding pressure is displayed in an enlarged manner.
In FIG. 7, first, an automatic stop condition (step S13) of the engine 2 is established at time t1, and an idle stop is started. Thereafter, a predetermined restart condition of the engine 2 is established, and the restart of the engine 2 is started at time t2. That is, the starter for starting the engine 2 is switched from OFF to ON. At the start of restart of the engine 2, the driver tries to switch from the brake pedal 4 to the accelerator pedal, so that the master cylinder pressure of the master cylinder 6 becomes zero. However, the brake holding pressure is maintained at the aforementioned target holding pressure M1 by the hill hold control.

  Thereafter, the engine 2 is completely exploded at time t3, and the engine 2 is completely started (step S32). In this case, the starter for starting the engine 2 is turned off. Since the brake holding pressure at that time is larger than the predetermined pressure M2, the brake holding pressure is reduced using the reduced pressure value 1 in step S28. Thereafter, at time t4, since the brake holding pressure has decreased to the predetermined pressure M2, the brake holding pressure is reduced using the reduced pressure value 2 in step S27. Therefore, the brake holding pressure reduction speed becomes slower after time t4 as compared to times t3 to t4. At time t5, the brake holding pressure becomes 0, and the hill hold control ends.

  FIG. 8 differs from FIG. 7 in that the state when the accelerator pedal is depressed while the brake holding pressure is being reduced is shown. That is, in FIG. 8, first, at time t6, the automatic stop condition (step S13) of the engine 2 is established and the idle stop is started. Thereafter, a predetermined restart condition for the engine 2 is established, and the restart of the engine 2 is started at time t7. That is, the starter for starting the engine 2 is switched from OFF to ON. Further, at the start of restart of the engine 2, the driver tries to switch from the brake pedal 4 to the accelerator pedal, so that the master cylinder pressure of the master cylinder 6 becomes zero. However, the brake holding pressure is maintained at the aforementioned target holding pressure M1 by the hill hold control.

  Thereafter, the engine 2 is completely exploded at time t8, and the engine 2 is completely started (step S32). In this case, the starter for starting the engine 2 is turned off. Since the brake holding pressure at that time is larger than the predetermined pressure M2, the brake holding pressure is reduced using the reduced pressure value 1 in step S28. Thereafter, at time t9, the accelerator pedal is depressed. As a result, it is determined whether or not the driver intends to start the vehicle 1 (Y in step S21), and the brake holding pressure is reduced using the reduced pressure value 3 in step S22. Therefore, the pressure reduction rate of the brake holding pressure is abrupt after time t9 as compared to times t8 to t9. Thereafter, the brake holding pressure becomes 0, and the hill hold control ends.

  As described above, in the hill hold control of the present embodiment, the brake pressure is gradually reduced after the restart of the engine 2 is completed, but the pressure is reduced by changing the pressure reduction speed during the reduction of the brake pressure. Realize the means. It should be noted that the above-described reduced pressure value 1, reduced pressure value 2, and target holding pressure M1 are obtained during idle stop. Further, the reduced pressure value 1, the reduced pressure value 2, the reduced pressure value 3, the target holding pressure M1, and the predetermined pressure M2 are obtained by table lookup.

  According to the vehicle 1 of the present embodiment, as shown in FIG. 7, when the brake pressure is greater than a predetermined pressure M2, the brake pressure is reduced in a short time by using a reduced pressure value 1 and relatively increasing the pressure reduction speed. Thus, the feeling of dragging of the vehicle 1 can be prevented, and when the brake pressure subsequently becomes equal to or less than the predetermined pressure M2, the feeling of popping out of the vehicle can be prevented by using a reduced pressure value 2 to relatively reduce the pressure reducing speed.

FIG. 9 is a graph for explaining a table for obtaining the target holding pressure M1 based on the inclination angle of the vehicle 1. In the example of FIG. 9, the target holding pressure M1 obtained during the idle stop is determined so as to increase as the inclination angle of the vehicle 1 increases.
FIG. 10 is a graph illustrating a table for obtaining the predetermined pressure M2 based on the vehicle speed. FIG. 11 is a graph for explaining a table for obtaining the predetermined pressure M2 based on the inclination angle. That is, as described above, when the vehicle speed can be detected (Y in Step 23), the predetermined pressure M2 is obtained based on the vehicle speed (Step 24), and when the vehicle speed cannot be detected (N in Step 23), the inclination A predetermined pressure M2 is obtained based on the angle (step 25).

In FIG. 11, since the predetermined value M2 increases as the inclination angle of the vehicle 1 increases (step 25), the vehicle holding force suddenly disappears on the uphill road when the brake pressure reduction speed is large. It is possible to prevent the vehicle 1 from jumping out due to the vehicle holding force suddenly disappearing on a downhill or downhill road.
In FIG. 10, when the vehicle 1 starts to move due to its own weight, the predetermined pressure M2 increases as the vehicle speed when the vehicle 1 starts moving (step 24). When the vehicle is large, it is possible to prevent the vehicle 1 from slipping down due to a sudden loss of vehicle holding force on an uphill road or from jumping out of the vehicle 1 due to a sudden loss of vehicle holding force on a downhill road.

