Braking device

Abstract

A braking device 30 comprises: a first supply source 60A having an electric cylinder 61; a second supply source 60B having an electric cylinder 61; a switching unit 50; a communication hydraulic circuit 70 that connects input ports 61b of the plurality of electric cylinders 61 to a reservoir 41; a first reservoir shut-off valve 81 that shuts off communication between the input port 61b of the electric cylinder 61 of the first supply source 60A and the reservoir 41; and a second reservoir shut-off valve 82 that shuts off communication between the input port 61b of the electric cylinder 61 of the second supply source 60B and the reservoir 41.

Description

Brake device

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

[0002] Patent Document 1 discloses a brake device including a first electric cylinder connected to a first wheel cylinder via a first liquid passage, and a second electric cylinder connected to a second wheel cylinder via a second liquid passage. The brake device includes a communication passage connecting the first liquid passage and the second liquid passage, two communication valves installed in series in the communication passage, a reservoir for storing brake fluid, an open liquid passage connecting a portion between the two communication valves in the communication passage and the reservoir, and a reservoir shut-off valve installed in the open liquid passage.

[0003] When a braking request occurs under the condition that all of the plurality of electric cylinders are operating normally, the two communication valves and the reservoir shut-off valve are closed. In this state, the hydraulic pressure of the first wheel cylinder is adjusted by the first electric cylinder, and the hydraulic pressure of the second wheel cylinder is adjusted by the second electric cylinder. Such braking control is described as "normal braking control".

[0004] On the other hand, when one of the first electric cylinder and the second electric cylinder becomes inoperable, the two communication valves are opened so that the first liquid passage and the second liquid passage communicate with each other. In this state, when the other electric cylinder operates, the hydraulic pressure of the plurality of wheel cylinders is adjusted. Such braking control is described as "one-sided braking control".

[0005] In a situation where a plurality of electric cylinders are operating due to the execution of the above normal braking control, for example, in the first electric cylinder, a mechanical lock may occur, which is an abnormality in which the piston cannot move. When a mechanical lock occurs, a release process is executed to release the state in which hydraulic pressure is generated in the plurality of wheel cylinders by opening any of the plurality of communication valves and the reservoir shut-off valve to communicate the plurality of wheel cylinders with the reservoir.

[0006] Japanese Unexamined Patent Application Publication No. 2022-27055

[0007] In the braking device described in Patent Document 1, a solenoid valve is used as the reservoir shut-off valve, in which the hydraulic pressure in the first portion of the open fluid passage, which is the part of the reservoir opposite the reservoir shut-off valve, acts in a direction that presses the valve body against the valve seat. Therefore, if the hydraulic pressure in the first portion is higher than the hydraulic pressure in the second portion of the open fluid passage, which is the part between the reservoir and the reservoir shut-off valve, the reservoir shut-off valve is difficult to open.

[0008] Even if the above release process is executed because a mechanical lock occurs in the first electric cylinder during normal braking control, as described above, the reservoir shut-off valve may not open if the hydraulic pressure in the first part of the open fluid passage is high. If the reservoir shut-off valve does not open, the condition in which hydraulic pressure is generated in multiple wheel cylinders cannot be released.

[0009] To solve these problems, we consider using a solenoid valve as the reservoir shut-off valve, in which the hydraulic pressure in the second part of the open fluid passage acts to press the valve body against the valve seat. In this solenoid valve, the hydraulic pressure in the first part of the open fluid passage acts to move the valve body away from the valve seat. In this case, although the reservoir shut-off valve can be opened when the above release process is performed, the following problems arise when the above one-sided braking control is performed.

[0010] In single-sided braking control, with two communication valves open and the first and second fluid passages in communication, one of the multiple electric cylinders is activated. When brake fluid is discharged from this electric cylinder, the fluid pressure in the first part of the open fluid passage becomes higher than the fluid pressure in the second part. Therefore, in order to maintain the closure of the reservoir shut-off valve, a large current must be passed through the reservoir shut-off valve. As a result, the amount of power consumed by the braking system to maintain the state in which communication between the multiple wheel cylinders and the reservoir is interrupted may increase.

[0011] The braking device for solving the above problems is applied to a vehicle equipped with a first wheel cylinder and a second wheel cylinder, and generates braking force in the vehicle by adjusting the hydraulic pressure of the multiple wheel cylinders. The braking device comprises a reservoir for storing brake fluid, a first fluid passage connected to the first wheel cylinder, a second fluid passage connected to the second wheel cylinder, a first electric motor that drives a first piston forward within the first cylinder so that brake fluid from a first hydraulic chamber partitioned by the inner wall of the first cylinder and the first piston is discharged to the first fluid passage via a first output port, a first input port provided in the first cylinder that communicates with the first hydraulic chamber when the first piston is in its most retracted position within its range of motion, and a first electric cylinder configured such that when the first piston moves forward beyond the position where the first input port is provided, the first piston blocks communication between the first input port and the first hydraulic chamber, and a second electric motor that drives a second piston forward within the second cylinder so that brake fluid from a second hydraulic chamber partitioned by the inner wall of the second cylinder and the second piston is discharged. The device comprises a second electric cylinder configured such that liquid is discharged into the second liquid passage via a second output port, and a second input port is provided in the second cylinder that communicates with the second hydraulic chamber when the second piston is in its most retracted position within the range of motion of the second piston, and when the second piston moves forward beyond the position where the second input port is provided, the second piston is configured to block communication between the second input port and the second hydraulic chamber; a switching unit that can switch between a communication state in which the first liquid passage and the second liquid passage are in communication and a blocking state in which communication between the first liquid passage and the second liquid passage is blocked; a communicating hydraulic circuit that connects the first input port and the second input port to the reservoir; and a reservoir blocking mechanism installed in the communicating hydraulic circuit, which includes a first solenoid that switches between communication between the reservoir and the first input port and blocking said communication, and a second solenoid that switches between communication between the reservoir and the second input port and blocking said communication.

[0012] The above braking device has the effect of releasing the hydraulic pressure generated in multiple wheel cylinders when a mechanical lock occurs in one of the multiple electric cylinders, and suppressing an increase in the power consumption of the device.

[0013] Figure 1 is a schematic configuration diagram showing a vehicle equipped with a braking device of the first embodiment. Figure 2 is a schematic cross-sectional view showing the configuration of the electric cylinder equipped with the braking device of Figure 1. Figure 3 is a block diagram showing the functional configuration of the control device and the schematic configuration of the braking unit equipped with the braking device of Figure 1. Figure 4 is a flowchart showing the process flow for confirming that the first reservoir shut-off valve or the second reservoir shut-off valve equipped with the braking device of Figure 1 is operating normally. Figure 5 is a flowchart showing the process flow when a mechanical lock occurs in the electric cylinder of Figure 2. Figure 6 is a schematic configuration diagram showing a vehicle equipped with a braking device of the second embodiment. Figure 7 is a block diagram showing the functional configuration of the control device and the schematic configuration of the braking unit equipped with the braking device of Figure 6. Figure 8 is a schematic configuration diagram showing a vehicle equipped with a braking device of the third embodiment. Figure 9(a) is a schematic cross-sectional view showing the configuration of the electric cylinder equipped with the braking device of the fourth embodiment, and Figure 9(b) is an enlarged view of a part of Figure 9(a). Figure 10 is a flowchart showing part of the series of processes performed when the braking device of the fourth embodiment generates braking force on a vehicle. Figure 11 is a flowchart showing the remaining part of the series of processes performed when the braking device of the fourth embodiment generates braking force on a vehicle. Figures 12(a) to 12(c) are timing charts showing the changes in various parameters when the braking device of the fourth embodiment is activated.

[0014] (First Embodiment) A first embodiment of the braking device will be described with reference to Figures 1 to 5. Figure 1 shows a vehicle 10 equipped with the braking device 30. The vehicle 10 is equipped with a plurality of wheels and a plurality of friction brakes 20 corresponding to each of the plurality of wheels. In Figure 1, the first wheel 11 and the second wheel 12 are shown among the plurality of wheels.

[0015] Each friction brake 20 comprises a wheel cylinder, a rotating body 22, and a friction part 23. The rotating body 22 rotates integrally with the corresponding wheels 11 and 12. The friction brake 20 generates braking force on 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 with higher hydraulic pressure in the wheel cylinder. In other words, the friction brake 20 can generate greater braking force as the hydraulic pressure in the wheel cylinder increases.

[0016] Hereafter, the hydraulic pressure of the wheel cylinder will be referred to as "braking pressure Pwc". The wheel cylinder corresponding to the first wheel 11 will be referred to as "first wheel cylinder 211". The wheel cylinder corresponding to the second wheel 12 will be referred to as "second wheel cylinder 212".

[0017] <Configuration of the braking device> The braking device 30 comprises an operating unit 31, a braking unit 40, and a control device 300. <Operating unit> The operating unit 31 comprises a braking operating member 32, a first braking sensor 33, and a second braking sensor 34. The braking operating member 32 is an instrument operated by the driver of the vehicle 10 when adjusting the deceleration of the vehicle 10. An example of the braking operating member 32 is a brake pedal.

