JP6507755B2 - Vehicle braking system - Google Patents

Description

  The present invention relates to braking of a vehicle provided with a hydraulic braking device capable of controlling a braking force applied to the entire vehicle in coordination with a regenerative braking device, and a control device for controlling the regenerative braking device and the hydraulic pressure control device. About the system.

  Patent Document 1 describes an example of a vehicle braking system that controls a braking force applied to the entire vehicle in coordination with a regenerative braking device. This system controls the hydraulic braking device that applies a hydraulic braking force to the vehicle by adjusting the hydraulic pressure in the wheel cylinder provided for the wheel, and controls the regenerative braking device and the hydraulic braking device. And an apparatus. The hydraulic braking device has a master cylinder that generates a base hydraulic pressure in the master chamber that is a hydraulic pressure corresponding to a brake operation by the driver, and a brake actuator that adjusts a differential pressure between the master cylinder and the wheel cylinder. ing. The brake actuator is a differential pressure adjusting valve disposed in a path between the master cylinder and the wheel cylinder, and draws up the brake fluid from the master chamber and discharges the brake fluid to the path on the wheel cylinder side of the differential pressure adjusting valve. And a pump.

  In such a hydraulic braking system, the brake is applied in order to apply to the vehicle a hydraulic braking force according to the difference obtained by subtracting the regenerative braking force applied to the vehicle by the regenerative braking device from the required braking force according to the brake operation by the driver. The actuator is actuated.

  Further, in such a vehicle braking system, when the driver's brake operation lowers the vehicle body speed of the vehicle and the vehicle body speed becomes equal to or lower than the replacement control start speed, the regenerative braking force is gradually reduced according to the deceleration of the vehicle. At the same time, substitution control is performed to gradually increase the hydraulic braking force. Then, when the vehicle speed reaches the switching control end speed greater than “0 (zero)”, the switching control is ended because the regenerative braking force is “0 (zero)”. After that, the brake actuator is controlled such that the required braking force corresponding to the driver's braking operation matches the hydraulic braking force.

JP, 2006-96218, A

  When the hydraulic pressure braking force is increased to compensate for the decrease in regenerative braking force in the above-described replacement control, the brake actuator operates so that the differential pressure between the master cylinder and the wheel cylinder gradually increases. At this time, the brake fluid in the master chamber is supplied into the wheel cylinder by the pump of the brake actuator. Thus, when the brake fluid in the master chamber is reduced, the master cylinder moves in the braking direction, which is the direction for increasing the basic fluid pressure in the master cylinder, and the operating reaction force acts on the brake pedal as the brake operating member. Becomes smaller. The operation reaction force is a force acting on the brake pedal in the opposite direction to the brake operation force by the driver. Therefore, when the operation reaction force is thus reduced, the brake pedal is displaced in the braking direction even if the brake operation force by the driver is substantially constant. If the amount of displacement of the brake pedal in the braking direction is large or the displacement speed is large, the driver who is performing the braking operation may feel discomfort.

  It is an object of the present invention to provide a vehicle braking system capable of suppressing a decrease in drivability when performing substitution control that reduces the regenerative braking force and increases the hydraulic braking force in accordance with the deceleration of the vehicle at the time of brake operation. It is to provide.

  A vehicle braking system for solving the above problems includes a fluid pressure braking device that applies a fluid pressure braking force to a vehicle by adjusting a fluid pressure in a wheel cylinder provided for a wheel, and a regeneration control for the vehicle And a control device that controls a regenerative braking device that applies power and a hydraulic braking device based on a required braking force applied to the vehicle. In addition, the hydraulic braking device includes a master cylinder that generates in the master chamber a base hydraulic pressure that is a hydraulic pressure corresponding to a brake operation, and a differential pressure adjustment valve disposed in a path between the master cylinder and the wheel cylinder. And a pump for drawing up the brake fluid from the master chamber and discharging the brake fluid to a path closer to the wheel cylinder than the differential pressure adjustment valve. Further, the control device reduces the regenerative braking force applied to the vehicle by the regenerative braking device at the time of deceleration of the vehicle accompanying the brake operation, and supplies the brake fluid from the master chamber to the wheel cylinder by the operation of the pump. Implement replacement control to increase the hydraulic braking force. In the vehicle braking system based on such premise, the control device performs pre-replacement control for operating the pump before performing replacement control at the time of deceleration of the vehicle accompanying brake operation.

  When the vehicle is decelerated by the driver's brake operation, the substitution control is started. Then, when this substitution control is started, the regenerative braking force is reduced and the hydraulic braking force is increased in accordance with the deceleration of the vehicle. As described above, when the hydraulic braking force is increased, at least the pump is operated among the differential pressure adjusting valve and the pump of the hydraulic braking device, and the differential pressure between the master cylinder and the wheel cylinder is increased. Further, in the substitution control, as the regenerative braking force at the time when the substitution control is started is larger, the amount of increase in the hydraulic braking force to compensate for the decrease in the regenerative braking force becomes larger. Therefore, the differential pressure between the master cylinder and the wheel cylinder Becomes larger.

  During operation of the pump, the brake fluid in the master chamber of the master cylinder is supplied into the wheel cylinder, so the amount of brake fluid in the master chamber is reduced. In this case, since the base fluid pressure in the master chamber is reduced, in the master cylinder, the master piston is displaced in the braking direction which is the direction in which the base fluid pressure is increased. Thereby, the operation reaction force acting on the brake operation member is reduced. As a result, when the brake operating force by the driver is substantially constant, the brake operating member drivingly connected to the master piston tends to be displaced in the braking direction. The amount of displacement of the brake operating member in the braking direction is likely to increase as the amount of reduction of the brake fluid in the master chamber is large and the amount of reduction of the base hydraulic pressure is large.

  So, according to the above-mentioned composition, at the time of decelerating of the vehicle accompanying brake operation, control before substitution is carried out before implementation of substitution control. In this pre-replacement control, brake fluid is supplied from the master chamber into the wheel cylinder by operating at least the pump of the differential pressure adjusting valve and the pump of the hydraulic braking device. That is, prior to the execution of the replacement control, the amount of brake fluid in the master chamber is reduced, and the base fluid pressure, which is the fluid pressure in the master chamber, is reduced. Therefore, when the hydraulic braking force is increased by the replacement control started thereafter, the amount of reduction of the brake fluid from the master chamber is reduced compared to the case where the pre-replacement control is not performed in advance, and the base hydraulic pressure is reduced. The amount can be reduced. As a result, the decrease in the operation reaction force accompanying the execution of the substitution control is suppressed, and as a result, the amount of displacement of the brake operation member in the braking direction is less likely to be large.

Therefore, it is possible to suppress a decrease in drivability when performing replacement control.
When the brake fluid in the master chamber is reduced by the execution of the pre-replacement control, the fluid pressure in the wheel cylinder is increased.

  While the pre-replacement control is being performed, the base hydraulic pressure in the master chamber is reduced as the brake fluid in the master chamber decreases, and the hydraulic pressure in the wheel cylinder is increased. Further, since the hydraulic braking force is increased by the pressure increase of the hydraulic pressure in the wheel cylinder, the braking force applied to the entire vehicle is increased. That is, the deceleration of the vehicle tends to increase due to the implementation of the pre-replacement control. Therefore, during the execution of the pre-replacement control, if the decrease speed of the brake fluid in the master chamber, that is, the pressure increase speed of the hydraulic pressure in the wheel cylinder is large, the displacement of the brake operating member in the braking direction or the deceleration of the vehicle The increase is felt by the driver, and the driver can easily feel discomfort.

  Therefore, in the braking system of the above-described vehicle, when the pressure increase speed of the fluid pressure in the wheel cylinder during the replacement control is set as the reference pressure increase speed, the control device controls the hydraulic pressure in the wheel cylinder in the pre-replacement control. It is preferable to reduce the brake fluid in the master chamber by actuation of the hydraulic braking device so that the intensifying speed is lower than the reference intensifying speed. According to this configuration, during the execution of the pre-replacement control, the pressure increase rate of the fluid pressure in the wheel cylinder is made smaller than the pressure increase rate during the execution of the replacement control. As a result, the depressurizing speed of the base hydraulic pressure in the master chamber during the pre-replacement control can be made smaller than the depressurizing speed of the basic hydraulic pressure during the substitute control, and the braking force applied to the entire vehicle Can be reduced. Therefore, it is possible to make it difficult to displace the brake operating member in the braking direction or to make it difficult to increase the deceleration of the vehicle, and it becomes difficult to give the driver a sense of discomfort for the implementation of the pre-replacement control. Therefore, it is possible to suppress the decrease in drivability accompanying the implementation of the pre-replacement control.

  In addition, the amount of brake operation may be increased by the driver while the pre-replacement control is being performed. Thus, even when the amount of brake operation is increased, if the execution of the pre-replacement control is continued, the hydraulic pressure in the wheel cylinder is increased by both the increase in the amount of brake operation and the implementation of the pre-replacement control. The Rukoto. In this case, the increasing speed of the braking force applied to the entire vehicle may deviate from the speed intended by the driver performing the braking operation, and the drivability may be reduced.

  Therefore, in the braking system of the above-described vehicle, when the pressure increase amount of the fluid pressure in the wheel cylinder by the execution of the pre-replacement control is a boost amount, the control device performs the brake operation amount while performing the pre-replacement control. The implementation of the pre-replacement control is terminated when the brake pressure is increased, and the suppression control is performed to suppress the increase in the bulking amount by the operation of the hydraulic braking device when the increase in the brake operation amount continues. preferable. According to this configuration, when the increase in the brake operation amount is started during the execution of the pre-replacement control, the increase in the increase amount is suppressed by the execution of the suppression control during the increase in the brake operation amount. It is less likely that the speed of increase of the braking force applied to the vehicle is different from the speed intended by the driver. Therefore, it is possible to suppress a decrease in drivability when the amount of brake operation starts to increase while the pre-replacement control is being performed.

  On the other hand, the amount of brake operation may be reduced by the driver when the pre-replacement control is being performed. Thus, if the implementation of the pre-replacement control is continued even when the amount of brake operation is reduced, the driver's intention is that the actuation of the hydraulic braking device is to reduce the braking force applied to the entire vehicle. It works against the Therefore, the actual decreasing speed of the braking force applied to the entire vehicle may be smaller than the decreasing speed of the braking force correlated with the decrease mode of the brake operation amount, which may give the driver a feeling of catching.

  Therefore, in the above-described vehicle braking system, when the amount of brake operation is reduced while the pre-replacement control is being performed, the control device ends the execution of the same pre-replacement control, and thereafter the amount of brake operation decreases. It is preferable to carry out the reduction control to reduce the amount of raising by the operation of the hydraulic braking device when the above is continued. According to this configuration, when the decrease in the brake operation amount is started during the execution of the pre-replacement control, the increase amount is reduced by the execution of the decrease control during the decrease in the brake operation amount. That is, it is possible to cause the hydraulic braking device to perform an operation according to the driver's intention to reduce the braking force applied to the entire vehicle. Therefore, when the amount of brake operation starts to be reduced while the pre-replacement control is being performed, it is possible to make it difficult for the driver to get a feeling of catching and to suppress a decrease in drivability. Become.

  Further, in the vehicle braking system, when the amount of brake operation changes while performing the pre-replacement control, the control device ends the execution of the same pre-replacement control, and then the brake operation is continued. It is preferable to implement pre-replacement control when the start condition of the replacement control is not satisfied when the brake operation amount does not change under the situation.

  According to the above configuration, when the amount of brake operation is increased or decreased during execution of the pre-replacement control, the same pre-replacement control is ended. Then, the suppression control is performed when the brake operation amount is increased, and the reduction control is performed when the brake operation amount is decreased. Then, when the braking operation amount does not change while the suppression control or the reduction control is performed as described above, the pre-replacement control is performed only when the implementation condition of the replacement control does not hold. Therefore, the base fluid pressure in the master chamber can be lowered at the start of the subsequent replacement control. And, by performing the replacement control from the state where the base fluid pressure is low as described above, it is possible to reduce the amount of pressure reduction of the base fluid pressure accompanying the implementation of the replacement control. Therefore, even if the amount of brake operation is changed during the execution of the pre-replacement control, it is possible to suppress the decrease in drivability associated with the execution of the replacement control.

