JP2018088735A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device capable of keeping a vehicle behavior stable when a vehicle skids by regenerative braking.SOLUTION: A first ECU 27 includes regenerative slip control means that repeatedly executes slip suppression control to decrease a regenerative braking amount of a motor generator 55 by a predetermined amount and then keep the regenerative braking amount for a predetermined time while it is detected that front wheels 2L and 2R are skidding based on a detection value of a slip amount detector 56 during the regenerative braking by the motor generator 55. The regenerative slip control means sets the predetermined decrease amount for the regenerative braking when it is detected that the front wheels 2L and 2R are skidding to be larger than the predetermined decrease amount for the regenerative braking in the subsequent slip suppression control, and to be changed according to a turning amount of the front wheels 2L and 2R detected by a turning amount detector 57.SELECTED DRAWING: Figure 1

Description

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

  Controls the distribution of friction braking force by friction lining and regenerative braking force by regenerative motor in vehicles equipped with regenerative motors (motor / generator, generator motor) for driving (drive) such as electric cars and hybrid cars In addition, it is configured to obtain a desired braking force in the entire vehicle (see, for example, Patent Document 1).

JP2015-146657A

  In the prior art disclosed in Patent Document 1, slip is detected from the vehicle body speed and the wheel speed of the driving wheel, and when a slip occurs, a preset regenerative braking amount is reduced. In this case, if slip occurs during straight braking, the preset regenerative braking amount is reduced. However, when slip occurs during turning braking, for example, when slip occurs during straight braking, the convergence of the slip is delayed by the amount of lateral force generated during turning braking, and the vehicle behavior becomes unstable and the braking distance increases. There is a risk of doing.

  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 provide a brake control device that can quickly converge a slip during turning.

  In order to solve the above-described problems, the present invention controls a regenerative braking amount of a regenerative motor provided in a vehicle, and controls a friction braking device having a friction member that is provided on each wheel and moves by receiving hydraulic pressure. A brake control device that brakes the vehicle by means of slip amount detection means for detecting the slip amount of the wheel, and a detected value of the slip amount detection means exceeds a slip threshold during regenerative braking by the regenerative motor. Regenerative slip control means for determining that the wheel is slipping, reducing the regenerative braking amount by a predetermined amount, and repeatedly performing slip suppression control for holding the reduced regenerative braking amount for a predetermined time; And the regenerative slip control means holds a predetermined decrease amount of the first regenerative braking when it is detected that the wheel is slipping. Larger than the predetermined reduction amount of the second regenerative braking in the slip suppression control during elapsed between, and is characterized in that setting is varied depending on the turning amount of the vehicle.

  According to the present invention, the amount of decrease in regenerative braking increases according to the turning amount, so that the slip can be converged quickly, the vehicle behavior can be kept stable, and the braking distance can be shortened.

1 is a conceptual diagram of a vehicle equipped with a brake control device according to a first embodiment. It is a block diagram which shows the electric booster, the hydraulic pressure supply apparatus, etc. in FIG. It is explanatory drawing which shows the braking force and the grip limit which are applied to a drive wheel at the time of straight braking and turning braking. It is a flowchart which shows the control processing by a brake control apparatus. It is a characteristic diagram which shows an example of the decreasing amount of the regenerative braking amount with respect to turning amount. It is a characteristic diagram which shows an example of the time change of the driving wheel regenerative braking amount and driving wheel slip amount by 1st Embodiment. It is a characteristic diagram which shows an example of the time change of the driving wheel regenerative braking amount and the driving wheel slip amount when the holding time of the regenerative braking amount according to the second embodiment is variable.

  Hereinafter, a brake control device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the brake control device is applied to a four-wheeled vehicle equipped with a regenerative motor (motor / generator) such as an electric vehicle or a hybrid vehicle. To do.

  1 to 6 show a first embodiment of the present invention. In FIG. 1, for example, left and right front wheels 2L and 2R and left and right rear wheels 3L and 3R are provided on the lower side (road surface side) of a vehicle body 1 constituting a vehicle body. The left and right front wheels 2L and 2R are respectively provided with front wheel side wheel cylinders 4L and 4R, and the left and right rear wheels 3L and 3R are respectively provided with rear wheel side wheel cylinders 5L and 5R.

  These wheel cylinders 4L, 4R, 5L, 5R constitute hydraulic disc brake or drum brake cylinders and apply braking force to the respective wheels (front wheels 2L, 2R and rear wheels 3L, 3R). It is. That is, the wheel cylinders 4L, 4R, 5L, and 5R constitute a friction braking device 6 (for example, a disc brake and a drum brake) together with a friction lining (a friction pad or a brake shoe) that moves by receiving hydraulic pressure. The friction braking device 6 is provided on each wheel 2L, 2R, 3L, 3R, and is a rotating member (disk or drum) that rotates a friction lining together with the wheels 2L, 2R, 3L, 3R by the wheel cylinders 4L, 4R, 5L, 5R. The vehicle can be braked by the friction between the friction lining and the rotating member.

  A brake pedal 7 is provided on the front board side of the vehicle body 1. The brake pedal 7 is depressed by a driver (driver) in the direction of arrow A in FIGS. The brake pedal 7 is provided with a brake switch 7A and an operation amount detection sensor 8. The brake switch 7A detects the presence or absence of a brake operation of the vehicle, and turns on and off a brake lamp (not shown), for example. is there. Further, the operation amount detection sensor 8 detects a depression operation amount (stroke amount) or a depression force of the brake pedal 7 and outputs a detection signal to ECUs 27 and 35, a vehicle data bus 29, and the like which will be described later. When the brake pedal 7 is depressed, brake fluid pressure is generated in the master cylinder 9 via an electric booster 17 described later.

  As shown in FIG. 2, the master cylinder 9 has a bottomed cylindrical cylinder body 10 that is closed with one side being an open end and the other side being a bottom. The cylinder body 10 is provided with first and second supply ports 10A and 10B communicating with a reservoir 15 described later, and the first supply port 10A is first driven by a sliding displacement of a booster piston 19 described later. The fluid pressure chamber 12A is communicated and blocked. On the other hand, the second supply port 10B is communicated with or blocked from the second hydraulic chamber 12B by a second piston 11 described later.

  The cylinder main body 10 is detachably fixed to a booster housing 18 of an electric booster 17 to be described later using a plurality of mounting bolts (not shown) or the like. The master cylinder 9 includes a cylinder body 10, a first piston (a booster piston 19 and an input rod 20 described later) and a second piston 11, a first hydraulic chamber 12A, and a second hydraulic chamber 12B. The first return spring 13 and the second return spring 14 are included. Here, in FIG. 2, the signal line of the electric circuit is shown by a thin line with two diagonal lines in the middle, and the power line of the electric circuit is shown by a thick line with two diagonal lines in the middle. The hydraulic piping is shown by a thin line without two diagonal lines in the middle.

  In this case, in the master cylinder 9, the first piston is constituted by a booster piston 19 and an input rod 20, which will be described later, and the first hydraulic chamber 12A formed in the cylinder body 10 is the second piston 11. And the booster piston 19 (and the input rod 20). The second hydraulic chamber 12 </ b> B is defined in the cylinder body 10 between the bottom of the cylinder body 10 and the second piston 11.

  The first return spring 13 is located between the booster piston 19 and the second piston 11 in the first hydraulic chamber 12 </ b> A, and the booster piston 19 faces the opening end side of the cylinder body 10. Is energized. The second return spring 14 is located in the second hydraulic pressure chamber 12B and is disposed between the bottom portion of the cylinder body 10 and the second piston 11, and the second piston 11 is connected to the first hydraulic pressure. Energizing toward the chamber 12A side.

  In the cylinder body 10 of the master cylinder 9, the booster piston 19 (input rod 20) and the second piston 11 are displaced toward the bottom of the cylinder body 10 in response to the depression operation of the brake pedal 7. When the supply ports 10A and 10B are shut off, the brake fluid pressure is generated by the brake fluid in the first and second fluid pressure chambers 12A and 12B. On the other hand, when the operation of the brake pedal 7 is released, the booster piston 19 (and the input rod 20) and the second piston 11 are brought into the opening of the cylinder body 10 by the first and second return springs 13 and 14. When moving in the direction indicated by the arrow B, the hydraulic pressure in the first and second hydraulic pressure chambers 12A and 12B is released while receiving the brake fluid supplied from the reservoir 15.

