JP6569428B2 - Vehicle control device - Google Patents

Description

  The present disclosure relates to a control device for a vehicle equipped with an idle stop device that automatically stops and automatically starts an engine when the vehicle is temporarily stopped.

In recent years, the number of vehicles equipped with an idle stop device has been increasing, and accordingly, it is required to perform an idle stop with a brake operation with a low pedaling force so that the driver can idle stop without burden.
The idle stop device is required to set the threshold value low because at least the brake fluid pressure by the brake operation has reached a predetermined threshold as an automatic engine stop condition when the engine is automatically stopped. Yes.

In general, when the engine is restarted at an idle stop, the brake force depressed by the brake pedal when the vehicle is stopped is maintained, and the brake force is reduced when the vehicle starts.
However, when the brake pedal depressing force is weak from the idle stop to the restart, the above-mentioned brake holding force is insufficient, and when the engine is restarted, especially in the case of a downhill, a feeling of pushing or popping out occurs. .
Therefore, in addition to the brake control for maintaining the braking force depressed by the conventional brake pedal, the braking force by suppressing the rotation of the axle by the interlock means for applying the fastening force to the plurality of friction fastening elements of the automatic transmission. A technique for suppressing the feeling of extrusion or popping out by combining the above has been proposed. For example, it is shown in Patent Document 1.

  This Patent Document 1 discloses an engine automatic stop start control that automatically stops an engine when the vehicle is stopped and the hydraulic pressure of a wheel brake is equal to or higher than a predetermined threshold, and that automatically starts the engine under a predetermined condition. Means, a brake automatic control means adapted to maintain the hydraulic pressure of the wheel brake when the engine is automatically stopped, and a gear position when the engine is automatically stopped when the engine is automatically started. And an interlock means for interlocking the automatic transmission by adding a fastening torque capacity to a frictional engagement element other than the predetermined frictional engagement element and a predetermined frictional engagement element. Yes.

Further, it is disclosed that when the engine is automatically started on a downhill, a braking force is applied by an interlock means to prevent the engine from jumping forward when the engine is started.
Further, the wheel brake is released after a predetermined time from the completion of the automatic start of the engine, and the braking force by the interlock means is released before the wheel brake is released, so that the vehicle is smoothly started. It is also disclosed.

JP 2010-6326 A

  In Patent Document 1, as described above, the wheel brake is released after a predetermined time from the completion of the automatic start of the engine, and the braking force by the interlock means is released before the wheel brake is released. Thus, it is disclosed that the vehicle is smoothly started. That is, before the brake fluid pressure becomes zero, the interlock of the automatic transmission is first released and terminated. Therefore, it is difficult to obtain a smooth braking release action obtained by the frictional engagement element by the interlock means.

The release of braking in the wheel brake is release from the pressure of the brake shoe against the drum inner peripheral surface in the drum brake, or the tightening release of the brake pad to the disc rotor in the disc brake. On the other hand, since the frictional engagement element by the interlock means has a multi-plate clutch structure, the release of braking is more at the last moment of release than the release of the brake shoe or break pad by the drum brake or disc brake. It becomes possible to release smoothly.
Therefore, at the last moment when the interlock torque is released by gradually decreasing the engagement torque capacity of the friction engagement element comprising the multi-plate clutch constituting the interlock means, a smoother release than when the wheel brake is released can be expected.

  In view of these problems, an object of at least one embodiment of the present invention is to provide a fastening force to an idle stop device that automatically stops and automatically starts an engine and a plurality of frictional engagement elements of an automatic transmission when the vehicle is temporarily stopped. In a vehicle control device including an interlocking means to be applied and a wheel brake, the startability when the engine is automatically started to start the vehicle is improved.