  In addition, after the end of the pre-replacement control, the driver may decrease the amount of brake operation. Thus, in the case of maintaining the raising amount even when the amount of brake operation is reduced, the operation of the hydraulic braking device for maintaining the raising amount is intended to reduce the braking force applied to the entire vehicle. Operation is contrary to the driver's intention. Therefore, the actual decreasing speed of the braking force applied to the entire vehicle may be smaller than the decreasing speed of the braking force correlated with the decrease mode of the brake operation amount, which may give the driver a feeling of catching.

  Therefore, when the amount of brake operation is reduced after the end of the execution of the pre-replacement control, the control device preferably performs the reduction control for reducing the amount of lifting by controlling the hydraulic braking device. According to this configuration, the bulking amount is also reduced according to the reduction of the brake operation amount. That is, it is possible to cause the hydraulic braking device to perform an operation according to the driver's intention to reduce the braking force applied to the entire vehicle. Therefore, when the driver decreases the amount of brake operation after the termination of the pre-replacement control, it is possible to make it difficult for the driver to get a feeling of catching on the driver, and it is possible to suppress a decrease in drivability.

  Preferably, in the braking system of the above-described vehicle, the start condition of the replacement control includes that the vehicle body speed of the vehicle has become less than the replacement control start speed. In addition, it is preferable that the implementation conditions of the pre-replacement control include that the vehicle body speed of the vehicle is equal to or higher than the replacement control start speed and equal to or lower than the pre-replacement control start speed that is larger than the same replacement control start speed. Then, when the execution condition of the pre-replacement control is satisfied, the control device controls the hydraulic braking device by performing the pre-replacement control to reduce the base fluid pressure in the master chamber toward the target fluid pressure. You may In this case, the pre-replacement control is terminated when the base fluid pressure in the master chamber being reduced reaches the target fluid pressure. Further, the pre-replacement control is ended when the start condition of the replacement control is satisfied, even if the base hydraulic pressure is higher than the target hydraulic pressure.

  By the way, during the execution of the pre-replacement control, if the increase speed of the fluid pressure in the wheel cylinder accompanying the implementation of the pre-replacement control is too high, the driver is likely to feel discomfort as described above. Therefore, during execution of the pre-replacement control, it is desirable to reduce the rate of decrease of the brake fluid from the master chamber, that is, the rate of decrease of the base fluid pressure, and reduce the rate of increase of the fluid pressure in the wheel cylinder.

  Assuming that the pre-replacement control start speed is a fixed value, the higher the base hydraulic pressure at the time when the pre-replacement control start condition is established, and the larger the difference between the base hydraulic pressure and the target differential pressure, the pre-replacement control The pressure reduction speed of the base fluid pressure increases during the implementation of the above, which makes it easier for the driver to feel discomfort.

  Therefore, in the above-described vehicle braking system, when the control device does not yet implement the pre-replacement control at the time of deceleration of the vehicle accompanying the brake operation, the larger the difference between the base fluid pressure and the target fluid pressure, the greater the pre-replacement control. It is preferable to increase the start speed. According to this configuration, the larger the difference between the base fluid pressure and the target fluid pressure, the larger the vehicle speed of the vehicle, and the pre-transfer control starts. As described above, by making the start timing of the pre-replacement control variable based on the above difference, even if the above difference is large, the pressure reduction rate of the base hydraulic pressure becomes large when performing the pre-replacement control. Be suppressed. Therefore, it is possible to suppress the decrease in drivability accompanying the implementation of the pre-replacement control.

  For example, when the execution condition of the pre-replacement control is satisfied, the control device controls the hydraulic braking device by performing the pre-replacement control to increase the raising amount toward the target value of the raising amount. It is also good. In this case, the larger the target value of the raising amount, the larger the amount of pressure reduction of the base hydraulic pressure accompanying the implementation of the pre-replacement control. Therefore, depending on the amount of brake operation at the start of pre-replacement control and the base hydraulic pressure, if the target value of the amount of increase is too large, the rate of decrease of the base hydraulic pressure becomes large, and for the driver performing the brake operation, The implementation of the pre-replacement control may cause discomfort.

  Therefore, in the braking system of the above-described vehicle, the control device preferably sets the target value of the raising amount based on the base hydraulic pressure and the brake operation amount when the vehicle is decelerating by the brake operation. According to this configuration, it is possible to set the target value of the raising amount to an appropriate value according to the brake operation amount and the base hydraulic pressure. Therefore, an increase in the decrease rate of the base hydraulic pressure during the execution of the pre-replacement control is suppressed, so that the drivability deterioration caused by the implementation of the pre-replacement control can be suppressed.

  If the base hydraulic pressure in the master chamber at the start of the substitution control is low, even if the brake fluid is reduced from the master chamber by the execution of the substitution control, the amount of pressure reduction of the base hydraulic pressure is small. There is almost no decline. Then, when the operation reaction force is not reduced so much, the displacement amount of the brake operation member in the braking direction is difficult to increase, and the driver does not easily feel discomfort while performing the substitution control.

  Therefore, in the braking system of the above-described vehicle, the control device preferably does not implement pre-replacement control when the base hydraulic pressure in the master chamber is less than the prescribed hydraulic pressure even when the vehicle is decelerating due to the brake operation. According to this configuration, when the base fluid pressure is less than the specified fluid pressure, it can be determined that there is almost no deterioration in drivability even if the replacement control is performed without implementing the pre-replacement control. Control is not implemented. Therefore, unnecessary implementation of the pre-replacement control can be suppressed.

  Further, when the regenerative braking force at the time of establishment of the start condition of the substitution control is small, the operation reaction force is hard to be reduced because the amount of pressure reduction of the base hydraulic pressure resulting from the execution of the substitution control is small. Then, when the operation reaction force is not reduced so much, the amount of displacement of the brake operation member in the braking direction is difficult to increase, so the driver does not easily feel discomfort while performing the substitution control.

  Therefore, in the vehicle braking system described above, the control device is configured to change the regenerative braking force applied to the vehicle by the regenerative braking device to less than the prescribed regenerative braking force even during deceleration of the vehicle due to the brake operation. It is preferable not to implement control. According to this configuration, when the regenerative braking force applied to the vehicle is less than the prescribed regenerative braking force, it is determined that the drivability hardly decreases even if the replacement control is performed without performing the pre-replacement control. Control before replacement is not implemented. Therefore, unnecessary implementation of the pre-replacement control can be suppressed.

  Here, at the initial stage of braking when the brake operation is started, the regenerative braking force applied to the vehicle by the regenerative braking device is increased. Then, if the pre-replacement control is performed while the regenerative braking force is increasing in this way, the increase speed of the braking force applied to the entire vehicle depends on the implementation of the pre-replacement control. A component based on the increase in hydraulic pressure will also be included. In this case, although the regenerative braking force can still be increased, the amount of brake operation may not be increased, and the increase of the regenerative braking force may be limited. In this case, although it is possible to suppress a decrease in drivability due to the implementation of the replacement control, there is a possibility that the recovery efficiency of the regenerative energy of the vehicle may be lowered.

  Therefore, in the above-described vehicle braking system, it is preferable that the control device does not implement the pre-replacement control when the elapsed time from the start of the brake operation is less than the specified time. According to this configuration, when the elapsed time from the start of the brake operation is less than the specified time, it can be determined that the regenerative braking force may still be able to be increased, so the pre-replacement control is not performed. ing. Thereby, it becomes possible to carry out the pre-replacement control after the regenerative braking force is increased. Therefore, it is possible to suppress the decrease in the recovery efficiency of the regenerative energy of the vehicle.

  Further, the control device may not perform the pre-replacement control when the regenerative braking force applied to the vehicle by the regenerative braking device is increased by the brake operation. Even with this configuration, the pre-replacement control can be performed after the regenerative braking force is increased. Therefore, it is possible to suppress the decrease in the recovery efficiency of the vehicle's regenerative energy accompanying the implementation of the pre-replacement control.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the outline of a hybrid vehicle provided with one Embodiment of the damping | braking system of a vehicle. BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the outline of the liquid pressure braking device which comprises the braking system of the vehicle. The block diagram which shows the outline of the master cylinder which comprises the same hydraulic pressure braking device. The graph which shows the relationship between MC pressure which is liquid pressure generated in the master room of the master cylinder of the same master cylinder, and the amount of brake operation. It is an example of a timing chart when brake operation is performed by the driver, and (a) shows transition of the body speed of vehicles, and (b) shows transition of braking power given to vehicles. It is an example of the timing chart at the time of substitution control being implemented when brake operation is performed by the driver, and (a) shows change of the body speed of vehicles, and (b) change of the amount of brake operation (C) shows the transition of the vehicle deceleration, (d) shows the transition of the MC pressure in the master room, (e) shows the transition of the control hydraulic braking force, and (f) shows the entire vehicle It shows the transition of the applied braking force and regenerative braking force. When a brake operation is performed by the driver, it is an example of a timing chart at the time of control before substitution and substitution control being performed, and (a) shows transition of the body speed of vehicles, and (b) shows (C) shows the transition of the deceleration of the vehicle, (d) shows the transition of the MC pressure in the master chamber, (e) shows the transition of the control hydraulic braking force, (f Shows the transition of the braking force and the regenerative braking force applied to the entire vehicle. A processing routine that is executed by the control device that constitutes the braking system of the same vehicle, and when start control before substitution, holding control, decrease control and substitution control are not performed, the start timing of before substitution control and substitution control is determined The flowchart explaining the processing routine for doing. The flowchart which is a processing routine which the same control device performs, and when control before substitution is carried out, a processing routine for determining start timing of maintenance control, reduction control, and substitution control. The flowchart which is a processing routine which the same control device performs, and when retention control is carried out, it is a processing routine for determining the start timing of control before substitution, reduction control, and substitution control. The flowchart which is a processing routine which the same control device performs, and when reduction control is carried out, the processing routine for determining the start timing of control before substitution, maintenance control, and substitution control. The flowchart which is a processing routine which the same control device performs, and when substitution control is carried out, it is a processing routine for determining the start timing of control before substitution, holding control, and reduction control. It is an example of a timing chart at the time of control to which control carried out in order of control before substitution, holding control, and control before substitution is shifted, and (a) shows transition of demand braking power, (b) transition of the amount of raising Indicates

  Hereinafter, an embodiment in which a braking system of a vehicle is embodied will be described according to FIGS. In the following description of the present specification, the traveling direction (forward direction) of the vehicle will be described as the front (vehicle front).

  FIG. 1 shows a hybrid vehicle provided with the vehicle braking system of the present embodiment. As shown in FIG. 1, in a hybrid vehicle, a two-motor hybrid system 10 and a hydraulic braking device 20 for applying a braking force (hydraulic braking force) to all the wheels FL, FR, RL, RR , And the control device 100 are provided. The hydraulic braking device 20 and the control device 100 constitute an example of a "vehicle braking system".

  The hybrid system 10 includes an engine 11 operated by supply of fuel such as gasoline. A first motor 13 and a second motor 14 are connected to a crankshaft 11 a of the engine 11 through a power transmission mechanism 12 having a planetary gear mechanism or the like. The power transmission mechanism 12 divides and transmits the power from the engine 11 to the first motor 13 and the front wheels FL and FR which are driving wheels. Further, at the time of driving of the second motor 14, the power transmission mechanism 12 transmits the power from the second motor 14 to the front wheels FL, FR.

  The first motor 13 generates electric power by the power transmitted through the power transmission mechanism 12. The electric power generated by the first motor 13 is supplied to the battery 16 via the inverter 15 and stored.

  The second motor 14 functions as a drive source of the vehicle when the driver operates the accelerator pedal 18. At this time, power is supplied from the battery 16 to the second motor 14 via the inverter 15. Then, the power generated by the second motor 14 is transmitted to the front wheels FL, FR via the power transmission mechanism 12 and the differential 17. In the vicinity of the accelerator pedal 18, an accelerator opening degree sensor SE1 is provided which outputs to the control device 100 a signal according to the accelerator operation amount which is the operation amount of the accelerator pedal 18.

  On the other hand, the power accompanying the rotation of the front wheels FL and FR is transmitted to the second motor 14 through the differential 17 and the power transmission mechanism 12 when the driver operates the brake pedal 21 as the brake operation member. At this time, the second motor 14 functions as a generator, and the electric power generated by the second motor 14 is supplied to the battery 16 via the inverter 15 and stored. Then, the second motor 14 generating electric power in this way applies regenerative braking force according to the amount of electric power generated by the second motor 14 to the vehicle. Therefore, the second motor 14 constitutes an example of the “regenerative braking device”.

