JP5978943B2 - Braking control device - Google Patents

Description

  The present invention relates to a braking control device that performs regenerative cooperative control in which a hydraulic braking device that generates a master cylinder hydraulic pressure by a driver's braking operation and a regenerative braking device that generates a regenerative braking torque by rotation of a drive wheel are cooperatively operated. About.

  Conventionally, during the period from the start of a braking operation to a predetermined stroke, the increase in braking hydraulic pressure by the hydraulic braking device is limited, and the braking torque corresponding to the limitation is obtained by the regenerative braking torque, improving the recovery efficiency of regenerative energy. There is a known braking control device (see, for example, Patent Document 1).

  Further, in this braking control device, the hydraulic braking device is capable of actively increasing and decreasing the braking hydraulic pressure, and so-called ABS (Antilock Brake System) control for reducing the braking hydraulic pressure of the slip wheel during braking. An executable brake actuator is provided.

JP 2006-96218 A

In a braking device provided with a brake actuator capable of executing ABS control, when slip occurs on the driving wheel during braking, the ABS control is executed by switching from regenerative braking to friction braking.
At the time of such replacement, the hydraulic pressure control response is different between when the master cylinder hydraulic pressure is not limited and when it is limited.
That is, when the generation of the master cylinder hydraulic pressure is not limited, the control response is high because the pressure is increased using the master cylinder hydraulic pressure. On the other hand, when the generation of the master cylinder hydraulic pressure is restricted, the pressure increase is relatively delayed and the control response is delayed.

  For this reason, if the slip threshold is set based on a state of excellent responsiveness that does not limit the generation of master cylinder hydraulic pressure, a control delay will occur if changeover control is performed with the generation of master cylinder hydraulic pressure limited. , It took time to replace. In this case, a delay occurs in the recovery of the drive wheel slip.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a braking control device having high switching control responsiveness regardless of whether or not the master cylinder hydraulic pressure of the hydraulic braking device is limited. .

In order to achieve the above object, the braking control device of the present invention provides:
A braking torque control unit that controls a regenerative braking device and a brake actuator during a braking operation, and performs regenerative cooperative braking control that generates a driver-requested braking torque based on the regenerative braking torque and the friction braking torque;
Included in this braking torque control unit, during regenerative coordinated braking control, if the drive wheel slip exceeds a preset slip threshold, execute switching control to increase the friction braking torque by the brake actuator while reducing the regenerative braking torque A replacement control unit;
Included in the switching control unit, during braking operation, when the master cylinder hydraulic pressure generation is limited by the limiting means, the slip threshold is set to a value with a relatively small slip amount, and the master cylinder hydraulic pressure generation by the limiting means is not limited Sometimes, a threshold setting unit that sets the slip threshold to a relatively large slip amount;
A braking control device characterized by comprising:

In the braking control device of the present invention, the threshold setting unit sets the slip threshold to a relatively small slip amount when the master cylinder hydraulic pressure generation device restricts the generation of the master cylinder hydraulic pressure.
Therefore, when the hydraulic pressure control response is relatively low due to the generation restriction of the master cylinder hydraulic pressure, the switching control is executed relatively early when the driving wheel slip occurs, and the delay of the switching control can be suppressed.

1 is an overall system diagram illustrating a configuration of an electric vehicle to which a braking control device according to a first embodiment is applied. FIG. 2 is an overall block diagram illustrating a control system of the braking control device according to the first embodiment. FIG. 3 is a brake hydraulic pressure circuit diagram showing a VDC brake hydraulic pressure unit in the braking control device of the first embodiment. FIG. 3 is a mechanism explanatory diagram showing a relationship between a pedal stroke and a master cylinder hydraulic pressure in the braking control device of the first embodiment. It is a braking torque characteristic figure which shows the relationship between the driver request | requirement braking torque and master cylinder hydraulic pressure according to a pedal stroke (braking operation state). FIG. 5 is a braking torque characteristic diagram showing a relationship among an operation response braking torque, a pump-up braking torque, and a regenerative braking torque in the total braking torque. The flow of the driver request | requirement braking torque control performed with the integrated controller, brake controller, and motor controller in the brake control apparatus of Embodiment 1 is shown. 4 is a flowchart showing a flow of processing for switching control executed by an integrated controller in the brake control device of the first embodiment. It is a time chart which shows the operation example of the comparative example for comparing with the braking control apparatus of Embodiment 1, Comprising: The case where the slip amount is set to a relatively large value as a slip threshold is shown. It is a time chart which shows the operation example of the comparative example for comparing with the braking control apparatus of Embodiment 1, Comprising: The case where the slip amount is set to a relatively small value as a slip threshold is shown. FIG. 6 is a time chart showing an operation example of the braking control apparatus of Embodiment 1, showing an operation when the generation of the master cylinder hydraulic pressure is not restricted. FIG. FIG. 6 is a time chart showing an operation example of the braking control apparatus of Embodiment 1, showing an operation when the generation of the master cylinder hydraulic pressure is restricted. FIG. 6 is a flowchart showing a flow of processing for switching control executed by an integrated controller in the brake control device of the second embodiment. 12 is a flowchart showing a flow of processing for switching control executed by an integrated controller in the brake control device of the third embodiment.

Hereinafter, the best mode for realizing the braking control device of the present invention will be described based on the first embodiment shown in the drawings.
First, the configuration of the braking control device of the first embodiment will be described.
The configuration of the braking control device according to the first embodiment will be described by dividing it into “entire system configuration”, “regenerative braking device”, “control system”, “VDC brake hydraulic unit configuration”, and “master cylinder configuration”.

[Overall system configuration]
FIG. 1 shows a configuration of an electric vehicle by front wheel drive to which the braking control device of the first embodiment is applied. Hereinafter, based on FIG. 1, the whole structure of this braking control apparatus is demonstrated.

The braking torque generation system of the braking control device according to the first embodiment includes a hydraulic braking device 1 and a regenerative braking device 50.
The hydraulic braking device 1 includes a master cylinder hydraulic pressure generating device 10, a VDC brake hydraulic pressure unit 2 that is an existing VDC system (VDC is an abbreviation of “Vehicle Dynamics Control”), a left front wheel wheel cylinder 4FL, A front wheel wheel cylinder 4FR, a left rear wheel wheel cylinder 4RL, and a right rear wheel wheel cylinder 4RR are provided.

