JP5428898B2 - Vehicle control method and vehicle control apparatus - Google Patents

Description

  The present invention relates to a vehicle control method and a vehicle control device that maintain a stop when the vehicle is stopped.

  In general, when a vehicle is stopped by a brake pedal operation by a driver, so-called neutral control is executed for the purpose of improving the fuel consumption of the vehicle. This neutral control is a control for reducing the power transmission efficiency from a drive source (for example, an engine) to wheels by adjusting the input clutch of the automatic transmission to a half-engaged state (or a released state) (Patent Literature). 1). When such neutral control is executed, the creep force based on the creep phenomenon peculiar to the vehicle having the torque converter becomes smaller than when neutral control is not executed. The creep force is a driving force corresponding to the engine speed during idling.

  By the way, when the neutral control is executed when the vehicle traveling on the uphill road is stopped by the driver's operation of the brake pedal, the creep force applied to the wheels is reduced, so that the vehicle may move backward. This is because when the vehicle stops on an uphill road, the creep force acts on the vehicle as a force that suppresses the backward movement of the vehicle. Therefore, in recent years, for example, a stop control device described in Patent Document 2 has been proposed as a device for suppressing the backward movement of the vehicle during the neutral control.

  That is, when the vehicle is stopped and the neutral control is executed, the stop control device described in Patent Document 2 applies to the wheels as the creep force transmitted from the engine side to the wheels decreases as shown in FIG. The brake actuator is operated so that the applied braking force increases (first timing t101). As a result, even when neutral control is executed on a vehicle stopped on an uphill road, the backward movement of the vehicle not intended by the driver is suppressed.

JP 2003-165360 A JP 2006-31378 A

  Incidentally, the brake actuator includes a pump that operates to increase the brake fluid pressure in the wheel cylinder that individually corresponds to the wheel, and a linear electromagnetic valve that is disposed in a flow path that connects the wheel cylinder and the pump. When neutral control is executed while the vehicle is stopped, the pump operates to increase the braking force on the wheel by the amount corresponding to the decrease in the creep force transmitted to the wheel (first timing t101). At this time, the pump (and the motor serving as the drive source of the pump) generates an operation sound accompanying the operation. Such an operation sound can cause discomfort to the vehicle occupant. In addition, there is a time difference from when the neutral control is executed until the pump is operated, the brake fluid pressure in the wheel cylinder increases, and the braking force on the wheels actually increases. Therefore, when the vehicle is stopped on the uphill road and the neutral control is executed, the vehicle may slightly move backward until the braking force on the wheels actually increases.

  Such a problem may occur in an electric vehicle using a motor as a drive source. That is, the electric vehicle operates the motor as a generator and applies a regenerative braking force to the wheels when stopped. Therefore, when a control corresponding to the neutral control is executed when the vehicle is stopped, the regenerative braking force applied to the wheels is reduced. Therefore, the pump of the brake actuator operates to increase the braking force applied to the wheels in order to compensate for the decrease in the regenerative braking force.

  The present invention has been made in view of such circumstances. An object of the present invention is to provide a vehicle control method and a vehicle control device that can suppress generation of an operation sound from the vehicle when the vehicle is stopped.

In order to achieve the above object, a vehicle control method according to the present invention is executed when a braking force corresponding to a brake operation by a vehicle driver is applied to wheels (FR, FL, RR, RL). The vehicle has a plurality of wheels (FR, FL, RR, RL) to which a driving force (Fd) from a driving source (12) of the vehicle is transmitted, and each wheel (FR, FL, RR, RL) and a plurality of wheel cylinders (32a, 32b, 32c, 32d) corresponding to the wheel cylinders (32a, 32b, 32c, 32d) and the brake operation by the driver. In each flow path (33, 34, 36a, 36b, 36c, 36d) connecting the master cylinder (25) that generates fluid pressure (Pmc), the flow of the wheel cylinders (32a, 32b, 32c, 32d). A plurality of adjusting valves (35a, 35b) for adjusting the pressure (Pwc) are provided, and each wheel (FR, FL, RR, RL) is provided in the wheel cylinder (32a, 32b, 32c, 32d). The braking force according to the fluid pressure (Pwc) of the vehicle is applied, and the power is transmitted from the drive source (12) of the vehicle to the wheels (FR, FL, RR, RL) before the vehicle stops. Efficiency reduction step (S32) for operating the input clutch (21) arranged on the route (19, 20) so that the transmission efficiency of the driving force (Fd) to the wheels (FR, FL, RR, RL) is reduced. and) after the stop of the vehicle based on the brake operation, the wheel (FR, FL, RR, and the braking force holding step for holding the braking force applied to RL) (S37), after the braking force holding step (S37) Contact When the vehicle is restarted, the adjustment valves (35a, 35b) are operated so that the braking force reduction modes for the wheels (FR, FL, RR, RL) are different from each other. The wheel speeds (VW) of the wheels (FR, FL, RR, RL) are respectively acquired, and it is determined whether or not there is a regulating valve indicating an abnormality in each of the regulating valves (35a, 35b) based on the obtained result. And an abnormality determination step (S45, S46, S47) .

According to the said structure, before the vehicle stops, the transmission efficiency of the driving force from a drive source to a wheel falls. Therefore, in order to maintain the stop of the vehicle after the vehicle stops, it is only necessary to maintain the braking force applied to the wheels by the brake operation by the driver. That is, in order to automatically increase the braking force on the wheels on the vehicle side, it is not necessary to operate a pump or a motor. Therefore, it is possible to suppress the generation of operating noise from the vehicle when the vehicle is stopped.
Further, when each regulating valve operates normally, the wheel speed of each wheel should show a change corresponding to the mode of reduction of the braking force applied to each wheel. Therefore, in the present invention, an adjustment indicating an abnormality in each adjustment valve is performed based on the wheel speed of each wheel acquired when each pressure regulating valve is operated so that the braking force reduction mode for each wheel is different from each other. It is determined whether there is a valve. Therefore, it is possible to detect whether or not there is a regulating valve indicating abnormality.

  In the vehicle control method of the present invention, the wheels (FR, FL, RR, RL) are provided in the wheel cylinders (32a, 32b, 32c, 32d) individually corresponding to the wheels (FR, FL, RR, RL). A braking force according to the fluid pressure (Pwc) generated in the vehicle is applied, and an inclination angle acquisition step (S60, S66) for acquiring the inclination angle (θ) of the road surface where the vehicle stops is further provided. In the braking force holding step (S37), the road surface inclination angle (θ) obtained by obtaining the fluid pressure of the wheel cylinder (32a, 32b, 32c, 32d) in the inclination angle obtaining step (S60, S66) is large. The gist is to hold it in a high pressure state.

  According to the above configuration, the fluid pressure in the wheel cylinder is maintained at a higher pressure as the inclination angle (or gradient) of the road surface on which the vehicle stops is larger. That is, the braking force applied to the wheels is maintained at a larger value as the road surface inclination angle is larger. Therefore, regardless of the inclination angle of the road surface, the movement of the vehicle unintended by the driver can be suppressed even when the brake operation by the driver is canceled.

  In the vehicle control method of the present invention, in the braking force holding step (S37), if the road surface inclination angle (θ) cannot be acquired in the inclination angle acquisition step (S60, S66), the wheel cylinder (32a, The gist is that the fluid pressure (Pwc) of 32b, 32c, and 32d) is set to a preset fluid pressure (Pwc1).

  According to the above configuration, when the vehicle stops when the road surface inclination angle cannot be acquired, the fluid pressure in the wheel cylinder is adjusted to a preset set value. For this reason, when the set value is set to be equal to or higher than the fluid pressure corresponding to the assumed maximum value of the road surface inclination angle, regardless of the road surface inclination angle, even when the brake operation by the driver is canceled, the driver Unintentional movement of the vehicle can be suppressed.

  The vehicle control method of the present invention further includes a drive source stop step (S38) for stopping the drive source (12) simultaneously with the braking force holding step (S37) or after the braking force holding step (S37). And in the efficiency reduction step (S32), the input clutch (21) is operated so that transmission of the driving force (Fd) to the wheels (FR, FL, RR, RL) is interrupted. The gist.

According to the above configuration, the vehicle stops in a state where transmission of the driving force from the driving source to the wheels is interrupted. And since a drive source is stopped after a vehicle stops, it can contribute to the fuel-consumption improvement of a vehicle.
In the vehicle control method according to the present invention, after the braking force holding step (S37), the input clutch (21) has a transmission efficiency of the driving force (Fd) to the wheels (FR, FL, RR, RL). The gist of the present invention is to further include an efficiency recovery step (S38) that is operated so as to approach the efficiency reduction step (S32) before execution.

  According to the above configuration, when the braking force for the wheel is maintained, the transmission efficiency of the driving force from the driving source to the wheel approaches the state before the execution of the efficiency reduction step. Therefore, when the stopped vehicle is restarted, it can contribute to the quick start of the vehicle.

  The vehicle control method of the present invention includes a deceleration acquisition step (S11, S14) for acquiring a vehicle body deceleration (DVS, G), and a vehicle body speed threshold (DVS, G) as the acquired vehicle body deceleration (DVS, G) increases. A threshold value setting step (S30) for setting KVS) to a large value, and the vehicle body speed (VS) set by the vehicle body speed (VS) in the threshold value setting step (S30). The gist is to execute when the threshold value (KVS) or less is reached.

  According to the above configuration, the vehicle body speed threshold for setting the start timing of the efficiency reduction step is set to a larger value as the vehicle body deceleration increases. Therefore, the transmission efficiency of the driving force from the driving source to the wheels can be reduced before the vehicle stops regardless of the vehicle body deceleration of the vehicle when the vehicle is stopped.

  In the vehicle control method of the present invention, in the current abnormality determination step, the first and second brakes are performed so that the braking force on the first wheel becomes 0 (zero) before the braking force on the second wheel. The first and second regulating valves (35a, 35b) individually corresponding to the wheels (FR, FL, RR, RL) are respectively operated, and in the next abnormality determination step, the braking force on the second wheel is the first. The gist is to operate each of the first and second regulating valves (35a, 35b) to be 0 (zero) before the braking force on one wheel.

  According to the above configuration, in the current abnormality determination step, the wheel speed of the first wheel should be larger than the wheel speed of the second wheel. At this time, when the wheel speed of the second wheel becomes larger than the wheel speed of the first wheel, it can be determined that the adjustment valve corresponding to the second wheel is abnormal. In the next abnormality determination step, the wheel speed of the second wheel should be larger than the wheel speed of the first wheel. At this time, when the wheel speed of the first wheel becomes higher than the wheel speed of the second wheel, it can be determined that the adjustment valve corresponding to the first wheel is abnormal. Therefore, it is possible to specify a regulating valve that shows an abnormality among the regulating valves.

  In the vehicle control method of the present invention, when it is determined in the abnormality determination step (S45, S46, S47) that there is a regulating valve indicating abnormality, the efficiency reduction step (S32) is executed when the vehicle is stopped after the next time. The gist is to regulate this.

  Even if there is a regulating valve indicating an abnormality, if the efficiency reduction step is executed, the braking force against the wheels cannot be properly maintained when the driver cancels the braking operation. There is a risk of movement. In this regard, in the present invention, when there is a regulating valve indicating abnormality, the efficiency reduction step is not executed. Therefore, when the vehicle is stopped in which the efficiency reduction step is executed, the braking force against the wheels is held by the efficiency reduction step, so that the movement of the vehicle unintended by the driver can be suppressed.

