BRAKE CONTROL DEVICE

Abstract

The present invention provides a brake control device suitable for reducing the number of electromagnetic valves and achieving cost savings. A shut-off valve of a first hydraulic pressure unit is controlled by both a first control unit and a second control unit.

Description

TECHNICAL AREA

[0001] The present invention relates to a brake control device. STATE OF THE ART

[0002] PTL 1 discloses a brake control device with two hydraulic pressure generating devices suitable for generating brake hydraulic pressure in a fluid channel connecting a master cylinder and a wheel cylinder, independently of any brake actuation. The first hydraulic pressure generating device is controlled by a first control device, and the second hydraulic pressure generating device is controlled by a second control device. The first control device performs a brake-by-wire (BBW) control operation in which a wheel cylinder hydraulic pressure is generated corresponding to a setpoint wheel cylinder hydraulic pressure, while a shut-off valve of the first hydraulic pressure generating device is closed to block the connection between the master cylinder and the wheel cylinder, thus creating a so-called brake-by-wire state (hereinafter referred to as BBW).The second control device performs ESC control, TCS control, and ABS control by controlling the second hydraulic pressure generating device. QUOTE LIST PATENT LITERATURE

[0003] PTL 1: International Publication No. 2016-120292 SUMMARY OF THE INVENTIONAL PROBLEM

[0004] The conventional brake control device discussed in patent literature PTL 1 described above requires that the second control device continue the ESC control or the like by actuating an inlet valve and an outlet valve of the second hydraulic pressure generating device and introducing and discharging brake fluid into a second pump when a fault occurs in the first control device. Therefore, the conventional brake control device described in PTL 1 suffers from the problem that it requires many solenoid valves, leading to increased costs. One of the objectives of the present invention is to provide a brake control device suitable for reducing the number of solenoid valves and thus achieving a reduction in costs. SOLUTION TO THE PROBLEM

[0005] In a brake control device according to one aspect of the present invention, a shut-off valve of a first hydraulic pressure generating device is controlled by both a first control device and a second control device.

[0006] Therefore, if a fault has occurred in the first control device, the second control device can continue the ESC control or the like by controlling the shut-off valve, thus eliminating the need for an inlet valve and an outlet valve in the second hydraulic pressure generating device, thereby reducing the number of electromagnetic valves and achieving a cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows the configuration of a master cylinder unit 5 and a first unit 6 of a brake control device 1 according to a first embodiment. Fig. Figure 2 shows the configuration of a second unit 7 of the brake control device 1 according to the first embodiment. Fig. Figure 3 shows the configuration of a first unit 501 of a brake control device 500 according to a second embodiment. Fig. Figure 4 shows the configuration of an electric piston 502 of the brake control device 500 according to the second embodiment. DESCRIPTION OF THE EXECUTION FORMS [First embodiment]

[0007] Fig. Figure 1 shows the configuration of a master cylinder unit 5 and a first unit 6 of a brake control device 1 according to a first embodiment. Fig. Figure 2 shows the configuration of a second unit 7 of the brake control device 1. The brake control device 1 according to the first embodiment is used for an electric vehicle. Examples of the electric vehicle include an electric car that uses a motor as a drive source to power the wheels, and a hybrid vehicle that uses an internal combustion engine and a motor as drive sources. The brake control device 1 can also be used in a vehicle that uses only an internal combustion engine as a drive source. In each drawing, the P placed at the end of a reference numeral indicates that this section corresponds to a primary system (a P-system) of a master cylinder 2. The S placed at the end of a reference numeral indicates that this section corresponds to a secondary system (an S-system) of the master cylinder 2. In the following, the reference numerals P and S are omitted when the P- and S-systems are not to be distinguished from one another.The letter A at the end of a reference numeral indicates that this section corresponds to the front left wheel FL. Similarly, b, c, and d at the end indicate that these sections correspond to a front right wheel FR, a rear left wheel RL, and a rear right wheel RR, respectively. If these wheels FL through RR are not distinguished from one another, the suffixes a, b, c, and d are omitted.

[0008] The brake control device 1 generates a brake hydraulic pressure in a wheel cylinder 3 (a wheel cylinder hydraulic pressure) using a hydraulic brake, thereby pressing brake pads provided on each of the wheels FL to RR against a brake disc provided on the wheel side to exert a braking force on each of the wheels FL to RR. A brake pedal 4 is a brake actuation element that receives input from a driver's brake application. The brake pedal 4 is a so-called suspended brake pedal, and the proximal end of the pedal is rotatably mounted by a shaft 401. One end of a push rod 403 is rotatably connected by a shaft 404 to the brake pedal 4 at its proximal end between the shaft 401 and a footpad 402. A stroke sensor 12 is provided on the brake pedal 4.The stroke sensor 12 detects an axial displacement quantity of the push rod 403 as a physical quantity in relation to an actuation volume of the brake pedal 4 (a brake actuation volume).