[0018] The first braking sensor 33 and the second braking sensor 34 each detect braking operation information, which is information relating to the driver's operation of the braking operation member 32. An example of the first braking sensor 33 and the second braking sensor 34 is a stroke sensor that detects the amount of operation of the driver's braking operation member 32 as braking operation information. The amount of operation based on the detection signal of the first braking sensor 33 and the amount of operation based on the detection signal of the second braking sensor 34 are referred to as "braking operation amount Ba". The detection signal of the first braking sensor 33 is input to the first controller 310 of the control device 300, which will be described later. The detection signal of the second braking sensor 34 is input to the second controller 320 of the control device 300, which will be described later.

[0019] <Braking Unit> The braking unit 40 generates braking force on the vehicle 10 by adjusting the braking pressure Pwc of the first wheel cylinder 211 and the braking pressure Pwc of the second wheel cylinder 212. The braking unit 40 includes a reservoir 41, a first fluid passage 42, a second fluid passage 44, a switching unit 50, a first supply source 60A, a second supply source 60B, a communicating hydraulic circuit 70, and a reservoir shut-off mechanism 80.

[0020] The reservoir 41 stores brake fluid and is open to the atmosphere. The first fluid passage 42 and the second fluid passage 44 are passages through which brake fluid flows. The first fluid passage 42 is connected to the first wheel cylinder 211. The second fluid passage 44 is connected to the second wheel cylinder 212. A first hydraulic pressure sensor 43 is connected to the first fluid passage 42 to detect the brake fluid pressure in the first fluid passage 42. A second hydraulic pressure sensor 45 is connected to the second fluid passage 44 to detect the brake fluid pressure in the second fluid passage 44. Each of the first hydraulic pressure sensor 43 and the second hydraulic pressure sensor 45 outputs a detection signal to the control device 300 according to the detection result. For example, the detection signal from the first hydraulic pressure sensor 43 is input to the first controller 310 of the control device 300, which will be described later. The detection signal from the second hydraulic pressure sensor 45 is input to the second controller 320 of the control device 300, which will be described later. Hereafter, the detected value of the braking pressure Pwc of the first wheel cylinder 211 based on the detection signal of the first hydraulic sensor 43 will be referred to as "first braking pressure detected value Pwc1". The detected value of the braking pressure Pwc of the second wheel cylinder 212 based on the detection signal of the second hydraulic sensor 45 will be referred to as "second braking pressure detected value Pwc2".

[0021] The switching unit 50 is configured to switch between a connected state, which connects the first fluid passage 42 and the second fluid passage 44, and a blocked state, which blocks the connection between the first fluid passage 42 and the second fluid passage 44. For example, the switching unit 50 has a connecting passage 51, which is a passage through which brake fluid flows, a first system shut-off valve 52, and a second system shut-off valve 53. Of the two ends of the connecting passage 51, the first end is connected to the first fluid passage 42, and the second end is connected to the second fluid passage 44.

[0022] The first system shut-off valve 52 and the second system shut-off valve 53 are installed in series in the communication passage 51. Of the two system shut-off valves 52 and 53, the one located near the first hydraulic pressure sensor 43 is the first system shut-off valve 52, while the one located near the second hydraulic pressure sensor 45 is the second system shut-off valve 53. Both the first system shut-off valve 52 and the second system shut-off valve 53 are normally open solenoid valves. Therefore, when the energization is stopped in both the first solenoid 52a of the first system shut-off valve 52 (see Figure 3) and the second solenoid 53a of the second system shut-off valve 53 (see Figure 3), the first system shut-off valve 52 and the second system shut-off valve 53 open as shown in Figure 1. As a result, the first liquid passage 42 and the second liquid passage 44 communicate via the communication passage 51. Thus, the state of the switching unit 50 when both the first system shut-off valve 52 and the second system shut-off valve 53 are open corresponds to the "communication state".

[0023] On the other hand, if power is supplied to the first solenoid 52a of the first system shut-off valve 52, the first system shut-off valve 52 closes. If power is supplied to the second solenoid 53a of the second system shut-off valve 53, the second system shut-off valve 53 closes. When at least one of the first system shut-off valve 52 and the second system shut-off valve 53 is closed, communication between the first liquid passage 42 and the second liquid passage 44 via the communication passage 51 is cut off. The state of the switching unit 50 when both the first system shut-off valve 52 and the second system shut-off valve 53 are closed corresponds to the "shut-off state".

[0024] Each of the first supply source 60A and the second supply source 60B has an electric cylinder 61. The configuration of the electric cylinder 61 will be described later. The first supply source 60A is connected to the first fluid passage 42. The first supply source 60A can supply brake fluid to the first wheel cylinder 211 via the first fluid passage 42. The second supply source 60B is connected to the second fluid passage 44. The second supply source 60B can supply brake fluid to the second wheel cylinder 212 via the second fluid passage 44.

[0025] The hydraulic communication circuit 70 connects the first input port and the second input port to the reservoir 41. The first input port is the input port 61b of the electric cylinder 61 of the first supply source 60A, which will be described later. The second input port is the input port 61b of the electric cylinder 61 of the second supply source 60B, which will be described later. In the example shown in Figure 1, the hydraulic communication circuit 70 includes a first reservoir opening fluid passage 71 that connects the input port 61b corresponding to the first input port to the reservoir 41, and a second reservoir opening fluid passage 72 that connects the input port 61b corresponding to the second input port to the reservoir 41.

[0026] The reservoir shut-off mechanism 80 is installed in the communicating hydraulic circuit 70. The reservoir shut-off mechanism 80 is configured to switch between communicating and shutting off the communication between the input port 61b corresponding to the first input port and the reservoir 41, and communicating and shutting off the communication between the input port 61b corresponding to the second input port and the reservoir 41. For example, the reservoir shut-off mechanism 80 includes a first reservoir shut-off valve 81 installed in the first reservoir opening fluid passage 71 and a second reservoir shut-off valve 82 installed in the second reservoir opening fluid passage 72.

[0027] The first reservoir shut-off valve 81 and the second reservoir shut-off valve 82 are both normally open solenoid valves. Therefore, when the power supply to the first solenoid 81a, which is the solenoid of the first reservoir shut-off valve 81 shown in Figure 3, is stopped, the first reservoir shut-off valve 81 opens. As a result, the input port 61b corresponding to the first input port communicates with the reservoir 41 via the first reservoir open fluid passage 71. On the other hand, when power is supplied to the first solenoid 81a, the first reservoir shut-off valve 81 closes. In this case, the first reservoir shut-off valve 81 cuts off the communication between the input port 61b corresponding to the first input port and the reservoir 41.

[0028] When the power supply to the second solenoid 82a, which is the solenoid of the second reservoir shut-off valve 82 shown in Figure 3, is stopped, the second reservoir shut-off valve 82 opens. As a result, the input port 61b corresponding to the second input port communicates with the reservoir 41 via the second reservoir open fluid passage 72. On the other hand, when power is supplied to the second solenoid 82a, the second reservoir shut-off valve 82 closes. In this case, the second reservoir shut-off valve 82 cuts off the communication between the input port 61b corresponding to the second input port and the reservoir 41.

[0029] Returning to Figure 1, the portion of the first reservoir opening passage 71 between the input port 61b corresponding to the first input port and the first reservoir shut-off valve 81 is the first opening passage portion, while the portion between the first reservoir shut-off valve 81 and the reservoir 41 is the second opening passage portion. The first reservoir shut-off valve 81 is configured to seat its valve body on the valve seat using the hydraulic pressure of the second opening passage portion. The configuration of the second reservoir shut-off valve 82 is the same as that of the first reservoir shut-off valve 81, so the explanation of the configuration of the second reservoir shut-off valve 82 will be omitted.

[0030] <Electric Cylinder> The configuration of the electric cylinder 61 will be described with reference to Figures 1 and 2. The electric cylinder 61 has a cylinder 62, a piston 63, an electric motor 64, and a conversion mechanism 65. The piston 63 is provided in a state that it can reciprocate within the cylinder 62. The conversion mechanism 65 converts the rotation of the output shaft of the electric motor 64 into the linear movement of the piston 63.

[0031] Inside the cylinder 62, a hydraulic chamber Re for storing brake fluid is partitioned by the peripheral wall of the cylinder 62 and the piston 63. The position of the piston 63 inside the cylinder 62 can be changed by driving the electric motor 64. Hereafter, the direction of linear movement of the piston 63 when reducing the volume of the hydraulic chamber Re will be described as the "forward direction Za". The opposite direction of the forward direction Za will be described as the "reverse direction Zb". The reverse direction Zb is also the direction of linear movement of the piston 63 when increasing the volume of the hydraulic chamber Re. When the piston 63 moves in the forward direction Za, it will be described as "the piston 63 moves forward", and when the piston 63 moves in the reverse direction Zb, it will be described as "the piston 63 moves backward".

