Braking device

Abstract

This braking device 100 comprises a first supply source 50A, a second supply source 50B, a switching unit 40, a first controller 61, and a second controller 62. When having determined that there is a sign of abnormality in a counterpart controller, the controllers 61, 62 execute connection control for adjusting braking pressures of a first wheel cylinder 211 and a second wheel cylinder 212 by operating the supply source to be controlled itself after setting a state of the switching unit 40 to a communicating state.

Description

Brake device

[0001] The present invention relates to a brake device that applies braking force to a vehicle by adjusting the braking pressures of a first wheel cylinder and a second wheel cylinder.

[0002] Patent Document 1 discloses a brake device comprising a first supply source connected to a first wheel cylinder via a first fluid passage, and a second supply source connected to a second wheel cylinder via a second fluid passage. The brake device further comprises a communication passage connecting the first fluid passage and the second fluid passage, and a switching valve installed in the communication passage.

[0003] When a braking request is generated in a situation where all of the plurality of supply sources operate normally, the communication between the first fluid passage and the second fluid passage is blocked by closing the switching valve. In this state, brake fluid is supplied from the first supply source via the first fluid passage, whereby the first braking pressure, which is the braking pressure of the first wheel cylinder, is adjusted. Further, brake fluid is supplied from the second supply source via the second fluid passage, whereby the second braking pressure, which is the braking pressure of the second wheel cylinder, is adjusted. Such braking control is referred to as "blocking control".

[0004] On the other hand, when an abnormality occurs only in one of the plurality of supply sources, the first fluid passage and the second fluid passage are brought into communication with each other by opening the switching valve. In this state, the other supply source is activated. In this case, brake fluid is supplied from the other supply source to the plurality of wheel cylinders. That is, the first braking pressure and the second braking pressure are adjusted by the operation of one supply source. Such braking control is referred to as "connection control".

[0005] Japanese Patent Application Laid-Open No. 2022-27055

[0006] For example, consider a braking system that includes a first controller for controlling a first power source and a second controller for controlling a second power source. In this case, while the first and second braking pressures are being adjusted by shut-off control, a malfunction may occur in only one of the two controllers, for example, the first controller. In this case, the first controller will be unable to control the first power source, causing the first braking pressure to decrease. Therefore, when the second controller can determine that a malfunction has occurred in the first controller, it opens the switching valve and switches the control from shut-off control to connection control. The second controller then adjusts the first and second braking pressures by operating the second power source.

[0007] As described above, there is a time lag between the moment an abnormality actually occurs in the first controller and the second controller being able to confirm that an abnormality has occurred in the first controller. In other words, there is a time lag between the time an abnormality occurs in the first controller and control of the first braking pressure becomes impossible, and the time when connection control by the second controller begins. If this time lag is long, there is a risk that the period during which there is a discrepancy between the first and second braking pressures will be prolonged.

[0008] A braking device for solving the above problems is applied to a vehicle comprising a first wheel and a second wheel arranged at different positions in the vehicle width direction, a first wheel cylinder corresponding to the first wheel, and a second wheel cylinder corresponding to the second wheel. The braking device comprises a first fluid passage which is a brake fluid passage connected to the first wheel cylinder, a second fluid passage which is a brake fluid passage connected to the second wheel cylinder, a first supply source connected to the first fluid passage and discharging brake fluid into the first fluid passage, a second supply source connected to the second fluid passage and discharging brake fluid into the second fluid passage, a switching unit that can switch between a communication state in which the first fluid passage and the second fluid passage are in communication and a disconnection state in which communication between the first fluid passage and the second fluid passage is blocked, a first controller that controls the first supply source and the switching unit, and a second controller which is mutually able to acquire information with the first controller and controls the second supply source and the switching unit. Each of the multiple controllers is configured to determine that an abnormality has occurred in the other controller if it is unable to obtain information from the other controller, and the duration of the period during which information cannot be obtained reaches the abnormality determination time. If the duration has not reached the abnormality determination time, it determines that there is a sign of an abnormality in the other controller. In a situation where a shut-off control is being performed in which the communication between the first fluid passage and the second fluid passage is shut off by the control of the switching unit by at least one of the multiple controllers, and the first braking pressure, which is the braking pressure of the first wheel cylinder, is adjusted by the operation of the first supply source, and the second braking pressure, which is the braking pressure of the second wheel cylinder, is adjusted by the operation of the second supply source, if one of the multiple controllers determines that there is a sign of an abnormality in the other controller, that one controller controls the switching unit to connect the first fluid passage and the second fluid passage, and then performs connection control in which that one controller operates the supply source corresponding to that one of the multiple supply sources to adjust the first and second braking pressures.

[0009] The above-described braking system can ensure the stability of vehicle behavior when an abnormality occurs in the first controller or the second controller while the vehicle is decelerating due to the application of braking force.

[0010] Figure 1 is a schematic diagram showing a vehicle equipped with the braking system of the embodiment. Figure 2 is a flowchart showing the processing flow when determining whether or not an abnormality has occurred in the controller of the braking system of Figure 1. Figure 3 is a flowchart showing the processing flow when adjusting the first braking pressure and the second braking pressure in accordance with the braking request of the braking system of Figure 1. Figures 4(a) to 4(c) are timing charts when an abnormality occurs in only one of the first controller and the second controller shown in Figure 1. Figure 5 is a schematic diagram showing a vehicle equipped with a modified braking system.

[0011] An embodiment of the braking device will be described with reference to Figures 1 to 4. <Overall Vehicle Configuration> Figure 1 shows a vehicle 10 equipped with a braking device 100. The vehicle 10 comprises a plurality of wheels, a plurality of friction brakes 20 provided for each of the plurality of wheels, and a plurality of sensors. The plurality of wheels include a first wheel 11 and a second wheel 12. For example, the first wheel 11 and the second wheel 12 are the front wheels of the vehicle 10, which are positioned at different locations from each other in the vehicle width direction.

[0012] Each of the multiple friction brakes 20 comprises a wheel cylinder, a rotating body 22, and a friction part 23. The hydraulic pressure in the wheel cylinder is the braking pressure. The rotating body 22 rotates integrally with the corresponding wheels 11 and 12. The friction brake 20 can apply braking force to the corresponding wheels 11 and 12 by pressing the friction part 23 against the rotating body 22. The force pressing the friction part 23 against the rotating body 22 increases as the braking pressure of the wheel cylinder increases. In other words, the friction brake 20 can apply a greater braking force to the corresponding wheels 11 and 12 as the braking pressure of the wheel cylinder increases.

[0013] Hereafter, the wheel cylinder corresponding to the first wheel 11 will be referred to as the "first wheel cylinder 211". The wheel cylinder corresponding to the second wheel 12 will be referred to as the "second wheel cylinder 212".