[0009] The brake control device 1 according to the first embodiment comprises the master cylinder unit 5, the first unit 6, and the second unit 7. The master cylinder unit 5 is a single unit in which the master cylinder 2 and a reservoir 9 are integrally provided. The master cylinder 2 is actuated by the driver's actuation of the brake pedal 4 (a brake actuation) and generates a brake hydraulic pressure (a master cylinder hydraulic pressure) corresponding to the degree of brake actuation. The master cylinder 2 does not include a vacuum booster that increases or amplifies the force of the driver's brake actuation (the force with which the brake pedal 4 is actuated), for example, by using the engine's intake vacuum. The master cylinder 2 is connected to the brake pedal 4 via the pushrod 403 and is also supplied with brake fluid from the reservoir 9.The master cylinder 2 is a tandem master cylinder and comprises a primary piston 11P and a secondary piston 11S in series as master cylinder pistons, which are axially movable according to the brake actuation. The primary piston 11P is connected to the pushrod 403. The secondary piston 11S is configured as a free piston.

[0010] The reservoir 9 is a brake fluid source in which the brake fluid is stored and is a low-pressure section open to atmospheric pressure. The interior of the reservoir 9 is divided into three compartments by partitions (not shown). A primary reservoir chamber supplies brake fluid to the primary chamber 16P of the master cylinder 2. A secondary reservoir chamber supplies brake fluid to the secondary chamber 16S of the master cylinder 2. A suction reservoir chamber is connected via a suction hose 21 to an internal fluid pool chamber 43 of a first hydraulic pressure unit (a first hydraulic pressure generating device) 105 and to a pressure reducing fluid channel 231 of a second hydraulic pressure unit (a second hydraulic pressure generating device) 106, which are described below.

[0011] The first unit 6 is a unit in which a lifting simulator 13, the first hydraulic pressure unit 105, and a first control unit (a first control device) 18 are integrally provided. The lifting simulator 13 is actuated according to the driver's brake application. The primary piston 11P of the master cylinder 2 is moved according to the driver's brake application, and the brake fluid thereby expelled flows into the lifting simulator 13, generating the pedal stroke. The interior of the lifting simulator 13 is divided into two chambers, a positive pressure chamber 35 and a counter-pressure chamber 36, and a simulator piston 14 is inserted into a cylinder section formed within a simulator housing 15. A fluid passage 28, which is described below, is open to the inner circumferential surface of the counter-pressure chamber 36.

[0012] The simulator piston 14 is sealed by a sleeve seal 37. The sleeve seal 37 allows brake fluid to flow only from the counter-pressure chamber 36 to the positive pressure chamber 35 and prevents brake fluid from flowing from the positive pressure chamber 35 to the counter-pressure chamber 36. Therefore, a pressure is generated in the positive pressure chamber 35 due to an inflow from the master cylinder side 2 into the stroke simulator 13, which moves the simulator piston 14. Two spring elements 30a and 30b and a rubber element 32 are held in the counter-pressure chamber 36 by means of a bracket 38 and a plug 33. When the simulator piston 14 is moved, a reaction force is generated due to the compression of both the spring elements 30a and 30b and the rubber element 32.As a result, a natural pedal feel is created by establishing a balance between the pressure in the positive pressure chamber 35 and the reaction force generated by the compression of both the spring elements 30a and 30b as well as the rubber element 32.

[0013] The first hydraulic pressure unit 105 is connected to the master cylinder 2 via master cylinder pipes 10. Furthermore, the first hydraulic pressure unit 105 is connected to the suction chamber of the reservoir 9 via the suction hose 21. The first hydraulic pressure unit 105 and the second hydraulic pressure unit 106 are connected to each other via unit connecting pipes 23. The second hydraulic pressure unit 106 is connected to the wheel cylinders 3 via wheel cylinder lines 22. The brake control device 1 uses a so-called X-pipe configuration (cross-pipe configuration), in which the primary system of the second hydraulic pressure unit 106 is connected to the front left wheel cylinder 3a and the rear right wheel cylinder 3d, while the secondary system is connected to the front right wheel cylinder 3b and the rear left wheel cylinder 3c.The brake control device 1 can use an H-shaped piping system in which the front wheels are connected to the primary system and the rear wheels to the secondary system.