  The cylinder body 10 of the master cylinder 9 is provided with a reservoir 15 as a hydraulic fluid tank in which brake fluid is stored. The reservoir 15 supplies brake fluid to the hydraulic chambers 12A and 12B in the cylinder body 10. Supply and discharge. That is, while the first supply port 10A is connected to the first hydraulic chamber 12A by the booster piston 19, and the second supply port 10B is connected to the second hydraulic chamber 12B by the second piston 11. The brake fluid in the reservoir 15 is supplied and discharged into the hydraulic chambers 12A and 12B.

  On the other hand, when the first supply port 10A is blocked from the first hydraulic chamber 12A by the booster piston 19 and the second supply port 10B is blocked from the second hydraulic chamber 12B by the second piston 11. The supply and discharge of the brake fluid in the reservoir 15 with respect to the hydraulic chambers 12A and 12B is cut off. For this reason, brake fluid pressure is generated in the first and second fluid pressure chambers 12A, 12B of the master cylinder 9 along with the brake operation, and this brake fluid pressure is, for example, a pair of cylinder side fluid pressure pipes 16A. , 16B to the hydraulic pressure supply device 33 (that is, ESC 33) described later.

  Between the brake pedal 7 and the master cylinder 9 of the vehicle, there is provided an electric booster 17 as a booster that increases the operating force of the brake pedal 7 or as a brake device. The electric booster 17 variably controls the brake hydraulic pressure generated in the master cylinder 9 by drivingly controlling an electric actuator 21 (an electric motor 22 thereof) described later based on the output of the operation amount detection sensor 8. To do.

  The electric booster 17 is provided with a booster housing 18 fixed to the front wall of the passenger compartment, which is a front board of the vehicle body, and is movably provided in the booster housing 18 and is movable relative to an input rod 20 described later. A booster piston 19 as a piston and an electric actuator 21 (described later) as an actuator for moving the booster piston 19 forward and backward in the axial direction of the master cylinder 9 and applying a booster thrust to the booster piston 19 are configured.

  The booster piston 19 is configured by a cylindrical member that is slidably inserted in the cylinder body 10 of the master cylinder 9 from the opening end side in the axial direction. On the inner peripheral side of the booster piston 19, an input rod (input member) that is pushed directly in accordance with the operation of the brake pedal 7 and moves forward and backward in the axial direction of the master cylinder 9 (that is, the arrow A and B directions). An input piston) 20 is slidably inserted. The input rod 20 constitutes the first piston of the master cylinder 9 together with the booster piston 19, and the brake pedal 7 is connected to the rear side (one side) end of the input rod 20. In the cylinder body 10, a first hydraulic chamber 12 </ b> A is defined between the second piston 11, the booster piston 19, and the input rod 20.

  The booster housing 18 is provided between a cylindrical speed reducer case 18A that houses a speed reduction mechanism 24 and the like to be described later, and the speed reducer case 18A and the cylinder body 10 of the master cylinder 9, and the booster piston 19 is disposed in the axial direction. A cylindrical support case 18B supported so as to be slidably displaceable and a support case 18B across the reduction gear case 18A are arranged on the opposite side (one axial direction) of the reduction gear case 18A. And a stepped cylindrical lid 18C that closes the opening on the side. A support plate 18D for fixedly supporting an electric motor 22 described later is provided on the outer peripheral side of the speed reducer case 18A.

  The input rod 20 is inserted into the booster housing 18 from the lid 18C side and extends in the booster piston 19 in the axial direction toward the first hydraulic chamber 12A. Between the booster piston 19 and the input rod 20, a pair of neutral springs 20A and 20B are interposed. The booster piston 19 and the input rod 20 are elastically held at a neutral position by the spring force of the neutral springs 20A and 20B, and the spring force of the neutral springs 20A and 20B 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 20 receives the hydraulic pressure generated in the first hydraulic pressure chamber 12 </ b> A during a brake operation as a brake reaction force, and the input rod 20 transmits this to the brake pedal 7. To do. Thereby, an appropriate treading response is given to the driver of the vehicle via the brake pedal 7, and a good pedal feeling (effectiveness of the brake) can be obtained. As a result, the operational feeling of the brake pedal 7 can be improved, and the pedal feeling (stepping response) can be kept good. Further, the input rod 20 has a structure capable of abutting on the booster piston 19 and advancing the booster piston 19 when the input rod 20 advances a predetermined amount with respect to the booster piston 19. With this structure, when the electric actuator 21 and the first ECU 27 described later fail, the booster piston 19 can be advanced by the depression force applied to the brake pedal 7 to generate hydraulic pressure in the master cylinder 9. Yes.

  The electric actuator 21 of the electric booster 17 includes an electric motor 22 provided on a reduction gear case 18A of the booster housing 18 via a support plate 18D, and the rotation of the electric motor 22 is reduced to reduce the rotation inside the reduction gear case 18A. A speed reduction mechanism 24 such as a belt for transmitting to the cylindrical rotating body 23 and a linear motion mechanism 25 such as a ball screw for converting the rotation of the cylindrical rotating body 23 into the axial displacement (advance and retreat movement) of the booster piston 19 are configured. . The booster piston 19 and the input rod 20 have their front end portions (end portions on the other side in the axial direction) facing the first hydraulic chamber 12A of the master cylinder 9, and pedal force (thrust force) transmitted from the brake pedal 7 to the input rod 20 ) And the booster thrust transmitted from the electric actuator 21 to the booster piston 19, the brake fluid pressure is generated in the master cylinder 9.

  In other words, the booster piston 19 of the electric booster 17 is driven by the electric actuator 21 based on the output (ie, control command) of the operation amount detection sensor 8, and brake fluid pressure (master cylinder pressure) is applied to the master cylinder 9. The pump mechanism to generate is comprised. Further, in the support case 18B of the booster housing 18, there is provided a return spring 26 that constantly urges the booster piston 19 in the braking release direction (the arrow B direction in FIGS. 1 and 2). The booster piston 19 is configured such that when the brake operation is released, the electric motor 22 is rotated in the reverse direction and is returned to the initial position shown in FIG. 2 by the urging force of the return spring 26.

  The electric motor 22 is configured using, for example, a DC brushless motor, and the electric motor 22 is provided with a rotation sensor 22A called a resolver and a current sensor (not shown) that detects a motor current. The rotation sensor 22A detects the rotation position (rotation angle) of the electric motor 22 (motor shaft) and outputs the detection signal to a control unit (hereinafter referred to as a first ECU 27) that is a first control circuit. The first ECU 27 performs feedback control based on this rotational position signal. The rotation sensor 22A has a function as a rotation detection unit that detects the absolute displacement of the booster piston 19 relative to the vehicle body based on the detected rotation position of the electric motor 22.

  Further, the rotation sensor 22A, together with the operation amount detection sensor 8, constitutes a displacement detection means for detecting the relative displacement amount between the booster piston 19 and the input rod 20, and these detection signals are sent to the first ECU 27. . The rotation detection means is not limited to the rotation sensor 22A such as a resolver, but may be a rotation type potentiometer capable of detecting absolute displacement (angle). The speed reduction mechanism 24 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 25 that changes the rotational motion into a linear motion can be constituted by, for example, a rack and pinion mechanism. Further, the speed reduction mechanism 24 is not necessarily provided. For example, the motor shaft is integrally provided on the cylindrical rotating body 23, the stator of the electric motor is arranged around the cylindrical rotating body 23, and directly by the electric motor. The cylindrical rotating body 23 may be rotated.

  The first ECU 27 is composed of, for example, a microcomputer and constitutes a part of the electric booster 17. The first ECU 27 serves as a control means (friction braking control means) for controlling the friction braking device 6 together with a second ECU 35 described later. Specifically, the first ECU 27 constitutes a first control circuit (electric booster controller) that electrically drives and controls the electric actuator 21 (electric motor 22) of the electric booster 17. .

  The input side of the first ECU 27 includes a brake switch 7A that detects whether or not the brake pedal 7 is operated, an operation amount detection sensor 8 that detects an operation amount or pedaling force of the brake pedal 7, a rotation sensor 22A of the electric motor 22, and An in-vehicle signal line 28 capable of communication called L-CAN, for example, the current sensor, a vehicle data bus 29 for exchanging signals from an ECU (for example, a third ECU 54 described later) of another vehicle device, and the like It is connected to the. The vehicle data bus 29 is a serial communication unit called V-CAN mounted on the vehicle, and performs multiplex communication for in-vehicle use. Further, the first ECU 27 is connected to the power supply line 30, and power from the battery 31 (see FIG. 1) is supplied through the power supply line 30.