On the other hand, the vehicle control device of the present invention is a vehicle control device that maintains a stop of the vehicle when the vehicle is stopped by a brake operation by a driver of the vehicle, and includes a drive source (12). A plurality of wheels (FR, FL, RR, RL) to which the driving force generated by the drive source (12) is transmitted through the power transmission path (19, 20), and the wheels (FR, FL, RR, RL) individually corresponding to a plurality of wheel cylinders (32a, 32b, 32c, 32d), an input clutch (21) provided in the power transmission path (19, 20), and a brake operation by the driver A master cylinder (25) for generating fluid pressure (Pmc), and each flow path (33, 34, 36a, etc.) connecting the wheel cylinders (32a, 32b, 32c, 32d) and the master cylinder (25). 6b, 36c, 36d) and the fluid pressure (Pwc) of the wheel cylinders (32a, 32b, 32c, 32d) provided in the flow paths (33, 34, 36a, 36b, 36c, 36d). A plurality of regulating valves (35a, 35b) and wheel speed detecting means (SE2, SE3, SE4, SE5) for detecting the wheel speed (VW) of each wheel (FR, FL, RR, RL). Each wheel (FR, FL, RR, RL) is applied with a braking force according to the fluid pressure (Pwc) in the wheel cylinder (32a, 32b, 32c, 32d). , the input clutch (21) and said wheel comprising (FR, FL, RR, RL) control means for controlling the braking force applied to the (17,22,25), said control means (17,22,25) includes Serial has a wheel speed obtaining means for obtaining a wheel speed (VW) of the wheels (FR, FL, RR, RL ) , the driving force of the front stop of the vehicle, the wheels (FR, FL, RR, RL ) to A transmission efficiency reduction control for operating the input clutch (21) to reduce the transmission efficiency of (Fd) is performed, and a braking force applied to the wheels (FR, FL, RR, RL) after the vehicle is stopped based on the brake operation. There line braking force holding control to hold, when said after the braking force holding control to resume the running of the vehicle, each wheel (FR, FL, RR, RL ) reduction aspects of braking force are different from each other as for The brake force holding cancel control for operating each of the adjusting valves (35a, 35b) is executed, and the wheel speed (VW) of each wheel (FR, FL, RR, RL) is executed during the brake force hold cancel control. The The gist is to obtain each and determine whether or not there is a regulating valve indicating abnormality in each regulating valve (35a, 35b) based on the obtained result .

  According to the said structure, the effect equivalent to the said vehicle control method can be acquired.

The block diagram which shows typically the vehicle in this embodiment. The block diagram which shows a braking device typically. The map which shows the relationship between the WC pressure in a wheel cylinder, and the electric current value supplied to the electromagnetic coil of a linear solenoid valve. A map showing the relationship between actual deceleration and vehicle speed threshold. The flowchart explaining the stop start control processing routine of this embodiment (first half part). The flowchart explaining the stop start control processing routine of this embodiment (second half part). The flowchart explaining the calculation processing routine of the inclination-angle of a road surface. (A) is a timing chart for explaining the operation state of the accelerator pedal, (b) is a timing chart for explaining a change in the WC pressure in the wheel cylinder, and (c) is a rear wheel when each linear solenoid valve is normal. A timing chart for explaining a change in speed, (d) a timing chart for explaining a change in the wheel speed of the rear wheel when the linear solenoid valve on the left rear wheel side is abnormal, and (e) a linear solenoid on the right rear wheel side. The timing chart explaining the change of the wheel speed of a rear wheel when a valve is abnormal, (f) is the timing chart explaining the change of the wheel speed of a rear wheel when each linear electromagnetic valve is abnormal. (A) is a timing chart explaining the change of the estimated vehicle body speed of the vehicle, (b) is a timing chart explaining the change of the actual deceleration of the vehicle, (c) is a timing chart explaining the change of the deceleration sensor value, (D) is a timing chart explaining the inclination angle of the road surface, (e) is a timing chart explaining the operation state of the accelerator pedal, (f) is a timing chart explaining the change of the brake switch, and (g) is an automatic transmission. (H) is a timing chart for explaining the change of the engine speed, (i) is a timing chart for explaining the wheel on the pressure reduction steep slope side, and (j) is a right rear wheel. FIG. 6K is a timing chart for explaining a change in the current value for the linear solenoid valve on the side, and FIG. Timing chart, (l) is a timing chart illustrating the change in pressure of the master cylinder and the wheel cylinder. The effect | action figure explaining the relationship of the force added to the vehicle which drive | works an uphill road. (A), (b), and (c) are timing charts explaining changes in vehicle body speed and braking force and timings at which the pump is operated in the prior art.

  Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. In the following description of the present specification, the traveling direction (forward direction) of the vehicle is assumed to be the front (front of the vehicle).

  As shown in FIG. 1, the vehicle according to the present embodiment includes a plurality of (four in the present embodiment) wheels (the right front wheel FR, the left front wheel FL, the right rear wheel RR, and the left rear wheel RL). , RL is a so-called rear wheel drive vehicle that functions as drive wheels. In such a vehicle, a driving force generator 13 having an engine 12 as a driving source that generates a driving force corresponding to the amount of operation of the accelerator pedal 11 by the driver, and a driving force generated by the driving force generator 13 are rearranged. And a driving force transmission device 14 for transmission to the wheels RR and RL. The vehicle is also provided with a braking device 16 for applying a braking force corresponding to the amount of operation of the brake pedal 15 by the driver to each wheel FR, FL, RR, RL.

  The driving force generator 13 includes a fuel injection device (not shown) that is disposed in the vicinity of an intake port (not shown) of the engine 12 and has an injector that injects fuel into the engine 12. The driving force generator 13 is driven based on control of an engine ECU 17 (also referred to as “engine electronic control device”) having a CPU, a ROM, a RAM, and the like (not shown). The engine ECU 17 is electrically connected to an accelerator opening sensor SE1 that is disposed in the vicinity of the accelerator pedal 11 and that detects an operation amount of the accelerator pedal 11 by the driver, that is, an accelerator opening. The engine ECU 17 calculates the accelerator opening based on the detection signal from the accelerator opening sensor SE1, and controls the driving force generator 13 based on the calculated accelerator opening.

  The driving force transmission device 14 includes a shift device 18 operated by a driver, a stepped automatic transmission that operates according to a shift range set by the shift device 18 and is connected to an output shaft of the engine 12. 19. Further, the driving force transmission device 14 is provided with a differential gear 20 that appropriately distributes the driving force transmitted from the output shaft of the automatic transmission 19 and transmits it to the rear wheels RR and RL. Therefore, in the present embodiment, the automatic transmission 19 and the differential gear 20 constitute a power transmission path for transmitting the driving force generated by the engine 12 to the rear wheels RR and RL.

  The shift device 18 includes a forward travel range (also referred to as “D range”), a reverse travel range (also referred to as “R range”), a neutral range (also referred to as “N range”), and a parking range (“P range”). A plurality of shift ranges including "." The D range includes an automatic shift mode that automatically changes the shift speed according to the estimated vehicle speed and acceleration of the vehicle, and a manual shift mode that changes the shift speed as intended by the driver through a shift operation by the driver. And are included. The N range and the P range are ranges for blocking the driving force from the engine 12 by the automatic transmission 19 and restricting the transmission of the driving force to the rear wheels RR and RL.

  The automatic transmission 19 includes a fluid-type driving force transmission mechanism having a torque converter, and a speed change mechanism having a plurality of forward shift speeds (for example, a 6th speed shift speed) and a reverse speed shift speed. This transmission mechanism is set to the engaged state when the shift range of the shift device 18 is the D range or the R range, and is released when the shift range of the shift device 18 is the N range or the P range. An input clutch 21 that is set to a state is provided. The input clutch 21 is operated by hydraulic control by a hydraulic adjustment unit (not shown). The driving force from the engine 12 is transmitted to the differential gear 20 via the fluid driving force transmission mechanism and the transmission mechanism when the input clutch 21 is in the engaged state, while the input clutch 21 is in the released state. In some cases, it is disconnected by the input clutch 21 of the transmission mechanism and is not transmitted to the differential gear 20.

  The driving force transmission device 14 is driven by control of an AT ECU 22 (also referred to as “AT electronic control device”) having a CPU, a ROM, a RAM, and the like (not shown). The AT ECU 22 appropriately controls the automatic transmission 19 and the differential gear 20 in accordance with the estimated vehicle speed of the vehicle, the operating conditions of the accelerator pedal 11, the brake pedal 15, and the shift device 18 by the driver.

  As shown in FIGS. 1 and 2, the braking device 16 includes a hydraulic pressure generating device 28 having a master cylinder 25, a booster 26 and a reservoir 27, and a brake actuator 31 having two hydraulic pressure circuits 29 and 30 (in FIG. 2). 2). The hydraulic circuits 29 and 30 are connected to the master cylinder 25 of the hydraulic pressure generator 28, respectively. A wheel cylinder 32a for the right front wheel FR and a wheel cylinder 32d for the left rear wheel RL are connected to the first hydraulic circuit 29, and a wheel for the left front wheel FL is connected to the second hydraulic circuit 30. A cylinder 32b and a wheel cylinder 32c for the right rear wheel RR are connected.

  In the hydraulic pressure generator 28, the booster 26 is connected to an intake manifold (not shown) of the engine 12, and a negative pressure is generated in the intake manifold when the engine 12 is driven. The booster 26 uses the pressure difference between the negative pressure generated in the intake manifold and the atmospheric pressure to boost the operating force of the brake pedal 15 by the driver. That is, the booster 26 of this embodiment is a booster that operates only when the engine 12 is driven.

  When the engine 12 is driven and the brake pedal 15 is operated by the vehicle driver, the master cylinder 25 and the booster 26 are activated. As a result, brake fluid as fluid is supplied from the master cylinder 25 into the wheel cylinders 32a to 32d via the hydraulic circuits 29 and 30, respectively. Then, a braking force corresponding to the wheel cylinder pressure (also referred to as “WC pressure”) in the wheel cylinders 32a to 32d is applied to each of the wheels FR, FL, RR, and RL.

  In the brake actuator 31, the hydraulic circuits 29 and 30 are connected to the master cylinder 25 via connection paths 33 and 34, respectively. The connection paths 33 and 34 include normally open linear solenoid valves (adjustments). Valves) 35a and 35b are provided. Each of these linear electromagnetic valves 35a and 35b includes a valve seat, a valve body, an electromagnetic coil, and a biasing member (for example, a coil spring) that biases the valve body in a direction away from the valve seat. Are displaced in accordance with a current value supplied to an electromagnetic coil from a brake ECU 55 described later. That is, the WC pressure in the wheel cylinders 32a to 32d is maintained at a hydraulic pressure corresponding to the current value supplied to the linear electromagnetic valves 35a and 35b.

  The first hydraulic circuit 29 includes a right front wheel path 36a connected to the wheel cylinder 32a and a left rear wheel path 36d connected to the wheel cylinder 32d. The second hydraulic circuit 30 includes a left front wheel path 36b connected to the wheel cylinder 32b and a right rear wheel path 36c connected to the wheel cylinder 32c. Therefore, in the present embodiment, a flow path that connects the master cylinder 25 and the wheel cylinders 32a to 32d is configured by the connection paths 33 and 34 and the paths 36a to 36d. Further, in each of the paths 36a to 36d, pressure increasing valves 37a, 37b, 37c, and 37d that are normally open electromagnetic valves that are operated when restricting the increase in the WC pressure in the wheel cylinders 32a to 32d, and the WC pressure are provided. There are provided pressure reducing valves 38a, 38b, 38c, 38d, which are normally closed electromagnetic valves that are operated when the pressure is reduced.

