JP2013086626A - Brake control device of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure favorable brake feeling and regenerative energy even if a change occurs in the clearance between a brake pad and a rotor during a cooperative regenerative braking control.SOLUTION: This brake control device of a hybrid vehicle includes a master cylinder, wheel cylinders, a VDC brake fluid pressure unit, a motor controller, and an integrated controller. During brake operation, the integrated controller performs a cooperative regenerative braking control in which a target deceleration is achieved by a basic fluid pressure amount and an additional braking amount (regeneration amount and pressurization amount). When the estimated clearance amount between the brake pad and the rotor changes relative to a design clearance amount, target deceleration characteristics are set according to the amount of change of the clearance from the design value so that the target deceleration at an actual MC pressure generating point is equal to the maximum value of the additional braking amount.

Description

  The present invention is applied to a hybrid vehicle or the like, and brakes for an electric vehicle that performs regenerative cooperative brake control that achieves a braking target value as a sum of a basic hydraulic pressure component and an additional braking component (regeneration component and pressurization component) during braking The present invention relates to a control device.

  As a conventional vehicle brake device, a driver input amount is detected based on a brake pedal stroke, a master cylinder pressure, or the like, and a driver required deceleration is calculated using a driver input amount and a driver required deceleration characteristic map. In order to achieve this driver-requested deceleration, there is known one that generates a braking amount by adding feed-forward control to the negative pressure booster output (basic hydraulic pressure) from the master cylinder (for example, Patent Documents). 1).

  The amount of additional braking in the conventional device refers to the deceleration that adds and shares the shortage of the basic deceleration secured by the basic hydraulic pressure with respect to the driver requested deceleration. It is obtained by at least one of the pump-up pressurization. Then, the additional braking amount is determined by the regenerative gap, the driver requested deceleration is achieved by the sum of the basic hydraulic pressure and the regenerative portion as much as possible, and when the shortage occurs in the total of the basic hydraulic pressure and the regenerative portion, Regenerative cooperative brake control is a control that compensates for the shortage with the pressurization.

JP 2006-96218 A

  However, in the conventional vehicle brake device, a map based on the driver required deceleration characteristic with respect to the driver input amount is set in advance based on the design value of the master cylinder pressure generation stroke, and the driver is used by using this setting map. The requested deceleration is determined. For this reason, when the clearance between the brake pad and the rotor changes in the in-vehicle state, the actual value of the master cylinder pressure generation stroke deviates from the design value of the master cylinder pressure generation stroke. Therefore, when a clearance change occurs, the deceleration does not change smoothly with respect to the brake pedal stroke at the timing immediately before the master cylinder pressure is generated or the master cylinder pressure is generated. There was a problem of lowering the brake feeling.

  The present invention has been made paying attention to the above problems, and achieves good brake feeling and securing of regenerative energy even when a clearance change occurs between the brake pad and the rotor during regenerative cooperative brake control. An object of the present invention is to provide a brake control device for an electric vehicle.

To achieve the above object, a brake control device for an electric vehicle according to the present invention includes a master cylinder, a wheel cylinder, a brake hydraulic pressure actuator, a regenerative braking force control means, a regenerative cooperative brake control means, and a clearance estimation means. The braking target value characteristic setting means and the means provided.
The master cylinder generates a master cylinder pressure corresponding to the brake operation.
The wheel cylinder is provided on each of the front and rear wheels, and applies a hydraulic braking force to each wheel according to the wheel cylinder pressure.
The brake hydraulic pressure actuator is interposed between the master cylinder and the wheel cylinder, and is driven by a pump motor, and the difference between the wheel cylinder pressure and the master cylinder pressure when the pump motor is operated. A differential pressure valve for controlling the pressure.
The regenerative braking force control means is connected to a traveling electric motor coupled to a drive wheel, and controls a regenerative braking force generated by the traveling electric motor.
The regenerative cooperative brake control means uses a brake target value calculated using a brake pedal stroke detection value and a braking target value characteristic map during a brake operation, as a basic hydraulic pressure component based on the master cylinder pressure, and a regeneration target based on the regenerative braking force. And the sum of the additional braking by at least one of the pressure applied by the brake hydraulic pressure actuator and the braking by the brake hydraulic pressure actuator.
The clearance estimating means estimates a clearance amount between a brake pad of the wheel cylinder and a rotor.
The braking target value characteristic setting means is configured to provide a braking target at an actual master cylinder pressure generation stroke that is a brake pedal stroke position at which generation of the master cylinder pressure is started when the estimated clearance amount changes with respect to a design value. The braking target value characteristic is set according to the clearance change amount from the design value so that the value becomes the maximum value for the additional braking or within the allowable range.

Therefore, when setting the braking target value characteristic, if the estimated clearance amount changes with respect to the design value, the braking target value characteristic is set according to the clearance change amount from the design value. This braking target value characteristic is the maximum value range (maximum value and maximum value) for the additional braking that the braking target value in the actual master cylinder pressure generation stroke is added to the basic hydraulic pressure, regardless of the clearance change amount from the design value. (Including values within the allowable range before and after).
That is, in the vehicle-mounted state, the clearance between the brake pad and the rotor changes due to various factors. Due to this clearance change, the actual master cylinder pressure generation stroke may be delayed or too early than the design value. However, regardless of which direction the deviation of the clearance amount from the design value occurs, the characteristic value at the actual master cylinder pressure generation stroke is set to the maximum value range for the additional braking, so that the brake pedal stroke changes smoothly. It is set to the changing braking target value characteristic.
For this reason, when the actual master cylinder pressure generation stroke is delayed from the design value, an increase in the braking target value is not suppressed despite the progress of the brake pedal stroke, and a good brake feeling is achieved.
On the other hand, when the actual master cylinder pressure generation stroke is too early than the design value, the braking target value is not kept low, and the regenerative energy that is effective in improving the fuel efficiency performance and the power consumption performance is achieved.
As a result, it is possible to achieve good brake feeling and securing of regenerative energy even when a clearance change occurs between the brake pad and the rotor during regenerative cooperative brake control.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a brake system diagram illustrating a configuration of a hybrid vehicle by front wheel drive to which a brake control device according to a first embodiment is applied. It is a brake fluid pressure circuit diagram showing the VDC brake fluid pressure unit in the brake control device of Example 1. It is a control block diagram which shows the regeneration cooperation brake control system in the brake control apparatus of Example 1. It is a flowchart which shows the flow of the target deceleration characteristic map setting process performed in the target deceleration characteristic map setting part of the integrated controller in the brake control apparatus of Example 1. It is a figure which shows the lateral G sensitive clearance map used for estimation of the lateral G sensitive clearance in the target deceleration characteristic map setting process of Example 1. FIG. It is a figure which shows the magnitude relationship with the design value of the estimation of an actual MC pressure generation point, and an actual MC pressure generation point in the target deceleration characteristic map setting process of Example 1. It is a flowchart which shows the flow of the regenerative cooperative brake control process performed in the target deceleration calculation part and regenerative cooperative brake control part of the integrated controller in the brake control apparatus of Example 1. It is a figure which shows an example of the relationship characteristic of the operating current value to the differential pressure | voltage valve with respect to the target differential pressure used when determining a pressurization part command value by the regeneration cooperation brake control process of Example 1. FIG. The target deceleration (= driver required deceleration) is achieved by the sum of the basic hydraulic pressure component, the regenerative component, and the pressurized component by the regenerative coordinated braking system using VDC. It is control conceptual explanatory drawing which shows an example. It is a subject explanatory drawing which shows regenerative cooperation brake control action using a standard target deceleration characteristic map in case a real loss stroke is larger than a design value loss stroke in a hybrid car carrying a brake control device of a comparative example. It is a subject explanatory drawing which shows regenerative cooperation brake control action using a standard target deceleration characteristic map in case a real loss stroke is smaller than a design value loss stroke in a hybrid vehicle carrying a brake control device of a comparative example. It is a time chart which shows an example of a regeneration cooperation brake control effect | action when the hybrid vehicle carrying the brake control apparatus of Example 1 stops by maintaining a fixed deceleration by brake operation. FIG. 6 is a comparative effect explanatory diagram showing a comparative effect by target deceleration characteristics by offset correction when actual loss stroke (small clearance) <design value loss stroke in the brake control device of Example 1; FIG. 6 is a comparative effect explanatory diagram showing a comparative effect by a target deceleration characteristic by offset correction when actual loss stroke (large clearance)> design value loss stroke in the brake control device of Example 1; In the brake control apparatus of Example 2, it is comparative effect explanatory drawing which shows the comparative effect by the target deceleration characteristic by offset correction | amendment & gradient correction | amendment when an actual loss stroke (clearance small) <design value loss stroke. In the brake control apparatus of Example 2, it is a comparative effect explanatory drawing which shows the comparative effect by the target deceleration characteristic by offset correction | amendment & gradient correction | amendment at the time of real loss stroke (clearance large)> design value loss stroke.

  Hereinafter, the best mode for realizing a brake control device for an electric vehicle according to the present invention will be described based on Example 1 and Example 2 shown in the drawings.