  The hydraulic pressure sensor 32 as a hydraulic pressure detecting means for detecting the brake hydraulic pressure of the master cylinder 9 detects, for example, the hydraulic pressure in the cylinder side hydraulic pipe 16A. The master side is connected to the cylinder side hydraulic pipe 16A. The brake fluid pressure supplied to the later-described ESC 33 is detected. In the present embodiment, the hydraulic pressure sensor 32 is electrically connected to a second ECU 35 to be described later, and a detection signal from the hydraulic pressure sensor 32 is transmitted from the second ECU 35 via the signal line 28 to the first ECU 35. Also sent to the ECU 27 by communication. The hydraulic pressure sensor 32 may be directly attached to the master cylinder 9 as long as the brake hydraulic pressure of the master cylinder 9 can be detected, and the detection signal is directly transmitted without going through the second ECU 35. It may be configured to be input to one ECU 27.

  The output side of the first ECU 27 is connected to the electric motor 22, the in-vehicle signal line 28, the vehicle data bus 29, and the like. The first ECU 27 variably controls the brake hydraulic pressure generated in the master cylinder 9 by the electric actuator 21 in accordance with detection signals from the operation amount detection sensor 8 and the hydraulic pressure sensor 32, and the electric booster 17 It also has a function of determining whether or not is operating normally.

  Here, in the electric booster 17, when the brake pedal 7 is depressed, the input rod 20 moves forward into the cylinder body 10 of the master cylinder 9, and the movement at this time is detected by the operation amount detection sensor 8. Detected. The first ECU 27 outputs a start command to the electric motor 22 by a detection signal from the operation amount detection sensor 8 to rotationally drive the electric motor 22, and the rotation is transmitted to the cylindrical rotating body 23 via the speed reduction mechanism 24. At the same time, the rotation of the cylindrical rotating body 23 is converted into the axial displacement of the booster piston 19 by the linear motion mechanism 25.

  At this time, the booster piston 19 moves forward integrally with the input rod 20 toward the cylinder body 10 of the master cylinder 9, and the stepping force (thrust) applied from the brake pedal 7 to the input rod 20 and the electric actuator 21 increase the booster. Brake hydraulic pressure corresponding to the booster thrust applied to the piston 19 is generated in the first and second hydraulic pressure chambers 12A and 12B of the master cylinder 9. Further, when the braking force of the entire vehicle is distributed between the friction braking force by the friction lining of the friction braking device 6 and the regenerative braking force by the motor generator 55 (see FIG. 1) described later, that is, the friction braking force (friction When the braking force of the entire vehicle is obtained by the braking force of both the braking and the regenerative braking force (regenerative braking), the booster piston 19 is driven by the electric actuator 21 so that the brake fluid pressure is reduced by the amount corresponding to the regenerative braking force. Is displaced.

  The first ECU 27 can monitor the hydraulic pressure generated in the master cylinder 9 by receiving the detection signal from the hydraulic pressure sensor 32 from the signal line 28, and the electric booster 17 operates normally. It can be determined whether or not.

  Next, a hydraulic pressure supply device 33 provided between the wheel cylinders 4L, 4R, 5L, 5R and the master cylinder 9 disposed on each wheel (front wheels 2L, 2R and rear wheels 3L, 3R) side of the vehicle. (That is, ESC 33) will be described.

  The ESC 33 variably controls the brake hydraulic pressure generated in the master cylinder 9 (first and second hydraulic pressure chambers 12A and 12B) by the electric booster 17 as the wheel cylinder pressure for each wheel ( A wheel cylinder pressure control device is individually supplied to the wheel cylinders 4L, 4R, 5L, and 5R of the front wheels 2L and 2R and the rear wheels 3L and 3R.

  That is, the ESC 33 performs various types of brake control (for example, braking force distribution control for distributing braking force to the front wheels 2L and 2R, the rear wheels 3L and 3R, antilock brake control, vehicle stabilization control, etc.). The necessary brake fluid pressure is supplied from the master cylinder 9 to the wheel cylinders 4L, 4R, 5L, 5R via the cylinder side fluid pressure pipes 16A, 16B and the like.

  Here, the ESC 33 supplies the hydraulic pressure output from the master cylinder 9 (first and second hydraulic pressure chambers 12A, 12B) via the cylinder side hydraulic pipes 16A, 16B to the brake side pipe parts 34A, 34B, Distribution and supply to the wheel cylinders 4L, 4R, 5L, and 5R via 34C and 34D. As a result, independent braking forces are individually applied to the wheels (front wheels 2L, 2R, rear wheels 3L, 3R) as described above. The ESC 33 is an electric motor that drives control valves 40, 40 ', 41, 41', 42, 42 ', 45, 45', 46, 46 ', 53, 53' and hydraulic pumps 47, 47 ', which will be described later. The motor 48 is configured to include hydraulic pressure control reservoirs 52 and 52 '.

  The second ECU 35 is composed of a microcomputer, for example, and constitutes a part of the ESC 33. The second ECU 35, together with the first ECU 27, serves as control means (friction braking control means) for controlling the friction braking device 6. Specifically, the second ECU 35 constitutes a second control circuit (hydraulic pressure supply controller) that electrically drives and controls the ESC 33. The input side of the second ECU 35 is connected to the hydraulic pressure sensor 32, the signal line 28, the vehicle data bus 29, a slip amount detector 56 described later, and the like. The output side of the second ECU 35 includes control valves 40, 40 ', 41, 41', 42, 42 ', 45, 45', 46, 46 ', 53, 53', an electric motor 48, a signal line, which will be described later. 28, the vehicle data bus 29 and the like. Further, the second ECU 35 is connected to the power supply line 30, and power from the battery 31 (see FIG. 1) is supplied through the power supply line 30.

  Here, the second ECU 35 includes the control valves 40, 40 ', 41, 41', 42, 42 ', 45, 45', 46, 46 ', 53, 53', the electric motor 48, etc. of the ESC 33, which will be described later. In this way, the drive is controlled individually. As a result, the second ECU 35 controls the wheel cylinders 4L, 4R to reduce, hold, increase or pressurize the brake fluid pressure supplied to the wheel cylinders 4L, 4R, 5L, 5R from the brake side piping parts 34A to 34D. This is performed separately for each of 5L and 5R.

  In other words, the second ECU 35 controls the ESC 33 so as to appropriately distribute the braking force to each wheel (the front wheels 2L, 2R and the rear wheels 3L, 3R) according to the ground load or the like when the vehicle is braked. Power distribution control, anti-lock brake control that automatically adjusts the braking force of the wheels 2L, 2R, 3L, 3R during braking to prevent the wheels 2L, 2R, 3L, 3R from being locked, and the running wheels 2L, 2R , 3L, 3R is detected, and the brake force applied to each wheel 2L, 2R, 3L, 3R is automatically controlled appropriately regardless of the amount of operation of the brake pedal 7, and understeer and oversteer are suppressed. Vehicle stabilization control that stabilizes the behavior of the vehicle, slope start assist control that assists start by maintaining the braking state on a slope (particularly uphill), and wheel slipping prevention during start Control control, vehicle follow-up control for maintaining a certain distance from the preceding vehicle, lane departure avoidance control for maintaining the driving lane, obstacle avoidance control for avoiding collision with obstacles ahead or behind the vehicle, etc. be able to.

  The ESC 33 is connected to one output port of the master cylinder 9 (i.e., the cylinder side hydraulic pipe 16A), and supplies fluid to the wheel cylinder 4L on the left front wheel (FL) side and the wheel cylinder 5R on the right rear wheel (RR) side. The first hydraulic system 36 for supplying pressure, and the wheel cylinder 4R on the right front wheel (FR) side and the wheel on the left rear wheel (RL) side are connected to the other output port (that is, the cylinder side hydraulic pipe 16B). There are two systems of hydraulic circuits including a second hydraulic system 36 'for supplying hydraulic pressure to the cylinder 5L. Here, since the first hydraulic system 36 and the second hydraulic system 36 ′ have the same configuration, the following description is given only for the first hydraulic system 36, and the second hydraulic system 36. With respect to ′, “′” is attached to the reference numerals of the respective components, and the description thereof is omitted.

  The first hydraulic system 36 of the ESC 33 has a brake pipe 37 connected to the tip side of the cylinder side hydraulic pipe 16A. The brake pipe 37 includes a first pipe section 38 and a second pipe section 39. These two branches are connected to the wheel cylinders 4L and 5R, respectively. The brake pipe line 37 and the first pipe line part 38 constitute a pipe line that supplies the hydraulic pressure to the wheel cylinder 4L together with the brake side pipe part 34A, and the brake pipe line 37 and the second pipe line part 39 constitute the brake side pipe. A pipe 34 that supplies hydraulic pressure to the wheel cylinder 5R is configured together with the portion 34D.