[0032] The electric cylinder 61 does not have a return spring that biases the piston 63 in the retraction direction Zb. The range in which the piston 63 can be moved by the electric cylinder 61 is described as the "movable range RA of the piston 63". Within the movable range RA, the retraction end, i.e., the position furthest back in the retraction direction Zb, is described as the "last retracted position Pf".

[0033] The cylinder 62 is provided with an output port 61a and an input port 61b that connect the hydraulic chamber Re to the outside. The output port 61a is always open. The output port 61a of the electric cylinder 61 of the first supply source 60A is connected to the first fluid passage 42. The output port 61a of the electric cylinder 61 of the second supply source 60B is connected to the second fluid passage 44.

[0034] The input port 61b communicates with the hydraulic chamber Re when the piston 63 is in its rearmost position Pf. Specifically, the piston 63 has a through hole 63a. When the piston 63 is in its rearmost position Pf, the input port 61b communicates with the hydraulic chamber Re via the through hole 63a. When the piston 63 moves forward from the rearmost position Pf, the communication between the hydraulic chamber Re and the input port 61b via the through hole 63a is cut off. If the piston 63 continues to move forward even though the communication between the hydraulic chamber Re and the input port 61b is cut off, the hydraulic pressure in the hydraulic chamber Re increases. As a result, the brake fluid in the hydraulic chamber Re is discharged through the output port 61a.

[0035] Furthermore, within the cylinder 62, seal rings 66 are provided in the portion Za in the forward direction from the input port 61b, and in the portion Zb in the backward direction from the input port 61b. In other words, the input port 61b is located between the two seal rings 66. As a result, the seal rings 66 are interposed between the inner wall of the cylinder 62 and the piston 63. Therefore, communication between the input port 61b and the hydraulic chamber Re via the space between the inner wall of the cylinder 62 and the piston 63 is blocked by the seal rings 66.

[0036] The electric motor 64 has a motor angle sensor 67. The motor angle sensor 67 outputs a detection signal to the control device 300 in accordance with the change in the rotation angle of the output shaft of the electric motor 64. Specifically, the motor angle sensor 67 of the first power source 60A outputs a detection signal to the first controller 310 of the control device 300, which will be described later. The motor angle sensor 67 of the second power source 60B outputs a detection signal to the second controller 320 of the control device 300, which will be described later. Hereafter, the rotation angle of the electric motor 64 based on the detection signal of the motor angle sensor 67 will be referred to as "motor rotation angle θmt".

[0037] When the motor rotation angle θmt increases due to the drive of the electric motor 64, the piston 63 moves forward. As a result, brake fluid from the hydraulic chamber Re is discharged through the output port 61a. This supplies brake fluid to the wheel cylinders 211 and 212, increasing the braking pressure Pwc. On the other hand, when the motor rotation angle θmt decreases due to the drive of the electric motor 64, the piston 63 moves backward. As a result, brake fluid flows into the hydraulic chamber Re through the output port 61a. In this case, brake fluid flows out from the wheel cylinders 211 and 212, decreasing the braking pressure Pwc.

[0038] In this embodiment, the electric cylinder 61 of the first supply source 60A corresponds to the "first electric cylinder". Therefore, the electric motor 64 of the first supply source 60A corresponds to the "first electric motor". The piston 63 of the first supply source 60A corresponds to the "first piston". The cylinder 62 of the first supply source 60A corresponds to the "first cylinder". The hydraulic chamber Re of the first supply source 60A corresponds to the "first hydraulic chamber". The output port 61a of the first supply source 60A corresponds to the "first output port". The input port 61b of the first supply source 60A corresponds to the "first input port".

[0039] Furthermore, the electric cylinder 61 of the second power source 60B corresponds to the "second electric cylinder". Therefore, the electric motor 64 of the second power source 60B corresponds to the "second electric motor". The piston 63 of the second power source 60B corresponds to the "second piston". The cylinder 62 of the second power source 60B corresponds to the "second cylinder". The hydraulic chamber Re of the second power source 60B corresponds to the "second hydraulic chamber". The output port 61a of the second power source 60B corresponds to the "second output port". The input port 61b of the second power source 60B corresponds to the "second input port".

[0040] <Control Device> The control device 300 will be described with reference to Figure 1. The control device 300 comprises a first controller 310 and a second controller 320. Each of the first controller 310 and the second controller 320 is configured to send and receive information and commands via the in-vehicle network 330. An example of the in-vehicle network 330 is a CAN bus. "CAN" is an abbreviation for "Controller Area Network".

[0041] The first controller 310 receives detection signals from the first braking sensor 33 and the first hydraulic pressure sensor 43. The first controller 310 controls the electric cylinder 61 of the first power source 60A, the first system shut-off valve 52 of the switching unit 50, and the second reservoir shut-off valve 82 of the reservoir shut-off mechanism 80. Controlling the first system shut-off valve 52 means controlling the energization of the first solenoid 52a. Controlling the second reservoir shut-off valve 82 means controlling the energization of the second solenoid 82a.

[0042] Detection signals from the second braking sensor 34 and the second hydraulic pressure sensor 45 are input to the second controller 320. The second controller 320 controls the electric cylinder 61 of the second supply source 60B, the second system shut-off valve 53 of the switching unit 50, and the first reservoir shut-off valve 81 of the reservoir shut-off mechanism 80. Controlling the second system shut-off valve 53 means controlling the energization of the second solenoid 53a. Controlling the first reservoir shut-off valve 81 means controlling the energization of the first solenoid 81a.

[0043] The first controller 310 has a first processing circuit 311. The second controller 320 has a second processing circuit 321. An example of the plurality of processing circuits 311, 321 is an electronic control unit. In this case, the first processing circuit 311 includes a CPU 312 and a memory 313 that stores a control program executed by the CPU 312. The second processing circuit 321 includes a CPU 322 and a memory 323 that stores a control program executed by the CPU 322. The first processing circuit 311 can control the electric cylinder 61 of the first supply source 60A, the first system shut-off valve 52, and the second reservoir shut-off valve 82 by the CPU 312 executing the control program in the memory 313. The second processing circuit 321 can control the electric cylinder 61 of the second supply source 60B, the second system shut-off valve 53, and the first reservoir shut-off valve 81 by the CPU 322 executing the control program in the memory 323.

[0044] <Normal braking control> The normal braking control executed by the control device 300 will be described. The normal braking control is a braking control executed when both of the two electric cylinders 61 operate normally.

[0045] In normal braking control, the control device 300 sets the state of the switching unit 50 to a shut-off state. Specifically, the first processing circuit 311 closes the first system shut-off valve 52. The second processing circuit 321 closes the second system shut-off valve 53. The control device 300 also activates the reservoir shut-off mechanism 80 to shut off communication between the input port 61b corresponding to the first input port and the reservoir 41, and between the input port 61b corresponding to the second input port and the reservoir 41. Specifically, the first processing circuit 311 closes the second reservoir shut-off valve 82. The second processing circuit 321 closes the first reservoir shut-off valve 81. In this state, the first processing circuit 311 adjusts the braking pressure Pwc of the first wheel cylinder 211 by activating the electric cylinder 61 of the first supply source 60A. The second processing circuit 321 adjusts the braking pressure Pwc of the second wheel cylinder 212 by operating the electric cylinder 61 of the second supply source 60B.

[0046] In the electric cylinder 61, the amount of movement of the piston 63 from its furthest retracted position Pf to the forward direction Za is the "amount of forward movement of the piston 63 STp". In this case, there is a correspondence between the amount of forward movement of the piston 63 STp and the consumption amount, which is the amount of brake fluid supplied from the supply source to the wheel cylinder. There is also a correspondence between the braking pressure Pwc of the wheel cylinder and the consumption amount. Furthermore, there is a correspondence between the amount of forward movement of the piston 63 STp and the motor rotation angle θmt. Therefore, it can be said that there is a correspondence between the amount of forward movement STp and the motor rotation angle θmt and the braking pressure Pwc.

[0047] Therefore, the first processing circuit 311 sets the target motor rotation angle θmtTr1, which is the target value of the motor rotation angle θmt, based on the required value of the braking pressure Pwc of the first wheel cylinder 211. Then, the first processing circuit 311 operates the electric cylinder 61 of the first power source 60A by performing feedback control to make the motor rotation angle θmt of the electric motor 64 of the first power source 60A follow the target motor rotation angle θmtTr1.

[0048] Further, the second processing circuit 321 sets a target motor rotation angle θmtTr2 based on the required value of the braking pressure Pwc of the second wheel cylinder 212. Then, the second processing circuit 321 operates the electric cylinder 61 of the second supply source 60B by executing feedback control to make the motor rotation angle θmt of the electric motor 64 of the second supply source 60B follow the target motor rotation angle θmtTr2.