  The master cylinder hydraulic pressure generator 10 is applied to each of the front and rear wheels (the left front wheel FLW, the right front wheel FRW, the left rear wheel RLW, and the right rear wheel RRW) in order to generate a friction braking torque in accordance with a braking operation by the driver. Generate master cylinder hydraulic pressure. The master cylinder hydraulic pressure generator 10 includes a brake pedal 15, an electric booster 12, a master cylinder 13, and a reservoir 14. That is, the driver's brake depression force applied to the brake pedal 15 is boosted by the electric booster 12, and the master cylinder hydraulic pressure (primary hydraulic pressure and secondary hydraulic pressure) is generated by the primary piston and the secondary piston of the master cylinder 13. The master cylinder hydraulic pressure is detected by a master cylinder hydraulic pressure sensor 16 described later.

  The VDC brake hydraulic unit (brake actuator) 2 is a vehicle behavior control (= VDC control) that prevents skidding and ensures excellent running stability when the vehicle posture is disturbed due to high-speed corner entry or sudden steering operation. )I do.

The VDC brake hydraulic pressure unit 2 is disposed in a hydraulic system that connects the master cylinder hydraulic pressure generator 10 and the wheel cylinders 4FL, 4FR, 4RL, and 4RR.
This VDC brake hydraulic unit 2 has hydraulic pumps 22 and 22 (see FIG. 3) driven by a VDC motor 21 (see FIG. 3), and increases, holds, and reduces the wheel cylinder hydraulic pressure PW / CYL. Control. The VDC brake fluid pressure unit 2 and the master cylinder fluid pressure generator 10 are connected by a primary fluid pressure tube 61 and a secondary fluid pressure tube 62. The VDC brake hydraulic unit 2 and each wheel cylinder 4FL, 4FR, 4RL, 4RR are connected by a left front wheel hydraulic pipe 63, a right front wheel hydraulic pipe 64, a left rear wheel hydraulic pipe 65, and a right rear wheel hydraulic pipe 66. .

  The wheel cylinders 4FL, 4FR, 4RL, and 4RR are set to the brake disks of the front and rear wheels FLW, FRW, RLW, and RRW, and the hydraulic pressure from the VDC brake hydraulic pressure unit 2 is applied. The VDC brake fluid pressure unit 2 applies friction braking torque to the front and rear wheels by sandwiching the brake disc with the brake pads when fluid pressure is applied to the wheel cylinders 4FL, 4FR, 4RL, 4RR. Further, the VDC brake hydraulic pressure unit 2 reduces the hydraulic pressure of each wheel cylinder 4FL, 4FR, 4RL, 4RR and suppresses the lock when slip occurs in each wheel FLW, FRW, RLW, RRW during braking. Also, so-called ABS (Antilock Brake System) control can be executed.

[Regenerative braking device]
The traveling electric motor 5 is provided as a traveling drive source for the left and right front wheels (drive wheels) FLW and FRW, and has a drive motor function and a power generator function. The electric motor 5 for traveling transmits driving force to the left and right front wheels (drive wheels) FLW and FRW by driving the motor while sucking and consuming battery power during power running. During regeneration, the load is applied to the rotational drive of the left and right front wheels to convert it into electrical energy, and the battery 30 is charged with the generated power. That is, the load applied to the rotational driving of the left and right front wheels (drive wheels) FLW and FRW is the regenerative braking torque.
Therefore, the regenerative braking device 50 is constituted by the electric motor 5 for traveling and the motor controller 103 shown in FIG. 2 for controlling the regenerative braking torque. The traveling electric motor 5 is controlled by applying a three-phase alternating current generated by the inverter 104 based on a control command from the motor controller 103.

[Control system]
The braking torque control system of the braking control apparatus according to the first embodiment includes the integrated controller 100, the brake controller 101, and the motor controller 103 shown in FIG.

The integrated controller 100 performs EV system start and stop control, driving force calculation and motor output command, deceleration force calculation, motor / brake output command, EV system diagnosis, fail-safe function, and the like.
Further, the integrated controller 100 integrates and controls the brake controller 101 and the motor controller 103 so as to obtain the driver requested braking torque at the time of regenerative cooperative brake control or the like. The integrated controller 100 includes battery charge capacity information from the battery controller 102, vehicle speed information from the wheel speed sensor 92, braking operation information from the brake switch 93, pedal stroke information for the brake pedal 15 from the pedal stroke sensor 94, master Master cylinder hydraulic pressure information from the cylinder hydraulic pressure sensor 16 is input. As the wheel speed sensor 92, a wheel speed rotation number sensor capable of detecting a vehicle speed up to an extremely low vehicle speed range is used. And real deceleration is calculated | required by carrying out time differentiation calculation processing of the wheel speed rotation speed.

  The brake controller 101 inputs a signal from the integrated controller 100 and pressure information from the master cylinder hydraulic pressure sensor 16 of the VDC brake hydraulic pressure unit 2. And according to a predetermined control law, while outputting a drive command with respect to VDC motor 21 of VDC brake hydraulic unit 2 and solenoid valves 25, 26, 27, and 28 shown in Drawing 3 mentioned below, an integrated controller For 100, the target value of the regenerative cooperative braking torque is output.

  The motor controller 103 is connected via an inverter 104 to the traveling electric motor 5 connected to the left and right front wheels FLW and FRW as drive wheels (see FIG. 1). When a regenerative command is input from the integrated controller 100 during brake control, the regenerative braking torque generated by the traveling electric motor 5 is controlled according to the input regenerative command. The motor controller 103 also has a function of controlling the motor torque and the motor rotation speed generated by the traveling electric motor 5 according to the traveling state and the vehicle state during traveling.

  Note that an inverter 104 and a charger 106 are connected to the battery 30 via a DC / DC junction box 105. In addition, a charging port 106 a is connected to the charger 106.