First, the configuration will be described.
The configuration of the brake control device of the hybrid vehicle (an example of an electric vehicle) in the first embodiment is “overall configuration”, “block configuration of regenerative cooperative brake control system”, “target deceleration characteristic map setting processing configuration”, “regeneration” The description will be divided into “cooperative brake control processing configuration”.

[overall structure]
FIG. 1 shows a configuration of a hybrid vehicle which is an example of an electric vehicle driven by front wheels to which the brake control device of the first embodiment is applied. FIG. 2 shows a VDC brake hydraulic unit that is an example of a brake hydraulic actuator. Hereinafter, based on FIG.1 and FIG.2, the structure of the regeneration cooperation brake system using VDC is demonstrated.

  As shown in FIG. 1, the brake deceleration generation system of the brake control device of the first embodiment includes a brake fluid pressure generating device 1, a VDC brake fluid pressure unit 2 (brake fluid pressure actuator), a stroke sensor 3, and a left sensor. A front wheel wheel cylinder 4FL, a right front wheel wheel cylinder 4FR, a left rear wheel wheel cylinder 4RL, a right rear wheel wheel cylinder 4RR, and an electric motor 5 for traveling are provided.

  In other words, a regenerative cooperative brake system using an existing VDC system (VDC stands for “Vehicle Dynamics Control”) is used. The VDC system is a system that performs vehicle behavior control (= VDC control) that prevents skidding and exhibits excellent running stability when the vehicle posture is disturbed due to corner entry at high speed or sudden steering operation. In VDC control, for example, if the turning behavior is sensed as being oversteered, the front wheel outside the corner is braked, and conversely if the turning behavior is sensed as being understeered, the driving power is reduced and the corners of the rear wheels are reduced. Brake the inner tire.

  The brake fluid pressure generating device 1 is basic fluid pressure generating means for generating a basic fluid pressure corresponding to a brake operation by a driver. As shown in FIGS. 1 and 2, the brake fluid pressure generator 1 includes a brake pedal 11, a negative pressure booster 12, a master cylinder 13, and a reserve tank 14. That is, the driver's brake pedal force applied to the brake pedal 11 is boosted by the negative pressure booster 12, and the primary hydraulic pressure and the secondary hydraulic pressure by the master cylinder pressure are generated by the master cylinder 13. At this time, it is designed in advance that the deceleration generated by the master cylinder pressure is smaller than the target deceleration (= driver required deceleration).

  The VDC brake fluid pressure unit 2 is interposed between the brake fluid pressure generator 1 and the wheel cylinders 4FL, 4FR, 4RL, 4RR of each wheel. The VDC brake hydraulic pressure unit 2 includes hydraulic pumps 22 and 22 driven by a VDC motor 21 (pump motor), and is a brake hydraulic pressure actuator that controls increase / hold / depressurization of the master cylinder pressure. The VDC brake fluid pressure unit 2 and the brake fluid pressure generator 1 are connected by a primary fluid pressure pipe 61 and a secondary fluid pressure pipe 62. The VDC brake hydraulic unit 2 and the wheel cylinders 4FL, 4FR, 4RL, 4RR of each wheel 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. ing. In other words, at the time of brake operation, the master cylinder pressure generated by the brake fluid pressure generator 1 is pressurized by the VDC brake fluid pressure unit 2 and applied to the wheel cylinders 4FL, 4FR, 4RL, 4RR of each wheel to provide the hydraulic braking force. Trying to get.

  As shown in FIG. 2, the specific configuration of the VDC brake hydraulic unit 2 includes a VDC motor 21, hydraulic pumps 22 and 22 driven by the VDC motor 21, reservoirs 23 and 23, and a master cylinder pressure sensor 24. And having. As solenoid valves, a first M / C cut solenoid valve 25 (differential pressure valve), a second M / C cut solenoid valve 26 (differential pressure valve), holding solenoid valves 27, 27, 27, 27, a pressure reducing solenoid valve 28, 28, 28, 28. The first M / C cut solenoid valve 25 and the second M / C cut solenoid valve 26 control the differential pressure between the wheel cylinder pressure (downstream pressure) and the master cylinder pressure (upstream pressure) when the VDC motor 21 is operated.

  The stroke sensor 3 is means for detecting a brake pedal operation amount by a driver with a potentiometer or the like. This stroke sensor 3 is a component added to an existing VDC system as a configuration for detecting a target deceleration (= driver-requested deceleration) that is necessary information in regenerative cooperative brake control.

  Each of the wheel cylinders 4FL, 4FR, 4RL, 4RR is set as a disc brake mechanism for each of the front and rear wheels, and the hydraulic pressure from the VDC brake hydraulic pressure unit 2 is applied. When a brake fluid pressure is applied to each wheel cylinder 4FL, 4FR, 4RL, 4RR, a hydraulic braking force is applied to the front and rear wheels by sandwiching the rotor 42 (= disc rotor) by the pair of brake pads 41, 41. To do.

  The travel electric motor 5 is provided as a travel drive source for the left and right front wheels (drive wheels) 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 by driving the motor while 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 generated power is charged to the battery. That is, the load applied to the rotational drive of the left and right front wheels is the regenerative braking force. The driving system for the left and right front wheels (drive wheels) provided with the traveling electric motor 5 is provided with an engine 10 as a traveling drive source in addition to the traveling electric motor 5, and is driven to the left and right front wheels via the transmission 11. Transmit power.

  As shown in FIG. 1, the brake deceleration control system of the brake control device according to the first embodiment includes a brake controller 7, a motor controller 8 (regenerative braking force control means), an integrated controller 9, and an engine controller 12. I have.

  The brake controller 7 inputs a command from the integrated controller 9 and pressure information from the master cylinder pressure sensor 24 of the VDC brake hydraulic pressure unit 2. Then, a drive command is output to the VDC motor 21 and solenoid valves 25, 26, 27, 28 of the VDC brake hydraulic unit 2 according to a predetermined control law. The brake controller 7 controls the differential pressure between the wheel cylinder pressure (downstream pressure) and the master cylinder pressure (upstream pressure) when a pressure increase command is input from the integrated controller 9 during regenerative cooperative brake control. The differential pressure control is performed by differential pressure control based on operating current values to the first M / C cut solenoid valve 25 and the second M / C cut solenoid valve 26 and pump-up pressure increase by the VDC motor 21. The brake controller 7 performs the VDC control, TCS control, ABS control, and the like in addition to the regenerative cooperative brake control.

  The motor controller 8 is connected to a traveling electric motor 5 connected to left and right front wheels, which are drive wheels, via an inverter 13. When the regenerative braking command is input from the integrated controller 9 during the regenerative cooperative brake control, the regenerative braking force control means controls the regenerative braking force generated by the traveling electric motor 5 according to the input regenerative braking command. The motor controller 8 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.

  When the brake is operated, the integrated controller 9 sets the target deceleration to at least one of the basic hydraulic pressure by the master cylinder pressure and the additional braking (regeneration by the regenerative braking force and the pressurization by the VDC brake hydraulic pressure unit 2). On the other hand, regenerative cooperative brake control is achieved as a sum of At this time, the target deceleration is determined based on the pedal stroke sensor value from the stroke sensor 3 and the set target deceleration characteristic map. The integrated controller 9 includes battery charge capacity information from the battery controller 91, vehicle speed information from the vehicle speed sensor 92, brake operation information from the brake switch 93, brake pedal stroke information from the stroke sensor 3, and master cylinder pressure sensor 24. Master cylinder pressure information, etc. are input. As the vehicle speed sensor 92, wheel speed rotation number detecting means capable of detecting a vehicle speed up to an extremely low vehicle speed range is used.

[Block configuration of regenerative cooperative brake control system]
FIG. 3 is a block diagram of a regenerative cooperative brake control system in the brake control device according to the first embodiment. Hereinafter, the block configuration of the regenerative cooperative brake control system will be described with reference to FIG.

  As shown in FIG. 3, the regenerative cooperative brake control system according to the first embodiment includes a brake controller 7, a motor controller 8, and an integrated controller 9. The integrated controller 9 includes a reference map setting unit 9a (reference braking target value characteristic setting unit), a target deceleration characteristic map setting unit 9b (braking target value characteristic setting unit), and a target deceleration calculation unit 9c (regenerative cooperative braking). Control means), regenerative cooperative brake control section 9d (regenerative cooperative brake control means), and clearance estimation section 9e (clearance estimation means).

  The reference map setting unit 9a sets the stroke position at which the brake pedal stroke amount reaches the design value loss stroke as the design value MC pressure generation point. Then, the target deceleration (braking target value) at the design value MC pressure generation point is added as the maximum value for braking, and the map is based on the reference target deceleration characteristic (reference braking target value characteristic) that changes smoothly with stroke change. Is a map storage setting unit for setting in advance.