  The hydraulic pressure circuits 29 and 30 are operated based on the rotation of the motor 41 and reservoirs 39 and 40 for temporarily storing brake fluid flowing out from the wheel cylinders 32a to 32d via the pressure reducing valves 38a to 38d. Pumps 42 and 43 are connected to each other. The reservoirs 39 and 40 are connected to the pumps 42 and 43 via the suction flow paths 44 and 45, respectively, and are connected to the linear electromagnetic valves 35a and 35b in the connection paths 33 and 34 via the master side flow paths 46 and 47. Are connected to the master cylinder 25 side. The pumps 42 and 43 are connected to connection portions 50 and 51 between the pressure increasing valves 37a to 37d and the linear electromagnetic valves 35a and 35b in the hydraulic pressure circuits 29 and 30 through supply channels 48 and 49, respectively. Has been. When the motor 41 rotates, each of the pumps 42 and 43 sucks brake fluid from the reservoirs 39 and 40 and the master cylinder 25 through the suction channels 44 and 45 and the master channels 46 and 47, respectively. Then, the brake fluid is discharged into the supply channels 48 and 49, respectively.

Next, the brake ECU 55 (also referred to as “brake electronic control device”) that controls the drive of the brake actuator 31 will be described.
As shown in FIG. 2, the input interface of the brake ECU 55 has wheel speed sensors SE2, SE3, SE4, SE5 for detecting the wheel speeds of the wheels FR, FL, RR, RL, in the longitudinal direction of the vehicle. An acceleration sensor SE6 for detecting the vehicle deceleration is electrically connected. Further, a brake switch SW1 that is disposed in the vicinity of the brake pedal 15 and detects whether or not the brake pedal 15 is operated is electrically connected to the input side interface of the brake ECU 55. On the other hand, the valves 35a, 35b, 37a to 37d, 38a to 38d, the motor 41, and the like are electrically connected to the output side interface of the brake ECU 55. The acceleration sensor SE6 outputs a signal that is positive because the center of gravity of the vehicle moves backward when the vehicle accelerates, while the center of gravity of the vehicle decelerates when the vehicle decelerates. A signal that is negative to move forward is output.

  The brake ECU 55 includes a digital computer including a CPU, ROM and RAM (not shown), a valve driver circuit (not shown) for operating the valves 35a, 35b, 37a to 37d, and 38a to 38d, and the motor 41. A motor driver circuit (not shown) for operating the motor. In the ROM of the digital computer, various control processes (such as a stop / start control process described later), various maps (such as the maps shown in FIGS. 3 and 4), various thresholds (elapsed time thresholds, reference values, etc. described later), and the like are stored in advance. It is remembered. The RAM stores various information (wheel speed, estimated vehicle speed, actual deceleration, deceleration sensor value, calculated tilt angle, tilt angle, which will be described later) while an ignition switch (not shown) of the vehicle is on. , Elapsed time, predetermined time, flags, abnormality counter, etc.) are stored.

Next, various maps stored in the ROM of the brake ECU 55 will be described with reference to FIGS.
First, the first map shown in FIG. 3 is a map showing the relationship between the WC pressure Pwc in the wheel cylinders 32a to 32d and the current value Isl supplied to the electromagnetic coils of the linear electromagnetic valves 35a and 35b. As shown in FIG. 3, the current value Isl is set to a larger value as the WC pressure Pwc in the wheel cylinders 32a to 32d is set to a higher value. That is, when the WC pressure Pwc is set to “0 (zero)”, the current value Isl is set to the minimum current value Imin. When a current value Isl larger than the minimum current value Imin is supplied to the linear electromagnetic valves 35a and 35b, the valve bodies of the linear electromagnetic valves 35a and 35b approach the valve body against the urging force from the urging member. Displace as much as possible. On the other hand, the WC pressure Pwc is a maximum hydraulic pressure Pwc1 (> 0 (zero) as a set fluid pressure that can maintain the stop of the vehicle even when the assumed inclination angle of the road surface is maximum (for example, 30 degrees). )), The current value Isl is set to the maximum current value Imax.

  Next, the second map shown in FIG. 4 is a map showing the relationship between the actual deceleration DVS of the vehicle and the vehicle body speed threshold value KVS. The actual deceleration DVS is a value calculated based on the estimated vehicle body speed, which will be described in detail later, and is a value that can be acquired without using the acceleration sensor SE6. As shown in FIG. 4, when the actual deceleration DVS is “0 (zero)”, the vehicle body speed threshold value KVS is set to the first speed value KVS1 (for example, 5 km / h). When the actual deceleration DVS is greater than “0 (zero)” and less than the predetermined deceleration DVS1, the vehicle body speed threshold value KVS is set to a larger value as the actual deceleration DVS is larger. When the actual deceleration DVS is equal to or greater than the predetermined deceleration DVS1, the vehicle body speed threshold value KVS is set to the second speed value KVS2 (for example, 10 km / h).

  In addition, the automatic transmission 19 of this embodiment has a torque converter. Therefore, when the shift range of the shift device 18 is the D range, when the accelerator pedal 11 and the brake pedal 15 are not operated, the creep force based on the creep phenomenon is transmitted to the rear wheels RR and RL that are drive wheels. The In this case, the vehicle located on the horizontal road surface travels at a speed corresponding to the first speed value KVS1 (that is, about 5 km / h).

  In the vehicle of this embodiment, the engine ECU 17, the AT ECU 22, and the brake ECU 55 are connected to each other via a bus 56 so that various information and various control commands can be transmitted and received as shown in FIG. For example, the engine ECU 17 appropriately transmits information related to the accelerator opening of the accelerator pedal 11 to the brake ECU 55, while the brake ECU 55 sends a control command to stop driving the engine 12 or the engine 12. A control command for re-driving is transmitted to the engine ECU 17. The AT ECU 22 transmits information about the shift range of the shift device 18 and the gear position of the automatic transmission 19 to the brake ECU 55, while the brake ECU 55 sends the input clutch 21 of the automatic transmission 19. A control command or the like for activation is transmitted to the AT ECU 22. Therefore, in this embodiment, each ECU 17, 22, 55 constitutes a control means.

  Next, among the ECUs 17, 22, and 55, the stop / start control processing routine executed by the brake ECU 55 that functions as the main ECU in the present embodiment, the flowchart shown in FIGS. 5 to 7, and FIGS. Will be described based on the timing chart shown in FIG. FIG. 8 is a timing chart when the vehicle starts on an uphill road.

  Now, the brake ECU 55 executes a stop / start control processing routine at predetermined intervals (for example, a cycle of 0.01 seconds). In this stop / start control processing routine, the brake ECU 55 acquires the wheel speed VW of each wheel FR, FL, RR, RL based on the detection signals from the wheel speed sensors SE2 to SE5 (step S10). Subsequently, the brake ECU 55 acquires an estimated vehicle body speed VS based on at least one wheel speed VW among the wheel speeds VW acquired in step S10, and time-differentiates the estimated vehicle body speed VS with respect to the differential result. Then, the actual deceleration DVS is obtained by integrating "-1" (step S11). Therefore, in this embodiment, step S11 corresponds to a deceleration acquisition step. Then, the brake ECU 55 acquires information related to the accelerator opening of the accelerator pedal 11 from the engine ECU 17 (step S12), and acquires information related to the shift range of the shift device 18 from the AT ECU 22 (step S13). Subsequently, the brake ECU 55 calculates the vehicle body acceleration of the vehicle based on the detection signal from the acceleration sensor SE6, and obtains the deceleration sensor value G by adding "-1" to the vehicle body acceleration (step). S14). The deceleration sensor value G is a vehicle body deceleration calculated based on the acceleration sensor SE6, and is a positive value when the vehicle is decelerated. The deceleration sensor value G indicates a negative value when the vehicle stops on an uphill road, because the center of gravity of the vehicle moves backward compared to when the road surface is a horizontal road, while the vehicle is falling. When stopping on a slope, the center of gravity of the vehicle moves forward compared to when the road surface is a horizontal road, indicating a positive value.

  Then, the brake ECU 55 performs a calculation process of the road surface inclination angle θ, which will be described in detail with reference to FIG. 7 (step S15). Subsequently, the brake ECU 55 determines whether or not an eco-run control permission flag FLG1 described later is OFF (step S16). This eco-run control permission flag FLG1 is reset to OFF when the ignition switch of the vehicle is turned ON. If the determination result in step S16 is affirmative (FLG1 = OFF), the brake ECU 55 is satisfied that the vehicle is stopped, the accelerator pedal 11 is OFF, and the brake switch SW1 is ON. It is determined whether or not (step S17). Specifically, the brake ECU 55 determines whether or not the vehicle is stopped based on the estimated vehicle speed VS acquired in step S11, and the accelerator opening received from the engine ECU 17 is “0 (zero)”. In some cases, it is determined that the accelerator pedal 11 is OFF.

  If the determination result in step S17 is affirmative, the brake ECU 55 executes brake holding control because all the above three conditions are satisfied (step S18). Specifically, the brake ECU 55 calculates the WC pressure Pwc in the wheel cylinders 32a to 32d corresponding to the inclination angle θ of the road surface on which the vehicle stops based on the following relational expression (formula 1). Note that the inclination angle θ that is substituted into the relational expression (Expression 1) is the inclination angle acquired in step S15.

Pwc = A × (the absolute value of θ) (Formula 1)
However, A is a constant for converting the inclination angle into the WC pressure. Next, the brake ECU 55 sets the current value Isl corresponding to the calculated WC pressure Pwc based on the first map shown in FIG. The current value Isl is supplied to the electromagnetic coils of the linear electromagnetic valves 35a and 35b. As a result, the WC pressure in each of the wheel cylinders 32a to 32d is adjusted to a pressure close to the WC pressure Pwc calculated by the relational expression (Expression 1). Therefore, even when the operation of the driver's brake pedal 15 is canceled, the braking force for each wheel FR, RL, RR, RL is maintained, and the movement of the vehicle unintended by the driver is suppressed. Therefore, in this embodiment, step S18 corresponds to a fluid pressure reduction suppression step. Thereafter, the brake ECU 55 once ends the stop / start control processing routine.

  On the other hand, if the determination result in step S17 is negative, the brake ECU 55 is in the process of holding the brake and the accelerator pedal 11 is ON because at least one of the three conditions is not satisfied. It is determined whether or not (step S19). Specifically, the brake ECU 55 determines that the accelerator pedal 11 is ON when the accelerator opening degree received from the engine ECU 17 is not “0 (zero)”. If the determination result in step S19 is negative, the brake ECU 55 has no intention to start the vehicle because the brake holding control is being performed and at least one of the accelerator pedal 11 is not established. The stop / start control processing routine is temporarily terminated.

  On the other hand, if the determination result in step S19 is affirmative (the brake holding control is being performed and the accelerator pedal 11 is ON), the brake ECU 55 determines that the driver is willing to start the vehicle and holds the brake. The cancellation control is executed (step S20). In the brake holding elimination control, the pressure reduction speed of the WC pressure Pwc in the wheel cylinders 32 a and 32 d connected to the first hydraulic pressure circuit 29 and the WC pressure in the wheel cylinders 32 b and 32 c connected to the second hydraulic pressure circuit 30. Each linear electromagnetic valve 35a, 35b is operated so that the pressure reduction speed of Pwc is different. Specifically, the brake ECU 55 identifies which one of the rear wheels RR and RL, which are drive wheels, is a wheel on the decompression steep slope side. In the initial state, the left rear wheel RL is set as a wheel on the reduced pressure steep slope side. Subsequently, the brake ECU 55 sets the pressure reduction speed of the WC pressure Pwc in the wheel cylinder (for example, the wheel cylinder 32d) for the wheel (for example, the left rear wheel RL) on the pressure reduction steep slope side to the first pressure reduction speed. Further, the brake ECU 55 reduces the pressure reduction speed of the WC pressure Pwc in the wheel cylinder (for example, the wheel cylinder 32c) for the wheel on the pressure reduction gentle gradient side (for example, the right rear wheel RR), which is lower than the first pressure reduction speed. Set to 2 decompression speed. As an example, the second decompression speed is set to about 1/5 times the first decompression speed. Then, the brake ECU 55 uses the current value Isl supplied to the electromagnetic coils of the linear electromagnetic valves 35a and 35b so that the WC pressure Pwc in each of the wheel cylinders 32a to 32d is reduced at an individually set pressure reduction speed. Reduce individually.