A vehicle control apparatus according to at least one embodiment of the present invention includes an automatic engine stop unit that is executed when a predetermined condition is satisfied, an engine restart unit that is executed when a predetermined condition is satisfied, and an automatic transmission that includes a frictional engagement element. In a vehicle control device comprising a machine and a wheel brake,
A wheel brake control unit that applies a braking force by hydraulic pressure of the wheel brake, an interlock control unit of an automatic transmission that applies a tightening force to the friction engagement element to suppress rotation of the axle, and a road surface gradient detection sensor A road surface gradient determination unit that determines a road surface gradient based on the signal of the above, an interlock release control unit that controls the release of the fastening force of the friction engagement element, and a wheel brake release that controls the release of the hydraulic pressure of the wheel brake A control unit, and when the engine is restarted, the wheel brake control unit applies the hydraulic pressure, the interlock control unit fastens the friction engagement element, and the road surface gradient determination unit determines the road surface. When it is determined that the vehicle is flat or descending, the interlock release control unit and the wheel brake release control unit Release of the hydraulic pressure of the wheel brake and release of the fastening force of the friction engagement element are started, and the release of the fastening force of the friction engagement element is completed after the hydraulic pressure release of the wheel brake is completed. It is characterized by that.

  According to such a configuration, in a flat or downhill situation, even when the brake force is held with the brake pedal being weak, it is necessary to suppress the pushing or jumping out of the vehicle at the time of restart. It becomes possible to compensate for the insufficient braking force by interlocking the automatic transmission.

  In addition, the friction engagement element that interlocks the automatic transmission is formed by a multi-plate clutch. Therefore, the braking force is released more than the brake shoes and break pads released by the drum brake and disc brake. It has a characteristic that it can be released smoothly at the last moment.

Therefore, at the last moment when the interlock torque is released by gradually decreasing the engagement torque capacity of the friction engagement element comprising the multi-plate clutch constituting the interlock, a smoother release can be expected than when the wheel brake is released.

By taking advantage of this characteristic, on a flat or down road, the release of the fastening force of the friction engagement element is completed after the release of the hydraulic pressure of the wheel brake, thereby eliminating the feeling of drag and smoothing. To make a fresh start.
Compared to the configuration in which the braking force by the interlock is released before the wheel brake is released, as shown in the prior art document, and the final release of the braking force is left to the release of the wheel brake. A smoother start is possible by taking advantage of the structural characteristics of the elements.

  In some embodiments, the interlock release control unit and the wheel brake release control unit release the fastening force of the friction engagement element after starting the hydraulic pressure release of the wheel brake after the engine restart. It is characterized by starting.

  According to such a configuration, since the release of the engagement force of the friction engagement element is started after the hydraulic pressure release of the wheel brake is started, the release of the engagement force of the friction engagement element is started after the completion of the hydraulic release of the wheel brake. As described above, the final release of the braking force can be left to the release of the frictional engagement element as described above.

In some embodiments, after the hydraulic pressure release of the wheel brake is started, the fastening force of the friction engagement element is kept constant, and after the constant holding, the release of the fastening force of the friction engagement element is started. It is characterized by doing.
According to such a configuration, after the hydraulic pressure release of the wheel brake is started, by keeping the fastening force of the friction engagement element constant, the braking force by the wheel brake and the total braking force by the friction engagement element can be reduced. Since the reduction amount changes more slowly than the reduction amount of the friction engagement element is added, the change in the reduction amount of the braking force is stabilized, so that the braking force can be released more smoothly.

  In some embodiments, when the road surface gradient determination unit determines that the road surface is up during the engine restart, the interlock release control unit and the wheel brake release control unit may perform the engine restart. Then, the hydraulic pressure release of the wheel brake and the release of the fastening force of the friction engagement element are started, and the release of the wheel brake hydraulic pressure is completed after the release of the fastening force of the friction engagement element is completed. It is characterized by comprising.

  According to such a configuration, when the braking force is maintained with the brake pedal being weak in an uphill situation, the automatic braking gear shifts the shortage of the braking force necessary to suppress the slippage during restart. The braking force can be supplemented by the interlock means of the machine.

  In addition, as described above, the friction engagement element that interlocks the automatic transmission is constituted by a multi-plate clutch, so that the release of braking is more than the release of brake shoes and break pads by drum brakes or disc brakes. Has the characteristic that it can be released smoothly at the last moment of release.

  However, in the uphill situation, if the last of the braking force release is left to the frictional engagement element that performs the interlocking, the vehicle with the so-called hill start assist function will cause the vehicle to slide down by the braking force control of the wheel brake. Therefore, the hill start assist function may not be properly obtained because the vehicle is controlled so that a proper slope start is performed.

  For this reason, there is a problem that such hill start assist control does not operate properly by completing the release of the hydraulic pressure of the wheel brake after the release of the fastening force of the friction engagement element that performs the interlock is completed. Can be prevented.