The target deceleration characteristic map setting unit 9b is configured to change the target deceleration characteristic map when the estimated clearance value estimated by the clearance estimation unit 9e changes with respect to a predetermined clearance design value (design value loss stroke). Is set by correction.
The target deceleration characteristics map is based on the reference so that the target deceleration (braking target value) at the actual MC pressure generation point (= position where the actual loss stroke is reached) will be the maximum value for additional braking during braking. The reference target deceleration characteristic read from the map setting unit 9a is set by offset correction for shifting in the stroke direction. The actual MC pressure generation point corresponds to an actual master cylinder pressure generation stroke that is a brake pedal stroke position where generation of the master cylinder pressure is started.

  The target deceleration calculation unit 9c is based on the target deceleration characteristic based on the target deceleration characteristic map set by the target deceleration characteristic map setting unit 9b and the pedal stroke sensor value from the stroke sensor 3. Calculate the speed (= driver requested deceleration).

  The regenerative cooperative brake control unit 9d inputs the target deceleration calculated by the target deceleration calculation unit 9a, the MC pressure sensor value from the master cylinder pressure sensor 24, and the vehicle speed sensor value from the vehicle speed sensor 92. Then, the basic hydraulic pressure is determined based on the MC pressure sensor value, the regeneration is determined based on the vehicle speed sensor value, and the target deceleration is achieved as much as possible with the basic hydraulic pressure plus the sum of the regeneration. When this occurs, regenerative cooperative brake control calculation is performed to compensate for the shortage by the pressurization. According to this calculation result, a regeneration component command corresponding to the regeneration component is output to the motor controller 8, and a pressurization component command corresponding to the pressurization component is output to the brake controller 7.

  The clearance estimation unit 9e inputs information from the lateral acceleration sensor 94, the prefill controller 95, and the raindrop sensor 96, and determines the clearance amount between the brake pads 41 of the wheel cylinders 4FL, 4FR, 4RL, 4RR and the rotor 42. Of these, the increase or decrease from the steady clearance is estimated.

[Target deceleration characteristics map setting processing configuration]
FIG. 4 shows a flow of a target deceleration characteristic map setting process executed by the target deceleration characteristic map setting unit 9b of the integrated controller 8 in the brake control device of the first embodiment (target braking target value characteristic setting means). Hereinafter, each step of FIG. 4 showing the setting processing configuration of the target deceleration characteristic map will be described.

In Step S1, the lateral acceleration (= lateral G) detected by the lateral acceleration sensor 94 and the clearance amount map shown in FIG. The sensitive clearance is estimated and the process proceeds to step S2.
Here, the “clearance amount map” is determined by having a characteristic (for example, a quadratic curve characteristic) in which the clearance amount is zero when the lateral G is zero and the clearance amount increases as the lateral G increases. . Then, the clearance amount map shown in FIG. 5 is corrected as needed by learning control in which the maximum value of the lateral G is stored and updated from a large number of braking experiences and the estimated clearance amount at the maximum lateral G stored value is obtained.

In step S2, following the estimation of the lateral G-sensitive clearance in step S1, the prefill clearance that is a change amount (decrease amount) of the clearance amount according to the approach state of the brake pad 41 and the rotor 42 is learned during the prefill control intervention. Estimate and proceed to step S3.
Here, “pre-fill control” uses a VDC system, and when the driver depresses the brake pedal, the predetermined hydraulic pressure is supplied to the wheel cylinder in advance, and the brake pad is brought closer to the rotor, thereby reducing the idle stroke. Refers to the technology to be
This pre-fill control is also called fill-up control, and for more detailed contents, refer to, for example, Japanese Patent Application Laid-Open No. 2010-247793. The prefill clearance is zero when no prefill control is performed.

In step S3, following the estimation of the prefill clearance in step S2, when it is determined that it is rainy from the signal from the raindrop sensor 96, the rainy weather is a change (decrease) in the amount of clearance according to the formation of the water film. The detected clearance is learned and estimated, and the process proceeds to step S4.
Here, “water film” refers to a phenomenon in which water adheres to the surfaces of the brake pad 41 and the rotor 42 on a rainy day, and this forms a water film as the rotor rotates. If it is not determined that it is raining, the rain detection clearance is zero.

In step S4, following the estimation of the rain detection clearance in step S3, the actual MC pressure generation point is determined based on the steady clearance between the brake pad 41 and the rotor 42 and the clearance estimated in steps S1 to S3. Estimate and go to step S5.
Here, the “steady clearance” refers to a clearance amount between the brake pad 41 and the rotor 42 under a condition where there is no factor for changing the clearance. For example, it is obtained by detecting the brake pedal stroke position (actual MC pressure generation point) at which the master cylinder pressure is actually generated at the time of the brake operation in which the clearance estimated in Steps S1 to S3 becomes zero. Further, the steady clearance is renewed every time a brake operation is experienced in which the clearance estimated in Steps S1 to S3 becomes zero in order to cope with secular changes such as wear of the brake pads 41.
The actual MC pressure generation point (= estimated clearance amount) is
Actual MC pressure generation point = (steady clearance) + (lateral G sensitive clearance)-(prefill clearance)-(rainy weather detection clearance)
It is estimated by the following formula.

In step S5, following the estimation of the actual MC pressure generation point in step S4, it is determined whether or not the estimated actual MC pressure generation point is smaller than (design value−α). If YES (actual MC pressure generation point <design value−α), the process proceeds to step S6. If NO (actual MC pressure generation point ≧ design value−α), the process proceeds to step S7. That is, as shown in FIG. 6, when the estimated clearance amount is smaller than (design value−α), the target deceleration characteristic map is corrected.
Here, α is a value that defines an upper limit value and a lower limit value that determine an allowable range in which a target required characteristic can be achieved with respect to a design value for obtaining an ideal required characteristic.

  In step S6, following the determination that the actual MC pressure generation point <design value−α in step S5, the regenerative braking force generation start point of the reference target deceleration characteristic is offset-corrected in a direction that shortens the pedal stroke. A target deceleration characteristic map is set (FIG. 13). From step S6, the process proceeds to return.

  In step S7, following the determination that the actual MC pressure generation point ≧ design value−α in step S5, it is determined whether or not the estimated actual MC pressure generation point is greater than (design value + α). If YES (actual MC pressure generation point> design value + α), the process proceeds to step S8, and if NO (actual MC pressure generation point ≦ design value + α), the process proceeds to return. That is, as shown in FIG. 6, when the estimated clearance amount is larger than (design value + α), the target deceleration characteristic map is corrected.

  In step S8, following the determination that the actual MC pressure generation point> design value + α in step S7, the target point is obtained by offset-correcting the regenerative braking force generation start point of the reference target deceleration characteristic in the direction of increasing the pedal stroke. A deceleration characteristic map is set (FIG. 14). From step S8, the process proceeds to return.

[Regenerative cooperative brake control processing configuration]
FIG. 7 shows a flow of regenerative cooperative brake control processing executed by the target deceleration calculating unit 9c and the regenerative cooperative brake control unit 9d of the integrated controller 8 in the brake control device of the first embodiment (regenerative cooperative brake control means). Hereinafter, each step of FIG. 7 showing the regenerative cooperative brake control processing configuration will be described. Note that the regenerative cooperative brake control process in FIG. 7 starts from the point in time when the start of the brake operation is determined.

  In step S21, the VDC motor 21 in a stopped state is set in a motor driving state before starting the brake operation, and the process proceeds to step S22.

  In step S22, following the determination that the motor is driven in step S21 or the vehicle is not stopped in step S27, the master cylinder pressure information from the master cylinder pressure sensor 24 and the pedal stroke amount from the stroke sensor 3 are determined. The information, the vehicle speed information from the vehicle speed sensor 92, and the target deceleration characteristic map set in the flowchart of FIG. 4 are read, and the process proceeds to step S23.

In step S23, following the reading of the necessary information and the target deceleration characteristic map in step S22, the brake pedal depression speed is calculated, the target deceleration characteristic map is corrected based on the pedal depression speed, and the process proceeds to step S24.
Here, the correction of the target deceleration characteristic map is performed when the pedal depression speed information included in the set target deceleration characteristic map is different from the pedal depression speed calculated in step S23. That is, as the calculated brake pedal depression speed becomes faster than the pedal depression speed information, offset correction is performed so as to shift in the stroke direction so as to shorten the loss stroke to the actual MC pressure generation point. If the pedal depression speed information in the target deceleration characteristics map matches the calculated pedal depression speed, or if both speed differences are within the allowable range, the target deceleration characteristics map that has been set is corrected. Is not required.

  In step S24, following the correction of the target deceleration characteristic map based on the pedal depression speed in step S23, the brake pedal stroke position corresponding to the driver input is determined based on the brake pedal stroke sensor value and the corrected target deceleration characteristic map. The target deceleration is calculated and the process proceeds to step S25.

  In step S25, following calculation of the target deceleration in step S24, the basic hydraulic pressure is determined based on the MC pressure sensor value at that time, and the maximum possible pressure is determined based on the vehicle speed sensor value and battery SOC at that time. Decide which part will be regenerated. Then, the remaining deceleration amount obtained by subtracting the basic hydraulic pressure component and the regenerative component from the target deceleration is determined to be shared by the pressurized component. That is, regenerative cooperative brake control calculation is performed to achieve the target deceleration by the sum of basic hydraulic pressure + regeneration + pressurization, and the process proceeds to step S26.