  Subsequently, the brake ECU 55 determines whether or not an elapsed time after the start of the reduction of the WC pressure Pwc in each of the wheel cylinders 32a to 32d by the brake holding cancellation control has passed a predetermined time KT1 (step S21). ). This predetermined time KT1 is slightly smaller than the time from when the WC pressure Pwc in the wheel cylinder corresponding to the wheel on the pressure reduction steep slope side starts to decrease until the WC pressure Pwc becomes “0 (zero)”. It is a time obtained by adding a long time (for example, 0.01 seconds). That is, the predetermined time KT1 is set to be longer as the current value Isl supplied to the electromagnetic coils of the linear electromagnetic valves 35a and 35b immediately before the brake holding cancellation control is started. If the determination result in step S21 is negative (elapsed time <predetermined time KT1), the brake ECU 55 repeatedly executes the determination process in step S21 until the determination result in step S21 is affirmative.

  If the determination result in step S21 is affirmative (elapsed time ≧ predetermined time KT1), the brake ECU 55 determines that the wheel speed VW of the wheel on the reduced pressure steep slope side (for example, the left rear wheel RL) is reduced gradually. It is determined whether the speed is higher than the wheel speed VW of the side wheel (for example, the right rear wheel RR) (step S22). The wheel speeds VW of the wheel on the reduced pressure steep slope (for example, the left rear wheel RL) and the wheel on the reduced pressure gentle gradient side (for example, the right rear wheel RR) are the wheel speeds of the rear wheels RR and RL acquired in step S10. VW. Therefore, in this embodiment, steps S20, S21, and S22 correspond to an abnormality determination step.

  Here, the change in the WC pressure Pwc in each of the wheel cylinders 32a to 32d and the wheel speed VW of each of the rear wheels RR and RL from when the accelerator pedal 11 is turned on until the elapsed time becomes equal to or longer than the predetermined time KT1. The relationship with the change will be described with reference to the timing chart shown in FIG. Here, a case will be described in which the wheel on the reduced pressure steep slope side is the left rear wheel RL and the wheel on the reduced pressure gentle slope side is the right rear wheel RR. FIG. 8C is a timing chart showing changes in the wheel speed VW of the rear wheels RR and RL when both the linear solenoid valves 35a and 35b are normally operated. FIG. It is a timing chart which shows the change of the wheel speed VW of each rear wheel RR and RL when the linear electromagnetic valve 35a by the side of the rear wheel RL is abnormal. FIG. 8E is a timing chart showing changes in the wheel speeds VW of the rear wheels RR and RL when the linear solenoid valve 35b on the right rear wheel RR side is abnormal, and FIG. 4 is a timing chart showing changes in wheel speeds VW of rear wheels RR and RL when both linear solenoid valves 35a and 35b are abnormal. By the way, the abnormality of the linear solenoid valve in this embodiment is a state where the valve body of the linear solenoid valve does not move normally (a state where the valve body hits something and does not move as intended (stick)) or a seal failure due to foreign object inclusion. The state in which the WC pressure Pwc cannot be properly maintained even when the valve body is seated on the valve seat. The concept of abnormality of the linear electromagnetic valve includes a failure of the linear electromagnetic valve itself and a short circuit of an electric wire for supplying current to the electromagnetic coil of the linear electromagnetic valve.

  That is, as shown in FIGS. 8A and 8B, when the accelerator pedal 11 is turned from OFF to ON at the first timing t11, the WC pressure in the wheel cylinders 32a and 32d for the right front wheel FR and the left rear wheel RL is determined. Pwc is depressurized at the first depressurization rate. On the other hand, the WC pressure Pwc in the wheel cylinders 32b and 32c for the left front wheel FL and the right rear wheel RR is reduced at the second pressure reduction speed (<first pressure reduction speed). At this time, if the linear solenoid valves 35a and 35b are both normal, as shown in FIGS. 8B and 8C, the WC pressure Pwc in the wheel cylinders 32a and 32d for the right front wheel FR and the left rear wheel RL is obtained. The wheel speed VW of the left rear wheel RL becomes a value larger than “0 (zero)” at the second timing t12 when becomes “0 (zero)”, and the wheel speed VW of the left rear wheel RL thereafter becomes the time It becomes faster as time passes. In this case, the wheel speed VW of the left rear wheel RL is substantially the same as the estimated vehicle body speed VS of the vehicle. However, when the amount of operation of the accelerator pedal 11 by the driver is large, the wheel speed VW of the left rear wheel RL may become larger than “0 (zero)” before the second timing t12.

  On the other hand, at the second timing t12, the right rear wheel RR is given a braking force according to the WC pressure Pwc in the wheel cylinder 32c for the right rear wheel RR. The wheel speed VW is “0 (zero)”. Then, at the third timing t13 when the predetermined time KT1 has elapsed since the first timing t11, the wheel speed VW of the right rear wheel RR remains “0 (zero)”. At this time, if the amount of operation of the accelerator pedal 11 is large, the wheel speed VW of the right rear wheel RR may be higher than “0 (zero)” at the third timing t13. However, even in this case, the braking force is not applied to the left rear wheel RL, while the braking force is applied to the right rear wheel RR. Therefore, the wheel speed VW of the left rear wheel RL is greater to the right. It becomes faster than the wheel speed VW of the rear wheel RR.

  Thereafter, when the fourth timing t14 when the WC pressure Pwc in the wheel cylinder 32c becomes “0 (zero)” has elapsed, the braking force is not applied to the right rear wheel RR. Therefore, the wheel speed VW of the right rear wheel RR increases rapidly to catch up with the wheel speed VW of the left rear wheel RL. Then, at the fifth timing t15, the wheel speed VW of the right rear wheel RR becomes substantially equal to the wheel speed VW of the left rear wheel RL. In the present embodiment, from the third timing t13 onward, the pressure reduction speed of the WC pressure Pwc in the wheel cylinder 32c on the right rear wheel RR side is greater than the first pressure reduction speed from the second pressure reduction speed. The pressure reduction speed is changed to 3.

  When only the linear solenoid valve 35a on the left rear wheel RL side is abnormal, the WC pressure Pwc in the wheel cylinder 32d for the left rear wheel RL is braked as shown by a two-dot chain line in FIG. It becomes “0 (zero)” when the operation of the pedal 15 is canceled or immediately after. That is, no braking force is applied to the left rear wheel RL at the first timing t11. Therefore, as shown in FIG. 8D, after the first timing t11, the wheel speed VW of the left rear wheel RL becomes higher as time passes. On the other hand, since the linear solenoid valve 35b on the right rear wheel RR side is normal, the wheel speed VW of the right rear wheel RR is the fourth timing t14 when the WC pressure Pwc in the wheel cylinder 32c becomes “0 (zero)”. From the left rear wheel RL so as to catch up with the wheel speed VW.

  If only the linear solenoid valve 35b on the right rear wheel RR side is abnormal, the WC pressure Pwc in the wheel cylinder 32c for the right rear wheel RR is braked as shown by a two-dot chain line in FIG. It becomes “0 (zero)” when the operation of the pedal 15 is canceled or immediately after. That is, no braking force is applied to the right rear wheel RR at the first timing t11. Therefore, as shown in FIG. 8E, after the first timing t11, the wheel speed VW of the right rear wheel RR becomes higher as time passes. At this time, the estimated vehicle body speed VS of the vehicle is substantially the same as the wheel speed VW of the right rear wheel RR. On the other hand, since the linear solenoid valve 35a on the left rear wheel RL side is normal, the wheel speed VW of the left rear wheel RL increases rapidly to catch up with the wheel speed VW of the right rear wheel RR after the second timing t12. . Therefore, at the third timing t13, the wheel speed VW of the right rear wheel RR becomes higher than the wheel speed VW of the left rear wheel RL.

  When both linear solenoid valves 35a and 35b are abnormal, the WC pressure Pwc in the wheel cylinders 32c and 32d of the rear wheels RR and RL is braked as shown by the two-dot chain line in FIG. It becomes “0 (zero)” at the time when the operation of the pedal 15 is canceled or immediately after. That is, the braking force is not applied to the rear wheels RR and RL at the first timing t11. Therefore, as shown in FIG. 8 (f), after the first timing t11, the wheel speeds VW of the rear wheels RR and RL become higher with time. In this case, at the third timing t13, the wheel speed VW of the right rear wheel RR becomes substantially equal to the wheel speed VW of the left rear wheel RL.

  In the case where the depressurized steep slope side wheel is the right rear wheel RR and the depressurized gentle gradient side wheel is the left rear wheel RL, when each of the linear solenoid valves 35a and 35b is normal, the fourth timing is set. At t14, the wheel speed VW of the right rear wheel RR becomes higher than the wheel speed VW of the left rear wheel RL. Further, when only the linear solenoid valve 35a on the left rear wheel RL side is abnormal, the wheel speed VW of the left rear wheel RL becomes higher than the wheel speed VW of the right rear wheel RR at the fourth timing t14.

  Returning to FIG. 5, when the determination result of step S22 is negative, that is, when the wheel speed of the wheel on the pressure reduction steep slope side ≦ the wheel speed of the wheel on the pressure reduction gentle gradient side, the brake ECU 55 Of 35a and 35b, it is determined that at least a linear solenoid valve (for example, the linear solenoid valve 35b) for a wheel (for example, the right rear wheel RR) on the reduced pressure gentle gradient side may be abnormal. Then, the brake ECU 55 increments the abnormality counter CI by “1” (step S23), and determines whether or not the abnormality counter CI updated in step S23 is greater than or equal to a preset count threshold KCI (for example, 3). (Step S24). This count threshold value KCI is a threshold value set because there is a possibility of erroneous determination when there is a linear solenoid valve that indicates an abnormality by only one determination process. If the determination result of step S24 is affirmative (CI ≧ KCI), the brake ECU 55 executes an abnormality detection process (step S25). Specifically, the brake ECU 55 informs the driver that there is a linear solenoid valve indicating abnormality in each of the linear solenoid valves 35a and 35b, and prohibits execution of a clutch disconnection process and an engine stop process described later. To do. Thereafter, the brake ECU 55 sets the eco-run control permission flag FLG1 to OFF (step S26), and once ends the stop / start control processing routine. On the other hand, when the determination result of step S24 is negative (CI <KCI), the brake ECU 55 once ends the stop / start control process routine after executing the process of step S26.

  On the other hand, if the determination result in step S22 is affirmative, that is, if the wheel speed of the wheel on the decompression steep slope side> the wheel speed of the wheel on the decompression gentle slope side, the brake ECU 55 causes the linear solenoid valves 35a and 35b to It is determined whether or not the check has been completed (step S27). When this determination result is a negative determination, the brake ECU 55 changes the wheel on the pressure reduction steep slope side and sets the abnormality counter CI to “abnormal counter CI” in order to check the linear solenoid valve that has not been checked yet. It is reset to “0 (zero)” (step S28). For example, when the wheel on the reduced pressure steep slope side this time is the left rear wheel RL, the brake ECU 55 changes the next reduced pressure steep side wheel to the right rear wheel RR. Thereafter, the brake ECU 55 once ends the stop / start control processing routine. On the other hand, if the determination result in step S27 is affirmative, the brake ECU 55 sets the eco-run control permission flag FLG1 to ON and sets the abnormality counter CI to "" because the linear solenoid valves 35a and 35b are both normal. It is reset to “0 (zero)” (step S29), and the stop / start control processing routine is once ended.