[0014] The first hydraulic pressure unit 105 comprises first inlet ports 110, a suction port 111, and first outlet ports 112. The first inlet port 110P of the P-system is connected to the main cylinder line 10P. The first inlet port 110S of the S-system is connected to the main cylinder line 10S. The suction port 111 is connected to the suction hose 21. The first outlet port 112P of the P-system is connected to the implement connection line 23P. The first outlet port 112S of the S-system is connected to the implement connection line 23S. The first inlet port 110P and the first outlet port 112P of the P-system are connected to each other via a first connecting fluid channel 40P. The first inlet port 110S and the first outlet port 112S of the S-system are connected to each other via a first connecting fluid channel 40S. Shut-off valves 41 are provided in the first connecting fluid channels 40.The shut-off valves 41 are normally open proportional control valves (electromagnetic valves). The shut-off valve 41P is located in the first connecting fluid channel 40P, and the shut-off valve 41S is located in the first connecting fluid channel 40S. Each of the first connecting fluid channels 40 branches through the shut-off valve 41 into an upstream fluid channel 40U on the master cylinder side 2 and a downstream fluid channel 40L on the wheel cylinder side 3.

[0015] A hydraulic pressure sensor 26 is provided in the upstream fluid channel 40U of the S-system. The hydraulic pressure sensor 26 detects the hydraulic pressure of the main cylinder. A simulator fluid channel 51 branches off from the upstream fluid channel 40U of the P-system. The simulator fluid channel 51 is connected to the positive pressure chamber 35 of the lifting simulator 13. The downstream fluid channel 40L (40P) of the P-system and the downstream fluid channel 40L (40S) of the S-system are connected to each other via communication fluid channels 44. The communication fluid channels 44 comprise a communication fluid channel 44P, which is connected to the downstream fluid channel 40L (40P) of the P-system, and a communication fluid channel 44S, which is connected to the downstream fluid channel 40L (40S) of the S-system. Communication valves 46 are provided in the communication fluid channels 44. The communication valves 46 are normally closed ON / OFF valves (electromagnetic valves).A hydraulic pressure sensor 27 is provided at a connection section between the communication fluid channel 44P and the communication fluid channel 44S. The hydraulic pressure sensor 27 detects an outlet pressure of a first pump 24.

[0016] The first hydraulic pressure unit 105 comprises the first pump 24 and a motor 25, which serves as its drive source. The first pump 24 is a piston pump. The motor 25 is, for example, a brushless motor. The flow rate of the first pump 24 can be adjusted by controlling the rotational speed of the motor 25. An inlet fluid channel 42 is connected to the inlet side of the first pump 24. The inlet fluid channel 42 is connected to the internal fluid pool chamber 43. The internal fluid pool chamber 43 is connected to the suction hose 21 at the suction opening 111 and receives the supply of brake fluid from the reservoir 9.The internal fluid pool chamber 43 has a predetermined volume and enables a continuous supply of brake fluid to the first pump 24 due to the brake fluid contained in the internal fluid pool chamber 43, even if, for example, a leakage fault has occurred in the suction hose 21 and no supply of brake fluid from the reservoir 9 is possible. The outlet side of the first pump 24 is connected to the connecting fluid channels 44.

[0017] The connecting fluid channels 44 are connected to a pressure-reducing fluid channel 47. The pressure-reducing fluid channel 47 is further connected to a return fluid channel 17. The return fluid channel 17 is a low-pressure section open to atmospheric pressure and connected to the internal fluid receiving chamber 43. A pressure control valve (a changeover valve) 48 is provided in the pressure-reducing fluid channel 47. The pressure control valve 48 is a normally open proportional control valve (electromagnetic valve). A fluid channel 28 connects the back pressure chamber 36 of the stroke simulator 13 and the first connecting fluid channel 40P (40L). A one-way valve 29 is provided in the fluid channel 28. The one-way valve 29 allows brake fluid to flow from the side of the counter-pressure chamber 36 to the side of the first connecting fluid channel 40P and prevents brake fluid from flowing in the opposite direction in the fluid channel 28.A fluid channel 31 connects the counter-pressure chamber 36 of the lifting simulator 13 and the return fluid channel 17. A lifting simulator OFF valve (a control valve) 34 is a normally closed ON / OFF valve provided in the fluid channel 31.

[0018] The first control unit 18 is an electronic control unit (ECU) that controls the first hydraulic pressure unit 105. The first control unit 18 is connected to the stroke sensor 12 via a special electrical cable (a power supply line, a ground line, or a signal line). The first control unit 18 calculates a target hydraulic pressure of the wheel cylinder based on the pedal stroke detected by the stroke sensor 12. For example, the relationship between the pedal stroke and the target hydraulic pressure of the wheel cylinder is pre-stored in a table, and the target hydraulic pressure of the wheel cylinder is determined according to the value detected by the stroke sensor 12. In addition, the first control unit 18 controls each of the solenoid valves and the motor 25 of the first hydraulic unit 105.For example, the first control unit 18 actuates the shut-off valves 41 in the valve closing direction and also actuates the lift simulator OFF valve 34 in the valve opening direction in order to block the flow of brake fluid in the master cylinder 2 according to the driver's brake actuation and to direct the brake fluid in the master cylinder 2 to the lift simulator 13, thereby generating a pedal stroke and a corresponding reaction force.