[0014] Multiple sensors include, for example, a brake sensor 16, a wheel speed sensor 17, a yaw rate sensor 18, and an acceleration sensor 19. The brake sensor 16 detects operation-related information, which is information related to the driver's operation of the brake pedal. An example of the brake sensor 16 is a stroke sensor that detects the amount of operation of the driver's brake pedal as operation-related information. The amount of operation based on the detection signal of the brake sensor 16 is referred to as "braking operation amount Ba".

[0015] A wheel speed sensor 17 is provided for each of the multiple wheels 11 and 12. Each of the multiple wheel speed sensors 17 detects the rotational speed of the corresponding wheel 11 or 12. The rotational speed of the wheels 11 and 12 based on the detection signals of the wheel speed sensors 17 is referred to as "wheel speed VW". The vehicle speed VS of the vehicle 10 is calculated based on the wheel speeds VW of the multiple wheels 11 and 12.

[0016] The yaw rate sensor 18 detects the yaw rate of the vehicle 10. The yaw rate of the vehicle 10 based on the detection signal from the yaw rate sensor 18 is denoted as "yaw rate YR". The acceleration sensor 19 detects the longitudinal acceleration and lateral acceleration of the vehicle 10. The longitudinal acceleration of the vehicle 10 based on the detection signal from the acceleration sensor 19 is denoted as "longitudinal acceleration GX". The lateral acceleration of the vehicle 10 based on the detection signal from the acceleration sensor 19 is denoted as "lateral acceleration GY".

[0017] <Configuration of the braking system> The braking system 100 is configured to apply braking force to the vehicle 10 by adjusting the first braking pressure Pw1 and the second braking pressure Pw2. The braking system 100 includes a braking actuator 30, a control unit 60, and an integrated control device 80.

[0018] <Braking Actuator> The braking actuator 30 includes a reservoir 31, a first fluid passage 32, a second fluid passage 34, a switching unit 40, a reservoir shut-off unit 45, a first supply source 50A, and a second supply source 50B.

[0019] The reservoir 31 stores brake fluid and is open to the atmosphere. The first fluid passage 32 and the second fluid passage 34 are brake fluid passages through which brake fluid flows. The first fluid passage 32 is connected to the first wheel cylinder 211. The second fluid passage 34 is connected to the second wheel cylinder 212. A first hydraulic pressure sensor 33 is connected to the first fluid passage 32 to detect the brake fluid pressure in the first fluid passage 32. A second hydraulic pressure sensor 35 is connected to the second fluid passage 34 to detect the brake fluid pressure in the second fluid passage 34. Each of the first hydraulic pressure sensor 33 and the second hydraulic pressure sensor 35 outputs a detection signal to the control unit 60 according to the detection result. For example, the detection signal from the first hydraulic pressure sensor 33 is input to the second controller 62 of the control unit 60, which will be described later. The detection signal from the second hydraulic pressure sensor 35 is input to the first controller 61 of the control unit 60, which will be described later. Hereafter, the detected value of the first braking pressure Pw1 based on the detection signal of the first hydraulic pressure sensor 33 will be referred to as "first braking pressure detected value Pw1S". The detected value of the second braking pressure Pw2 based on the detection signal of the second hydraulic pressure sensor 35 will be referred to as "second braking pressure detected value Pw2S".

[0020] The switching unit 40 is configured to switch between a connected state, which connects the first fluid passage 32 and the second fluid passage 34, and a blocked state, which blocks the connection between the first fluid passage 32 and the second fluid passage 34. For example, the switching unit 40 has a connecting passage 41, a first system shut-off valve 42, and a second system shut-off valve 43. The connecting passage 41 is a brake fluid passage that connects the first fluid passage 32 and the second fluid passage 34. Of the two ends of the connecting passage 41, the first end is connected to the first fluid passage 32, and the second end is connected to the second fluid passage 34.

[0021] The first system shut-off valve 42 and the second system shut-off valve 43 are switching valves installed in the communication passage 41. Of the two system shut-off valves 42 and 43, the one located near the first hydraulic pressure sensor 33 is the first system shut-off valve 42, while the one located near the second hydraulic pressure sensor 35 is the second system shut-off valve 43. Each of the first system shut-off valve 42 and the second system shut-off valve 43 is a normally open solenoid valve. Therefore, when the power supply to the system shut-off valves 42 and 43 is stopped, the system shut-off valves 42 and 43 open. As a result, the first liquid passage 32 and the second liquid passage 34 communicate via the communication passage 41. On the other hand, when power is supplied to the system shut-off valves 42 and 43, the system shut-off valves 42 and 43 close. As a result, communication between the first liquid passage 32 and the second liquid passage 34 via the communication passage 41 is interrupted. Therefore, the state of the switching unit 40 when both of the multiple system shut-off valves 42 and 43 are open is the "communication state". On the other hand, the state of the switching unit 40 when all of the multiple system shut-off valves 42 and 43 are closed is the "shut-off state".

[0022] The reservoir shut-off section 45 includes an atmospheric vent passage 46, which is a brake fluid passage connecting the communication passage 41 and the reservoir 31, and a reservoir shut-off valve 47 installed in the atmospheric vent passage 46. The atmospheric vent passage 46 is connected to the portion of the communication passage 41 between the first system shut-off valve 42 and the second system shut-off valve 43. The reservoir shut-off valve 47 is a normally open solenoid valve. For example, the reservoir shut-off valve 47 has a first solenoid and a second solenoid. When power is supplied to at least one of the first solenoid and the second solenoid, the reservoir shut-off valve 47 is closed. This shuts off communication between the portion of the communication passage 41 between the first system shut-off valve 42 and the second system shut-off valve 43 and the reservoir 31. On the other hand, when the power supply to both the first solenoid and the second solenoid is stopped, the reservoir shut-off valve 47 is opened. As a result, the portion of the communication passage 41 between the first system shut-off valve 42 and the second system shut-off valve 43 is connected to the reservoir 31.

[0023] The first supply source 50A is connected to the first fluid passage 32 and discharges brake fluid into the first fluid passage 32. Therefore, the first supply source 50A can supply brake fluid to the first wheel cylinder 211 via the first fluid passage 32. The second supply source 50B is connected to the second fluid passage 34 and discharges brake fluid into the second fluid passage 34. Therefore, the second supply source 50B can supply brake fluid to the second wheel cylinder 212 via the second fluid passage 34.

[0024] Each of the first supply source 50A and the second supply source 50B has, for example, an electric cylinder 51. The electric cylinder 51 has a cylinder 52, a piston 53, an electric motor 54, and a conversion mechanism 55. The piston 53 is provided so as to be able to reciprocate within the cylinder 52. The conversion mechanism 55 converts the rotation of the output shaft of the electric motor 54 into the linear movement of the piston 53.

[0025] Inside the cylinder 52, a hydraulic chamber Re for storing brake fluid is partitioned by the peripheral wall of the cylinder 52 and the piston 53. The position of the piston 53 inside the cylinder 52 can be changed by driving the electric motor 54. Hereafter, the movement of the piston 53 when decreasing the volume of the hydraulic chamber Re will be described as "forward." The movement of the piston 53 when increasing the volume of the hydraulic chamber Re will be described as "reverse." Reverse is the movement of the piston 53 in the opposite direction to forward.