  The brake pipe 37 is provided with a brake hydraulic pressure supply control valve 40, and the supply control valve 40 is a normally open electromagnetic switching valve that opens and closes the brake pipe 37. The first pipe section 38 is provided with a pressure increase control valve 41, and the pressure increase control valve 41 is constituted by a normally open electromagnetic switching valve that opens and closes the first pipe section 38. The second pipe section 39 is provided with a pressure increase control valve 42, and the pressure increase control valve 42 is a normally open electromagnetic switching valve that opens and closes the second pipe section 39.

  On the other hand, the first hydraulic system 36 of the ESC 33 has first and second decompression lines 43 and 44 that connect the wheel cylinders 4L and 5R and the hydraulic pressure control reservoir 52, respectively. The passages 43 and 44 are provided with first and second pressure reduction control valves 45 and 46, respectively. The first and second pressure reduction control valves 45 and 46 are normally closed electromagnetic switching valves that open and close the pressure reduction lines 43 and 44, respectively.

  Further, the ESC 33 includes a hydraulic pump 47 as a hydraulic pressure generating means that is a hydraulic pressure source, and the hydraulic pump 47 is rotationally driven by an electric motor 48. Here, the electric motor 48 is driven by the power supply from the second ECU 35, and the rotation is stopped together with the hydraulic pump 47 to stop the power supply. The discharge side of the hydraulic pump 47 is positioned downstream of the supply control valve 40 in the brake line 37 via the check valve 49 (that is, the first line part 38 and the second line part 39). Is connected to the position where the The suction side of the hydraulic pump 47 is connected to a hydraulic pressure control reservoir 52 via check valves 50 and 51.

  The hydraulic pressure control reservoir 52 is provided to temporarily store surplus brake fluid, and is not limited to the antilock brake control of the brake system (ESC 33), and the wheel cylinders 4L and 5R are not limited to other brake controls. Excess brake fluid flowing out from a cylinder chamber (not shown) is temporarily stored. The suction side of the hydraulic pump 47 is connected to the cylinder side hydraulic pipe 16A (that is, the brake line 37 of the master cylinder 9) via a check valve 50 and a pressurization control valve 53 that is a normally closed electromagnetic switching valve. Of these, it is connected to the upstream side of the supply control valve 40.

  Electric motors for driving the control valves 40, 40 ', 41, 41', 42, 42 ', 45, 45', 46, 46 ', 53, 53' and the hydraulic pumps 47, 47 'constituting the ESC 33. The motor 48 is controlled in accordance with a predetermined procedure in accordance with a control signal output from the second ECU 35.

  That is, the first hydraulic system 36 of the ESC 33 uses the brake line 37 and the first and second hydraulic pressures generated by the electric booster 17 in the master cylinder 9 during normal operation by the driver's brake operation. It is directly supplied to the wheel cylinders 4L and 5R via the pipe sections 38 and 39. For example, when anti-lock brake control or the like is executed, the pressure increase control valves 41 and 42 are closed to hold the hydraulic pressures of the wheel cylinders 4L and 5R, and the pressure reduction control is performed when the hydraulic pressures of the wheel cylinders 4L and 5R are reduced. The valves 45 and 46 are opened, and the hydraulic pressure in the wheel cylinders 4L and 5R is discharged so as to escape to the hydraulic pressure control reservoir 52.

  Further, when the hydraulic pressure supplied to the wheel cylinders 4L and 5R is increased in order to perform stabilization control (side slip prevention control) when the vehicle is running, the hydraulic pressure is controlled by the electric motor 48 with the supply control valve 40 closed. The pump 47 is operated, and the brake fluid discharged from the hydraulic pump 47 is supplied to the wheel cylinders 4L and 5R via the first and second pipe sections 38 and 39. At this time, since the pressurization control valve 53 is opened, the brake fluid in the reservoir 15 is supplied from the master cylinder 9 side to the suction side of the hydraulic pump 47.

  As described above, the second ECU 35 determines the supply control valve 40, the pressure increase control valves 41, 42, the pressure reduction control valves 45, 46, the pressure control valve 53, and the electric motor 48 (that is, the liquid) based on the vehicle operation information and the like. The operation of the pressure pump 47) is controlled, and the hydraulic pressure supplied to the wheel cylinders 4L and 5R is appropriately maintained, or reduced or increased. As a result, brake control such as the braking force distribution control, vehicle stabilization control, brake assist control, antilock brake 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 48 (that is, the hydraulic pump 47) stopped, the supply control valve 40 and the pressure increase control valves 41 and 42 are opened, and the pressure reduction control valves 45 and 46 and the pressure control valves 45 and 46 are increased. The pressure control valve 53 is closed. In this state, the first piston (that is, the booster piston 19 and the input rod 20) and the second piston 11 of the master cylinder 9 are displaced in the axial direction in the cylinder body 10 in response to the depression operation of the brake pedal 7. Sometimes, the brake fluid pressure generated in the first and second fluid pressure chambers 12A and 12B is transferred from the cylinder side fluid pressure piping 16A side through the first fluid pressure system 36 and the brake side piping portions 34A and 34D of the ESC 33. To the wheel cylinders 4L and 5R. The brake fluid pressure generated in the second fluid pressure chamber 12B is supplied from the cylinder side fluid pressure pipe 16B side to the wheel cylinders 4R and 5L via the second fluid pressure system 36 'and the brake side pipe portions 34B and 34C. The

  When the booster piston 19 cannot be operated by the electric motor 22 due to the failure of the electric booster 17, the brake hydraulic pressure generated in the first and second hydraulic pressure chambers 12A and 12B is sent to the second ECU 35. Detected by the connected hydraulic pressure sensor 32, assist control is performed to increase the pressure of the wheel cylinders 4L and 5R so that the detected value becomes the wheel cylinder pressure corresponding to the detected value as the operation amount of the brake pedal 7. In the assist control, the pressurization control valve 53 and the pressure increase control valves 41 and 42 are opened, and the supply control valve 40 and the pressure reduction control valves 45 and 46 are appropriately opened and closed. In this state, the hydraulic pump 47 is operated by the electric motor 48, and the brake fluid discharged from the hydraulic pump 47 is supplied to the wheel cylinders 4L and 5R via the first and second pipe sections 38 and 39. Thereby, the braking force by the wheel cylinders 4L and 5R can be generated by the brake fluid discharged from the hydraulic pump 47 based on the brake fluid pressure generated on the master cylinder 9 side.

  As the hydraulic pump 47, for example, a known hydraulic pump such as a plunger pump, a trochoid pump, a gear pump, or the like can be used. However, it is desirable to use a gear pump in consideration of on-board performance, quietness, pump efficiency, and the like. As the electric motor 48, a known motor such as a DC motor, a DC brushless motor, an AC motor, or the like can be used. However, in the present embodiment, a DC motor is used from the viewpoint of in-vehicle performance.

  Further, the control valves 40, 41, 42, 45, 46, and 53 of the ESC 33 can have their characteristics appropriately set according to their use modes. Among these, the supply control valve 40 and the pressure increase control valve 41 are set. , 42 are normally open valves, and the pressure-reducing control valves 45, 46 and pressurization control valve 53 are normally closed valves, so that even when there is no control signal from the second ECU 35, the master cylinder 9 to the wheel cylinder 4L. Fluid pressure can be supplied to ~ 5R. Therefore, such a configuration is desirable from the viewpoint of fail-safe and control efficiency of the brake system.

  On the other hand, the vehicle data bus 29 mounted on the vehicle serves as a third control circuit (power charging controller, regenerative cooperative control device) for electrically driving and controlling a motor generator 55 (see FIG. 1) described later. A third ECU 54 is connected. The third ECU 54 is composed of a microcomputer or the like, similar to the first and second ECUs 27 and 35, and, for example, a motor / generator controller (control device) that controls the driving state (power running, regeneration) of the motor / generator 55. It is comprised including.

  In this case, the third ECU 54 uses the inertial force generated by the rotation of the wheels (in the case of the present embodiment, the front wheels 2L and 2R) when the vehicle is decelerated and braked, etc. By controlling the motor / generator 55 which is a motor), a braking force is obtained while recovering (regenerating) kinetic energy as electric power. The third ECU 54 is connected to the first ECU 27 and the second ECU 35 via the vehicle data bus 29, and constitutes a control means (regenerative braking control means) for controlling the regenerative braking amount. Further, the third ECU 54 is connected to the power supply line 30, and power from the battery 31 (see FIG. 1) is supplied through the power supply line 30.