[0049] <One-sided braking control> One-sided braking control executed by the control device 300 will be described. One-sided braking control is braking control executed when an abnormality has occurred only in one of the two electric cylinders 61. The abnormality of the electric cylinder 61 here means that the position of the piston 63 cannot be controlled in the electric cylinder 61. Therefore, not only when an abnormality occurs in the electric cylinder 61 itself, but also when an abnormality occurs in the processing circuit that controls the electric cylinder 61 or when an abnormality occurs in the motor angle sensor 67, it can be regarded that an abnormality has occurred in the electric cylinder 61.

[0050] In one-sided braking control, the control device 300 sets the state of the switching unit 50 to the communicating state. Specifically, the first processing circuit 311 opens the first system shut-off valve 52 while closing the second reservoir shut-off valve 82. The second processing circuit 321 opens the second system shut-off valve 53 while closing the first reservoir shut-off valve 81. In this state, the control device 300 adjusts the braking pressure Pwc of the first wheel cylinder 211 and the second wheel cylinder 212 by operating the electric cylinder 61 in which no abnormality has occurred among the two electric cylinders 61. Hereinafter, the electric cylinder 61 in which no abnormality has occurred may also be described as a "normal electric cylinder 61".

[0051] For example, if an abnormality occurs in the electric cylinder 61 of the second power source 60B, the first processing circuit 311 closes the second reservoir shut-off valve 82 and then operates the electric cylinder 61 of the first power source 60A to adjust the braking pressure Pwc of the first wheel cylinder 211 and the second wheel cylinder 212. At this time, the first processing circuit 311 sets the target braking pressure PwcTr, which is the target value of the braking pressure Pwc, based on the required value of the braking pressure Pwc. Then, the first processing circuit 311 operates the electric cylinder 61 of the first power source 60A by performing feedback control to make the braking pressure Pwc of the multiple wheel cylinders 211 and 212 follow the target braking pressure PwcTr.

[0052] Furthermore, the one-sided braking control when a malfunction occurs only in the electric cylinder 61 of the first power source 60A is the same as the one-sided braking control when a malfunction occurs only in the electric cylinder 61 of the second power source 60B. Therefore, the explanation of the one-sided braking control when a malfunction occurs only in the electric cylinder 61 of the first power source 60A will be omitted.

[0053] <Functional Configuration of the Control Device> Referring to Figure 3, the functional configuration of the control device 300 will be described. The first processing circuit 311 functions as a first control unit M11, a first mechanical lock determination unit M13, and a first verification unit M15 when the CPU 312 executes the control program for the memory 313. The second processing circuit 321 functions as a second control unit M21, a second mechanical lock determination unit M23, and a second verification unit M25 when the CPU 322 executes the control program for the memory 323.

[0054] The first control unit M11 controls the electric cylinder 61 (i.e., the first electric cylinder) and the second reservoir shut-off valve 82 of the first power source 60A. Controlling the second reservoir shut-off valve 82 means controlling the energization of the second solenoid 82a. The first control unit M11 also controls the first system shut-off valve 52 of the switching unit 50. Controlling the first system shut-off valve 52 means controlling the energization of the first solenoid 52a.

[0055] The second control unit M21 controls the electric cylinder 61 (i.e., the second electric cylinder) and the first reservoir shut-off valve 81 of the second power source 60B. Controlling the first reservoir shut-off valve 81 means controlling the energization of the first solenoid 81a. The second control unit M21 also controls the second system shut-off valve 53 of the switching unit 50. Controlling the second system shut-off valve 53 means controlling the energization of the second solenoid 53a.

[0056] The first mechanical lock determination unit M13 determines whether or not a mechanical lock has occurred in the electric cylinder 61 of the first power source 60A (i.e., the first electric cylinder). A mechanical lock is an example of an abnormality that can occur in the electric cylinder 61. When a mechanical lock occurs in the electric cylinder 61, the position of the piston 63 does not change even when power is supplied to the electric motor 64.

[0057] The first mechanical lock determination unit M13 determines whether a mechanical lock has occurred in the electric cylinder 61 of the first power source 60A while the first control unit M11 is operating the electric cylinder 61 of the first power source 60A. For example, the first mechanical lock determination unit M13 monitors the change in the first braking pressure detection value Pwc1 when the first control unit M11 is operating the electric cylinder 61 of the first power source 60A in order to vary the braking pressure Pwc of the first wheel cylinder 211. The first mechanical lock determination unit M13 then determines that a mechanical lock has occurred in the electric cylinder 61 of the first power source 60A if the duration of the state in which the first braking pressure detection value Pwc1 does not change, even when the first control unit M11 is operating the electric cylinder 61 as described above, exceeds a predetermined abnormality determination time.

[0058] The second mechanical lock determination unit M23 determines whether or not a mechanical lock has occurred in the electric cylinder 61 of the second power source 60B (i.e., the second electric cylinder). The second mechanical lock determination unit M23 determines whether or not a mechanical lock has occurred in the electric cylinder 61 of the second power source 60B while the second control unit M21 is operating the electric cylinder 61 of the second power source 60B. For example, the second mechanical lock determination unit M23 monitors the change in the detected second braking pressure value Pwc2 when the second control unit M21 is operating the electric cylinder 61 of the second power source 60B in order to vary the braking pressure Pwc of the second wheel cylinder 212. The second mechanical lock determination unit M23 then determines that a mechanical lock has occurred in the electric cylinder 61 of the second power source 60B if the duration of the state in which the detected second braking pressure value Pwc2 does not change, even when the second control unit M21 is operating the electric cylinder 61 as described above, exceeds a predetermined abnormality determination time.

[0059] The first confirmation unit M15 performs a confirmation process to confirm that the second reservoir shut-off valve 82 is operating normally. The normal operation of the second reservoir shut-off valve 82 means that it can shut off communication between the input port 61b corresponding to the second input port and the reservoir 41. In this respect, the first confirmation unit M15 corresponds to the "confirmation unit". The first confirmation unit M15 performs the confirmation process when the state of the switching unit 50 is in a communication state and the input port 61b of the electric cylinder 61 of the second supply source 60B is open. Hereafter, the confirmation process performed by the first confirmation unit M15 may be referred to as the "first confirmation process".

[0060] The second verification unit M25 performs a verification process to confirm that the first reservoir shut-off valve 81 is operating normally. The normal operation of the first reservoir shut-off valve 81 means that it can shut off communication between the input port 61b corresponding to the first input port and the reservoir 41. The second verification unit M25 performs the verification process when the state of the switching unit 50 is in a communication state and the input port 61b of the electric cylinder 61 of the first supply source 60A is open. Hereafter, the verification process performed by the second verification unit M25 may be referred to as the "second verification process".

[0061] <Verification Process> Referring to Figure 4, the process flow when the above verification process is executed will be explained. The case in which it is confirmed that the first reservoir shutoff valve 81 is operating normally will be explained. In this case, in Figure 4, "M" is set to 2 and "N" is set to 1.

[0062] In step S11, the control device 300 sets the state of the switching unit 50 to a communication state. That is, the first processing circuit 311 functions as the first control unit M11 and opens the first system shut-off valve 52. The second processing circuit 321 functions as the second control unit M21 and opens the second system shut-off valve 53.

[0063] In the subsequent step S13, the second processing circuit 321 of the control device 300 functions as the second control unit M21, thereby opening the second input port of the second electric cylinder. Specifically, the second processing circuit 321 drives the electric motor 64 so that the piston 63 of the electric cylinder 61 of the second supply source 60B retracts to its rearmost position Pf, thereby opening the input port 61b of the electric cylinder 61. As a result, the hydraulic chamber Re of the electric cylinder 61 communicates with the second reservoir opening fluid passage 72 via the through hole 63a and the input port 61b.

[0064] In the next step S15, the first processing circuit 311 functions as the first confirmation unit M15 to perform a confirmation process, i.e., the first confirmation process. Specifically, in step S17, the first processing circuit 311 closes the second reservoir shutoff valve 82 by supplying power to the second solenoid 82a. In the following step S19, the first processing circuit 311 increases the braking pressure Pwc of the multiple wheel cylinders 211, 212 by operating the electric cylinder 61 of the first power source 60A, which is the first electric cylinder.

[0065] Then, in step S21, the first processing circuit 311 determines whether the first braking pressure detection value Pwc1 is increasing due to the operation of the electric cylinder 61 of the first supply source 60A. If the second system shut-off valve 53 is properly closed by the processing in step S17, the multiple wheel cylinders 211 and 212 are not in communication with the reservoir 41, so the braking pressure Pwc increases. Therefore, if the first braking pressure detection value Pwc1 is increasing (S21: YES), the first processing circuit 311 proceeds to step S23. On the other hand, if the first braking pressure detection value Pwc1 is not increasing (S21: NO), the first processing circuit 311 proceeds to step S25.

[0066] In step S23, the first processing circuit 311 determines that the second reservoir shut-off valve 82 is operating normally. This allows the first processing circuit 311 to confirm that the second reservoir shut-off valve 82 can shut off communication between the input port 61b of the electric cylinder 61 of the second supply source 60B, i.e., the second input port, and the reservoir 41. The first processing circuit 311 then terminates the confirmation process.

