JP2016193645A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make both compatible in restraint of a variation in vehicle deceleration to operation of a brake pedal and restraint of generation of fluid pressure by calculation processing of fluid pressure characteristic data.SOLUTION: Rigidity (that is, downstream rigidity) of a brake liquid pressure circuit changes by a variation in calipers of wheel cylinders 3L, 3R, 4L and 4R, as well as the temperature, an abrasion condition and the deterioration of a friction pad. A first ECU 26 comprises fluid pressure characteristic calculation means for calculating fluid pressure characteristic data for an operation quantity of a brake pedal 5 for realizing a brake characteristic corresponding to the downstream rigidity by the operation quantity, a motor position of an electric motor 21 and brake liquid pressure by a hydraulic pressure sensor 29. In brake pedal operation time on and after calculating the fluid pressure characteristic data by this fluid pressure characteristic calculation means, control of the electric motor 21 is executed in response to a target fluid pressure value calculated on the basis of the fluid pressure characteristic data used in brake pedal operation time of the last time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a brake control device suitably used for a vehicle such as a four-wheel automobile.

  A brake control device mounted on a vehicle such as a four-wheeled vehicle has a configuration that variably controls a brake fluid pressure generated by a master cylinder by driving an electric motor in accordance with a driver's brake pedal operation. is there. This type of brake control device calculates the operation amount of the brake pedal, and controls the electric motor so that the relative displacement between the input member connected to the brake pedal and the primary piston of the master cylinder becomes a preset target relative displacement. Either piston position control for controlling rotation or hydraulic pressure control for controlling rotation of the electric motor so that the hydraulic pressure in the master cylinder becomes a preset target hydraulic pressure with respect to the operation amount of the brake pedal. Control is performed by switching between the two (for example, see Patent Document 1).

  Here, when switching from the piston position control to the hydraulic pressure control, the switching timing is set so that the hydraulic pressure command value by the piston position control and the hydraulic pressure command value by the hydraulic pressure control are continuously connected. When the pressure command value is not continuously connected, the reference hydraulic pressure characteristic used in the hydraulic pressure control is corrected. Also, regenerative braking that brakes the vehicle is performed by recovering kinetic energy as electric power by driving and controlling the generator using the inertial force generated by the rotation of each wheel during vehicle deceleration and braking. There is. In the brake control device, the regenerative braking force and the friction braking force for braking the vehicle by applying the hydraulic pressure of the master cylinder to the wheel cylinder are coordinated to adjust the braking force according to the operation of the brake pedal. Some perform regenerative cooperative control.

Japanese Unexamined Patent Publication No. 2014-111394

  By the way, in the brake control device of the prior art, the amount of brake fluid required for the fluid pressure in the brake fluid pressure circuit (hereinafter referred to as the fluid pressure in the brake fluid pressure circuit) due to variations in calipers constituting part of the wheel cylinder, friction pad temperature, wear condition, deterioration, etc. Sometimes referred to as downstream stiffness). This change in downstream stiffness may cause fluctuations in vehicle deceleration with respect to brake pedal operation when switching from position control to hydraulic pressure control. Therefore, calculation of hydraulic pressure characteristic data according to downstream stiffness Is performed every time the brake pedal is operated. However, in order to calculate the hydraulic pressure characteristic data according to the downstream rigidity, it is necessary to generate the hydraulic pressure from the master cylinder, and for example, the amount of the braking force generated by the hydraulic pressure is applied to the regenerative braking force. There is a problem that the energy recovery rate due to the regenerative cooperative control decreases.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to suppress the fluctuation of the vehicle deceleration with respect to the operation of the brake pedal and the suppression of the generation of hydraulic pressure by the calculation processing of hydraulic pressure characteristic data. It is an object of the present invention to provide a brake control device that can achieve both.

  In order to solve the above-described problems, a brake control device according to the present invention includes an operation amount detection unit that detects an operation amount of a brake pedal and an electric motor that generates a brake hydraulic pressure by moving a piston of a master cylinder connected to a wheel cylinder. A motor, motor position detecting means for detecting a motor position of the electric motor, hydraulic pressure detecting means for detecting the brake hydraulic pressure generated by driving the electric motor, and the electric motor according to an operation amount of the brake pedal. Control means for controlling a motor, wherein the control means is a hydraulic pressure with respect to the operation amount for realizing a brake characteristic according to a state of the wheel cylinder by the operation amount, the motor position and the brake hydraulic pressure. A hydraulic pressure characteristic calculating unit that calculates characteristic data, and the hydraulic pressure characteristic data is calculated by the hydraulic pressure characteristic calculating unit; During the subsequent operation of the brake pedal, and characterized in that for controlling the electric motor in accordance with the target fluid pressure value which is calculated on the basis of the liquid pressure characteristics data used in the previous operation of the brake pedal.

  ADVANTAGE OF THE INVENTION According to this invention, suppression of the fluctuation | variation of the vehicle deceleration with respect to operation of a brake pedal and suppression of generation | occurrence | production of hydraulic pressure by calculation processing of hydraulic pressure characteristic data can be made compatible.

1 is an overall configuration diagram showing a brake system having a brake control device according to an embodiment of the present invention. It is sectional drawing which expands and shows the electric booster etc. in FIG. FIG. 3 is a control block diagram of an ECU that performs drive control of the electric booster shown in FIG. 2. It is a characteristic diagram which shows the characteristic of the reference position which set the relationship between the operation amount of a brake pedal, and the target position of a booster piston. It is a characteristic line figure showing the characteristic of standard fluid pressure which set up the relation between the amount of operation of a brake pedal, and target fluid pressure. It is a characteristic diagram which shows the characteristic of the target hydraulic pressure offset with respect to the reference | standard hydraulic pressure characteristic by the relationship with pedal operation amount. It is a characteristic diagram which shows the operation amount-hydraulic pressure characteristic in the case of performing control switching processing between piston position control and hydraulic pressure control based on the switching reference hydraulic pressure. It is a characteristic diagram which shows the operation amount-hydraulic pressure characteristic in the case of performing a hydraulic pressure control process immediately after the start of pedal operation. It is a flowchart which shows the process for determining the target hydraulic-pressure characteristic data by embodiment. FIG. 10 is a flowchart specifically illustrating a large difference process in FIG. 9. FIG. FIG. 10 is a flowchart specifically showing processing for determining whether or not the downstream stiffness in FIG. 9 has changed. FIG.

  Hereinafter, a case where a brake control device according to an embodiment of the present invention is mounted on a four-wheeled vehicle will be described in detail with reference to FIGS. 1 to 11 of the accompanying drawings.

  Here, FIG. 1 conceptually shows a brake system having the brake control device according to the present embodiment. In FIG. 1, left and right front wheels 1L and 1R and left and right rear wheels 2L and 2R are provided below a vehicle body (not shown) constituting a vehicle body. The left and right front wheels 1L and 1R are respectively provided with front wheel side wheel cylinders 3L and 3R, and the left and right rear wheels 2L and 2R are respectively provided with rear wheel side wheel cylinders 4L and 4R. These wheel cylinders 3L, 3R, 4L, 4R constitute a hydraulic disc brake or drum brake cylinder, and apply braking force to each wheel (front wheels 1L, 1R and rear wheels 2L, 2R). It is.

  The brake pedal 5 is provided on the front board (not shown) side of the vehicle body. The brake pedal 5 is depressed in the direction of arrow A in FIG. 1 by the driver when the vehicle pedal is operated. The brake pedal 5 is provided with a brake switch 6 and an operation amount detector 7. The brake switch 6 detects the presence or absence of the brake pedal operation of the vehicle and turns on and off a brake lamp (not shown), for example. It is. The operation amount detector 7 constitutes operation amount detection means for detecting the depression operation amount (stroke amount) or the depression force of the brake pedal 5, and outputs the detection signal to ECUs 26, 32, the vehicle data bus 28, etc., which will be described later. To do. When the brake pedal 5 is depressed, brake fluid pressure is generated in the master cylinder 8 via an electric booster 16 described later.

  As shown in FIG. 2, the master cylinder 8 has a bottomed cylindrical cylinder body 9 that is closed with one side being an open end and the other side being a bottom. The cylinder body 9 is provided with first and second supply ports 9A and 9B communicating with a reservoir 14 described later. The first supply port 9A communicates with and is blocked from the first hydraulic chamber 11A by a sliding displacement of a booster piston 18 described later. On the other hand, the second supply port 9B is communicated with or blocked from the second hydraulic chamber 11B by a second piston 10 described later.

  The cylinder main body 9 is detachably fixed to a booster housing 17 of an electric booster 16 to be described later using a plurality of mounting bolts (not shown) or the like. The master cylinder 8 includes a cylinder body 9, a first piston (a booster piston 18 and an input rod 19 described later) and a second piston 10, a first hydraulic pressure chamber 11A, and a second hydraulic pressure chamber 11B. The first return spring 12 and the second return spring 13 are included.

  In this case, in the master cylinder 8, a first piston as a primary piston (that is, a P piston) is constituted by a booster piston 18 and an input rod 19 which will be described later. The first hydraulic chamber 11A formed in the cylinder body 9 is defined between the second piston 10 as a secondary piston and the booster piston 18 (and the input rod 19). The second hydraulic chamber 11 </ b> B is defined in the cylinder body 9 between the bottom of the cylinder body 9 and the second piston 10.

  The first return spring 12 is located between the booster piston 18 and the second piston 10 in the first hydraulic chamber 11 </ b> A, and the booster piston 18 faces the opening end side of the cylinder body 9. Is energized. The second return spring 13 is located in the second hydraulic pressure chamber 11B and is disposed between the bottom portion of the cylinder body 9 and the second piston 10, and the second piston 10 is connected to the first hydraulic pressure. It is energized toward the chamber 11A side.

  In the cylinder body 9 of the master cylinder 8, the booster piston 18 (input rod 19) and the second piston 10 are displaced toward the bottom of the cylinder body 9 in response to the depression operation of the brake pedal 5. When the first and second supply ports 9A and 9B are blocked by the booster piston 18 and the second piston 10, the brake fluid in the first and second hydraulic chambers 11A and 11B causes the master cylinder 8 to Brake fluid pressure is generated. On the other hand, when the operation of the brake pedal 5 is released, the booster piston 18 (and the input rod 19) and the second piston 10 are brought into the opening of the cylinder body 9 by the first and second return springs 12 and 13. It is displaced in the direction indicated by arrow B. At this time, the master cylinder 8 releases the hydraulic pressure in the first and second hydraulic pressure chambers 11A and 11B while receiving replenishment of brake fluid from the reservoir.

  The cylinder body 9 of the master cylinder 8 is provided with a reservoir 14 as a hydraulic fluid tank in which brake fluid is accommodated. The reservoir 14 supplies and discharges brake fluid to and from the hydraulic chambers 11A and 11B in the cylinder body 9. That is, while the first supply port 9A is communicated with the first hydraulic chamber 11A by the booster piston 18, and the second supply port 9B is communicated with the second hydraulic chamber 11B by the second piston 10. The brake fluid in the reservoir 14 is supplied to and discharged from the hydraulic chambers 11A and 11B.

  On the other hand, when the first supply port 9A is blocked from the first hydraulic chamber 11A by the booster piston 18 and the second supply port 9B is blocked from the second hydraulic chamber 11B by the second piston 10, Supply and discharge of the brake fluid in the reservoir 14 with respect to these hydraulic chambers 11A and 11B is cut off. For this reason, brake fluid pressure is generated in the first and second fluid pressure chambers 11A and 11B of the master cylinder 8 in accordance with the brake operation, and this brake fluid pressure is, for example, a pair of cylinder side fluid pressure pipes 15A. , 15B to the hydraulic pressure supply device 30 (that is, ESC 30) described later.