Next, the hydraulic braking device 20 will be described.
The hydraulic braking device 20 includes a hydraulic pressure supply device 50 to which the brake pedal 21 is drivingly connected, and a brake actuator 30 capable of automatically adjusting the hydraulic braking force to the wheels FL, FR, RL, and RR. Further, the hydraulic pressure braking device 20 is provided with a brake operation amount sensor SE2 that outputs a signal corresponding to the brake operation amount, which is the operation amount of the brake pedal 21, to the control device 100.

  As shown in FIG. 2, the brake actuator 30 is provided with two hydraulic circuits 311 and 312. The first hydraulic circuit 311 is connected to the wheel cylinder 22a for the left front wheel and the wheel cylinder 22b for the right front wheel, and the second hydraulic circuit 312 is connected to the wheel cylinder 22c for the left rear wheel. And a wheel cylinder 22d for the right rear wheel are connected. Then, when the brake fluid flows from the fluid pressure supply device 50 into the first and second hydraulic circuits 311 and 312, the brake fluid flows into the wheel cylinders 22a to 22d, and the fluid in the wheel cylinders 22a to 22d The wheel cylinder pressure (hereinafter also referred to as “WC pressure”), which is the pressure, is increased. As a result, hydraulic braking force corresponding to the WC pressure is applied to the wheels FL, FR, RL, RR.

  In a path connecting the master cylinder 51 of the hydraulic pressure supply device 50 and the wheel cylinders 22a to 22d, differential pressure adjusting valves 321 and 322, which are linear solenoid valves, are provided. In the first hydraulic circuit 311, a path 33a for the left front wheel and a path 33b for the right front wheel are provided closer to the wheel cylinders 22a and 22b than the differential pressure adjustment valve 321, and a second hydraulic circuit A path 33c for the left rear wheel and a path 33d for the right rear wheel are provided closer to the wheel cylinders 22c and 22d than the differential pressure adjustment valve 322 at 312. Then, in the paths 33a to 33d, pressure increase valves 34a, 34b, 34c, 34d, which are normally open solenoid valves that operate when restricting the pressure increase of the WC pressure in the wheel cylinders 22a to 22d, and the WC pressure The pressure reducing valves 35a, 35b, 35c and 35d, which are normally closed solenoid valves that operate when the pressure in the valve is reduced, are provided.

  In the first and second hydraulic circuits 311 and 312, reservoirs 361 and 362 for temporarily storing the brake fluid that has flowed out from the wheel cylinders 22a to 22d through the pressure reducing valves 35a to 35d, and the pump motor 37 The supply pumps 381 and 382, which operate based on the rotation, are connected. The reservoirs 361 and 362 are connected to the supply pumps 381 and 382 through the suction flow channels 391 and 392, and connected to the flow passage on the master cylinder 51 side of the differential pressure control valves 321 and 322 through the master flow channels 401 and 402. It is done. The supply pumps 381 and 382 are connected to connection portions 421 and 422 between the differential pressure control valves 321 and 322 and the pressure increasing valves 34a to 34d through the supply flow paths 411 and 412, respectively. Then, when the pump motor 37 is driven, the supply pumps 381, 382 draw the brake fluid from the reservoirs 361, 362 and the master cylinder 51 through the suction flow paths 391, 392 and the master side flow paths 401, 402, The brake fluid is discharged into the supply channels 411 and 412. That is, by the differential pressure adjusting valves 321 and 322 and the supply pumps 381 and 382 operating, a differential pressure is generated between the master cylinder 51 and the wheel cylinders 22a to 22d, and the fluid pressure braking force according to the differential pressure. Is given to the vehicle.

  The hydraulic pressure supply device 50 includes, in addition to the master cylinder 51, a booster device 52 for assisting the brake operating force which is the operating force of the brake pedal 21 by the driver, and an atmospheric pressure reservoir 53 in which the brake fluid is stored. . Here, as the booster device 52, a device connected to an intake manifold that generates negative pressure when the engine 11 is in operation is employed. In this booster device 52, the pressure difference between the negative pressure generated in the intake manifold and the atmospheric pressure is used to assist the driver's braking operation force.

  As shown in FIG. 3, in a bottomed cylindrical housing 60 constituting the master cylinder 51, two master pistons 611 and 612 arranged in the lateral direction in the drawing are provided. Each of the master pistons 611 and 612 is slidable along the inner peripheral wall of the cylindrical portion 60 a of the housing 60 in the axial direction (left and right direction in FIG. 3). That is, the master pistons 611 and 612 slide in the braking direction which is the left direction in the figure by the driver's brake operation.

  Also, in the first master chamber 621 formed between the bottom wall 60 b of the housing 60 and the first master piston 611, in the non-braking direction (right direction in the drawing) which is the opposite direction of the braking direction A first spring 631 is provided to apply the biasing force of the first master piston 611. In addition, in a second master chamber 622 formed between the first master piston 611 and the second master piston 612, a second master chamber 612 is biased in a non-braking direction. A spring 632 is provided.

  Then, when the brake operating force acting on the first and second master pistons 611 and 612 becomes large, the first and second master pistons 611 and 612 receive the biasing force from the first and second springs 631 and 632, respectively. By sliding in the braking direction, the volumes of the first and second master chambers 621 and 622 become narrow. On the other hand, when the brake operation force acting on the first and second master pistons 611 and 612 decreases, the biasing forces from the first and second springs 631 and 632 cause the first and second master pistons 611 and 612 to move. Sliding in the non-braking direction, the volumes of the first and second master chambers 621 and 622 become large.

  Further, the inside of the first master chamber 621 communicates with the first hydraulic circuit 311 of the brake actuator 30, and also communicates with the atmospheric pressure reservoir 53 through the first communication passage 651. Further, the inside of the second master chamber 622 communicates with the second hydraulic circuit 312 of the brake actuator 30 and also communicates with the atmospheric pressure reservoir 53 through the second communication passage 652.

  The communication between the first and second master chambers 621 and 622 and the first and second hydraulic circuits 311 and 312 is maintained regardless of whether the brake operation amount BPInput is large or small. On the other hand, the communication between the first and second master chambers 621 and 622 and the atmospheric pressure reservoir 53 is maintained when the brake operation amount BPInput is less than the ineffective operation amount BPInputTh, while the brake operation amount BPInput is ineffective. When it is equal to or greater than the operation amount BPInputTh, it is shut off.

  Here, a master cylinder pressure (hereinafter also referred to as “MC pressure”) Pmc, which is a hydraulic pressure in the first and second master chambers 621 and 622, is a pressure in the atmospheric pressure reservoir 53 (for example, atmospheric pressure). Relative pressure with respect to The MC pressure Pmc corresponds to the "base fluid pressure". Then, as shown in FIG. 4, when the brake operation amount BPInput is less than the ineffective operation amount BPInputTh, the MC pressure Pmc in the first and second master chambers 621 and 622 is the first and second master chambers 621 and 622. , 622 are in communication with the atmospheric pressure reservoir 53, and thus become “0 (zero)”. As described above, when the MC pressure Pmc is “0 (zero)”, the brake fluid does not flow out of the first and second master chambers 621 and 622 to the first and second hydraulic circuits 311 and 312.

  On the other hand, when the brake operation amount BPInput is equal to or more than the ineffective operation amount BPInputTh, the MC pressure Pmc is a brake because the communication between the first and second master chambers 621 and 622 and the atmospheric pressure reservoir 53 is blocked. As the operation amount BPInput increases, it gradually increases. That is, as the brake operation amount BPInput increases, the amount of brake fluid flowing out of the first and second master chambers 621 and 622 to the first and second hydraulic circuits 311 and 312 increases, and the wheel cylinder The WC pressure in 22a-22d becomes high. As a result, the vehicle is provided with a base hydraulic pressure braking force BPB which is a hydraulic pressure braking force corresponding to the MC pressure Pmc which is a base hydraulic pressure.

  Incidentally, the brake operation amount BPInput is correlated to a certain extent with the required braking force BPT, which is the braking force required by the driver for the vehicle. Then, when the brake operation amount BPInput is less than the ineffective operation amount BPInputTh, the braking force (also referred to as “control braking force”) controlled by the control device 100 is applied to the vehicle. The control braking force is generated by the regenerative braking force BPR applied to the vehicle by the second motor 14 as a regenerative braking device, and between the master cylinder 51 and the wheel cylinders 22a to 22d generated by the operation of the brake actuator 30. The control hydraulic pressure braking force BPP which is a hydraulic pressure braking force corresponding to the differential pressure is included.

Next, with reference to a timing chart shown in FIG. 5, an example of applying a braking force to the vehicle by the driver's brake operation will be described.
As shown in FIGS. 5A and 5B, when the brake operation is started at a first timing t11, the deceleration of the vehicle is started. At this time, the brake operation amount BPInput gradually increases from the state of “0 (zero)”. Therefore, at a stage where the brake operation amount BPInput is small, the required braking force BPT can be covered only by the regenerative braking force BPR. After that, from the second timing t12 onward, the increasing speed of the regenerative braking force BPR becomes smaller than the increasing speed of the required braking force BPT, and a deviation occurs between the required braking force BPT and the regenerative braking force BPR. It will be.

  Therefore, at the second timing t12, the differential pressure between the inside of the master cylinder 51 and the inside of the wheel cylinders 22a to 22d is increased by the operation of the differential pressure adjusting valves 321 and 322 and the supply pumps 381 and 382. The differential pressure at this time has a magnitude corresponding to the difference between the required braking force BPT and the regenerative braking force BPR. As a result, between the second timing t12 and the fourth timing t14 when the regenerative braking force BPR reaches the required braking force BPT corresponding to the ineffective operation amount BPInputTh, the differential pressure adjusting valves 321 and 322 and the supply pump 381, A controlled hydraulic braking force BPP based on the operation of 382 is applied to the vehicle.

  When the third timing t13 elapses, the brake operation amount BPInput exceeds the ineffective operation amount BPInputTh. Therefore, the MC pressure Pmc in the master chamber 621 or 622 is a difference obtained by subtracting the ineffective operation amount BPInputTh from the brake operation amount BPInput. The pressure is increased according to a certain effective operation amount. Then, the WC pressure in each of the wheel cylinders 22a to 22d is increased by an amount corresponding to the increase in the MC pressure Pmc. That is, after the third timing t13, the base hydraulic pressure braking force BPB based on the pressure increase of the MC pressure Pmc is also applied to the vehicle.

Next, the control device 100 will be described with reference to FIG.
As shown in FIG. 1, in addition to the accelerator opening sensor SE1 and the brake operation amount sensor SE2, the control device 100 includes a vehicle speed sensor SE4 for detecting a vehicle body speed VS of the vehicle, and first and second master cylinders 51. A hydraulic pressure detection sensor SE5 (see FIG. 2) for detecting the MC pressure Pmc in the two master chambers 621 and 622 is electrically connected. Then, control device 100 performs vehicle control in an integrated manner based on detection signals from various detection systems such as various sensors SE1, SE2, SE4, SE5.

  The control device 100 controls the power management computer 101, the engine control unit 102 for controlling the engine 11, the motor control unit 103 for controlling the first and second motors 13 and 14, and the hydraulic braking device 20. And a brake control unit 104.

  When the driver performs an accelerator operation, the power management computer 101 calculates the required power required for the engine 11 and the required power required for the second motor 14 based on the traveling state of the vehicle. Then, the power management computer 101 individually transmits a control command based on the calculated required power to the engine control unit 102 and the motor control unit 103.

  Further, the power management computer 101 calculates the regenerative braking force that can be applied to the front wheels FL, FR at that time based on the storage amount of the battery 16 at that time, the wheel speed of the front wheels FL, FR and the like. Then, the power management computer 101 transmits the calculated regenerative braking force to the brake control unit 104 at that time.

  The power management computer 101 receives information on the instruction value of the regenerative braking force calculated by the brake control unit 104 at the time of deceleration of the vehicle accompanying the brake operation by the driver. Then, the power management computer 101 transmits the received information to the motor control unit 103. Further, the power management computer 101 receives, from the motor control unit 103, information on the regenerative braking force BPR that the second motor 14 is currently applying to the vehicle, and transmits the information to the brake control unit 104.