  Furthermore, in some embodiments, hydraulic pressure release of the wheel brake is started after the release of the fastening force of the friction engagement element is completed.

  With this configuration, the vehicle has an idle stop device for automatically stopping and automatically starting the engine, and a mechanism for operating an interlock by a frictional engagement element of the automatic transmission, and further includes a hill start assist function. Even in a vehicle, it is possible to obtain the slip prevention function by the interlock function by the frictional engagement element of the automatic transmission, and it is possible to reliably prevent the above-mentioned hill start assist function from being obtained, and the hill start assist control. You can get a slope start by.

  According to at least one embodiment of the present invention, when the vehicle is temporarily stopped, an idle stop device that automatically stops and automatically starts the engine, and interlock means that applies a fastening force to a plurality of frictional engagement elements of the automatic transmission. In a vehicle control device equipped with a wheel brake, when the engine is automatically started to start the vehicle, on a flat or downhill, it prevents a feeling of extrusion or popping out and enables a smooth start. Thus, startability can be improved.

  Further, according to at least one embodiment, in addition to the above-described effects, it is possible to improve the startability by preventing a feeling of slipping and enabling a smooth start on an uphill.

1 is a schematic diagram illustrating an overall configuration of a vehicle control device according to an embodiment of the present invention. The time chart of using both wheel brake and interlock on a flat or down road surface is shown. The time chart of the wheel brake and interlock combined use in the up road surface is shown. It is a flowchart which shows control of a control apparatus. It is a flowchart which shows the subroutine in a flat or down road surface. (A) is a flowchart which shows the subroutine in the up road surface. (B) shows another example of step S96 of (A).

  Several embodiments of the present invention will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Only.

  FIG. 1 is a schematic diagram showing the overall configuration of a vehicle control apparatus according to an embodiment of the present invention. As shown in the figure, the vehicle includes an automatic transmission 5 attached to the output shaft 3 of the engine 1. In this example, the automatic transmission 5 includes a torque converter 7 as a fluid transmission device and a plurality of planetary gears. A main transmission unit 9 having a gear mechanism, and an auxiliary transmission unit 15 provided with two friction engagement elements 11 and 13 and capable of switching the output from the main transmission unit 9 in two stages.

  A plurality of shift stages are formed by the main transmission unit 9 having a plurality of planetary gear mechanisms, and the output thereof is further shifted in two stages by the auxiliary transmission unit 15. The first clutch 11 and the second clutch 13, which are two friction engagement elements, are each formed by a multi-plate clutch structure, and the hydraulic pressure generated by a hydraulic pump driven by the engine 1 is supplied to the first clutch. 11 and the second clutch 13 are controlled to supply and discharge, thereby controlling the joining and releasing of the two first clutches 11 and the second clutch 13.

  For example, the first gear 11 is engaged to maintain the first gear, and the second clutch 13 is engaged to hold the second gear. When the vehicle is started, the first gear 11 is engaged to maintain the first speed gear stage. At that time, when the second clutch 13 is engaged, the gear shift that forms the first speed gear stage is performed. The rotation of the output shaft 17 is suppressed by the ratio and the gear ratio of the gear that forms the second gear, and the automatic transmission 5 is interlocked.

  In the present embodiment, a so-called automatic transmission (automatic transmission, AT) including the main transmission unit 9 and the auxiliary transmission unit 15 as the automatic transmission 5 has been described. However, the auxiliary transmission unit 15 is not provided, An automatic transmission having only the main transmission unit 9 and a continuously variable transmission such as a CVT or a toroidal type are also included, and the interlock is executed by joining and releasing of frictional engagement elements provided in these transmissions. The control apparatus of this embodiment can be applied.

  The drive output from the automatic transmission 5 is transmitted to the drive wheel 19 via a power transmission mechanism such as the output shaft 17. A wheel brake 21 is mounted on the drive wheel 19. For example, when the wheel brake 21 is a disc brake, the brake pad 25 for the disc rotor 23 is tightened, held in a tightened state, and released. Be controlled.