  Between the brake pedal 5 and the master cylinder 8 of the vehicle, an electric booster 16 as a booster that increases the operating force of the brake pedal 5 is provided. The electric booster 16 variably controls the brake hydraulic pressure generated in the master cylinder 8 by driving and controlling an electric actuator 20 described later based on the output of the operation amount detector 7. The electric booster 16 is provided with a booster housing 17 fixed to a vehicle front wall (not shown), which is a front board of the vehicle body, and a movably provided booster housing 17 with respect to an input rod 19 described later. And a booster piston 18 as a relatively movable piston, and an electric actuator 20 (to be described later) for moving the booster piston 18 forward and backward in the axial direction of the master cylinder 8 and applying a booster thrust to the booster piston 18. Yes.

  The booster piston 18 is configured by a cylindrical member that is slidably inserted in the cylinder body 9 of the master cylinder 8 from the opening end side in the axial direction. On the inner peripheral side of the booster piston 18, an input rod 19 as an input member that is directly pushed in accordance with the operation of the brake pedal 5 and moves forward and backward in the axial direction of the master cylinder 8 (that is, the directions indicated by arrows A and B). Is slidably inserted. The input rod 19 together with the booster piston 18 constitutes the first piston (ie, P piston) of the master cylinder 8, and the brake pedal 5 is connected to the rear side (one axial side) end of the input rod 19. Has been. In the cylinder body 9, a first hydraulic chamber 11A is defined between the second piston 10 and the booster piston 18 (input rod 19).

  The booster housing 17 is provided between a cylindrical speed reducer case 17A that accommodates a speed reduction mechanism 23 and the like to be described later, and the speed reducer case 17A and the cylinder body 9 of the master cylinder 8, and the booster piston 18 is disposed in the axial direction. The cylindrical support case 17B supported so as to be slidably displaceable and the support case 17B across the reduction gear case 17A are disposed on the opposite side (one axial direction) to the axial direction of the reduction gear case 17A. And a stepped cylindrical lid 17C that closes the opening on the side. A support plate 17D for fixedly supporting an electric motor 21, which will be described later, is provided on the outer peripheral side of the speed reducer case 17A.

  As shown in FIG. 2, the input rod 19 is inserted into the booster housing 17 from the lid body 17C side, and extends in the booster piston 18 in the axial direction toward the first hydraulic pressure chamber 11A. Between the booster piston 18 and the input rod 19, a pair of neutral springs 19A, 19B are interposed. The booster piston 18 and the input rod 19 are elastically held in a neutral position by the spring force of the neutral springs 19A and 19B, and the spring force of the neutral springs 19A and 19B acts on the relative displacement in the axial direction. It has become.

  The front end side (the other side in the axial direction) of the input rod 19 receives the hydraulic pressure generated in the first hydraulic pressure chamber 11 </ b> A during braking as a brake reaction force, and the input rod 19 transmits this to the brake pedal 5. To do. Thereby, an appropriate treading response is given to the driver of the vehicle via the brake pedal 5, and a good pedal feeling (effectiveness of the brake) can be obtained. As a result, the operational feeling of the brake pedal 5 can be improved, and the pedal feeling (stepping response) can be kept good.

  Further, the input rod 19 has a structure capable of abutting on the booster piston 18 and advancing the booster piston 18 when the input rod 19 is advanced by a predetermined amount with respect to the booster piston 18. With this structure, when an electric actuator 20 or a first ECU 26, which will be described later, fails, the booster piston 18 can be advanced by the depression force on the brake pedal 5 to generate hydraulic pressure in the master cylinder 8. Yes.

  The electric actuator 20 of the electric booster 16 includes an electric motor 21 provided on a reduction gear case 17A of the booster housing 17 via a support plate 17D, and the rotation of the electric motor 21 is reduced to reduce the rotation inside the reduction gear case 17A. A speed reduction mechanism 23 such as a belt for transmitting to the cylindrical rotating body 22 and a linear motion mechanism 24 such as a ball screw for converting the rotation of the cylindrical rotating body 22 into the axial displacement (advance and retreat movement) of the booster piston 18 are configured. . The booster piston 18 and the input rod 19 have their front ends (ends on the other side in the axial direction) facing the first hydraulic chamber 11A of the master cylinder 8, and the pedaling force (thrust force) transmitted from the brake pedal 5 to the input rod 19 ) And the booster thrust transmitted from the electric actuator 20 to the booster piston 18, the brake fluid pressure is generated in the master cylinder 8.

  That is, the booster piston 18 of the electric booster 16 is driven by the electric actuator 20 based on the output (that is, the braking command) of the operation amount detector 7, and brake fluid pressure (master cylinder pressure) is applied to the master cylinder 8. The pump mechanism to generate is comprised. In addition, a return spring 25 that constantly urges the booster piston 18 in the braking release direction (the direction indicated by the arrow B in FIG. 1) is provided in the support case 17B of the booster housing 17. The booster piston 18 is returned in the arrow B direction to the initial position shown in FIGS. 1 and 2 by the driving force when the electric motor 21 is rotated in the reverse direction and the urging force of the return spring 25 when the brake operation is released. Is.

  The electric motor 21 is configured using, for example, a DC brushless motor, and the electric motor 21 is provided with a rotation sensor 21A called a resolver and a current sensor 21B that detects a motor current. The rotation sensor 21A detects the rotation position (that is, the motor position) of the electric motor 21, and outputs the detection signal to a control unit (hereinafter referred to as a first ECU 26) that is a first control circuit. The first ECU 26 performs feedback control of the electric motor 21 (that is, the booster piston 18) according to the rotational position signal. Further, the rotation sensor 21A constitutes a motor position detection means, and has a function as a piston position detection means for detecting the absolute displacement of the booster piston 18 with respect to the vehicle body based on the detected rotation position (motor position) of the electric motor 21. ing.

  Here, the rotation sensor 21A, together with the operation amount detector 7, constitutes a displacement detection means for detecting the relative displacement between the booster piston 18 and the input rod 19, and these detection signals are sent to the first ECU 26. The motor position detection means (rotation detection means) is not limited to the rotation sensor 21A such as a resolver, but may be constituted by a rotary potentiometer or the like that can detect absolute displacement (angle).

  The speed reduction mechanism 23 is not limited to a belt or the like, and may be configured using, for example, a gear speed reduction mechanism. Further, the linear motion mechanism 24 that converts the rotational motion into the linear motion can also be configured by a rack-pinion mechanism or the like, for example. Further, the speed reduction mechanism 23 is not necessarily provided. For example, the motor shaft is integrally provided on the cylindrical rotating body 22, the stator of the electric motor is arranged around the cylindrical rotating body 22, and directly by the electric motor. The cylindrical rotating body 22 may be rotated as a rotor.

  The first ECU 26 is composed of, for example, a microcomputer, and constitutes a part of the electric booster 16 and also constitutes control means for the electric booster 16. The first ECU 26 constitutes a master pressure control unit (that is, a first control circuit) that electrically drives and controls the electric actuator 20 of the electric booster 16. The input side of the first ECU 26 can communicate with an operation amount detector 7 for detecting an operation amount or a pedaling force of the brake pedal 5, a rotation sensor 21A and a current sensor 21B of the electric motor 21, for example, L-CAN. It is connected to the in-vehicle signal line 27 and a vehicle data bus 28 for transmitting / receiving signals from ECUs of other vehicle devices.

  The vehicle data bus 28 is a serial communication unit called V-CAN mounted on the vehicle, and performs multiplex communication for in-vehicle use. Further, the first ECU 26 is supplied with electric power from an in-vehicle battery (not shown) through a power line 52 described later. In FIG. 1 and FIG. 2, two hatched lines represent electrical lines such as signal lines and power supply lines.

  The hydraulic pressure sensor 29 constitutes hydraulic pressure detecting means for detecting the brake hydraulic pressure of the master cylinder 8. This hydraulic pressure sensor 29 detects, for example, the hydraulic pressure in the cylinder side hydraulic pipe 15A, and detects the brake hydraulic pressure supplied from the master cylinder 8 to the ESC 30 described later via the cylinder side hydraulic pipe 15A. . In the present embodiment, the hydraulic pressure sensor 29 is electrically connected to a second ECU 32 to be described later, and a detection signal from the hydraulic pressure sensor 29 is sent from the second ECU 32 via the signal line 27 to the first ECU 32. Also sent to the ECU 26 by communication.

  In addition, it is good also as a structure which provides the hydraulic pressure sensor 29 in both cylinder side hydraulic piping 15A, 15B, respectively. Further, the hydraulic pressure sensor 29 may be directly attached to the cylinder body 9 of the master cylinder 8 as long as it can detect the brake hydraulic pressure of the master cylinder 8. Further, the hydraulic pressure sensor 29 may be configured so that the detection signal can be directly input to the first ECU 26 without going through the second ECU 32.

  The output side of the first ECU 26 is connected to the electric motor 21, the in-vehicle signal line 27, the vehicle data bus 28, and the like. Then, the first ECU 26 is generated in the master cylinder 8 by the electric actuator 20 in accordance with detection signals from the operation amount detector 7, the rotation sensor 21 </ b> A and the hydraulic pressure sensor 29 (that is, the operation amount, the motor position and the brake hydraulic pressure). The brake fluid pressure to be controlled is variably controlled and also has a function of determining whether or not the electric booster 16 is operating normally.

  In the electric booster 16, when the brake pedal 5 is depressed, the input rod 19 moves forward into the cylinder body 9 of the master cylinder 8, and the movement at this time is the operation amount by the operation amount detector 7. Detected. The first ECU 26 outputs a start command to the electric motor 21 by a detection signal from the operation amount detector 7 to drive the electric motor 21 to rotate, and the rotation is transmitted to the cylindrical rotating body 22 via the speed reduction mechanism 23. At the same time, the rotation of the cylindrical rotating body 22 is converted into the axial displacement of the booster piston 18 by the linear motion mechanism 24.

  At this time, the booster piston 18 advances integrally with the input rod 19 (or with relative displacement as described later) toward the cylinder body 9 of the master cylinder 8 and is applied to the input rod 19 from the brake pedal 5. Brake fluid pressure corresponding to the pedal force (thrust) and the booster thrust applied from the electric actuator 20 to the booster piston 18 is generated in the first and second fluid pressure chambers 11A and 11B of the master cylinder 8. Further, the first ECU 26 can monitor the hydraulic pressure generated in the master cylinder 8 by receiving the detection signal from the hydraulic pressure sensor 29 from the signal line 27, and the electric booster 16 operates normally. It can be determined whether or not.

  Next, the hydraulic pressure supply device 30 (that is, the ESC 30) as the second braking mechanism will be described with reference to FIG.

  The hydraulic pressure supply device 30 as an ESC is provided between the wheel cylinders 3L, 3R, 4L, 4R and the master cylinder 8 disposed on the vehicle wheels (front wheels 1L, 1R and rear wheels 2L, 2R). It has been. The hydraulic pressure supply device 30 variably controls the brake hydraulic pressure generated in the master cylinder 8 (first and second hydraulic pressure chambers 11A and 11B) by the electric booster 16 as the wheel cylinder pressure for each wheel. The wheel cylinder pressure control device is configured to be individually supplied to the wheel cylinders 3L, 3R, 4L, and 4R of each wheel.

  That is, the hydraulic pressure supply device 30 performs various types of brake control (for example, braking force distribution control for distributing braking force to the front wheels 1L and 1R, the rear wheels 2L and 2R, antilock brake control, vehicle stabilization control, etc.). In each case, the necessary brake fluid pressure is supplied from the master cylinder 8 to the wheel cylinders 3L, 3R, 4L, 4R via the cylinder side fluid pressure pipes 15A, 15B and the like.