  On the other hand, when the determination result in step S16 is negative (FLG1 = ON), the brake ECU 55 performs the vehicle body speed threshold corresponding to the actual deceleration DVS acquired in step S11 as shown in the flowchart of FIG. KVS is set based on the second map shown in FIG. 4 (step S30). Therefore, in this embodiment, step S30 corresponds to a threshold setting step. Subsequently, the brake ECU 55 determines that the estimated vehicle speed VS is equal to or less than the vehicle speed threshold KVS, the accelerator pedal 11 is OFF, the brake switch SW1 is ON, and the actual deceleration DVS is “0 (zero)”. It is determined whether or not everything greater than "is established (step S31). The estimated vehicle speed VS, actual deceleration DVS, and vehicle speed threshold value KVS used in step S31 are values acquired in the processes of steps S11 and S30.

  If the determination process in step S31 is affirmative, the brake ECU 55 executes clutch disconnection control (transmission efficiency lowering control) because all the four conditions are satisfied (step S32). Specifically, the brake ECU 55 sends a control command to the AT ECU 22 to release the input clutch 21 of the automatic transmission 19. Then, the AT ECU 22 performs hydraulic control to bring the input clutch 21 into a released state, and when the hydraulic control is completed, the AT ECU 22 transmits to the brake ECU 55 that the input clutch 21 has been released. When the brake ECU 55 receives that the input clutch 21 has been released, the brake ECU 55 proceeds to step S36 described later. Therefore, in this embodiment, step S32 corresponds to an efficiency reduction step.

  Here, as shown in FIGS. 9A, 9B, 9C, and 9D, when the estimated vehicle speed VS of the vehicle traveling on the uphill road is a constant speed, the calculation is performed based on the estimated vehicle speed VS. The actual deceleration DVS is substantially “0 (zero)”, and the deceleration sensor value G acquired using the acceleration sensor SE6 is a negative value (first timing t21). The reason why the deceleration sensor value G is a negative value is that, as shown in FIG. 10, a vehicle traveling on an uphill road is a force based on the gravity g applied to the vehicle body (a downward force on the slope, It is also referred to as “gravity equivalent force.”) This is because Fg acts and the gravity center force Fg tends to move the center of gravity of the vehicle backward. Further, the gravity equivalent force Fg increases as the road surface inclination angle θ increases.

  Then, as shown in FIGS. 9A and 9E, after the second timing t22 when the operation of the accelerator pedal 11 by the driver is canceled, the engine 12 transmits the driving wheel to the rear wheels RR and RL. Since the driving force Fd (see FIG. 10) becomes smaller, the estimated vehicle body speed VS of the vehicle on which the gravity equivalent force Fg acts gradually decreases. Then, the actual deceleration DVS and the deceleration sensor value G become larger values than before the second timing t22. In the present embodiment, the actual deceleration DVS and the deceleration sensor value G are positive values. When the driver starts operating the brake pedal 15 at the third timing t23 thereafter, the brake switch SW1 is turned from OFF to ON as shown in FIG. 9 (f).

  Then, at the fourth timing t24 when the estimated vehicle body speed VS of the vehicle becomes equal to or less than the vehicle body speed threshold value KVS set based on the actual deceleration DVS, as shown in FIGS. 9 (a) and 9 (g), the automatic transmission 19 Clutch disengagement control is started to change the gear position from the current gear position (in this case, the second gear position (2nd)) to neutral. When the clutch disengagement control is executed, the input clutch 21 of the automatic transmission 19 is changed from the engaged state to the disengaged state, and the power transmission from the engine 12 to the rear wheels RR and RL is interrupted. Then, the force for moving the vehicle forward does not act on the vehicle. Note that the timing at which the input clutch 21 is actually released is slightly delayed from the fourth timing t24. This is because of a response delay due to the input clutch 21 being operated by hydraulic control.

  When the clutch disengagement control is executed in this way, the engine 12 does not transmit stress to the rear wheels RR and RL. The driving force transmitted from the engine 12 to the rear wheels RR and RL is a force in the opposite direction to the reverse of the vehicle not intended by the driver. Therefore, the driver of the vehicle increases the operation amount of the brake pedal 15 before the vehicle stops by an amount corresponding to the decrease in the driving force transmitted to the rear wheels RR and RL, thereby suppressing unintended reverse movement of the vehicle. Then, the master cylinder pressure (hereinafter also referred to as “MC pressure”) Pmc of the master cylinder 25 is increased, and the WC pressure Pwc in each of the wheel cylinders 32a to 32d is increased following the MC pressure Pmc. Pressed. As a result, the braking force for each wheel FR, FL, RR, RL is increased.

  Returning to FIG. 6, when the determination result in step S31 is negative, the brake ECU 55 determines that at least one of the four conditions is not satisfied, and an engine stop flag FLG2 described later is OFF. Is determined (step S33). If this determination result is a negative determination (FLG2 = ON), the brake ECU 55 proceeds to step S36 described later. On the other hand, when the determination result of step S33 is affirmative (FLG2 = OFF), the brake ECU 55 determines whether or not the accelerator pedal 11 is ON (step S34). If the determination result is affirmative (accelerator pedal 11 = ON), the brake ECU 55 determines that the driver intends to accelerate the vehicle, and executes first clutch connection control (step S35). Specifically, the brake ECU 55 puts the input clutch 21 of the automatic transmission 19 into the engaged state, and changes the gear position of the automatic transmission 19 to the gear position before the clutch disengagement control (in the case of FIG. 2), a control command indicating that the second gear is to be transmitted is transmitted to the AT ECU 22. Then, the AT ECU 22 controls the hydraulic pressure so that the input clutch 21 is engaged and sets the gear position to the second gear position. When the hydraulic pressure control is completed, the AT ECU 22 transmits a notification to that effect to the brake ECU 55. To do. When the brake ECU 55 receives that the hydraulic control is completed, the brake ECU 55 once ends the stop / start control processing routine. On the other hand, when the determination result of step S34 is negative (accelerator pedal 11 = OFF), the brake ECU 55 proceeds to the next step S36.

  In step S36, the brake ECU 55 performs a determination process equivalent to that in step S17. If the determination result is affirmative, the brake ECU 55 is satisfied that the vehicle is stopped, the accelerator pedal 11 is OFF, and the brake switch SW1 is ON. Equivalent brake holding control (braking force holding control) is executed (step S37). Therefore, in the present embodiment, step S37 corresponds to a braking force holding step and a fluid pressure reduction suppression step for maintaining the braking force on the wheels FR, FL, RR, and RL after the vehicle is stopped based on the brake operation by the driver. .

  Then, the brake ECU 55 executes the engine stop control and the second clutch connection control after the operation of each of the linear electromagnetic valves 35a and 35b is completed by the brake holding control (step S38). Specifically, the brake ECU 55 transmits a control command for stopping the engine 12 to the engine ECU 17. Then, the engine ECU 17 stops the engine 12 by, for example, stopping the supply of fuel to the engine 12. Then, when the engine 12 is stopped, the engine ECU 17 transmits a message to that effect to the brake ECU 55. Therefore, in this embodiment, step S38 (engine stop control) corresponds to a drive source stop step executed after the braking force maintaining step (step S37). Further, the brake ECU 55 sends a control command to the AT ECU 22 to bring the input clutch 21 of the automatic transmission 19 into the engaged state and to change the shift stage of the automatic transmission 19 to the first shift stage (1st). To do. Then, the AT ECU 22 controls the hydraulic pressure so that the input clutch 21 is engaged and the gear position is changed to the first gear position. When the hydraulic pressure control is completed, the AT ECU 22 transmits a message to that effect to the brake ECU 55. To do. Therefore, in this embodiment, step S38 (second clutch connection control) restores the efficiency of operating the input clutch 21 so that the transmission efficiency of the driving force Fd to the rear wheels RR and RL approaches the execution before the clutch disengagement control. It corresponds to a step. The brake ECU 55 receives the fact that the engine 12 has been stopped from the engine ECU 17 and the engine ECU 17 when the fact that the gear position of the automatic transmission 19 is set to the first gear position from the AT ECU 22. The stop flag FLG2 is set to ON (step S39), and the stop / start control processing routine is temporarily ended.

  Here, as shown in FIG. 9A, at the fifth timing t25 when the vehicle stops, the brake pedal SW1 is turned on and the brake holding control is started because the accelerator pedal 11 is turned off and the brake switch SW1 is turned on. That is, as shown in FIGS. 9 (j) and 9 (k), current values Isl corresponding to the inclination angle θ of the road surface on which the vehicle stops are respectively supplied to the electromagnetic coils of the linear electromagnetic valves 35a and 35b. When each linear electromagnetic valve 35a, 35b is operated based on such current value Isl, even if the operation of the brake pedal 15 by the driver is canceled, the braking force for each wheel FR, FL, RR, RL is maintained, respectively. As a result, the backward movement of the vehicle is suppressed.

  Thereafter, at the sixth timing t26, engine stop control and second clutch connection control are executed. At this time, as shown in FIG. 9G, the seventh timing t27 at which the shift stage of the automatic transmission 19 is changed from the neutral to the first shift stage is slightly delayed from the sixth timing t26. This is because of a response delay caused by a plurality of elements including the input clutch 21 being operated by hydraulic control in the automatic transmission 19. Further, as shown in FIG. 9 (h), the eighth timing t28 at which the engine actually stops is slightly delayed from the sixth timing t26. This is because it takes some time until the driving force is not generated in the engine 12 after the fuel supply to the engine 12 is stopped.

  Returning to FIG. 6, when the determination result of step S36 is negative, the brake ECU 55 is at least one of the fact that the vehicle is stopped, the accelerator pedal 11 is OFF, and the brake switch SW1 is ON. Since one is not established, it is determined whether or not the engine stop flag FLG2 is ON (step S40). When this determination result is a negative determination (FLG2 = OFF), the brake ECU 55 determines that the brake holding control, the engine stop control, and the second clutch connection control have not been executed, and ends the stop / start control processing routine once. To do. On the other hand, if the determination result in step S40 is affirmative (FLG2 = ON), the brake ECU 55 resets the engine stop flag FLG2 to OFF (step S41) and executes engine restart control (step S42). Specifically, the brake ECU 55 transmits a control command for restarting the engine 12 to the engine ECU 17. Then, the engine ECU 17 controls the driving force generation device 13 to start the engine 12, and when the engine 12 actually starts to start (that is, when driving force Fd starts to be generated from the engine 12), this is indicated. It transmits to ECU55 for brakes. When the brake ECU 55 receives from the engine ECU 17 that the engine 12 has actually started, it terminates the engine restart control.

  Subsequently, the brake ECU 55 acquires information on the accelerator opening of the accelerator pedal 11 from the engine ECU 17, and determines whether or not the accelerator pedal 11 is ON based on the acquisition result (step S43). When this determination result is a negative determination (accelerator pedal 11 = OFF), the brake ECU 55 repeatedly executes the determination process of step S43 until the determination result of step S43 becomes a positive determination. If the determination result in step S43 is affirmative (accelerator pedal 11 = ON), the brake ECU 55 executes clutch shift control (step S44). Specifically, the brake ECU 55 transmits to the AT ECU 22 that the gear position of the automatic transmission 19 is changed as necessary. Then, when the shift range of the shift device 18 is the D range and the manual shift mode, the AT ECU 22 acquires the currently selected shift stage (for example, the second shift stage), and the automatic transmission. The 19 gears are changed to the selected gear. At this time, the AT ECU 22 does not change the shift stage of the automatic transmission 19 when the selected shift stage is the first shift stage. The AT ECU 22 does not change the gear position of the automatic transmission 19 even when the shift range of the shift device 18 is the D range and the automatic transmission mode is set. Further, the AT ECU 22 does not change the gear position of the automatic transmission 19 even when the shift range of the shift device 18 is other than the D range.