In step S26, following the regeneration cooperative brake control calculation in step S25, the regeneration command value corresponding to the regeneration component is determined from the additional target braking force with respect to the basic hydraulic pressure component, and the regeneration component command (including the zero command) is determined. Is output to the motor controller 8. At the same time, among the additional target braking force with respect to the basic hydraulic pressure component, a pressurization component command value corresponding to the pressurization component is determined, and the pressurization component command (including zero command) is output to the brake controller 7, and the process proceeds to step S27. move on.
Here, when the regenerative command is input, the motor controller 8 uses the regenerative component as a target regenerative braking force, and performs regenerative torque control by feedforward control that determines a regenerative current value to the traveling electric motor 5. When the pressurization component command is input, the brake controller 7 sets the pressurization component as the target differential pressure, and determines the operating current value to both the M / C cut solenoid valves 25 and 26 based on the relational characteristics as shown in FIG. Differential pressure control is performed by feedforward control.

  In step S27, following the output of the regeneration command and the pressurization command in step S26, it is determined whether the vehicle has stopped based on the vehicle speed sensor value from the vehicle speed sensor 92. If YES (vehicle stop state), the process proceeds to step S28, and if NO (vehicle non-stop state), the process returns to step S22.

  In step S28, following the determination that the vehicle is in a stopped state in step S27, the motor drive of the VDC motor 21 is stopped and the process proceeds to the end.

Next, the operation will be described.
First, “the problem in the regenerative cooperative brake control of the comparative example” will be described. Next, the operation of the hybrid vehicle brake control apparatus according to the first embodiment will be described separately for “regenerative cooperative brake control operation”, “target deceleration characteristic map setting operation”, and “clearance estimation operation”.

[Problems in regenerative cooperative brake control of comparative example]
Regenerative coordinated brake control using VDC adds a hydraulic pressure that cannot be compensated for by the VDC brake hydraulic pressure unit when a scene that cannot be compensated for by the basic hydraulic pressure and the regenerative component occurs with respect to the target deceleration. This is the control to achieve the required deceleration of the driver. A regenerative cooperative brake system using VDC for performing this regenerative cooperative brake control will be described with reference to FIG.

  In the case of an existing conventional VDC, a target deceleration requested by the driver is obtained by a basic hydraulic pressure component by a negative pressure booster during brake operation. On the other hand, the basic hydraulic pressure component by the negative pressure booster during braking operation is offset from the target deceleration requested by the driver so as not to reach the target deceleration, and the regeneration gap for the target deceleration is set. Thus, by setting the regenerative gap by the maximum regenerative torque, the regenerative gap of the target deceleration becomes insufficient with respect to the target deceleration requested by the driver. Therefore, when the maximum regenerative torque is generated, the target deceleration requested by the driver is achieved by the negative pressure booster (basic hydraulic pressure) and the regenerative brake (regenerative component) to maximize the regenerative function.

  However, for example, due to vehicle speed conditions, battery charge capacity conditions, etc., it may not be possible to compensate for the target deceleration that is required by the driver for the target deceleration that is insufficient for the basic hydraulic pressure, but only for the regeneration. is there. Therefore, as shown in FIG. 9, the target deceleration requested by the driver is achieved by the sum of the negative pressure booster (basic fluid pressure) and the regenerative brake (regeneration), and the shortage is achieved by the VDC brake hydraulic unit ( It is a regenerative cooperative brake system using VDC that compensates for the increase in pressure).

  Therefore, an inexpensive regenerative cooperative brake system using VDC can be configured by simply changing the characteristics of the negative pressure booster, the characteristics of the VDC brake hydraulic unit, and adding a stroke sensor to the existing conventional VDC. Can do. That is, the safety function of the conventional VDC is expanded (safety function + regenerative cooperation function).

  In the regenerative cooperative brake system, as shown by the solid line characteristics (target G characteristics) in FIGS. 10 and 11, the stroke change is performed so that the target deceleration matches the value of the regeneration gap at the stroke position where the design value loss stroke is reached. As a comparative example, a target deceleration characteristic that smoothly changes with respect to the above is set.

Here, “the stroke position at which the design value loss stroke is reached” means that the master cylinder pressure starts to be generated in the nominal design model as shown in the deceleration characteristics due to the MC pressure indicated by the dotted lines in FIGS. 10 and 11. This is the meaning of the design value MC pressure generation point.
The “regenerative gap” is the amount of deviation of the additional braking that is added to the basic hydraulic pressure indicated by the deceleration characteristics due to MC pressure when the target deceleration is achieved. Since the amount is given by the maximum value of the regenerative torque, it is called a regenerative gap.

  In the case of this comparative example, it is assumed that the actual MC pressure generation point that reaches the actual loss stroke due to the change in the clearance between the brake pad and the rotor has shifted from the design value MC pressure generation point. At this time, as described below, the target deceleration characteristic is uncomfortable.

(a) When the master cylinder pressure generation start point is delayed (Fig. 10)
A case where the actual MC pressure generation point B (hereinafter, “point B”) is delayed from the design value MC pressure generation point A (hereinafter, “point A”) as shown in FIG. 10 will be described.
The characteristic value at the point A preceding the point B is a value obtained by adding the regeneration gap to the basic hydraulic pressure component (zero), and a target deceleration corresponding to the regeneration gap is obtained. On the other hand, the characteristic value at the point B that arrives later than the point A is a value obtained by adding the expected increase in the basic hydraulic pressure to the value at the point A. However, at point A, the basic hydraulic pressure component is zero as in point A due to the delay in starting the generation of the master cylinder pressure, so that, as with point A, the target deceleration corresponding to the regeneration gap is obtained. That is, the target deceleration characteristic when the brake pedal stroke advances from point A to point B is a characteristic that maintains the target deceleration according to the regeneration gap, as shown in the frame region of the arrow D in FIG. In other words, there occurs a scene where the target deceleration does not increase even though the target deceleration must increase as the brake pedal stroke progresses.

  Therefore, when the point B is later than the point A, the target deceleration cannot be achieved in the brake pedal stroke area after the point A because the generation of the basic hydraulic pressure is delayed. In addition, when the brake pedal stroke advances or returns including the region between the points A and B, a stepped feeling that makes the vehicle deceleration constant with respect to the brake operation occurs, and the pedal feeling is impaired.

(b) Master cylinder pressure generation start point is too early (Fig. 11)
A case where the actual MC pressure generation point C (hereinafter, “point C”) is earlier than the point A, which is the design value MC pressure generation point, will be described as shown in FIG.
The characteristic value at the point C preceding the point A is a value obtained by adding a value smaller than the regeneration gap to the basic hydraulic pressure component (zero), and a target deceleration corresponding to a value smaller than the regeneration gap is obtained. On the other hand, the characteristic value at the point A that arrives after the point C is gradually increased from the value at the point C, and is a value obtained by adding the regeneration gap to the basic hydraulic pressure, and the target value corresponding to the regeneration gap. Deceleration is obtained. However, since the generation of the master cylinder pressure is too early, the additional braking amount is smaller than the regenerative gap at point C, and the deceleration of the basic hydraulic pressure has already occurred at point A, so the additional braking amount is the regenerative gap. Smaller value. In other words, the target deceleration characteristic is a characteristic in which the additional braking amount remains smaller than the regenerative gap according to the early generation of the basic hydraulic pressure. In other words, the hatching region indicated by the arrow E in FIG. 11 becomes the regenerative torque limiting region because the additional braking is suppressed by the early generation of the basic hydraulic pressure.

  Therefore, when the point C is too early than the point A, the control is achieved to achieve the target deceleration due to a smooth change, but the regenerative torque is limited in the region up to the design value loss stroke. The fuel consumption gets worse. In the case of an electric vehicle, the electricity cost is worsened.

[Regenerative cooperative brake control action]
In the case of a hybrid vehicle, at the time of braking, not all braking energy is consumed as thermal energy as in an engine vehicle, but as much energy as possible among the braking energy is recovered as regenerative energy in the battery to improve fuel efficiency. Is important above. Hereinafter, the regenerative cooperative brake control action reflecting this will be described.

  When the brake operation is performed, in the flowchart of FIG. 7, the process proceeds from step S21 → step S22 → step S23 → step S24 → step S25 → step S26 → step S27. While it is determined in step S27 that the vehicle is not stopped, the flow of steps S22 → step S23 → step S24 → step S25 → step S26 → step S27 is repeated to perform the regenerative cooperative brake control. Run. If it is determined in step S27 that the vehicle is in a stopped state, the process proceeds from step S27 to step S28 → end, and the regenerative cooperative brake control is terminated.

  That is, in step S24, the target deceleration corresponding to the brake pedal stroke position by the driver input is calculated based on the brake pedal stroke sensor value and the set or corrected target deceleration characteristic map. In step S25, the basic hydraulic pressure is determined based on the MC pressure sensor value at that time, and the maximum possible regeneration is determined based on the vehicle speed sensor value and the battery SOC at that time. The remaining deceleration amount obtained by subtracting the basic hydraulic pressure component and the regenerative component from the target deceleration is determined to be shared by the pressurized component. In step S <b> 26, the regeneration command value corresponding to the regeneration component is determined from the additional target braking force with respect to the basic hydraulic pressure component, and the regeneration command (including the zero command) is output to the motor controller 8. At the same time, of the additional target braking force with respect to the basic hydraulic pressure, a pressurization command value corresponding to the pressurization is determined, and the pressurization command (including the zero command) is output to the brake controller 7.