  Here, the hydraulic pressure supply device 30 supplies the hydraulic pressure output from the master cylinder 8 (first and second hydraulic pressure chambers 11A and 11B) via the cylinder-side hydraulic piping 15A and 15B to the brake-side piping section. Distribution and supply to the wheel cylinders 3L, 3R, 4L and 4R via 31A, 31B, 31C and 31D. Thus, as described above, independent braking forces are individually applied to the respective wheels (front wheels 1L, 1R, rear wheels 2L, 2R). The hydraulic pressure supply device 30 includes control valves 37, 37 ', 38, 38', 39, 39 ', 42, 42', 43, 43 ', 50, 50' and hydraulic pumps 44, 44 ', which will be described later. Is configured to include a hydraulic control reservoir 49, 49 'and the like.

  The second ECU 32 is a hydraulic pressure supply device controller as a wheel pressure control unit (that is, a second control circuit) that electrically drives and controls the hydraulic pressure supply device 30. The input side of the second ECU 32 is connected to the hydraulic pressure sensor 29, the signal line 27, the vehicle data bus 28, and the like. The output side of the second ECU 32 includes control valves 37, 37 ', 38, 38', 39, 39 ', 42, 42', 43, 43 ', 50, 50', an electric motor 45, a signal line, which will be described later. 27 and the vehicle data bus 28 and the like.

  Here, the second ECU 32 includes the control valves 37, 37 ′, 38, 38 ′, 39, 39 ′, 42, 42 ′, 43, 43 ′, 50, 50 ′ of the hydraulic pressure supply device 30 and the electric motor. 45 and the like are individually driven and controlled as described later. As a result, the second ECU 32 controls the wheel cylinders 3L, 3R to reduce, hold, increase or increase the brake fluid pressure supplied to the wheel cylinders 3L, 3R, 4L, 4R from the brake side piping portions 31A to 31D. 4L and 4R are performed separately.

  That is, the second ECU 32 controls the hydraulic pressure supply device 30 (ESC) to control, for example, braking force distribution control, antilock brake control, vehicle stabilization control that stabilizes the behavior of the vehicle, slope start assist control, It performs traction control, vehicle following control, lane departure avoidance control, obstacle avoidance control, and the like.

  The hydraulic pressure supply device 30 is connected to one output port of the master cylinder 8 (that is, the cylinder side hydraulic pipe 15A) and is connected to the left front wheel (FL) side wheel cylinder 3L and the right rear wheel (RR) side wheel cylinder. The first hydraulic system 33 for supplying hydraulic pressure to 4R, and the wheel cylinder 3R on the right front wheel (FR) side and the left rear wheel (RL) connected to the other output port (that is, the cylinder side hydraulic pipe 15B). ) -Side wheel cylinder 4L and a second hydraulic system 33 ′ for supplying hydraulic pressure to the wheel cylinder 4L. Here, since the first hydraulic system 33 and the second hydraulic system 33 'have the same configuration, the following description will be given only for the first hydraulic system 33, and the second hydraulic system 33'. For “”, “′” is added to the reference numerals of the respective components, and the description thereof is omitted.

  The first hydraulic system 33 of the hydraulic pressure supply device 30 includes a brake pipe 34 connected to the tip side of the cylinder side hydraulic pipe 15A. The brake pipe 34 includes the first pipe section 35 and the second pipe section 34. The two branch portions 36 are connected to the wheel cylinders 3L and 4R, respectively. The brake pipeline 34 and the first pipeline 35 constitute a pipeline that supplies the hydraulic pressure to the wheel cylinder 3L together with the brake pipeline 31A, and the brake pipeline 34 and the second pipeline 36 consist of the brake pipeline. A pipe line for supplying hydraulic pressure to the wheel cylinder 4R is configured together with the portion 31D.

  The brake pipe 34 is provided with a brake hydraulic pressure supply control valve 37, and the supply control valve 37 is a normally open electromagnetic switching valve that opens and closes the brake pipe 34. The first pipe section 35 is provided with a pressure increase control valve 38, and the pressure increase control valve 38 is constituted by a normally open electromagnetic switching valve that opens and closes the first pipe section 35. The second pipe section 36 is provided with a pressure increase control valve 39, and the pressure increase control valve 39 is constituted by a normally open electromagnetic switching valve that opens and closes the second pipe section 36.

  On the other hand, the first hydraulic system 33 of the hydraulic pressure supply device 30 has first and second pressure reducing lines 40 and 41 that connect the wheel cylinders 3L and 4R and the hydraulic pressure control reservoir 49, respectively. These pressure reducing lines 40 and 41 are provided with first and second pressure reducing control valves 42 and 43, respectively. The first and second pressure reduction control valves 42 and 43 are normally closed electromagnetic switching valves that open and close the pressure reduction lines 40 and 41, respectively.

  Further, the hydraulic pressure supply device 30 includes a hydraulic pressure pump 44 as hydraulic pressure generating means that is a hydraulic pressure source, and the hydraulic pressure pump 44 is rotationally driven by an electric motor 45. Here, the electric motor 45 is driven by the power supply from the second ECU 32, and stops rotating together with the hydraulic pump 44 when the power supply is stopped. The discharge side of the hydraulic pump 44 is positioned downstream of the supply control valve 37 in the brake line 34 via the check valve 46 (that is, the first line part 35 and the second line part 36). Is connected to the position where the The suction side of the hydraulic pump 44 is connected to a hydraulic pressure control reservoir 49 via check valves 47 and 48.

  The hydraulic pressure control reservoir 49 is provided to temporarily store surplus brake fluid, and is not limited to the ABS control of the brake system (hydraulic pressure supply device 30), and the wheel cylinder 3L, Excess brake fluid flowing out from a 4R cylinder chamber (not shown) is temporarily stored. The suction side of the hydraulic pump 44 is connected to the cylinder side hydraulic pipe 15A (that is, the brake pipe 34) of the master cylinder 8 via a check valve 47 and a pressurization control valve 50 that is a normally closed electromagnetic switching valve. Of these, it is connected to the upstream side of the supply control valve 37.

  The control valves 37, 37 ′, 38, 38 ′, 39, 39 ′, 42, 42 ′, 43, 43 ′, 50, 50 ′ and the hydraulic pumps 44, 44 ′ constituting the hydraulic pressure supply device 30 are provided. The electric motor 45 to be driven is controlled in accordance with a predetermined procedure according to a control signal output from the second ECU 32.

  That is, the first hydraulic system 33 of the hydraulic pressure supply device 30 transfers the hydraulic pressure generated in the master cylinder 8 by the electric booster 16 during the normal operation by the driver's brake operation to the brake line 34 and the first hydraulic system 33. 1. Directly supplied to the wheel cylinders 3L, 4R via the second pipe sections 35, 36. For example, when anti-skid control or the like is executed, the pressure-increasing control valves 38 and 39 are closed to hold the hydraulic pressures of the wheel cylinders 3L and 4R, and when the hydraulic pressures of the wheel cylinders 3L and 4R are reduced, the pressure-reducing control valves 42 and 43 are opened, and the hydraulic pressure in the wheel cylinders 3L and 4R is discharged so as to escape to the hydraulic pressure control reservoir 49.

  Further, when the hydraulic pressure supplied to the wheel cylinders 3L, 4R is increased in order to perform stabilization control (side slip prevention control) or the like during vehicle travel, the hydraulic pressure is controlled by the electric motor 45 with the supply control valve 37 closed. The pump 44 is operated, and the brake fluid discharged from the hydraulic pump 44 is supplied to the wheel cylinders 3L and 4R via the first and second pipe sections 35 and 36. At this time, since the pressurization control valve 50 is opened, the brake fluid in the reservoir 14 is supplied from the master cylinder 8 side to the suction side of the hydraulic pump 44.

  As described above, the second ECU 32 determines the supply control valve 37, the pressure increase control valves 38, 39, the pressure reduction control valves 42, 43, the pressure control valve 50, and the electric motor 45 (that is, liquid) based on the vehicle operation information and the like. The operation of the pressure pump 44) is controlled, and the hydraulic pressure supplied to the wheel cylinders 3L and 4R is appropriately maintained, or reduced or increased. As a result, brake control such as braking force distribution control, vehicle stabilization control, brake assist control, anti-skid control, traction control, and slope start assist control described above is executed.

  On the other hand, in a normal braking mode performed with the electric motor 45 (that is, the hydraulic pump 44) stopped, the supply control valve 37 and the pressure increase control valves 38 and 39 are opened, and the pressure reduction control valves 42 and 43 and the pressure control valves 42 and 43 are increased. The pressure control valve 50 is closed. In this state, the first piston (that is, the booster piston 18 and the input rod 19) of the master cylinder 8 and the second piston 10 are displaced in the axial direction in the cylinder body 9 in accordance with the depression operation of the brake pedal 5. Sometimes, the brake fluid pressure generated in the first fluid pressure chamber 11A is transferred from the cylinder side fluid pressure piping 15A side through the first fluid pressure system 33 and the brake side piping portions 31A and 31D of the fluid pressure supply device 30. It is supplied to the wheel cylinders 3L and 4R. The brake fluid pressure generated in the second fluid pressure chamber 11B is supplied from the cylinder side fluid pressure pipe 15B side to the wheel cylinders 3R and 4L via the second fluid pressure system 33 'and the brake side pipe portions 31B and 31C. The

  When the booster piston 18 cannot be operated by the electric motor 21 due to the failure of the electric booster 16, the brake hydraulic pressure generated in the first and second hydraulic pressure chambers 11A and 11B is sent to the second ECU 32. Detected by the connected hydraulic pressure sensor 29, assist control is performed to increase the pressure of each wheel cylinder so that the detected value becomes the wheel cylinder pressure corresponding to the detected value as the operation amount of the brake pedal 5. In the assist control, the pressurization control valve 50 and the pressure increase control valves 38 and 39 are opened, and the supply control valve 37 and the pressure reduction control valves 42 and 43 are appropriately opened and closed. In this state, the hydraulic pump 44 is operated by the electric motor 45, and the brake fluid discharged from the hydraulic pump 44 is supplied to the wheel cylinders 3L and 4R via the first and second pipe sections 35 and 36. Thereby, the braking force by the wheel cylinders 3L and 4R can be generated by the brake fluid discharged from the hydraulic pump 44 on the basis of the brake fluid pressure generated on the master cylinder 8 side.

  As the hydraulic pump 44, for example, a known hydraulic pump such as a plunger pump, a trochoid pump, a gear pump or the like can be used. As the electric motor 45, for example, a known motor such as a DC motor, a DC brushless motor, or an AC motor can be used. In the present embodiment, a DC motor is used from the viewpoint of in-vehicle performance.

  Further, the control valves 37, 38, 39, 42, 43, and 50 of the hydraulic pressure supply device 30 can have their characteristics appropriately set according to their use modes. The pressure control valves 38 and 39 are normally open valves, and the pressure reduction control valves 42 and 43 and the pressurization control valve 50 are normally closed valves, so that the master cylinder 8 can be used even when there is no control signal from the second ECU 32. Can supply hydraulic pressure to the wheel cylinders 3L to 4R. Therefore, such a configuration is desirable from the viewpoint of fail-safe and control efficiency of the brake system.

  A regenerative cooperative control device 51 for power charging is connected to the vehicle data bus 28 mounted on the vehicle. Similar to the first and second ECUs 26 and 32, the regenerative cooperative control device 51 is composed of a microcomputer or the like, and uses the inertial force generated by the rotation of each wheel when the vehicle is decelerated and braked. By controlling a drive motor (not shown), a braking force is obtained while recovering kinetic energy at this time as electric power.