  A motor / generator (MG) 55 as a regenerative braking device connected to the third ECU 54 performs driving to drive the vehicle when the vehicle is accelerated, and the inertial force of the vehicle when the vehicle is decelerated. It is comprised as an electric motor (generator motor) which performs electric power generation (regeneration) based on. That is, the motor / generator 55 functions as a motor (electric motor) that generates torque (rotational force) for running the vehicle based on, for example, electric power stored in a power storage device (not shown) of the vehicle, It serves as a generator (generator) that generates electric power based on the traveling inertia force. In FIG. 1, only the motor / generator 55 is shown as a vehicle drive source. However, for example, in the case of an electric vehicle, the motor / generator 55 serves as a drive source for traveling, and in the case of a hybrid vehicle, the motor / generator 55 An unillustrated engine (internal combustion engine) is a driving source for traveling.

  Next, regenerative cooperative control performed by the third ECU 54 and the first ECU 27 will be described. Here, regenerative cooperative control refers to recovering (regenerating) kinetic energy as electric power by rotating the motor / generator 55 based on the inertial force of the vehicle during deceleration, braking, etc. On the other hand, by subtracting the braking force (regenerative braking force) due to regeneration of the motor / generator 55 and adjusting the braking force (friction braking force) due to the friction lining of the friction braking device 6, the vehicle as a whole can be obtained with both of these braking forces. This is a brake control for obtaining a desired braking force.

  That is, when the brake pedal 7 is operated, in addition to generating the friction braking force for the operation amount of the brake pedal 7 as it is, if the regenerative braking force by the kinetic energy of the motor / generator 55 is generated, the entire vehicle As a result, the braking force becomes excessive. Therefore, in the regenerative cooperative control, the hydraulic pressure of the master cylinder 9 is reduced by an amount corresponding to the regenerative braking force by changing the control amount of the electric booster 17 (electric motor 22) with respect to the operation amount of the brake pedal 7. The desired braking force corresponding to the operation of the brake pedal 7 is obtained by the braking force for friction braking and the braking force for regenerative braking.

  Here, the maximum value of the regenerative braking generated by the regenerative cooperative control is defined by the amount of pressure reduction of the master cylinder 9 that can be realized by changing the control amount of the electric motor 22 of the electric booster 17. Therefore, the required regenerative braking amount is transmitted via the vehicle data bus 29 from the first ECU 27 that controls the electric motor 22 to the third ECU 54 that controls the motor / generator 55. Although this required regenerative braking amount is defined by the first ECU 27, it is the third ECU 54 that actually generates the regenerative braking force by the motor / generator 55, and therefore the required regenerative braking amount and the actual regenerative braking amount. May be different.

  If the actual regenerative braking amount is different from the required regenerative braking amount, the total braking amount between the friction braking amount by the hydraulic pressure and the regenerative braking amount by the motor / generator 55 becomes small. For this reason, there is a possibility that the deceleration is lost or the deceleration is lowered. In order to suppress this loss of deceleration or a decrease in deceleration, the actually generated regenerative braking amount is transmitted from the third ECU 54 to the first ECU 27 via the vehicle data bus 29 as the effective regenerative braking amount. . The first ECU 27 defines a master cylinder 9 pressure reduction amount based on the drive of the electric motor 22 based on the received execution regenerative braking amount, and generates a desired braking force. The effective regenerative braking amount is always set to a value smaller than the required regenerative braking amount.

  By the way, in a vehicle that performs regenerative cooperative control, the following traveling scene may occur. That is, when the driver depresses the brake pedal 7 and the regenerative cooperative control is executed during traveling, the friction braking amount decreases by the regenerative braking amount as described above, so that the driving wheel (in the present embodiment, the front wheel 2L) is reduced. , 2R) is larger than that when the regenerative cooperative control is not performed. At this time, if the force applied to the tire of the drive wheel becomes larger than the frictional force (grip limit) determined by the load applied to the tire and the road surface resistance, the drive wheel may slip. In this case, there is a possibility that an increase in braking distance or early intervention of so-called antilock brake control, in which antilock brake control by the ESC 33 is started earlier than when the regenerative cooperative control is not performed, may occur. In order to prevent these problems, it is necessary to reduce the amount of regenerative braking applied to the drive wheels in the shortest possible time so that the force applied to the tire is within the grip limit.

  However, when the amount of regenerative braking is suddenly changed, the electric booster 17 operates the electric actuator 21. In this case, due to the response delay until the desired hydraulic pressure is generated, the sum of the regenerative braking amount and the friction braking amount generated in the vehicle is reduced below the braking force intended by the driver, and the deceleration is lost. May occur. Further, since the braking amount moves from the drive wheels (front wheels 2L, 2R) to the driven wheels (3L, 3R), a sudden load movement occurs in the front and rear wheels. In this case, understeer occurs during turning, and the vehicle behavior may become unstable.

  Therefore, in order to reduce the regenerative braking amount so that the slip converges early, the regenerative braking amount is held after reducing the regenerative braking amount so that the force applied to the tire becomes the grip limit. And the fluctuation | variation of the deceleration by the response delay until the electric booster 17 operates the electric actuator 21 and generate | occur | produces a desired hydraulic pressure is prevented. Furthermore, when the slip does not converge, the regenerative braking amount is reduced so as to suppress the slip early while suppressing the deceleration variation by repeatedly reducing and maintaining the regenerative braking amount so that the deceleration variation does not occur again. It needs to be reduced.

  Further, as shown in FIG. 3, during turning braking, a resultant force of the vertical direction (braking force) and the horizontal direction (lateral force) is applied to the tire. If the same amount of regenerative braking is generated during straight braking and during turning braking, lateral force is applied to the tire during turning braking compared to straight braking, so regenerative braking necessary to suppress vehicle slippage. It is necessary to set the amount larger by the amount of lateral force. That is, as shown in FIG. 3, the amount of decrease in the regenerative braking amount required during turning braking is larger by the difference amount ΔC than the amount of decrease in the regenerative braking amount required during straight braking. The magnitude of the difference amount ΔC is variably set based on the magnitude of the lateral force (lateral G).

  Therefore, in the present embodiment, when the slip amount of the front wheels 2L and 2R serving as drive wheels is detected, the amount of decrease in the regenerative braking amount is made variable according to the turning amount of the vehicle. That is, the reduction amount of the regenerative braking amount corresponding to the lateral force applied to the tire during turning braking is set larger than the reduction amount of the regenerative braking amount during straight braking. As a result, during turning braking, the slip is converged at an early stage in the same way as during straight braking, so that it is possible to suppress changes in vehicle behavior and early intervention in antilock brake control. For this purpose, the second ECU 35 includes a slip amount detector 56 as a slip amount detecting means for detecting slip amounts of wheels 2L, 2R, 3L, 3R provided in the vehicle, and a turning amount detector 57. It is connected.

  The slip amount detector 56 can be constituted by, for example, a wheel speed sensor that detects the rotational speed of each wheel 2L, 2R, 3L, 3R. In this case, the slip amount of the front wheels 2L and 2R serving as driving wheels is calculated based on the difference between the rotational speed of the front wheels 2L and 2R serving as driving wheels and the rotational speed of the rear wheels 3L and 3R serving as driven wheels. Can do. Further, the slip amount detector 56 can be constituted by, for example, a wheel speed sensor that detects the rotational speed of the front wheels 2L and 2R that are drive wheels and a vehicle speed sensor that detects the rotational speed of the transmission rotation shaft. In this case, based on the difference between the wheel speed detected by the wheel speed sensor and the vehicle speed (body speed, vehicle speed) detected by the vehicle speed sensor, the slip amounts of the front wheels 2L and 2R serving as drive wheels are calculated. be able to. In FIGS. 1 and 2, for convenience of explanation, the slip amount detector 56 and the second ECU 35 of the ESC 33 are described separately. However, a slip amount detection function may be incorporated in the second ECU 35. In this case, a wheel speed sensor for detecting the rotational speed of each wheel 2L, 2R, 3L, 3R is connected to the second ECU 35.

  The turning amount detector 57 can be configured by an acceleration sensor that detects the lateral G of the vehicle, for example. In this case, it can be determined whether the vehicle is turning based on the lateral G detected by the acceleration sensor. Further, the turning amount detector 57 can be constituted by, for example, a wheel speed sensor that detects the rotational speed of the wheel and a steering angle sensor that detects the steering angle of the driver. In this case, the lateral G generated by the vehicle speed detected by the wheel speed sensor and the steering angle detected by the steering angle sensor can be calculated.

