JP2015093586A - Vehicular brake control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular brake control apparatus capable of suppressing step-on force in a case where actual deceleration is deviated from target deceleration and a master cylinder pressure instruction value is corrected for suppressing the deviation, when performing regenerative cooperation control.SOLUTION: A regenerative cooperation control part 200, which executes regenerative cooperation control for controlling friction braking torque and regenerative braking torque, includes a master cylinder pressure instruction correction control part 231 for determining, when an instruction value of master cylinder pressure Pmc is corrected in a direction of narrowing down a deviation in a case where actual deceleration of a vehicle has the deviation from target deceleration based on required-braking torque of a driver in regenerative cooperation control, whether a step-on force variation amount (a pre-post-correction input rod reactive-force variation amount ΔFir_Lmt) is within a predetermined permissible value (a permissible input rod variation amount Fir_Lmt) by the correction of the instruction value, and decreasing the correction amount of the instruction value, if the variation amount is determined to exceed the permissible value.

Description

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

2. Description of the Related Art Conventionally, a vehicular brake control device that generates a driver's required deceleration by cooperatively operating a regenerative braking device and a friction (hydraulic pressure) braking device is known (see, for example, Patent Document 1).
In this prior art, the input rod operated by the driver is arranged at a position where the input to the input rod and the resultant force of the master cylinder pressure and the reaction force of the return spring are balanced, as shown in the following equation (01). The
Input rod input (Fi)
= Master cylinder pressure (Pmc) × input rod area (Ai) + spring constant of return spring (K) × spring stroke amount (Δx) (01)
In this prior art, the target piston stroke is calculated with respect to the input rod stroke (Xi), and the booster thrust (Fb) is controlled so that the piston stroke (Xb) becomes the target piston stroke.

JP 2007-112426 A

However, in the above-described prior art, there may be a difference between the actual characteristic and the control characteristic of the friction braking torque with respect to the piston stroke amount due to factors such as the vehicle speed and temperature. In this case, the actual total braking torque varies with respect to the target braking torque.
And, due to the deviation between the actual characteristic and the control characteristic of the friction braking torque, the master cylinder pressure fluctuates when the total braking torque is adjusted by adjusting the booster thrust from moment to moment, This appears as a change in the driver's brake pedal force.

  The present invention has been made paying attention to the above problem, and when regenerative cooperative control is performed, the actual deceleration deviates from the target deceleration, and the master cylinder pressure command value is corrected to suppress this deviation. Another object of the present invention is to provide a vehicular braking control device capable of suppressing the occurrence of pedaling force fluctuations.

In order to achieve the above object, a vehicle brake control device of the present invention includes:
A vehicle including a regenerative cooperative control device that executes regenerative cooperative control for controlling the friction braking torque and the regenerative braking torque so that a total braking torque including the friction braking torque and the regenerative braking torque becomes a driver's required braking torque. Brake control device for
In the regenerative cooperative control, the regenerative cooperative control device instructs the master cylinder pressure to narrow the deviation when the actual deceleration of the vehicle deviates from a target deceleration corresponding to the driver's required braking torque. When correcting the value, it is determined whether or not the pedaling force fluctuation amount is within a preset allowable value by correcting the command value. If the value exceeds the allowable value, the correction value of the command value is decreased. A vehicular braking control device comprising a master cylinder pressure command correction limiting unit is provided.

In the vehicular braking control apparatus of the present invention, the master cylinder pressure command correction limiting unit performs the pedaling force when correcting the master cylinder pressure according to the actual deceleration deviating from the target deceleration during the regenerative cooperative control. When the amount of fluctuation exceeds the allowable value, the amount of correction is decreased.
Due to the decrease in the correction amount, the amount of change in the master cylinder pressure due to the correction is also reduced, and the pedaling force fluctuation can be suppressed.

1 is an overall system diagram showing a configuration of a hybrid vehicle to which a vehicle brake control device of Embodiment 1 is applied. 1 is an overall configuration diagram of a brake device used in a vehicle brake control device according to a first embodiment. It is a block diagram which simplifies and shows the structure which performs the regeneration cooperation control in the brake control apparatus for vehicles of Embodiment 1. 3 is a flowchart showing an overall flow of processing for calculating a master cylinder pressure command value in regenerative cooperative control in the vehicle brake control device of the first embodiment. It is a flowchart which shows the detail of the process of step S19 of the flowchart of FIG. It is a flowchart which shows the detail of the process of step S25, S26 of the flowchart of FIG. It is a flowchart which shows the detail of the process of step S32 of the flowchart of FIG. FIG. 6 is a reaction force limit value characteristic diagram showing a map used for calculating an input rod reaction force difference limit value in step S29 of the flowchart of FIG. 5. 3 is a time chart showing an operation example of a comparative example for comparison with the vehicle brake control device of the first embodiment. 5 is a time chart showing changes in pedaling force when the master cylinder pressure is corrected in a comparative example for comparison with the vehicle brake control device of the first embodiment. 3 is a time chart illustrating an operation example of the vehicle brake control device according to the first embodiment.

Hereinafter, the best mode for realizing the vehicle brake control device of the present invention will be described based on the first embodiment shown in the drawings.
First, the configuration of the vehicle brake control device of the first embodiment will be described.
The configuration of the hybrid vehicle provided with the vehicle brake control device of the first embodiment is “overall configuration” “control system” “brake device configuration” [configuration and operation of master cylinder pressure control mechanism] [execution of regenerative cooperative control] The configuration will be described separately.

[overall structure]
FIG. 1 is an overall system diagram showing the hybrid vehicle.
As shown in FIG. 1, the drive system of this hybrid vehicle includes an engine E, a first clutch CL1, a motor generator (regenerative braking device) MG, a second clutch CL2, an automatic transmission AT, and a propeller shaft PS. And a differential DF, a left drive shaft DSL, a right drive shaft DSR, a left rear wheel RL, and a right rear wheel RR. In addition, left driven wheels FL and right front wheels FR are provided as driven wheels.

  The engine E is, for example, a gasoline engine, and the valve opening degree of the throttle valve and the like are controlled based on a control command from an engine controller 101 described later. The engine output shaft is provided with a flywheel FW.

  The first clutch CL1 is a clutch interposed between the engine E and the motor generator MG. The first clutch CL1 is operated by a control hydraulic pressure generated by the first clutch hydraulic unit 106 based on a control command from a first clutch controller 105, which will be described later, and the engagement / disengagement including slip engagement is controlled. Specifically, the first clutch CL1 is a normally closed dry clutch that is fully engaged by the urging force of the leaf spring when not controlled. When a release command is output to the first clutch CL1, the hydraulic pressure corresponding to the transmission torque capacity command is supplied to the piston to make a stroke, and the transmission torque capacity corresponding to the stroke amount is set. When a stroke exceeding a predetermined value is performed, contact between the clutch plates is cut off and released. Further, in order to reduce friction loss when the clutch is released, the piston is further stroked by a predetermined amount by increasing the hydraulic pressure applied to the piston even after the clutch plate is disconnected.

  On the other hand, when the first clutch CL1 is engaged from the released state, the hydraulic pressure applied to the piston is gradually lowered. Then, the piston starts a stroke, and the clutch plate starts to come into contact when the piston strokes a predetermined amount (corresponding to backlash). Incidentally, whether or not the clutch plate is in contact can be determined by whether or not the engine speed Ne has started to increase. Thereafter, the lower the hydraulic pressure acting on the piston, the higher the transmission torque capacity.

Motor generator MG is a synchronous motor generator in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator. The motor generator MG is controlled by applying a three-phase alternating current formed by the inverter 103 based on a control command from a motor controller 102 described later.
In addition, motor generator MG can operate as an electric motor (regenerative braking device) that rotates by receiving power supplied from battery 104 (hereinafter, this state is referred to as “power running”). Furthermore, when the rotor is rotated by an external force, the motor generator MG can function as a generator that generates an electromotive force at both ends of the stator coil to charge the battery 104 (hereinafter, this operation state is referred to as “operating state”). Called "regeneration"). Note that the rotor of the motor generator MG is connected to the input shaft of the automatic transmission AT via a damper (not shown).