  Here, the regenerative cooperative control device 51 is connected to the first ECU 26 and the second ECU 32 via the vehicle data bus 28 and constitutes a regenerative braking control means. Furthermore, the regenerative cooperative control device 51 is connected to an in-vehicle power supply line 52. The power supply line 52 supplies power from a vehicle-mounted battery (not shown) to the first and second ECUs 26 and 32, the regenerative cooperative control device 51, and the like.

  Next, the control content of the electric booster 16 by the master pressure control unit (that is, the first ECU 26) will be described with reference to FIG.

  The first ECU 26 determines a primary piston (P piston) corresponding to the control input Sx (Sx = Sa), that is, a target position of the booster piston 18 (hereinafter referred to as a target P piston position) as indicated by a characteristic line 58 shown in FIG. The target hydraulic pressure characteristic that represents the relationship between the target piston position calculation unit 53 that performs the control and the hydraulic pressure with respect to the control input Sx (Sx = Sb) (see the characteristic line 59 shown in FIG. 5) is corrected by the method described later, A target hydraulic pressure characteristic calculation unit 54 as hydraulic pressure characteristic calculation means for calculating (that is, hydraulic pressure characteristic data), and a target hydraulic pressure characteristic calculated by the target hydraulic pressure characteristic calculation unit 54 (for example, a characteristic line in FIG. 7). 61 or hydraulic pressure characteristic data by the characteristic line 62 in FIG. 8), a target hydraulic pressure calculation unit 55 as a target hydraulic pressure calculation means for calculating a target hydraulic pressure value for the control input Sb, and a control switching means. A control switching unit 56, and a motor controller 57 as a motor control means.

  The target piston position calculation unit 53, the target hydraulic pressure characteristic calculation unit 54, the target hydraulic pressure calculation unit 55, the control switching unit 56, and the motor control unit 57 are configured in a circuit as hardware of the first ECU 26. It is not a thing but is comprised as a concept of the function which 1st ECU26 has. Here, the control switching unit 56 operates the electric motor 21 based on either the target P piston position calculated by the target piston position calculation unit 53 or the target hydraulic pressure calculated by the target hydraulic pressure calculation unit 55. Is determined and control is executed. The motor control unit 57 drives and controls the electric motor 21 according to the target P piston position (or target hydraulic pressure) determined by the control switching unit 56.

  As shown in FIG. 2, the first ECU 26 is provided with a memory 26A as a storage device, and the memory 26A includes a flash memory, an EEPROM, a ROM, a RAM, and the like. In this memory 26A, for example, as shown in FIG. 4, the operation amount S of the brake pedal 5 and the booster piston 18 of the booster piston 18 with respect to the reference downstream rigidity predetermined for each vehicle on which the electric booster 16 is mounted. The characteristic data (map) of the reference position set as the characteristic line 58 with respect to the target position Po, and the relation between the operation amount S of the brake pedal 5 and the target hydraulic pressure Pr as shown in FIG. Characteristic data (map) of the reference hydraulic pressure set as follows, hydraulic pressure characteristic data (map) by characteristic lines 61 and 62 as shown in FIGS. 7 and 8, for example, and control processing shown in FIGS. And other programs are stored.

  The downstream stiffness in the state of the wheel cylinders 3L, 3R, 4L, 4R is the amount of brake fluid required and the required fluid pressure on the wheel cylinders 3L, 3R, 4L, 4R that apply braking force to the vehicle. In the wheel cylinders 3L, 3R, 4L, and 4R, it is known that the necessary fluid amount and the necessary fluid pressure with respect to the target deceleration change depending on the use situation. Specifically, the hardness of friction pads (not shown) provided on the wheel cylinders 3L, 3R, 4L, and 4R varies depending on the temperature and the degree of wear. For example, it is known that when the temperature of the friction pad increases and becomes soft, the downstream stiffness tends to decrease, and when the friction pad wears harder, the downstream stiffness tends to increase. It has been. Further, when the air bleed (air bleeding operation) of the wheel cylinders 3L, 3R, 4L, and 4R is performed, the downstream rigidity is higher than before the air bleed is performed.

  The target piston position calculation unit 53 uses, for example, the operation amount S of the brake pedal 5 as a control input Sa with respect to a preset reference downstream stiffness, and uses characteristic data (brake from the reference position characteristic line 58 shown in FIG. Data mapping the relationship of the target position Po of the booster piston 18 with respect to the operation amount S of the pedal 5) is read from the memory 26A. Then, the target piston position calculation unit 53 calculates the target P piston position (that is, the target position Po of the booster piston 18) with respect to the control input Sa using the characteristic data of the reference position.

  The target hydraulic pressure characteristic calculation unit 54 as the hydraulic pressure characteristic calculation means includes an operation amount S of the brake pedal 5 (that is, a control input Sb shown in FIG. 3) and a target P piston position output from the target piston position calculation unit 53. The operation amount for realizing the brake characteristics corresponding to the downstream rigidity (the state of the wheel cylinder) by the (ie, the motor position) and the brake fluid pressure (ie, the fluid pressure Pr) output from the fluid pressure sensor 29. Hydraulic pressure characteristic data (see, for example, the characteristic line 61 shown in FIG. 7 or the characteristic line 62 shown in FIG. 8).

  Specifically, the target hydraulic pressure characteristic calculation unit 54 uses, for example, the operation amount S of the brake pedal 5 as the control input Sb with respect to a preset reference downstream stiffness, and the reference hydraulic pressure characteristic shown in FIG. Characteristic data (relationship of the target hydraulic pressure Pr with respect to the operation amount S of the brake pedal 5) by the line 59 is read from the memory 26A. Then, the target hydraulic pressure characteristic calculation unit 54 corrects the characteristic data as described later to obtain target hydraulic pressure characteristic data (for example, hydraulic pressure characteristic data based on the characteristic line 61 in FIG. 7 or the characteristic line 62 in FIG. 8). ) Is calculated. Then, the target hydraulic pressure calculation unit 55 calculates a target hydraulic pressure value for the operation amount S (control input Sb) of the brake pedal 5 from the target hydraulic pressure characteristic data calculated by the target hydraulic pressure characteristic calculation unit 54.

  The control switching unit 56 selects either the target P piston position calculated by the target piston position calculation unit 53 or the target hydraulic pressure value calculated by the target hydraulic pressure calculation unit 55 according to a predetermined determination condition. At this time, the control switching unit 56 may limit or correct the target P piston position (or target hydraulic pressure value) according to the determination condition.

  The motor control unit 57 outputs a control drive signal to the electric motor 21 based on the target P piston position (or target hydraulic pressure value) selected by the control switching unit 56. Thereby, the motor control part 57 which is a three-phase motor control circuit controls the action | operation of the electric motor 21 of the electric booster 16 so that a target P piston position (or target hydraulic pressure value) may be obtained.

  The brake control device according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, when the driver of the vehicle depresses the brake pedal 5, the input rod 19 is pushed in the direction indicated by the arrow A, and the electric actuator 20 of the electric booster 16 is activated and controlled by the first ECU 26. . That is, the first ECU 26 outputs a start command to the electric motor 21 by a detection signal from the operation amount detector 7 to drive the electric motor 21 to rotate, and the rotation of the first ECU 26 via the speed reduction mechanism 23 causes the cylindrical rotating body 22 to rotate. And the rotation of the cylindrical rotating body 22 is converted into the axial displacement of the booster piston 18 by the linear motion mechanism 24.

  As a result, the booster piston 18 of the electric booster 16 advances substantially integrally with the input rod 19 toward the cylinder body 9 of the master cylinder 8, and a pedaling force (thrust force) applied to the input rod 19 from the brake pedal 5. ) And a booster thrust applied to the booster piston 18 from the electric actuator 20 is generated in the first and second hydraulic chambers 11A and 11B of the master cylinder 8.

  Further, the first ECU 26 monitors the hydraulic pressure generated in the master cylinder 8 by receiving the detection signal from the hydraulic pressure sensor 29 from the signal line 27, and the electric actuator 20 (of the electric motor 21 of the electric booster 16). Rotation) is feedback controlled. Thus, the first ECU 26 can variably control the brake hydraulic pressure generated in the first and second hydraulic pressure chambers 11A and 11B of the master cylinder 8 based on the depression operation amount of the brake pedal 5. it can. Further, the first ECU 26 can determine whether or not the electric booster 16 is operating normally according to detection signals from the operation amount detector 7, the rotation sensor 21 </ b> A, and the hydraulic pressure sensor 29.

  On the other hand, the input rod 19 connected to the brake pedal 5 receives the pressure in the first hydraulic chamber 11A and transmits this pressure to the brake pedal 5 as a brake reaction force. As a result, the driver of the vehicle is given a tread response through the input rod 19, thereby improving the operational feeling of the brake pedal 5 and maintaining a good pedal feeling.

  As described above, when the electric booster 16 is controlled by the first ECU 26, the electric motor 21 is operated based on the operation amount (displacement amount, stepping force, etc.) of the brake pedal 5 detected by the operation amount detector 7. Then, the position of the booster piston 18 is controlled to generate a hydraulic pressure. At this time, the hydraulic pressure generated in the master cylinder 8 (first hydraulic pressure chamber 11A) becomes a reaction force and is fed back from the input rod 19 to the brake pedal 5. Then, the boost ratio, which is the ratio between the operation amount of the brake pedal 5 and the generated hydraulic pressure, can be adjusted according to the pressure receiving area ratio between the booster piston 18 and the input rod 19 and the positional relationship of the booster piston 18 with respect to the input rod 19. it can.

  For example, by making the booster piston 18 follow the displacement of the input rod 19 and controlling the booster piston 18 so that the positional relationship of the booster piston 18 with respect to the input rod 19 becomes equal, the input rod 19 and the booster piston 18 are A constant boost ratio determined by the pressure receiving area ratio can be obtained. Further, the boost ratio can be changed by multiplying the displacement of the input rod 19 by a proportional gain to change the positional relationship of the booster piston 18 with respect to the input rod 19.

  Accordingly, the required braking force (hydraulic pressure) characteristics can be made variable with respect to the set operation amount of the brake pedal 5 in consideration of the downstream rigidity set in advance, which is required by the driver of the vehicle. The vehicle deceleration with respect to the operation amount of the brake pedal 5 can be made variable. Further, the first ECU 26 receives a CAN signal from the regenerative cooperative control device 51 (that is, the regenerative braking system) via the vehicle data bus 28, and determines whether regenerative braking is being performed based on this operation signal. In regenerative braking, regenerative coordination that adjusts the boost ratio to generate the hydraulic pressure minus the amount of regenerative braking so that the desired braking force can be obtained by the sum of the regenerative braking amount and the hydraulic braking force Control can be performed.

  Next, the hydraulic pressure supply device 30 provided between the wheel cylinders 3L, 3R, 4L, 4R on the side of each wheel (front wheels 1L, 1R and rear wheels 2L, 2R) and the master cylinder 8 is an electric booster. 16, the brake hydraulic pressure generated in the master cylinder 8 (first and second hydraulic pressure chambers 11A and 11B) is supplied from the cylinder side hydraulic pipes 15A and 15B to the hydraulic pressure systems 33 and 33 in the hydraulic pressure supply device 30. ′ And the brake cylinders 31A, 31B, 31C, 31D, while being variably controlled to the wheel cylinders 3L, 3R, 4L, 4R, it is distributed and supplied as wheel cylinder pressure for each wheel. As a result, an appropriate braking force is applied to the vehicle wheels (respective front wheels 1L, 1R, rear wheels 2L, 2R) via the wheel cylinders 3L, 3R, 4L, 4R.