  Therefore, at the time of regenerative cooperative brake control, the regenerative torque control is performed by feedforward control in which the regenerative component is set as the target regenerative braking force and the regenerative current value to the traveling electric motor 5 is determined in the motor controller 8 that inputs the regenerative command. Is called. Then, in the brake controller 7 to which the pressurization component command is input, the pressurization component is set as the target differential pressure, and the rotation increase command to the VDC motor 21 and the operating current value to both the M / C cut solenoid valves 25 and 26 are determined. Differential pressure control is performed by feedforward control (FIG. 8).

  An example of the regenerative cooperative brake control operation when the hybrid vehicle equipped with the brake control device of the first embodiment stops with a constant deceleration by a brake operation will be described based on the time chart of FIG.

  A constant vehicle speed is maintained from time t0 to time t1, and the target deceleration increases from 0G to aG from time t1 when the brake operation is started to time t2 when the generation of the master cylinder pressure is started. On the other hand, the target deceleration is achieved by the regenerative component that increases and the pressurization component (VDC_P / U) due to the increasing characteristic of the wheel cylinder pressure. Since there is a loss stroke (rod stroke 0mm to bmm) where no master cylinder pressure is generated, there is no basic hydraulic pressure.

  When the loss stroke ends at time t2 and generation of the master cylinder pressure begins, the target deceleration increases from aG to cG from time t2 until time t3 when the target deceleration reaches a constant value cG. To do. On the other hand, the target deceleration is achieved by the basic hydraulic pressure component due to the increase characteristic of the master cylinder pressure, the regenerative component that increases, and the pressurization component (VDC_P / U) due to the decrease characteristic of the wheel cylinder pressure.

  When the rod stroke is fixed at dmm at time t3, the target deceleration is maintained at cG from time t3 until time t4 when the vehicle speed at which the regenerative restriction is started is reached. On the other hand, the target deceleration is determined based on the basic hydraulic pressure due to the constant characteristic of the master cylinder pressure, the maximum regenerative amount allowed under the conditions at that time, and the pressurized amount due to the constant characteristic of the wheel cylinder pressure (VDC_P / U ) And achieved.

  Then, when the restriction on regeneration is started at time t4, the target deceleration is maintained as cG from time t4 until time t5 when the vehicle speed becomes zero with the regeneration being zero. On the other hand, the target deceleration is achieved by the basic hydraulic pressure component due to the constant characteristic of the master cylinder pressure, the regenerative component due to the decrease property, and the pressurization component (VDC_P / U) due to the rising property of the wheel cylinder pressure.

  When the regeneration becomes zero at time t5, the target deceleration is maintained as cG from time t5 to time t6 when the vehicle stops. On the other hand, the target deceleration is achieved by the basic hydraulic pressure due to the constant characteristic of the master cylinder pressure and the pressurization amount (VDC_P / U) due to the constant characteristic of the wheel cylinder pressure. In the region from time t5 to time t6, since the regenerative component is zero, the deceleration dependency due to the pressurized component (VDC_P / U) increases.

  Therefore, in the regenerative cooperative brake control executed at the time of the brake operation, as shown in the target deceleration characteristic at the top of FIG. 12, the occupied area as the regenerative portion of the braking energy expressed in the entire region is set as the regenerative energy portion. It can be collected in the on-board battery.

[Target deceleration characteristics map setting action]
As described in the problem of the comparative example, the actual value of the master cylinder pressure generation start point inevitably deviates from the design value due to a change in the clearance amount between the brake pad 41 and the rotor 42. . For this reason, it is necessary to estimate the amount of deviation of the master cylinder pressure generation start point due to the change in the clearance amount and to set the target deceleration characteristic appropriately. The target deceleration characteristic map setting operation that reflects this will be described below.

When the actual MC pressure generation point is (design value−α) ≦ actual MC pressure generation point ≦ (design value + α), in the flowchart of FIG. 4, step S1, step S2, step S3, step S4, step S5, step The process proceeds from S7 to return.
That is, the reference target deceleration characteristic Ga is set as the target deceleration characteristic as it is without correcting the reference target deceleration characteristic based on the design value.

Then, when the actual MC pressure generation point <(design value−α), in the flowchart of FIG. 4, the process proceeds from step S 1 → step S 2 → step S 3 → step S 4 → step S 5 → step S 6 → return.
That is, in step S6, as shown in FIG. 13, the target deceleration characteristic map Gc is set by offset-correcting the regenerative braking force generation start point (design value) of the reference target deceleration characteristic Ga in the direction in which the pedal stroke becomes shorter. Is done.

On the other hand, when the actual MC pressure generation point> (design value + α), in the flowchart of FIG. 4, the process proceeds from step S1, step S2, step S3, step S4, step S5, step S7, step S8, and return.
That is, in step S8, as shown in FIG. 14, the target deceleration characteristic map Gb is set by offset-correcting the regenerative braking force generation start point (design value) of the reference target deceleration characteristic Ga in the direction in which the pedal stroke becomes longer. Is done.

  Therefore, when the actual MC pressure generation point (= actual loss stroke) estimated in step S4 changes with respect to the clearance design value, the target deceleration characteristic map corresponding to the clearance change amount is set. As shown in FIGS. 13 and 14, the target deceleration characteristics maps Gb and Gc are the maximum of the additional braking amount that the braking target value in the actual loss stroke is added to the basic hydraulic pressure regardless of the clearance change amount. The value is an appropriate value.

  That is, as described in the problem of the comparative example, the clearance between the brake pad 41 and the rotor 42 in the vehicle-mounted state varies depending on various factors (lateral acceleration generation, prefill control intervention, water film formation, etc.). Due to this clearance change, the actual MC pressure generation points B and C (= actual loss stroke) may be delayed or too early than the design value loss stroke A. However, regardless of which direction the deviation from the clearance design value occurs, the value that is offset by the regenerative gap, which is the maximum value for braking, is added on the actual MC pressure generation points B and C (= actual loss stroke) on the characteristic line. The value is set in the target deceleration characteristic maps Gb and Gc that change smoothly with respect to the brake pedal stroke change.

  For example, when the actual MC pressure generation point B is delayed from the design value loss stroke A, as shown in the target deceleration characteristic Gb after the countermeasure in FIG. 14, the characteristic changes smoothly with respect to the entire change in the brake pedal stroke. Will be set to. In other words, from zero stroke to point B, the curve gradually rises up to the regenerative gap. The stroke area after point B follows the deceleration characteristic due to MC pressure while maintaining the regenerative gap interval. It is considered as a drawing characteristic.

  Therefore, as shown in the target deceleration characteristic Gb ′ before the countermeasure in FIG. 14, the increase in the target deceleration can be suppressed even though the brake pedal stroke advances in the stroke region from the point A to the point B. Absent. That is, as shown in the target deceleration characteristic Gb after countermeasures in FIG. 14, the target deceleration smoothly increases with the progress of the brake pedal stroke in the stroke region from point A to point B, and the brake feeling is good. Is achieved.

  On the other hand, when the actual MC pressure generation point C is too early than the design value loss stroke A, as shown in the target deceleration characteristic Gc after the countermeasure in FIG. It will be set to the value characteristic. In other words, from zero stroke to point C, it is a characteristic that draws a curve that gradually rises up to the regenerative gap, and the stroke area after point C follows the deceleration characteristic by MC pressure while maintaining the interval for the regenerative gap. It is considered as a drawing characteristic.

  Therefore, as shown in the target deceleration characteristic Gc ′ before the countermeasure in FIG. 13, the target deceleration is not suppressed low in the region up to the design value loss stroke. That is, as shown in the target deceleration characteristic Gc after countermeasures in FIG. 13, the additional braking force is expanded in the stroke region before the point C, and the braking force component due to the regenerative gap is added as the additional braking force in the stroke region after the point C. The remaining high target deceleration is assumed. Thereby, securing of regenerative energy that is effective in improving fuel efficiency is achieved.

Next, a method for setting a target deceleration characteristic by offset correction in the first embodiment will be described.
First, the reference map setting unit 9a determines the design value MC pressure generation point A at the brake pedal stroke position based on the design value loss stroke. Then, a reference map based on the reference target deceleration characteristic Ga set so as to become the maximum value of the target braking force added (= regenerative gap) at the design value MC pressure generation point A is set in advance. Then, in the target deceleration characteristic map setting unit 9b, based on the estimation of the clearance between the brake pad 41 and the rotor 42 in the clearance estimation unit 9e, the brake pedal stroke position where the master cylinder pressure is actually generated during the brake operation. The actual MC pressure generation points B and C are estimated.