  The second clutch CL2 is a clutch interposed between the motor generator MG and the left and right rear wheels RL and RR. The second clutch CL2 is controlled to be engaged and disengaged including slip engagement by the control hydraulic pressure generated by the second clutch hydraulic unit 108 based on a control command from the AT controller 107 described later.

  The automatic transmission AT is a transmission that automatically switches stepped gear ratios such as forward five speeds and reverse first speeds according to the vehicle speed Vw, the accelerator opening APO, and the like. In the first embodiment, the second clutch CL2 is not newly added as a dedicated clutch, and some of the frictional engagement elements among a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission AT are included. The element is diverted. Further, the second clutch CL2 may be provided independently between the motor generator MG and the automatic transmission AT.

  The output shaft of the automatic transmission AT is connected to the left and right rear wheels RL and RR via a propeller shaft PS, a differential DF, a left drive shaft DSL, and a right drive shaft DSR as vehicle drive shafts. The first clutch CL1 and the second clutch CL2 are, for example, wet multi-plate clutches that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid.

The drive system of this hybrid vehicle has three travel modes according to the engaged / released state of the first clutch CL1.
The first travel mode is abbreviated as an “electric vehicle travel mode” (hereinafter referred to as “EV travel mode”) as a motor use travel mode in which the first clutch CL1 is disengaged and travels using only the power of the motor generator MG as a power source. ).
The second travel mode is an engine use travel mode (hereinafter abbreviated as “HEV travel mode”) in which the first clutch CL1 is engaged and the engine E is included in the power source.

  The third travel mode is an engine use slip travel mode (hereinafter referred to as “WSC travel mode”) in which the second clutch CL2 is slip-controlled while the first clutch CL1 is engaged, and the engine E is included in the power source. Abbreviated). This WSC mode is a mode in which creep running can be achieved particularly when the battery SOC is low or the engine water temperature is low. When transitioning from the EV travel mode to the HEV travel mode, the first clutch CL1 is engaged and the engine is started using the torque of the motor generator MG.

Further, in the “HEV travel mode”, three travel modes of “engine travel mode”, “motor assist travel mode”, and “travel power generation mode” are set.
In the “engine running mode”, the left and right rear wheels RL and RR as drive wheels are moved using only the engine E as a power source. In the “motor-assisted travel mode”, the left and right rear wheels RL and RR as drive wheels are moved using the engine E and the motor generator MG as power sources. In the “running power generation mode”, the engine generator MG is caused to function as a power generator while the left and right rear wheels RL and RR as drive wheels are moved using the engine E as a power source.

During constant speed operation or acceleration operation, motor generator MG is operated as a generator using the power of engine E. Further, during deceleration operation, braking energy is regenerated and electric power is generated by the motor generator MG, which is used for charging the battery 104.
Further, as a further mode, there is a power generation mode in which the motor generator MG is operated as a generator using the power of the engine E when the vehicle is stopped.

[Control system]
Next, the control system of the hybrid vehicle will be described.
As shown in FIG. 1, the hybrid vehicle control system includes an engine controller 101, a motor controller 102, an inverter 103, a battery 104, a first clutch controller 105, a first clutch hydraulic unit 106, and an AT controller 107. And the second clutch hydraulic unit 108, the brake device 1, and an integrated controller (regenerative cooperative control device) 110. The engine controller 101, the motor controller 102, the first clutch controller 105, the AT controller 107, the brake device 1, and the integrated controller 110 are connected via a CAN communication line 111 that can exchange information with each other. Has been.

  The engine controller 101 inputs engine speed information from the engine speed sensor 112 and controls an engine operating point (Ne: engine speed, Te: engine torque) in accordance with a target engine torque command or the like from the integrated controller 110. Command to output. This command output is output, for example, to a throttle valve actuator (not shown). Information such as the engine speed Ne is supplied to the integrated controller 110 via the CAN communication line 111.

  The motor controller 102 inputs information from the resolver 113 that detects the rotor rotational position of the motor generator MG. Then, a command for controlling the motor operating point (Nm: motor generator rotational speed, Tm: motor generator torque) of motor generator MG is output to inverter 103 in accordance with a target motor generator torque command or the like from integrated controller 110. The motor controller 102 monitors the battery SOC indicating the state of charge of the battery 104. The battery SOC information is used as control information for the motor generator MG and supplied to the integrated controller 110 via the CAN communication line 111. Is done.

  The first clutch controller 105 inputs sensor information from the first clutch oil pressure sensor 114 and the first clutch stroke sensor 115. Then, in response to the first clutch control command from the integrated controller 110, a command for controlling the engagement / release of the first clutch CL1 is output to the first clutch hydraulic unit 106. Information on the first clutch stroke C1S is supplied to the integrated controller 110 via the CAN communication line 111.

  The AT controller 107 inputs sensor information from an accelerator opening sensor 116, a vehicle speed sensor 117, a second clutch hydraulic pressure sensor 118, and an inhibitor switch that outputs a signal corresponding to the position of the shift lever operated by the driver. In response to the second clutch control command from the integrated controller 110, a command for controlling the engagement / release of the second clutch CL2 is output to the second clutch hydraulic unit 108 in the AT hydraulic control valve. Information on the accelerator opening APO, the vehicle speed Vw, and the inhibitor switch is supplied to the integrated controller 110 via the CAN communication line 111.

  The brake device 1 applies a friction braking torque to each wheel according to the braking operation of the driver. Further, the friction braking torque is adjusted based on the regenerative cooperative control command from the integrated controller 110. The regeneration cooperative control will be described later.

  The integrated controller 110 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. The integrated controller 110 detects the motor rotation speed Nm, and the second clutch output rotation speed N2out. A second clutch output speed sensor 122 for detecting the second clutch torque, a second clutch torque sensor 123 for detecting the second clutch transmission torque capacity TCL2 (second clutch torque), and a wheel speed sensor 124 for detecting the wheel speeds of the four wheels. Each sensor information from the G sensor 125 that detects longitudinal acceleration and information obtained through the CAN communication line 111 are input.

  The integrated controller 110 controls the operation of the engine E based on the control command to the engine controller 101, the operation control of the motor generator MG based on the control command to the motor controller 102, and the first clutch CL1 based on the control command to the first clutch controller 105. Engagement / release control, engagement / release control of the second clutch CL2 by a control command to the AT controller 107, and operation control of the brake device 1 by a control command to the brake controller 109.

  The integrated controller 110 calculates the target deceleration with respect to the brake pedal depression amount of the driver, and gives priority to the regenerative braking torque over the calculated target deceleration. Energy recovery by regenerative braking is realized up to a higher and lower vehicle speed.

  On the other hand, the regenerative braking torque has an upper limit depending on the number of revolutions determined by the vehicle speed. Therefore, if the deceleration by the regenerative braking torque is insufficient for the target deceleration, regenerative cooperative control will compensate for the shortage with the friction braking torque. The command is output to the brake device 1.

[Configuration of brake device]
FIG. 2 is an overall configuration diagram of the brake device 1 used in the vehicle brake control device of the first embodiment. The brake device 1 includes a master cylinder 2, a reservoir tank RES, wheel cylinders 4a to 4d provided on each wheel, a master cylinder pressure control mechanism (brake booster) 5 provided connected to the master cylinder 2, and An input rod (input member) 6, a brake operation amount detection device 7, and a master cylinder pressure control device 8 that controls the master cylinder pressure control mechanism 5 are provided.

The input rod 6 makes a stroke (advance and retreat) together with the brake pedal BP, and increases or decreases the hydraulic pressure in the master cylinder 2 (hereinafter, master cylinder pressure Pmc). The master cylinder pressure control mechanism 5 and the master cylinder pressure control device 8 stroke the primary piston (assist member) 2b of the master cylinder 2 to increase or decrease the master cylinder pressure Pmc.
Hereinafter, for the sake of explanation, the x axis is set in the axial direction of the master cylinder 2, the brake pedal BP side is set as the negative direction, and the stepping stroke direction is set as the positive direction.

  The master cylinder 2 is a so-called tandem type, and has a primary piston 2b and a secondary piston 2c in the cylinder 2a. A primary hydraulic chamber 2d as a first hydraulic chamber is formed between the inner peripheral surface of the cylinder 2a and the surface of the primary piston 2b on the x axis positive direction side and the surface of the secondary piston 2c on the x axis negative direction side. Has been. A secondary fluid chamber 2e as a second fluid pressure chamber is formed between the inner peripheral surface of the cylinder 2a and the surface of the secondary piston 2c on the x-axis positive direction side.