  Subsequently, the brake ECU 55 performs brake holding cancellation control equivalent to step S20 (step S45). Then, the brake ECU 55 performs the same determination process as in step S21 (step S46). If this determination result is a negative determination (elapsed time <predetermined time KT1), the brake ECU 55 repeatedly executes the determination process of step S46 until the determination result of step S46 becomes a positive determination.

  If the determination result in step S46 is affirmative (elapsed time ≧ predetermined time KT1), the brake ECU 55 performs determination processing similar to that in step S22 (step S47). Therefore, in this embodiment, steps S45, S46, and S47 constitute an abnormality determination step for determining whether or not there is a linear electromagnetic valve indicating abnormality among the linear electromagnetic valves 35a and 35b. When the determination result of step S47 is negative, that is, when the wheel speed of the wheel on the pressure reduction steep slope side ≦ the wheel speed of the wheel on the pressure reduction gentle gradient side, the brake ECU 55 includes the linear solenoid valves 35a and 35b. It is determined that there is a possibility that at least the linear solenoid valve for the wheel on the slow pressure-gradient side is abnormal. Then, the brake ECU 55 sets the eco-run control permission flag FLG1 to OFF (step S48), and once ends the stop / start control processing routine. On the other hand, if the determination result of step S47 is affirmative, that is, if the wheel speed of the wheel on the reduced pressure steep slope side> the wheel speed of the wheel on the reduced pressure gentle gradient side, the brake ECU 55 is for the wheel on the reduced pressure gentle gradient side. Since the linear solenoid valve is normal, the depressurized steep slope side wheel is changed as in step S28 (step S49), and the stop / start control processing routine is temporarily terminated.

  Here, as shown in FIGS. 9A and 9L, when the amount of operation of the brake pedal 15 by the driver decreases, the MC pressure Pmc in the master cylinder 25 is gradually reduced (9th timing t29). . At this time, the pressure of the WC pressure Pwc in each of the wheel cylinders 32a to 32d is suppressed by the operation of the linear electromagnetic valves 35a and 35b, and as a result, the braking force for the wheels FR, FL, RR, and RL is maintained. . 9 (a), (f), and (l), when the operation of the brake pedal 15 by the driver is canceled, the MC pressure Pmc in the master cylinder 25 becomes substantially “0 (zero)”. At the same time, the brake switch SW1 is turned off (tenth timing t210). At the tenth timing t210, as shown in FIG. 9 (h), engine restart control is started. Thereafter, at the eleventh timing t211, the operation of the accelerator pedal 11 by the driver is started. Then, at the twelfth timing t212 at which the engine 12 actually starts to be driven, as shown in FIGS. 9G, 9H, 9J, and 9K, the clutch shift control is started and the brake holding cancellation control is performed. Be started. Then, as shown in FIG. 9G, at the thirteenth timing t213 slightly delayed from the twelfth timing t212, the shift stage of the automatic transmission 19 is changed from the first shift stage to the second shift stage. Complete.

  Further, as shown in FIGS. 9 (i), (j), (k), and (l), the current value Isl supplied to the electromagnetic coil of the linear electromagnetic valve 35b on the right rear wheel RR side, which is the wheel on the reduced pressure steep slope side, is The WC pressure Pwc in the wheel cylinders 32b and 32c gradually decreases so as to be reduced at the first pressure reduction speed. In addition, the current value Isl supplied to the electromagnetic coil of the linear solenoid valve 35a on the left rear wheel RL side, which is a wheel on the decompression / gradient slope side, is equal to the WC pressure Pwc in the wheel cylinders 32a and 32d at the second decompression speed (<first The pressure gradually decreases so that the pressure is reduced at 1 pressure reduction speed. Then, the driving force Fd from the engine 12 transmitted to the right rear wheel RR, which is the wheel on the reduced pressure steep slope side, is the sum of the braking force applied to the right rear wheel RR and the gravity equivalent force Fg acting on the vehicle. At the fourteenth timing t214, the vehicle starts traveling forward. Note that, at the fifteenth timing t215 when the braking force on the left rear wheel RL becomes “0 (zero)”, the wheel on the reduced pressure steep slope side is changed to the left rear wheel RL and the wheel on the reduced pressure gentle slope side is moved to the right. The rear wheel is changed to RR.

Next, the calculation processing routine of the road surface inclination angle θ in step S15 will be described based on the flowchart shown in FIG.
In the road surface inclination angle θ calculation processing routine, the brake ECU 55 calculates the road surface inclination angle calculated value α using the following relational expression (Equation 2) (step S60). Note that the actual deceleration DVS and the deceleration sensor value G that are substituted into the relational expression (Equation 2) are the values obtained in steps S11 and S14.

α = arcsin (DVS-G) / g) (Formula 2)
However, g ... Standard gravity acceleration (9.8 m / s ² )
Subsequently, the brake ECU 55 updates the elapsed time T (step S61), and determines whether or not the updated elapsed time T is equal to or greater than a preset elapsed time threshold value KT2 (step S62). The elapsed time threshold value KT2 is set to a time that allows the calculated tilt angle value α to be calculated a plurality of times (for example, five times). If the determination result of step S62 is negative (T <KT2), the brake ECU 55 ends the routine for calculating the road surface inclination angle θ. On the other hand, if the determination result in step S62 is affirmative (T ≧ KT2), the brake ECU 55 resets the elapsed time T to “0 (zero)” (step S63), and until step S62 becomes a positive determination. The maximum value αmax and the minimum value αmin are extracted from the plurality of calculated tilt angle values α acquired during (step S64). Then, the brake ECU 55 determines whether or not the difference (= αmax−αmin) between the maximum value αmax and the minimum value αmin extracted in step S64 is less than a preset reference value Ksub (step S65).

  When the road surface on which the vehicle travels is a good road with less unevenness, there is little variation in the plurality of calculated tilt angles α. On the other hand, in the case of a rough road with many road surface irregularities, the variation of the plurality of calculated inclination angles α increases, and the calculated inclination angle α obtained in step S60 deviates from the actual inclination angle of the road surface. There is a possibility. Therefore, in the present embodiment, the reference value Ksub is set in advance as a reference value for determining whether or not the road surface is a rough road using the obtained plurality of calculated inclination angle values α.

  If the determination result in step S65 is affirmative ((αmax−αmin) <Ksub), the brake ECU 55 determines that the road surface is a good road and is acquired until step S62 is positive. An average value of the calculated inclination angle values α is calculated, and the average value is set as the road inclination angle θ (step S66). Therefore, in this embodiment, an inclination angle acquisition step is comprised by step S60, S66. Thereafter, the brake ECU 55 ends the routine for calculating the road surface inclination angle θ. On the other hand, when the determination result in step S65 is negative ((αmax−αmin) ≧ Ksub), the brake ECU 55 determines that the road surface is a bad road and the inclination angle θ cannot be acquired, and the road surface is inclined. The angle θ is set to the maximum inclination value θmax (for example, 30 degrees) that is the maximum value of the assumed inclination angle of the road surface (step S67). Thereafter, the brake ECU 55 ends the routine for calculating the road surface inclination angle θ.

  That is, the detection signal from the acceleration sensor SE6 includes a signal component corresponding to the reaction force received by the wheels FR, FL, RR, and RL from the road surface as well as a signal component related to actual acceleration / deceleration of the vehicle. When the road surface is a good road, the variation in reaction force received by the wheels FR, FL, RR, and RL from the road surface is small, so that each inclination angle calculated based on the acquired actual deceleration DVS and deceleration sensor value G is obtained. The calculated value α is a value close to the actual inclination angle of the road surface. Then, the tilt angle θ is set based on each calculated tilt angle value α. As a result, the braking force applied to the wheels FR, FL, RR, and RL when the vehicle is stopped is maintained at a magnitude corresponding to the actual inclination angle of the road surface or a magnitude equivalent thereto.

  On the other hand, when the road surface is a rough road, the reaction force received by the wheels FR, FL, RR, and RL from the road surface varies greatly. Therefore, each calculated based on the actual deceleration DVS and the deceleration sensor value G acquired. The variation of the calculated tilt angle α is large. Therefore, even if the inclination angle θ is set based on each calculated inclination angle α, the inclination angle θ is highly likely to deviate from the actual inclination angle of the road surface. Therefore, in this embodiment, when the road surface is a rough road, the inclination angle θ is set to the maximum inclination value θmax. As a result, the braking force applied to the wheels FR, FL, RR, RL when the vehicle is stopped is maintained with a force larger than the magnitude corresponding to the actual inclination angle of the road surface. In the present embodiment, when the tilt angle θ is set to the maximum tilt value θmax, the current value supplied to each linear electromagnetic valve 35a, 35b based on the first map shown in FIG. 3 and the above relational expression (Formula 1). Isl is set to a maximum current value (set value) Imax. Therefore, the movement of the vehicle not intended by the driver is suppressed.

Therefore, in this embodiment, the following effects can be obtained.
(1) Before the vehicle stops, transmission of the driving force Fd from the engine 12 to the rear wheels RR and RL is interrupted. Therefore, in order to maintain the stop of the vehicle after the vehicle stops, it is only necessary to hold the braking force applied to the wheels FR, FL, RR, RL. That is, the pumps 42 and 43 and the motor 41 need not be operated in order to automatically increase the braking force for the wheels FR, FL, RR, and RL on the vehicle side. Therefore, it is possible to suppress the generation of operating noise from the vehicle when the vehicle is stopped. Further, the power consumption of the vehicle can be reduced as compared with the case where the pumps 42 and 43 are operated when the vehicle is stopped to increase the braking force on the wheels FR, FL, RR, and RL.

  (2) When the brake holding control is executed, the current value Isl for holding the WC pressure (fluid pressure) Pwc in the wheel cylinders 32a to 32d increases as the inclination angle θ of the road surface on which the vehicle stops increases. Adjusted to That is, the WC pressure (fluid pressure) Pwc in the wheel cylinders 32a to 32d is held at a higher pressure and is less likely to be reduced as the road surface inclination angle θ increases. As a result, even if the operation of the brake pedal 15 by the driver is canceled in a state where the brake holding control is executed, a decrease in the braking force with respect to each wheel FR, FL, RR, RL is suppressed. Therefore, even if the road surface on which the vehicle stops is an uphill road or a downhill road, the occurrence of unintended movement of the vehicle can be suppressed. Further, for example, the power consumption of the vehicle during the brake holding control can be reduced as compared with the case where the current value Isl is set to the maximum current value Imax regardless of the inclination angle θ of the road surface.

  (3) Furthermore, in the present embodiment, it is determined whether the road surface on which the vehicle travels is a good road with relatively few irregularities or a bad road with relatively many irregularities. Then, when the road surface is a good road, the road surface inclination angle θ is calculated based on a plurality of inclination angle calculation values α acquired within a time corresponding to the elapsed time threshold value KT2. Therefore, the difference between the calculated tilt angle θ and the actual tilt angle can be minimized. As a result, a current value Isl that is extremely close to a current value corresponding to the actual inclination angle of the road surface is supplied to the electromagnetic coils of the linear electromagnetic valves 35a and 35b. Therefore, even if the driver cancels the operation of the brake pedal 15 while the vehicle is stopped on the uphill road or downhill road, the braking force for each wheel FR, FL, RR, RL is appropriate for the actual inclination angle. Since the vehicle is held by the braking force, the movement of the vehicle unintended by the driver can be suppressed.

  (4) On the other hand, when the road surface is a rough road, the variation of the plurality of calculated tilt angles α is large, so even if the tilt angle θ is calculated based on each calculated tilt angle α, the tilt angle θ Is likely to be a value deviating from the actual inclination angle. Therefore, in this embodiment, when the road surface is a rough road, the inclination angle θ is set to the maximum inclination value θmax, and the current value Isl corresponding to the maximum inclination value θmax is set in the electromagnetic coils of the linear electromagnetic valves 35a and 35b. (In this embodiment, the maximum current value Imax) is supplied. Therefore, even if the driver cancels the operation of the brake pedal 15 while the vehicle is stopped on the uphill road or downhill road, the braking force for each wheel FR, FL, RR, RL is the braking force corresponding to the actual inclination angle. Since it is held with the above braking force, the movement of the vehicle unintended by the driver can be reliably suppressed.