  Here, the second ECU 32 that controls the hydraulic pressure supply device 30 can monitor the depression operation amount of the brake pedal 5 by receiving the detection signal from the operation amount detector 7 from the signal line 27. The brake fluid pressure can be continuously monitored by the detection signal from the sensor 29. When the brake is operated, the control signal is output from the second ECU 32 to the electric motor 45 by receiving the detection signal from the operation amount detector 7, and the hydraulic pumps 44 and 44 'can be operated. The control valves 37, 37 ', 38, 38', 39, 39 ', 42, 42', 43, 43 ', 50, 50' can be selectively opened and closed.

  For this reason, when braking the vehicle, the brake hydraulic pressure supplied from the master cylinder 8 (and / or the hydraulic pumps 44, 44 ') to the wheel cylinders 3L, 3R, 4L, 4R according to the depression operation of the brake pedal 5, respectively. The brake fluid pressure corresponding to the depression operation of the brake pedal 5 and the driving state of the vehicle can be supplied to the wheel cylinders 3L, 3R, 4L, 4R and the vehicle control Power control can be performed with high accuracy.

  Next, drive control of the electric motor 21 by the first ECU 26 (that is, control processing of the electric motor 21 according to the operation amount S of the brake pedal 5) will be described with reference to FIG. The first ECU 26 controls the electric motor 21 of the electric actuator 20 as a means for controlling the piston position according to the target piston position, and the hydraulic pressure for controlling the brake hydraulic pressure according to the target hydraulic pressure. Control function.

  When the first ECU 26 performs piston position control, for example, the operation amount S of the brake pedal 5 is used as the control input Sa, and the target piston position calculation unit 53 uses the target P of the booster piston 18 with respect to the operation amount S of the brake pedal 5. The target position Poa of the booster piston 18 is calculated with respect to the control input Sa from the reference position characteristic (characteristic line 58 shown in FIG. 4) representing the relationship between the piston position (that is, the target position Po).

  When the first ECU 26 performs hydraulic pressure control, for example, the operation amount S of the brake pedal 5 is used as the control input Sb, and the target hydraulic pressure characteristic calculation unit 54 sets the target hydraulic pressure Pr with respect to the operation amount S of the brake pedal 5. Reference hydraulic pressure characteristics (characteristic line 59 shown in FIG. 5) representing the relationship are corrected by a method described later (characteristic lines 59 and 60 shown in FIG. 6) to calculate target hydraulic pressure characteristic data. Then, the target hydraulic pressure calculation unit 55 calculates a target hydraulic pressure value corresponding to the control input Sb (operation amount S) from the target hydraulic pressure characteristic data calculated by the target hydraulic pressure characteristic calculation unit 54.

  Here, the piston position control only controls the piston position of the booster piston 18 (that is, the rotational position of the electric motor 21) in correspondence with the operation amount S of the brake pedal 5, and the brake fluid pressure during this period is Feedback control is not performed according to the detection signal (detection pressure) of the hydraulic pressure sensor 29. For this reason, the brake characteristic by the piston position control becomes a characteristic of the hydraulic pressure generated according to the amount of brake fluid sent into the master cylinder 8, and this characteristic (hydraulic pressure value) changes according to the downstream rigidity as a result. . Thereafter, when the piston position control is performed, the hydraulic pressure generated according to the operation amount S has a hydraulic pressure characteristic that changes according to the downstream rigidity.

  On the other hand, when the hydraulic pressure control is performed, the hydraulic pressure Pr shown in FIG. 5 is controlled with respect to the operation amount S of the brake pedal 5 (that is, feedback control is performed according to the detection signal from the hydraulic pressure sensor 29). When the characteristic of the target hydraulic pressure with respect to the amount S (for example, the characteristic line 59) is fixed, the hydraulic pressure Pr generated according to the operation amount S (that is, the brake hydraulic pressure detected by the hydraulic pressure sensor 29) is reduced to the downstream rigidity. Regardless of the control, it is controlled so as to have a fixed hydraulic pressure value. Therefore, it is necessary to change the target hydraulic pressure in accordance with the downstream rigidity so that the hydraulic pressure characteristic becomes the downstream rigidity even during the hydraulic pressure control. That is, in order to realize the original target hydraulic pressure, it is necessary to correct the rotation control of the electric motor 21 that moves the booster piston 18 forward and backward so that a necessary amount of brake fluid can be generated according to the change in downstream rigidity. is there.

  Further, as described above, during regenerative cooperative control, the regenerative braking amount is subtracted from the master cylinder 8 so that the total value of the braking force due to regeneration and the braking force due to hydraulic pressure matches the desired braking force by the driver. It is necessary to generate a hydraulic pressure. However, when the piston position control is performed, the hydraulic pressure (that is, the braking force) generated at this time changes according to the downstream rigidity, and therefore the braking force to be generated with respect to the operation amount S of the brake pedal 5 is set. It becomes difficult to make a decision, and regenerative cooperative control cannot actually be performed. On the other hand, when performing hydraulic pressure control, since hydraulic pressure (namely, braking force) is determined with respect to the operation amount S, regenerative cooperative control can be performed during hydraulic pressure control.

  Therefore, the first ECU 26 performs the piston position control by the control switching unit 56 until the hydraulic pressure characteristic corresponding to the downstream rigidity is obtained in order to perform the regenerative cooperative control while setting the hydraulic characteristic corresponding to the downstream rigidity. After that, after the hydraulic pressure characteristic corresponding to the downstream rigidity (that is, the hydraulic pressure characteristic data corresponding to the downstream rigidity as shown by a solid line 60 in FIG. 6 to be described later) can be calculated, the control switching unit 56 The control is switched between the target piston position calculation unit 53 and the target hydraulic pressure calculation unit 55 so as to switch to the hydraulic pressure control. At this time, the control switching unit 56 may limit or correct the target piston position and the target hydraulic pressure value.

  The motor control unit 57 operates the electric motor 21 of the electric booster 16 so that the target piston position or the target hydraulic pressure value is achieved based on the target piston position or the target hydraulic pressure selected by the control switching unit 56. To control. At this time, the brake fluid pressure generated in the master cylinder 8 is determined by the amount of movement of the input rod 19 corresponding to the operation of the brake pedal 5 (that is, the amount of pedal operation) and the movement of the booster piston 18 corresponding to the operation of the electric motor 21. It is increased or decreased depending on the amount.

  Next, a method of calculating the target hydraulic pressure characteristic (that is, hydraulic pressure characteristic data corresponding to the downstream stiffness) used by the target hydraulic pressure characteristic calculation unit 54 will be described with reference to FIGS. 3, 5, and 6.

  First, the target piston position calculation unit 53 shown in FIG. 3 performs piston position control according to the operation amount S, and when the brake hydraulic pressure generated in the master cylinder 8 becomes a preset switching reference hydraulic pressure Pk, the target The hydraulic pressure characteristic calculation unit 54 calculates the switching reference operation amount Sk for the switching reference hydraulic pressure Pk from the characteristic line 59 using the reference hydraulic pressure characteristic shown in FIG. That is, when the brake hydraulic pressure of the master cylinder 8 detected by the hydraulic pressure sensor 29 reaches the switching reference hydraulic pressure Pk, the target hydraulic pressure characteristic calculation unit 54 calculates the switching reference hydraulic pressure from the characteristic line 59 shown in FIG. A switching reference operation amount Sk with respect to Pk is calculated.

  Next, as shown in FIG. 6, the target hydraulic pressure characteristic calculation unit 54 calculates the difference between the switching reference operation amount Sk and the actual operation amount S1 of the brake pedal 5 (actual operation amount detected by the operation amount detector 7). Is calculated as a switching operation amount deviation ΔS (ΔS = S1−Sk). The actual operation amount S1 of the brake pedal 5 corresponds to the control input Sb input to the target hydraulic pressure characteristic calculation unit 54 in FIG.

  The switching reference hydraulic pressure Pk is set to a hydraulic pressure value at which the change characteristic of the fluid with respect to the change in the operation amount S after the switching reference hydraulic pressure Pk can allow the change due to the downstream rigidity. In this case, as a specific example of the switching reference hydraulic pressure Pk, the first supply port 9A shown in FIG. 2 is blocked from the first hydraulic pressure chamber 11A by the booster piston 18, and the second supply port 9B is set to the second supply port 9B. It is possible to set the hydraulic pressure value so that the hydraulic pressure sensor 29 can detect that the brake fluid pressure is started to be generated from the master cylinder 8 by being cut off from the second hydraulic pressure chamber 11B by the piston 10.

  Then, the target hydraulic pressure characteristic calculation unit 54 displays the hydraulic pressure characteristic obtained by offsetting the characteristic line 59 indicated by the dotted line in FIG. 6 in the direction of the operation amount S by the switching operation amount deviation ΔS in FIG. It is calculated as target hydraulic pressure characteristic data as indicated by a characteristic line 60 indicated by a solid line. Further, the switching operation amount deviation ΔS obtained by calculation as described above and the hydraulic pressure characteristic data by the characteristic line 60 are stored in the memory 26A in an updatable manner. If the hydraulic pressure characteristic data exemplified by the characteristic line 60 does not coincide with the characteristic when the hydraulic pressure is actually generated by the piston position control, the characteristic when the hydraulic pressure is actually generated by the piston position control. The hydraulic pressure characteristic data may be corrected so as to match.

  Here, the target hydraulic pressure characteristic calculation unit 54 performs the hydraulic pressure characteristic data calculation process using the characteristic line 60 illustrated in FIG. 6 only when a predetermined condition is satisfied, and at other times (for example, downstream stiffness) Is substantially unchanged), the hydraulic pressure characteristic data obtained up to the previous time is used. As a result, when the target hydraulic pressure characteristic calculation unit 54 calculates the hydraulic pressure characteristic data, the hydraulic pressure is switched in accordance with the operation of the brake pedal 5 as indicated by a characteristic line 61 shown by a solid line in FIG. The piston position is controlled until the reference hydraulic pressure Pk is reached, and thereafter, the target hydraulic pressure characteristic data calculated as described above (for example, the target hydraulic pressure characteristic data along the characteristic line 60 shown in FIG. 6). The control switching unit 56 performs control switching between the target piston position calculation unit 53 and the target hydraulic pressure calculation unit 55 so as to perform the hydraulic pressure control based on the above.

  On the other hand, the target hydraulic pressure characteristic calculation unit 54 does not perform the calculation process of the target hydraulic pressure characteristic data (that is, the case where the predetermined condition described above is not satisfied. For example, the downstream rigidity changes substantially. When the pedal is not operated), the hydraulic pressure control is performed immediately after the start of the pedal operation using the already calculated target hydraulic pressure characteristic data as indicated by the solid line 62 in FIG. Control switching to the target hydraulic pressure calculation unit 55 is performed by the control switching unit 56.

  When the hydraulic pressure control is performed according to the target hydraulic pressure characteristic data by the characteristic line 62 shown in FIG. 8, the booster piston 18 is connected to the axis of the master cylinder 8 in the region where the hydraulic pressure Pr is zero with respect to the operation amount S. There is a possibility that the booster piston 18 suddenly starts moving at the moment when the hydraulic pressure is generated without moving in the direction. In order to prevent such a movement of the booster piston 18, the booster piston 18 may be moved by the Biston position control until a hydraulic pressure is generated, if necessary.

  Thus, in the present embodiment, every time the driver depresses the brake pedal 5 (that is, at the time of boost operation by the electric booster 16), the target hydraulic pressure characteristic calculation unit 54 calculates hydraulic pressure characteristic data. It is determined according to a predetermined condition (for example, a criterion for determining whether or not the downstream stiffness has changed). When it is not necessary to newly calculate the target hydraulic pressure characteristic data, the previous hydraulic pressure characteristic data or past data used at the time of the previous brake pedal operation is used as the target hydraulic pressure calculation unit 55 (see FIG. 3). ) Is used as the target hydraulic pressure characteristic data.