[0019] If, however, the generation of the target wheel cylinder hydraulic pressure is detected in accordance with the driver's brake application, the first control unit 18 drives the motor 25 to actuate the first pump 24 and simultaneously actuates the communication valves 46 in the opening direction and the pressure control valve 48 in the closing direction, causing the brake fluid expelled from the first pump 24 to flow from the connecting fluid channels 44 to the first connecting fluid channels 40. Since the shut-off valves 41 are closed at this point, the brake fluid flows into the unit connecting pipes 23 and, via the second hydraulic pressure unit 106, into each of the wheel cylinders 3, thereby generating the wheel cylinder hydraulic pressure. In this case, the connecting fluid channels 44 are in a connected state and form a hydraulic pressure circuit.Therefore, all wheel cylinders 3 have the same wheel cylinder hydraulic pressure, so that the wheel cylinder hydraulic pressure can be measured with the hydraulic pressure sensor 27.

[0020] The first control unit 18 controls the flow rate of brake fluid into the wheel cylinders 3 based on the rotational frequency of the motor 25, according to the hydraulic pressure feedback from the hydraulic pressure sensor 27. Simultaneously, the first control unit 18 adjusts the outflow rate by adjusting the opening of the pressure control valve 48 so that the brake fluid flows to the pressure reducing fluid channel 47. Therefore, the first control unit 18 can arbitrarily increase / decrease the amount of brake fluid supplied to the wheel cylinders 3, thus implementing wheel cylinder hydraulic pressure control aimed at generating a wheel cylinder hydraulic pressure that corresponds to the target wheel cylinder hydraulic pressure.

[0021] Furthermore, the first connecting fluid channels 40, which connect the master cylinder 2 and the wheel cylinders 3, each branch through the shut-off valve 41 into the upstream fluid channel 40U and the downstream fluid channel 40L. This configuration enables a so-called brake-by-wire state, in which no change occurs at the brake pedal 4, even with any setting of the wheel cylinder hydraulic pressure. The target hydraulic pressure of the wheel cylinder does not depend solely on the pedal travel. A request for autonomous braking (e.g., collision mitigation braking and adaptive cruise control) is issued by the vehicle system, or a request for friction brake control is issued by a regenerative cooperative braking function. A communication unit is provided to input these requests via the vehicle and a CAN (Control Area Network).

[0022] The second unit 7 is a unit in which the second hydraulic pressure unit 106 and a second control unit (a second control device) 19 are integrally provided. The second hydraulic pressure unit 106 can control the wheel cylinder hydraulic pressures in the P-system and the S-system independently of each other using the brake fluid flowing in from the unit connecting pipes 23. In addition, the second hydraulic pressure unit 106 can control the brake hydraulic pressure in each of the wheel cylinders 3a to 3d independently of each other. The second hydraulic pressure unit 106 includes second inlet ports 200 and second outlet ports 201. The second inlet port 200P of the P-system is connected to the unit connecting pipe 23P. The second inlet port 200S of the S-system is connected to the unit connecting pipe 23S. The second outlet ports 201 are connected to the wheel cylinder lines 22.The second input port 200P of the P-system is connected to a second interconnection fluid channel 211P. The second input port 200S of the S-system is connected to a second interconnection fluid channel 211S. The second interconnection fluid channel 211P of the P-system branches into a second interconnection fluid channel 211a and a second interconnection fluid channel 211d and is connected to the second output ports 201a and 201d. The second interconnection fluid channel 211S of the S-system branches into second interconnection fluid channels 211b and 211c and is connected to the second output ports 201b and 201c.

[0023] Pressure booster valves 230a to 230d are provided in each of the second connecting fluid channels 211a to 211d. These pressure booster valves are normally open proportional control valves (electromagnetic valves). Pressure reducing fluid channels 231a to 231d are connected to the second outlet ports 201a to 201d of the second connecting fluid channels 211a to 211d with respect to the pressure booster valves 230a to 230d. The pressure reducing fluid channels 231a to 231d are interconnected at pressure reducing fluid channel 231. Pressure reducing valves 232 are provided in each of the pressure reducing fluid channels 231a to 231d. The pressure reducing valves 232 are normally closed on / off valves (electromagnetic valves). A hydraulic pressure sensor 208 is provided in the second connecting fluid channel 211P of the P-system. The hydraulic pressure sensor 208 detects a hydraulic pressure at this position.