A pipe 29 for supplying a wheel cylinder hydraulic pressure (W / C hydraulic pressure) to a wheel cylinder 27 for moving the brake pad 25 is connected between the brake control valve 31.
The brake control valve 31 is connected to the output portion of the master cylinder 35 by a pipe 33. The stepping pressure generated by the depression of the brake pedal 39 is amplified by the booster device of the brake booster 37, and the hydraulic pressure corresponding to the depression is output as the master cylinder hydraulic pressure (M / C hydraulic pressure).
The hydraulic pressure controlled by the brake control valve 31 is supplied to the wheel cylinder 27 in order to move the brake pad 25.

Next, the control device 41 will be described.
The control device 41 mainly includes an engine control ECU (Electronic Control Unit) 43 that controls the operating state of the engine 1, a transmission control ECU 45 that controls the shift control of the automatic transmission 5 and the start and release of the interlock. A brake control ECU 47 that controls the holding and releasing of the braking force by the operation of the brake pedal 39, and a road surface gradient determination unit 51 that determines the gradient of the road surface on which the vehicle is traveling by a signal from the road surface gradient detection sensor 49. doing.

  The engine control ECU 43 includes an engine automatic stop means 53 that is executed on condition that the braking force by the brake pedal 39 is not less than a predetermined value, the vehicle speed is zero, the engine speed is in an idle state, and the like. Engine restart means 55 that is executed on condition that the force is less than a predetermined value, the vehicle speed is zero, the engine speed is in an idle state, and the like.

  As the braking force of the brake pedal 39, the master back hydraulic pressure is detected by the pressure sensor 57, and the detected value is determined by comparing with the braking force determination thresholds Pa and Pb (see FIGS. 2 and 3). . In addition, signals detected by the vehicle speed sensor 59, the engine rotation sensor 61, and the engine load sensor 63 are input to each control ECU of the control device 41 for the vehicle speed, the engine speed, and the engine load, respectively.

  Further, the transmission control ECU 45 controls the shift of the main transmission unit 9 and the sub-transmission unit 15 so as to set an appropriate shift stage according to the engine speed, the engine load, the vehicle speed, and the like. Furthermore, an interlock control unit 65 that executes an interlock that applies a tightening force to the first clutch 11 and the second clutch 13 that are friction engagement elements to suppress the rotation of the axle, and an interlock that controls the release of the interlock. A lock release control unit 67 is provided.

  Further, the brake control ECU 47 is provided with a brake force by the brake fluid pressure generated by the operation of the brake pedal 39, and the brake control valve so as to keep the brake fluid pressure constant during automatic stop (during idle stop). A wheel brake control unit 69 that controls 31 and applies a constant wheel brake force, and a wheel brake release control unit 71 that controls the released hydraulic pressure after releasing the brake pedal 39 are provided.

  The wheel brake control unit 69 and the wheel brake release control unit 71 are controlled by a hill start assist control unit 73 that controls the holding and releasing of the wheel brake force so that the vehicle starts without sliding down when the road surface is in an uphill state. It is designed to operate with the control signal.

  The operation of the control device 41 having the above configuration will be described with reference to the time charts of FIGS. 2 and 3 based on the flowcharts of FIGS.

  In FIG. 4, it is determined in step S1 whether an automatic engine stop condition is satisfied. This determination condition is determined based on whether or not the brake pedal 39 is operated to satisfy a condition that the brake force is equal to or greater than a predetermined value, the vehicle speed is zero, and the engine speed is in an idle state.

  In the time chart of FIG. 2, at time t1 to t2, the vehicle speed is zero and the vehicle is stopped, the braking force of the wheel brake reaches the braking force determination threshold Pa, the engine speed is in an idle state, and is constant in that state. It is determined whether the time (t1 to t2) has elapsed, and it is determined that the automatic stop condition (idle stop) condition is satisfied.

If the automatic stop condition is satisfied in step S1, the brake fluid pressure is held at Pa in step S2, the engine is automatically stopped in step S3, and the engine speed is made zero.
In the time chart of FIG. 2, it is shown that the wheel brake hydraulic pressure (W / C hydraulic pressure) is maintained at Pa and the engine speed is reduced to zero after time t2. Then, idle stop is in progress at times t2 to t3.
The above steps S1 to S3 are performed by the engine automatic stop means 53 of the engine control ECU 43 and the wheel brake control unit 69 of the brake control ECU 47.