The primary hydraulic chamber 2 d is connected so as to be able to communicate with the primary circuit 10, and the secondary hydraulic chamber 2 e is connected so as to be able to communicate with the secondary circuit 20. The volume of the primary hydraulic chamber 2d changes as the primary piston 2b and the secondary piston 2c stroke in the cylinder 2a. In the primary hydraulic pressure chamber 2d, a return spring 2f that urges the primary piston 2b in the negative x-axis direction is installed. The volume of the secondary liquid chamber 2e changes as the secondary piston 2c strokes in the cylinder 2a. In the secondary liquid chamber 2e, a return spring 2g that urges the secondary piston 2c to the x-axis negative direction side is installed.
The primary circuit 10 and the secondary circuit 20 are provided with a hydraulic pressure control unit 100 including various valves, motor pumps, reservoirs and the like that can independently control each wheel cylinder pressure for performing ABS control and the like. ing.

  The primary circuit 10 is provided with a primary hydraulic pressure sensor 13, and the secondary circuit 20 is provided with a secondary hydraulic pressure sensor 14. The primary hydraulic pressure sensor 13 detects the hydraulic pressure in the primary hydraulic pressure chamber 2d, the secondary hydraulic pressure sensor 14 detects the hydraulic pressure in the secondary hydraulic chamber 2e, and these hydraulic pressure information is sent to the master cylinder pressure control device 8. Sent.

  One end 6a of the input rod 6 on the x-axis positive direction side penetrates the partition wall 2h of the primary piston 2b and is grounded in the primary hydraulic chamber 2d. The gap between the one end 6a of the input rod 6 and the partition wall 2h of the primary piston 2b is sealed to ensure liquid tightness and the one end 6a is slidable in the x-axis direction with respect to the partition wall 2h. . On the other hand, the other end 6b of the input rod 6 on the x-axis negative direction side is connected to the brake pedal BP.

  Accordingly, when the driver steps on the brake pedal BP, the input rod 6 moves to the x-axis positive direction side, and when the driver returns the brake pedal BP, the input rod 6 moves to the x-axis negative direction side.

  The input rod 6 is formed with a large-diameter portion 6f having a larger diameter than the inner periphery of the partition wall 2h of the primary piston 2b and a smaller diameter than the outer diameter of the flange portion 6c. A gap L1 is provided between the x-axis positive direction end face of the large diameter portion 6f and the x-axis negative direction end face of the partition wall 2h when the brake is not operated. When the regenerative cooperative control command is received from the integrated controller 110 by this gap L1, the frictional braking torque is increased by the regenerative braking torque by moving the primary piston 2b relative to the input rod 6 in the negative x-axis direction. It is possible to reduce. When the input rod 6 is displaced relative to the primary piston 2b by the gap L1 in the x-axis positive direction, the surface of the large-diameter portion 6f in the x-axis positive direction comes into contact with the partition wall 2h. The primary piston 2b can move integrally.

  When the input rod 6 or the primary piston 2b moves in the positive x-axis direction, the hydraulic fluid in the primary hydraulic chamber 2d is pressurized, and the pressurized hydraulic fluid is supplied to the primary circuit 10. Further, the secondary piston 2c is moved to the x-axis positive direction side by the pressure of the primary hydraulic chamber 2d by the pressurized hydraulic fluid. When the secondary piston 2c moves to the x axis positive direction side, the hydraulic fluid in the secondary fluid chamber 2e is pressurized, and the pressurized hydraulic fluid is supplied to the secondary circuit 20.

  As described above, the input rod 6 moves in conjunction with the brake pedal BP to pressurize the primary hydraulic chamber 2d. Thus, even if the drive motor (actuator) 50 of the master cylinder pressure control mechanism 5 stops due to a failure, the master cylinder pressure Pmc can be increased by the driver's brake operation, and a predetermined braking torque can be secured. Further, since a force corresponding to the master cylinder pressure Pmc acts on the brake pedal BP via the input rod 6 and is transmitted to the driver as a brake pedal reaction force, the brake pedal reaction force required when the above configuration is not adopted. A device such as a spring for generating the is eliminated. Therefore, the brake booster can be reduced in size and weight, and the mounting property on the vehicle is improved.

  The brake operation amount detection device 7 is for detecting the driver's required deceleration, and is provided on the other end 6 b side of the input rod 6. The brake operation amount detection device 7 is a stroke sensor that detects a displacement amount (stroke) of the input rod 6 in the x-axis direction, that is, a stroke sensor of the brake pedal BP.

  The reservoir tank RES has at least two liquid chambers (not shown) separated from each other by a partition wall (not shown). Each fluid chamber is connected to the primary fluid pressure chamber 2d and the secondary fluid chamber 2e of the master cylinder 2 via the brake circuits 11 and 12, respectively.

  The wheel cylinders (friction braking devices) 4a to 4d have cylinders, pistons, pads, and the like. The pistons are moved by the hydraulic fluid supplied by the cylinders 2a, and the pads connected to the pistons are connected to the disk rotors 40a to 40d. It presses to 40d. The disc rotors 40a to 40d rotate integrally with each wheel, and the brake torque that acts on the disc rotors 40a to 40d becomes a braking force that acts between each wheel and the road surface.

  The master cylinder pressure control mechanism 5 controls the displacement amount of the primary piston 2b, that is, the master cylinder pressure Pmc in accordance with the control command of the master cylinder pressure control device 8, and includes a drive motor 50, a speed reduction device 51, and rotation-translation. Conversion device 55. The master cylinder pressure control device 8 is an arithmetic processing circuit, and controls the operation of the drive motor 50 based on sensor signals from the brake operation amount detection device 7 and the drive motor 50.

[Configuration and operation of master cylinder pressure control mechanism 5]
Next, the configuration and operation of the master cylinder pressure control mechanism 5 will be described.
The drive motor 50 is a three-phase DC brushless motor, and operates with electric power supplied based on a control command from the master cylinder pressure control device 8 to generate a desired rotational torque.

  The reduction gear 51 decelerates the output rotation of the drive motor 50 by a pulley deceleration method. The reduction gear 51 includes a small-diameter drive pulley 52 provided on the output shaft of the drive motor 50, a large-diameter driven pulley 53 provided on the ball screw nut 56 of the rotation-translation conversion device 55, the drive-side pulley 52, and the follower. And a belt 54 wound around the side pulley 53. The reduction gear 51 amplifies the rotational torque of the drive motor 50 by the reduction ratio (radius ratio of the driving pulley 52 and the driven pulley 53) and transmits the amplified torque to the rotation-translation converter 55.

  The rotation-translation converter 55 converts the rotational power of the drive motor 50 into translation power, and presses the primary piston 2b with this translation power. In the first embodiment, a ball screw system is adopted as the power conversion mechanism, and the rotation-translation conversion device 55 includes a ball screw nut 56, a ball screw shaft 57, a movable member 58, and a return spring 59. Yes.

  The first housing member HSG1 is connected to the x-axis negative direction side of the master cylinder 2, and the second housing member HSG2 is connected to the x-axis negative direction side of the first housing member HSG1. The ball screw nut 56 is installed on the inner periphery of the bearing BRG provided in the second housing member HSG2 so as to be rotatable. A driven pulley 53 is fitted to the outer periphery of the ball screw nut 56 on the x-axis negative direction side. A hollow ball screw shaft 57 is coupled to the inner periphery of the ball screw nut 56 by meshing the screws. A plurality of balls are rotatably installed in the gap between the ball screw nut 56 and the ball screw shaft 57.

  A movable member 58 is integrally provided at the end of the ball screw shaft 57 on the x-axis positive direction side, and the primary piston 2b is joined to the surface of the movable member 58 on the x-axis positive direction side. The primary piston 2b is housed in the first housing member HSG1, and the end of the primary piston 2b on the x-axis positive direction side protrudes from the first housing member HSG1 and is fitted to the inner periphery of the master cylinder 2.