  On the other hand, for example, the first ECU 27 detects the wheel (specifically, based on the detection value of the slip amount detector 56 received via the second ECU 35 and the vehicle data bus 29 during regenerative braking by the motor / generator 55. When it is detected that the front wheels 2L and 2R) serving as driving wheels are slipping, regenerative slip control means (processing of FIG. 4 described later) for reducing the regenerative braking amount of the motor / generator 55 is provided. . This regenerative slip control means is used for the motor while the front wheels 2L and 2R serving as drive wheels are slipping based on the detection value of the slip amount detector 56 during regenerative braking by the motor / generator 55. -After reducing the regenerative braking amount of the generator 55 by a predetermined amount, the slip suppression control for holding the reduced regenerative braking amount for a predetermined time is repeatedly performed.

  In this case, in the regenerative slip control means, the regenerative braking amount when the drive wheels (front wheels 2L, 2R) are detected to be slipping is regenerated based on the detection value of the turning amount detector 57. The amount of reduction of the braking amount is variable, and after the regenerative braking amount is decreased by a predetermined amount according to the turning amount, the regenerative braking amount is held for a predetermined time. In this case, for example, as indicated by a characteristic line 58 shown in FIG. 5, a map of a reduction amount of the regenerative braking amount (first predetermined reduction amount) at the time of turning braking corresponding to the lateral G is stored in the first ECU 27. . Note that the characteristic line 58 for turning braking shown in FIG. 5 is a linear characteristic (linear characteristic), but the relationship between the lateral force (lateral G) and the amount of decrease in the regenerative braking amount depends on the resistance between the tire and the road surface. In some cases, nonlinear characteristics (non-linear characteristics) may be obtained. That is, the characteristic line for turning braking is set in advance based on experiments, calculations, simulations, and the like.

  Then, the regenerative braking amount is decreased while the slip occurs thereafter. In this case, the reduction amount of the regenerative braking amount (for example, the second predetermined reduction amount) is set to a smaller value than the initial predetermined reduction amount set after the slip detection so that the deceleration fluctuation does not occur. ing. That is, as shown in FIG. 6, the regenerative slip control means reduces the regenerative braking amount of the motor / generator 55 when the slip amount of the drive wheels (front wheels 2L, 2R) is equal to or greater than the slip threshold, thereby Reduce the amount step by step. As a result, during straight braking and during turning braking, the electric booster 17 operates the electric actuator 21 to prevent a speed fluctuation due to a delay in response until a desired hydraulic pressure is generated, and prevent slipping at an early stage. Suppression can be realized and vehicle behavior can be kept stable. The process of FIG. 4 executed by the first ECU 27 will be described later.

  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 7, the input rod 20 is pushed in the direction indicated by arrow A, and a detection signal from the operation amount detection sensor 8 is input to the first ECU 27. The first ECU 27 controls the operation of the electric actuator 21 of the electric booster 17 according to the detected value. That is, the first ECU 27 supplies power to the electric motor 22 based on the detection signal from the operation amount detection sensor 8 and rotationally drives the electric motor 22. In this case, the first ECU 27 subtracts the braking force (regenerative braking force) due to regeneration of the motor / generator 55 from the braking force (braking force of the entire vehicle) intended by the driver according to the stroke amount of the brake pedal 7. In addition, the braking force (friction braking force) to be generated by the friction braking device 6 is calculated, and the electric motor 22 is supplied with power so that the hydraulic pressure required to obtain the braking force is obtained. Is driven to rotate.

  The rotation of the electric motor 22 is transmitted to the cylindrical rotating body 23 via the speed reduction mechanism 24, and the rotation of the cylindrical rotating body 23 is converted into the axial displacement of the booster piston 19 by the linear motion mechanism 25. As a result, the booster piston 19 of the electric booster 17 is displaced in the forward direction toward the cylinder body 10 of the master cylinder 9, and the pedaling force (thrust) applied from the brake pedal 7 to the input rod 20 and the electric actuator 21. Thus, a brake fluid pressure corresponding to the booster thrust applied to the booster piston 19 is generated in the first and second fluid pressure chambers 12A and 12B of the master cylinder 9.

  Next, the ESC 33 provided between the wheel cylinders 4L, 4R, 5L, 5R on the side of each wheel (front wheels 2L, 2R and rear wheels 3L, 3R) and the master cylinder 9 is 9 (the first and second hydraulic pressure chambers 12A and 12B), the hydraulic pressure as the master cylinder pressure is transferred from the cylinder side hydraulic pipes 16A and 16B to the hydraulic systems 36 and 36 'in the ESC 33 and the brake side. While being variably controlled to the wheel cylinders 4L, 4R, 5L, and 5R via the piping portions 34A, 34B, 34C, and 34D, the wheel cylinder pressure is distributed and supplied for each wheel. Thus, an appropriate braking force is applied to the vehicle wheels (respective front wheels 2L, 2R, rear wheels 3L, 3R) via the wheel cylinders 4L, 4R, 5L, 5R.

  Further, the second ECU 35 that controls the ESC 33 supplies power to the electric motor 48 based on a detection signal from the operation amount detection sensor 8 received through the signal line 28 and operates the hydraulic pumps 47 and 47 ′. The control valves 40, 40 ', 41, 41', 42, 42 ', 45, 45', 46, 46 ', 53, 53' are selectively opened and closed. Thereby, braking force distribution control, anti-lock brake control, vehicle stabilization control, slope start assistance control, traction control, vehicle following control, lane departure avoidance control, obstacle avoidance control, and the like can be executed. In particular, in the antilock brake control, when the slip amounts of the wheels 2L, 2R, 3L, 3R detected by the slip amount detector 56 continuously exceed the antilock slip threshold for a predetermined time, the control valves 40, 40 are controlled. ', 41, 41', 42, 42 ', 45, 45', 46, 46 ', 53, 53' are selectively opened and closed to reduce the brake pressure of the wheel cylinders 4L, 4R, 5L, 5R. The slip (lock) of the wheels 2L, 2R, 3L, 3R is suppressed by holding and increasing the pressure.

  By the way, in the prior art by the above-mentioned patent document 1, the slip of the vehicle which generate | occur | produces by regenerative braking is detected from vehicle body speed and wheel speed. In order to suppress the generated slip, the regenerative braking amount is decreased by a preset value. As a result, the braking force of the drive wheels is reduced so that the force applied to the tire is within the friction force (grip limit) determined by the load applied to the tire and the resistance of the road surface.

  Here, the force applied to the tire during straight braking is only the longitudinal direction (braking force), but the force applied to the tire during turning braking is a force obtained by adding a lateral direction (lateral force) to the braking force. That is, the force applied to the tire during turning braking is a resultant force in the vertical direction (braking force) and the horizontal direction (lateral force). Therefore, in order to keep the force applied to the tire during turning braking within the grip limit of the tire, it is necessary to reduce the regenerative braking amount in consideration of the lateral force.

  However, the conventional technique is configured to reduce a preset regenerative braking amount. Therefore, the regenerative braking amount that should be decreased to suppress slip during turning braking may be smaller by the lateral force than the regenerative braking amount that is decreased to suppress slip during straight braking. As a result, the time required for the force applied to the tire to decrease to the grip limit becomes long, so that there is a problem that the convergence of the slip is delayed, the vehicle behavior becomes unstable, and the braking distance becomes long.

  Therefore, in the present embodiment, the regenerative braking amount to be decreased when it is detected that the front wheels 2L and 2R serving as drive wheels are slipping is made variable based on the detection value of the turning amount detector 57. Thereby, at the time of turning braking, it is possible to set a reduction amount of the regenerative braking amount by increasing the lateral force applied to the tire compared to the straight braking. As a result, slippage can be suppressed during turning braking as well as during straight braking, and the vehicle behavior can be kept stable.

  Next, regenerative control processing (regenerative slip suppression processing) performed by the first ECU 27 will be described with reference to the flowchart of FIG. Note that the process of FIG. 4 is repeatedly executed by the first ECU 27 every predetermined control time (with a predetermined control cycle) while the first ECU 27 is energized.

  When the first ECU 27 is energized (or the driver operates the brake pedal 7 while the vehicle is running) and the processing operation of FIG. 4 is started, the first ECU 27 is driven in step 1. The slip amount of the front wheels 2L and 2R serving as the wheels is calculated. This slip amount is performed based on the detection value of the slip amount detector 56. For example, when the slip amount detector 56 is constituted by a wheel speed sensor that detects the rotational speed of each of the wheels 2L, 2R, 3L, 3R, the rotational speed of the front wheels 2L, 2R serving as driving wheels and the rear wheel serving as a driven wheel. Based on the difference between the rotational speeds of 3L and 3R, the slip amount of the front wheels 2L and 2R serving as drive wheels can be calculated. The slip amount can also be calculated based on the difference between the wheel speed detected by the wheel speed sensor and the vehicle speed (body speed, vehicle speed) detected by the vehicle speed sensor.