[0026] When the piston 53 moves forward due to the drive of the electric motor 54 of the first power source 50A, the brake fluid from the hydraulic chamber Re is discharged into the first fluid passage 32 via the output port 52p. As a result, brake fluid is supplied to the first wheel cylinder 211, and the first braking pressure Pw1 increases. When the piston 53 moves forward due to the drive of the electric motor 54 of the second power source 50B, the brake fluid from the hydraulic chamber Re is discharged into the second fluid passage 34 via the output port 52p. As a result, brake fluid is supplied to the second wheel cylinder 212, and the second braking pressure Pw2 increases.

[0027] On the other hand, when the piston 53 retracts due to the drive of the electric motor 54 of the first supply source 50A, the brake fluid in the first fluid passage 32 flows into the hydraulic chamber Re via the output port 52p. As a result, the brake fluid from the first wheel cylinder 211 flows out into the first fluid passage 32, and the first braking pressure Pw1 decreases. When the piston 53 retracts due to the drive of the electric motor 54 of the second supply source 50B, the brake fluid in the second fluid passage 34 flows into the hydraulic chamber Re via the output port 52p. As a result, the brake fluid from the second wheel cylinder 212 flows out into the second fluid passage 34, and the second braking pressure Pw2 decreases.

[0028] The electric motor 54 has a motor angle sensor 54s. The motor angle sensor 54s outputs a detection signal to the control unit 60 in accordance with the change in the rotation angle of the output shaft of the electric motor 54. Specifically, the motor angle sensor 54s of the first power source 50A outputs a detection signal to the first controller 61 of the control unit 60, which will be described later. The motor angle sensor 54s of the second power source 50B outputs a detection signal to the second controller 62 of the control unit 60, which will be described later. Hereafter, the rotation angle of the electric motor 54 based on the detection signal of the motor angle sensor 54s will be referred to as "motor rotation angle θmt".

[0029] When the motor rotation angle θmt increases due to the drive of the electric motor 54, the piston 53 moves forward. Conversely, when the motor rotation angle θmt decreases due to the drive of the electric motor 54, the piston 53 moves backward.

[0030] <Control Unit> The control unit 60 controls the switching unit 40, the reservoir shut-off unit 45, the first power source 50A, and the second power source 50B. For example, the control unit 60 includes a first controller 61 and a second controller 62 that can acquire information from each other. The first controller 61 is a processing circuit that controls the supply of power to the first solenoid of the first power source 50A, the first system shut-off valve 42, and the reservoir shut-off valve 47. The second controller 62 is a processing circuit that controls the supply of power to the second solenoid of the second power source 50B, the second system shut-off valve 43, and the reservoir shut-off valve 47. An example of a processing circuit is an electronic control device. In this case, each of the multiple controllers 61, 62 has a CPU 71 and a memory 72 that stores a control program executed by the CPU 71. Each of the multiple controllers 61, 62 controls its own controlled object by having the CPU 71 execute the control program in the memory 72.

[0031] As described above, the detection signal from the second hydraulic pressure sensor 35 is input to the first controller 61. Therefore, the first controller 61 can derive the second braking pressure detection value Pw2S. The first controller 61 also transmits the second braking pressure detection value Pw2S to the second controller 62 at predetermined communication cycles. The detection signal from the first hydraulic pressure sensor 33 is input to the second controller 62. Therefore, the second controller 62 can derive the first braking pressure detection value Pw1S. The second controller 62 also transmits the first braking pressure detection value Pw1S to the first controller 61 at predetermined communication cycles. Therefore, the multiple controllers 61 and 62 can acquire either the first braking pressure detection value Pw1S or the second braking pressure detection value Pw2S.

[0032] <Integrated Control Device> The integrated control device 80 is, for example, a processing circuit that comprehensively controls the braking of the vehicle 10. An example of a processing circuit is an electronic control device. In this case, the integrated control device 80 has a CPU and a memory that stores a control program executed by the CPU.

[0033] The integrated control unit 80 is configured to send and receive information and commands with the control unit 60 via the in-vehicle network 200. An example of the in-vehicle network 200 is a CAN bus. "CAN" is an abbreviation for "Controller Area Network". The integrated control unit 80 can exchange information with the first controller 61 and the second controller 62 via the in-vehicle network 200. In this respect, the integrated control unit 80 corresponds to the "third controller".

[0034] The integrated control unit 80 monitors whether it can communicate normally with the first controller 61 and the second controller 62. For example, the integrated control unit 80 sends a confirmation signal to the first controller 61 at predetermined communication intervals. When the first controller 61 receives the confirmation signal via the in-vehicle network 200, it sends a reply signal to the integrated control unit 80 via the in-vehicle network 200 indicating that it has received the confirmation signal. When the integrated control unit 80 receives the reply signal, it can determine that it can communicate normally with the first controller 61, that is, that it can exchange information with the first controller 61. On the other hand, if the integrated control unit 80 sends a confirmation signal to the first controller 61 but does not receive a reply signal, it can determine that there is an abnormality in communication with the first controller 61. When the integrated control unit 80 determines that there is an abnormality in communication with the first controller 61, it sends a message to the second controller 62 indicating that it cannot exchange information with the first controller 61.

[0035] The integrated control device 80 monitors whether it can communicate normally with the second controller 62 using the same method as described above. <Braking control by the control unit> The control unit 60 can perform disconnection control and connection control as braking control to adjust the first braking pressure Pw1 and the second braking pressure Pw2.

[0036] <Example of shut-off control> In shut-off control, the control unit 60 sets the state of the switching unit 40 to a shut-off state. For example, the first controller 61 closes the first system shut-off valve 42. The second controller 62 closes the second system shut-off valve 43. As a result, the control unit 60 can shut off communication between the first liquid passage 32 and the second liquid passage 34.

[0037] In this state, the first controller 61 of the control unit 60 derives a required braking force FbRq, which is the required value of the braking force for the vehicle 10. For example, when the driver of the vehicle 10 is operating the brake pedal, the first controller 61 sets the required braking force FbRq to be larger the larger the braking operation amount Ba is. If another onboard control device requests deceleration of the vehicle 10, the first controller 61 sets the required braking force FbRq to the braking force corresponding to the request of the other control device.

[0038] Next, the first controller 61 sets the first target braking pressure Pw1Tr and the second target braking pressure Pw2Tr based on the requested braking force FbRq. The first target braking pressure Pw1Tr is the target value for the first braking pressure Pw1. The second target braking pressure Pw2Tr is the target value for the second braking pressure Pw2. For example, the first controller 61 sets the first target braking pressure Pw1Tr and the second target braking pressure Pw2Tr. The first controller 61 then transmits information regarding the second target braking pressure Pw2Tr to the second controller 62.