  On the other hand, when a predetermined condition (for example, a determination condition such that the downstream stiffness is changed) is satisfied when the brake pedal is operated, the target hydraulic pressure characteristic calculation unit 54 newly performs a calculation process of hydraulic pressure characteristic data. Whether the newly calculated hydraulic pressure characteristic data (hereinafter referred to as hydraulic pressure characteristic calculation data) is adopted by the target hydraulic pressure calculation unit 55 as the target hydraulic pressure characteristic data in accordance with the control processing shown in FIGS. I decide to decide. Therefore, in the following description, the hydraulic pressure characteristic data calculated by the target hydraulic pressure characteristic calculation unit 54 is referred to as “hydraulic pressure characteristic calculation data”, and the target hydraulic pressure characteristic data adopted by the target hydraulic pressure calculation unit 55 is used. Is expressed separately from “hydraulic characteristic storage data”.

  Next, among the hydraulic pressure characteristic calculation data calculated by the target hydraulic pressure characteristic calculation unit 54 when the brake pedal 5 is depressed, any one is adopted (determined) as the target hydraulic pressure characteristic data by the target hydraulic pressure calculation unit 55. The processing procedure of whether to do is demonstrated with reference to the flowchart of FIGS. 9-11.

  First, when the processing operation shown in FIG. 9 starts, the past hydraulic pressure characteristic storage data is read out from, for example, the memory 26A in step 1. The hydraulic pressure characteristic storage data is hydraulic pressure characteristic data (for example, data based on the characteristic line 62 shown in FIG. 8) that is stored in the memory 26A in an updatable manner, and is a target hydraulic pressure calculation unit at the previous brake pedal operation. This is the target hydraulic pressure characteristic data adopted in 55, or hydraulic pressure characteristic storage data stored in advance as initial data at the stage of a new vehicle.

  In the next step 2, it is determined whether or not the hydraulic pressure characteristic data has been calculated by the target hydraulic pressure characteristic calculator 54. That is, the determination process of step 2 constitutes a hydraulic pressure characteristic data calculation completion determination means, and the “hydraulic pressure characteristic calculation data” already calculated by the target hydraulic pressure characteristic calculator 54 at the start of operation of the brake pedal 5 is It is determined whether or not it is stored (saved) in the memory 26A. When it is determined as “NO” in step 2, the process proceeds to the next step 3 where the target hydraulic pressure characteristic calculation unit 54 performs a calculation process of hydraulic pressure characteristic data as indicated by a characteristic line 60 shown in FIG. Create hydraulic pressure characteristic calculation data.

  Here, the case where “NO” is determined in step 2 is a case where the first brake pedal operation is performed after the electric booster 16 is started by starting the engine (not shown) of the vehicle. As an example. In such a case, the target piston position calculation unit 53 side is selected by the control switching unit 56 shown in FIG. 3 until the calculation processing of the hydraulic pressure characteristic calculation data is completed by the target hydraulic pressure characteristic calculation unit 54 in step 3. The And the motor control part 57 implements piston position control which controls the piston position of the booster piston 18 according to the operation amount S (control input Sa) of the brake pedal 5.

  That is, in such a case, as shown by the characteristic line 61 shown in FIG. 7, for example, the piston position control is performed until the brake hydraulic pressure generated in the master cylinder 8 reaches the switching reference hydraulic pressure Pk, and the switching reference hydraulic pressure is After reaching Pk (that is, after the hydraulic pressure characteristic corresponding to the downstream stiffness can be calculated), the target piston position calculation unit 53 calculates the target hydraulic pressure so that the control switching unit 56 switches to the hydraulic pressure control. Control switching to the unit 55 is performed. And the motor control part 57 controls the action | operation of the electric motor 21 so that it may become the target hydraulic pressure value along the characteristic line 61 shown, for example in FIG.

  However, if the brake pedal operation by the driver is terminated (the pedal operation is released) while the calculation process of the hydraulic pressure characteristic calculation data is being performed by the target hydraulic pressure characteristic calculation unit 54 in step 3, the hydraulic pressure characteristic calculation is performed. The data calculation process is determined as incomplete. Therefore, when the brake pedal is operated next time, “NO” is determined in Step 2, and the processing after Step 3 (that is, calculation processing of hydraulic pressure characteristic calculation data by the target hydraulic pressure characteristic calculation unit 54) is performed from the beginning. It will be.

  Next, when the calculation process of the hydraulic pressure characteristic calculation data is completed in step 3, the process proceeds to step 4 to determine whether or not “the absolute value of the difference is within a predetermined threshold”. In other words, the process of step 4 has a function as a difference calculation means, and the difference between the hydraulic pressure characteristic calculation data previously calculated in step 3 and the past hydraulic pressure characteristic storage data (see step 1) is used as an absolute value. Calculate. Then, in step 4, it is determined whether or not the absolute value of the difference is within a predetermined threshold range. Here, the determination process of step 4 is a process for determining, for example, whether or not the downstream stiffness has changed greatly based on the absolute value of the difference.

  For example, when the calipers of the wheel cylinders 3L, 3R, 4L, 4R are replaced, the friction pads are replaced, or the air bleed is performed, the downstream stiffness may change greatly. The value is greater than a predetermined threshold. Accordingly, in this case, in order to update and rewrite past hydraulic pressure characteristic data (including hydraulic pressure characteristic storage data), it is determined as “NO” in step 4, and a large difference process is performed in step 10 described later. On the other hand, if the absolute value of the difference is within a predetermined threshold, it can be determined that the downstream stiffness has not changed significantly, and the past hydraulic pressure characteristic data need not necessarily be updated and rewritten.

  Therefore, if “YES” is determined in step 4, the calculation process of the hydraulic pressure characteristic calculation data is completed by the target hydraulic pressure characteristic calculation unit 54 after the electric booster 16 is started in the next step 5 (that is, In the determination process of step 2 (calculation completion determination means) performed through step 7 thereafter, setting is made so as to determine “YES” (for example, setting by flag processing) )

  In the next step 6, the hydraulic pressure characteristic calculation data calculated in step 3 is compared with past hydraulic pressure characteristic storage data (see step 1), and the brake characteristic becomes lower (that is, the operation amount of the brake pedal 5). The hydraulic pressure characteristic data of the lower target hydraulic pressure value for S) is written in the memory 26A as the target hydraulic pressure characteristic data adopted by the target hydraulic pressure calculation unit 55. In this case, the control switching unit 56 switches from the piston position control to the hydraulic pressure control, and the fluid according to the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data adopted by the target hydraulic pressure calculation unit 55. Perform pressure control. Then, in the next step 7, the process returns.

  That is, taking the characteristic line 61 shown in FIG. 7 as an example, the piston position control is performed as described above until the brake fluid pressure generated in the master cylinder 8 reaches the switching reference fluid pressure Pk, and the switching reference fluid is When the pressure Pk is reached, control switching is performed from the target piston position calculation unit 53 to the target hydraulic pressure calculation unit 55 so that the control switching unit 56 switches to hydraulic pressure control thereafter. Then, the motor control unit 57 controls the operation of the electric motor 21 of the electric booster 16 so that the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data adopted by the target hydraulic pressure calculation unit 55 is obtained.

  Here, the reason why the target hydraulic pressure calculation unit 55 adopts the hydraulic pressure characteristic data with the lower brake characteristic in the process of step 6 depends on the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data. This is because the hydraulic pressure control is performed on the safer side when the hydraulic pressure control is performed. That is, if the booster piston 18 moves excessively toward the bottom side of the cylinder body 9 while driving the electric motor 21 with hydraulic control in response to the operation of the brake pedal 5, Even when a higher target hydraulic pressure value is required, no more liquid can be generated from the master cylinder 8.

  Therefore, in order to reduce the possibility of such a situation, the hydraulic pressure characteristic data with the lower brake characteristic is adopted in the process of step 6 to suppress excessive movement of the booster piston 18. For this reason, it is conceivable that the brake characteristic is excessively lowered by repeating the process of step 6. However, in such a case, for example, in Steps 10 to 13, a large difference process or the like is performed as described later. Therefore, the hydraulic pressure characteristic data adopted by the target hydraulic pressure calculation unit 55 is data reflecting changes in downstream stiffness. The correction is gradually made. Then, the hydraulic pressure characteristic data reflecting the change in the downstream rigidity is stored in the memory 26A as the target hydraulic pressure characteristic storage data.

  On the other hand, when “YES” is determined in Step 2, it is determined in next Step 8 whether or not the downstream stiffness has changed. This determination process will be described later with reference to FIG. However, when “NO” is determined in Step 8, the downstream stiffness is not substantially changed. For this reason, in the next step 9, the hydraulic pressure characteristic storage data used at the time of the previous brake pedal operation is adopted. Then, the control switching unit 56 selects the hydraulic pressure control, and the motor control unit 57 performs the hydraulic pressure control immediately after the brake pedal operation is started, for example, as indicated by the characteristic line 62 shown in FIG.

  If “NO” is determined in Step 4, it can be determined that the absolute value of the difference is greater than a predetermined threshold value, and there is a high possibility that the downstream stiffness has changed significantly. That is, in such a case, since it is necessary to update and rewrite the past hydraulic pressure characteristic storage data, the subsequent large difference process is executed in the next step 10. In the next step 11, whether or not the hydraulic pressure characteristic calculation data is usable is determined according to the determination process in step 10 according to a flag process described later. While “NO” is determined in step 11, the hydraulic pressure characteristic data (including hydraulic pressure characteristic storage data) used at the time of the previous brake pedal operation by the process of step 9 is adopted. In this case, since the calculation processing of the hydraulic pressure characteristic calculation data has already been completed by the target hydraulic pressure characteristic calculation unit 54 in step 3 and the brake hydraulic pressure has reached the switching reference hydraulic pressure Pk, for example, the characteristic shown in FIG. As indicated by the line 61, the hydraulic pressure control after reaching the switching reference hydraulic pressure Pk is performed based on the previous hydraulic pressure characteristic data.

  On the other hand, when “YES” is determined in step 11, it can be determined that the hydraulic pressure characteristic calculation data calculated in step 3 can be used. Therefore, in the next step 12, the target hydraulic pressure characteristic calculation unit 54 performs the determination. It is assumed that the calculation process of the hydraulic pressure characteristic calculation data is completed (that is, the hydraulic pressure characteristic data has been calculated). In the next step 13, the current hydraulic pressure characteristic calculation data calculated in step 3 is written into the memory 26 </ b> A as target hydraulic pressure characteristic data adopted by the target hydraulic pressure calculation unit 55. In this case, the control switching unit 56 switches from the piston position control to the hydraulic pressure control, and the fluid according to the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data adopted by the target hydraulic pressure calculation unit 55. Perform pressure control. Then, in the next step 7, the process returns.

  Next, the large difference process in step 10 will be described with reference to FIG. When the processing operation of FIG. 10 is started, in step 21, the hydraulic pressure characteristic calculation data calculated in the previous step 3 is stored in the memory 26A. Note that the hydraulic pressure characteristic calculation data stored in step 21 is different from the hydraulic pressure characteristic storage data read from the memory 26A in the previous step 1, and is a past predetermined number of times (program cycle). Each data is stored in the memory 26A.

  Here, the processing in step 21 constitutes characteristic calculation data storage means, and this characteristic calculation data storage means continuously executes the absolute value of the difference calculated by the difference calculation means in step 4 a predetermined number of times. A plurality of hydraulic pressure characteristic calculation data calculated by the target hydraulic pressure characteristic calculation unit 54 (the past data for the predetermined number of times) are stored while it is determined that the threshold value is larger than the threshold value.