  In the subsequent step 2, it is determined whether or not the slip amount calculated in step 1 is greater than or equal to the slip threshold. Here, because the braking amount of the driving wheels (front wheels 2L, 2R) is greater than the frictional force (grip limit) determined by the load applied to the tire and the resistance of the road surface, the braking threshold of the driving wheels is set. This is a determination value (threshold value) for determining whether or not it is necessary to suppress slip at an early stage. The slip threshold is a determination value determined by the magnitude of friction between the load applied to the tire and the road surface, and is set in advance based on experiments, calculations, simulations, and the like. In this case, the load applied to the drive wheels may be corrected by, for example, limiting or adding to the slip threshold by detecting the roll angle and pitch angle of the vehicle from an acceleration sensor.

  If “YES” in step 2, that is, if it is determined that the slip amount calculated in step 1 is greater than or equal to the slip threshold, the slip amount is large, the braking distance is increased, and the vehicle behavior caused by understeer during braking is generated. Since there is a risk of deterioration and early anti-lock brake control intervention, the process proceeds to Step 3. On the other hand, if it is determined “NO” in step 2, that is, if the slip amount calculated in step 1 is less than the slip threshold, the process proceeds to step 7.

  In step 3, the turning amount (lateral G) is calculated. The turning amount is calculated by detecting the lateral G from the acceleration sensor as the turning amount detector 57. The lateral G generated in the vehicle may be calculated based on the vehicle speed detected by the wheel speed sensor that detects the rotational speed of the wheel and the detected value from the steering angle sensor that detects the steering angle of the driver.

  In the next step 4, the regenerative braking amount reduction amount and the holding time are set based on the turning amount calculated in step 3. In this case, the amount of decrease in the regenerative braking amount that is set at the time of straight braking (that is, when the lateral G is zero in Step 3) is reduced after it is determined in Step 2 that the slip amount is equal to or greater than the slip threshold. Therefore, it is necessary to make a setting so as to compensate for the regenerative braking amount that increases until the tire starts and the grip limit that is reduced when the resistance to the road surface is switched from static friction to dynamic friction when the tire starts to slip. Accordingly, the amount of decrease in the regenerative braking amount set during straight braking is dependent on the resistance between the tire and the road surface, and the value is set based on experiments, calculations, simulations, and the like in advance.

  On the other hand, as shown in FIG. 3, the amount of decrease in the regenerative braking amount set during turning braking (that is, when the lateral G is generated in step 3) is the difference amount ΔC for the lateral force with respect to the straight braking. It is necessary to increase by minutes. The lateral force can be calculated by adding the load applied to the driving wheel to the calculated lateral G. In this case, the load applied to the driving wheel may be estimated and calculated by detecting the roll angle and pitch angle of the vehicle from an acceleration sensor, for example. Then, as shown in FIG. 5, during turning braking, the amount of decrease in the regenerative braking amount corresponding to the lateral G is added to the amount of decrease during straight braking.

  The holding time is set in order to suppress the occurrence of a decrease in deceleration due to a response delay until the electric booster 17 operates the electric actuator 21 to generate a desired hydraulic pressure. The setting of the holding time may be variably set corresponding to the amount of decrease in the regenerative braking amount so that the reduction in deceleration does not occur due to, for example, a response delay until the desired hydraulic pressure is generated.

  In the next step 5, the regenerative braking amount is decreased by the set decrease amount. That is, the regenerative braking amount is decreased based on the regenerative braking amount reduction amount set in step 4, and the process proceeds to the next step 6.

  In step 6, it is determined whether or not the set holding time has elapsed after the regenerative braking amount is decreased. That is, it is determined whether or not the regenerative braking amount after reduction set in step 4 has continued for the set holding time. If it is determined in step 6 that “YES”, that is, the set holding time has elapsed, the process returns. On the other hand, if it is determined in step 6 that “NO”, that is, the set holding time has not elapsed, monitoring is performed until the set holding time has elapsed. Thereby, it is possible to prevent a decrease in deceleration due to a response delay until the electric booster 17 operates the electric actuator 21 to generate a desired hydraulic pressure.

  On the other hand, in step 7 when “NO” is determined in step 2, it is determined whether or not the slip amount is equal to or greater than the target slip amount. That is, it is determined whether or not the slip amount calculated in Step 1 has converged sufficiently low. Here, the target slip amount is specifically for determining whether or not the regenerative braking amount needs to be continuously decreased in order to converge the braking amount slip of the driving wheels (front wheels 2L and 2R). It is a judgment value. When it is determined in step 2 that the regenerative braking amount does not need to be reduced at the slip threshold in step 2, the target slip amount is increased depending on vehicle behavior such as an increase in stop distance and understeer during turning due to the generated slip amount. The value is set in advance based on experiments, calculations, simulations, etc. within a range where no adverse effect occurs.

  If it is determined in step 7 that “NO”, that is, the slip amount is less than the target slip amount, the regenerative braking amount is set since the slip amount is sufficiently small and does not adversely affect the vehicle behavior. Returns without restriction. On the other hand, if “YES” in step 7, that is, if it is determined that the slip amount is equal to or greater than the target slip amount, the process proceeds to step 8.

  In step 8, a reduction amount and a holding time of the regenerative braking amount for tracking the target slip are set. In this case, the regenerative braking amount reduction amount for reducing the slip amount to the target slip amount is set to a value smaller than the regenerative braking amount reduction amount in step 4. Specifically, the amount of decrease in the regenerative braking amount for reducing the slip amount to the target slip amount (the amount of decrease in the regenerative braking amount for tracking the target slip) is set to a value that does not cause deceleration fluctuations. Yes. The holding time is set to a response time until the electric booster 17 operates the electric actuator 21 and generates a desired hydraulic pressure with respect to the set amount of reduction of the regenerative braking amount.

  In the next step 5, the regenerative braking amount is decreased by the set decrease amount. That is, the regenerative braking amount is decreased based on the regenerative braking amount reduction amount set in step 8, and the process proceeds to the next step 6.

  In step 6, it is determined whether or not the set holding time has elapsed after the regenerative braking amount is decreased. That is, it is determined whether or not the regenerative braking amount after reduction set in step 8 has continued for the set holding time. If it is determined in step 6 that “YES”, that is, the set holding time has elapsed, the process returns. On the other hand, if it is determined in step 6 that “NO”, that is, the set holding time has not elapsed, monitoring is performed until the set holding time has elapsed. Thereby, it is possible to prevent a decrease in deceleration due to a response delay until the electric booster 17 operates the electric actuator 21 to generate a desired hydraulic pressure.

  Next, the setting of the reduction amount of the regenerative braking amount will be described with reference to FIG. 3, FIG. 5, and FIG.

  First, as shown in FIG. 6, at the time of linear braking, when the slip amount of the drive wheels (front wheels 2L, 2R) is equal to or greater than the slip threshold, the first regenerative braking amount (first regenerative braking amount) is linearly braked. Decrease below the braking amount that is the grip limit at the time. In this case, since the turning amount is zero during the straight braking, a preset reduction amount of the regenerative braking amount (see FIG. 5) is set.

  Thereafter, the reduction and holding of the regenerative braking amount are repeated in stages until the slip amount becomes equal to or less than the target slip amount. In this case, the predetermined decrease amount of the second regenerative braking is set smaller than the predetermined decrease amount of the first regenerative braking. Thereby, since it can suppress that the excessive braking amount continues, a vehicle behavior can be kept stable. Further, by providing the holding time, it is possible to suppress a decrease in the deceleration of the vehicle.

  Next, as shown in FIG. 6, during turning braking, the first regenerative braking amount (first regenerative braking amount) is turned when the slip amount of the drive wheels (front wheels 2L, 2R) is equal to or greater than the slip threshold. Decrease to below the braking amount that will be the grip limit during braking. In this case, as shown in FIG. 3, the amount of decrease in the regenerative braking amount required during turning braking is made larger by the difference amount ΔC than the regenerative braking amount required during straight braking by the amount of lateral force applied to the tire during turning braking. .