[0067] In step S25, the first processing circuit 311 determines that the second reservoir shut-off valve 82 is not operating properly. This allows the first processing circuit 311 to confirm that the second reservoir shut-off valve 82 cannot shut off the communication between the input port 61b of the electric cylinder 61 of the second supply source 60B, i.e., the second input port, and the reservoir 41. The first processing circuit 311 then terminates the confirmation process.

[0068] The above describes the processing flow when the first processing circuit 311 executes the first verification process. The processing flow when the second processing circuit 321 executes the second verification process is the same as when the first verification process is executed. That is, in Figure 4, if you set "M" to 1 and "N" to 2, you can explain the processing flow when the second verification process is executed.

[0069] <Reservoir Release Process> Under normal braking control conditions, when both electric cylinders 61 are operating, mechanical lock may occur in only one of the two electric cylinders 61. In this case, by connecting the two wheel cylinders 211 and 212 to the reservoir 41, the braking pressure Pwc generated in the two wheel cylinders 211 and 212 can be released.

[0070] Therefore, referring to Figure 5, the process flow when mechanical lock occurs in only one of the two electric cylinders 61 will be explained. This process flow will be referred to as the "reservoir release process".

[0071] This section describes the case where a mechanical lock occurs in the first electric cylinder 61 of the first power source 60A, which is one of the two electric cylinders 61, during the execution of normal braking control. In this case, in Figure 5, "M" is set to 2 and "N" is set to 1.

[0072] In step S41, the first processing circuit 311 determines whether the two electric cylinders 61 are operating. If both electric cylinders 61 are operating (S41: YES), the process proceeds to step S43. On the other hand, if at least one of the two electric cylinders 61 is not operating (S41: NO), the reservoir release process is terminated.

[0073] In step S43, the first processing circuit 311 functions as the first mechanical lock determination unit M13 to determine whether or not a mechanical lock has occurred in the electric cylinder 61 of the first power source 60A, which is the first electric cylinder. If the first processing circuit 311 determines that a mechanical lock has occurred in the electric cylinder 61 (S43: YES), the process proceeds to step S45. On the other hand, if the first processing circuit 311 determines that a mechanical lock has not occurred in the electric cylinder 61 (S43: NO), the reservoir release process is terminated.

[0074] In step S45, the first processing circuit 311 functions as the first control unit M11 and opens the second reservoir shut-off valve 82. The first processing circuit 311 can open the second reservoir shut-off valve 82 by stopping the power supply to the second solenoid 82a. As a result, the input port 61b of the electric cylinder 61 of the second power source 60B, which is the second electric cylinder, communicates with the reservoir 41.

[0075] In the following step S47, the control device 300 sets the state of the switching unit 50 to a communication state. That is, the first processing circuit 311 functions as the first control unit M11 and opens the first system shut-off valve 52. The second processing circuit 321 functions as the second control unit M21 and opens the second system shut-off valve 53.

[0076] In the next step S49, the second processing circuit 321 functions as the second control unit M21 and drives the electric motor 64 in the electric cylinder 61 of the second supply source 60B, which is the second electric cylinder, so that the piston 63, which is the second piston, retracts to the rearmost position Pf. When the piston 63 reaches the rearmost position Pf, the hydraulic chamber Re communicates with the reservoir 41 via the input port 61b. Then the reservoir opening process is completed.

[0077] The above describes the first reservoir release process, which is the reservoir release process when a mechanical lock occurs in the first electric cylinder. The second reservoir release process, which is the reservoir release process when a mechanical lock occurs in the second electric cylinder, is equivalent to the first reservoir release process. That is, in Figure 5, the second reservoir release process can be described by setting "M" to 1 and "N" to 2.

[0078] <Operation and Effects of this Embodiment> (1) In the electric cylinder 61 of the first supply source 60A, which is the first electric cylinder, when the piston 63 moves forward from the rearmost position Pf, the input port 61b of the electric cylinder 61 is closed by the piston 63. In this state, the hydraulic chamber Re of the electric cylinder 61 is cut off from the reservoir 41. Therefore, the hydraulic pressure in the first reservoir opening passage 71 does not increase.

[0079] Therefore, when the electric cylinder 61 of the first power source 60A is operated by normal braking control, the first reservoir shut-off valve 81 can be kept closed even if the electromagnetic force that presses the valve body against the valve seat in the first reservoir shut-off valve 81 is not very large. In other words, the first reservoir shut-off valve 81 can be kept closed even if the amount of current supplied to the first solenoid 81a is relatively small. Consequently, the control device 300 can suppress the increase in power consumption of the braking device 30 when it is operating the electric cylinder 61 of the first power source 60A (i.e., the first electric cylinder) by normal braking control to adjust the braking pressure Pwc of the first wheel cylinder 211.

[0080] In the electric cylinder 61 of the second power source 60B, which is the second electric cylinder, when the piston 63 moves forward from its rearmost position Pf, the input port 61b of the electric cylinder 61 is blocked by the piston 63. In this state, the hydraulic chamber Re of the electric cylinder 61 is isolated from the reservoir 41.

[0081] Therefore, when the electric cylinder 61 of the second power source 60B is operated by normal braking control, the closed state of the second reservoir shut-off valve 82 can be maintained even if the electromagnetic force generated by the second reservoir shut-off valve 82 is not very large. In other words, the closed state of the second reservoir shut-off valve 82 can be maintained even if the amount of current supplied to the second solenoid 82a of the second reservoir shut-off valve 82 is relatively small. Consequently, the control device 300 can suppress the increase in power consumption of the braking device 30 when it is operating the electric cylinder 61 of the second power source 60B (i.e., the second electric cylinder) by normal braking control to adjust the braking pressure Pwc of the second wheel cylinder 212.

[0082] If a mechanical lock occurs in only one of the two electric cylinders 61 during normal braking control, the reservoir shut-off valve, which had been blocking communication between the input port 61b of the normal electric cylinder 61 and the reservoir 41, opens. If the normal electric cylinder 61 is the electric cylinder 61 of the first power source 60A, the first reservoir shut-off valve 81 opens (step S45 in Figure 5).

[0083] Next, the state of the switching unit 50 is changed to the communication state (step S47 in Figure 5). After that, the piston 63 in the normal electric cylinder 61 is retracted to the last retracted position Pf (step S49 in Figure 5). As a result, the two wheel cylinders 211 and 212 communicate with the reservoir 41 via the hydraulic chamber Re and input port 61b of the normal electric cylinder 61. Consequently, the brake fluid from the two wheel cylinders 211 and 212 flows out into the reservoir 41, and the state in which braking pressure Pwc has been generated in the multiple wheel cylinders 211 and 212 is released.

[0084] Therefore, the control device 300 can both release the braking pressure Pwc generated in multiple wheel cylinders 211, 212 when a mechanical lock occurs in one of the two electric cylinders 61, and suppress the increase in power consumption of the braking device 30.

[0085] (2) The first processing circuit 311 controls the energization of the electric cylinder 61 of the first supply source 60A, the first system shut-off valve 52 of the switching unit 50, and the second solenoid 82a of the reservoir shut-off mechanism 80. The second processing circuit 321 controls the energization of the electric cylinder 61 of the second supply source 60B, the second system shut-off valve 53 of the switching unit 50, and the first solenoid 81a of the reservoir shut-off mechanism 80.

[0086] As a result, even if an abnormality occurs in only one of the processing circuits, the first processing circuit 311 or the second processing circuit 321, the other processing circuit can adjust the braking pressure Pwc of the multiple wheel cylinders 211 and 212 by operating the electric cylinder 61.

[0087] For example, suppose an abnormality occurs only in the first processing circuit 311 of the two processing circuits 311 and 321. In this case, the power supply to the electric cylinder 61 of the first power source 60A, the first solenoid 52a of the first system shut-off valve 52, and the second solenoid 82a of the reservoir shut-off mechanism 80, which are controlled by the first processing circuit 311, is stopped. In this state, the second processing circuit 321 closes the first reservoir shut-off valve 81 by supplying power to the first solenoid 81a. The second processing circuit 321 then opens the second system shut-off valve 53. Since the power supply to the first solenoid 52a of the first system shut-off valve 52 is stopped, the first system shut-off valve 52 is open. Therefore, by opening the second system shut-off valve 53, the second processing circuit 321 can set the state of the switching unit 50 to a connected state. As a result, the second processing circuit 321 can prevent the two wheel cylinders 211 from communicating with the reservoir 41 via the input port 61b of the electric cylinder 61 of the first supply source 60A.

[0088] In this state, the second processing circuit 321 operates the electric cylinder 61 of the second supply source 60B in one-sided braking control. This allows the second processing circuit 321 to adjust the braking pressure Pwc of the two wheel cylinders 211 and 212.