  The sensor group 90 includes the master cylinder hydraulic pressure sensor 16, the wheel speed sensor 92, the brake switch 93, the pedal stroke sensor 94, the accelerator pedal switch 95, the yaw rate / lateral / front / rear G sensor 96, the steering angle sensor 97, and the like. Is provided. The controllers 100 to 103 are connected to each other via a CAN communication line 100c so that they can communicate with each other. Although the sensor group 90 is illustrated as being directly connected to the integrated controller 100 in the figure, each sensor of the sensor group 90 is connected to the integrated controller 100 via the CAN communication line 100c and the controllers 101 to 103. The one connected to is also included.

[VDC brake hydraulic unit configuration]
FIG. 3 is a brake hydraulic circuit diagram showing the VDC brake hydraulic unit 2. The VDC brake hydraulic unit 2 has a well-known configuration and will be described briefly.

  The VDC brake fluid pressure unit 2 controls the wheel cylinder fluid pressure PW / CYL based on a command from the brake controller 101 (see FIG. 2). The VDC brake fluid pressure unit 2 includes a VDC motor 21, fluid pressure pumps 22 and 22 driven by the VDC motor 21, low pressure reservoirs 23 and 23, and a master cylinder fluid pressure sensor 16. The VDC brake hydraulic pressure unit 2 includes, as solenoid valves, a first M / C cut solenoid valve 25, a second M / C cut solenoid valve 26, holding solenoid valves 27, 27, 27, 27, and a pressure reducing solenoid. And valves 28, 28, 28, 28.

  The first M / C cut solenoid valve 25 and the second M / C cut solenoid valve 26 are normally open solenoid valves that are closed during driving. When the VDC motor 21 is driving the pump, the primary hydraulic pipe 61 and the secondary hydraulic pipe 62 are connected. Shut off and control the differential pressure (= pump-up hydraulic pressure) between the wheel cylinder hydraulic pressure PW / CYL (downstream pressure) and the master cylinder hydraulic pressure PM / CYL (upstream pressure). Both cut valves 25, 26 are provided with check valves 25a, 26a that allow the brake fluid to return from the wheel cylinders 4FL, 4FR, 4RL, 4RR to the master cylinder 13 when the valves are closed.

  The holding solenoid valves 27, 27, 27, 27 (IN valves) are normally open solenoid valves that are closed when driven, and the wheel cylinder hydraulic pressure to each of the wheel cylinders 4FL, 4FR, 4RL, 4RR by closing. Hold PW / CYL.

  The pressure-reducing solenoid valves 28, 28, 28, 28 (OUT valves) are normally closed solenoid valves that are opened during driving, and the wheel cylinder hydraulic pressures to the wheel cylinders 4FL, 4FR, 4RL, 4RR are opened by opening the valves. PW / CYL is released to the low-pressure reservoir 23 and decompressed.

  Thus, by independently controlling the open / closed states of the holding solenoid valve 27 and the pressure reducing solenoid valve 28, the wheel cylinder hydraulic pressure PW / CYL to each wheel cylinder 4FL, 4FR, 4RL, 4RR is independently controlled for each wheel. . Thereby, the VDC brake hydraulic unit 2 performs so-called VDC control, TCS control, ABS control, regenerative cooperative brake control, front and rear wheel braking torque distribution control, and the like.

  FIG. 3 shows a state when the wheel cylinders 4FL, 4FR, 4RL, and 4RR are pressurized, and the valves 25, 26, 27, and 28 are in an inoperative state. At the time of this pressure increase, the master cylinder hydraulic pressure PM / CYL and / or the pump pressure can be supplied to each wheel cylinder 4FL, 4FR, 4RL, 4RR to increase the pressure. When the pressure is increased by the pump pressure, both cut solenoid valves 25 and 26 are closed.

  Further, when the wheel cylinder hydraulic pressure PW / CYL is held in each wheel cylinder 4FL, 4FR, 4RL, 4RR, the holding solenoid valve 27 connected to each wheel cylinder 4FL, 4FR, 4RL, 4RR to be held is energized. Close the valve. In this case, the wheel cylinder hydraulic pressure PW / CYL is confined between the holding solenoid valve 27 and the pressure reducing solenoid valve 28 in the closed state, and the wheel cylinder hydraulic pressure PW / CYL is held.

  Further, when the wheel cylinder hydraulic pressure PW / CYL is reduced in each wheel cylinder 4FL, 4FR, 4RL, 4RR, the holding solenoid valve 27 connected to each wheel cylinder 4FL, 4FR, 4RL, 4RR to be reduced is energized. The valve is closed and the pressure reducing solenoid valve 28 is energized to open. In this case, the wheel cylinder hydraulic pressure PW / CYL is cut off from the master cylinder 13 side by the closed holding solenoid valve 27 and communicated to the low pressure reservoir 23 side through the valve opening pressure reducing solenoid valve 28. The pressure is reduced.

  By independently controlling the pressure increase, holding, and pressure reduction on each wheel, the wheel cylinder hydraulic pressure PW / CYL to each wheel cylinder 4FL, 4FR, 4RL, 4RR is independent for each wheel as described above. Can be controlled.

  Further, as described in Patent Document 1, the low-pressure reservoir 23 is provided with a push rod 23b that can push up the check ball 23a when the amount of stored brake fluid is less than a predetermined value. ing. Therefore, when the hydraulic pump 22 is driven in a state where no brake fluid is stored in the low pressure reservoir 23, the hydraulic pump 22 is connected to the master cylinder 13 via the hydraulic pipes 61 and 62 and the return circuits 67 and 67. Brake fluid can be inhaled.

[Master cylinder configuration]
Here, the configuration of the master cylinder 13 will be described.
The master cylinder 13 communicates with the reservoir 14 via the reservoir port 13a shown in FIG. Therefore, when the brake pedal 15 is depressed, the primary piston 13b linked to the stroke strokes to the back side of the master cylinder 13 and the reservoir port 13a is blocked. PM / CYL is set up. Therefore, the limiting means is configured based on the arrangement of the master cylinder 13 and the reservoir port 13a.

  In FIG. 4, the position of the primary piston 13 b indicated by the solid line is the initial position ST <b> 0 when the braking operation of the brake pedal 15 is started. On the other hand, the position of the primary piston 13b indicated by a two-dot chain line in FIG. 4 is a suppression range setting position STlim that completely closes the reservoir port 13a.