  The motor control unit 103 receives, from the power management computer 101, information on an instruction value of the regenerative braking force at the time of deceleration of the vehicle accompanying the brake operation by the driver. Then, the motor control unit 103 causes the second motor 14 to generate power so that regenerative braking force equivalent to the instruction value of regenerative braking force based on the received information is applied to the front wheels FL, FR. Further, the motor control unit 103 calculates the regenerative braking force BPR applied to the vehicle by the second motor 14 based on the amount of electric power generated by the second motor 14 and the like, and powers information on the regenerative braking force BPR. It transmits to the management computer 101.

  The brake control unit 104 calculates the brake operation amount BPInput based on the signal from the brake operation amount sensor SE2 when the driver is performing the brake operation, and the MC pressure based on the signal from the hydraulic pressure detection sensor SE5. Calculate Pmc. Further, the brake control unit 104 calculates a required braking force BPT that the driver requests the vehicle based on the calculated brake operation amount BPInput and the MC pressure Pmc. Then, the brake control unit 104 calculates an instruction value of the regenerative braking force based on the calculated required braking force BPT or the regenerative braking force that can be applied to the front wheels FL, FR at that time, etc. Send to 101

  The brake control unit 104 calculates the current base hydraulic braking force BPB based on the calculated MC pressure Pmc. When the brake control unit 104 determines that the required braking force BPT can be obtained by the regenerative braking force BPR and the basic fluid pressure braking force BPB, the brake control unit 104 does not operate the brake actuator 30. That is, the brake control unit 104 does not apply the control hydraulic braking force BPP from the hydraulic braking device 20 to the vehicle. On the other hand, the brake control unit 104 applies the control hydraulic braking force BPP to the vehicle from the hydraulic braking device 20 when the sum of the regenerative braking force BPR and the basic hydraulic pressure braking force BPB is less than the required braking force BPT. By managing the regenerative braking force BPR, the control hydraulic braking force BPP, and the base hydraulic braking force BPB as described above, the recovery efficiency of the regenerative energy of the vehicle can be enhanced.

  By the way, as shown in FIGS. 6 (a), (b), (c), (d), (e) and (f), when the vehicle is decelerated in response to the driver's brake operation, the vehicle At the time of low speed traveling before being stopped, substitution control may be performed. In this substitution control, control is performed to decrease the regenerative braking force BPR applied to the vehicle toward “0 (zero)” and to increase the control hydraulic braking force BPP so as to compensate for the decrease in the regenerative braking force BPR. It is.

As described above, the implementation conditions of the substitution control performed when the vehicle travels at low speed includes that all of the following two conditions (conditions 1-1) and (conditions 1-2) are satisfied.
(Condition 1-1) The vehicle is decelerating in response to a brake operation by the driver, and the regenerative braking force BPR is applied to the vehicle.
(Condition 1-2) The vehicle speed VS of the vehicle is less than the switching control start speed VSTh1.

  That is, as shown in FIGS. 6A to 6F, at the first timing t21 during deceleration of the vehicle accompanying the brake operation, the vehicle speed VS is higher than the switching control start speed VSTh1 at the first timing t21. In order to shift to a state below the switching control start speed VSTh1, switching control is started. In the example shown in FIG. 6, the brake actuator 30 has already been actuated to apply the control hydraulic braking force BPP to the vehicle before the start of the substitution control. Therefore, in the brake actuator 30, the opening degree of the differential pressure adjustment valves 321 and 322 is gradually reduced while the operation of the supply pumps 381 and 382 is continued. The change speed of the opening degree of the differential pressure adjustment valve 321, 322 at this time is correlated with the decrease speed of the regenerative braking force BPR. As a result, the control hydraulic braking force BPP is increased at a speed that correlates with the decrease speed of the regenerative braking force BPR.

  Then, at a second timing t22 when the vehicle body speed VS of the vehicle becomes equal to or less than the switching control end speed VSTh2, the regenerative braking force BPR becomes "0 (zero)", and the switching control is ended. Then, in the brake actuator 30, in order to hold the control hydraulic pressure braking force BPP applied to the vehicle, the opening degree of the differential pressure adjustment valve 321, 322 is held. Then, the vehicle is stopped at the third timing t23 when the regenerative braking force BPR is not applied to the vehicle as described above.

  In the hydraulic braking device 20, when the control hydraulic braking force BPP is increased, the brake fluid from the inside of the master chambers 621, 622 of the master cylinder 51 is operated by operating the supply pumps 381, 382 and the differential pressure adjusting valves 321, 322. The fluid is pumped by the feed pumps 381, 382, and at least a part of the brake fluid is supplied into the wheel cylinders 22a to 22d. As a result, during the replacement control, although the control hydraulic braking force BPP is increased by the increase of the WC pressure, the brake fluid in the master chambers 621 and 622 is decreased, and the inside of the master chambers 621 and 622 is reduced. The MC pressure Pmc is reduced. When the MC pressure Pmc is thus reduced as described above, the operation reaction force to the brake pedal 21 operated by the driver decreases as the amount of pressure reduction increases. At this time, even if the brake operating force by the driver is constant, the brake pedal 21 is displaced in the braking direction regardless of the driver's intention.

  Here, in order to increase the recovery efficiency of the regenerative energy of the vehicle, the switching control start speed VSTh1 is set to a value as small as possible, and the reduction speed of the regenerative braking force BPR during the switching control is as large as possible. It is desirable to do. However, when the decrease rate of the regenerative braking force BPR is increased as described above, the pressure decrease rate of the MC pressure Pmc during the execution of the replacement control is increased. Therefore, the decrease speed of the operation reaction force to the brake pedal 21 is increased, and the displacement speed of the brake pedal 21 in the braking direction is increased (see FIG. 6B). As a result, even if the brake operating force by the driver is constant, the brake pedal 21 is rapidly displaced in the braking direction, which gives the driver who operates the brake pedal 21 a sense of discomfort.

  Further, during the execution of the substitution control, the brake actuator 30 is operated such that the control hydraulic braking force BPP increases in conjunction with the decrease of the regenerative braking force BPR. However, due to the response delay of the brake actuator 30, the actual increase speed of the control hydraulic braking force BPP becomes smaller than the increase speed of the control hydraulic braking force BPP required by the control device 100. Therefore, as shown in FIG. 6C, the deceleration DVS of the vehicle may be reduced even if the required braking force BPT requested by the driver is constant. Such an event appears notably by increasing the decrease rate of the regenerative braking force BPR during the execution of the replacement control.

  Therefore, as shown in FIGS. 7 (a), (b), (c), (d), (e) and (f), in the vehicle braking system of the present embodiment, the drivability associated with the execution of the replacement control. In order to suppress the decrease of the vehicle speed, the pre-replacement control is performed before the implementation of the replacement control at the time of deceleration of the vehicle accompanying the brake operation by the driver. The pre-replacement control reduces the brake fluid from the master chambers 621 and 622 in order to reduce the MC pressure Pmc in the master chambers 621 and 622 toward the target hydraulic pressure PmcTr, and the WC in the wheel cylinders 22a to 22d. It is control to raise pressure. Further, at the time of implementation of the pre-replacement control, the regenerative braking force BPR is not reduced in conjunction with the increase of the control hydraulic braking force BPP resulting from the pressure increase of the WC pressure.

  Even if the brake fluid is reduced from the inside of the master chambers 621 and 622 and the MC pressure Pmc is reduced, static friction is applied to sliding members such as the master pistons 611 and 612. Therefore, when the amount of pressure reduction of the MC pressure Pmc is not very large, the sliding of the sliding member is restricted by the static friction force, and the master pistons 611 and 612 are hardly displaced in the braking direction. As a result, the brake pedal 21 drivingly connected to the master pistons 611 and 612 is hardly displaced in the braking direction, and it is difficult for the driver who is performing the braking operation to feel discomfort. Therefore, even if the target hydraulic pressure PmcTr is reduced from the target hydraulic pressure PmcTr by the execution of the replacement control, the target hydraulic pressure PmcTr is set to a size that allows the reduction amount and the reduction speed of the operation reaction force to fall within the allowable range. It is set.

  Then, when the start condition of the pre-replacement control is satisfied at a first timing t31 while the vehicle is decelerating along with the brake operation, the pre-replacement control is started. In the example shown in FIG. 7, the brake actuator 30 has already been actuated to apply the control hydraulic braking force BPP to the vehicle before the start of the pre-replacement control. Therefore, in the brake actuator 30, the operation of the supply pumps 381 and 382 is continued, and the opening degree of the differential pressure adjustment valves 321 and 322 is gradually reduced. Then, the differential pressure between the master cylinder 51 and the wheel cylinders 22a to 22d gradually increases, and the WC pressure in the wheel cylinders 22a to 22d is gradually increased. The amount of pressure increase of the WC pressure accompanying the implementation of such pre-replacement control is also referred to as "bulking amount RS". That is, the pre-replacement control can also be referred to as control for increasing the raising amount RS to the target value RSTr of the raising amount. The target value RSTr of the raising amount is a value correlated with the difference obtained by subtracting the target hydraulic pressure PmcTr from the MC pressure Pmc at the start of the pre-replacement control. That is, when the raising amount RS is increased to the target value RSTr of the raising amount by the execution of the control before replacement, the MC pressure Pmc is reduced to the target hydraulic pressure PmcTr.

  During the execution of the pre-replacement control, as shown in FIGS. 7 (e) and 7 (f), although the control hydraulic braking force BPP is increased, the regenerative braking force BPR is different from that during the replacement control. Not reduced. Therefore, as shown in FIGS. 7 (c) and 7 (f), although the required braking force BPT is not changed, the braking force BPA applied to the entire vehicle is large by the execution of the pre-replacement control. And the deceleration DVS of the vehicle also increases. At this time, when the increase speed of the deceleration DVS of the vehicle is small, the driver does not easily feel the increase of the deceleration DVS, but when the increase speed of the deceleration DVS is large, the driver feels the increase of the deceleration DVS Can.

  Therefore, in the vehicle braking system of the present embodiment, the increase speed of the control hydraulic braking force BPP is reduced so that the driver does not feel much the increase in the deceleration DVS of the vehicle accompanying the implementation of the pre-replacement control. Specifically, the change speed of the opening degree of the differential pressure adjustment valve 321, 322 during the execution of the pre-replacement control is smaller than the change speed of the opening degree of the differential pressure control valve 321, 322 during the execution of the substitution control. Thus, assuming that the pressure reduction rate of the WC pressure in the wheel cylinders 22a to 22d during replacement control is a reference reduction rate, the reduction rate of the WC pressure in the wheel cylinders 22a to 22d during replacement control is: It becomes smaller than the standard pressure reduction rate. That is, the WC pressure in the wheel cylinders 22a to 22d is slowly increased, and the control hydraulic braking force BPP is increased at a small speed.

  Then, at a second timing t32 while the pre-replacement control is being performed, the vehicle body speed VS of the vehicle becomes less than the replacement control start speed VSTh1. That is, the execution condition of the pre-replacement control is not satisfied, and the start condition of the substitution control is satisfied. Therefore, at the second timing t32, the pre-replacement control is ended and the replacement control is started.

  Then, unlike the time of implementation of the pre-replacement control, the regenerative braking force BPR is decreased, and the control hydraulic braking force BPP is increased to compensate for the decrease in the regenerative braking force BPR. Therefore, as indicated by a broken line in FIG. 7F, even if the control hydraulic braking force BPP is increased as described above, the braking force BPA applied to the entire vehicle is less likely to be increased than when the pre-replacement control is performed. .

  Thus, when implementing substitution control after implementation of control before substitution, the opening degree of the differential pressure adjustment valve 321, 322 is made smaller than the opening degree at the time of completion of the control before substitution. Therefore, in the example shown in FIG. 7, during the execution of the replacement control, the raising amount RS at the end time of the pre-replacement control is maintained.

  Further, as shown in FIG. 7 (d), since the pre-replacement control was performed before the implementation of the replacement control, the amount of liquid in the master chambers 621 and 622 is reduced, and the start point of the replacement control The MC pressure Pmc in the master chambers 621 and 622 in FIG. In the example shown in FIG. 7, the MC pressure Pmc is equal to the target fluid pressure PmcTr. Therefore, compared with the case where the pre-replacement control is not performed, the amount of pressure reduction of the MC pressure Pmc accompanying the implementation of the replacement control becomes smaller. As a result, during the execution of the substitution control, the operation reaction force to the brake pedal 21 is less likely to decrease, and the displacement amount of the brake pedal 21 in the braking direction decreases. Then, such switching control is ended at the third timing t33 when the vehicle body speed VS of the vehicle reaches the switching control end speed VSTh2.