  A return spring 59 is provided in the first housing member HSG1 and on the outer periphery of the primary piston 2b. The return spring 59 has an end on the x-axis positive direction side fixed to the surface A on the x-axis positive direction side inside the first housing member HSG1, while an end on the x-axis negative direction side is engaged with the movable member 58. Has been. The return spring 59 is installed to be compressed in the x-axis direction between the surface A and the movable member 58, and urges the movable member 58 and the ball screw shaft 57 to the x-axis negative direction side.

  When the driven pulley 53 rotates, the ball screw nut 56 rotates as a unit, and the ball screw shaft 57 translates in the x-axis direction by the rotational movement of the ball screw nut 56. The primary piston 2b is pressed to the x-axis positive direction side via the movable member 58 by the thrust of the translational motion of the ball screw shaft 57 to the x-axis positive direction side. FIG. 2 shows a state in which the ball screw shaft 57 is at the initial position where the ball screw shaft 57 is displaced to the maximum in the negative x-axis direction when the brake is not operated.

  On the other hand, the elastic force of the return spring 59 acts on the ball screw shaft 57 in the opposite direction (x-axis negative direction side) to the thrust in the x-axis positive direction side. Thus, during braking (in the state where the primary piston 2b is pressed in the positive direction of the x-axis and the master cylinder pressure Pmc is increased), the drive motor 50 stops due to a failure and the return control of the ball screw shaft 57 is impossible. Even in this case, the ball screw shaft 57 returns to the initial position by the reaction force of the return spring 59. As a result, the master cylinder pressure Pmc decreases to near zero, so that it is possible to prevent the occurrence of dragging of the braking force and to avoid the situation where the vehicle behavior becomes unstable due to the dragging.

  A pair of springs (biasing members) 6d and 6e are disposed in the annular space B defined between the input rod 6 and the primary piston 2b. One end of each of the pair of springs 6d and 6e is locked to a flange portion 6c provided on the input rod 6, the other end of the spring 6d is locked to a partition wall 2h of the primary piston 2b, and the other end of the spring 6e is movable. Locked to the member 58. The pair of springs 6d and 6e bias the input rod 6 toward the neutral position of the relative displacement of the primary piston 2b, and the neutral movement of the input rod 6 and the primary piston 2b when the brake is not operated. It has a function to hold in position. By the pair of springs 6d and 6e, when the input rod 6 and the primary piston 2b are relatively displaced in any direction from the neutral position, a biasing force that returns the input rod 6 to the neutral position acts on the primary piston 2b. .

  The drive motor 50 is provided with a rotation angle detection sensor 50a such as a resolver, for example, and a position signal of the motor output shaft detected thereby is input to the master cylinder pressure control device 8. The master cylinder pressure control device 8 calculates the rotation angle of the drive motor 50 based on the input position signal, and based on this rotation angle, the propulsion amount of the rotation-translation conversion device 55, that is, the displacement amount in the x-axis direction of the primary piston 2b. calculate.

  Next, the amplifying action of the thrust of the input rod 6 by the master cylinder pressure control mechanism 5 and the master cylinder pressure control device 8 will be described. In the first embodiment, the master cylinder pressure control device 8 controls the displacement of the primary piston 2b according to the displacement of the input rod 6, that is, the relative displacement of the input rod 6 and the primary piston 2b by the drive motor 50.

  The master cylinder pressure control mechanism 5 and the master cylinder pressure control device 8 displace the primary piston 2b according to the target deceleration determined by the amount of displacement of the input rod 6 due to the driver's brake operation. Thus, the primary hydraulic pressure chamber 2d is pressurized by the thrust of the primary piston 2b in addition to the thrust of the input rod 6, and the master cylinder pressure Pmc is adjusted. That is, the thrust of the input rod 6 is amplified. The amplification ratio (hereinafter referred to as the boost ratio α) is as follows according to the ratio of the axial cross-sectional areas (hereinafter referred to as pressure receiving areas AIR and APP, respectively) of the input rod 6 and the primary piston 2b in the primary hydraulic pressure chamber 2d. It is determined.

The hydraulic pressure of the master cylinder pressure Pmc is adjusted with a pressure equilibrium relationship represented by the following formula (1).
Pmc = (FIR + K × Δx) / AIR = (FPP−K × Δx) / APP (1)
Here, each element in the equation (1) indicating the pressure equilibrium relationship is as follows.
Pmc: Fluid pressure in the primary fluid pressure chamber 2d (master cylinder pressure)
FIR: thrust of input rod 6 FPP: thrust of primary piston 2b AIR: pressure receiving area of input rod 6 APP: pressure receiving area of primary piston 2b K: spring constant of springs 6d and 6e Δx: between input rod 6 and primary piston 2b Relative displacement amount In the first embodiment, the pressure receiving area AIR of the input rod 6 is set smaller than the pressure receiving area APP of the primary piston 2b.

  Here, the relative displacement amount Δx is defined as Δx = Xb−Xi, where Xi is the displacement of the input rod 6 (input rod stroke) and Xb is the displacement (piston stroke) of the primary piston 2b. Therefore, the relative displacement amount Δx is 0 at the neutral position of the relative movement, has a positive sign in the direction in which the primary piston 2b moves forward (strokes toward the positive direction of the x axis) with respect to the input rod 6, and has a negative sign in the opposite direction. . It should be noted that the sliding resistance of the seal is ignored in the equation (1) indicating the pressure equilibrium relationship. The thrust FPP of the primary piston 2b can be estimated from the current value of the drive motor 50.

On the other hand, the boost ratio α can be expressed as the following formula (2).
α = Pmc × (APP + AIR) / FIR (2)
Therefore, when Pmc of the above formula (1) is substituted into the formula (2), the boost ratio α is represented by the following formula (3).
α = (1 + K × Δx / FIR) × (AIR + APP) / AIR (3)
In the boost control, the drive motor 50 (piston stroke Xb) is controlled so that a target master cylinder pressure characteristic is obtained. Here, the master cylinder pressure characteristic refers to a change characteristic of the master cylinder pressure Pmc with respect to the input rod stroke Xi. Corresponding to the stroke characteristic indicating the piston stroke Xb with respect to the input rod stroke Xi and the target master cylinder pressure characteristic, it is possible to obtain a target displacement amount calculation characteristic indicating a change in the relative displacement amount Δx with respect to the input rod stroke Xi. Based on the target displacement amount calculation characteristic data obtained by the verification, a target value of the relative displacement amount Δx (hereinafter, target displacement amount Δx *) is calculated.

  That is, the target displacement amount calculation characteristic indicates a change characteristic of the target displacement amount Δx * with respect to the input rod stroke Xi, and one target displacement amount Δx * is determined corresponding to the input rod stroke Xi. When the rotation of the drive motor 50 (piston stroke Xb) is controlled so as to realize the target displacement amount Δx * determined corresponding to the detected input rod stroke Xi, a master cylinder having a size corresponding to the target displacement amount Δx * A pressure Pmc is generated in the master cylinder 2.

  Here, as described above, the input rod stroke Xi is detected by the brake operation amount detection device 7, the piston stroke Xb is calculated based on the signal of the rotation angle detection sensor 50a, and the relative displacement amount Δx is detected (calculated). It can be determined by the difference in quantity. In the boost control, specifically, the target displacement amount Δx * is set based on the input rod stroke Xi and the target displacement amount calculation characteristic, and the detected (calculated) relative displacement amount Δx is set as the target displacement amount Δx *. The drive motor 50 is controlled (feedback control) so as to match. A stroke sensor that detects the piston stroke Xb may be provided separately.

  In the first embodiment, since the boost control is performed without using the pedal force sensor, the cost can be reduced accordingly. Further, by controlling the drive motor 50 so that the relative displacement amount Δx becomes an arbitrary predetermined value, a boost ratio larger or smaller than the boost ratio determined by the pressure receiving area ratio (AIR + APP) / AIR is obtained. And a braking force based on a desired boost ratio can be obtained.

In the constant boost control, the input rod 6 and the primary piston 2b are integrally displaced, that is, the primary piston 2b is always in the neutral position with respect to the input rod 6, and is displaced with a relative displacement amount Δx = 0. The drive motor 50 is controlled.
Thus, when the primary piston 2b is stroked so that Δx = 0, the boost ratio α is uniquely determined as α = (AIR + APP) / AIR according to the above equation (3). Therefore, by setting AIR and APP based on the required boost ratio and controlling the primary piston 2b so that the piston stroke Xb becomes equal to the input rod stroke Xi, a constant (above required) boost ratio is always obtained. Can be obtained.