  FIG. 12 is a graph for explaining a table for obtaining the reduced pressure value 1 based on the target holding pressure M1. FIG. 13 is a graph for explaining a table for obtaining the reduced pressure value 1 based on the inclination angle of the vehicle 1. As described above, the reduced pressure value 1 is obtained by table lookup during idle stop. However, in the table used in this case, the reduced pressure value 1 may be obtained based on the target holding pressure M1 as shown in FIG. The pressure reduction value 1 may be obtained based on the inclination angle of the vehicle 1 as shown in FIG. In any case, as the target holding pressure M1 and the inclination angle increase, the pressure reduction value 1 also increases and the brake pressure reduction speed increases.

  FIG. 14 is a graph for explaining a table for obtaining the reduced pressure value 2 based on the holding pressure of the brake pressure. FIG. 15 is a graph for explaining a table for obtaining the reduced pressure value 2 based on the inclination angle of the vehicle 1. As described above, the pressure reduction value 2 is obtained by table lookup during idling stop. In the table used in this case, the brake pressure holding pressure is less than the predetermined value M2 based on the inclination angle of the vehicle 1 as shown in FIG. The pressure reduction value 2 at the time is obtained.

In the example of FIG. 14, when the holding pressure of the brake pressure is equal to or lower than the predetermined pressure M2, the pressure reduction value 2 is constant.
In the example of FIG. 15, the value of the pressure reduction value 2 decreases as the inclination angle of the vehicle 1 increases. Therefore, the brake pressure reduction speed becomes slower as the inclination angle increases. In this case, the value of the depressurization value 2 and, in turn, the depressurization speed is decreased in accordance with the increase in the tilt angle of the vehicle 1, and the vehicle 1 slides down or descends due to the vehicle holding force suddenly disappearing on the uphill road Thus, it is possible to prevent the vehicle 1 from jumping out due to the vehicle holding force suddenly disappearing.

FIG. 16 is a graph illustrating a table for obtaining the reduced pressure value 3 based on the accelerator opening. As described above, the depressurization value 3 is obtained by table lookup during idle stop. In the example of FIG. 16, the depressurization value 3 increases as the accelerator opening increases, and thus the depressurization speed increases.
In this case, as shown in FIG. 8, the brake pressure reduction speed at the pressure reduction value 3 is larger than the brake pressure reduction speed at the pressure reduction value 1. That is, when the accelerator is operated, it is considered that the driver intends to start the vehicle (Y in step S21). In that case, the brake pressure reduction speed is increased (step S22), and the brake pressure is reduced. A feeling of dragging due to a delay in decompression can be prevented.

  Further, since the brake pressure reduction speed is determined based on the accelerator opening, the brake pressure reduction speed can be increased when the accelerator opening is large, thereby preventing the feeling of dragging due to a delay in brake pressure reduction.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Engine 3 Engine controller 6 Master cylinder 7 Brake pressure holding device 11 Brake switch 12 Accelerator opening sensor 13 Inclination angle sensor 14 Master cylinder pressure sensor 15 Vehicle speed sensor

Claims (5)

Engine control means for stopping the engine of the vehicle when a predetermined stop condition is satisfied, and restarting the engine when a predetermined restart condition is satisfied after the stop;
Brake pressure holding means for holding the brake pressure until the restart of the engine is completed even after the operation of the brake pedal is released upon restart of the engine;
In the engine restart control device comprising:
Accelerator opening detection means for detecting the accelerator opening,
After the restart of the engine is completed, the brake pressure is gradually reduced, and when the brake pressure is reduced, if the brake pressure is higher than a predetermined pressure, the brake pressure is reduced at a first pressure reduction speed to be equal to or lower than the predetermined pressure. In this case, the brake pressure is reduced at a second pressure reduction speed smaller than the first pressure reduction speed, and when an accelerator operation is detected by the accelerator opening detection means, a third pressure higher than the first pressure reduction speed is detected. An engine restart control device comprising pressure reducing means for reducing the brake pressure at a reduced pressure speed . Vehicle speed detecting means for detecting the vehicle speed of the vehicle;
An inclination angle detecting means for detecting an inclination angle of the vehicle;
Further comprising
The pressure reducing means obtains the predetermined pressure based on an inclination angle detected by the inclination angle detecting means when the vehicle speed detected by the vehicle speed detecting means is zero;
The engine restart control device according to claim 1. Before SL decompression means, the said brake pressure based on the detected vehicle speed when the vehicle speed detected by the vehicle speed detecting means in a state in which the accelerator operation is not detected by the accelerator opening detection means vacuo Find the predetermined pressure,
The engine restart control device according to claim 2. Before SL decompression means, on the basis of the accelerator opening detected by the accelerator opening detecting means obtains said third decompression rate of, that the engine restart control apparatus according to claim 1, characterized in. An inclination angle detecting means for detecting an inclination angle of the vehicle;
The decompression means obtains the second decompression speed based on the inclination angle detected by the inclination angle detection means;
The engine restart control device according to claim 1 .

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