[0089] Conversely, if, for example, an abnormality occurs only in the second processing circuit 321 of the two processing circuits 311 and 321, the first processing circuit 311 closes the second reservoir shut-off valve 82. Then, the first processing circuit 311 opens the second system shut-off valve 53 to set the state of the switching unit 50 to a connected state. In this state, the first processing circuit 311 can adjust the braking pressure Pwc of the two wheel cylinders 211 and 212 by operating the electric cylinder 61 of the first supply source 60A in the one-sided braking control.

[0090] (3) When the switching unit 50 is in a communication state and the input port 61b of the electric cylinder 61 of the second supply source 60B is open, the first processing circuit 311 performs the first confirmation process. In the first confirmation process, the first processing circuit 311 closes the second reservoir shutoff valve 82 by energizing the second solenoid 82a. The first processing circuit 311 then monitors the change in braking pressure Pwc by operating the electric cylinder 61 of the first supply source 60A. This allows the first processing circuit 311 to confirm whether or not the communication between the input port 61b of the electric cylinder 61 of the second supply source 60B and the reservoir 41 can be cut off by energizing the second solenoid 82a.

[0091] The second processing circuit 321 can confirm whether or not the communication between the input port 61b of the electric cylinder 61 of the first power source 60A and the reservoir 41 can be interrupted by energizing the first solenoid 81a, by performing a second verification process under the same conditions as described above.

[0092] (Second Embodiment) A second embodiment of the braking device will be described with reference to Figures 6 and 7. In the second embodiment, the configuration of the switching section, the communicating hydraulic circuit, and the reservoir shutoff mechanism differs from that of the first embodiment. In the following description, the parts that differ from the first embodiment will be mainly described, and the same reference numerals will be used for components that are the same as in the first embodiment to avoid redundant explanations.

[0093] Referring to Figures 6 and 7, the braking unit 40A of the braking device 30 of this embodiment will be described. The braking unit 40A generates braking force on the vehicle 10 by adjusting the braking pressure Pwc of the first wheel cylinder 211 and the braking pressure Pwc of the second wheel cylinder 212. The braking unit 40A includes a reservoir 41, a first fluid passage 42, a second fluid passage 44, a switching unit 50A, a first supply source 60A, a second supply source 60B, a communicating hydraulic pressure circuit 70A, and a reservoir shut-off mechanism 80A.

[0094] The switching unit 50A is configured to switch between a connected state, which connects the first liquid passage 42 and the second liquid passage 44, and a blocked state, which blocks the connection between the first liquid passage 42 and the second liquid passage 44. For example, the switching unit 50A has a connecting passage 51 and a system shut-off valve 55A installed in the connecting passage 51. In the example shown in Figure 6, one system shut-off valve 55A is installed in the connecting passage 51. The system shut-off valve 55A is a normally open solenoid valve. Therefore, when power is supplied to the solenoid of the system shut-off valve 55A, the system shut-off valve 55A is closed. On the other hand, when the power supply to the solenoid of the system shut-off valve 55A is stopped, the system shut-off valve 55A is open. In other words, the state of the switching unit 50A when the system shut-off valve 55A is closed corresponds to the "blocked state". On the other hand, the state of the switching unit 50A when the system shut-off valve 55A is open corresponds to the "connected state".

[0095] As shown in Figure 7, the system shut-off valve 55A has a first solenoid 55Aa and a second solenoid 55Ab as solenoids. Therefore, the system shut-off valve 55A opens when the power supply to both the first solenoid 55Aa and the second solenoid 55Ab is stopped. On the other hand, the system shut-off valve 55A closes when power is supplied to at least one of the first solenoid 55Aa and the second solenoid 55Ab. The power supply to the first solenoid 55Aa is controlled by the first processing circuit 311. The power supply to the second solenoid 55Ab is controlled by the second processing circuit 321. Therefore, the system shut-off valve 55A can be closed not only by the control of the first processing circuit 311, but also by the control of the second processing circuit 321.

[0096] As shown in Figure 6, the hydraulic communication circuit 70A has a reservoir communication fluid passage 73A. The reservoir communication fluid passage 73A is connected to the reservoir 41. The reservoir communication fluid passage 73A branches into two as it moves away from the connection point with the reservoir 41. Of the branched fluid passages, one is connected to the input port 61b of the electric cylinder 61 of the first supply source 60A, while the other is connected to the input port 61b of the electric cylinder 61 of the second supply source 60B. The portion of the reservoir communication fluid passage 73A between the branching point P1 where it branches into two fluid passages and the reservoir 41 is the common fluid passage 73Aa. The portion of the reservoir communication fluid passage 73A between the input port 61b of the electric cylinder 61 of the first supply source 60A and the branching point P1 is the first branched fluid passage 73Ab. Of the reservoir communication fluid passage 73A, the portion between the input port 61b of the electric cylinder 61 of the second supply source 60B and the branching point P1 is the second branch fluid passage 73Ac.

[0097] The reservoir shut-off mechanism 80A is installed in the connecting hydraulic circuit 70A. The reservoir shut-off mechanism 80A has a reservoir shut-off valve 83A installed in the common fluid passage 73Aa. The reservoir shut-off valve 83A is a normally open solenoid valve. Therefore, when the reservoir shut-off valve 83A is closed, communication between the input ports 61b of the two electric cylinders 61 and the reservoir 41 is cut off. On the other hand, when the reservoir shut-off valve 83A is open, communication between the input ports 61b of the two electric cylinders 61 and the reservoir 41 is established.

[0098] As shown in Figure 7, the reservoir shut-off valve 83A has a first solenoid 83Aa and a second solenoid 83Ab as solenoids. Therefore, the reservoir shut-off valve 83A opens when the power supply to both the first solenoid 83Aa and the second solenoid 83Ab is stopped. On the other hand, the reservoir shut-off valve 83A closes when power is supplied to at least one of the first solenoid 83Aa and the second solenoid 83Ab. The power supply to the first solenoid 83Aa is controlled by the second processing circuit 321. The power supply to the second solenoid 83Ab is controlled by the first processing circuit 311. Therefore, the reservoir shut-off valve 83A can be closed not only by the control of the second processing circuit 321, but also by the control of the first processing circuit 311.

[0099] The braking device 30 of this embodiment provides the same operation and effect as the braking device 30 of the first embodiment. (Third Embodiment) The third embodiment of the braking device will be described with reference to Figure 8. The third embodiment differs from the first embodiment in that the braking unit includes a master cylinder. In the following description, the parts that differ from the first embodiment will be mainly described, and the same reference numerals will be used for components identical to those in the first embodiment to avoid redundant explanations.

[0100] Referring to Figure 8, the braking unit 40B of the braking device 30 of this embodiment will be described. The braking unit 40B includes a reservoir 41, a first fluid passage 42, a second fluid passage 44, a switching unit 50, a first supply source 60A, a second supply source 60B, a communicating hydraulic pressure circuit 70, and a reservoir shut-off mechanism 80, as well as a master cylinder 90, a stroke simulator 95, and a simulator shut-off valve 97.

[0101] The master cylinder 90 is installed in the communication hydraulic circuit 70. Specifically, it is located in the portion of the communication hydraulic circuit 70 between the reservoir 41 and the reservoir shut-off mechanism 80. The master cylinder 90 is a so-called tandem-type master cylinder. That is, the master cylinder 90 is provided with a first master chamber Rm1 that communicates with the first reservoir opening fluid passage 71, and a second master chamber Rm2 that communicates with the second reservoir opening fluid passage 72. When the braking operating member 32 is not operated, the first master chamber Rm1 and the second master chamber Rm2 each communicate with the reservoir 41. On the other hand, when the braking operating member 32 is operated, the two master pistons 91 move in accordance with the displacement of the braking operating member 32, thereby shutting off communication between the first master chamber Rm1 and the second master chamber Rm2 and the reservoir 41. The first master chamber Rm1 is always in communication with the first reservoir opening fluid passage 71. Similarly, the second master chamber Rm2 is in constant communication with the second reservoir opening fluid passage 72.

[0102] A simulator communication fluid passage 96 is connected to the portion of the first reservoir opening fluid passage 71 between the master cylinder 90 and the first reservoir shut-off valve 81. The stroke simulator 95 is connected to the first reservoir opening fluid passage 71 via the simulator communication fluid passage 96. A simulator shut-off valve 97 is also installed in the simulator communication fluid passage 96.

[0103] When at least one of the two electric cylinders 61 is activated to adjust the braking pressure Pwc of the multiple wheel cylinders 211, 212, the simulator shut-off valve 97 is opened. At the same time, the first reservoir shut-off valve 81 and the second reservoir shut-off valve 82 are closed. As a result, when the driver operates the braking operating member 32, brake fluid is supplied from the first master chamber Rm1 to the stroke simulator 95. This inputs an operating reaction force to the braking operating member 32 corresponding to the amount of brake fluid flowing into the stroke simulator 95.

[0104] The braking device 30 of this embodiment provides the same operation and effect as the braking devices 30 of the above-described multiple embodiments. (Fourth Embodiment) The fourth embodiment of the braking device will be described with reference to Figures 9 to 12. In the following description, the parts that differ from the first embodiment will be mainly described, and the same reference numerals will be used for the same component components as in the first embodiment to avoid redundant explanations.