  In the next step 22, it is determined whether or not the absolute value of the difference is continuously greater than a predetermined threshold value. Thus, after “NO” is determined in Step 4, it is possible to determine whether or not the large difference process in Step 10 has been performed during the previous brake pedal operation. When the determination in step 22 is “NO”, the absolute value of the difference is not continuously greater than the threshold value, and therefore the hydraulic pressure characteristic calculation data in step 3 cannot be used in the next step 23. For example, flag processing is performed. Then, in the next step 24, the process returns.

  On the other hand, if “YES” is determined in Step 22, the absolute value of the difference is continuously larger than the threshold value. Therefore, in the next step 25, it is determined whether or not the number of times that the large difference process in step 10 has been performed is a predetermined number (for example, about 3 to 10 times). While it is determined as “NO” in step 25, the predetermined number of times has not been reached. Therefore, the process proceeds to step 23, and the hydraulic pressure characteristic calculation data cannot be used, for example, flag processing is performed. Then, in the next step 24, the process returns.

  On the other hand, if “YES” is determined in step 25, the absolute value of the difference is continuously greater than the threshold value a predetermined number of times. In this case, the calculation is repeated in step 26 and in step 3 above. Then, it is determined whether or not the variation in the past (predetermined number of times) hydraulic pressure characteristic calculation data stored in step 21 is within a predetermined range. When it is determined as “YES” in step 26, it can be determined that the variation of the past hydraulic pressure characteristic calculation data for a predetermined number of times is within a predetermined range. That is, the plurality of hydraulic pressure characteristic calculation data calculated by the target hydraulic pressure characteristic calculation unit 54 (past data for the predetermined number of times) does not vary greatly, and the hydraulic pressure characteristic calculation correctly reflects the change in downstream stiffness. It can be judged as data. In other words, since the hydraulic pressure characteristic calculation data is downstream rigidity, in the next step 27, for example, flag processing is performed on the assumption that the latest hydraulic pressure characteristic calculation data calculated in step 3 can be used. Then, in the next step 24, the process returns.

  On the other hand, if “NO” in step 26, that is, if it is determined that the fluctuation of the past hydraulic pressure characteristic calculation data for a predetermined number of times is outside the predetermined range, the hydraulic pressure characteristic calculation data calculated repeatedly in step 3. However, there is a possibility that it is not calculated by correctly reflecting the downstream rigidity. Therefore, in this case, the process proceeds to step 23, and the hydraulic pressure characteristic calculation data is not usable, and for example, flag processing is performed. Then, in the next step 24, the process returns.

  Here, the processing of the step 11 shown in FIG. 9 will be described. When the flag processing that the hydraulic pressure characteristic calculation data cannot be used is performed in the step 23, it is determined as “NO” in the step 11, and in this case Adopts the hydraulic pressure characteristic storage data used in the next step 9 when the brake pedal was operated last time. As a result, the control switching unit 56 selects the hydraulic pressure control, and the motor control unit 57 performs the hydraulic pressure control after reaching the switching reference hydraulic pressure Pk, for example, as shown by the characteristic line 61 shown in FIG. Based on characteristic data.

  On the other hand, when the flag processing that the hydraulic pressure characteristic calculation data is usable is performed in step 23, it is determined as “YES” in step 11, and in this case, the processing in steps 12 and 13 described above is performed. To do. That is, the current hydraulic pressure characteristic calculation data calculated in step 3 (that is, the latest hydraulic pressure characteristic calculation data) is adopted as hydraulic pressure characteristic storage data. For example, as shown by a characteristic line 61 shown in FIG. The unit 57 performs hydraulic pressure control after reaching the switching reference hydraulic pressure Pk based on the previous hydraulic pressure characteristic data.

  Next, the downstream rigidity determination process performed in step 8 when it is determined “YES” in step 2 will be described with reference to FIG. The process of step 8 is a wheel cylinder for determining whether or not the downstream rigidity (the state of the wheel cylinder) has changed after performing the calculation process of the hydraulic pressure characteristic calculation data in step 3 (hydraulic pressure characteristic calculation means). It constitutes state determination means.

  When the processing operation of FIG. 11 is started, first, in step 31, the downstream stiffness comparison data is read. Here, at the time when the process of step 8 is performed, it is not determined which one of the piston position control and the hydraulic pressure control is selected by the control switching unit 56, and no brake hydraulic pressure is generated. As the data, for example, the characteristics of the amount of fluid sent to the master cylinder 8 during the previous brake pedal operation and the generated brake fluid pressure are used. Specifically, the hydraulic pressure characteristic data determined to have been calculated in step 2 (for example, the hydraulic pressure characteristic storage data used during the previous brake pedal operation such as the characteristic line 62 shown in FIG. 8) is used. Can do.

  However, if regenerative cooperative control is performed during the previous brake pedal operation, there is a possibility that no fluid pressure is generated even when the brake pedal is operated, and the previous data without the fluid pressure may not be used. In such a case, the electric motor 21 is operated to move the booster piston 18 by a predetermined stroke regardless of the driver's operation of the brake pedal 5 while the vehicle is stopped. The hydraulic pressure characteristics of the brake hydraulic pressure and the stroke amount at this time (that is, the rotation amount of the electric motor 21 and corresponding to the liquid amount sent from the master cylinder 8) are acquired, and this is used as the comparison data of the downstream rigidity. Also good.

  In the next step 32, the past data of the downstream stiffness stored in the memory 26A in the process of step 36 described later is read. If the process of step 32 is performed in the first program cycle, the hydraulic pressure characteristic storage data read in step 1 may be read in step 32 as past data of downstream stiffness.

  In the next step 33, the comparison data of the downstream stiffness read in step 31 and the past data of the downstream stiffness read in step 32 are compared to determine whether the downstream stiffness has changed. Here, as a condition for determining that the downstream stiffness has changed, for example, the hydraulic pressure generated when a predetermined fluid amount is sent to the master cylinder 8 in the downstream stiffness comparison data and the downstream stiffness past data. When the difference in pressure (that is, the difference between the hydraulic pressure value of the comparison data with respect to the operation amount of the brake pedal 5 and the past data) is equal to or greater than a predetermined value, the downstream stiffness is changed and is smaller than the predetermined value. Determines that the downstream stiffness has not changed substantially.

  In other words, if “NO” is determined in the step 33, for example, a flag process is performed in which “no downstream stiffness change” is determined in the next step 34. Then, in the next step 35, the process returns. As a result, in the determination process in step 8 shown in FIG. 9, the determination result is set to “NO” in accordance with the flag process in step 34. As described above, if “NO” is determined in the process of step 8, the hydraulic characteristic storage data used at the time of the previous brake pedal operation is adopted as the hydraulic characteristic of downstream rigidity in step 9. Then, the control switching unit 56 selects the hydraulic pressure control, and implements the hydraulic pressure control immediately after the brake pedal operation is started.

  On the other hand, if “YES” is determined in step 33, the downstream stiffness comparison data read in step 31 is stored in the memory 26 </ b> A as downstream stiffness past data in the next step 36. The past downstream stiffness data stored in step 36 is read in step 32 of the next program cycle. Then, in the next step 37, for example, a flag process is performed in which “the downstream stiffness has changed”. That is, the determination result of step 8 is “YES”.

  If it is determined as “YES” in the process of step 8 (that is, the downstream stiffness has changed), the same process as that when “NO” is determined in step 2 is performed. As a result, when the downstream rigidity changes after the engine of the vehicle is started and the electric booster 16 is activated, the hydraulic pressure characteristic calculation data corresponding to the downstream rigidity is calculated again in the process of step 3. Become.

  The processing in step 36 is not performed until “YES” is determined in step 33. Therefore, the “downstream stiffness past data” read in step 32 is, for example, the hydraulic pressure of the downstream stiffness that serves as a reference as an initial value. Use characteristic data. Further, when the downstream stiffness past data is not stored when the processing of step 32 is performed, the downstream stiffness comparison data read in step 31 is used as the downstream stiffness past data, and the processing of step 8 is performed. It is also possible to save it in the memory 26A after the above process is completed.

  When the hydraulic pressure control is selected by the control switching unit 56 when the operation of the brake pedal is finished (that is, when the operation amount S becomes zero), the control switching unit 56 controls the piston position from the hydraulic pressure control. Switch to. Then, the motor control unit 57 controls the operation of the electric motor 21 so that the operation amount S becomes a piston position corresponding to zero. Further, when the hydraulic pressure control cannot be performed (for example, when the brake pedal 5 is largely depressed, the booster piston 18 first reaches the full stroke so that the amount of liquid necessary for realizing the target hydraulic pressure cannot be generated). In this case, the control switching unit 56 switches from hydraulic pressure control to piston position control.

  In such a case, since the hydraulic pressure characteristic data is no longer the data reflecting the actual downstream rigidity (the state of the wheel cylinders 3L, 3R, 4L, 4R), the calculation of the hydraulic pressure characteristic calculation data has not been performed. And Accordingly, when the brake pedal is operated next time, “NO” is determined in Step 2 of FIG. 9, and hydraulic pressure characteristic calculation data can be newly calculated in the next Step 3.

  Thus, in the present embodiment configured as described above, the first ECU 26 serving as the control means has the downstream stiffness (by the operation amount of the brake pedal 5, the motor position of the electric motor 21, and the brake fluid pressure by the fluid pressure sensor 29). There is a hydraulic pressure characteristic calculating means (for example, step 3 in FIG. 9) for calculating hydraulic pressure characteristic data with respect to the manipulated variable for realizing a brake characteristic according to the state of the wheel cylinder. When the brake pedal operation is performed after the hydraulic pressure characteristic data is calculated by the means, the electric motor 21 is operated according to the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data used during the previous brake pedal operation. It is set as the structure which performs control.

  Thus, by calculating the hydraulic pressure characteristic data according to the downstream rigidity at the time of brake pedal operation, it becomes possible to use the hydraulic pressure characteristic data at the previous brake pedal operation when the brake pedal is operated thereafter. The regenerative braking can be performed immediately after the start of the brake pedal operation, and the energy recovery rate by the regenerative cooperative control can be improved. Further, by using the hydraulic pressure characteristic data at the time of the previous brake pedal operation, the brake characteristic does not change every time the brake pedal operation is performed, so that the braking effect and the pedal feeling can be stabilized.

  On the other hand, if the downstream stiffness has changed during the current braking operation compared to the previous braking operation (that is, if the wheel cylinder state determining means determines that the state of the wheel cylinder has changed), the hydraulic pressure characteristic calculation data is newly set. The calculation is recalculated. Thereby, the rotation control of the electric motor 21 for moving the booster piston 18 forward and backward is optimized in order to secure the amount of liquid necessary for realizing the brake characteristics reflecting the change in the downstream stiffness with respect to the operation of the brake pedal. Therefore, it is possible to realize a brake characteristic with downstream rigidity.

  The first ECU 26 includes a memory 26A as a storage device for storing the hydraulic pressure characteristic calculation data, and the memory 26A is also after the vehicle engine is stopped (that is, the power supply to the first ECU 26 as the device is stopped). For example, the hydraulic pressure characteristic calculation data is stored as hydraulic pressure characteristic storage data. Therefore, the previously calculated hydraulic pressure characteristic calculation data is stored in the memory 26A of the ECU 26, and when the next hydraulic pressure characteristic data is calculated, the newly calculated hydraulic pressure characteristic calculation data and the previous hydraulic pressure characteristic calculation data are calculated. The hydraulic pressure characteristic data with the lower target hydraulic pressure value with respect to the operation amount of the brake pedal can be adopted.