Note that the execution conditions of the pre-replacement control are that the following four conditions (conditions 2-1), (conditions 2-2), (conditions 2-3) and (conditions 2-4) are all satisfied. Contains.
(Condition 2-1) The brake pedal 21 is operated, and the MC pressure Pmc in the master chambers 621 and 622 is equal to or higher than the specified hydraulic pressure PmcThL.
(Condition 2-2) The regenerative braking force BPR applied to the vehicle is equal to or greater than a prescribed regenerative braking force BPRTh.
(Condition 2-3) The vehicle body speed VS of the vehicle is equal to or higher than the switching control start speed VSTh1 and lower than the control start speed VSTh3 before switching. However, the pre-replacement control start speed VSTh3 is a value larger than the replacement control start speed VSTh1.
(Condition 2-4) The operating state of the brake pedal 21 is in the holding state.

  If the MC pressure Pmc is less than the specified hydraulic pressure PmcThL, it can be determined that the amount of brake fluid in the master chambers 621 and 622 is relatively large. Therefore, in such a case, even if the replacement control is performed without performing the pre-replacement control, the MC pressure Pmc is not significantly reduced. As a result, the operation reaction force to the brake pedal 21 does not easily decrease, and the drivability does not decrease so much even if the replacement control is performed. Therefore, it can be determined that the implementation of the pre-replacement control is unnecessary. The prescribed hydraulic pressure PmcThL may be set to any value as long as it is a value near the above target hydraulic pressure PmcTr. For example, it may be a value equal to the target hydraulic pressure PmcTr or slightly smaller than the target hydraulic pressure PmcTr. May be a large value.

  Further, when the regenerative braking force BPR applied to the vehicle is less than the specified regenerative braking force BPRTh, it can be determined that the regenerative braking force BPR is small. Since the replacement control is control for replacing the regenerative braking force BPR applied to the vehicle with the control hydraulic braking force BPP, the MC pressure Pmc is not reduced so much even if replacement control is performed in a state where the regenerative braking force BPR is small. . As a result, the operation reaction force to the brake pedal 21 does not easily decrease, and the brake pedal 21 does not easily displace in the braking direction. Therefore, it can be determined that the implementation of the pre-replacement control is unnecessary.

  By the way, in order to reduce the increase speed DBPR of the control hydraulic braking force at the time of execution of the pre-replacement control, the pre-replacement control start speed VSTh3 at the start time of the pre-replacement control and the target value of the pre-replacement control It is desirable to make the target value RSTr of the volume increase amount variable based on the MC pressure Pmc and the brake operation amount BPInput at that time. Then, by setting the target value RSTr of the raising amount in this way based on the MC pressure Pmc and the brake operation amount BPInput at that time, the target hydraulic pressure PmcTr correlating with the target value RSTr of the raising amount is also It can be varied based on the MC pressure Pmc and the brake operation amount BPInput.

  For example, the target value RSTr of the raising amount is a value corresponding to the MC pressure Pmc and the brake operation amount BPInput at that time by using a map showing the relationship between the MC pressure Pmc and the brake operation amount BPInput and the target value candidate value. It can be set to That is, when the brake operation amount BPInput is constant, the target value RSTr of the raising amount is set to a smaller value as the MC pressure Pmc is lower. Further, when the MC pressure Pmc is constant, the target value RSTr of the raising amount is set to a smaller value as the brake operation amount BPInput is smaller. Then, the target hydraulic pressure PmcTr is set to a value corresponding to the target value RSTr of the amount of increase to be set as described above.

The pre-replacement control start speed VSTh3 is set to a larger value as the difference between the specified value of the target fluid pressure PmcTr and the MC pressure Pmc at that time is larger.
In addition, when the brake operation amount BPInput is changed by the driver, it is desirable not to implement the pre-replacement control. For example, it is assumed that pre-replacement control is performed when the brake operation amount BPInput is increased by the driver. In this case, the braking force BPA applied to the entire vehicle is increased by both the increase of the brake operation amount BPInput and the implementation of the pre-replacement control. That is, not only the regenerative braking force BPR and the base hydraulic pressure braking force BPB are increased by the increase of the brake operation amount BPInput, but the control hydraulic pressure braking force BPP is also increased by the execution of the pre-replacement control. As a result, the increasing speed of the braking force BPA applied to the entire vehicle may deviate from the speed intended by the driver performing the braking operation, and drivability may be reduced.

  On the contrary, it is assumed that pre-replacement control is performed when the brake operation amount BPInput is decreased by the driver. The operation of the brake actuator 30 in this case is an operation contrary to the driver's intention to reduce the braking force BPA applied to the entire vehicle. That is, although the regenerative braking force BPR and the basic fluid pressure braking force BPB are decreased due to the decrease of the brake operation amount BPInput, the control fluid pressure braking force BPP is increased by the execution of the pre-replacement control. Therefore, the actual decreasing speed of the braking force BPA applied to the entire vehicle may be smaller than the decreasing speed of the braking force correlated with the decrease mode of the brake operation amount BPInput, which may give the driver a feeling of catching. .

  Therefore, in the vehicle braking system of the present embodiment, when it is determined that the brake operation amount BPInput is changing by the driver's brake operation, the pre-replacement control is not performed. When the brake operation amount BPInput changes during the execution of the pre-replacement control, the execution condition of the pre-replacement control does not hold, so the pre-replacement control is ended.

  Then, if the brake pedal 21 is in the increased state during the execution of the pre-replacement control, the pre-replacement control is ended and the holding control is performed. That is, when the brake operation amount BPInput is increased while the pre-replacement control is being performed, the pre-replacement control is ended, and when the increase of the brake operation amount BPInput is continued thereafter, the holding control is performed. This holding control is performed while the operation state of the brake pedal 21 is in the increase state. When this holding control is performed, in the brake actuator 30, the operation of the supply pumps 381 and 382 is continued, and the opening degree of the differential pressure control valves 321 and 322 is held. As a result, the raising amount RS which is the increase amount of the WC pressure in the wheel cylinders 22a to 22d accompanying the implementation of the pre-replacement control is held, and the control hydraulic braking force BPP is held. Therefore, in the vehicle braking system of the present embodiment, the holding control corresponds to an example of “suppression control” that suppresses the increase of the bulking amount RS by controlling the hydraulic braking device 20.

  In addition, when the operation state of the brake pedal 21 is reduced during execution of the pre-replacement control, the pre-replacement control is ended and the decrease control is performed. That is, when the brake operation amount BPInput is decreased while the pre-replacement control is being performed, the pre-replacement control is ended, and thereafter, the decrease control is performed when the decrease of the brake operation amount BPInput is continued. This decrease control is performed while the brake operation amount BPInput is in the decrease state. When this decrease control is performed, in the brake actuator 30, the operation of the supply pumps 381 and 382 is continued, and the opening degree of the differential pressure control valves 321 and 322 becomes large. As a result, the raising amount RS which is the increase amount of the WC pressure in the wheel cylinders 22a to 22d accompanying the implementation of the pre-replacement control is reduced, and the control hydraulic braking force BPP is reduced. The increasing speed of the opening degree of the differential pressure adjusting valves 321 and 322, that is, the decreasing speed of the raising amount RS is made larger as the decreasing speed of the brake operation amount BPInput is larger. For example, the decreasing speed of the lifting amount RS may be set to a speed such that the lifting amount RS becomes “0 (zero)” when the brake operation amount BPInput becomes “0 (zero)”.

  Incidentally, this reduction control is performed even after the termination of the pre-replacement control when the condition for implementing the same reduction control is satisfied. That is, the reduction control is performed when the execution condition is satisfied between the end point of the pre-replacement control and the start point of the replacement control. Further, even during the replacement control, the reduction control is performed when the execution condition is satisfied.

  Here, an example of a method of determining the operation state of the brake pedal 21 will be described. For example, it can be determined that the operation state of the brake pedal 21 is in the increasing state when the continuation time of the increase speed of the brake operation amount BPInput being equal to or higher than the increase determination speed reaches a predetermined determination speed time. . Further, when the continuation time of the decrease speed of the brake operation amount BPInput being equal to or higher than the decrease judgment speed reaches a predetermined judgment speed time, it can be judged that the operation state of the brake pedal 21 has become a decrease state. . Further, when the duration that the change speed of the brake operation amount BPInput is equal to or less than the holding determination speed reaches a predetermined determination speed time, it can be determined that the operation state of the brake pedal 21 has become the holding state. . However, it is desirable that the holding determination speed be a value smaller than the increase determination speed and the decrease determination speed.

  In addition, about determination of whether it is a reduction state, the continuation time of the state where the amount of reduction from the maximum value of brake operation amount BPInput at the time of this brake operation is more than a reduction judgment amount is acquired, and the continuation time When the predetermined time or more is reached, it may be determined that the reduction state is present.

  Further, from the viewpoint of suppressing a decrease in the recovery efficiency of the regenerative energy of the vehicle, it is desirable not to implement the pre-replacement control at the initial stage of braking when the driver's brake operation is started. That is, at the initial stage of braking, the regenerative braking force BPR applied to the vehicle by the second motor 14 which is a regenerative braking device is increased according to the increase of the brake operation amount BPInput. When the pre-replacement control is performed while the regenerative braking force BPR is thus increasing, the increasing speed of the braking force BPA applied to the entire vehicle is added to the increasing speed of the regenerative braking force BPR. The component of the increase speed of the control hydraulic braking force BPP accompanying the implementation of the replacement control is also included. Therefore, when the brake operation amount BPInput is relatively small, the vehicle deceleration DVS may reach the driver's desired deceleration and the brake operation amount BPInput may not be further increased. In this case, although it is possible to increase the regenerative braking force BPR as the second motor 14, the regenerative braking force BPR is not increased by holding the brake operation amount BPInput. That is, although the drivability due to the execution of the replacement control can be suppressed, the increase in the regenerative braking force BPR is limited because the pre-replacement control is performed, and the recovery efficiency of the vehicle's regenerative energy decreases. I will. Therefore, in the vehicle braking system according to the present embodiment, when the elapsed time T1 from the time when the driver starts the brake operation is less than the specified time T1Th, the above conditions (condition 2-1), (condition 2-) 2) Even if (Condition 2-3) and (Condition 2-4) are all satisfied, the pre-replacement control is not performed.

  The required braking force BPT can be calculated based on the brake operation amount BPInput and the MC pressure Pmc. For example, when the brake operation amount BPInput is equal to or less than the ineffective operation amount BPInputTh, since the MC pressure Pmc is “0 (zero)”, the required braking force BPT is calculated to be a larger value as the brake operation amount BPInput is larger. Be done. On the other hand, when the brake operation amount BPInput is larger than the ineffective operation amount BPInputTh, the required braking force BPT corresponds to the required braking force when the brake operation amount BPInput reaches the ineffective operation amount BPInputTh and the magnitude of the MC pressure Pmc. It is the sum of the addition amount.

  However, when the pre-replacement control is performed as described above, the MC pressure Pmc is reduced, which may be against the driver's will and the required braking force BPT may be reduced. Therefore, in the vehicle braking system according to the present embodiment, the required braking force at the time when the brake operation amount BPInput reaches the ineffective operation amount BPInputTh, the additional amount according to the magnitude of the MC pressure Pmc, and the control before replacement. The reduction amount of the MC pressure Pmc accompanying the implementation, that is, the sum of the correction amount corresponding to the lifting amount RS at that time.

Next, a processing routine executed by the brake control unit 104 of the control device 100 when the driver performs a brake operation will be described.
First, with reference to the flowchart shown in FIG. 8, in order to determine the start timing of the pre-replacement control and the replace control when the pre-replacement control, the holding control, the decrease control and the replace control are not performed. The processing routine executed by the brake control unit 104 will be described.

  As shown in FIG. 8, in this processing routine, the brake control unit 104 acquires an elapsed time T1 from the time when the brake operation is started, and determines whether this elapsed time T1 is equal to or longer than the specified time T1Th. It determines (step S11). In the case where the elapsed time T1 is less than the specified time T1Th, it can be determined that the regenerative braking force BPR applied to the vehicle may still be increased, so the implementation of the pre-replacement control is prohibited. Therefore, when the elapsed time T1 is less than the specified time T1Th (step S11: NO), the brake control unit 104 shifts the process to step S14 described later.