[0105] <Electric Cylinder> The configuration of the electric cylinder 61A provided in the braking device 30 of the fourth embodiment will now be described. As shown in Figure 9(a), the electric cylinder 61A, like the electric cylinder 61 shown in Figure 2, has a cylinder 62, a piston 63, an electric motor 64, and a conversion mechanism 65. The cylinder 62 is provided with an output port 61a and an input port 61b. The output port 61a of the electric cylinder 61A of the first supply source 60A is connected to the first fluid passage 42. The output port 61a of the electric cylinder 61A of the second supply source 60B is connected to the second fluid passage 44.

[0106] The input port 61b communicates with the hydraulic chamber Re when the piston 63 is in its furthest retracted position Pf. Specifically, when the piston 63 is in its furthest retracted position Pf, the input port 61b communicates with the hydraulic chamber Re via the through hole 63a. When the piston 63 moves forward from its furthest retracted position Pf, the communication between the hydraulic chamber Re and the input port 61b via the through hole 63a is cut off.

[0107] A pressure-receiving seal 66A is installed on the inner wall of cylinder 62 in the forward direction Za beyond the input port 61b. A gas-liquid barrier seal 66B is installed on the inner wall of cylinder 62 in the backward direction Zb beyond the input port 61b. The pressure-receiving seal 66A and the gas-liquid barrier seal 66B form an annular shape centered on the axis of cylinder 62. These seals 66A and 66B are in contact with the piston 63 around its entire circumference. Therefore, the pressure-receiving seal 66A can restrict the outflow of brake fluid from the hydraulic chamber Re to the input port 61b by contacting the piston 63. The gas-liquid barrier seal 66B can restrict the outflow of brake fluid from the hydraulic chamber Re to the outside of the electric cylinder 61A through the space between cylinder 62 and piston 63 by contacting the piston 63.

[0108] Figure 9(b) shows the cross-sectional shape of the gas-liquid barrier seal 66B. As shown in Figure 9(b), the cross-sectional shape of the gas-liquid barrier seal 66B is C-shaped. Specifically, an annular open space 661 is formed in the gas-liquid barrier seal 66B, opening to the portion of the circumferential surface of the gas-liquid barrier seal 66B located in the forward direction Za.

[0109] When the hydraulic pressure chamber Re and the input port 61b are in communication and the hydraulic pressure chamber Re increases as the piston 63 moves forward, the hydraulic pressure in the input port 61b also increases, and therefore the hydraulic pressure in the open space 661 of the gas-liquid barrier seal 66B also increases. As a result, the gas-liquid barrier seal 66B expands in the radial direction around the axis of the cylinder 62. Consequently, the force pressing the gas-liquid barrier seal 66B against the piston 63 increases, and the degree of contact between the gas-liquid barrier seal 66B and the piston 63 increases. This improves the sealing performance. However, if the force pressing the gas-liquid barrier seal 66B against the piston 63 is too large and the piston 63 moves in a straight line, wear of the gas-liquid barrier seal 66B is likely to progress.

[0110] In the braking device 30 of this embodiment, the electric cylinder 61A of the first supply source 60A corresponds to the "first electric cylinder". Therefore, the pressure receiving seal 66A of the electric cylinder 61A of the first supply source 60A corresponds to the "first pressure receiving seal". The gas-liquid barrier seal 66B of the electric cylinder 61A of the first supply source 60A corresponds to the "first gas-liquid barrier seal".

[0111] Furthermore, the electric cylinder 61A of the second supply source 60B corresponds to the "second electric cylinder." In addition, the pressure-receiving seal 66A of the electric cylinder 61A of the second supply source 60B may be described as the "second pressure-receiving seal," and the gas-liquid barrier seal 66B of the electric cylinder 61A of the second supply source 60B may be described as the "second gas-liquid barrier seal."

[0112] <Control device> The control device 300 controls the electric cylinder 61A of the first supply source 60A, the electric cylinder 61A of the second supply source 60B, the first reservoir shut-off valve 81, and the second reservoir shut-off valve 82. Controlling the first reservoir shut-off valve 81 means controlling the energization of the first solenoid 81a of the first reservoir shut-off valve 81. Controlling the second reservoir shut-off valve 82 means controlling the energization of the second solenoid 82a of the second reservoir shut-off valve 82. Therefore, the control device 300 corresponds to the "control unit".

[0113] <Braking Process> Referring to Figures 10 and 11, a series of processes performed by the control device 300 when generating braking force on the vehicle 10 will be described. The control device 300 repeatedly performs this series of processes at predetermined control cycles.

[0114] In step S61, the control device 300 determines whether or not a braking request has been issued for the vehicle 10. For example, if the braking operating member 32 is being operated, it can be considered that a braking request has been issued. Also, if another on-board control device requests deceleration of the vehicle 10, it can be considered that a braking request has been issued. If the control device 300 determines that a braking request has been issued (S61: YES), the control device 300 proceeds to step S63. On the other hand, if the control device 300 determines that no braking request has been issued (S61: NO), the control device 300 proceeds to step S121.

[0115] In step S63, the control device 300 determines whether all of the multiple electric cylinders 61A are operating normally. If all of the multiple electric cylinders 61A are operating normally (S63: YES), the control device 300 performs normal braking control. That is, the control device 300 proceeds to step S65. On the other hand, if only one of the multiple electric cylinders 61A is operating normally (S63: NO), the control device 300 performs one-sided braking control. That is, the control device 300 proceeds to step S91.

[0116] <Normal Braking Control> In step S65, the control device 300 derives a target control forward amount STpATr, which is the target value of the control forward amount STpA of the piston 63. The control forward amount STpA is the amount of forward movement of the piston 63 from its position at the time the braking request is generated. As will be described in detail later, in the braking device 30 of this embodiment, when a braking request is generated, all of the reservoir shut-off valves 81 and 82 are closed and the piston 63 is moved forward. Therefore, the control forward amount STpA can be said to be the amount of forward movement of the piston 63 from the time when the reservoir shut-off valves 81 and 82 are closed. When the driver is operating the braking operation member 32, the control device 300 derives the target control forward amount STpATr such that, for example, the value increases as the braking operation amount Ba increases. Also, for example, when another control device requests deceleration of the vehicle 10, the control device 300 derives a value corresponding to that request as the target control forward amount STpATr.

[0117] In the following step S67, the control device 300 determines whether the valve open flag FLG is set to off. As will be described in more detail later, when normal braking control is being performed, a valve open flag FLG is provided for each of the first supply source 60A and the second supply source 60B.

[0118] If the valve opening flag FLG for the first power source 60A is set to OFF (S67: YES), the control device 300 proceeds to step S69 as a process to control the system of the first power source 60A. On the other hand, if the valve opening flag FLG for the first power source 60A is set to ON (S67: NO), the control device 300 proceeds to step S80 as a process to control the system of the first power source 60A.

[0119] If the valve opening flag FLG for the second supply source 60B is set to OFF (S67: YES), the control device 300 proceeds to step S69 as a process to control the system of the second supply source 60B. On the other hand, if the valve opening flag FLG for the second supply source 60B is set to ON (S67: NO), the control device 300 proceeds to step S80 as a process to control the system of the second supply source 60B.

[0120] In step S69, the control device 300 closes the reservoir shut-off valve. For example, if the open flag FLG for the first power source 60A is set to ON, the control device 300 closes the first reservoir shut-off valve 81. In other words, the control device 300 cuts off communication between the input port 61b (i.e., the first input port) of the electric cylinder 61A of the first power source 60A and the reservoir 41 by controlling the energization of the first solenoid 81a of the first reservoir shut-off valve 81. For example, if the open flag FLG for the second power source 60B is set to ON, the control device 300 closes the second reservoir shut-off valve 82. In other words, the control device 300 cuts off communication between the input port 61b (i.e., the second input port) of the electric cylinder 61A of the second power source 60B and the reservoir 41 by controlling the energization of the second solenoid 82a of the second reservoir shut-off valve 82. Then, the control device 300 proceeds to step S71.

[0121] In step S71, the control device 300 operates the electric cylinder 61A based on the target control forward amount STpATr. For example, if the valve opening flag FLG for the first supply source 60A is set to ON, the control device 300 operates the electric cylinder 61A of the first supply source 60A. If the valve opening flag FLG for the second supply source 60B is set to ON, the control device 300 operates the electric cylinder 61A of the second supply source 60B.

[0122] Here, there is a correspondence between the controlled forward movement STpA of the piston 63 of the electric cylinder 61A and the consumption amount, which is the amount of brake fluid supplied from the supply source to the wheel cylinder. There is also a correspondence between the braking pressure Pwc of the wheel cylinder and the consumption amount. Furthermore, there is a correspondence between the controlled forward movement STpA and the motor rotation amount Qmt, which is the rotation amount of the electric motor 64. Therefore, it can be said that there is a correspondence between the controlled forward movement STpA and motor rotation amount Qmt and the braking pressure Pwc.