  When the estimated actual MC pressure generation point B is later than the design value MC pressure generation point A, as shown in FIG. 14, the additional braking amount at the actual MC pressure generation point B becomes the maximum regeneration gap. Then, the target deceleration characteristic Gb is set by offset correction for shifting the reference target deceleration characteristic Ga read from the reference map setting unit 9a in the stroke increasing direction.

  On the other hand, when the detected actual MC pressure generation point C is too early than the design value MC pressure generation point A, as shown in FIG. As described above, the target deceleration characteristic Gc is set by offset correction for shifting the reference target deceleration characteristic Ga read from the reference map setting unit 9a in the stroke decreasing direction.

As described above, in the first embodiment, the reference target deceleration characteristic Ga is stored and set in advance, and the target deceleration characteristic Gb and the target deceleration characteristic Gc are obtained by offset correction that shifts the reference target deceleration characteristic Ga in the stroke direction. A configuration to set was adopted.
With this configuration, after the actual MC pressure generation point is determined so that the amount of braking is maximized, a characteristic curve that passes this determined point is created for each actual MC pressure generation point, or the actual MC pressure generation point There is no need for troublesome processing such as creating each time.
Therefore, the target deceleration characteristic that eliminates the influence of the clearance change at the actual MC pressure generation point can be set by a simple process of offset correction of the reference target deceleration characteristic Ga.

[Clearance estimation effect]
If there is a change in the clearance amount between the brake pad 41 and the rotor 42, the actual MC pressure generation point deviates from the design value MC pressure generation point. For this reason, when pursuing an appropriate setting of the target deceleration characteristic, it is necessary to accurately estimate the change in the clearance amount. Hereinafter, the clearance estimation effect reflecting this will be described.

When the brake is operated, in the flowchart of FIG. In step S1, the lateral G-sensitive clearance, which is a change (increase) in the clearance amount due to the lateral G effect, is estimated using the size of the lateral G and the clearance amount map shown in FIG. In step S2, the prefill clearance, which is a change amount (decrease amount) of the clearance amount according to the approach state of the brake pad 41 and the rotor 42, is learned and estimated during the prefill control intervention. In step S3, when it is determined that it is raining, the rain detection clearance which is a change amount (decrease amount) of the clearance amount according to the formation of the water film is learned and estimated. In step S4, the actual MC pressure generation point is estimated based on the clearance design value and the clearance estimated in steps S1 to S3.
Hereinafter, each event in which the clearance amount between the brake pad 41 and the rotor 42 changes will be described.

(a) When the lateral G is generated When the lateral G is large and the lateral G is large, the brake pad 41 is knocked back (the rotor 42 is tilted by a minute amount to widen the brake pad 41 and increase the clearance with the brake pad 41). This increases the amount of liquid consumed.
Also, when the lateral G is large, the rotor 42 has a face-center blur (a phenomenon in which the clearance between the brake pad 41 and the rotor 42 increases due to the displacement of the face center axis of the rotor 42 to widen the brake pad 41 during rotation). The amount of liquid consumed increases.
On the other hand, according to the size of the lateral G, a clearance increase amount between the brake pad 41 and the rotor 42 is learned and estimated, and an increasing amount of liquid consumption is predicted. Then, using the clearance amount map shown in FIG. 5, the lateral G-sensitive clearance (= correction stroke amount) is determined according to the size of the lateral G, and the stroke position where the generation of the regenerative braking force is started is corrected.
Therefore, at the time of turning braking, regardless of the size of the lateral G, the target deceleration characteristic map is corrected to an appropriate map that is added at the actual MC pressure generation point and becomes the maximum value of the target braking force (= regenerative gap). In particular, when the lateral G is large, the pedal feel discomfort due to the stepped feeling that the deceleration does not change even if the pedal stroke is increased is eliminated.

(b) Pre-fill control intervention When the driver depresses the brake pedal 11, if pre-fill control is involved, a predetermined hydraulic pressure is applied to each wheel cylinder 4FL, 4FR, 4RL, 4RR during the loss stroke before the MC pressure is generated. Supplied. Thus, the prefill control intervention fills the brake fluid in advance and closes the clearance between the brake pad 41 and the rotor 42, so the amount of liquid consumed during brake operation is reduced.
On the other hand, the clearance reduction amount between the brake pad 41 and the rotor 42 is learned / estimated according to the filling amount of the brake fluid, and the decreasing fluid consumption amount is predicted. Then, at the time of prefill control intervention, a prefill clearance (= correction stroke amount) is determined according to the approach state between the brake pad 41 and the rotor 42, and the stroke position at which the generation of the regenerative braking force is started is corrected.
Therefore, at the time of brake operation by the prefill control intervention, the target deceleration characteristic map is added at the actual MC pressure generation point and becomes the maximum value of the target braking force (= regenerative gap) regardless of the approach state of the brake pad 41 and the rotor 42. It is corrected to an appropriate map.

(c) In case of rain On rainy days, water adheres to the surfaces of the brake pad 41 and the rotor 42, and the brake pad 41 is attracted to the rotor 42 by a water film forming action when the rotor rotates. For this reason, since the clearance between the brake pad 41 and the rotor 42 is reduced compared with the case where there is no adhesion of water, the amount of liquid consumption is reduced.
On the other hand, the amount of liquid consumption that is reduced by the occurrence of wheel cylinder pressure due to water adhering to the surfaces of the brake pad 41 and the rotor 42 is predicted. In addition, if it is detected that it is raining, the rain detection clearance (= correction stroke amount) is determined from the predicted change in the amount of consumed liquid, and the stroke position where the generation of regenerative braking force is started is determined. to correct.
Therefore, when braking in rainy weather, regardless of the water film formation between the brake pad 41 and the rotor 42, the target deceleration characteristic map is added at the actual MC pressure generation point, and the maximum value of the target braking force (= regeneration) It is corrected to an appropriate map that becomes a gap).

Next, the effect will be described.
In the hybrid vehicle brake control device of the first embodiment, the following effects can be obtained.

(1) a master cylinder 13 that generates a master cylinder pressure corresponding to the brake operation;
Wheel cylinders 4FL, 4FR, 4RL, 4RR which are provided on each of the front and rear wheels and apply a hydraulic braking force to each wheel according to the wheel cylinder pressure;
Hydraulic pumps 22 and 22 that are interposed between the master cylinder 13 and the wheel cylinders 4FL, 4FR, 4RL, and 4RR and are driven by a pump motor (VDC motor 21), and the pump motor (VDC motor 21). ) Brake hydraulic actuator (VDC brake) having differential pressure valves (first M / C cut solenoid valve 25, second M / C cut solenoid valve 26) for controlling the differential pressure between the wheel cylinder pressure and the master cylinder pressure Hydraulic unit 2),
Regenerative braking force control means (motor controller 8) connected to the driving electric motor 5 connected to the drive wheel and controlling the regenerative braking force generated by the driving electric motor 5;
The braking target value (target deceleration) calculated using the brake pedal stroke detection value and the braking target value characteristic map at the time of the brake operation is calculated based on the basic hydraulic pressure component based on the master cylinder pressure, the regenerative component based on the regenerative braking force, and the Regenerative cooperative brake control means (regenerative cooperative brake control unit 9d, FIG. 7) that performs control to achieve the sum of at least one of the additional pressures applied by the brake hydraulic pressure actuator (VDC brake hydraulic pressure unit 2). When,
Clearance estimation means (clearance estimation unit 9e, steps S1 to S4 in FIG. 4) for estimating the clearance amount between the brake pads 41 of the wheel cylinders 4FL, 4FR, 4RL, 4RR and the rotor 42;
When the estimated clearance changes with respect to the design value, the braking target value at the actual master cylinder pressure generation stroke (actual MC pressure generation point A), which is the brake pedal stroke position at which the generation of the master cylinder pressure is started. The braking target value characteristics (target deceleration characteristics Gb, Gc) according to the amount of change in the clearance from the design value so that (target deceleration) becomes the maximum value for additional braking or within the allowable range. Braking target value characteristic setting means (target deceleration characteristic map setting unit 9b, steps S5 to S8 in FIG. 4),
Is provided.
For this reason, at the time of regenerative cooperative brake control, even if a clearance change occurs between the brake pad 41 and the rotor 42, it is possible to achieve good brake feeling and securing of regenerative energy.

(2) The stroke position at which the brake pedal stroke amount reaches the design value loss stroke is defined as the design value master cylinder pressure generation point A, and the braking target value (target deceleration) at the design value master cylinder pressure generation point A is added to the brake. Reference braking target value characteristic setting means (reference map setting unit) that presets a reference braking target value characteristic (reference target deceleration characteristic Ga) that changes smoothly with respect to a stroke change, with a maximum value (regenerative gap) of minutes 9a), and
The braking target value characteristic setting means (target deceleration characteristic map setting unit 9b, steps S5 to S8 in FIG. 4) determines the reference braking target value according to the magnitude relationship between the design value of the clearance amount and the estimated clearance amount. The braking target value characteristics (target deceleration characteristics Gb, Gc) are set by correcting the characteristics (reference target deceleration characteristics Ga).
For this reason, in addition to the effect of (1) above, the setting of the braking target value characteristics (target deceleration characteristics Gb, Gc) that eliminate the influence of the clearance change between the brake pad 41 and the rotor 42 is set as the reference braking target value characteristics. This can be performed by a simple process of correcting (reference target deceleration characteristic Ga).