[0024] The second hydraulic pressure unit 106 comprises a second pump 214P of the P-system and a second pump 214S of the S-system, as well as a motor 215 that serves as the drive source for these. Both the second pump 214P and the second pump 214S are piston pumps. The motor 215 is, for example, a brushless motor. The flow rates of the second pump 214P and the second pump 214S can be adjusted by controlling the rotational speed of the motor 215. Suction fluid channels 216 are connected to the suction sides of the second pumps 214. The suction fluid channels 216 are connected to the pressure reducing fluid channel 231. The outlet side of the second pump 214P of the P-system is connected to an outlet fluid channel 209P. The outlet side of the second pump 214S of the S-system is connected to an outlet fluid channel 209S. The outlet fluid channel 209P of the P-system is connected to the second connecting fluid channel 211P.The outlet fluid channel 209S of the S-system is connected to the second connecting fluid channel 211S.

[0025] The second control unit 19 is an electronic control unit (ECU) that controls the second hydraulic pressure unit 106 and the shut-off valves 41 of the first hydraulic pressure unit 105. The second control unit 19 calculates a vehicle behavior state based on values ​​detected by a wheel speed sensor 300, a yaw rate sensor 301, and the like. The wheel speed sensor 300 is located on each of the wheels FL to RR and detects the rotational speed of each wheel. The yaw rate sensor 301 detects the longitudinal acceleration and yaw rate of the vehicle. For example, the second control unit 19 performs ABS control if a currently braked wheel shows a tendency to lock up and performs ESC control if the vehicle is in a lateral slip state as a result of the calculated vehicle behavior state.For example, if the ESC control detects a side slip condition based on the vehicle behavior condition intended for the control, the second control unit 19 calculates a target wheel cylinder hydraulic pressure to correct the side slip and actuates the second hydraulic pressure unit 106 so that the wheel cylinder hydraulic pressure corresponds to the target wheel cylinder hydraulic pressure.

[0026] The second control unit 19 includes a communication unit for outputting the calculated vehicle behavior state to the vehicle side via the CAN bus. The first control unit 18 and the second control unit 19 send and receive data via the CAN bus. The second control unit 19 does not include a hydraulic pressure sensor that actually measures the wheel cylinder hydraulic pressure and should therefore estimate the wheel cylinder hydraulic pressure so that it can follow the target wheel cylinder hydraulic pressure in the ABS or ECS control unit. An example of this is now described.

[0027] For example, if the first hydraulic unit 105 is not in operation, e.g., if the driver is not pressing the brake pedal 4, the hydraulic pressures at the second input ports 200 are zero. Assuming that, starting from this state, the ESC control is performed based on the result of the vehicle behavior state calculation, and the target hydraulic pressure of the wheel cylinder is generated at the front left wheel FL to decelerate the vehicle, while the target hydraulic pressure of the wheel cylinder at the other wheels FR, RL, and RR is set to zero.

[0028] The second control unit 19 drives the motor 215 to actuate the second pumps 214P and 214S of both systems and simultaneously actuates the shut-off valve 41P of the first hydraulic pressure unit in the valve closing direction. The shut-off valve 41P can be controlled by the first control unit 18. The following description continues to focus on the P-system. The brake fluid is supplied to the second pump 214P via the suction hose 21, the pressure reducing fluid channel 231, and the inlet fluid channel 216P, and is discharged from the second pump 214P to the outlet fluid channel 209P.Since the shut-off valve 41P is in the closed state, the brake fluid flows from the second connecting fluid channel 211 to the second connecting fluid channel 211a of the front left wheel FL and to the second connecting fluid channel 211d of the rear right wheel RR and can increase the pressure in the wheel cylinder 3a of the front left wheel FL and in the wheel cylinder 3d of the rear right wheel RR.

[0029] At this point, brake fluid can only be supplied to the front left wheel FL to increase the pressure only in the wheel cylinder 3a of the front left wheel FL by actuating the pressure booster valve 230a towards opening and the pressure booster valve 230d towards closing. The wheel cylinder hydraulic pressures at this point can be estimated based on the quantities of brake fluid transferred to the wheel cylinder 3a of the front left wheel FL and the wheel cylinder 3d of the rear right wheel RR. The quantities of brake fluid transferred to the wheel cylinder 3a of the front left wheel FL and the wheel cylinder 3d of the rear right wheel RR can be estimated by calculating the pump delivery rate based on the rotational frequency of the motor 215 and the flow rates based on the open / closed states of the pressure booster valves 230, and calculating the cumulative quantities.The brake fluid quantity and the wheel cylinder hydraulic pressure are interrelated, and the brake fluid quantity can also be converted into hydraulic pressure. Therefore, the wheel cylinder hydraulic pressure can be estimated.