[0039] Brakes used to decelerate or maintain the vehicle 10's stop are referred to as "service brakes." On the other hand, brake control used to control the vehicle 10's behavior is referred to as "vehicle behavior control." During service braking, the first target braking pressure Pw1Tr and the second target braking pressure Pw2Tr are set to equal values. Conversely, during vehicle behavior control, the first target braking pressure Pw1Tr and the second target braking pressure Pw2Tr are often set to different values. Examples of vehicle behavior control include anti-lock brake control, anti-skid control, traction control, and rollover prevention control.

[0040] The first controller 61 activates the first supply source 50A based on the first target braking pressure Pw1Tr. The second controller 62 activates the second supply source 50B based on the second target braking pressure Pw2Tr.

[0041] Here, in the electric cylinder 51, among the movable range of the piston 53, the rearmost end is the rearmost position. The amount of forward movement of the piston 53 from the rearmost position is the stroke amount of the piston 53. In the electric cylinder 51, there is a correspondence relationship between the stroke amount of the piston 53 and the consumption amount, which is the supply amount of brake fluid from the electric cylinder 51 to the wheel cylinders 211 and 212. There is also a correspondence relationship between the braking pressure of the wheel cylinders 211, 212 and said consumption amount. Furthermore, there is also a correspondence relationship between the stroke amount of the piston 53 and the motor rotation angle θmt. Therefore, it can be said that there is a correspondence relationship between the motor rotation angle θmt and the braking pressure.

[0042] Accordingly, the first controller 61 uses a map showing the correspondence relationship between the motor rotation angle θmt and the first braking pressure Pw1 to acquire the motor rotation angle corresponding to the first target braking pressure Pw1Tr, and sets said motor rotation angle as the target motor rotation angle θmt1Tr. Then, the first controller 61 operates the electric cylinder 51 of the first supply source 50A by executing feedback control that causes the motor rotation angle θmt of the electric motor 54 of the first supply source 50A to follow the target motor rotation angle θmt1Tr.

[0043] Similarly, the second controller 62 uses a map showing the correspondence relationship between the motor rotation angle θmt and the second braking pressure Pw2 to acquire the motor rotation angle corresponding to the second target braking pressure Pw2Tr, and sets said motor rotation angle as the target motor rotation angle θmt2Tr. Then, the second controller 62 operates the electric cylinder 51 of the second supply source 50B by executing feedback control that causes the motor rotation angle θmt of the electric motor 54 of the second supply source 50B to follow the target motor rotation angle θmt2Tr.

[0044] <Example of connection control> Connection control is executed, for example, when only one of the first supply source 50A and the second supply source 50B cannot operate. When an abnormality occurs in the controller that controls the supply source, or when a component of the supply source is damaged, the supply source becomes inoperable.

[0045] In connection control, the control unit 60 sets the state of the switching unit 40 to a connected state. For example, the first controller 61 opens the first system shut-off valve 42. The second controller 62 opens the second system shut-off valve 43. If a malfunction occurs in the first controller 61, the first controller 61 cannot control the first system shut-off valve 42, so the power supply to the first system shut-off valve 42 is stopped. As a result, the first system shut-off valve 42 opens. If a malfunction occurs in the second controller 62, the second controller 62 cannot control the second system shut-off valve 43, so the power supply to the second system shut-off valve 43 is stopped. As a result, the second system shut-off valve 43 opens. Therefore, if at least one of the multiple controllers 61, 62 is functioning normally, the control unit 60 can set the state of the switching unit 40 to a connected state.

[0046] Next, the control unit 60 sets the requested braking force FbRq. If the first controller 61 is functioning normally, the first controller 61 sets the requested braking force FbRq. If all of the multiple controllers 61 and 62 are functioning normally, but communication between the multiple controllers 61 and 62 is poor, the first controller 61 sets the requested braking force FbRq. On the other hand, if an abnormality occurs in the first controller 61, the second controller 62 sets the requested braking force FbRq. In connection control, among the multiple controllers 61 and 62, the controller that sets the requested braking force FbRq is referred to as the "main controller".

[0047] The main controller of the control unit 60 sets the target braking pressure PwTr at predetermined control cycles based on the requested braking force FbRq. The target braking pressure PwTr is a common target value for the first braking pressure Pw1 and the second braking pressure Pw2. The main controller then operates the electric cylinder 51 of the normal supply source based on the target braking pressure PwTr and the acquired braking pressure detection value PwN. A normal supply source is one of the multiple supply sources 50A, 50B that operates to discharge brake fluid when connection control is executed. In other words, among the multiple supply sources 50A, 50B, the one controlled by the main controller is the normal supply source. Therefore, for example, if the first controller 61 is the main controller, the first supply source 50A becomes the normal supply source.

[0048] The acquired braking pressure detection value PwN is the braking pressure detection value of the wheel cylinder corresponding to the supply source that is not the normal supply source among the first braking pressure detection value Pw1S and the second braking pressure detection value Pw2S. Therefore, when the first controller 61 is the main controller, the main controller acquires the second braking pressure detection value Pw2S as the acquired braking pressure detection value PwN. When the second controller 62 is the main controller, the main controller acquires the first braking pressure detection value Pw1S as the acquired braking pressure detection value PwN.

[0049] For example, the main controller drives the electric motor 54 of the normal supply source by executing feedback control that causes the acquired braking pressure detection value PwN to follow the target braking pressure PwTr. Accordingly, the main controller can adjust the first braking pressure Pw1 and the second braking pressure Pw2 such that the first braking pressure Pw1 and the second braking pressure Pw2 become substantially equal.

[0050] <Abnormality Determination Processing> With reference to FIG. 2, the abnormality determination processing executed by the control unit 60 will be described. Both the first controller 61 and the second controller 62 repeatedly execute the abnormality determination processing every predetermined control cycle. In the abnormality determination processing, among the plurality of controllers 61 and 62, one controller determines whether there is a sign of abnormality in the other controller, and determines whether an abnormality has occurred in the other controller.

[0051] In step S11, the controllers 61 and 62 determine whether a signal can be received from the counterpart controller. The counterpart controller as viewed from the first controller 61 is the second controller 62. The counterpart controller as viewed from the second controller 62 is the first controller 61.

[0052] The plurality of controllers 61 and 62 transmit and receive signals every predetermined control cycle. Therefore, when both of the plurality of controllers 61 and 62 are normal, the controllers 61 and 62 can receive a signal from the counterpart controller every predetermined control cycle. On the other hand, if an abnormality actually occurs in the counterpart controller, the controllers 61 and 62 become unable to receive a signal from the counterpart controller.

[0053] In step S11, if controllers 61 and 62 are able to receive a signal from the other controller (S11: YES), controllers 61 and 62 proceed to step S13. The ability of controllers 61 and 62 to receive a signal from the other controller means that information can be mutually obtained between multiple controllers 61 and 62. On the other hand, if controllers 61 and 62 are not able to receive a signal from the other controller (S11: NO), controllers 61 and 62 proceed to step S21. The inability of controllers 61 and 62 to receive a signal from the other controller means that controllers 61 and 62 cannot obtain information from the other controller.