Therefore, in the first embodiment, when the brake pedal 15 is depressed, the pedal stroke (= piston stroke) is limited to the generation of the master cylinder hydraulic pressure PM / CYL from the initial position ST0 to the suppression range setting position STlim (this embodiment). In the first form, the number is limited to 0). Hereinafter, a region where the generation of the master cylinder hydraulic pressure PM / CYL from the initial position ST0 to the suppression range setting position STlim is limited is referred to as a hydraulic pressure generation suppression region LT.
Further, as shown in the braking torque characteristic diagram of FIG. 5, the master cylinder hydraulic pressure PM / CYL from the time when the pedal stroke (= piston stroke) exceeds the suppression range setting position STlim and enters the non-hydraulic pressure generation suppression region. Stand up. The generation suppression of the master cylinder hydraulic pressure PM / CYL can be remarkably performed when the pedal stroke speed is relatively low and the brake fluid flows in the reservoir port 13a. On the other hand, when the pedal stroke speed becomes relatively high, the fluid flow in the reservoir port 13a is limited, and the above-described suppression of the generation of hydraulic pressure is suppressed, so that the master cylinder hydraulic pressure PM / CYL is reduced even in the hydraulic pressure generation suppression region LT. It may occur.

  The integrated controller 100, the brake controller 101, and the motor controller 103 execute control for generating a braking torque in accordance with the driver requested braking torque. This control will be described below.

[Driver demand braking torque control]
FIG. 7 shows a flow of driver-requested braking torque control executed by the integrated controller 100, the brake controller 101, and the motor controller 103 in the brake control device of the first embodiment. This process is started when a brake operation start is input from the brake switch 93.

In step S1, the stroke signal from the pedal stroke sensor 94 and the master cylinder hydraulic pressure PM / CYL from the master cylinder hydraulic pressure sensor 16 are read, and the driver requested braking torque is obtained based on this.
In step S2, based on battery information such as battery charge capacity (battery SOC (abbreviation of “State Of Charge”)) based on the battery voltage and battery temperature from the battery controller 102, and vehicle speed information from the wheel speed sensor 92, It is determined whether or not regenerative braking is possible. If regenerative braking is possible, the process proceeds to step S3. If regenerative braking is not possible, the process proceeds to step S6. When regenerative braking is impossible, for example, when the battery SOC is in a fully charged state exceeding the upper limit value, when the battery temperature is higher than a preset upper limit temperature, or when the vehicle speed is lower than the set vehicle speed range Is low or high.

In step S3 which proceeds when it is determined in step S2 that regenerative braking is possible, the target regenerative braking torque is calculated based on the vehicle speed or the like, and then the process proceeds to step S4.
In step S4, the pump-up braking torque necessary for obtaining the driver required braking torque obtained in step S1 is obtained, and then the process proceeds to step S5. Here, the pump-up braking torque is a value obtained by subtracting the target regenerative braking torque and the braking torque obtained by the master cylinder hydraulic pressure PM / CYL actually generated by the braking operation from the driver requested braking torque.
In step S5, a target regenerative braking torque is generated by regenerative power generation of the traveling electric motor 5 based on the control of the motor controller 103, and a target pump-up braking torque is generated by the VDC brake hydraulic unit 2 if necessary, Go to the end.

  On the other hand, in step S6 which proceeds when it is determined in step S2 that regeneration is impossible (NO), the pump-up braking torque is calculated, and then the process proceeds to step S7. In this step S6, the pump-up braking torque is a value obtained by subtracting the braking torque obtained from the master cylinder hydraulic pressure PM / CYL as the operation-corresponding braking torque from the driver requested braking torque.

The above-described pump-up braking torque, regenerative braking torque, and total braking torque based on the hydraulic braking torque based on the master cylinder hydraulic pressure PM / CYL have the characteristics shown in FIG.
In the hydraulic pressure generation suppression region LT until the pedal stroke reaches the suppression range setting position STlim and the reservoir port 13a is closed, the total braking torque is based on the friction braking torque generated by the regenerative braking torque and the pump-up braking torque. Secure. In this case, the regenerative braking torque and the friction braking torque due to pump-up braking generate an amount corresponding to the operation-corresponding braking torque (driver required braking torque) corresponding to the pedal stroke of the brake pedal 15.
Thereafter, when the master cylinder hydraulic pressure PM / CYL rises, the operation-corresponding braking torque by the master cylinder hydraulic pressure PM / CYL is added to the base braking torque so far.

  In addition, when the vehicle speed decreases due to braking operation, it becomes difficult to obtain regenerative braking torque.With the base braking torque, when the vehicle speed falls below the set vehicle speed with the lapse of time from the start of braking operation, the regenerative braking torque is distributed. While decreasing, the braking torque is replaced to increase the friction braking torque distribution by the pump-up braking torque.

The replacement of the braking torque described above is performed not only when the vehicle speed is equal to or lower than the set vehicle speed as described above, but also when the slip ratio of the drive wheels (the left and right front wheels FLW and FRW) exceeds the slip threshold SLPlim.
The flow of the braking torque replacement control process in this case will be described based on the flowchart of FIG. Note that the braking torque replacement control based on the slip ratio in FIG. 8 is started in response to the execution of the regenerative braking / pump-up braking in step S5 described above.
In step S101, it is determined whether or not the master cylinder hydraulic pressure PM / CYL is generated. If so, the process proceeds to step S102, and if not, the process proceeds to step S103.

  In step S102 that proceeds when the master cylinder hydraulic pressure PM / CYL is generated, the slip threshold SLPlim is set to have a relatively large difference (slip rate) from the vehicle speed (driven wheel speed) as shown in FIG. After setting to the set first threshold value Slim1, the process proceeds to step S104. On the other hand, in step S103 that proceeds when the master cylinder hydraulic pressure PM / CYL is not generated, the slip rate is relatively set to the difference (slip rate) from the vehicle speed (driven wheel speed) as shown in FIG. After setting the second threshold value Slim2 to be smaller, the process proceeds to step S104.

In step S104, the slip ratio WSslip of the drive wheels (left and right front wheels FLW, FRW) is calculated, and it is determined whether or not the slip threshold SLPlim has been exceeded. If not, the process proceeds to step S106.
In step S105, which proceeds when the slip ratio WSslip of the drive wheels (the left and right front wheels FLW, FRW) exceeds the slip threshold SLPlim, the switching operation is started, and then the operation proceeds to the end. On the other hand, in step S106 that proceeds when the slip ratio WSslip of the drive wheels (left and right front wheels FLW, FRW) does not exceed the slip threshold, regenerative braking is continued and the process proceeds to the end.
When the slip ratio WSslip exceeds the slip threshold SLPlim, the brake controller 101 starts a well-known ABS control at the same time.