[0030] Next, with respect to the S-system (the front right wheel FR and the rear left wheel RL), the shut-off valve 41S is in the open position. Therefore, the brake fluid discharged from the second pump 214S into the outlet fluid channel 209S is returned to the master cylinder 2 via the second connecting fluid channel 211S and the first connecting fluid channel 40P. Consequently, no brake fluid flows into the wheel cylinder 3b of the front right wheel FR and the wheel cylinder 3c of the rear left wheel RL, allowing these wheel cylinders 3b and 3c to have zero pressure. In this way, the hydraulic pressure in each of the wheel cylinders 3 can be independently regulated to any desired pressure by controlling the shut-off valves 41 of the first hydraulic pressure unit 105, the second pumps 214 of the second hydraulic pressure unit 106, and each of the solenoid valves.In the brake control device 1 according to the first embodiment, the master cylinder tubes 10, the first connecting fluid channels 40, the unit connecting tubes 23, the second connecting fluid channels 211 and the wheel cylinder tubes 22 form a fluid channel that connects the master cylinder 2 and the wheel cylinders 3.

[0031] Next, the operation of the brake control device 1 according to the first embodiment will be described. (Normal brake control)

[0032] Normal brake control refers to a brake control system that generates appropriate deceleration according to the pedal travel produced by the driver when applying the brakes. In normal brake control, the brake control device 1 performs a boost control that assists the brake application by generating brake hydraulic pressure that supplements the driver's braking force. Normal brake control is implemented by the operation of the first hydraulic pressure unit 105. The first control unit 18 converts the signal output by the stroke sensor 12 into the pedal travel and calculates the target wheel cylinder hydraulic pressure according to the pedal travel.The first control unit 18 implements the wheel cylinder hydraulic pressure control by actuating each of the electromagnetic valves and the motor 25 of the first hydraulic pressure unit 105 according to the target wheel cylinder hydraulic pressure and using the value detected by the hydraulic pressure sensor 27 for feedback. Simultaneously, the lift simulator 13 is actuated, generating a natural pedal feel so that the driver experiences a comfortable braking sensation. (Autonomous brake control)

[0033] Autonomous brake control refers to a brake control system that generates deceleration in response to a request from the vehicle system, without the driver initiating braking. Autonomous brake control is implemented through the operation of the first hydraulic pressure unit 105. The first control unit 18 calculates the setpoint for the wheel cylinder hydraulic pressure to establish a setpoint for the autonomous brake input via CAN. The setpoint for the autonomous brake can be any physical quantity related to braking, such as vehicle acceleration or deceleration. The first control unit 18 implements the wheel cylinder hydraulic pressure control by actuating each of the electromagnetic valves and the motor 25 of the first hydraulic pressure unit 105 according to the setpoint wheel cylinder hydraulic pressure and using the value detected by the hydraulic pressure sensor 27 for feedback. (Vehicle stability control)

[0034] Vehicle stability control refers to brake control, which aims to stabilize the vehicle by applying braking force independently to each of the wheels FL to RR. It is a function of a commonly used electronic stability control (ESC) system such as ABS (Anti-lock Braking System), TCS (Traction Control System), and LDP (Lane Departure Warning System). Vehicle stability control is achieved through the operation of the second hydraulic pressure unit 106. The second control unit 19 estimates the vehicle's condition based on the speed of each wheel, the longitudinal acceleration of the body, the lateral acceleration, the yaw rate, the steering angle, the engine torque, and / or similar factors, and controls the hydraulic pressure of each wheel cylinder independently. (Backup control)

[0035] The backup control refers to a control system in which the second unit 7 takes over brake control if a fault occurs in the first unit 6 and normal or autonomous brake control is no longer possible. A failure of the first unit 6 is primarily expected to be a failure that renders control impossible due to a malfunction of the electronic system, such as a short circuit in the valve solenoid, a malfunction of the hydraulic pressure sensor 26 or 27, a malfunction of the motor drive function in the first hydraulic unit 105, or a malfunction of the calculation function in the first control unit 18. Furthermore, a mechanical fault, such as a brake fluid leak in the first hydraulic pressure unit 105, is also to be expected. The first control unit 18 includes a unit that detects the fault described above in the first unit 6 and takes a safety measure, such as...The system transitions to a fallback mode or interrupts operation due to a failsafe when a fault is detected. If a fault is detected in the first unit 6, the first control unit 18 transmits this fault information to the second control unit 19 via CAN. Furthermore, the first control unit 18 deactivates the first hydraulic pressure unit 105 by interrupting the power supply to all solenoid valves and the motor 25 of the first hydraulic pressure unit 105.

[0036] The second hydraulic pressure unit in the conventional brake control device described in PTL 1 is then configured similarly to the units used in common electronic stability control (ESC) systems and comprises an exhaust valve and an inlet valve. The exhaust valve is a normally open proportional control valve (electromagnetic valve) located upstream of an exhaust fluid channel, which is connected to a pump outlet in a second connecting fluid channel that links the first hydraulic pressure unit and the wheel cylinders. The inlet valve is a normally closed proportional control valve (electromagnetic valve) located in a fluid channel branching off from the upstream side of the exhaust valve and connecting to a pump inlet in the connecting fluid channel.