[0054] In step S13, controllers 61 and 62 reset the duration TM to 0 (zero). The duration TM is the duration during which information cannot be obtained from the other controller. Then, controllers 61 and 62 proceed to step S15.

[0055] In step S15, controllers 61 and 62 set both the abnormality warning flag FLG1 and the abnormality confirmation flag FLG2 to off. The abnormality warning flag FLG1 is set to on when it is determined that there is an abnormality warning in the other controller. The abnormality confirmation flag FLG2 is set to on when it is determined that an abnormality has occurred in the other controller. After that, controllers 61 and 62 temporarily terminate the abnormality detection process.

[0056] In step S21, controllers 61 and 62 update the duration TM. In the following step S23, controllers 61 and 62 determine whether the duration TM has reached the abnormality detection time TMth. The abnormality detection time TMth is set as the criterion for determining whether the length of time during which information cannot be obtained from the other controller is relatively long. If the duration TM has reached the abnormality detection time TMth (S23: YES), controllers 61 and 62 proceed to step S25. On the other hand, if the duration TM has not reached the abnormality detection time TMth (S23: NO), controllers 61 and 62 proceed to step S31.

[0057] In step S25, controllers 61 and 62 set both the abnormality prediction flag FLG1 and the abnormality confirmation flag FLG2 to ON. In other words, controllers 61 and 62 determine that an abnormality has occurred in the other controller. Then, controllers 61 and 62 terminate the abnormality detection process. After the abnormality confirmation flag FLG2 is set to ON, controllers 61 and 62 may execute the abnormality detection process at any time. For example, controllers 61 and 62 may execute the abnormality detection process when the driving switch (e.g., the ignition switch) of the vehicle 10 is turned ON.

[0058] In step S31, controllers 61 and 62 determine whether there is a large discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2. Controllers 61 and 62 derive an estimated counter-braking pressure PwRe. The estimated counter-braking pressure PwRe is an estimated value of the braking pressure of the wheel cylinder corresponding to the normal supply source. For example, when shut-off control is being performed, controllers 61 and 62 derive target braking pressures Pw1Tr and Pw2Tr as the estimated counter-braking pressure PwRe. Alternatively, controllers 61 and 62 may use a map showing the relationship between the motor rotation angle θmt of the electric motor 54, which is their controlled object, and the braking pressures Pw1 and Pw2 to derive braking pressures Pw1 and Pw2 according to the motor rotation angle θmt, and set these braking pressures Pw1 and Pw2 as the estimated counter-braking pressure PwRe. Controllers 61 and 62 derive the difference between the estimated counter-braking pressure PwRe and the acquired braking pressure detection value PwN as the braking pressure difference ΔPw. Controllers 61 and 62 determine whether the absolute value of the braking pressure difference ΔPw is greater than or equal to the determination braking pressure difference ΔPwth. The determination braking pressure difference ΔPwth is set as the criterion for determining whether the discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2 is large. Therefore, if the absolute value of the braking pressure difference ΔPw is greater than or equal to the determination braking pressure difference ΔPwth, the discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2 is considered large. On the other hand, if the absolute value of the braking pressure difference ΔPw is less than the determination braking pressure difference ΔPwth, the discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2 is considered not large. If the absolute value of the braking pressure difference ΔPw is greater than or equal to the determination braking pressure difference ΔPwth (S31: YES), controllers 61 and 62 proceed to step S33. On the other hand, if the absolute value of the braking pressure difference ΔPw is less than the determination braking pressure difference ΔPwth (S31: NO), controllers 61 and 62 proceed to step S35.

[0059] In step S33, controllers 61 and 62 set the abnormality prediction flag FLG1 to ON and the abnormality confirmation flag FLG2 to OFF. In other words, if controllers 61 and 62 can estimate that there is a large discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2, they determine that there is an abnormality in the other controller, even if the duration TM has not reached the abnormality determination time TMth. Then, controllers 61 and 62 terminate the abnormality determination time.

[0060] In step S35, controllers 61 and 62 determine whether the deviation ΔYR between the absolute value of the yaw rate YR of the vehicle 10 and the yaw rate determination value YRth is greater than or equal to a predetermined value ΔYRth. The criterion for determining the absolute value of the yaw rate YR is set by the difference with the yaw rate determination value YRth. For example, it is preferable that the yaw rate determination value YRth is set according to the steering angle of the steering wheel of the vehicle 10. For example, it is preferable that the sum of the absolute value of the yaw rate calculated based on the steering angle and a predetermined offset value is set as the yaw rate determination value YRth. In this case, the yaw rate determination value YRth can also be said to be the target value of the yaw rate YR. In other words, the predetermined value ΔYRth is the criterion for determining whether the deviation between the actual value of the yaw rate YR and the target value is large or not.

[0061] The yaw rate of vehicle 10 is an example of a behavioral state value that indicates the behavior of vehicle 10. Therefore, the yaw rate YR corresponds to the "actual value of the behavioral state value," and the yaw rate determination value YRth corresponds to the "determination value of the behavioral state value."

[0062] In step S35, if the deviation ΔYR is less than a predetermined value ΔYRth (S35: NO), controllers 61 and 62 proceed to step S37. On the other hand, if the deviation ΔYR is greater than or equal to a predetermined value ΔYRth (S35: YES), controllers 61 and 62 proceed to step S33. In other words, if the deviation between the absolute value of the actual behavioral state value of the vehicle 10 and the determination value is greater than or equal to a predetermined value, controllers 61 and 62 determine that there is an indication of an abnormality in the other controller, even if the duration TM has not reached the abnormality determination time TMth.

[0063] In step S37, controllers 61 and 62 determine whether they have received a message from the integrated control unit 80 indicating that communication between the integrated control unit 80 and the other controller is malfunctioning. If they have received a message from the integrated control unit 80 indicating that communication between the integrated control unit 80 and the other controller is malfunctioning (S37: YES), controllers 61 and 62 proceed to step S33. That is, if controllers 61 and 62 have received a message from the integrated control unit 80 indicating that information cannot be exchanged between the integrated control unit 80 and the other controller, they determine that there is a sign of malfunction in the other controller, even if the duration TM has not reached the abnormality determination time TMth. On the other hand, if they have not received a message from the integrated control unit 80 indicating that communication between the integrated control unit 80 and the other controller is malfunctioning (S37: NO), controllers 61 and 62 proceed to step S15.

[0064] <Braking Control Process> Referring to Figure 3, the braking control process performed by the control unit 60 will be explained. The braking control process is a flow of processes for applying braking force to the first wheel 11 and the second wheel 12 in accordance with the braking request. The control unit 60 repeatedly executes the braking control process at predetermined control cycles.

[0065] In step S51, controllers 61 and 62 determine whether or not a braking request has been issued for the vehicle 10. If a braking request has been issued (S51: YES), controllers 61 and 62 proceed to step S53. On the other hand, if no braking request has been issued (S51: NO), controllers 61 and 62 terminate the braking control process.