  The target master cylinder pressure characteristic in the constant boost control is that the master cylinder pressure Pmc generated as the input rod 6 moves forward (displacement in the positive direction of the x-axis) is a quadratic curve, a cubic curve, or more It becomes large in the form of a multi-order curve (hereinafter collectively referred to as a multi-order curve) in which higher-order curves are combined. The constant boost control has a stroke characteristic in which the primary piston 2b strokes by the same amount as the input rod stroke Xi (Xb = Xi). In the target displacement amount calculation characteristic obtained based on this stroke characteristic and the target master cylinder pressure characteristic, the target displacement amount Δx * is 0 for every input rod stroke Xi.

On the other hand, in the variable boost control, the target displacement amount Δx * is set to a predetermined positive value, and the drive motor 50 is controlled so that the relative displacement amount Δx becomes the predetermined value. Thus, the piston stroke Xb of the primary piston 2b becomes larger than the input rod stroke Xi as the input rod 6 moves forward in the direction of increasing the master cylinder pressure Pmc.
According to the above equation (3), the boost ratio α is (1 + K × Δx / FIR) times as large. That is, it is synonymous with the stroke of the primary piston 2b by an amount obtained by multiplying the input rod stroke Xi by a proportional gain (1 + K × Δx / FIR). In this way, the boost ratio α becomes variable in accordance with the relative displacement amount Δx, and the master cylinder pressure control mechanism 5 works as a boost source to generate a braking torque as required by the driver while greatly reducing the pedal effort. be able to.

From the viewpoint of controllability, the proportional gain (1 + K × Δx / FIR) is desirably 1. However, for example, when a braking torque exceeding the brake operation amount of the driver is required due to an emergency brake or the like, temporarily, The proportional gain can be changed to a value greater than 1.
As a result, even with the same amount of brake operation, the master cylinder pressure Pmc can be increased as compared with the normal time (when the proportional gain is 1), so that a larger braking torque can be generated. Here, the emergency brake can be determined, for example, based on whether or not the time change rate of the signal of the brake operation amount detection device 7 exceeds a predetermined value.

  Thus, in the variable boost control, the forward movement of the primary piston 2b is further advanced with respect to the forward movement of the input rod 6. As a result, the relative displacement amount Δx of the primary piston 2b with respect to the input rod 6 increases as the input rod 6 advances, and the increase in the master cylinder pressure Pmc associated with the advancement of the input rod 6 correspondingly increases from the constant boost control. The drive motor 50 is controlled so as to be larger.

  In the target master cylinder pressure characteristic in the variable boost control, the increase in the master cylinder pressure Pmc that occurs as the input rod 6 moves forward (displacement in the positive x-axis direction) is larger than in the constant boost control (multiple order). Master cylinder pressure characteristics that increase in a curve become steeper). Further, the variable boost control has a stroke characteristic in which an increase in the piston stroke Xb with respect to an increase in the input rod stroke Xi is larger than 1. In the target displacement amount calculation characteristic obtained based on the stroke characteristic and the target master cylinder pressure characteristic, the target displacement amount Δx * increases at a predetermined rate as the input rod stroke Xi increases.

  Further, the variable boost control is the reverse of the above control (the control is such that the piston stroke Xb becomes larger than the input rod stroke Xi as the input rod 6 moves in the direction of increasing the master cylinder pressure Pmc). Also controls. That is, the drive motor 50 is controlled so that the piston stroke Xb becomes smaller than the input rod stroke Xi as the input rod 6 moves in the direction of increasing the master cylinder pressure Pmc. Thereby, at the time of regenerative cooperative control, a friction braking torque can be reduced according to the increase in regenerative braking torque.

[Configuration to execute regenerative cooperative control]
FIG. 3 is a block diagram showing a simplified configuration for executing regenerative cooperative control.
The regeneration cooperative control unit 200 is provided in a part of the integrated controller 110.
The target deceleration calculation unit 210 receives the pedal stroke Sp from the brake operation amount detection device 7, calculates the target deceleration Gs, and further calculates the target braking torque (total braking torque) Ts.

  Then, the subtraction unit 220 subtracts the regenerative execution torque based on the regenerative control executed by the motor controller 102 in accordance with the target braking torque Ts from the target braking torque Ts, and becomes a basic pre-correction nominal friction braking. Torque Tf is calculated.

  In the regenerative cooperative control, when the actual deceleration of the vehicle deviates from the target deceleration Gs corresponding to the driver's required braking torque, the master cylinder pressure command correction unit 230 reduces the master cylinder pressure Pmc in a direction to narrow this deviation. Correct the command value. Further, the master cylinder pressure command correction limiting unit 231 determines whether or not the pedal force fluctuation amount (input rod reaction force Fir) is within a preset allowable value (allowable input rod fluctuation amount Fir_Lmt) by correcting the command value. If the allowable value is exceeded, the command value correction amount is decreased.

  The GP conversion unit 240 adds / subtracts the master cylinder pressure correction amount Pfr finally calculated by the master cylinder pressure command correction unit 230 to / from the nominal master cylinder pressure Pf calculated from the nominal friction braking torque Tf. A master cylinder pressure command value Pfs is calculated. The nominal master cylinder pressure Pf is a basic master cylinder pressure before correction that is set in advance corresponding to the target deceleration Gs.

Hereinafter, the flow of processing for calculating the master cylinder pressure command value Pfs in the regenerative cooperative control executed by the regenerative cooperative control unit 200 shown in FIG. 3 will be described in detail based on the flowcharts of FIGS. 4 to 7. .
FIG. 4 is a flowchart showing an overall process flow for calculating the master cylinder pressure command value Pfs in the regenerative cooperative control.
This regenerative cooperative control is started when the driver performs a braking operation, that is, depressing the brake pedal BP.
In the first step S1, the pedal stroke Sp is read, and the process proceeds to the next step S10.

In step S10, the target deceleration Gs is calculated from the characteristics of the target deceleration Gs with respect to the pedal stroke Sp set in advance as a map, and the process proceeds to the next step S11.
In step S11, the target deceleration Gs is converted into the target braking torque Ts based on the following equation (4), and the process proceeds to the next step S12.
Ts = Gs × α (4)
Α is a coefficient set in advance in the motor controller in order to convert the deceleration into braking torque, and is a value set as a braking force characteristic of the vehicle.

  In step S12, the target braking torque Ts is output to the motor controller 102, and then the process proceeds to the next step S13. In the motor controller 102, the regenerative braking torque Tr with respect to the target braking torque Ts is set in advance as a map. Therefore, in the next step S13, after the regenerative braking torque Tr determined by the motor controller 102 is received and read, the process proceeds to step S14.

In step S14, a nominal friction braking torque Tf, which is a basic friction braking torque before correction, is calculated based on the following formula (5) from the target braking torque Ts and the regenerative braking torque Tr, and the next step S15 is performed. move on.
Tf = Ts−Tr (5)
Here, the nominal friction braking torque Tf, which is the friction braking torque before correction, is set to have the characteristics shown in the PG characteristics shown in FIG.

In step S15, after calculating a nominal master cylinder pressure Pf which is a basic master cylinder pressure before correction, the process proceeds to step S16. The nominal master cylinder pressure Pf is calculated by the following equation (6) based on the nominal friction braking torque Tf that is the friction torque before correction.
Pf = Tf × β (6)
Note that β is a coefficient for converting the friction braking torque into the master cylinder pressure, which is set in advance based on the friction braking force characteristics of the vehicle.

In step S16, the amount of change ΔTr in the regenerative braking torque Tr is calculated from the regenerative braking torque Tr received from the motor controller 102 and the previous value Trz1 stored in the integrated controller 110 based on the following equation (7). The process proceeds to step S17.
ΔTr = Tr−Trz1 (7)
In step S17, it is determined whether or not the change amount ΔTr of the regenerative braking torque Tr is on the decrease side (whether or not the regenerative braking torque Tr is in the direction toward 0). move on. If the change amount ΔTr is not on the decrease side, that is, if the change amount ΔTr is on the increase side or 0, the process proceeds to step S20.