Next, in step S4, it is determined whether or not an engine restart condition is satisfied. This determination condition is that the brake force (master cylinder hydraulic pressure (M / C hydraulic pressure)) is lowered to a brake force determination threshold value Pb or less by operating the brake pedal 39, the vehicle speed is zero, the engine speed is in an idle state, and the like. It is determined whether it is established. Note that a difference is provided as a braking force determination threshold Pa> Pb.
An example is shown in which an engine restart condition is satisfied at time t3 in the time chart.

If the engine restart condition is satisfied in step S4, the interlock is executed in step S5, and the engine is restarted in step S6.
In the time chart of FIG. 2, when the restart condition is satisfied at time t3, execution of the interlock is started, and the braking force of the interlock increases from time t3 to t4 as time elapses. The total braking force peak starts at t4, and the total braking force starts decreasing from t4.

  In the present embodiment, the interlock is executed by bringing the second clutch 13 of the sub-transmission unit 15 that forms the second speed into the engaged state. The first clutch 11 that forms the first gear is engaged so that it can start from the automatic stop to the restart of the engine in steps S1 to S6. Therefore, the second clutch 13 is engaged. Then, the rotation of the output shaft 17 is suppressed and locked by the gear ratio of the gear that forms the first gear of the auxiliary transmission unit 15 and the gear ratio of the gear that forms the second gear. As a result, the automatic transmission 5 is interlocked.

At time t3 to t4, the wheel brake is released and the master cylinder hydraulic pressure (M / C hydraulic pressure) is reduced to zero. However, by maintaining the brake hydraulic pressure in step S2, the wheel cylinder hydraulic pressure ( (W / C hydraulic pressure) is maintained at a constant value.
Therefore, during the engine restart from time t3 to t4, the wheel brake control unit 69 applies hydraulic pressure, and the interlock control unit 65 increases the braking force of the interlock, so that the braking force of both the wheel brake and the interlock is increased. Is granted.

  Next, it progresses to step S7 and the gradient of a driving | running | working road surface is determined. The gradient determination is based on a signal from the road surface gradient detection sensor 49 and determines whether the road surface gradient is a flat road, a downward gradient, or an upward gradient as compared with a threshold gradient value. For example, it is determined whether the slope is an upward slope, a flat road, or a downward slope on the basis of an inclination of about 5 °.

  In the case of a flat or descending slope, the process proceeds to step S8, in which the wheel brake is released in the case of a flat or descending slope (release of the brake fluid pressure held in step S2) and the interlock is released (interlock executed in step S5). The lock release subroutine is executed. FIG. 5 shows a subroutine for this flat or downward slope, and FIG. 2 shows a time chart.

  Further, in the case of an ascending slope, the process proceeds to step S9, where the wheel brake is released in the case of the ascending slope (release of the brake fluid pressure held in step S2) and the interlock is released (the interlock executed in step S5). (Release) subroutine is executed. FIG. 6 shows a subroutine in the case of this upward gradient, and FIG. 3 shows a time chart.

(If flat or downhill)
The release of the wheel brake and interlock in the case of flat or downhill will be described.
When the engine is restarted in step S6 in FIG. 4, it is determined in step S81 in FIG. 5 whether the engine speed is equal to or higher than the first threshold value Ra. In step S82, reduction of the brake pressure of the wheel brake is started.
In the time chart of FIG. 2, at time t4, pressure reduction of the wheel cylinder hydraulic pressure (W / C hydraulic pressure) is started. At time t4, the interlock maintains the held state.

  At time t4, when the engine is completely detonated, the interlock braking force is applied. Therefore, when the braking force is held in a flat or downhill state with the brake pedal 39 being weakly depressed. Even so, it is possible to supplement the braking force by the interlock of the automatic transmission 5 for the shortage of the braking force necessary to suppress the pushing or jumping of the vehicle due to the complete explosion of the engine at the restart.

Next, in step S83, it is determined whether the engine speed further increases and the engine speed is greater than or equal to the second threshold value Rb. In step S84, the release of the interlock is started.
In the time chart of FIG. 2, at time t5, the interlock is released from the holding state, and the braking force is reduced due to the interlock.

Next, in step S85, it is determined whether the brake release is completed. That is, the wheel cylinder hydraulic pressure (W / C hydraulic pressure) of the wheel brake is detected by the wheel cylinder hydraulic pressure sensor 64, and it is determined whether or not the hydraulic pressure value has become zero.
In step S86, when it is determined that the release of the brake is completed, the release of the interlock is terminated thereafter.