[0066] In step S53, controllers 61 and 62 determine whether the abnormality confirmation flag FLG2 is set to ON. That is, controllers 61 and 62 determine whether an abnormality has occurred in the other controller. If the abnormality confirmation flag FLG2 is set to ON (S53: YES), controllers 61 and 62 proceed to step S73. On the other hand, if the abnormality confirmation flag FLG2 is set to OFF (S53: NO), controllers 61 and 62 proceed to step S55.

[0067] In step S55, controllers 61 and 62 determine whether the abnormality warning flag FLG1 is set to ON. If the abnormality warning flag FLG1 is set to ON (S55: YES), controllers 61 and 62 proceed to step S71. On the other hand, if the abnormality warning flag FLG1 is set to OFF (S55: NO), controllers 61 and 62 proceed to step S57.

[0068] In step S57, controllers 61 and 62 determine whether the state of the switching unit 40 is in a connected state or not. If the state of the switching unit 40 is in a connected state (S57: YES), controllers 61 and 62 proceed to step S59. On the other hand, if the state of the switching unit 40 is not in a connected state (S57: NO), the state of the switching unit 40 is in a disconnected state, and controllers 61 and 62 proceed to step S61.

[0069] In step S59, controllers 61 and 62 set the state of the switching unit 40 to the shut-off state. The first controller 61 closes the first system shut-off valve 42, and the second controller 62 closes the second system shut-off valve 43. Then, controllers 61 and 62 proceed to step S61.

[0070] In step S61, controllers 61 and 62 execute the above-mentioned shutoff control. Specifically, the first controller 61 adjusts the first braking pressure Pw1 by activating the first supply source 50A, and the second controller 62 adjusts the second braking pressure Pw2 by activating the second supply source 50B. Then, controllers 61 and 62 terminate the braking control process.

[0071] In step S71, controllers 61 and 62 determine whether or not vehicle behavior control is being performed. If vehicle behavior control is being performed, the first braking pressure Pw1 and the second braking pressure Pw2 are adjusted individually. Therefore, if connection control is started while vehicle behavior control is being performed, the stability of the vehicle behavior may decrease as the discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2 is eliminated. For this reason, if vehicle behavior control is being performed (S71: YES), even if the abnormality warning flag FLG1 is set to ON, controllers 61 and 62 proceed to step S57. In other words, even if there is an abnormality warning in the other controller, if vehicle behavior control is being performed, switching the control from disconnection control to connection control is prohibited. On the other hand, if vehicle behavior control is not being performed (S71: NO), controllers 61 and 62 proceed to step S73.

[0072] In step S73, controllers 61 and 62 determine whether the state of the switching unit 40 is in the disconnected state or not. If the state of the switching unit 40 is in the disconnected state (S73: YES), controllers 61 and 62 proceed to step S75. On the other hand, if the state of the switching unit 40 is not in the disconnected state (S73: NO), the state of the switching unit 40 is in the connected state, and controllers 61 and 62 proceed to step S77.

[0073] In step S75, controllers 61 and 62 set the state of the switching unit 40 to the communication state. That is, if the first controller 61 is functioning normally, the first controller 61 opens the first system shut-off valve 42 by stopping the power supply to the first system shut-off valve 42. At this time, if an abnormality has already occurred in the second controller 62, the power supply from the second controller 62 to the second system shut-off valve 43 is stopped, so the second system shut-off valve 43 is open. Conversely, if the second controller 62 is functioning normally, the second controller 62 opens the second system shut-off valve 43 by stopping the power supply to the second system shut-off valve 43. At this time, if an abnormality has already occurred in the first controller 61, the power supply from the first controller 61 to the first system shut-off valve 42 is stopped, so the first system shut-off valve 42 is open. After that, controllers 61 and 62 proceed to step S77.

[0074] In step S77, controllers 61 and 62 perform connection control. If the first controller 61 is functioning correctly, it adjusts the first braking pressure Pw1 and the second braking pressure Pw2 by activating the first power source 50A. If the second controller 62 is functioning correctly, it adjusts the first braking pressure Pw1 and the second braking pressure Pw2 by activating the second power source 50B. After that, controllers 61 and 62 temporarily terminate the braking control process.

[0075] <Operation and Effects of this Embodiment> The operation and effects of this embodiment will be described with reference to Figure 4. Here, we will describe the case in which a malfunction occurs only in the first controller 61 among the multiple controllers 61 and 62 during service braking.

[0076] As shown in Figures 4(a) to 4(c), all of the controllers 61 and 62 are functioning normally until timing t11. Therefore, the state of the switching unit 40 is set to the shut-off state. Consequently, if a braking request occurs before timing t11, the shut-off control is executed, and braking force is applied to both the first wheel 11 and the second wheel 12. Specifically, the first controller 61 activates the first power source 50A, adjusting the first braking pressure Pw1, and the second controller 62 activates the second power source 50B, adjusting the second braking pressure Pw2.

[0077] In the example shown in Figure 4, an abnormality occurs in the first controller 61 at timing t11 or later. Immediately afterward at timing t12, the second controller 62 determines that there are signs of an abnormality in the first controller 61. Furthermore, at a slightly later timing t13, the second controller 62 determines that an abnormality has occurred in the first controller 61.

[0078] In Figures 4(b) and 4(c), the state transitions in the braking device 100 of this embodiment are shown by solid lines. On the other hand, the state transitions in the braking device of the comparative example are shown by dashed lines. In the braking device of the comparative example, when the second controller 62 determines that an abnormality has occurred in the first controller 61, the second controller 62 switches the control from interruption control to connection control.

[0079] In the braking device of this comparative example, shut-off control is performed until timing t13, while connection control is performed from timing t13 onward. If the first braking pressure Pw1 and the second braking pressure Pw2 have been adjusted by shut-off control from before timing t11, then if an abnormality occurs in the first controller 61 at timing t11, the first power source 50A will not be able to operate from timing t11 onward. In this case, the power supply to the electric motor 54 is stopped by the first power source 50A. As a result, torque is no longer output from the electric motor 54, causing the piston 53 of the electric cylinder 51 to retract. This causes brake fluid to leak from the first wheel cylinder 211, and consequently the first braking pressure Pw1 decreases. In other words, from timing t11 onward, braking force is applied only to the second wheel 12 of the two wheels 12, not the first wheel 11. Even if some braking force remains to be applied to the first wheel 11, the braking force applied to the first wheel 11 will be significantly smaller than the braking force applied to the second wheel 12. This braking state of the vehicle 10 is described as "single-wheel braking".

[0080] In the comparative example's braking device, at timing t13, while single-wheel braking is being performed, the second controller 62 determines that an abnormality has occurred in the first controller 61, and the control switches from cutoff control to connection control. As a result, brake fluid is supplied to both the first wheel cylinder 211 and the second wheel cylinder 212 by the operation of the second supply source 50B. Therefore, it becomes possible to adjust not only the second braking pressure Pw2 but also the first braking pressure Pw1. In other words, in the comparative example's braking device, the period from timing t11 to timing t13 is the period of single-wheel braking.