  On the other hand, when the elapsed time T1 is equal to or longer than the specified time T1Th (step S11: YES), the brake control unit 104 determines whether the start condition of the pre-replacement control is satisfied (step S12). In this case, when all of the above conditions (condition 2-1), (condition 2-2), (condition 2-3) and (condition 2-4) are satisfied, the start condition of the pre-replacement control It can be determined that Further, when at least one of the conditions (condition 2-1), (condition 2-2), (condition 2-3) and (condition 2-4) is not satisfied, the start condition of the pre-replacement control is satisfied It can be determined that it is not.

  When the start condition of the pre-replacement control is not satisfied (step S12: NO), the brake control unit 104 shifts the process to step S14 described later. On the other hand, when the start condition of the pre-replacement control is satisfied (step S12: YES), the brake control unit 104 sets the target value RSTr of the raising amount based on the brake operation amount BPInput, the MC pressure Pmc, etc. (Step S121). At this time, the brake control unit 104 may also set a target hydraulic pressure PmcTr that is correlated with the target value RSTr of the raising amount. Then, the brake control unit 104 starts the pre-replacement control (step S13), and ends the processing routine. In this case, the brake control unit 104 reduces the MC pressure based on the MC pressure Pmc and the vehicle speed VS (= VSTh3) at the start of the pre-replacement control, the target hydraulic pressure PmcTr, and the replacement control start speed VSTh1. That is, the increase speed DRS of the volume raising amount is set.

  In step S14, the brake control unit 104 determines whether the switching control start condition is satisfied. In this case, when all the above conditions (conditions 1-1) and (conditions 1-2) are satisfied, it can be determined that the start condition of the substitution control is satisfied. Further, when at least one of the conditions (conditions 1-1) and (conditions 1-2) does not hold, it can be determined that the switching control start condition does not hold. Then, if the start condition of the substitution control is satisfied (step S14: YES), the brake control unit 104 starts the substitution control (step S15), and the present processing routine is ended.

  On the other hand, if the replacement control start condition is not satisfied (step S14: NO), the brake control unit 104 sets the pre-replacement control start speed VSTh3 based on the MC pressure Pmc at that time (step S17). Thereafter, the brake control unit 104 once terminates the processing routine. Then, at the next control cycle, the brake control unit 104 executes this processing routine again.

  Next, with reference to the flowchart shown in FIG. 9, the processing routine executed by the brake control unit 104 to determine the start timing of the holding control, the decrease control and the replacement control when the pre-replacement control is being performed will be described. Do.

  As shown in FIG. 9, the brake control unit 104 determines whether or not the start condition of the replacement control is satisfied (step S21). When the pre-replacement control is performed, it may be determined that the start condition of the replacement control is satisfied when all the above conditions (conditions 1-1) and (condition 1-2) are satisfied. it can. Then, when the start condition of the replacement control is satisfied (step S21: YES), the brake control unit 104 ends the pre-replacement control and starts the replacement control (step S22), and ends the present processing routine.

  On the other hand, when the start condition of the replacement control is not satisfied (step S21: NO), the brake control unit 104 determines whether the start condition of the holding control is satisfied (step S23). When the pre-replacement control is being performed, at least one of the increase in the operation state of the brake pedal 21 and the decrease in the regenerative braking force BPR although the replacement control is not being performed. When one of the conditions is satisfied, it can be determined that the holding control start condition is satisfied.

  When the start condition of the holding control is satisfied (step S23: YES), the brake control unit 104 ends the pre-replacement control and starts the holding control (step S24), and the present processing routine is ended. On the other hand, when the start condition of the holding control is not satisfied (step S23: NO), the brake control unit 104 determines whether the start condition of the decrease control is satisfied (step S25). When the pre-replacement control is being performed, it can be determined that the start condition of the decrease control is satisfied when the operation state of the brake pedal 21 is in the decrease state. When the start condition of the decrease control is satisfied (step S25: YES), the brake control unit 104 ends the pre-replacement control and starts the decrease control (step S26), and ends the processing routine. At this time, the brake control unit 104 sets the pressure increase speed of the MC pressure, that is, the decrease speed of the lifting amount according to the decrease speed of the brake operation amount BPInput.

  On the other hand, when the start condition of the decrease control is not satisfied (step S25: NO), the brake control unit 104 once ends this processing routine. That is, the brake control unit 104 continues the implementation of the pre-replacement control. Also, at the next control cycle, the brake control unit 104 executes this processing routine again.

  In the processing routine shown in FIG. 9, the order of execution of the determination step may be changed as appropriate. For example, first, it is determined whether or not the start condition of decrease control is satisfied (step S25), and if the start condition of decrease control is not satisfied, whether the start condition of hold control is satisfied The determination process (step S23) may be performed. Then, when the start condition of the holding control is not satisfied, it may be determined whether or not the start condition of the substitution control is satisfied (step S21).

  Next, with reference to the flowchart shown in FIG. 10, the processing routine executed by the brake control unit 104 to determine the start timing of the pre-replacement control, the decrease control, and the replace control when the holding control is performed will be described. Do.

  As shown in FIG. 10, the brake control unit 104 determines whether or not the start condition of the substitution control is satisfied (step S31). When the holding control is performed, the regenerative braking force BPR is not “0 (zero)”, and the vehicle body speed VS of the vehicle is less than the switching control start speed VSTh1 and is equal to or higher than the switching control end speed VSTh2. Also, when all of the fact that the operation state of the brake pedal 21 is the holding state is satisfied, it can be determined that the start condition of the switching control is satisfied. Then, when the start condition of the substitution control is satisfied (step S31: YES), the brake control unit 104 ends the holding control and starts the substitution control (step S32), and the present processing routine is ended.

  On the other hand, when the start condition of substitution control is not satisfied (step S31: NO), the brake control unit 104 determines whether the start condition of control before substitution is satisfied (step S33). If retention control is being performed, before all the conditions (conditions 2-1), (conditions 2-2), (conditions 2-3) and (conditions 2-4) described above are satisfied, before replacement It can be determined that the control start condition is satisfied. Then, if the start condition of the pre-replacement control is satisfied (step S33: YES), the brake control unit 104 ends the holding control and starts the pre-replacement control (step S34), and terminates the present processing routine. . In addition, the calculation method of increase speed DRS of the amount of volume increase when implementing control before substitution in this case is mentioned later.

  On the other hand, in step S33, when the start condition of the pre-replacement control is not satisfied (NO), the brake control unit 104 determines whether the decrease control start condition is satisfied (step S35). When the holding control is performed, it can be determined that the start condition of the decrease control is satisfied when the operation state of the brake pedal 21 is in the decrease state. Then, when the start condition of the decrease control is not satisfied (step S35: NO), the brake control unit 104 once ends the present processing routine. That is, the brake control unit 104 continues the implementation of the holding control. Also, at the next control cycle, the brake control unit 104 executes this processing routine again.

  On the other hand, when the start condition of the decrease control is satisfied (step S35: YES), the brake control unit 104 ends the holding control and starts the decrease control (step S36), and ends the processing routine. When the reduction control is performed, the brake control unit 104 sets the brake actuator 30 so that the reduction speed of the raising amount RS, that is, the reduction speed of the control hydraulic braking force BPP decreases as the reduction speed of the brake operation amount BPInput decreases. Control.

  In the processing routine shown in FIG. 10, the order of execution of the determination step may be changed as appropriate. For example, first, determination processing (step S35) is performed to determine whether the start condition of decrease control is satisfied, and if the start condition of decrease control is not satisfied, the start condition of pre-replacement control is satisfied or not The determination process (step S33) may be performed. Then, when the start condition of the pre-replacement control is not satisfied, the determination process (step S31) may be performed to determine whether the start condition of the replacement control is satisfied.

  Next, with reference to the flowchart shown in FIG. 11, a description will be given of the processing routine executed by the brake control unit 104 to determine the start timing of the pre-replacement control, the holding control, and the replace control when reduction control is being performed. Do.

  As shown in FIG. 11, the brake control unit 104 determines whether the lifting amount RS reduced by the execution of the reduction control is equal to "0 (zero)" (step S401). If the raising amount RS is equal to “0 (zero)” (step S401: YES), the brake control unit 104 ends the reduction control (step S402) and ends the present processing routine. In this case, the brake control unit 104 is in a state out of control where the reduction control, the holding control, the pre-replacement control and the replacement control are not performed. On the other hand, when the raising amount RS is larger than “0 (zero)” (step S41: NO), the brake control unit 104 determines whether the start condition of the substitution control is satisfied (step S41). When the reduction control is being performed, the regenerative braking force BPR is not “0 (zero)”, and the vehicle body speed VS of the vehicle is less than the replacement control start speed VSTh1 and greater than or equal to the replacement control end speed VSTh2. Also, when all of the fact that the operation state of the brake pedal 21 is the holding state is satisfied, it can be determined that the start condition of the switching control is satisfied. Then, when the start condition of the replacement control is satisfied (step S41: YES), the brake control unit 104 ends the decrease control and starts the replacement control (step S42), and ends the processing routine.

  On the other hand, when the start condition of substitution control is not satisfied (step S41: NO), the brake control unit 104 determines whether the start condition of control before substitution is satisfied (step S43). If reduction control is being performed, before all of the above conditions (condition 2-1), (condition 2-2), (condition 2-3) and (condition 2-4) are satisfied, before replacement It can be determined that the control start condition is satisfied. Then, if the start condition of the pre-replacement control is satisfied (step S43: YES), the brake control unit 104 ends the decrease control and starts the pre-replacement control (step S44), and terminates the processing routine. . In addition, the calculation method of increase speed DRS of the amount of volume increase when implementing pre-replacement control in this case will be described later.

  On the other hand, in step S43, when the start condition of the pre-replacement control is not satisfied (NO), the brake control unit 104 determines whether the start condition of the holding control is satisfied (step S45). When the reduction control is being performed, the operating state of the brake pedal 21 is in the increasing state, the regenerative braking force BPR is reduced although the substitution control is not being performed, and the vehicle body speed VS of the vehicle is When at least one of the switching control end speed VSTh2 and the operating state of the brake pedal 21 in the holding state is satisfied, it can be determined that the holding control start condition is satisfied. .

  Then, when the start condition of the holding control is not satisfied (step S45: NO), the brake control unit 104 temporarily ends the present processing routine. That is, the brake control unit 104 continues the implementation of the reduction control. Also, at the next control cycle, the brake control unit 104 executes this processing routine again. On the other hand, when the start condition of the holding control is satisfied (step S45: YES), the brake control unit 104 ends the decrease control and starts the holding control (step S46), and ends the present processing routine.

  In addition, in the processing routine shown in FIG. 11, when the raising amount RS is larger than "0 (zero)" (step S401: NO), the order of executing the subsequent determination steps may be changed as appropriate. . For example, determination processing (step S45) is performed to determine whether the holding control start condition is satisfied, and if the holding control start condition is not satisfied, it is determined whether the pre-replacement control start condition is satisfied. The process (step S43) may be performed. Then, when the start condition of the pre-replacement control is not satisfied, the determination process (step S41) may be performed to determine whether the start condition of the replacement control is satisfied.

  Next, with reference to the flowchart shown in FIG. 12, a description will be given of the processing routine executed by the brake control unit 104 to determine the start timing of the pre-replacement control, the holding control and the decrease control when the substitution control is being performed. Do.

  As shown in FIG. 12, the brake control unit 104 determines whether the start condition of the pre-replacement control is satisfied (step S51). When the substitution control is being performed, before substitution, when all the above conditions (condition 2-1), (condition 2-2), (condition 2-3) and (condition 2-4) are satisfied. It can be determined that the control start condition is satisfied. Then, when the start condition of the pre-replacement control is satisfied (step S51: YES), the brake control unit 104 ends the replacement control and starts the pre-replacement control (step S52), and ends the processing routine. .

  On the other hand, when the start condition of the pre-replacement control is not satisfied (step S51: NO), the brake control unit 104 determines whether the start condition of the holding control is satisfied (step S53). When switching control is being performed, the vehicle speed VS of the vehicle reaches the switching control end speed VSTh2, and the regenerative braking force BPR has become "0 (zero)", and the operation state of the brake pedal 21 is in an increasing state It is possible to determine that the start condition of the holding control is satisfied when at least one of the becoming becomes true.