[0037] The conventional brake control device described in PTL 1 can continue the ESC control or similar by actuating the inlet and outlet valves and supplying and discharging brake fluid into the second pump if a fault occurs in the first control device that controls the first hydraulic pressure unit. However, it has the problem that many electromagnetic valves are required, leading to increased costs. Another problem is that the inlet valve has a small cross-section of the flow channel compared to the pipe and therefore acts as a throttle, increasing the suction resistance of the second pump and limiting the pump's delivery rate, resulting in reduced performance when increasing the pressure in the wheel cylinder.

[0038] On the other hand, in the brake control device 1 according to the first embodiment, the shut-off valve 41 of the first hydraulic pressure unit 105 is controlled by both the first control unit 18 and the second control unit 19. This allows the second control unit 19 to continue ESC control or the like by controlling the shut-off valve 41 in the event of a failure of the first control unit 18. This eliminates the need for an inlet valve and an outlet valve in the second hydraulic pressure unit 106 and reduces the number of solenoid valves by four compared to the conventional brake control device described in PTL 1, thereby achieving a cost reduction.

[0039] Furthermore, the second hydraulic pressure unit 106 according to the first embodiment comprises the pressure reducing valve 232, which is connected to the reservoir 9 in conjunction with the master cylinder 2, the second pump 214, which is suitable for drawing brake fluid from the reservoir 9, and the pressure increasing valve 230, which is connected to the outlet port of the second pump 214. This allows the second pump 214 to draw brake fluid from the reservoir 9 without the intervention of an electromagnetic valve, thereby suppressing an increase in the suction resistance of the second pump 214. This allows the pump's delivery rate to be maintained and prevents a reduction in power required to increase the pressure in the wheel cylinder 3, without leading to an increase in pump size or power consumption. [Second embodiment]

[0040] A second embodiment has a similar basic configuration to the first embodiment and is therefore only described with regard to the differences from the first embodiment. Fig. Figure 3 shows the configuration of a first unit 501 of a brake control device 500 according to the second embodiment. Fig. Figure 4 shows the configuration of an electric piston 502 of the brake control device 500 according to the second embodiment. The brake control device 400 according to the second embodiment comprises the first unit 501, the second unit 6, and the electric piston 502. The configuration of the second unit 6 according to the second embodiment is similar to that of the first embodiment; therefore, its illustration and description are omitted here. Furthermore, the first unit 501 is described, whereby sections with the same function as in the first embodiment are assigned the same reference numerals, and their descriptions are omitted.

[0041] The first unit 501 is a unit in which the main cylinder 2, the reservoir 9, the lifting simulator 13, a first hydraulic pressure unit (a first hydraulic pressure generating device) 503, and the first control unit 18 are integrally provided. The main cylinder 2, the lifting simulator 13, the first hydraulic pressure unit 503, and the first control unit 18 are provided in the same housing 503. The first unit 501 includes third inlet ports 505. The third inlet port 505P of the P-system is connected to an outlet fluid channel 504P of the P-system. The outlet fluid channel 504P is connected to the downstream fluid channel 40L of the first connecting channel 40 of the P-system. The third inlet port 505S of the S-system is connected to an outlet fluid channel 504S of the S-system. The outlet fluid channel 504S is connected to the downstream fluid channel 40L of the first connecting fluid channel 40 of the S-system.The third inlet port 505P of the P-system is connected to a unit connecting pipe 506P. The third inlet port 505S of the S-system is connected to a unit line 506S.

[0042] The electric piston 502 is actuated by a motor 507 to generate brake hydraulic pressure. The electric piston 502 includes a master cylinder 508, which is configured similarly to a tandem master cylinder. The master cylinder 508 comprises a primary piston 509P and a secondary piston 509S, which are arranged in series within a master cylinder housing 513. The primary piston 509P is connected to a pushrod 510. The secondary piston 509S is configured as a free piston. The pushrod 510 has an external threaded section 510a, which engages with an internal threaded section 511a formed on the inner circumference of a nut 511. An external threaded section 511b, formed on the outer circumference of the nut 511, engages with a pinion 507b, which is mounted on a motor drive shaft 507a.The pinion 507b has a smaller diameter than the nut 511, and the pinion 507b and the nut 511 act as a reduction gear, which transmits a rotation of the motor drive shaft 507a to the nut 511, thereby slowing its rotational speed.

[0043] The nut 511 is rotatably mounted relative to the master cylinder housing 513 by two bearings 512a and 512b. The rotation of the motor drive shaft 507a is transmitted by the pinion 507b to the nut 511, and the pushrod 510 moves axially in accordance with the rotation of the nut 511. The nut 511 and the pushrod 510 function as a ball recirculation mechanism. The brake fluid is fed from the reservoir 9 via the suction hose 21 into a primary chamber 514P and a secondary chamber 514S of the master cylinder 508. This generates a brake hydraulic pressure in the primary chamber 514P and the secondary chamber 514S, corresponding to the movement of the pushrod 510, and directs it via the unit connecting pipes 506P and 506S and the outlet fluid channels 504P and 504S to the first connecting fluid channels 40P and 40S. The motor 507 is controlled by the first control unit 18.The first control unit 18 drives the motor 507 in rotation according to the target hydraulic pressure of the wheel cylinder.