In step S18 which proceeds when the change amount ΔTr of the regenerative braking torque Tr is on the decrease side, the regenerative braking torque Tr0 at the start of the decrease of the regenerative braking torque Tr is stored, and the process proceeds to the next step S19. Note that the storage of the regenerative braking torque Tr0 at the start of reduction in step S18 is executed only when NO is selected in the previous sample and YES is selected in the current sample in step S17.
In step S19, the calculated master cylinder pressure correction amount Pfr is limited to reduce the correction amount as necessary, and then the master cylinder pressure correction amount Pfr is calculated, and the process proceeds to the next step S21. The calculation process of the master cylinder pressure correction amount Pfr in step S19 will be described later with reference to FIG.

  In addition, the limit for reducing the master cylinder pressure correction amount Pfr in step S19 is calculated every time the braking operation is executed, and is discarded every time the braking operation is released after the braking operation is finished. Therefore, each time the braking operation is performed, the processing from step S1 is executed, and the optimum master cylinder pressure correction amount Pfr is calculated each time.

  On the other hand, in step S20 which proceeds when the change amount ΔTr is on the increase side or 0 in step S17, the master cylinder pressure correction amount Pfr is set to the value as it is, and then the process proceeds to step S21. The master cylinder pressure correction amount Pfr is a value calculated to bring the master cylinder pressure command value and the actual master cylinder pressure Pmc close to each other when they deviate from each other. The calculation itself of the master cylinder pressure correction amount Pfr is not a feature of the present application, and may be obtained using various known methods. In this case, for example, the master cylinder pressure correction amount Pfr may be a value that causes the actual master cylinder pressure Pmc to coincide with the master cylinder pressure command value, or may be a value that is calculated so that the two gradually approach each other.

In step S21, the current master cylinder pressure command value Pfs is calculated by the following equation (8) based on the master cylinder pressure correction amount Pfr calculated in step S19 or S20, and then the process proceeds to step S21.
Pfs = Pf + Pfr × (Tr0−Tr) / Tr0 (8)
Note that Tr0 is the regenerative braking torque at the start of reduction stored in step S18 as described above.

  In step S22, the current regenerative braking torque Tr is stored as the previous value Trz1, and one process is completed.

Next, the calculation process of the master cylinder pressure correction amount Pfr in step S19 will be described based on the flowchart of FIG.
In step S23, after calculating the input rod reaction force Fir based on the following equation (9), the process proceeds to step S24.
Fir = Rf × Apms− (PP−IR) × Kspr (9)
Pf is the nominal master cylinder pressure before correction calculated in step S15, APms is the input rod area (plunger area), PP is the primary piston position, IR is the input rod position, and Kspr is the spring constant of the springs 6d and 6e. It is.

In the next step S24, a basic master cylinder pressure Pr0, which is a master cylinder pressure required to generate the same torque as the regenerative braking torque Tr by the friction braking torque, is calculated based on the following formula (10), and then, in step S25. Proceed to
Pr0 = Tr × β (10)
Β is a coefficient used for converting the nominal friction braking torque Tf used in step S15 into the master cylinder pressure Pmc.

In step S25, μ estimated master cylinder pressure correction amount Pr1 based on pad μ (friction coefficient) estimation is calculated, and the process proceeds to step S26. In step S26, the primary piston position PP1 for realizing the master cylinder pressure Pmc obtained by adding the μ estimated master cylinder pressure correction amount Pr1 to the basic master cylinder pressure Pr0 is calculated, and the process proceeds to step S27.
The pad μ estimation varies depending on temperature or the like. For example, at an extremely low temperature, the pad μ is basically higher, and may be about 1.5 times, for example.
The calculation of the μ estimated master cylinder pressure correction amount Pr1 in step S25 and the calculation of the primary piston position PP1 in step S26 will be described later based on the flowchart of FIG.

In step S27, the input rod reaction force after replacement (reaction force when the regenerative braking torque Tr becomes 0) Fir1 is calculated based on the following equation (11), and the process proceeds to step S28. That is, the master cylinder pressure Pmc to be corrected and the reaction force when the primary piston position PP that realizes the master cylinder pressure Pmc is assumed.
Fir1 = (Pr0 + Pr1) × APmc− (PP1−IR) × Kspr (11)
In step S28, the input rod reaction force difference ΔFir before and after replacement is calculated by the following equation (12), and then the process proceeds to step S29.
ΔFir = Fir−Fir1 (12)
In step S29, after calculating an allowable input rod fluctuation amount Fir_Lmt, which is an allowable value of the input rod reaction force difference ΔFir, the process proceeds to step S30. As shown in FIG. 8, the allowable input rod fluctuation amount Fir_Lmt is calculated using a reaction force difference limit value map set in advance so that the allowable input rod fluctuation amount Fir_Lmt increases as the input rod reaction force Fir increases. Ask based.

  In the next step S30, whether or not the input rod reaction force difference ΔFir is within the range of the allowable input rod fluctuation amount Fir_Lmt obtained in step S29, that is, the absolute value of the input rod reaction force difference ΔFir is determined as an allowable input. It is determined whether or not the rod fluctuation amount is Fir_Lmt or less. If the input rod reaction force difference ΔFir is within the allowable input rod fluctuation amount Fir_Lmt, the process proceeds to step S31. If the input rod reaction force difference ΔFir is outside the range, the process proceeds to step S32.

  In step S31, the μ estimated master cylinder pressure correction amount Pr1 calculated in step S25 (corresponding to the μ estimated master cylinder pressure correction amount Pr1 calculated in step S36 described later) is set as the current master cylinder pressure correction amount Pfr. Finish one process.

On the other hand, in step S32 that proceeds when the input rod reaction force difference ΔFir is outside the range of the allowable input rod fluctuation amount Fir_Lmt, as will be described in detail later, the input rod reaction force difference ΔFir is limited (allowable input rod fluctuation amount Fir_Lmt). The master cylinder pressure limit correction amount Pr_Lmt reflecting the above is calculated.
In the next step S33, a final master cylinder pressure limit correction amount Pf_Lmt to which the final limit is applied is calculated from the master cylinder pressure limit correction amount Pr_Lmt, and this processing is finished as a master cylinder pressure correction amount Pfr.

Next, details of the calculation of the μ estimated master cylinder pressure correction amount Pr1 and the calculation of the primary piston position PP1 in steps S25 and S26 will be described with reference to the flowchart of FIG.
First, the vehicle speed Vw is received, and the process proceeds to step S35.
In step S35, the current conversion gain θ is calculated based on a map for obtaining a conversion gain θ for correcting the master cylinder pressure Pmc from the vehicle speed Vw. This conversion gain map is set to conversion gain θ = 1 when the master cylinder pressure Pmc is not corrected.

In step S36, the μ estimated master cylinder pressure correction amount Pr1 based on the friction coefficient estimation of the brake pads (members pressed against the disk rotors 40a to 40d by the pistons of the wheel cylinders 4a to 4d) is calculated by the following equation (13). The friction coefficient μ is estimated from the conversion gain θ calculated in step S35.
Pr1 = (θ−1) × Pr0 (13)
In the following step S37, the primary piston position PP1 that realizes the corrected master cylinder pressure obtained by adding the μ estimated master cylinder pressure correction amount Pr1 to the basic master cylinder pressure Pr0 is calculated from a preset hydraulic fluid pressure characteristic map. . In this fluid quantity / hydraulic pressure characteristic map, the horizontal axis represents the primary piston position, and the vertical axis represents the master cylinder pressure.

Next, calculation of the master cylinder pressure limit correction amount Pr_Lmt reflecting the limit of the input rod reaction force difference ΔFir (allowable input rod fluctuation amount Fir_Lmt) in step S32 will be described based on the flowchart of FIG.
First, in step S39, the μ estimated master cylinder pressure correction amount Pr1 calculated in step S36 is temporarily stored as a master cylinder pressure limit correction amount Pr_Lmt, and then the process proceeds to step S40.

In step S40, after calculating the fluctuation limit correction amount Pr_Lmt0 obtained by subtracting a minute amount γ from the master cylinder pressure limit correction amount Pr_Lmt, the process proceeds to step S41. If the μ estimated master cylinder pressure correction amount Pr1 is a negative value, a minute amount γ is added.
In step S41, the assumed primary piston position PP_Lmt assumed when the variation restriction correction amount Pr_Lmt0 calculated in step S40 is adopted as the correction amount is calculated, and then the process proceeds to step S42. Note that the calculation of the assumed primary piston position PP_Lmt in step S41 is performed using the same hydraulic fluid pressure characteristics as in step S37.