  As a result, the hydraulic pressure characteristic data with a lower brake characteristic is adopted by the target hydraulic pressure calculation unit 55, and the hydraulic pressure control according to the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data is more secure. This can be performed on the side, and the possibility that the amount of liquid necessary for realizing the target hydraulic pressure cannot be generated from the master cylinder 8 can be reduced. Also, if the brake characteristics become excessively low, the hydraulic characteristic data is gradually corrected so that the hydraulic characteristic data becomes the data reflecting the change in the downstream stiffness, for example, by performing a large difference process in steps 10-13. can do.

  Further, the first ECU 26 calculates a difference between the hydraulic pressure characteristic calculation data calculated by the hydraulic pressure characteristic calculation means (for example, step 3 in FIG. 9) and the past hydraulic pressure characteristic calculation data as an absolute value. And a characteristic for storing a plurality of hydraulic pressure characteristic calculation data respectively calculated by the hydraulic pressure characteristic calculation means while it is determined that the absolute value of the difference calculated by the difference calculating means is larger than the threshold value. Calculation data storage means is provided. For this reason, when the absolute value of the difference becomes larger than a predetermined threshold value (in particular, the absolute value of the difference becomes larger than the threshold value continuously for a predetermined number of times, and the variation in the hydraulic pressure characteristic calculation data calculated during that time is predetermined. If it is within the range, for example, it can be determined that the downstream stiffness has changed significantly due to, for example, caliper replacement or air bleeding.

  In such a case, the newly calculated hydraulic pressure characteristic calculation data is adopted as the hydraulic pressure characteristic data for performing the hydraulic pressure control, so that the latest downstream rigidity can be obtained regardless of the past hydraulic pressure characteristic data. Therefore, when the hydraulic pressure control is performed, the electric motor 21 can be controlled in accordance with the target hydraulic pressure value corresponding to the downstream stiffness with respect to the operation amount, and the brake corresponding to the downstream stiffness. Characteristics can be realized.

  Therefore, according to the present embodiment, it is possible to suppress the deviation between the actual hydraulic pressure of the master cylinder 8 reflecting the downstream rigidity and the target hydraulic pressure, and the operation amount of the brake pedal 5 and the vehicle deceleration can be reduced. This relationship can be a substantially uniform stable characteristic relationship. As a result, brake characteristics corresponding to changes in the stiffness (downstream stiffness) of the hydraulic circuit due to variations in calipers constituting part of the wheel cylinders 3L, 3R, 4L, 4R, friction pad temperature, wear condition, deterioration, etc. Can be realized.

  In addition, by calculating the hydraulic pressure characteristic data according to the downstream stiffness at the time of brake pedal operation, the hydraulic pressure characteristic data at the previous brake pedal operation can be used while the downstream stiffness does not change at the subsequent brake pedal operation. Therefore, regenerative braking can be performed immediately after the start of the brake pedal operation, and the energy recovery rate by regenerative cooperative control can be improved. Thus, according to the present embodiment, it is possible to achieve both suppression of fluctuations in vehicle deceleration due to operation of the brake pedal and suppression of generation of hydraulic pressure by calculation processing of hydraulic pressure characteristic data.

  In the above embodiment, it is determined whether the hydraulic pressure characteristic calculation data has been calculated after starting the electric booster 16 in step 2 of FIG. 9, and the first brake pedal after starting the electric booster 16 is determined. The case where the configuration is such that the hydraulic pressure characteristic calculation data is calculated during operation has been described as an example. However, the present invention is not limited to this, and the processing in step 2 (calculation completion determining means) can be omitted. In this case, the processing in step 8 is performed after the reading processing in step 1. The hydraulic pressure characteristic calculation data may be calculated only when the downstream stiffness changes.

  Further, in the above embodiment, the case where the reference position and reference hydraulic pressure characteristic data by the characteristic lines 58 and 59 as shown in FIGS. 4 and 5 is used is described as an example. However, the present invention is not limited to this, and these characteristic data (i.e., reference characteristics) are determined based on the downstream rigidity of the reference determined in advance for each vehicle on which the electric booster is mounted. What is necessary is just to set it as individuality of a vehicle.

  Further, in the embodiment, the switching reference hydraulic pressure Pk is used as the hydraulic pressure for determining whether or not the brake hydraulic pressure is generated in the first and second hydraulic pressure chambers 11A and 11B of the master cylinder 8. The case of setting is described as an example. However, the present invention is not limited to this. For example, the switching reference hydraulic pressure Pk can be set to a predetermined hydraulic pressure other than this.

  As described above, according to the present embodiment, the control means includes a calculation completion determining means for determining whether or not the hydraulic pressure characteristic data is calculated by the hydraulic pressure characteristic calculating means when a brake pedal is operated. And when the brake pedal is operated after determining that the hydraulic pressure characteristic data has been calculated by the calculation completion determining means, the target fluid is calculated based on the hydraulic pressure characteristic data used at the previous brake pedal operation. The electric motor is controlled according to the pressure value. As a result, the hydraulic pressure characteristic data corresponding to the downstream stiffness is calculated at the time of the first brake pedal operation, and at the subsequent brake pedal operation, the hydraulic pressure characteristic data at the previous brake pedal operation is used. It is possible to achieve both suppression of fluctuations in vehicle deceleration with respect to operation and suppression of generation of hydraulic pressure by calculation processing of hydraulic pressure characteristic data. Further, regenerative braking can be performed immediately after the brake pedal operation is started, and the energy recovery rate by regenerative cooperative control can be improved. Further, by using the hydraulic pressure characteristic data at the time of the previous brake pedal operation, the brake characteristic does not change every time the brake pedal is operated, and the braking effect and the pedal feeling are stabilized.

  Further, the hydraulic pressure characteristic calculation unit performs the calculation of the hydraulic pressure characteristic data a plurality of times, and among the newly calculated hydraulic pressure characteristic calculation data and the past hydraulic pressure characteristic calculation data, the target hydraulic pressure with respect to the operation amount. The hydraulic pressure characteristic data having a lower value is employed. In this way, for example, by using the one having a lower brake characteristic among a plurality of hydraulic pressure characteristic data stored in the storage device, it is possible to realize the amount of fluid necessary to realize the brake characteristic due to the change in downstream rigidity. The possibility of disappearing can be reduced.

  The control means includes wheel cylinder state change determination means for determining whether or not the state of the wheel cylinder has changed since the previous calculation of the hydraulic pressure characteristic calculation data by the hydraulic pressure characteristic calculation means, When it is determined by the wheel cylinder state change determining means that the state of the wheel cylinder is changing, the hydraulic pressure characteristic calculating data is calculated by the hydraulic pressure characteristic calculating means at the next brake pedal operation. As a result, when the state of the wheel cylinder (downstream rigidity) changes, the brake characteristic similar to the downstream rigidity can be realized by recalculating the hydraulic pressure characteristic data.

  The control means includes difference calculation means for calculating a difference between the hydraulic pressure characteristic calculation data calculated by the hydraulic pressure characteristic calculation means and past hydraulic pressure characteristic storage data as an absolute value, and is calculated by the difference calculation means. When the absolute value of the difference is larger than a predetermined threshold value, the hydraulic pressure characteristic value used at the previous operation of the brake pedal is employed. In addition, while the control means determines that the absolute value of the difference calculated by the difference calculation means is continuously larger than the threshold value by a predetermined number of times, the hydraulic pressure characteristic calculation means Characteristic calculation data storage means for storing a plurality of calculated hydraulic pressure characteristic calculation data, respectively, wherein the absolute value of the difference by the difference calculation means is determined to be continuously greater than the threshold by a predetermined number of times, and When the variation of the hydraulic pressure characteristic calculation data stored by the characteristic calculation data storage means is within a predetermined range, the hydraulic pressure characteristic calculation data stored by the characteristic calculation data storage means is used as the hydraulic pressure characteristic. The configuration is adopted as data. As a result, when the absolute value of the difference becomes larger than a predetermined threshold value (in particular, the absolute value of the difference becomes larger than the threshold value continuously for a predetermined number of times, and the variation in the hydraulic pressure characteristic calculation data calculated during that time is predetermined. If it is within the range, for example, it can be determined that the downstream stiffness has changed significantly due to caliper replacement or air bleeding, and the latest downstream stiffness can be determined regardless of past hydraulic characteristics data. The reflected hydraulic pressure characteristic data can be obtained.

1L, 1R front wheel (wheel)
2L, 2R Rear wheel (wheel)
3L, 3R, 4, 4L, 4R Wheel cylinder 5 Brake pedal 7 Operation amount detector (operation amount detection means)
8 Master cylinder 9 Cylinder body 11A, 11B Hydraulic chamber 14 Reservoir (hydraulic fluid tank)
16 Electric Booster 17 Booster Housing 18 Booster Piston (P Piston)
19 Input rod (input member)
20 electric actuator 21 electric motor 21A rotation sensor (motor position detecting means)
23 Deceleration mechanism 24 Linear motion mechanism 26 First ECU (control means)
26A memory (storage device)
27 Signal line 28 Vehicle data bus 29 Hydraulic pressure sensor (hydraulic pressure detecting means)
30 Hydraulic supply system (ESC)
32 second ECU
51 Regenerative cooperative control device (regenerative braking control means)
52 power line 53 target piston position calculation unit (target piston position calculation means)
54 Target hydraulic pressure characteristic calculation unit (target hydraulic pressure characteristic calculation means)
55 Target hydraulic pressure calculation unit (target hydraulic pressure calculation means)
56 Control switching part (control switching means)
57 Motor controller (motor control means)
58 Characteristic line (reference position characteristic)
59 Characteristic line (reference hydraulic pressure characteristic)
60 characteristic line (offset target hydraulic pressure characteristic)
61, 62 Characteristic line (hydraulic pressure characteristic data)
Pk switching reference hydraulic pressure

Claims (4)

An operation amount detection means for detecting an operation amount of the brake pedal;
An electric motor that generates a brake fluid pressure by moving a piston of a master cylinder connected to a wheel cylinder;
Motor position detecting means for detecting a motor position of the electric motor;
Hydraulic pressure detecting means for detecting the brake hydraulic pressure generated by driving the electric motor;
Control means for controlling the electric motor according to the amount of operation of the brake pedal,
The control means includes
Hydraulic pressure characteristic calculating means for calculating hydraulic pressure characteristic data with respect to the manipulated variable for realizing a brake characteristic corresponding to a state of the wheel cylinder by the manipulated variable, the motor position and the brake hydraulic pressure;
At the time of brake pedal operation after the hydraulic pressure characteristic data is calculated by the hydraulic pressure characteristic calculator, the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data used at the time of the previous brake pedal operation is used. A brake control device that controls an electric motor. The control means includes
A calculation completion determination unit that determines whether or not the hydraulic pressure characteristic data is calculated by the hydraulic pressure characteristic calculation unit when the brake pedal is operated;
At the time of brake pedal operation after determining that the hydraulic pressure characteristic data has been calculated by the calculation completion determination means, the target hydraulic pressure value calculated based on the hydraulic pressure characteristic data used at the previous brake pedal operation is set. The brake control device according to claim 1, wherein the electric motor is controlled accordingly.   The hydraulic pressure characteristic calculation means calculates the hydraulic pressure characteristic data a plurality of times, and among the newly calculated hydraulic pressure characteristic calculation data and past hydraulic pressure characteristic calculation data, the target hydraulic pressure value relative to the manipulated variable is The brake control device according to claim 1, wherein the lower hydraulic pressure characteristic data is employed. The control means includes
Wheel cylinder state change determination means for determining whether or not the state of the wheel cylinder has changed since the previous calculation of the hydraulic pressure characteristic calculation data by the hydraulic pressure characteristic calculation means,
When the wheel cylinder state change determining means determines that the state of the wheel cylinder has changed, the hydraulic pressure characteristic calculating means calculates the hydraulic pressure characteristic calculation data at the next brake pedal operation. The brake control device according to claim 3.

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