(Operation of Embodiment 1)
Next, an example of operation of the braking control device of the first embodiment and the comparative example will be described based on a time chart. Prior to the description, response of hydraulic braking will be described.

  As described above, the hydraulic braking device 1 includes the master cylinder hydraulic pressure generating device 10 and the VDC brake hydraulic pressure unit 2. At the time of braking operation, if the stroke amount of the brake pedal 15 is equal to or greater than the suppression range setting position STlim, the master cylinder hydraulic pressure PM / CYL is generated in the master cylinder hydraulic pressure generator 10, but the stroke amount is set in the suppression range. Below the position STlim, the master cylinder hydraulic pressure PM / CYL is not generated.

  When the VDC brake hydraulic pressure unit 2 is driven to raise the brake hydraulic pressure from the state where the master cylinder hydraulic pressure PM / CYL is not generated, the hydraulic pump 22 includes the return circuit 67 and the low pressure reservoir 23. The brake fluid in the master cylinder 13 and the reservoir 14 is sucked in via In this case, since the master cylinder hydraulic pressure has not risen, it takes time for the brake hydraulic pressure to rise.

On the other hand, when the VDC brake hydraulic pressure unit 2 is driven and the brake hydraulic pressure is raised while the master cylinder hydraulic pressure PM / CYL is generated, the hydraulic pump 22 similarly includes the return circuit 67 and the low pressure reservoir 23. The brake fluid in the master cylinder 13 is sucked in via In this case, since the brake hydraulic pressure is already raised from the state where the master cylinder hydraulic pressure PM / CYL is increased, the responsiveness is high.
As described above, depending on whether or not the master cylinder hydraulic pressure PM / CYL is generated in the master cylinder hydraulic pressure generation device 10, a difference occurs in the response speed of the increase in the brake hydraulic pressure (friction braking torque) at the time of replacement.

Next, an operation example of the comparative example and its problems based on the difference in the rising speed of the friction braking torque depending on whether or not the master cylinder hydraulic pressure PM / CYL is generated will be described.
FIGS. 9 and 10 show an example in which the slip control exceeding the slip threshold SLPlim occurs on the drive wheels (left and right front wheels FLW, FRW) during braking and the substitution control and the ABS control are executed. In both figures, the upper part of the braking torque is represented as positive (minus as driving torque).

First, an operation example of FIG. 9 will be described.
In this example, as the slip threshold value SLPlim, a value (a value obtained by relatively increasing the difference from the driven wheel speed) corresponding to the case where the rising response when the master cylinder hydraulic pressure PM / CYL is generated is high. Used.
In the example of FIG. 9, at the time of t01 during braking, slip occurs in the driving wheels (left and right front wheels FLW, FRW), and the driving wheel speed is lower than the driven wheel speed corresponding to the vehicle body speed as shown in the figure. doing.
Then, at time t02 when the wheel speed difference between the driving wheel speed and the driven wheel speed (driving wheel slip) exceeds the set slip threshold SLPlim, switching between the regenerative braking torque and the friction braking torque is executed. Further, from this time (t02), the friction braking torque is reduced according to the slip state based on the ABS control, and the driving wheel speed is controlled toward the driven wheel side.

At this time, when the master cylinder hydraulic pressure PM / CYL is not generated in the master cylinder hydraulic pressure generation device 10 and the hydraulic pressure responsiveness is low, the rising gradient of the friction braking torque becomes gradual, and the regeneration is correspondingly increased. The decreasing gradient of the braking torque also becomes gentle, and it takes time to replace.
Therefore, the pressure reducing operation timing by the ABS control is also delayed, and the time (slip recovery time) required until the driving wheel speed recovers to the driven wheel speed (t03) becomes long.

On the other hand, FIG. 10 shows a value (corresponding to the difference from the driven wheel speed relative to the case where the hydraulic pressure responsiveness where the master cylinder hydraulic pressure PM / CYL is not generated is low as the slip threshold SLPlim. The smaller value is used.
In this case, even if the replacement is performed in a state where the master cylinder hydraulic pressure PM / CYL is not generated, the replacement start timing itself is advanced, so that the time required for the replacement can be shortened.

FIG. 10 shows a case where the slip threshold value SLPlim is used and the master cylinder hydraulic pressure PM / CYL is generated (high responsiveness). In this case, slip occurs in the drive wheels (left and right front wheels FLW, FRW) at time t011, and replacement is started at time t012, and the drive wheel speed returns to the driven wheel speed at time t013 (slip recovery is achieved). ing).
In this case, since the hydraulic pressure responsiveness is high, the replacement can be performed in a shorter time, and the recovery timing of the drive wheel slip can be advanced. However, since the start timing of the switching control (at time point t012) becomes earlier and the decreasing gradient of the regenerative braking torque is steep, the recovery efficiency of regenerative energy deteriorates.

(Operation of Embodiment 1)
(When master cylinder hydraulic pressure PM / CYL is generated)
In the braking control apparatus of the first embodiment, as indicated by a two-dot chain line in FIG. 4, the primary piston 13b is stepped on from the position of the reservoir port 13a, and the master cylinder hydraulic pressure PM / CYL is generated (hydraulic pressure The operation with high responsiveness will be described with reference to FIG.

When the master cylinder hydraulic pressure PM / CYL is generated as described above, the difference from the driven wheel speed is relatively large as the slip threshold value SLPlim by the processing of steps S101 → S102 based on the flowchart of FIG. One threshold value Slim1 is set.
Further, when the master cylinder hydraulic pressure PM / CYL is rising as described above, the VDC brake hydraulic pressure unit 2 sucks the brake fluid of the master cylinder 13 through the return circuit 67 and the low pressure reservoir 23 as described above. . Therefore, the hydraulic pressure increase response is relatively high.