  Therefore, the vehicle body 1 is provided with a turning amount detector 57 that detects the lateral G of the vehicle. Then, the first ECU 27 calculates a decrease amount of the regenerative braking amount for turning braking according to the characteristic line 58 shown in FIG. 5 based on the lateral G detected by the turning amount detector 57. In this case, a difference amount (ΔC) between the regenerative braking amount for rectilinear braking and the decrease amount of the regenerative braking amount for turning braking is calculated, and a difference amount is added to the preset reduction amount of the regenerative braking amount during rectilinear braking. A decrease amount of the regenerative braking amount for turning braking may be calculated by adding (ΔC). Further, the reduction amount of the regenerative braking amount for turning braking may be calculated using a calculation formula set in advance by experiment or the like.

  Thereafter, the reduction and holding of the regenerative braking amount are repeated in stages until the slip amount becomes equal to or less than the target slip amount. In this case, the predetermined decrease amount of the second regenerative braking is set smaller than the predetermined decrease amount of the first regenerative braking. Thereby, since it can suppress that the excessive braking amount continues, a vehicle behavior can be kept stable. Further, by providing the holding time, it is possible to suppress a decrease in the deceleration of the vehicle.

  Thus, according to the first embodiment, when the slip amount is detected in the front wheels 2L and 2R serving as drive wheels, a large deceleration fluctuation is generated by reducing the regenerative braking amount of the motor / generator 55. Without this, the regenerative braking force applied to the front wheels 2L and 2R can be reduced early. Then, the predetermined decrease amount of the first regenerative braking when it is detected that the front wheels 2L and 2R are slipping is set to the predetermined decrease of the second regenerative braking in the slip suppression control after the predetermined hold time has elapsed. It is set to be larger than the amount and changed according to the turning amount of the vehicle.

  As a result, it is possible to suppress a state in which an excessive amount of regenerative braking is applied to the drive wheels even during turning braking as in the case of straight braking. After that, the regenerative braking amount is maintained and the slip amount becomes the target slip amount so that the deceleration fluctuation due to the response delay until the electric booster 17 operates the electric actuator 21 to generate the desired hydraulic pressure does not occur. The reduction and holding of the regenerative braking amount are repeated step by step until it becomes less than. Thereby, it is possible to converge the slip at an early stage, to suppress an increase in braking distance, to suppress understeer that occurs during turning, and to suppress early intervention of antilock brake control.

  Next, FIG. 7 shows a second embodiment of the present invention. The feature of this embodiment is that the predetermined reduction amount of the first regenerative braking is divided into a plurality of parts. In the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  Since the lateral force increases when the turning amount is large, the reduction amount of the first regenerative braking that reduces the regenerative braking amount to be equal to or less than the braking amount that becomes the grip limit at the time of turning braking is also increased. In this case, if the reduction amount of the first regenerative braking is increased in order to suppress slip early, the braking force suddenly moves from the driving wheels (front wheels 2L, 2R) to the driven wheels (rear wheels 3L, 3R). It will be. As a result, a sudden load (wheel load) movement occurs between the front wheels 2L, 2R and the rear wheels 3L, 3R, which may cause unstable vehicle behavior.

  Therefore, when the predetermined reduction amount of the first regenerative braking is equal to or greater than the limit value, the predetermined reduction amount of the first regenerative braking is divided into a plurality (two stages). This limit value is due to a decrease in the load applied to the driving wheels (front wheels 2L, 2R) due to the load movement between the front and rear wheels when the regenerative braking amount is reduced, and as the grip limit rapidly decreases, the understeer is reduced. Set in a range that does not occur. In this case, the limit value based on the load movement between the front and rear wheels is set based on experiments, calculations, simulations, and the like in advance because the grip limit of the tire depends on the resistance between the tire and the road surface. The load movement between the front and rear wheels may be detected by, for example, an acceleration sensor in the front-rear direction, or can be obtained by a detection signal from a vehicle height sensor on the front and rear wheels. It can also be detected by a vehicle pitch sensor or the like.

  Thus, also in the second embodiment, the vehicle behavior can be kept stable and the braking distance can be shortened, as in the first embodiment. In particular, in the second embodiment, a limit value is provided for the reduction amount of the regenerative braking amount, the braking amount that moves from the driving wheel to the driven wheel at one time is limited, and the holding time is divided to suppress load movement. As a result, it is possible to suppress an increase in braking distance, suppress understeer that occurs during turning, and suppress early intervention in antilock brake control while preventing sudden load movement.

  In the above-described first embodiment, the case where the control process shown in FIG. 4 is performed by the first ECU 27 has been described as an example. However, the present invention is not limited to this. For example, the control process shown in FIG. 4 may be performed by the third ECU 54 or the second ECU 35. Moreover, it is good also as a structure performed by ECU arrange | positioned at the other vehicle. The same applies to the second embodiment.

  Further, in the first embodiment described above, the case where the slip amount detector 56 and the turning amount detector 57 are configured to be connected to the second ECU 35 has been described as an example. However, the present invention is not limited to this, and the slip amount detector 56 and the turning amount detector 57 may be connected to, for example, the first ECU 27 or the third ECU 54. Moreover, it is good also as a structure connected to ECU arrange | positioned at the other vehicle. The same applies to the second embodiment.

  In the second embodiment described above, the predetermined reduction amount of the first regenerative braking is divided into two stages. However, the present embodiment is not limited to this. For example, the predetermined reduction amount of the first regenerative braking may be divided into three or more stages.

  Further, in the above-described embodiment, the case where the front wheels 2L and 2R are configured to be driven by the motor / generator 55 serving as an electric motor for driving a vehicle (for driving a vehicle) has been described as an example. That is, the case where the driving wheels are the front wheels 2L and 2R has been described as an example. However, the present invention is not limited to this, for example, a configuration in which a rear wheel is driven by a motor / generator (electric motor) (a driving wheel is a configuration of a rear wheel), or a configuration in which a front wheel and a rear wheel (four wheels) are driven (a driving wheel is It may be a configuration of front and rear wheels.

  As a brake control device based on the embodiment described above, for example, the following embodiment can be considered.

  As a first aspect, the amount of regenerative braking of a regenerative motor provided in the vehicle is controlled, and the vehicle is braked by controlling a friction braking device that is provided on each wheel and has a friction member that receives hydraulic pressure and moves. A brake control device for detecting the slip amount of the wheel, and when the detected value of the slip amount detection means exceeds a slip threshold during regenerative braking by the regenerative motor, the wheel Regenerative slip control means for repeatedly performing slip suppression control for holding the reduced regenerative braking amount for a predetermined time after the regenerative braking amount is reduced by a predetermined amount. The regenerative slip control means calculates a predetermined decrease amount of the first regenerative braking when it is detected that the wheel is slipping, after the predetermined hold time has elapsed. Tsu larger than the predetermined reduction amount of the second regenerative braking at up suppression control, and is set by varying depending on the turning amount of the vehicle.

  As a second aspect, in the first aspect, when the predetermined decrease amount of the first regenerative braking when it is detected that the wheel is slipping is larger than a limit value, The predetermined reduction amount of one regenerative braking is divided into a plurality of times, and the regenerative braking amount is reduced by the time the predetermined holding time has elapsed.

2L, 2R Front wheel 3L, 3R Rear wheel 6 Friction braking device 7 Brake pedal 17 Electric booster 27 First ECU
33 Hydraulic supply system (ESC)
35 Second ECU
54 Third ECU
55 Motor generator (regenerative motor)
56 Slip amount detector (slip amount detecting means)
57 Turning amount detector

Claims (2)

A brake control device that controls a regenerative braking amount of a regenerative motor provided in a vehicle and brakes the vehicle by controlling a friction braking device that is provided on each wheel and has a friction member that moves under a hydraulic pressure. ,
Slip amount detecting means for detecting the slip amount of the wheel;
During regenerative braking by the regenerative motor, when the detected value of the slip amount detection means exceeds a slip threshold, it is determined that the wheel is slipping, and the regenerative braking amount is decreased by a predetermined amount and then decreased. Regenerative slip control means for repeatedly performing slip suppression control for holding the regenerative braking amount for a predetermined time,
The regenerative slip control means calculates a predetermined decrease amount of the first regenerative braking when it is detected that the wheel is slipping, and a second regenerative slip in the slip suppression control when a predetermined holding time elapses thereafter. A brake control device, wherein the brake control device is set to be larger than a predetermined reduction amount of braking and to be changed according to a turning amount of the vehicle.   If the predetermined reduction amount of the first regenerative braking when it is detected that the wheel is slipping is larger than a limit value, the predetermined reduction amount of the first regenerative braking is divided into a plurality of values. The brake control device according to claim 1, wherein the regenerative braking amount is reduced before the predetermined holding time elapses.

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