In step S42, an input rod reaction force fluctuation amount ΔFir_Lmt0 before and after correction is calculated before and after correction when correcting to the assumed primary piston position PP_Lmt. First, the variation restriction correction amount Pr_Lmt0 calculated in step S40 and the corrected input rod reaction force Fir_Lmt0 at the assumed primary piston position PP_Lmt calculated in step S41 are calculated by the following equation (14).
Fir_Lmt0 =
(Pr0 + Pr_Lmt) × APmc− (PP_Lmt−IR) × Kspr (14)
Then, the corrected input rod reaction force Fir_Lmt0 before and after correction, which is the difference between the corrected input rod reaction force Fir_Lmt0 calculated by the equation (14) and the current input rod reaction force Fir calculated in step S23, is expressed by the following equation. Calculate according to (15).
ΔFir_Lmt0 = Fir−Fir_Lmt0 (15)
In step S43, it is determined whether or not the absolute value | ΔFir_Lmt0 | of the before / after correction input rod reaction force fluctuation amount ΔFir_Lmt0 calculated in steps S40 to S42 is less than the allowable input rod fluctuation amount Fir_Lmt calculated in step S29.
If | ΔFir_Lmt0 | <Fir_Lmt, the process proceeds to step S44; otherwise, the process proceeds to step S45.

In step S44, the variation limit correction amount Pr_Lmot0 reflecting the limit of the input rod reaction force difference is set as the final master cylinder pressure limit correction amount Pf_Lmt, and one process is completed.
On the other hand, in step S45, the fluctuation limit correction amount Pr_Lmt0 is set as the master cylinder pressure limit correction amount Pr_Lmt, and the process returns to step S40. Therefore, it is determined again whether or not the corrected input rod reaction force fluctuation amount ΔFir_Lmt0 before and after correction is less than the allowable input rod fluctuation amount Fir_Lmt based on the fluctuation restriction correction amount Pr_Lmt0 that is fluctuated by a small amount γ from the master cylinder pressure limit correction amount Pr_Lmt. To do. Then, the process of changing the master cylinder pressure limit correction amount Pr_Lmt by a small amount γ is repeated until the before-and-after-correction input rod reaction force fluctuation amount ΔFir_Lmt0 becomes less than the allowable input rod fluctuation amount Fir_Lmt.

(Operation of Embodiment 1)
Next, the operation of the vehicular braking control apparatus according to the first embodiment will be described. First, a comparative example in which a problem occurs when the actual characteristics and the control characteristics of the master cylinder pressure and the friction braking torque deviate from each other. The operation of will be described.

(Comparative example)
9 and 10 show that when the wheel speed (vehicle speed Vw) decreases to the set vehicle speed Vw0, the target friction braking torque differs from the actual friction braking torque when the regenerative braking torque is switched to the friction braking torque. Shows the case. That is, the case where the actual PG characteristics are different from the control PG characteristics due to the influence of the vehicle speed and temperature is shown.
In the switching control of the comparative example shown in FIG. 9, the master cylinder pressure (nominal master cylinder pressure Pf) is controlled so as to generate the friction braking torque (nominal friction braking torque Tf) by the amount of decrease in the regenerative braking torque Tr. Yes. However, the friction braking torque actually generated with respect to the control of the master cylinder pressure deviates as shown by a one-dot chain line or two-dot chain line in the figure, and the deceleration G is a high decrease with respect to the control target deceleration G00. The speed G01 or a low deceleration G02 is obtained.

  In such a case, for example, if the first embodiment is applied, the master cylinder pressure command correction unit 230 performs feedback correction, and the master cylinder pressure that brings the decelerations G01 and G02 close to the control target deceleration G00. A correction amount Pfr is calculated.

FIG. 10 shows a case where the actual friction braking torque fluctuates higher than the target friction braking torque.
That is, FIG. 10 shows a case where the actual PG characteristic indicated by the dotted line fluctuates so that the deceleration becomes higher than the control PG characteristic (deceleration with respect to the pedal stroke) indicated by the solid line in the figure. An example of the operation is shown.
In this case, the feedback cylinder correction is performed to reduce the master cylinder pressure Pmc as shown by the dotted line with respect to the target value shown by the solid line in the drawing.

When the driver depresses the brake pedal BP in this way, when the master cylinder pressure Pmc is reduced, the input rod reaction force (Fir) fluctuates and the pedal force decreases as shown in the figure (indicated by the dotted line in the figure). Variation with the pedal force shown) occurs.
In this case, the reaction force (stepping force) against the brake pedal BP may fluctuate, which may cause the driver to feel uncomfortable.

(Operation of Embodiment 1)
The vehicular braking control apparatus according to the first embodiment suppresses reaction force (stepping force) fluctuations with respect to the brake pedal BP in the above-described comparative example, and suppresses the uncomfortable feeling of pedaling force fluctuations applied to the driver. Will be described with reference to FIG.
FIG. 11 shows the operation of the first embodiment when the actual PG characteristic is deviated from the control PG characteristic as in the comparative example.

From time t1 when the driver performs a braking operation and the wheel speed (vehicle speed Vw) decreases and decreases to the set vehicle speed Vw0, the regenerative cooperative control unit 200 starts replacement control, and the regenerative braking torque Tr is set. Decrease with a gradient. This gradient is set according to the vehicle speed, the target deceleration Gs, and the like.
When a decrease in the regenerative braking torque Tr is detected (C1), first, the regenerative braking torque Tr0 at that time is stored (C2). This storage is based on the processing of steps S17 → S18.

Next, the input rod reaction force Fir at that time is calculated (C3), and the basic master cylinder pressure Pr0 when the regenerative braking torque Tr is set to 0 is calculated (C4). These calculations are based on the processing from step S23 to S24.
Then, by the processing in steps S23 to S26 of FIG. 5, the μ estimated master cylinder pressure correction amount Pr1 based on the pad μ estimation is obtained, and this correction is realized from the master cylinder pressure at the time of regenerative braking torque Tr = 0. The primary piston position PP1 is calculated (C5).
Further, the input rod reaction force Fir1 after replacement is calculated based on the primary piston position PP1 (S27), and the input rod reaction force difference ΔFir (= Fir−Fir1) before and after this replacement is calculated (C6).

Next, based on the input rod reaction force Fir stored at time t1, an input rod reaction force difference limit value ± Fir_Lmt, which is a limit value in which the fluctuation is allowed, is calculated (C7). When the input rod reaction force difference ΔFir is not within the range of the input rod reaction force difference limit value ± Fir_Lmt, the master cylinder pressure correction is performed to limit the input rod reaction force difference ΔFir to be within this range. The amount Pfr is calculated (C8).
That is, in the μ estimated master cylinder pressure correction amount Pr1 when the input rod reaction force Fir is not taken into consideration, the master cylinder pressure Pmc at the time t2 becomes a value corresponding to Pr0 + Pr1. On the other hand, the master cylinder pressure Pmc given the master cylinder pressure limit correction amount Pr_Lmt limited based on the allowable input rod fluctuation amount Fir_Lmt of the input rod 6 calculated in the process of (C7) is as shown in (C9). , The fluctuation amount is suppressed.

  Then, at time t2 when the regenerative braking torque Tr is 0, the master cylinder pressure command value that is output as time elapses based on the processing of step S21 so that the master cylinder pressure Pmc of (C9) is obtained. Pfs is calculated (C10).

  In the first embodiment, when the master cylinder pressure limit correction amount Pr_Lmt is obtained by the process of (C9) above, a predetermined amount from the master cylinder pressure limit correction amount Pr_Lmt corresponding to the μ estimated master cylinder pressure correction amount Pr1 is determined. A variation restriction correction amount Pr_Lmt0 obtained by subtracting a minute amount γ is obtained. Further, it is determined whether or not the input rod reaction force fluctuation amount ΔFir_Lmt0 before and after correction when the fluctuation limit correction amount Pr_Lmt0 is applied to the basic master cylinder pressure Pr0 is within the range of the allowable input rod fluctuation amount ± Fir_Lmt (S43). Then, the value obtained by subtracting a slight amount γ from the fluctuation limit correction amount Pr_Lmt0 is set as the fluctuation limit correction amount Pr_Lmt0 until the input rod reaction force fluctuation amount ΔFir_Lmt0 before and after correction falls within the range of the allowable input rod fluctuation amount ± Fir_Lmt. repeat. Therefore, it is possible to obtain a marginal variation restriction correction amount Pr_Lmt0 that falls within the range of the allowable input rod fluctuation amount ± Fir_Lmt, and to ensure that the input rod reaction force fluctuation amount ΔFir_Lmt0 before and after correction is within the allowable input rod fluctuation amount ± Fir_Lmt range. Can fit inside.