  Then, if the start condition of the holding control is satisfied (step S53: YES), the brake control unit 104 ends the substitution control and starts the holding control (step S54), and the present processing routine is ended. On the other hand, when the start condition of the holding control is not satisfied (step S53: NO), the brake control unit 104 determines whether the start condition of the decrease control is satisfied (step S55). When the substitution control is performed, it can be determined that the start condition of the decrease control is satisfied when the operation state of the brake pedal 21 is in the decrease state.

  When the start condition of the decrease control is satisfied (step S55: YES), the brake control unit 104 ends the substitution control and starts the decrease control (step S56). In this case, the brake control unit 104 reduces the lifting amount RS at a speed corresponding to the decreasing speed of the brake operation amount BPInput. On the other hand, when the start condition of the decrease control is not satisfied (step S55: NO), the brake control unit 104 once ends the processing routine. That is, the brake control unit 104 continues the implementation of the substitution control. Also, at the next control cycle, the brake control unit 104 executes this processing routine again.

  In the processing routine shown in FIG. 12, the order of execution of the determination step may be changed as appropriate. For example, first, it is determined whether or not the start condition of decrease control is satisfied (step S55), and if the start condition of decrease control is not satisfied, whether the start condition of hold control is satisfied The determination process (step S53) may be performed. Then, when the start condition of the holding control is not satisfied, it may be determined whether or not the start condition of the pre-replacement control is satisfied (step S51).

  Next, with reference to a timing chart shown in FIG. 13, an example of a calculation method of the increase speed of the bulking amount when transitioning from the holding control to the pre-replacement control will be described. FIG. 13 illustrates a timing chart when the control performed by the brake control unit 104 is shifted in the order of the pre-replacement control, the holding control, and the pre-replacement control.

  As shown in FIGS. 13A and 13B, when the pre-replacement control is started at the first timing t41, the MC pressure Pmc in the master chambers 621 and 622 is reduced toward the target fluid pressure PmcTr. Thus, the lifting amount RS is increased. Then, when the operation state of the brake pedal 21 is shifted from the holding state to the increase state at the second timing t42 during the execution of such pre-replacement control, the pre-replacement control is ended and the holding control is started. Therefore, from the second timing t42, the lifting amount RS is held by the execution of the holding control. Then, when the operation state of the brake pedal 21 is shifted from the increase state to the holding state at the third timing t43 during the holding control, the holding control is ended and the pre-replacement control is started.

  Here, for convenience of explanation and understanding here, the pre-replacement control started from the first timing t41 is referred to as "first pre-replacement control", and the pre-replacement control started from the third timing t43 is referred to as "second It is called "pre-replacement control".

  Since the MC pressure Pmc is held in the period from the second timing t42 to the third timing t43, even if the MC pressure Pmc is decreased at a speed equal to the reduction speed at the time of the execution of the first replacement control, the second In the pre-replacement control, it is difficult to reduce the MC pressure Pmc to the target fluid pressure PmcTr. Therefore, in the vehicle braking system of the present embodiment, when performing the second pre-replacement control, the increase speed DRS of the raising amount correlated with the pressure reduction speed of the MC pressure is set again. At this time, the increase speed DRS of the bulking amount can be calculated by using the following relational expression (Expression 1). The vehicle speed VS at the start of the pre-replacement control (in this case, the third timing t43) is "VS1", and the current vehicle speed VS is "VS2". Further, the switching control start speed, which is the vehicle speed at the start of the switching control, is set to "VSTh1".

If the increase rate DRS calculated in this way is too large, the pressure reduction rate of the MC pressure Pmc at the time of implementation of the second pre-replacement control becomes too large, and drivability declines during the implementation of the second pre-replacement control. There is a risk of Also, if the calculated increase speed DRS is too small, even if the second pre-replacement control is performed, the amount of decrease in the MC pressure Pmc during the subsequent replacement control is not reduced so much, and the replacement control is being performed. There is a possibility that the reduction effect of drivability may become small.

  Therefore, as indicated by the alternate long and two short dashes line in FIG. 13B, the upper limit DRSU of the increase rate of the bulking amount is provided, and as indicated by the alternate long and short dash line in FIG. Lower limit value DRSL of is provided. The lower limit value DRSL of the increasing speed is set to a value equal to or slightly smaller than the increasing speed of the lifting amount during execution of the first replacement control. Further, the upper limit value DRSU of the increase speed is set to a value that can suppress the displacement speed of the brake pedal 21 in the braking direction due to the pressure reduction of the MC pressure Pmc within the allowable range.

  Then, the brake control unit 104 compares the increase speed DRS, the upper limit DRSU of the increase speed, and the lower limit DRSL of the increase speed calculated by the above-mentioned relational expression (Equation 1), and sets the middle value to the second pre-replacement control. It is set as increase speed DRS of the raising amount in implementation.

  Although the case where the hold control is shifted to the pre-replacement control is described here, the shift control is also shifted from the shift control to the pre-replacement control even when the pressure reduction control is shifted to the pre-replacement control. Even in the same manner as described above, it is possible to set the increase speed DRS of the bulking amount. Further, by substituting the control start velocity VSTh3 before substitution into “VS1” of the above-mentioned relational expression (Equation 1), the substitution prior to replacement which is performed due to the vehicle speed VS decreasing to the control start velocity VSTh3 before substitution It is also possible to set the speed of increase DRS of the raising amount in the control (corresponding to the first pre-replacement control in the example shown in FIG. 13).

As described above, according to the above configuration and operation, the following effects can be obtained.
(1) At the time of deceleration of the vehicle accompanying the brake operation, the pre-replacement control is performed before the implementation of the substitute control. In this pre-replacement control, brake fluid is supplied from the inside of the master chambers 621 and 622 into the wheel cylinders 22a to 22d by actuation of the brake actuator 30. That is, prior to the execution of the replacement control, the MC pressure Pmc in the master chambers 621 and 622 is reduced. Therefore, when the control hydraulic braking force BPP is increased by the switching control started thereafter, the amount of pressure reduction of the MC pressure Pmc can be reduced compared to the case where the control before switching is not performed in advance. As a result, the decrease in the operation reaction force accompanying the execution of the substitution control is suppressed, and as a result, the displacement amount of the brake pedal 21 in the braking direction is less likely to be large. Moreover, during the implementation of the pre-replacement control, the reduction of the regenerative braking force BPR resulting from the implementation of the same pre-replacement control is not performed. Therefore, even if the pre-replacement control is performed, the reduction in the recovery efficiency of the regenerative energy of the vehicle is suppressed. Therefore, it is possible to suppress the decrease in drivability when performing the substitution control while suppressing the decrease in the recovery efficiency of the regenerative energy of the vehicle.

  (2) In the vehicle braking system of the present embodiment, during the execution of the pre-replacement control, the pressure increase rate of the WC pressure in the wheel cylinders 22a to 22d is higher than the pressure increase rate during the replacement control. Be made smaller. Thereby, the pressure reduction rate of the MC pressure Pmc in the master chamber 621, 622 during the execution of the pre-replacement control can be made smaller than the pressure reduction rate during the execution of the replacement control. Therefore, it is possible to make it difficult to displace the brake pedal 21 in the braking direction or to make the increase of the deceleration DVS of the vehicle small, and it becomes difficult for the driver to feel uncomfortable when performing the pre-replacement control. Therefore, it is possible to suppress a decrease in drivability accompanying the implementation of the pre-replacement control.

  (3) In addition, when the operation state of the brake pedal 21 is increased during the execution of the pre-replacement control, the raising control RS is performed to hold the raising amount RS. Therefore, even when the operating state of the brake pedal 21 is in the increasing state, the increasing speed of the braking force BPA applied to the entire vehicle deviates from the speed intended by the driver as compared to the case where the pre-replacement control is performed. It becomes difficult. Therefore, it is possible to suppress the decrease in drivability when the brake operation amount BPInput starts to be increased while the pre-replacement control is being performed.

  (4) On the other hand, when the operation state of the brake pedal 21 is reduced during the execution of the pre-replacement control, the increase amount RS is reduced by the execution of the reduction control. Therefore, it is possible to cause the brake actuator 30 to perform the operation according to the driver's intention to reduce the braking force BPA applied to the entire vehicle. Therefore, when the brake operation amount BPInput starts to be decreased while the pre-replacement control is being performed, it is possible to make it difficult for the driver to get a feeling of catching and to suppress a decrease in drivability.

  (5) As described above, when the operation state of the brake pedal 21 becomes the increase state or the decrease state during the execution of the pre-replacement control, the pre-replacement control is ended. After that, when the operation state of the brake pedal 21 becomes the holding state, the pre-replacement control is implemented only when the replacement control is not yet performed. Therefore, it is possible to lower the MC pressure Pmc in the master chambers 621 and 622 at the time when the replacement control is started thereafter. Therefore, even if the brake operation amount BPInput is changed during the execution of the pre-replacement control, it is possible to suppress the decrease in drivability associated with the execution of the replacement control.

  (6) Further, after the pre-replacement control ends, the operation state of the brake pedal 21 may be reduced. In this case, when the operation state of the brake pedal 21 is in the decrease state, the decrease control is performed, and the raising amount RS is also decreased according to the decrease of the brake operation amount BPInput. That is, it is possible to cause the brake actuator 30 to perform an operation according to the driver's intention to reduce the braking force BPA applied to the entire vehicle. Therefore, when the driver decreases the brake operation amount BPInput after the termination of the pre-replacement control, it is possible to make it difficult for the driver to be caught by the driver and to suppress a decrease in drivability.

  (7) In the vehicle braking system of the present embodiment, the larger the difference between the MC pressure Pmc in the master chambers 621 and 622 and the specified value of the target fluid pressure PmcTr, the larger the pre-replacement control start speed VSTh3. That is, the pre-transfer control is started when the vehicle body speed VS of the vehicle is high. As described above, by making the start timing of the pre-replacement control variable based on the above difference, it is possible to suppress an increase in the pressure reduction speed of the MC pressure Pmc during the execution of the pre-replacement control. Therefore, it is possible to suppress a decrease in drivability accompanying the implementation of the pre-replacement control.

  (8) By setting the target value RSTr of the raising amount to an appropriate value according to the brake operation amount BPInput and the MC pressure Pmc, it is suppressed that the decreasing speed of the MC pressure Pmc during execution of the pre-replacement control becomes large. Be done. Therefore, it is possible to suppress a decrease in drivability accompanying the implementation of the pre-replacement control.

  (9) When the MC pressure Pmc in the master chambers 621 and 622 is less than the specified hydraulic pressure PmcThL, it is determined that there is almost no deterioration in drivability even if the replacement control is performed without performing the pre-replacement control. be able to. Therefore, pre-replacement control is not performed in such a case. Therefore, unnecessary implementation of the pre-replacement control can be suppressed.

  (10) Also, when the regenerative braking force BPR applied to the vehicle is less than the specified regenerative braking force BPRTh, it is determined that the drivability hardly decreases even if the replacement control is performed without implementing the pre-replacement control. can do. Therefore, pre-replacement control is not performed in such a case. Therefore, unnecessary implementation of the pre-replacement control can be suppressed.

  (11) In addition, when elapsed time T1 from the start of the brake operation is less than the specified time T1Th, it can be determined that the regenerative braking force BPR may still be increased, so pre-replacement control is not performed. It is like that. Thereby, it becomes possible to carry out the pre-replacement control after the regenerative braking force BPR becomes large. Therefore, it is possible to suppress the decrease in the recovery efficiency of the regenerative energy of the vehicle.

The above embodiment may be changed to another embodiment as described below.
· Whether the regenerative braking force BPR that the second motor 14 applies to the vehicle by the brake operation is increased instead of the determination process whether the elapsed time T1 from the start of the brake operation is less than the specified time T1Th It may be replaced by the determination processing of whether or not. In this case, when it is determined that the regenerative braking force BPR is not increased any more at the time of the current brake operation, the pre-replacement control is started at an appropriate timing. Even in this case, since the pre-replacement control can be performed after the regenerative braking force BPR becomes large, it is possible to suppress a decrease in the recovery efficiency of the vehicle's regenerative energy accompanying the implementation of the pre-replacement control.

  It may be determined that the regenerative braking force BPR is to be held when the continuation time of the state in which the change speed of the regenerative braking force BPR is less than the specified speed becomes equal to or longer than a predetermined determination time. .

  In the above embodiment, when the regenerative braking force BPR is less than the specified regenerative braking force BPRTh, the pre-replacement control is not performed. Therefore, even if the process of determining whether the elapsed time T1 from the start of the brake operation is less than the specified time T1Th is omitted, the occurrence of the event that the pre-transfer control is performed at a stage where the regenerative braking force BPR is still small. Can be suppressed.