  (5) However, even if the road surface is a bad road, when the vehicle stops, the detection signal from the acceleration sensor SE6 corresponds to the reaction force received by the wheels FR, FL, RR, RL from the road surface. The signal component is very small. Therefore, the inclination angle θ calculated based on each inclination angle calculation value α after the vehicle stops is a value close to the actual inclination angle regardless of the degree of unevenness of the road surface. Therefore, in the present embodiment, even when it is determined that the road surface is a rough road, if the determination in step S65 is affirmative after the vehicle stops, the inclination angle θ is calculated based on each inclination angle calculation value α. Is done. Then, a current value Isl corresponding to the newly calculated inclination angle θ is supplied to the electromagnetic coils of the linear electromagnetic valves 35a and 35b. Therefore, the power consumption of the vehicle during the brake holding control is reduced as compared with the case where the current value Isl (maximum current value Imax) corresponding to the maximum tilt value θmax is continuously supplied to the electromagnetic coils of the linear solenoid valves 35a and 35b. Can be made.

  (6) In the present embodiment, the drive of the engine 12 is stopped after the clutch disengagement control and the brake holding control are executed. That is, idling is stopped. Therefore, the fuel consumption of the vehicle can be improved.

  (7) Further, after the vehicle is stopped and the brake holding control is executed, the input clutch 21 of the automatic transmission 19 in the released state is detected before detecting that the driver is willing to start the vehicle. Is returned to the engaged state. Therefore, compared with the case where the input clutch 21 is returned to the engaged state after detecting that the driver has the intention to start the vehicle, the vehicle can be quickly restarted.

  (8) If the WC pressure Pwc in each of the wheel cylinders 32a to 32d is held after the engine 12 is stopped, the MC pressure Pmc of the master cylinder 25 due to the operation stop of the booster 26 accompanying the stop of the engine 12 Following the pressure reduction, each WC pressure Pwc may also be reduced. In this case, it leads also to the fall of the braking force with respect to each wheel FR, FL, RR, RL. In this regard, in the present embodiment, after the vehicle is stopped, the engine 12 is stopped in a state where the WC pressure Pwc in each of the wheel cylinders 32a to 32d is held. Therefore, the WC pressure Pwc associated with the stop of the engine 12 can be reduced, and the braking force for the wheels FR, FL, RR, RL can be maintained.

  (9) The vehicle body speed threshold value KVS for setting the timing at which the input clutch 21 is released before the vehicle stops is set to a larger value as the actual deceleration DVS is larger. Therefore, the vehicle can be stopped in a state where the driving force Fd from the engine 12 to the wheels FR, FL, RR, and RL is reliably cut off.

  (10) When the engine 12 is restarted while the vehicle is stopped, the gear position of the automatic transmission 19 is set to a gear speed desired by the driver before the movement of the vehicle is resumed. Therefore, the vehicle can be started at an acceleration desired by the driver.

  (11) When starting the vehicle, it is checked whether or not each linear electromagnetic valve 35a, 35b operates normally. Specifically, the WC pressure Pwc in the wheel cylinder (for example, the wheel cylinder 32c) for the wheel on the decompression steep slope side is decompressed at the first decompression speed, and the wheel cylinder for the wheel on the decompression gentle slope side (for example, the wheel) The current value Isl for each linear solenoid valve 35a, 35b is individually adjusted so that the WC pressure Pwc in the cylinder 32d) is reduced at the second pressure reduction speed. Based on the magnitude of the wheel speed VW of each rear wheel RR, RL when the current value Isl for each linear solenoid valve 35a, 35b is individually adjusted, the linear solenoid valve 35a, 35b indicates an abnormality in the linear solenoid valve 35a, 35b. It is checked whether there is a solenoid valve. That is, it can be checked whether or not there is a linear solenoid valve indicating an abnormality during the brake holding cancellation control.

  (12) In the present embodiment, the wheel speed of the wheel on the reduced pressure gentle gradient side (for example, the left rear wheel RL) detected after the lapse of the predetermined time KT1 from the start of the brake holding cancellation control is the wheel on the pressure decreasing steep gradient side (for example, When the wheel speed is higher than the wheel speed of the right rear wheel RR), it is determined that the linear solenoid valve for the wheel on the decompression gentle gradient side (in this case, the linear solenoid valve 35a) is abnormal. Therefore, it is possible to determine which of the linear electromagnetic valves 35a and 35b is abnormal.

  (13) At the time of the brake holding elimination control this time, the wheel on the decompression steep slope side is the right rear wheel (first wheel) RR, and the linear solenoid valve for the wheel is the linear solenoid valve (first adjustment valve). In the case of 35b, in the next brake holding cancellation control, the wheel on the pressure reduction steep slope side is the left rear wheel (second wheel) RL, and the linear solenoid valve for the wheel is the linear solenoid valve (second adjustment). Valve) 35a. That is, the linear electromagnetic valves 35a and 35b can be checked alternately.

  (14) In this embodiment, the clutch disengagement control and the engine stop control are performed when the vehicle is stopped by the operation of the brake pedal 15 by the driver until it is determined that both the linear electromagnetic valves 35a and 35b are normal. And only brake holding control is performed among brake holding control. This is because when the clutch disengagement control and the engine stop control are performed when at least one of the linear solenoid valves 35a and 35b shows an abnormality, the operation of the brake pedal 15 by the driver is canceled to restart the vehicle on the uphill road. This is because the brake assisting force due to the engine load of the hydraulic pressure generating device 28 is insufficient when the vehicle is driven, and the vehicle may move back unnecessarily. That is, there is a possibility that the movement of the vehicle unintended by the driver may occur. Therefore, the safety of the vehicle can be maintained.

  (15) When the vehicle that stops in a state where the clutch disengagement control and the engine stop control are not executed restarts, the brake holding cancellation control is executed. At this time, it is checked whether each linear electromagnetic valve 35a, 35b operates normally. Therefore, when the vehicle is stopped in a state where it is confirmed that the linear electromagnetic valves 35a and 35b operate normally, the clutch disengagement control and the engine stop control can be executed.

  (16) However, the linear solenoid valves 35a and 35b may break down while the vehicle is traveling. In this regard, in this embodiment, when the vehicle is restarted after the vehicle is stopped with the clutch disengagement control and the engine stop control, it is checked whether or not the linear electromagnetic valves 35a and 35b operate normally. Therefore, when the linear electromagnetic valves 35a and 35b become abnormal while the vehicle is running, it is possible to restrict the clutch disengagement control and the engine stop control when the vehicle is stopped.

The embodiment may be changed to another embodiment as described below.
In the embodiment, the count threshold KCI may be a positive integer other than “3” (for example, twice).

  In the embodiment, the stop / start control process routine may be a control process in which steps S17 to S29 are omitted. In this case, the clutch disengagement control and the engine stop control are executed when the vehicle stops only after the ignition switch of the vehicle is turned on. However, if it is determined that there is a linear solenoid valve indicating an abnormality in each of the linear solenoid valves 35a and 35b by the brake holding cancellation control executed when the vehicle restarts, the clutch disconnection control is performed when the vehicle is stopped next time. It is desirable to restrict the execution of engine stop control.

  In the embodiment, when it is determined that the linear electromagnetic valves 35a and 35b are normal in the processes of steps S17 to S29, and the subsequent abnormality determination of the linear electromagnetic valves 35a and 35b is unnecessary. May reduce the WC pressure Pwc in each of the wheel cylinders 32a to 32d at the same pressure reduction speed in the brake holding cancellation control in step S45.

  In the embodiment, in the brake holding cancellation control, the current value Isl for the linear solenoid valve for the wheel on the decompression / slow gradient side is decreased at the timing of decreasing the current value Isl for the linear solenoid valve for the wheel on the decompression / slow gradient side. It may be delayed from the timing. For example, in the brake holding cancellation control, the current value Isl for the linear electromagnetic valve for the first wheel (for example, the right rear wheel RR) becomes “0 (zero)”, and then the second wheel (for example, the left rear wheel) The current value Isl for the linear electromagnetic valve for the wheel RL) may be reduced. In this case, the speed at which the current value Isl for the linear electromagnetic valves 35a and 35b is decreased may be the same speed. Even if comprised in this way, the effect equivalent to the said embodiment can be acquired.

  In the embodiment, in the brake holding elimination control, the wheel acceleration of each rear wheel RR, RL may be obtained by time differentiation of the wheel speed VW of each wheel RR, RL. Then, when the elapsed time from the start of the brake holding cancellation control exceeds a predetermined time KT1, it is determined whether or not there is a linear solenoid valve indicating an abnormality depending on the magnitude of the wheel acceleration of each of the rear wheels RR and RL. May be. This is because, when an equivalent driving force is applied to each of the rear wheels RR and RL, the wheel acceleration of a wheel with a small braking force applied is larger than the wheel acceleration of a wheel with a large braking force applied. It is to become.

  Of course, it may be determined whether or not there is a linear solenoid valve indicating an abnormality using both the wheel acceleration of each rear wheel RR and RL and the wheel speed VW of each rear wheel RR and RL. Even if comprised in these ways, the effect equivalent to the said embodiment can be acquired.

  In the embodiment, the adjustment valve disposed in each of the connection paths 33 and 34 may be a two-position electromagnetic valve. In the brake holding control, the pressure increasing valves 37a to 37d may be operated instead of the linear electromagnetic valves 35a and 35b to hold the WC pressure Pwc in the wheel cylinders 32a to 32d.

In the embodiment, the vehicle body speed threshold value KVS may be set based on the deceleration sensor value G.
The vehicle body speed threshold value KVS may be a constant value (for example, 5 km / h) regardless of the actual deceleration DVS, the deceleration sensor value G, and the like. However, it is desirable to set the vehicle body speed threshold value KVS to a value of “10 km / h” or less.

  In the embodiment, in the second clutch connection control, the shift stage of the automatic transmission 19 may be set to a shift stage (second shift stage in FIG. 9) immediately before the clutch disengagement control is executed. Further, when the shift range of the shift device 18 is the D range and the manual shift mode, the second clutch engagement control may set the shift stage of the automatic transmission 19 to the currently selected shift stage. Good. In the case of such a control configuration, the clutch shift control (step S44) may be omitted.

  In the embodiment, the engine stop control may be performed at the same timing as the brake holding control (the fifth timing t215 in FIG. 9). Even with this configuration, the engine 12 actually stops after the operation of the linear electromagnetic valves 35a and 35b is completed.

  In the embodiment, a filtering process may be performed on the calculated tilt angle value α calculated in step S60, and each process after step S61 may be performed using the calculated tilt angle value α after the filtering process.

  -In embodiment, when the information regarding the inclination angle (or gradient) of the present road surface can be acquired from the navigation apparatus etc. which are mounted in a vehicle, the electric current value supplied to the linear electromagnetic valves 35a and 35b based on the acquired information Isl may be set.

  In the embodiment, when it is determined that the road surface is a rough road and the inclination angle θ is set to the maximum inclination value θmax, the inclination angle θ may not be reacquired after the vehicle is stopped. In this case, the current value Isl corresponding to the maximum inclination value θmax is continuously supplied to the linear electromagnetic valves 35a and 35b while the vehicle is stopped.

  In the embodiment, the automatic transmission 19 is a continuously variable automatic transmission as long as the engine 12 is driven and the input clutch 21 is engaged and the vehicle can be stopped. Good.