As described above, even when the PG characteristic, which is the characteristic of the friction braking torque with respect to the master cylinder pressure Pmc, varies during the braking torque replacement control, the input rod reaction force Fir at the start of the reduction of the regenerative braking torque Tr is obtained. The fluctuation amount of is suppressed within the set range.
For this reason, when the master cylinder pressure correction according to the change of the PG characteristic is performed during the switching control, it is possible to prevent the driver from feeling uncomfortable with the change in the pedal depression force.

Next, the effect of Embodiment 1 is demonstrated.
In the vehicle brake control device of the first embodiment, the following effects can be obtained.
1) The vehicle braking control apparatus of Embodiment 1
An input rod 6 as an input member that moves forward and backward by the operation of the brake pedal BP, a primary piston 2b as an assist member provided so as to be relatively movable with respect to the moving direction of the input rod 6, and the primary piston 2b Springs 6d and 6e as urging members for urging the input rod 6 toward the neutral position of both relative displacements, and a primary piston 2b as the assist member according to the amount of movement of the input rod 6 as the input member A master motor pressure control mechanism 5 as a brake booster that generates a master cylinder pressure Pmc boosted in the master cylinder 2 by the thrust of the primary piston 2b. When,
Wheel cylinders 4a to 4d as friction braking devices for applying friction braking torque to the wheels according to the master cylinder pressure Pmc;
A motor generator MG as a regenerative braking device for applying a regenerative braking torque to the wheel;
As a regenerative cooperative control device that executes regenerative cooperative control for controlling the friction braking torque and the regenerative braking torque so that a total braking torque including the friction braking torque and the regenerative braking torque becomes a required braking torque of the driver. Regenerative cooperative control unit 200;
With
The regenerative cooperative control unit 200 includes:
In the regenerative cooperative control, when the actual deceleration of the vehicle deviates from the target deceleration corresponding to the driver's required braking torque, when the command value of the master cylinder pressure Pmc is corrected in a direction to narrow the deviation. Then, it is determined whether or not the pedaling force fluctuation amount is within a preset allowable value (allowable input rod fluctuation amount Fir_Lmt) by correcting the command value, and if the allowable value is exceeded, the correction value of the command value is set. A master cylinder pressure command correction limiting unit 231 for reducing the pressure is provided.
Therefore, when the master cylinder pressure command correction limiting unit 231 corrects the master cylinder pressure Pmc in accordance with the actual deceleration deviating from the target deceleration during the regenerative cooperative control, the pedaling force fluctuation amount has an allowable value. If the correction amount exceeds the correction amount, the correction amount is decreased.
Due to the decrease in the correction amount, the amount of change in the master cylinder pressure Pmc due to the correction is also reduced, and the pedaling force fluctuation can be suppressed.

2) The vehicle braking control device of the first embodiment is
When the master cylinder pressure command correction limiting unit 231 decreases the correction amount, the master cylinder pressure command correction limiting unit 231 decreases the correction amount (master cylinder pressure limit correction amount Pr_Lmt) by a small amount γ as a preset decrease amount. The pedaling force fluctuation amount (before / after correction input rod reaction force fluctuation amount ΔFir_Lmt0) according to the corrected amount after reduction is obtained, and the set reduction amount is increased until the pedaling force fluctuation amount falls within the allowable value (allowable input rod fluctuation amount Fir_Lmt). It is characterized by repeating the decrease.
Therefore, the last master cylinder pressure limit correction amount Pf_Lmt that is within the range of the allowable input rod fluctuation amount ± Fir_Lmt can be obtained. The input rod reaction force fluctuation amount ΔFir_Lmt0 before and after correction can be reliably kept within the range of the allowable input rod fluctuation amount ± Fir_Lmt, and the pedal force fluctuation can be suppressed.

3) The vehicle braking control device of the first embodiment is
The master cylinder pressure command correction limiting unit 231 discards the command value that forms the final master cylinder pressure limit correction amount Pf_Lmt, which is decreased by the release of the operation of the brake pedal BP, and the master cylinder pressure It returns to nominal master cylinder pressure Pf preset as Pmc.
Therefore, the fluctuation of the actual PG characteristic occurs every time the braking operation is performed due to a change in the pad μ caused by the vehicle speed, temperature, or the like. For this reason, by obtaining the final master cylinder pressure limit correction amount Pf_Lmt in accordance with the situation at that time for each braking operation and forming the command value, the effect 1) can be obtained more reliably.

  As mentioned above, although the vehicle brake control apparatus of the present invention has been described based on the embodiment, the specific configuration is not limited to this embodiment, and the invention according to each claim of the claims. Design changes and additions are permitted without departing from the gist of the present invention.

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

1 Brake Device 2 Master Cylinder 2b Primary Piston (Assist Member)
4a to 4d Foil cylinder (friction braking device)
5 Master cylinder pressure control mechanism (brake booster)
6 Input rod (input member)
6d Spring (biasing member)
6e Spring (biasing member)
50 Drive motor (actuator)
102 Motor controller (regenerative cooperative control device)
109 Brake controller (regenerative cooperative control device)
110 Integrated controller (regenerative cooperative control device)
200 Regenerative cooperative control unit (Regenerative cooperative control device)
230 Master cylinder pressure command correction unit 231 Master cylinder pressure command correction limiting unit BP Brake pedal Fir_Lmt Allowable input rod fluctuation amount (allowable value)
Gs Target deceleration MG Motor generator (regenerative braking device)
Pf Nominal master cylinder pressure (basic master cylinder pressure)
Pf_Lmt Final master cylinder pressure limit correction amount Tf Nominal friction braking torque Tr Regenerative braking torque Ts Target braking torque (total braking torque)
γ Slight amount (setting reduction amount)

Claims (3)

An input member that moves forward and backward by the operation of the brake pedal, an assist member that is movable relative to the direction of movement of the input member, and the input member is directed toward the neutral position of the relative displacement of the assist member. An urging member that urges the input member and an actuator that moves the assist member forward and backward according to the amount of movement of the input member, and generates a master cylinder pressure boosted in the master cylinder by the thrust of the assist member. A brake booster,
A friction braking device for applying a friction braking torque to the wheel according to the master cylinder pressure;
A regenerative braking device for applying a regenerative braking torque to the wheel;
A regenerative cooperative control device that performs regenerative cooperative control for controlling the friction braking torque and the regenerative braking torque so that a total braking torque including the friction braking torque and the regenerative braking torque becomes a required braking torque of a driver;
With
The regenerative cooperative control device is:
In the regenerative cooperative control, when the actual deceleration of the vehicle deviates from a target deceleration corresponding to the driver's required braking torque, when correcting the master cylinder pressure command value in a direction to narrow the deviation, A master cylinder pressure command correction limiting unit that determines whether or not the pedal force fluctuation amount falls within a preset allowable value by correcting the command value, and decreases the correction value of the command value when the allowable value is exceeded. A vehicle braking control device comprising: The vehicle brake control device according to claim 1,
When the master cylinder pressure command correction limiting unit decreases the correction amount, the master cylinder pressure command correction limiting unit decreases the correction amount by a preset reduction amount, obtains the pedal force fluctuation amount by the correction amount after the decrease, The vehicular braking control apparatus, wherein the set reduction amount is repeatedly reduced until a pedal force fluctuation amount falls within the allowable value. In the vehicle brake control device according to claim 1 or 2,
The master cylinder pressure command correction limiting unit discards the command value that has decreased the correction amount in response to the release of the operation of the brake pedal, and is set in advance as the master cylinder pressure based on the target deceleration A vehicular braking control device that returns the pressure to a master cylinder pressure.