(3) The braking target value characteristic setting means (target deceleration characteristic map setting unit 9b, steps S5 to S8 in FIG. 4) is provided between the brake pads 41 and the rotor 42 of the wheel cylinders 4FL, 4FR, 4RL, 4RR. When the clearance amount is smaller than the design value, the regenerative braking force generation start point of the reference braking target value characteristic (reference target deceleration characteristic Ga) is offset-corrected in the direction in which the pedal stroke becomes shorter, and the braking target value characteristic (target The deceleration characteristic Gc) is set (step S6 in FIG. 4, FIG. 13).
For this reason, in addition to the effect of (2) above, the actual clearance amount is smaller than the design value while maintaining pedal feeling with the reference braking target value characteristic (reference target deceleration characteristic Ga) during regenerative cooperative brake control. In this case, the braking target value characteristic (target deceleration characteristic Gc) can be corrected.

(4) The braking target value characteristic setting means (target deceleration characteristic map setting unit 9b, steps S5 to S8 in FIG. 4) is provided between the brake pads 41 and the rotor 42 of the wheel cylinders 4FL, 4FR, 4RL, 4RR. When the clearance amount is larger than the design value, the regenerative braking force generation start point of the reference braking target value characteristic (reference target deceleration characteristic Ga) is offset-corrected in the direction in which the pedal stroke becomes longer, and the braking target value characteristic (target The deceleration characteristic Gb) is set (step S8 in FIG. 4, FIG. 14).
For this reason, in addition to the effect of (2) above, the actual clearance value is larger than the design value while maintaining pedal feeling based on the reference braking target value characteristic (reference target deceleration characteristic Ga) during regenerative cooperative brake control. In this case, the braking target value characteristic (target deceleration characteristic Gb) can be corrected.

(5) The clearance estimating means (clearance estimating unit 9e) is configured to determine a clearance amount (lateral G sensitivity) between the brake pads 41 of the wheel cylinders 4FL, 4FR, 4RL, and 4RR and the rotor 42 according to the magnitude of the lateral acceleration. (Clearance) is estimated (step S1 in FIG. 4).
For this reason, in addition to the effects (1) to (4) described above, during turning braking, the clearance between the brake pad 41 and the rotor 42 changes to the enlargement side by pushing the brake pad 41 wider as the lateral acceleration increases. Correspondingly, the clearance change can be estimated with high accuracy.

(6) The clearance estimating means (clearance estimating unit 9e) is a clearance between the brake pad 41 and the rotor 42 during the prefill control intervention in which the wheel cylinders 4FL, 4FR, 4RL and 4RR are prefilled with brake fluid. The amount (prefill clearance) is estimated (step S2 in FIG. 4).
For this reason, in addition to the effects (1) to (4) described above, the clearance between the brake pad 41 and the rotor 42 is reduced when the prefill control intervention is performed. Can be estimated.

(7) The clearance estimating means (clearance estimating unit 9e) estimates a clearance amount (rainy detection clearance) between the brake pads 41 of the wheel cylinders 4FL, 4FR, 4RL, and 4RR and the rotor 42 in rainy weather ( Step S3 in FIG.
For this reason, in addition to the effects (1) to (4) above, a water film is formed by water adhering to the surface during rain, so that the clearance between the brake pad 41 and the rotor 42 changes to the reduction side. It is possible to estimate the clearance change with high accuracy in response to the phenomenon.

  The second embodiment is an example in which, when setting the target deceleration characteristics Gb, Gc, the correction method from the reference target deceleration characteristics Ga is changed.

First, the configuration will be described.
Also in the second embodiment, the target deceleration characteristic map setting process is performed using the flowchart of the first embodiment shown in FIG. However, the method of setting the target deceleration characteristic map in step S6 and step S8 is different.

  In step S6, following the determination that the actual MC pressure generation point <design value−α in step S5, the point at which the regenerative braking force of the reference target deceleration characteristic becomes the maximum value is offset in the direction in which the pedal stroke becomes shorter. Then, the target deceleration characteristic map is set by correcting in the direction of increasing the inclination so as to connect the corrected point and the regenerative braking force generation start point of the reference target deceleration characteristic (FIG. 15). From step S6, the process proceeds to return.

In step S8, following the determination that the actual MC pressure generation point> design value + α in step S7, the point at which the regenerative braking force of the reference target deceleration characteristic becomes the maximum value is offset-corrected in the direction in which the pedal stroke becomes longer. Then, the target deceleration characteristic map is set by correcting the inclination so that the inclination decreases so as to connect the corrected point and the regenerative braking force generation start point of the reference target deceleration characteristic (FIG. 16). From step S8, the process proceeds to return.
Since other configurations are the same as those of the first embodiment, illustration and description thereof are omitted.

Next, a method for setting a target deceleration characteristic by inclination correction in the second embodiment will be described.
First, the reference map setting unit 9a determines the design value MC pressure generation point A at the brake pedal stroke position based on the design value loss stroke. Then, a reference map based on the reference target deceleration characteristic Ga set so as to become the maximum value of the target braking force added (= regenerative gap) at the design value MC pressure generation point A is set in advance. Then, in the target deceleration characteristic map setting unit 9b, based on the estimation of the clearance between the brake pad 41 and the rotor 42 in the clearance estimation unit 9e, the brake pedal stroke position where the master cylinder pressure is actually generated during the brake operation. The actual MC pressure generation points B and C are estimated.

  When the estimated actual MC pressure generation point B is later than the design value MC pressure generation point A, as shown in FIG. 16, the additional braking amount at the actual MC pressure generation point B becomes the maximum regeneration gap. Then, offset correction is performed to shift the reference target deceleration characteristic Ga read from the reference map setting unit 9a in the stroke increasing direction. In addition, the target deceleration characteristic Gb2 is set by correcting in the direction of decreasing the slope so as to connect the corrected point and the regenerative braking force generation start point of the reference target deceleration characteristic Ga.

On the other hand, when the detected actual MC pressure generation point C is too early than the design value MC pressure generation point A, as shown in FIG. As described above, the offset correction for shifting the reference target deceleration characteristic Ga read from the reference map setting unit 9a in the stroke decreasing direction is performed. In addition, the target deceleration characteristic Gc2 is set by correcting in a direction in which the inclination increases so as to connect the corrected point and the regenerative braking force generation start point of the reference target deceleration characteristic Ga.
Since other operations are the same as those in the first embodiment, description thereof is omitted.

Next, the effect will be described.
In the hybrid vehicle brake control apparatus according to the second embodiment, the following effects can be obtained.

(8) The braking target value characteristic setting means (target deceleration characteristic map setting unit 9b, steps S5 to S8 in FIG. 4) is provided between the brake pads 41 and the rotor 42 of the wheel cylinders 4FL, 4FR, 4RL, 4RR. When the clearance amount is smaller than the design value, the point at which the regenerative braking force of the reference braking target value characteristic (reference target deceleration characteristic Ga) becomes the maximum value is offset corrected in the direction of shortening the pedal stroke, and the corrected point And the reference braking target value characteristic (reference target deceleration characteristic Ga) is corrected so that the inclination increases so as to connect the regenerative braking force generation start point, and the braking target value characteristic (target deceleration characteristic Gc2) is set ( Step S6 in FIG. 4, FIG. 15).
For this reason, in addition to the effect of (2) above, it is appropriate when the actual value of the clearance is smaller than the design value while maintaining the regenerative braking force generation start timing at the same pedal stroke during regenerative cooperative brake control. Can be corrected to a desired braking target value characteristic (target deceleration characteristic Gc2).

(9) The braking target value characteristic setting means (target deceleration characteristic map setting unit 9b, steps S5 to S8 in FIG. 4) is provided between the brake pads 41 of the wheel cylinders 4FL, 4FR, 4RL, 4RR and the rotor 42. When the clearance amount is smaller than the design value, the point where the regenerative braking force of the reference braking target value characteristic (reference target deceleration characteristic Ga) becomes the maximum value is offset-corrected in the direction in which the pedal stroke becomes longer, and the corrected point The braking target value characteristic (target deceleration characteristic Gc2) is set by correcting the inclination so that the inclination decreases so as to connect the regenerative braking force generation start point of the reference braking target value characteristic (reference target deceleration characteristic Ga) ( Step S8 in FIG. 4, FIG. 16).
Therefore, in addition to the effect of (2) above, it is appropriate when the actual value of the clearance amount is larger than the design value while maintaining the regenerative braking force generation start timing at the same pedal stroke during regenerative cooperative brake control. Can be corrected to a desired braking target value characteristic (target deceleration characteristic Gb2).

  As mentioned above, although the brake control apparatus of the electric vehicle of this invention has been demonstrated based on Example 1 and Example 2, it is not restricted to these Examples about a concrete structure, Each of Claims Design changes and additions are permitted without departing from the scope of the claimed invention.