[0081] In contrast, in this embodiment, if the second controller 62 determines at timing t12 that there is an indication of an abnormality in the first controller 61, the control switches from disconnection control to connection control. In other words, the period from timing t11 to timing t12 becomes the period of single-wheel braking. Therefore, the braking device 100 of this embodiment can shorten the period of single-wheel braking compared to the braking device of the comparative example.

[0082] The braking device 100 of this embodiment can obtain the following effects: (1) When a braking request occurs while all of the multiple controllers 61 and 62 are functioning normally, the first braking pressure Pw1 and the second braking pressure Pw2 are adjusted by shut-off control. That is, the braking force applied to the first wheel 11 and the braking force applied to the second wheel 12 are adjusted by shut-off control. In this state, an abnormality may occur in only one of the controllers, the first controller 61 and the second controller 62. In this case, the braking pressure of the wheel cylinder corresponding to the controller that has malfunctioned cannot be adjusted, among the first braking pressure Pw1 and the second braking pressure Pw2. As a result, it becomes difficult to apply braking force to the wheel corresponding to the controller that has malfunctioned, among the first wheel 11 and the second wheel 12. If shut-off control is still being executed in this state, the difference in braking force between the first wheel 11 and the second wheel 12 will increase. As a result, while the vehicle 10 is in motion, there is a risk that the vehicle 10 may deviate due to this difference in braking force.

[0083] In this regard, in the braking device 100 of this embodiment, if one of the multiple controllers 61, 62 detects an indication of an abnormality in the other controller, the other controller switches the control from cutoff control to connection control. Then, the state of the switching unit 40 is set to the communication state, and the first braking pressure Pw1 and the second braking pressure Pw2 can be adjusted by operating the supply source corresponding to the other controller among the multiple supply sources 50A, 50B. In other words, the period of single-wheel braking is shortened compared to the braking device of the comparative example above. Therefore, the braking device 100 of this embodiment can ensure the stability of vehicle behavior when an abnormality occurs in the first controller 61 or the second controller 62 while the vehicle 10 is decelerating due to the application of braking force.

[0084] (2) During service braking, the difference between the first braking pressure Pw1 and the second braking pressure Pw2 should be within the permissible range. In other words, if the difference between the first braking pressure Pw1 and the second braking pressure Pw2 exceeds the permissible range during service braking, it is possible that a malfunction has occurred in only one of the multiple controllers 61, 62, and that the braking pressure of the wheel cylinder corresponding to that controller can no longer be adjusted.

[0085] Therefore, in the braking device 100 of this embodiment, even if the duration TM of the state in which one of the multiple controllers 61, 62 is unable to obtain information from the other controller has not reached the abnormality determination time TMth, if it can determine that there is a large discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2, it will determine that there is a sign of an abnormality in the other controller. As a result, in the braking device 100 of this embodiment, it is possible to detect a sign of an abnormality in the first controller 61 or the second controller 62, and consequently, to switch the control from interruption control to connection control at an early stage.

[0086] (3) Furthermore, if the deviation ΔYR between the absolute value of the yaw rate YR and the yaw rate determination value YRth becomes greater than or equal to a predetermined value ΔYRth while the service brake is being applied, it is possible that a malfunction has occurred in only one of the multiple controllers 61, 62, and that the braking pressure of the wheel cylinder corresponding to that controller has become unadjustable.

[0087] Therefore, in the braking device 100 of this embodiment, even if the duration TM of the state in which one of the multiple controllers 61 and 62 is unable to receive information from the other controller has not reached the abnormality determination time TMth, if the above-mentioned deviation ΔYR becomes greater than or equal to a predetermined value ΔYRth, the other controller is configured to determine that there is a sign of abnormality. As a result, in the braking device 100 of this embodiment, it is possible to detect a sign of abnormality in the first controller 61 or the second controller 62, and consequently, to switch the control from interruption control to connection control at an early stage.

[0088] (4) For example, if an abnormality occurs in the first controller 61, not only will the second controller 62 be unable to obtain information from the first controller 61, but information will also not be exchanged between the integrated control device 80 and the first controller 61.

[0089] Therefore, in the braking device 100 of this embodiment, even if the duration TM of the state in which one of the multiple controllers 61, 62 is unable to obtain information from the other controller has not reached the abnormality determination time TMth, if information cannot be exchanged between the integrated control device 80 and the other controller, the other controller is determined to have an indication of an abnormality. As a result, the braking device 100 of this embodiment can detect an indication of an abnormality in the first controller 61 or the second controller 62, and consequently, it can switch the control from interruption control to connection control at an early stage.

[0090] (5) In connection control, it is not possible to intentionally create a braking force difference between the first wheel 11 and the second wheel 12. Therefore, in the braking device 100 of this embodiment, when vehicle behavior control is being performed instead of service braking, one of the multiple controllers 61, 62 is prohibited from switching the control from disconnection control to connection control, even if the other controller has determined that there is an indication of an abnormality. As a result, the braking device 100 of this embodiment can suppress the decrease in vehicle behavior stability caused by forcibly switching the control from disconnection control to connection control.

[0091] <Examples of Modifications> The above embodiment can be implemented with the following modifications. The above embodiment and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0092] - Even though controllers 61 and 62 are not actually malfunctioning, the transmission of information from one controller to the other may temporarily become unreliable. In other words, after one of the multiple controllers 61 and 62 detects signs of malfunction in another controller, communication between the multiple controllers 61 and 62 may be restored. In this case, controllers 61 and 62 may set the malfunction warning flag FLG1 to off. This allows controllers 61 and 62 to switch control back from connection control to disconnection control.

[0093] On the other hand, it is preferable to prohibit the abnormality confirmation flag FLG2 from being switched back from on to off after one of the multiple controllers 61, 62 has determined that an abnormality has occurred in the other controller.

[0094] - It is preferable that controllers 61 and 62 execute connection control if the abnormality prediction flag FLG1 is set to ON while the vehicle 10 is in motion, even if the abnormality confirmation flag FLG2 is not set to ON. On the other hand, if the abnormality prediction flag FLG1 is set to ON while the vehicle 10 is stopped, controllers 61 and 62 may execute connection control only after the abnormality confirmation flag FLG2 is set to ON, provided that the vehicle 10 can be kept stopped.

[0095] In the above embodiment, the abnormality prediction flag FLG1 is set to ON if at least one of the following three conditions (A1), (A2), and (A3) is met.

[0096] (A1) The discrepancy between the first braking pressure Pw1 and the second braking pressure Pw2 is large. (For example, the determination in step S31 in Figure 2 is YES.) (A2) The discrepancy between the absolute value of the actual value of the behavior state value and the determination value is greater than or equal to a predetermined value. (For example, the determination in step S35 in Figure 2 is YES.) (A3) Information cannot be exchanged between the first controller 61 or the second controller 62 and the integrated control device 80. (For example, the determination in step S37 in Figure 2 is YES.) Controllers 61 and 62 may set the abnormality prediction flag FLG1 to ON on the condition that at least two of the above three conditions (A1) to (A2) are met.