  -Even if the MC pressure Pmc in the master chambers 621 and 622 is less than the specified hydraulic pressure PmcThL, all of the above conditions (Condition 2-2), (Condition 2-3) and (Condition 2-4) are satisfied. If it is, the pre-replacement control may be performed.

  ・ Even if all of the above conditions (Condition 2-1), (Condition 2-3) and (Condition 2-4) are satisfied, even if the regenerative braking force BPR is less than the specified regenerative braking force BPRTh, switching is performed. Pre-control may be performed.

The target fluid pressure PmcTr in the pre-replacement control may be fixed at a constant value regardless of the MC pressure Pmc and the brake operation amount BPInput.
-The pressure reduction speed of MC pressure and the control start speed VSTh3 during substitution control may be fixed at a constant value regardless of the MC pressure Pmc or the brake operation amount BPInput. In this case, the MC pressure Pmc at the start time of the replacement control is varied according to the MC pressure Pmc at the start time of the pre-replacement control and the brake operation amount BPInput. However, even in the case where such a control configuration is adopted, it is possible to suppress a decrease in drivability due to the implementation of the replacement control as compared with the case where the pre-replacement control is not performed before the implementation of the replacement control.

  After the termination of the pre-replacement control, when the operation state of the brake pedal 21 is in the decrease state, not the decrease control but the hold control may be performed. However, when it is determined that the brake operation amount BPInput becomes “0 (zero)”, it is desirable to operate the brake actuator 30 so as to make the raising amount RS “0 (zero)”.

  -When the holding control is started because the operating state of the brake pedal 21 is increased during the execution of the pre-replacement control, the operating state of the brake pedal 21 is held during the holding control. It is not necessary to start the pre-replacement control. In this case, even if the operation state of the brake pedal 21 is in the holding state, the holding control may be continued until the start condition of the substitution control is satisfied.

  · If reduction control is started because the operation state of the brake pedal 21 is reduced during execution of pre-replacement control, even if the operation state of the brake pedal 21 is held during execution of the reduction control. It is not necessary to start the pre-replacement control. In this case, the holding control may be performed instead of the pre-replacement control until the start condition of the substitution control is satisfied even if the operation state of the brake pedal 21 becomes the holding state.

  When the operation state of the brake pedal 21 is reduced during execution of the pre-replacement control, the decrease control may not be performed, but the implementation of the pre-replacement control may be continued. However, when it is determined that the brake operation amount BPInput becomes “0 (zero)”, it is desirable to end the pre-replacement control and operate the brake actuator 30 so as to make the raising amount RS “0 (zero)”.

  · If the suppression control performed when the operation state of the brake pedal 21 is in the increase state can suppress the increase of the volume raising amount RS by the execution of the pre-replacement control, the holding for holding the volume raising amount RS Control other than control may be adopted. For example, as the suppression control, control may be employed in which the raising amount RS is increased at an increasing speed smaller than the increasing speed DRS of the raising amount at the time of implementation of the pre-replacement control.

  In the above embodiment, during the execution of the pre-replacement control, the regenerative braking force BPR is not reduced. However, the present invention is not limited to this, and the regenerative braking force BPR may be slightly reduced even during the execution of the pre-replacement control. However, it is preferable that the decrease speed and the decrease amount of the regenerative braking force BPR at this time be smaller than the increase speed and the increase amount of the control hydraulic braking force BPP accompanying the implementation of the pre-replacement control.

When the operation state of the brake pedal 21 is in the increase state during the execution of the pre-replacement control, the suppression control may not be performed and the implementation of the pre-replacement control may be continued.
The booster device included in the hydraulic pressure supply device 50 is a device other than a device that assists the brake operation force using the operation of the engine 11 if the device has a configuration in which the brake pedal 21 is displaced according to the slide of the master piston. It may be another device. For example, the booster device may be a hydraulic booster device.

  In the case of a so-called in-line configuration, the brake actuator includes a differential pressure adjusting valve and a supply pump capable of pumping the brake fluid from the inside of the first and second master chambers 621 and 622 of the master cylinder 51. It may be something other than the above-mentioned brake actuator 30 composition.

  The master cylinder has a timing at which the communication between the first and second master chambers 621 and 622 and the atmospheric pressure reservoir 53 is cut off (also referred to as “cut-off timing”), the second motor 14 which is a regenerative braking device. It may be configured to coincide with the timing at which the regenerative braking force BPR applied to the vehicle reaches the limit value (also referred to as “limit reaching timing”).

  Also, the master cylinder may have a configuration in which the shutoff timing is different from the limit arrival timing. For example, the master cylinder may be configured such that the shutoff timing is later than the limit arrival timing. In this case, even if the regenerative braking force BPR applied to the vehicle by the second motor 14 reaches the limit value, the communication between the first and second master chambers 621 and 622 and the atmospheric pressure reservoir 53 is still continued. Further, the brake pedal 21 is further stepped on, whereby the communication between the first and second master chambers 621 and 622 and the atmospheric pressure reservoir 53 is cut off.

  The vehicle provided with the braking system of the vehicle according to the above-described embodiment may be a single-motor hybrid vehicle in addition to the two-motor hybrid vehicle as long as the vehicle includes the engine 11. In addition, when the booster device is a hydraulic booster device, the vehicle may be an electric vehicle without the engine 11. In addition, when a generator is provided as the regenerative braking device, the vehicle may be provided with only the engine 11 as a drive source.

The brake operating member may be any other device than the brake pedal 21 (for example, a brake lever) as long as it is operated by the driver.
Next, technical ideas that can be grasped from the above-described embodiment and other embodiments will be additionally described below.

  (A) It is preferable that the control device does not decrease the regenerative braking force interlocked with the hydraulic braking force caused by the pressure increase of the hydraulic pressure in the wheel cylinder when performing the pre-replacement control. As described above, during the implementation of the pre-replacement control, the reduction of the drivability due to the implementation of the replacement control is suppressed without reducing the regenerative energy recovery efficiency of the vehicle by not reducing the regenerative braking force. Will be able to

  14 Second motor as an example of regenerative braking device 20 Hydraulic braking device constituting a braking system of a vehicle 22a to 22d Wheel cylinder 321, 322 Differential pressure adjusting valve 381, 382 Supply pump 51: master cylinder 621 622 master chamber 100: control device constituting the braking system of the vehicle FL, FR, RL, RR wheel: BPInput brake operation amount BPP: control hydraulic braking force BPR: Regenerative braking force, BPRTh: Specified regenerative braking force, BPT: Required braking force, Pmc: Master cylinder pressure (MC pressure) which is a basic hydraulic pressure, PmcThL: Specified hydraulic pressure, PmcTr: Target hydraulic pressure, RS: Lifting amount, T1 ... elapsed time, T1Th ... prescribed time, VS ... body speed, VSTh1 ... replacement control start speed, VSTh3 ... control start speed before replacement.

Claims (12)

A hydraulic braking device for applying a hydraulic braking force to a vehicle by adjusting a hydraulic pressure in a wheel cylinder provided for a wheel, a regenerative braking device for applying a regenerative braking force to a vehicle, and the hydraulic braking device A controller for controlling the vehicle based on a required braking force on the vehicle,
The fluid pressure braking device includes a master cylinder that generates a base fluid pressure, which is a fluid pressure corresponding to a brake operation, in a master chamber, and a differential pressure adjusting valve disposed in a path between the master cylinder and the wheel cylinder. And a pump for drawing up the brake fluid from the master chamber and discharging the brake fluid to a path closer to the wheel cylinder than the differential pressure adjustment valve.
The control device reduces the regenerative braking force applied to the vehicle by the regenerative braking device at the time of deceleration of the vehicle accompanying the brake operation, and applies the brake fluid from the master chamber to the wheel cylinder by the operation of the pump. In a vehicle braking system that performs substitution control that increases the hydraulic braking force by supplying
Wherein the control device,
Bed during deceleration of the vehicle due to the rake operation before the implementation of the swap control, implement the swap before control pressure increasing the hydraulic pressure in the wheel cylinder by operating the pump,
A vehicle braking system characterized in that the implementation of the same pre-replacement control is ended when the amount of brake operation changes during the implementation of the pre-replacement control . If a reference increase圧速degree pressure increase rate of the hydraulic pressure in the wheel cylinder during the practice of prior SL swap control,
In the pre-replacement control, the control device operates the hydraulic braking device to set the brake fluid in the master chamber so that the pressure increase rate of the fluid pressure in the wheel cylinder is smaller than the reference pressure increase rate. A braking system for a vehicle according to claim 1, wherein the braking system is reduced. If the raised amount pressure increase amount before Symbol swap precontrol hydraulic pressure in the wheel cylinder according to the practice of,
Wherein the controller, when the brake operation amount during that implement the swap before control is increased terminates the implementation of the swap before control, when subsequently has also been continuously increased in the same amount of brake operation is The vehicle braking system according to claim 1 or 2, wherein the suppression control is performed to suppress an increase in the amount of raising by operation of the hydraulic braking device. If the raised amount pressure increase amount before Symbol swap precontrol hydraulic pressure in the wheel cylinder according to the practice of,
Wherein the controller, when the brake operation amount during that implement the swap before control is decreased terminates the implementation of the swap before control, when thereafter being continued decrease in the amount of brake operation is The vehicle braking system according to claim 1 or 2, wherein a reduction control is performed to reduce the amount of raising by the operation of the hydraulic braking device. Wherein the control device, after completion of the implementation of response particular brake operation amount changes the swap before control the midst of performing said swap precontrol, in a situation where the brake operation is continued The vehicle braking system according to claim 3 or 4, wherein the pre-replacement control is performed when the same brake operation amount no longer changes and the replacement control is not performed. If the raised amount pressure increase amount before Symbol swap precontrol hydraulic pressure in the wheel cylinder according to the practice of,
The control device according to claim 1 wherein the amount of brake operation after the completion of implementation of the swap before control when it is reduced, for implementing a reduction control to reduce the raised amount by controlling the fluid pressure braking system Or the braking system of the vehicle of Claim 2. The start condition of the replacement control includes that the vehicle body speed of the vehicle has become less than the replacement control start speed,
The implementation conditions of the pre-replacement control include that the vehicle body speed of the vehicle is equal to or higher than the replacement control start speed and equal to or lower than the pre-replacement control start speed that is larger than the same replacement control start speed.
The controller is
When the pre-replacement control is not yet performed at the time of deceleration of the vehicle accompanying the brake operation, the larger the difference between the base fluid pressure and the target fluid pressure, the larger the pre-replacement control start speed.
When the execution condition of the pre-replacement control is satisfied, the basic hydraulic pressure in the master chamber is decreased toward the target fluid pressure by controlling the hydraulic braking device by performing the pre-replacement control. The braking system of the vehicle according to any one of claims 1 to 6. The start condition of the replacement control includes that the vehicle body speed of the vehicle has become less than the replacement control start speed,
The implementation conditions of the pre-replacement control include that the vehicle body speed of the vehicle is equal to or higher than the replacement control start speed and equal to or lower than the pre-replacement control start speed that is larger than the same replacement control start speed.
When the pressure increase amount of the fluid pressure in the wheel cylinder by the execution of the control before replacement is a raising amount:
The controller is
During deceleration of the vehicle by the braking operation, on the basis of the basic hydraulic pressure and the brake operation amount, it sets a target value of the raising amount,
When the execution condition of the pre-replacement control is satisfied, the raising amount is increased toward the target value of the raising amount by controlling the hydraulic braking device by performing the pre-replacement control. A braking system for a vehicle according to any one of the preceding claims. The control device does not execute the pre-replacement control when the base fluid pressure in the master chamber is less than the prescribed fluid pressure even when the vehicle is decelerating due to a brake operation. A braking system for a vehicle according to any one of the preceding claims. The control device does not execute the pre-transfer control when the regenerative braking force applied to the vehicle by the regenerative braking device is less than a prescribed regenerative braking force even when the vehicle is decelerating due to a brake operation. The vehicle braking system according to any one of claims 1 to 9. The vehicle braking system according to any one of claims 1 to 10, wherein the control device does not execute the pre-replacement control when an elapsed time from a start time of a brake operation is less than a specified time. The control device according to any one of claims 1 to 10, wherein the control before replacement is not performed when the regenerative braking force applied to the vehicle by the regenerative braking device is increased by a brake operation. Vehicle braking system.