  In the first and second embodiments, the example in which the target deceleration map for the stroke is used as the braking target value characteristic setting means has been described. However, a target braking force map for the stroke, a driver required deceleration map for the stroke, a driver required braking force map for the stroke, and the like may be used. Furthermore, the target deceleration characteristic with respect to the stroke may be set by an arithmetic expression, and the target deceleration may be obtained sequentially by the calculated value. In other words, any means for setting a braking target value characteristic that reflects the braking performance requested by the driver that appears in the brake pedal stroke during brake operation is not limited to an example using a map, but a characteristic setting using a braking target value characteristic calculation formula Or an example of applying a correction method.

  In the first and second embodiments, as the braking target value characteristic setting means, with respect to the stroke change, the target deceleration at the detected actual MC pressure generation point becomes the maximum value (regenerative gap) for the additional braking. An example of setting the target deceleration characteristics that change smoothly is shown. However, the target deceleration at the detected actual MC pressure generation point changes smoothly with respect to the stroke change so that the deviation from the maximum value of the additional braking (regenerative gap) falls within the allowable range. The target deceleration characteristic to be set may be set.

  In the first embodiment, when setting the target deceleration characteristic, an example in which only the offset correction of the reference target deceleration characteristic with respect to the stroke is set is shown. In the second embodiment, when setting the target deceleration characteristics, an example is shown in which both the offset correction and the gradient correction of the reference target deceleration characteristics for the stroke are set. However, an example of setting using only the gradient correction of the reference target deceleration characteristic with respect to the stroke may be used.

  In the first and second embodiments, the target deceleration characteristics are set using the reference target deceleration characteristics for the stroke. However, an example may be used in which the target deceleration characteristic is created using the detected target deceleration at the actual MC pressure generation point as the maximum value range for the additional braking without using the reference target deceleration characteristic. Further, the actual MC pressure generation point may be learned and corrected based on a plurality of data obtained from the brake braking experience so as to cope with variations due to aging and brake fluid temperature. It should be noted that the target deceleration characteristic map may be set at the time of manufacturing offline check, or at the time of brake operation immediately after the ignition key switch is turned on.

  In the first and second embodiments, as an event in which the clearance between the brake pad 41 and the rotor 42 changes, an example is shown when the lateral G occurs, during prefill control intervention, or in the rain. However, events other than those shown in the first and second embodiments may be added as events in which the clearance between the brake pad and the rotor changes.

  In Examples 1 and 2, the example using the VDC brake fluid pressure unit 2 shown in FIG. 2 as a brake fluid pressure actuator was shown. However, any brake hydraulic actuator may be used as long as it has a hydraulic pump driven by a VDC motor and a differential pressure valve that controls the differential pressure between the wheel cylinder pressure and the master cylinder pressure when the pump motor is operated. .

  In the first and second embodiments, the brake control device of the present invention is applied to a front-wheel drive hybrid vehicle. However, if the vehicle is an electric vehicle such as a rear-wheel drive hybrid vehicle, an electric vehicle, a fuel cell vehicle, etc. and performs regenerative cooperative brake control using a hydraulic braking force and a regenerative braking force, the brake control device of the present invention is applied. can do.

1 Brake fluid pressure generator 2 VDC brake fluid pressure unit (brake fluid pressure actuator)
21 VDC motor (pump motor)
22 Hydraulic pump 25 1st M / C cut solenoid valve (Differential pressure valve)
26 2nd M / C cut solenoid valve (Differential pressure valve)
3 Stroke sensor 4FL Left front wheel wheel cylinder 4FR Right front wheel wheel cylinder 4RL Left rear wheel wheel cylinder 4RR Right rear wheel wheel cylinder 41 Brake pad 42 Rotor 5 Electric motor 61 for traveling Primary hydraulic pipe 62 Secondary hydraulic pipe 63 Left front wheel hydraulic pipe 64 Right Front wheel hydraulic pipe 65 Left rear wheel hydraulic pipe 66 Right rear wheel hydraulic pipe 7 Brake controller 8 Motor controller (regenerative braking force control means)
9 Integrated controller 9a Reference map setting unit (reference braking target value characteristic setting means)
9b Target deceleration characteristic map setting unit (braking target value characteristic setting means)
9c Target deceleration calculation unit (regenerative cooperative brake control means)
9d Regenerative cooperative brake control unit (Regenerative cooperative brake control means)
9e Clearance estimation part (clearance estimation means)
91 Battery controller 92 Vehicle speed sensor 93 Brake switch 94 Lateral acceleration sensor 95 Prefill controller 96 Raindrop sensor

Claims (9)

A master cylinder that generates a master cylinder pressure according to the brake operation;
A wheel cylinder that is provided on each of the front and rear wheels and applies a hydraulic braking force to each wheel according to the wheel cylinder pressure;
A hydraulic pump interposed between the master cylinder and the wheel cylinder and driven by a pump motor; and a differential pressure valve for controlling a differential pressure between the wheel cylinder pressure and the master cylinder pressure when the pump motor is operated; A brake hydraulic actuator having,
Regenerative braking force control means for controlling a regenerative braking force generated by the traveling electric motor, connected to the traveling electric motor coupled to the drive wheel;
The braking target value calculated by using the brake pedal stroke detection value and the braking target value characteristic map at the time of the brake operation is determined by the basic hydraulic pressure component by the master cylinder pressure, the regenerative component by the regenerative braking force, and the brake hydraulic pressure actuator. Regenerative cooperative brake control means for performing control to achieve the sum of the additional braking amount by at least one of the pressurizing components,
Clearance estimation means for estimating a clearance amount between a brake pad of the wheel cylinder and the rotor;
When the estimated clearance changes with respect to the design value, the braking target value at the actual master cylinder pressure generation stroke, which is the brake pedal stroke position at which the generation of the master cylinder pressure is started, is the maximum value for the additional braking. Braking target value characteristic setting means for setting a braking target value characteristic according to a clearance change amount from the design value so as to be within an allowable range,
A brake control device for an electric vehicle, comprising: In the brake control device for an electric vehicle according to claim 1,
The stroke position at which the brake pedal stroke amount reaches the design value loss stroke is defined as the design value master cylinder pressure generation point, and the braking target value at the design value master cylinder pressure generation point is set to the maximum value for the above-described additional braking. And a reference braking target value characteristic setting means for presetting a reference braking target value characteristic that changes smoothly in advance,
The braking target value characteristic setting means sets the braking target value characteristic by correcting the reference braking target value characteristic according to a magnitude relationship between a design value of a clearance amount and an estimated clearance amount. Brake control device for electric vehicles. In the brake control device for an electric vehicle according to claim 2,
When the clearance amount between the brake pad of the wheel cylinder and the rotor is smaller than a design value, the braking target value characteristic setting means shortens the pedal stroke at the regenerative braking force generation start point of the reference braking target value characteristic. A brake control device for an electric vehicle, wherein a braking target value characteristic is set by correcting an offset in a direction. In the brake control device for an electric vehicle according to claim 2,
When the clearance amount between the brake pad of the wheel cylinder and the rotor is larger than a design value, the brake target value characteristic setting means has a longer pedal stroke than the regenerative braking force generation start point of the reference brake target value characteristic. A brake control device for an electric vehicle, wherein a braking target value characteristic is set by correcting an offset in a direction. In the brake control device for an electric vehicle according to claim 2,
The braking target value characteristic setting means determines the point at which the regenerative braking force of the reference braking target value characteristic becomes a maximum value when the clearance amount between the brake pad of the wheel cylinder and the rotor is smaller than a design value. The offset correction is performed in a direction in which the braking target value is shortened, and the braking target value characteristic is set by correcting in the direction in which the inclination increases so as to connect the corrected point and the regenerative braking force generation start point of the reference braking target value characteristic. Electric vehicle brake control device. In the brake control device for an electric vehicle according to claim 2,
The braking target value characteristic setting means determines a point at which the regenerative braking force of the reference braking target value characteristic becomes a maximum value when the clearance amount between the brake pad of the wheel cylinder and the rotor is larger than a design value. The offset correction is performed in a direction in which the braking target value becomes longer, and the braking target value characteristic is set by correcting in a direction in which the inclination decreases so as to connect the corrected point and the regenerative braking force generation start point of the reference braking target value characteristic. Electric vehicle brake control device. In the brake control device for an electric vehicle according to any one of claims 1 to 6,
The said clearance estimation means estimates the clearance amount between the brake pad of the said wheel cylinder and a rotor according to the magnitude | size of a lateral acceleration. The brake control apparatus of the electric vehicle characterized by the above-mentioned. In the brake control device for an electric vehicle according to any one of claims 1 to 6,
The brake control device for an electric vehicle, wherein the clearance estimation means estimates a clearance amount between a brake pad and a rotor at the time of prefill control intervention in which the wheel cylinder is prefilled with brake fluid. In the brake control device for an electric vehicle according to any one of claims 1 to 6,
The said clearance estimation means estimates the clearance amount between the brake pad of the said wheel cylinder and rotor at the time of rainy weather. The brake control apparatus of the electric vehicle characterized by the above-mentioned.