Therefore, similarly to the comparative example, when the drive wheel slip occurs from time t11 and the drive wheel speed falls below the slip threshold (first threshold Slim1), the replacement control is started. In this case, since the responsiveness is high as described above, the rising speed (increase gradient) of the friction braking torque can be increased, and the regenerative braking torque can be decreased with a steep gradient accordingly.
Therefore, even if the first threshold value Slim1 having a large difference from the driven wheel speed is used as the slip threshold value, the switching between the regenerative braking torque and the friction braking torque can be executed in a short time. For this reason, the recovery timing t13 of the drive wheel slip by ABS control can also be made earlier than the example shown in FIG.

  Therefore, the start timing of the replacement control can be relatively delayed, and the recovery amount of the regenerative braking torque can be relatively increased. In addition, as shown in FIG. 12, the timing shown as t22 in FIG. 11 is the start timing of the replacement control when the second threshold value Slim2 is used as the slip threshold value SLPlim. As described above, in the example of FIG. 11, the recovery amount of regenerative energy can be increased as described above by setting the start timing of the switching control to the timing t12 later than t22.

(When master cylinder hydraulic pressure PM / CYL is not generated)
Next, the operation when the master cylinder hydraulic pressure PM / CYL is not generated and the hydraulic pressure response is relatively low will be described with reference to FIG.

  When the master cylinder hydraulic pressure PM / CYL is not generated as described above, the difference (slip amount) from the driven wheel speed is relatively determined as the slip threshold SLPlim by the processing of steps S101 → S103 based on the flowchart of FIG. Therefore, the second threshold value Slim2 is set to be small.

In this case, the drive wheel slip has occurred from the time t21, but the replacement control is started at the time t22 earlier than the example shown in FIG.
Therefore, the hydraulic pressure responsiveness is low, and the end timing of the replacement control can be made earlier than that of the comparative example even if the braking hydraulic pressure is increased with the same rising gradient as that of the comparative example shown in FIG. As a result, the drive wheel slip recovery timing (t23) by the ABS control can also be set to the same timing as when the master cylinder hydraulic pressure PM / CYL having a high hydraulic pressure response shown in FIG. 11 is generated. As described above, when the master cylinder hydraulic pressure PM / CYL is not generated and the hydraulic pressure responsiveness is low, priority is given to the recovery timing of the drive wheel slip, and vehicle stability can be ensured.

Next, the effect of Embodiment 1 is demonstrated.
In the braking control device of the first embodiment, the effects listed below can be obtained.
1) The braking control device of the first embodiment is
A regenerative braking device 50 for controlling regenerative braking torque applied to drive wheels (left and right front wheels FLW, FRW) of the vehicle;
Limiting means (reservoir port 13a and reservoir port 13a) that generates the master cylinder hydraulic pressure PM / CYL in accordance with the braking operation of the driver in the vehicle and limits the generation of the master cylinder hydraulic pressure PM / CYL according to the braking operation at the initial stage of the braking operation. As a brake fluid supply path between the master cylinder hydraulic pressure generating device 10 having the primary piston 13b) and the wheel cylinders 4FL, 4FR, 4RL, 4RR that generate the friction braking torque at the master cylinder 13 and the wheels. A hydraulic braking device 1 having a VDC brake hydraulic unit 2 as a brake actuator capable of increasing and decreasing the wheel cylinder hydraulic pressure PW / CYL by supplying and discharging brake fluid to and from each of the hydraulic pipes 63 to 66;
A driver request braking torque detection unit (a portion that executes the process of step S1) that detects a driver request braking torque during a braking operation;
A drive wheel slip detector for detecting slip of the drive wheels (left and right front wheels FLW, FRW) (a portion for calculating the slip ratio WSslip in step S104);
An integrated controller as a braking torque control unit that controls the regenerative braking device 50 and the VDC brake hydraulic pressure unit 2 during braking operation and performs regenerative cooperative braking control that generates a driver-requested braking torque based on the regenerative braking torque and the friction braking torque. 100, brake controller 101, motor controller 103,
Included in the integrated controller 100, when the driving wheel slip exceeds a preset slip threshold SLPlim during regenerative cooperative braking control, the VDC brake hydraulic pressure unit 2 increases friction braking torque while reducing the regenerative braking torque. A switching control unit (a part for executing the flowchart of FIG. 8) for executing control;
Included in the switching control unit, the slip threshold SLPlim is set to a relatively small slip amount when braking by the limiting means during braking operation, and the slip threshold SLPlim is relatively slipped when the limiting means is not limited. A threshold value setting unit (a portion for executing the processing of steps S101 to S103) for setting the amount to a large value;
It is characterized by having.
Therefore, during the braking operation, the limiting means limits the increase in the master cylinder hydraulic pressure PM / CYL (in the first embodiment, the master cylinder hydraulic pressure PM / CYL = 0), and the control response by the VDC brake hydraulic pressure unit 2 Is low, a relatively small value is used as the slip threshold SLPlim.
Thereby, the start timing of the replacement control due to the drive wheel slip exceeding the slip threshold SLPlim is earlier than the case where a relatively large value is used as the slip threshold SLPlim. Therefore, even if the pressure increase response by the VDC brake fluid pressure unit 2 is low, replacement can be performed in a short time. Therefore, the ABS control by the VDC brake hydraulic unit 2 is also performed at an early stage, and the drive wheel slip can be recovered early.
On the other hand, when the braking operation is not performed, the limiting means does not limit the increase in the master cylinder hydraulic pressure PM / CYL, the master cylinder hydraulic pressure PM / CYL is generated, and the control response by the VDC brake hydraulic pressure unit 2 is high. Uses a relatively large value as the slip threshold SLPlim.
Thereby, the start timing of the replacement control due to the drive wheel slip exceeding the slip threshold value SLPlim is slower than the case where a relatively small value is used as the slip threshold value SLPlim, and the recovery amount of regenerative energy is increased. Can do. Further, since the control response by the VDC brake hydraulic pressure unit 2 is high, the regenerative braking torque can be decreased and the friction braking torque can be increased with a steep slope, and the time required for replacement can be shortened. Thereby, it is possible to recover from the drive wheel slip in a short time.
Therefore, it is possible to improve the energy recovery efficiency by regeneration by delaying the start timing of the switching control while achieving early recovery of the drive wheel slip.