[0044] A simulator valve (a control valve) 52 is provided in the simulator fluid channel 51. The simulator valve 52 is a normally closed on / off valve (electromagnetic valve). The simulator valve 52 is controlled by both the first control unit 18 and the second control unit 19. For example, a pedal stroke and a corresponding reaction force can be generated by actuating the shut-off valves 41 in the valve closing direction to block the flow of brake fluid in the master cylinder 2 in accordance with the driver's brake application, and by also actuating the simulator valve 52 in the opening direction to direct the brake fluid in the master cylinder 2 to the stroke simulator 13.In the second embodiment, the simulator valve 52 can be controlled by both the first control unit 18 and the second control unit 19, so that the opening / closing of the simulator valve 52 can be controlled by the second control unit 19 if a fault has occurred in the first control unit 18. This allows a natural pedal feel to be generated by actuating the stroke simulator 13, even if a fault has occurred in the first control unit 18 during normal brake control. In the brake control device 500 according to the second embodiment, the first connecting fluid channels 40, the unit connecting tubes 23, the second connecting fluid channels 211, and the wheel cylinder tubes 22 form a fluid channel that connects the master cylinder 2 and the wheel cylinders 3. [Other embodiments]

[0045] Following the description of the embodiments for implementing the present invention, the specific configuration of the present invention is not limited to the configurations of the embodiments, and the present invention also includes any design modifications and the like that are made within a scope that does not deviate from the spirit of the present invention, if any. In the first embodiment, the simulator outlet valve 34 can be configured to be controlled by both the first control unit 18 and the second control unit 19. The second embodiment has been described by way of example, in which the electric piston is used as the pressure generation source; however, a plunger pump can also be used.

[0046] The present invention is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above have been described in detail to facilitate a better understanding of the present invention, and the present invention is not necessarily limited to the configuration that includes all the described features. Furthermore, part of the configuration of one embodiment can be replaced by the configuration of another embodiment. In addition, some embodiments can also be implemented with a configuration of another embodiment added to the configuration of this embodiment. Moreover, each embodiment can also be implemented with a different configuration that adds to, deletes, or replaces part of the configuration of this embodiment.

[0047] The present application claims priority under the Paris Convention from Japanese patent application No. 2023-114867, filed on July 13, 2023. The entire disclosure of Japanese patent application No. 2023-114867, filed on July 13, 2023, including the description, claims, drawings, and abstract, is hereby incorporated by reference in its entirety. REFERENCE MARK LIST 1 Brake control device 2 main cylinders 3 wheel cylinders 13 Hub Simulator 105 first hydraulic pressure unit (first hydraulic pressure generating device) 106 second hydraulic pressure unit (second hydraulic pressure generating device) 108 first control unit (first control device) 109 second control unit (second control device) 41 Shut-off valve 52 Simulator valve 214 second pump 230 Pressure boosting valve 232 Pressure reducing valve QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2016-120292

[0003] JP 2023-114867

[0047]

Claims

[1] Brake control device comprising the following: a fluid channel containing a master cylinder configured to generate a brake hydraulic pressure corresponding to a brake actuation, and a wheel cylinder configured to exert a braking force on a wheel according to the brake hydraulic pressure, connects; a first hydraulic pressure generating device which is provided in the fluid channel and is configured to generate a brake hydraulic pressure independently of the brake actuation; a second hydraulic pressure generating device, which is provided in the fluid channel closer to the wheel cylinder in relation to the first hydraulic pressure generating device and is set up to generate brake hydraulic pressure independently of brake actuation; a shut-off valve that is provided and configured between the main cylinder and the first hydraulic pressure generating device in the fluid channel, terminating the connection between the main cylinder and the first to block hydraulic pressure generating device; a first control device configured to control the first hydraulic pressure generating device; and a second control device configured to control the second hydraulic pressure generating device, where the shut-off valve is controlled by both the first control device and the second control device. [2] Brake control device according to claim 1, wherein the second hydraulic pressure generating device a pressure reducing valve connected to a reservoir in conjunction with the main cylinder, a pump designed to draw brake fluid from a reservoir, and includes a pressure boosting valve connected to an outlet of the pump. [3] Brake control device according to claim 1 or 2, wherein the first hydraulic pressure generating device a lifting simulator connected to the fluid channel, and a control valve configured to control the connection between the fluid channel and the lifting simulator, the control valve is controlled by both the first control device and the second control device.

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