  That is, after the release of the brake is completed at time t6 in FIG. 2 and the wheel brake is completely released, the release of the interlock is completed at time t7.

As described above, when the interlock is held at a constant braking force from time t4 to time t5 (FIG. 2A), the total braking force of the braking force by the wheel brake and the braking force by the interlock is as shown in FIG. 2B. As shown in FIG. 4, the slope of the change in reduction of the braking force can be made gentle.
Thus, after releasing the hydraulic pressure of the wheel brake, the amount of reduction of the total braking force due to the braking force by the wheel brake and the interlock can be reduced by keeping the fastening force of the frictional engagement element of the interlock constant. Since the change changes more gradually than the reduction amount of the interlock is applied, the change in the reduction amount of the braking force is stabilized, so that the braking force can be released smoothly.

Furthermore, since the release of the interlock braking is terminated after the brake release is completed, the braking force is only released from the interlock at time t6 to t7. It is possible to make the slope of the change of the decrease gentle.
As a result, the final release of the braking force can be entrusted to the release of the frictional engagement element of the interlock, so that the vehicle can smoothly start using the structural characteristics of the frictional engagement element.

That is, since the friction engagement elements of the first clutch 11 and the second clutch 13 that interlock the automatic transmission 5 are formed by a multi-plate clutch structure, the braking force is released by the drum brake or the disc brake. Rather than releasing the brake shoe or break pad by, it has a characteristic that it can be released smoothly at the last moment of release.
For this reason, at the last moment of releasing the interlock by gradually decreasing the engagement torque capacity of the friction engagement element composed of the multi-plate clutch that performs the interlock, a smoother release than when the wheel brake is released can be obtained.

  In addition, when the wheel brake is released and the interlock is released, the change in the total braking force is controlled so as to be a gradual and stable change as shown in A part and B part of FIG. Thus, on a flat or downhill slope, it is possible to prevent a feeling of extrusion or a feeling of popping out, enable a smooth start, and improve startability.

(In the case of ascending slope)
The release of the brake and the interlock in the case of ascending slope will be described.
In the above-described flat or downhill, the final release of the braking force when the engine is restarted is left to the release of the frictional engagement element of the interlock. From the viewpoint of preventing sliding down, it is characterized in that the final release of the braking force at the time of engine restart is left to release by wheel brake by the hill start assist function.

When the engine is restarted in step S6 in FIG. 4, it is determined in step S91 in FIG. 6A whether the engine speed is equal to or higher than the first threshold value Ra. It is determined that the explosion has been completed, and the interlock is held at a constant value in step S92. The brake pressure of the wheel brake has already been held at a constant value in step S2.
In the time chart of FIG. 3, at time t4, the wheel cylinder hydraulic pressure (W / C hydraulic pressure) is in a holding state, and the interlocking also starts to hold the increased braking force.
Accordingly, even when the wheel brake force is held with the brake pedal 39 being weakly depressed, the braking force can be supplemented by the interlock of the automatic transmission 5. The function can surely provide a vehicle sliding prevention function.

Next, in step S93, it is determined whether the engine speed further increases and the engine speed is greater than or equal to the second threshold value Rb. In step S94, the release of the interlock is started.
In the time chart of FIG. 3, at time t5, the interlock holding state (part A in FIG. 3A) is released, and the braking force decreases due to the interlock.

Next, in step S95, it is determined whether the release of the interlock has been completed. That is, the hydraulic pressure that activates the interlock is detected by a hydraulic pressure sensor (not shown), and it is determined whether or not the hydraulic pressure value has become zero.
In the time chart of FIG. 3, the release of the interlock is completed at time t6.

Then, after the interlock is completely released (after the release is completed), in step S96, it is determined whether the engine torque is larger than the gradient load, it is determined whether the slip occurs, and the engine torque is large. In that case, release of the hydraulic pressure of the wheel brake is started in step S97. Thereafter, in step S98, the release of the wheel brake is completed.
In the time chart of FIG. 3, release of the braking force of the wheel brake is started at time t7 and is completed at time t8.