2) The braking control device of the first embodiment is
The limiting means connects the primary piston 13b that strokes in conjunction with the depression of the brake pedal 15 as a braking operation, the master cylinder 13 and the reservoir 14, and connects the initial position ST0 of the primary piston 13b via the hydraulic pressure generation suppression region LT. And the reservoir port 13a is disposed, and the primary cylinder 13b strokes the fluid pressure generation suppression region LT and the master cylinder 13 communicates with the reservoir 14 via the reservoir port 13a. Is a means to limit the occurrence of / CYL,
In the determination of the restricted state and the unrestricted state, the threshold setting unit determines whether the position of the primary piston 13b is a position where the master cylinder 13 and the reservoir 14 are communicated via the reservoir port 13a, or a position where both the 13, 14 are shut off. Based on the above, it is determined that the blocking position is an unrestricted state, and the communicating position is determined to be a restricted state.
That is, in the state where the master cylinder hydraulic pressure PM / CYL is generated, the VDC brake hydraulic pressure unit 2 is equivalent to the generation of the master cylinder hydraulic pressure PM / CYL compared to when the master cylinder hydraulic pressure PM / CYL is not generated. Increased pressure response due to.
Therefore, it is possible to determine the restricted state and the unrestricted state of the restricting means based on the positional relationship between the reservoir port 13a serving as the restricting means and the primary piston 13b.

3) The braking control device of the first embodiment is
The threshold value setting unit (the part that executes the processes of steps S101 to S103) determines the piston position in the determination of the restricted state and the non-restricted state based on the output of the master cylinder hydraulic pressure sensor 16 that detects the master cylinder hydraulic pressure PM / CYL. Based on the above, when the master cylinder hydraulic pressure is not generated, the communication position is set, and when the master cylinder hydraulic pressure is generated, the cutoff position is set.
Therefore, the positional relationship between the reservoir port 13a and the primary piston 13b can be easily detected by the existing master cylinder hydraulic pressure sensor 16.
In addition, when the brake pedal 15 is depressed quickly, the master cylinder hydraulic pressure PM / CYL pressure may be generated due to the orifice effect of the reservoir port 13a regardless of the primary piston 13b in the hydraulic pressure generation suppression region LT. . That is, depending on the braking operation speed of the brake pedal 15, the restricting means may be in an unrestricted state even if the reservoir port 13a is not shut off. In such a case, the control responsiveness of the VDC brake hydraulic unit 2 becomes relatively high due to the generation of the master cylinder hydraulic pressure PM / CYL pressure.
In this way, by using the master cylinder hydraulic pressure PM / CYL detected by the master cylinder hydraulic pressure sensor 16 for the determination of the restricted state and the non-restricted state by the restricting means, it becomes possible to more accurately determine the restricted state. .
If the primary piston 13b is in the restricted state due to the orifice effect even if the position of the primary piston 13b is in the hydraulic pressure suppression region LT as described above, the replacement timing is delayed using the first threshold value Slim1, and the amount of recovered regenerative energy is increased. Can be increased.

4) The braking control device of the first embodiment is
The hydraulic braking device 1 includes a pressure reducing solenoid valve 28 as pressure reducing means capable of reducing the wheel cylinder hydraulic pressure PW / CYL.
The brake controller 101 as a braking torque control unit performs slip recovery control for reducing the drive wheel slip by reducing the wheel cylinder hydraulic pressure PW / CYL by operating the pressure-reducing solenoid valve 28 at the time of replacement control due to the occurrence of drive wheel slip. The ABS control is executed.
Therefore, when drive wheel slip occurs, switching control is executed, switching from regenerative braking torque to friction braking torque is executed, and ABS control for reducing the wheel cylinder hydraulic pressure PW / CYL increased by this switching is executed. . Thereby, drive wheel slip can be efficiently recovered.

(Other embodiments)
Next, a power conversion device according to another embodiment will be described.
Since the other embodiment is a modification of the first embodiment, the same reference numerals as those in the first embodiment are assigned to the same components as those in the first embodiment, and the description thereof is omitted. Only the differences will be described.

(Embodiment 2)
Next, the braking control device of Embodiment 2 will be described.
The second embodiment is an example in which the determination of the restricted state and the unrestricted state of the restricting means is detected based on the output of the pedal stroke sensor 94 that detects the stroke amount of the brake pedal 15.
That is, in the flowchart shown in FIG. 13, in step S201, it is determined whether or not the stroke amount Str of the brake pedal 15 exceeds the suppression range setting position STlim. If it exceeds, the process proceeds to step S102. Proceed to
Other processes are the same as those in the first embodiment, and thus the description thereof is omitted.

2-1) The braking control device of the second embodiment is
The threshold setting unit (the part that executes the processing of steps S101 to S103) determines the position of the primary piston 13b in the determination of the restricted state and the non-restricted state based on the output of the pedal stroke sensor 94 that detects the stroke amount of the brake pedal 15. It detects based on.
Therefore, the positional relationship between the reservoir port 13a and the primary piston 13b of 2) can be easily detected by the existing pedal stroke sensor 94.

(Embodiment 3)
Next, the braking control device of Embodiment 3 will be described.
In the third embodiment, the torque change gradients of the regenerative braking torque and the friction braking torque during the switching control are set relatively abruptly as the master cylinder hydraulic pressure PM / CYL is larger when the switching control is executed. It is an example.
In the third embodiment, in the flowchart shown in FIG. 14, the processing content in step S305, which is advanced when the slip ratio WSslip of the drive wheels (the left and right front wheels FLW, FRW) exceeds the slip threshold SLPlim, is different from that in the first embodiment. .
That is, in step S305, switching between regenerative braking torque and friction braking torque is performed. In this case, the larger the master cylinder hydraulic pressure PM / CYL, the more the regenerative braking torque and the torque change gradient of the friction braking torque are relative. Set suddenly.