  -In embodiment, you may embody a vehicle in what is called a hybrid vehicle and an electric vehicle which have the engine 12 and a motor as a drive source. Even in such a vehicle, it is not necessary to operate the pump in order to increase the braking force for each wheel FR, FL, RR, RL when the vehicle stops due to the operation of the brake pedal 15 by the driver.

In the embodiment, the vehicle may be a front wheel drive vehicle or a four wheel drive vehicle.
Next, the technical idea that can be grasped from the above embodiment and another embodiment will be added below.
(B) A flow resistance provided in a flow path connecting the master cylinder (25) that generates fluid pressure (Pmc) according to the brake operation by the driver and the wheel cylinder for the first wheel, and the flow resistance of the flow path A first regulating valve that operates to regulate
Adjustment for detecting an abnormality with a second adjustment valve provided in a flow path connecting the master cylinder (25) and the wheel cylinder for the second wheel and operating to adjust the flow resistance of the flow path. A valve abnormality detection method comprising:
Fluid pressure reduction suppression step for operating each of the adjustment valves (35a, 35b) so that the pressure reduction of the fluid pressure (Pwc) in each of the wheel cylinders (32a, 32b, 32c, 32d) is suppressed when the vehicle is stopped. (S18, S37),
When the vehicle starts, the control valves (35a, 35b) are operated so that the pressure reducing modes of the fluid pressures (Pwc) in the wheel cylinders (32a, 32b, 32c, 32d) are different from each other, Whether wheel speeds (VW) of the respective wheels (FR, FL, RR, RL) are respectively acquired, and whether or not there is a regulating valve indicating abnormality in each of the regulating valves (35a, 35b) based on the obtained result And an abnormality determination step (S20, S21, S22, S45, S46, S47) for determining the adjustment valve abnormality detection method.

  (B) In the abnormality determination step (S20, S21, S22, S45, S46, S47), the pressure reduction speed of the fluid pressure (Pwc) in the wheel cylinder for the first wheel and the wheel for the second wheel The adjustment valve abnormality detection method according to the technical idea (a), wherein each of the adjustment valves (35a, 35b) is operated such that the pressure reduction speed of the fluid pressure (Pwc) in the cylinder is different from each other.

  (C) In the abnormality determination step, the start timing of the pressure reduction of the fluid pressure (Pwc) in the wheel cylinder for the first wheel and the pressure reduction of the fluid pressure (Pwc) in the wheel cylinder for the second wheel The adjustment valve abnormality detection method according to the technical idea (A) or (B), wherein the adjustment valves (35a, 35b) are operated so that the start timings are different from each other.

(D) In this abnormality determination step, the fluid pressure (Pwc) in the wheel cylinder for the first wheel is 0 (Pwc) before the fluid pressure (Pwc) in the wheel cylinder for the second wheel. Each adjusting valve (35a, 35b) is actuated so that
In the next abnormality determination step, the fluid pressure (Pwc) in the wheel cylinder for the second wheel becomes 0 (zero) before the fluid pressure (Pwc) in the wheel cylinder for the first wheel. The control valve abnormality detection method according to any one of the technical ideas (A), (B), and (C), wherein the control valves (35a, 35b) are actuated as described above.

  (E) In the current abnormality determination step, when the adjustment of the current value (Isl) for the first adjustment valve is completed, the wheel speed (VW) of the second wheel is greater than that of the first wheel. The adjustment valve abnormality detection method according to the technical idea (d), wherein the second adjustment valve is detected to be abnormal when the speed is higher than a wheel speed (VW).

  (F) In the next abnormality determination step, when the adjustment of the current value (Isl) for the second adjustment valve is completed, the wheel speed (VW) of the first wheel is greater than that of the second wheel. The adjusting valve abnormality detection method according to the technical idea (d), wherein when the speed is higher than the wheel speed (VW), the first adjusting valve is detected to be abnormal.

  DESCRIPTION OF SYMBOLS 12 ... Engine as a drive source, 17, 22, 25 ... ECU as a control means, 19 ... Automatic transmission which comprises a power transmission path, 20 ... Differential gear which comprises a power transmission path, 21 ... Input clutch, 25 ... Master cylinder, 32a to 32d ... Wheel cylinder, 33, 34 ... Connection path constituting flow path, 35a, 35b ... Linear solenoid valve as adjustment valve, 36a-36d ... Path constituting flow path, 37a-37d ... Adjustment Pressure increasing valve as valve, DVS: actual deceleration of vehicle body, Fd: driving force, FR, FL, RR, RL ... wheel, KVS: vehicle body speed threshold, Pmc: MC pressure as fluid pressure, Pwc: fluid pressure WC pressure, Pwc1 ... maximum hydraulic pressure as set fluid pressure, VS ... estimated vehicle body speed, VW ... wheel speed, θ ... road slope angle.

Claims (9)

A vehicle control method executed when a braking force according to a brake operation by a vehicle driver is applied to wheels (FR, FL, RR, RL),
The vehicle has a plurality of wheels (FR, FL, RR, RL) to which a driving force (Fd) is transmitted from the drive source (12) of the vehicle, and each wheel (FR, FL, RR, RL). A plurality of individually corresponding wheel cylinders (32a, 32b, 32c, 32d),
Each flow path (33, 34, 36a, 36b) that connects each wheel cylinder (32a, 32b, 32c, 32d) and a master cylinder (25) that generates fluid pressure (Pmc) according to the brake operation by the driver. 36c, 36d) are provided with a plurality of adjusting valves (35a, 35b) for adjusting the fluid pressure (Pwc) of the wheel cylinders (32a, 32b, 32c, 32d),
Each wheel (FR, FL, RR, RL) is applied with a braking force according to the fluid pressure (Pwc) in the wheel cylinder (32a, 32b, 32c, 32d),
Before stopping the vehicle, the input clutch (21) arranged in the power transmission path (19, 20) from the drive source (12) of the vehicle to the wheels (FR, FL, RR, RL) is connected to the wheels (FR , FL, RR, RL), an efficiency reduction step (S32) for operating so that the transmission efficiency of the driving force (Fd) is reduced,
A braking force holding step (S37) for holding a braking force for the wheels (FR, FL, RR, RL) after the vehicle is stopped based on the brake operation;
When the vehicle is resumed after the braking force holding step (S37), the adjusting valves (35a, 35a, 35b, etc.) are configured such that the braking force reduction modes for the wheels (FR, FL, RR, RL) are different from each other. 35b) is operated, and the wheel speed (VW) of each wheel (FR, FL, RR, RL) is acquired, and an abnormality is detected in each adjustment valve (35a, 35b) based on the acquired result. An abnormality determination step (S45, S46, S47) for determining whether or not there is a regulating valve to be indicated
A vehicle control method characterized by comprising: The wheel (FR, FL, RR, RL) has a fluid pressure (Pwc) generated in a wheel cylinder (32a, 32b, 32c, 32d) individually corresponding to the wheel (FR, FL, RR, RL). The corresponding braking force is applied,
An inclination angle acquisition step (S60, S66) for acquiring an inclination angle (θ) of the road surface where the vehicle stops;
In the braking force holding step (S37), the greater the road surface inclination angle (θ) obtained by obtaining the fluid pressure of the wheel cylinders (32a, 32b, 32c, 32d) in the inclination angle obtaining step (S60, S66). 2. The vehicle control method according to claim 1, wherein the vehicle is held in a high pressure state. In the braking force holding step (S37), if the road surface inclination angle (θ) cannot be acquired in the inclination angle acquisition step (S60, S66), the fluid pressure of the wheel cylinders (32a, 32b, 32c, 32d) The vehicle control method according to claim 2, wherein (Pwc) is set to a preset fluid pressure (Pwc1). A drive source stop step (S38) for stopping the drive source (12) simultaneously with the braking force holding step (S37) or after the braking force holding step (S37);
In the efficiency reduction step (S32), the input clutch (21) is operated so that transmission of the driving force (Fd) to the wheels (FR, FL, RR, RL) is cut off. The vehicle control method according to any one of claims 1 to 3. After the braking force holding step (S37), the transmission efficiency of the driving force (Fd) to the wheels (FR, FL, RR, RL) of the input clutch (21) is reduced to the efficiency decreasing step (S32). The vehicle control method according to claim 4, further comprising an efficiency recovery step (S38) that operates to approach the front. A deceleration acquisition step (S11, S14) for acquiring a vehicle body deceleration (DVS, G) of the vehicle;
A threshold setting step (S30) for setting the vehicle body speed threshold (KVS) to a larger value as the acquired vehicle body deceleration (DVS, G) is larger;
The efficiency reduction step (S32) is executed when the vehicle body speed (VS) of the vehicle is equal to or less than the vehicle body speed threshold value (KVS) set in the threshold value setting step (S30). The vehicle control method according to claim 5. In this abnormality determination step, the first and second wheels (FR, FL, RR, FR) are set so that the braking force for the first wheel becomes 0 (zero) before the braking force for the second wheel. RL) individually corresponding to the first and second regulating valves (35a, 35b),
In the next abnormality determination step, the first and second adjustment valves (35a, 35b) are set so that the braking force on the second wheel becomes 0 (zero) before the braking force on the first wheel. The vehicle control method according to claim 1, wherein the vehicle control method is operated respectively. When it is determined in the abnormality determination step (S45, S46, S47) that there is a regulating valve indicating abnormality,
In the next and subsequent vehicle stop control method for a vehicle according to any one of claims 1 to 7, characterized in that to regulate the execution of the efficiency reduction step (S32). A vehicle control device for maintaining a stop of a vehicle when the vehicle is stopped by a brake operation by a driver of the vehicle,
The vehicle includes a driving source (12) and a plurality of wheels (FR, FL, RR, RL) to which driving force generated by the driving source (12) is transmitted through the power transmission path (19, 20). A plurality of wheel cylinders (32a, 32b, 32c, 32d) individually corresponding to the wheels (FR, FL, RR, RL), and an input clutch (21) provided in the power transmission path (19, 20). , A master cylinder (25) that generates a fluid pressure (Pmc) according to the brake operation by the driver, and each flow that connects the wheel cylinders (32a, 32b, 32c, 32d) and the master cylinder (25). The wheel cylinders (32a, 32b, 32c) provided in the passages (33, 34, 36a, 36b, 36c, 36d) and the flow paths (33, 34, 36a, 36b, 36c, 36d). 32d) a plurality of regulating valves (35a, 35b) for regulating the fluid pressure (Pwc), and wheel speed detecting means for detecting the wheel speed (VW) of each wheel (FR, FL, RR, RL). SE2, SE3, SE4, SE5)
Each wheel (FR, FL, RR, RL) is applied with a braking force according to the fluid pressure (Pwc) in the wheel cylinder (32a, 32b, 32c, 32d),
Control means (17, 22, 25) for controlling braking force on the input clutch (21) and the wheels (FR, FL, RR, RL);
The control means (17, 22, 25)
Wheel speed acquisition means for acquiring the wheel speed (VW) of each wheel (FR, FL, RR, RL);
Before stopping the vehicle, a transmission efficiency reduction control is performed to operate the input clutch (21) to reduce the transmission efficiency of the driving force (Fd) to the wheels (FR, FL, RR, RL),
After stopping the vehicle based on the brake operation, have rows braking force holding control to hold the braking force to the wheel (FR, FL, RR, RL ),
When the vehicle is restarted after the braking force holding control, the adjusting valves (35a, 35b) are set so that the braking force decreasing modes for the wheels (FR, FL, RR, RL) are different from each other. Execute the braking force retention cancellation control to operate each,
During the braking force holding cancellation control, wheel speeds (VW) of the wheels (FR, FL, RR, RL) are acquired, and abnormalities are found in the adjustment valves (35a, 35b) based on the acquired results. A control device for a vehicle, characterized in that it is determined whether or not there is an adjustment valve that indicates

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