[0097] - Controllers 61 and 62 may set the abnormality warning flag FLG1 to ON if they cannot obtain information from the other controller, regardless of whether the above conditions (A1) to (A3) are met.

[0098] - The yaw rate determination value YRth may be fixed to a predetermined value. In this case, the determination in step S35 in Figure 2 may be performed on the condition that the steering angle of the steering wheel is substantially 0 (zero). In other words, if the driver is trying to turn the vehicle 10, the determination in step S35 in Figure 2 may not be performed.

[0099] Controllers 61 and 62 may use lateral acceleration GY instead of yaw rate YR. In this case, lateral acceleration GY corresponds to the actual value of the behavioral state value, and the threshold value of lateral acceleration GY corresponds to the judgment value of the behavioral state value.

[0100] - The electric cylinder 51 may or may not have a return spring that biases the piston 53 in the direction of retraction. - For example, as shown in Figure 5, the braking device 100A may be configured without a reservoir 31.

[0101] The braking device 100A may be configured to include a switching unit 40A as shown in Figure 5. The switching unit 40A includes a communication passage 41 and a system shut-off valve 42A installed in the communication passage 41. The system shut-off valve 42A is a normally open solenoid valve and includes a first solenoid and a second solenoid. When power is supplied to at least one of the first solenoid and the second solenoid, the system shut-off valve 42A is closed. When the power supply to both the first solenoid and the second solenoid is stopped, the system shut-off valve 42A is opened. The first controller 61 controls the power supply to the first solenoid of the system shut-off valve 42A, and the second controller 62 controls the power supply to the second solenoid of the system shut-off valve 42A.

[0102] The detection signal from the first hydraulic pressure sensor 33 may be input to both the first controller 61 and the second controller 62. Similarly, the detection signal from the second hydraulic pressure sensor 35 may be input to both the first controller 61 and the second controller 62.

[0103] The braking device may be configured such that the first supply source 50A can supply brake fluid to the two wheel cylinders even when the switching unit 40 is in the shut-off state. In this case, the two wheel cylinders are connected to the first fluid passage 32. In this respect, the two wheel cylinders correspond to the "first wheel cylinder".

[0104] The braking device may be configured such that the second supply source 50B can supply brake fluid to the two wheel cylinders even when the switching unit 40 is in the shut-off state. In this case, the two wheel cylinders are connected to the second fluid passage 34. In this respect, the two wheel cylinders correspond to the "second wheel cylinders".

[0105] The first and second supply sources may be configured to include pressurizing sources other than the electric cylinder 51, as long as they can supply brake fluid to the wheel cylinder. For example, the first and second supply sources may be configured to include electric pumps.

[0106] - The braking device described above may be applied to a vehicle in which the first wheel 11 and the second wheel 12 are rear wheels. - Controllers 61 and 62 may be configured as circuits including one or more dedicated hardware circuits, such as one or more processors that operate according to a computer program, and dedicated hardware that performs at least some of the various processes, or a combination thereof. Examples of dedicated hardware include application-specific integrated circuits (ASICs). The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to execute processes. Memory, i.e., storage media, includes any available media that can be accessed by a general-purpose or dedicated computer.

[0107] <Other Technical Concepts> The following describes the technical concepts that can be understood from the above embodiments and modified examples. [Note 1] In a situation where the vehicle behavior control is being performed and the difference between the first braking pressure and the second braking pressure is estimated to be within the difference determination value, it is preferable to allow one of the first controller and the second controller to switch the control from the disconnection control to the connection control when it determines that an abnormality has occurred in the other controller.

[0108] In this specification, the expression "at least one" means "one or more" of the desired options. For example, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, if there are three or more options, the expression "at least one" means "only one option" or "a combination of two or more arbitrary options."

Claims

1. Applicable to a vehicle comprising: first wheels and second wheels arranged at different positions in the vehicle width direction; a first wheel cylinder corresponding to the first wheel; and a second wheel cylinder corresponding to the second wheel, the braking device comprising: a first fluid passage which is a brake fluid passage connected to the first wheel cylinder; a second fluid passage which is a brake fluid passage connected to the second wheel cylinder; a first supply source connected to the first fluid passage and discharging brake fluid into the first fluid passage; a second supply source connected to the second fluid passage and discharging brake fluid into the second fluid passage; a switching unit that can switch between a communication state in which the first fluid passage and the second fluid passage are in communication and a disconnection state in which communication between the first fluid passage and the second fluid passage is blocked; a first controller that controls the first supply source and the switching unit; and a second controller which is mutually capable of acquiring information with the first controller and controls the second supply source and the switching unit, wherein each of the plurality of controllers is When information cannot be obtained from the other controller, if the duration of the period during which information cannot be obtained reaches the abnormality determination time, it is determined that an abnormality has occurred in the other controller. If the duration has not reached the abnormality determination time, it is determined that there is a sign of an abnormality in the other controller. The braking device is configured such that, while blocking control is being performed in which communication between the first fluid passage and the second fluid passage is blocked by the control of the switching unit by at least one of the multiple controllers, the first braking pressure, which is the braking pressure of the first wheel cylinder, is adjusted by the operation of the first supply source, and the second braking pressure, which is the braking pressure of the second wheel cylinder, is adjusted by the operation of the second supply source, one of the multiple controllers determines that there is a sign of an abnormality in the other controller, the one controller controls the switching unit to connect the first fluid passage and the second fluid passage, and the one controller operates the supply source corresponding to that one controller among the multiple supply sources to perform connection control to adjust the first and second braking pressures.

2. The braking device according to claim 1, wherein, during the execution of the shutoff control, if the duration of the state in which one of the plurality of controllers is unable to obtain information from the other controller has not reached the abnormality determination time, and the absolute value of the difference between the first braking pressure and the second braking pressure is equal to or greater than the determination braking pressure difference, the other controller is determined to have an indication of an abnormality.

3. The braking device according to claim 1, wherein, during the execution of the shutoff control, if the duration of the state in which one of the plurality of controllers is unable to obtain information from the other controller has not reached the abnormality determination time, and the deviation between the absolute value of the actual value of the behavior state value indicating the behavior of the vehicle and the determined value of the behavior state value is greater than or equal to a predetermined value, the other controller is determined to have an indication of an abnormality.

4. The braking device according to claim 1, further comprising a third controller capable of mutually acquiring information with the first controller and the second controller, wherein one of the first controller and the second controller determines that there is an indication of an abnormality in the other controller when the duration of the state in which it is unable to acquire information from the other controller has not reached the abnormality determination time, and the third controller has received information from the other controller that it is unable to exchange information with the third controller.

5. A braking device according to any one of claims 1 to 4, wherein, in a situation in which vehicle behavior control is being performed to control the behavior of the vehicle by individually adjusting the first braking pressure and the second braking pressure, one of the first controller and the second controller is prohibited from switching the control from the cutoff control to the connection control even if the other controller has determined that there is an indication of an abnormality.

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