3-1) In the braking control device of the first embodiment,
In step S305 of the switching control unit (the portion that executes the process of the flowchart of FIG. 14), the larger the master cylinder hydraulic pressure PM / CYL, the more the regenerative braking torque and the torque change gradient of the friction braking torque during the switching control are relative. It is characterized by being set suddenly.
That is, the greater the master cylinder hydraulic pressure PM / CYL, the faster the response speed due to pump-up. For this reason, the time required for replacement can be shortened by setting the torque change gradient at the time of replacement suddenly.
In this case, at the same time, in setting the first threshold value Slim1 in step S102, the first threshold value Slim1 is proportional to the master cylinder hydraulic pressure PM / CYL. It is preferable to set a large difference from the vehicle speed.
As a result, it is possible to increase the recovery amount of regenerative energy while further delaying the start timing of the switching control and suppressing the drive wheel slip.

  As described above, the braking control device of the present invention has been described based on the embodiment. However, the specific configuration is not limited to the embodiment, and the gist of the invention according to each claim of the claims. As long as they do not deviate, design changes and additions are permitted.

  For example, in the embodiment, an example in which the braking control device of the present invention is applied to a front-wheel drive electric vehicle has been described. However, the braking control device of the present invention can be applied to a rear wheel drive, all-wheel drive electric vehicle, a hybrid vehicle, and a fuel cell vehicle as long as the vehicle switches between regenerative braking torque and friction braking torque. .

In the embodiment, the limiting means of the master cylinder hydraulic pressure generating device is limited based on the positional relationship between the reservoir port and the primary piston, but is not limited thereto. For example, in an electric booster, even if an input member strokes due to depression of a brake pedal, the electric assist member does not move until the stroke amount exceeds a predetermined amount, and the stroke amount exceeds a predetermined amount. It is possible to use the one that generates the master cylinder hydraulic pressure by moving the assist member.
Further, in the embodiment, the generation of the master cylinder hydraulic pressure is limited to 0 when the restriction is restricted, but the increase in the master cylinder hydraulic pressure is suppressed at the time of restriction, compared with the non-restricted case. You may use what generate | occur | produces.
In the embodiment, the VDC brake hydraulic unit is shown as the brake actuator, but the present invention is not limited to this. For example, the pressure may be increased by a booster operation that drives the electric assist member of the electric booster.

1 Hydraulic braking device 2 VDC brake hydraulic unit (brake actuator)
4FL Left front wheel wheel cylinder 4FR Right front wheel wheel cylinder 4RL Left rear wheel wheel cylinder 4RR Right rear wheel wheel cylinder 10 Master cylinder hydraulic pressure generator 13 Master cylinder 13a Reservoir port (limitation means)
13b Primary piston (limitation means)
14 Reservoir 15 Brake pedal 16 Master cylinder hydraulic pressure sensor 50 Regenerative braking device 94 Pedal stroke sensor (driver required braking torque detection unit)
100 integrated controller (braking torque control unit: replacement control unit: threshold setting unit)
101 Brake controller (braking torque controller)
103 Motor controller (braking torque controller)
FLW Front left wheel (drive wheel)
FRW Right front wheel (drive wheel)
PM / CYL Master cylinder hydraulic pressure PW / CYL Wheel cylinder hydraulic pressure

Claims (6)

A regenerative braking device for controlling a regenerative braking torque applied to drive wheels of the vehicle;
A master cylinder hydraulic pressure generating device including a limiting means for forming a master cylinder hydraulic pressure in accordance with a braking operation of a driver in the vehicle and limiting the generation of the master cylinder hydraulic pressure according to the braking operation at an early stage of the braking operation; And a hydraulic braking device comprising a brake actuator capable of increasing and decreasing the wheel cylinder hydraulic pressure by supplying and discharging the brake fluid to and from the brake fluid supply path between the master cylinder and the wheel cylinder that generates friction braking torque at the wheel When,
A driver-requested braking torque detector for detecting a driver-requested braking torque during the braking operation;
A drive wheel slip detector for detecting slip of the drive wheel;
A braking torque control unit that controls the regenerative braking device and the brake actuator during the braking operation, and performs regenerative cooperative braking control that generates the driver-requested braking torque by the regenerative braking torque and the friction braking torque;
Included in the braking torque control unit, when the driving wheel slip exceeds a preset slip threshold during the regenerative cooperative braking control, the friction braking torque is increased by the brake actuator while decreasing the regenerative braking torque. A switching control unit for executing switching control;
Included in the replacement control unit, during the braking operation, when limiting by the limiting means, the slip threshold is set to a relatively small slip amount, and when the limiting means is not limited, the slip threshold is set, A threshold setting unit for setting the slip amount to a relatively large value;
A braking control device comprising: The braking control device according to claim 1, wherein
The limiting means connects a piston that strokes in conjunction with depression of a brake pedal as the braking operation, the master cylinder, and a reservoir, and a reservoir that is disposed from an initial position of the piston via a hydraulic pressure generation suppression region And a means for restricting the generation of the master cylinder hydraulic pressure while the piston strokes the hydraulic pressure generation suppression region and the master cylinder communicates with the master cylinder via the reservoir port. Yes,
In the determination of the restricted state and the non-restricted state, the threshold setting unit determines whether the position of the piston is a position where the master cylinder and the reservoir communicate with each other via the reservoir port, or a position where both are blocked. Based on this, the braking control device is characterized in that the non-restricted state is determined at the blocking position and the limited state is determined at the communicating position. The braking control device according to claim 2, wherein
The braking control device according to claim 1, wherein the threshold value setting unit detects the piston position in the determination between the restricted state and the non-restricted state based on an output of a pedal stroke sensor that detects a stroke amount of the brake pedal. The braking control device according to claim 2, wherein
The threshold value setting unit determines whether the piston position in the determination of the restricted state and the non-restricted state is based on an output of a master cylinder hydraulic pressure sensor that detects the master cylinder hydraulic pressure. The braking control device according to claim 1, wherein the brake control device is in the communication position and is in the shut-off position when the master cylinder hydraulic pressure is generated. The braking control device according to claim 4, wherein
The braking control device, wherein the switching control unit sets a gradient of the regenerative braking torque and the friction braking torque at the time of switching control relatively steeply as the master cylinder hydraulic pressure increases. In the braking control device according to any one of claims 1 to 5,
The hydraulic braking device includes a decompression means capable of reducing the wheel cylinder hydraulic pressure,
The braking torque control unit performs slip recovery control for reducing the drive wheel slip by reducing the wheel cylinder hydraulic pressure by the operation of the pressure reducing means during the replacement control due to the generation of the drive wheel slip. Braking control device.