In the above steps S96 to 98, the wheel brake is finally released by the control by the hill start assist control means 73, and the vehicle is prevented from sliding down.
In the uphill situation, if the last of the braking force release is left to the interlocking friction engagement element, the vehicle is equipped with a so-called hill start assist function. The hill start assist function may not be properly obtained because the vehicle is controlled so that the vehicle starts to start a gentle slope, but in this embodiment, such a problem is eliminated, and the vehicle brake is controlled by the wheel brake release control. The fall is surely prevented.

Note that step S96 in FIG. 6A may be modified as step S96 ′ in FIG. 6B. In step S96 ′, it is determined whether a predetermined time has elapsed after the engine speed reaches the first threshold value Ra, and the release of the wheel brake is started after the predetermined time. In this way, by releasing the wheel brake after a predetermined time, quick and reliable braking force release at the time of engine restart is performed, and quick start is possible.
In addition, the release of the interlock is released from time t5 to t6. However, when the accelerator is depressed, this time is set short and released in a short time to release the wheel brake. It may be early.

  As described above, in the case of uphill, the vehicle is equipped with an idle stop device for automatically stopping and automatically starting the engine, and a mechanism for operating an interlock by a frictional engagement element of the automatic transmission. Even if the vehicle has a function, it is possible to prevent the vehicle from slipping by controlling the release of the braking force of the wheel brake by the hill start assist control means 73 as well as preventing the slip by the interlock function by the friction engagement element of the automatic transmission. It is possible to obtain a hill start that has been reliably prevented.

DESCRIPTION OF SYMBOLS 1 Engine 5 Automatic transmission 7 Torque converter 9 Main transmission part 11 1st clutch (friction engagement element)
13 Second clutch (friction engagement element)
15 Sub-transmission unit 21 Wheel brake 31 Brake control valve 39 Brake pedal 41 Control device 43 Engine control ECU
45 Transmission control ECU
47 Brake control ECU
49 Road surface gradient detection sensor 51 Road surface gradient determination unit 53 Engine automatic stop unit 55 Engine restart unit 57 Pressure sensor 59 Vehicle speed sensor 61 Engine rotation sensor 63 Engine load sensor 65 Interlock control unit 67 Interlock release control unit 69 Wheel brake control unit 71 Wheel brake release control unit 73 Hill start assist control means

Claims (5)

In a vehicle control device comprising: an engine automatic stop means that is executed when a predetermined condition is satisfied; an engine restart means that is executed when a predetermined condition is satisfied; an automatic transmission having a friction engagement element; and a wheel brake. ,
A wheel brake control unit for applying a braking force by the hydraulic pressure of the wheel brake;
An interlock control unit of an automatic transmission that applies a tightening force to the friction engagement element to suppress rotation of the axle; and
A road surface gradient determination unit for determining a road surface gradient based on a signal from a road surface gradient detection sensor;
An interlock release controller for controlling release of the fastening force of the friction engagement element;
A wheel brake release control unit for controlling the release of the hydraulic pressure of the wheel brake,
When the engine is restarted, the wheel brake control unit applies the hydraulic pressure, the interlock control unit fastens the friction engagement element, and the road surface gradient determination unit determines that the road surface is flat or down. In this case, the interlock release control unit and the wheel brake release control unit start releasing the hydraulic pressure of the wheel brake and releasing the fastening force of the friction engagement element after restarting the engine. The vehicle control device is configured to complete the release of the fastening force of the friction engagement element after the completion of the hydraulic pressure release.   The interlock release control unit and the wheel brake release control unit start releasing the fastening force of the friction engagement element after starting the hydraulic pressure release of the wheel brake after restarting the engine. The vehicle control device according to claim 1.   The start of releasing hydraulic pressure of the wheel brake, the fastening force of the frictional engagement element is kept constant, and the release of the fastening force of the frictional engagement element is started after the constant holding. Item 3. The vehicle control device according to Item 2.   When the road surface gradient determination unit determines that the road surface is ascending when the engine is restarted, the interlock release control unit and the wheel brake release control unit, after restarting the engine, The pressure release and the release of the fastening force of the friction engagement element are started, and the hydraulic pressure release of the wheel brake is completed after the release of the fastening force of the friction engagement element is completed. The vehicle control device according to claim 1. 5. The vehicle control device according to claim 4, wherein hydraulic release of the wheel brake is started after the release of the fastening force of the friction engagement element is completed.

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