[0123] Therefore, the control device 300 derives a target rotation amount QmtTr, which is a target value for the motor rotation amount Qmt, based on the target control forward amount STpATr. For example, the control device 300 derives the target rotation amount QmtTr such that the value increases as the target control forward amount STpATr increases. The control device 300 then sets the sum of the motor rotation angle θmt at the time the reservoir shut-off valve is closed and the target rotation amount QmtTr as the target motor rotation angles θmtTr1 and θmtTr2. The first processing circuit 311 of the control device 300 then operates the electric cylinder 61A of the first power source 60A by performing feedback control to make the motor rotation angle θmt of the electric motor 64 of the first power source 60A follow the target motor rotation angle θmtTr1. The second processing circuit 321 of the control device 300 operates the electric cylinder 61A of the second power source 60B by performing feedback control to make the motor rotation angle θmt of the electric motor 64 of the second power source 60B follow the target motor rotation angle θmtTr2.

[0124] In step S73, when the valve opening flag FLG for the first supply source 60A is set to off, the control device 300 determines whether the first damping pressure detection value Pwc1 is greater than or equal to the determination fluid pressure Pwcth. In step S73, when the valve opening flag FLG for the second supply source 60B is set to off, the control device 300 determines whether the second damping pressure detection value Pwc2 is greater than or equal to the determination fluid pressure Pwcth.

[0125] When the reservoir shut-off valve is closed and the hydraulic chamber Re and the input port 61b are in communication, if the hydraulic pressure in the hydraulic chamber Re increases, the hydraulic pressure in the input port 61b, which is in communication with the hydraulic chamber Re, also increases. When the hydraulic pressure in the input port 61b increases, the hydraulic pressure in the open space 661 of the gas-liquid barrier seal 66B also increases. As a result, the force pressing the gas-liquid barrier seal 66B against the piston 63 increases. In this case, if this force is too large, wear of the gas-liquid barrier seal 66B is likely to progress as the piston 63 moves in a straight line. Therefore, a criterion for determining whether or not wear of the gas-liquid barrier seal 66B is likely to progress is set as the judgment hydraulic pressure Pwcth.

[0126] If the first damping pressure detection value Pwc1 is greater than or equal to the determination fluid pressure Pwcth (S73: YES) while the valve opening flag FLG for the first supply source 60A is set to OFF, the control device 300 proceeds to step S75 as processing for the system of the first supply source 60A. In step S75, the control device 300 opens the reservoir shut-off valve 81, which is the reservoir shut-off valve for the system of the first supply source 60A. That is, the control device 300 controls the energization of the first solenoid 81a of the first reservoir shut-off valve 81, thereby connecting the input port 61b (i.e., the first input port) of the electric cylinder 61A of the first supply source 60A with the reservoir 41. Then, in step S77, the control device 300 sets the valve opening flag FLG for the first supply source 60A to ON. After that, the control device 300 temporarily terminates processing for the system of the first supply source 60A.

[0127] If the valve opening flag FLG for the second supply source 60B is set to OFF and the second damping pressure detection value Pwc2 is greater than or equal to the determination fluid pressure Pwcth (S73: YES), the control device 300 proceeds to step S75 as processing for the system of the second supply source 60B. In step S75, the control device 300 opens the reservoir shut-off valve 82, which is the reservoir shut-off valve for the system of the second supply source 60B. That is, the control device 300 controls the energization of the second solenoid 82a of the second reservoir shut-off valve 82 to connect the input port 61b (i.e., the second input port) of the electric cylinder 61A of the second supply source 60B with the reservoir 41. Then, in step S77, the control device 300 sets the valve opening flag FLG for the second supply source 60B to ON. After that, the control device 300 temporarily terminates processing for the system of the second supply source 60B.

[0128] On the other hand, if the first damping pressure detection value Pwc1 is less than the determination fluid pressure Pwcth while the valve opening flag FLG for the first supply source 60A is set to off (S73: NO), the control device 300 temporarily terminates processing of the system for the first supply source 60A. That is, the control device 300 maintains the state in which the reservoir shut-off valve 81 is closed, i.e., the state in which communication between the input port 61b of the electric cylinder 61A of the first supply source 60A and the reservoir 41 is cut off. If the second damping pressure detection value Pwc2 is less than the determination fluid pressure Pwcth while the valve opening flag FLG for the second supply source 60B is set to off (S73: NO), the control device 300 temporarily terminates processing of the system for the second supply source 60B. In other words, the control device 300 maintains the state in which the reservoir shut-off valve 82 is closed, that is, the state in which communication between the input port 61b of the electric cylinder 61A of the second supply source 60B and the reservoir 41 is cut off.

[0129] In step S80, the control device 300 operates the electric cylinder 61A based on the target control forward amount STpATr, similar to step S71. In step S80, if the valve opening flag FLG for the first supply source 60A is set to ON, the control device 300 operates the electric cylinder 61A of the first supply source 60A. In step S80, if the valve opening flag FLG for the second supply source 60B is set to ON, the control device 300 operates the electric cylinder 61A of the second supply source 60B.

[0130] In the following step S81, the control device 300 determines whether the input port 61b is blocked by the piston 63. In step S81 when the valve opening flag FLG for the first supply source 60A is set to ON, the control device 300 determines whether the input port 61b in the electric cylinder 61A of the first supply source 60A is blocked by the piston 63. In step S81 when the valve opening flag FLG for the second supply source 60B is set to ON, the control device 300 determines whether the input port 61b in the electric cylinder 61A of the second supply source 60B is blocked by the piston 63.

[0131] The control device 300 can estimate the position of the piston 63 within the cylinder 62 based on the motor rotation angle θmt. Based on the position of the piston 63, the control device 300 can determine whether or not the input port 61b is blocked by the piston 63. Blocking the input port 61b by the piston 63 means that the input port 61b and the hydraulic chamber Re are blocked by the piston 63 and the pressure-receiving seal 66A.

[0132] Furthermore, the sensor values ​​of the first hydraulic pressure sensor 43 and the second hydraulic pressure sensor 45, or the pressure detection values ​​of the first master chamber Rm1 and the second master chamber Rm2 may be used to determine whether or not the input port 61b is blocked by the piston 63. In addition, since variations in each element are taken into consideration when determining whether or not the input port 61b is blocked by the piston 63, it is preferable to set thresholds to determine whether or not it is definitely blocked.

[0133] If the control device 300 determines that the input port 61b of the electric cylinder 61A of the first supply source 60A is blocked by the piston 63 while the valve opening flag FLG for the first supply source 60A is set to ON (S81: YES), the control device 300 proceeds to step S83 as processing for the system of the first supply source 60A. On the other hand, if the control device 300 determines that the input port 61b of the electric cylinder 61A of the first supply source 60A is not blocked by the piston 63 (S81: NO), the control device 300 terminates the processing for the system of the first supply source 60A.

[0134] If the control device 300 determines that the input port 61b of the electric cylinder 61A of the second supply source 60B is blocked by the piston 63 while the valve opening flag FLG for the second supply source 60B is set to ON (S81: YES), the control device 300 proceeds to step S83 as processing for the second supply source 60B system. On the other hand, if the control device 300 determines that the input port 61b of the electric cylinder 61A of the second supply source 60B is not blocked by the piston 63 (S81: NO), the control device 300 terminates the processing for the second supply source 60B system.

[0135] In step S83, the control device 300 determines whether the reservoir shut-off valve is open or not. In step S83, if the open flag FLG for the first supply source 60A is on, the control device 300 determines whether the first reservoir shut-off valve 81 is open or not. If the first reservoir shut-off valve 81 is open (S83: YES), the control device 300 proceeds to step S85 as processing for the system of the first supply source 60A. Then, in step S85, the control device 300 closes the first reservoir shut-off valve 81. In other words, the control device 300 cuts off communication between the input port 61b (i.e., the first input port) of the electric cylinder 61A of the first supply source 60A and the reservoir 41 by controlling the energization of the first solenoid 81a of the first reservoir shut-off valve 81. After that, the control device 300 temporarily terminates processing for the system of the first supply source 60A. On the other hand, if the first reservoir shut-off valve 81 is closed (S83: NO), the control device 300 temporarily terminates processing of the first supply source 60A system.

[0136] In step S83, when the valve opening flag FLG for the second power source 60B is on, the control device 300 determines whether the second reservoir shut-off valve 82 is open or not. If the second reservoir shut-off valve 82 is open (S83: YES), the control device 300 proceeds to step S85 as processing for the second power source 60B system. In step S85, the control device 300 closes the second reservoir shut-off valve 82. In other words, the control device 300 cuts off communication between the input port 61b (i.e., the second input port) of the electric cylinder 61A of the second power source 60B and the reservoir 41 by controlling the energization of the second solenoid 82a of the second reservoir shut-off valve 82. After that, the control device 300 temporarily terminates processing for the second power source 60B system. On the other hand, if the second reservoir shut-off valve 82 is closed (S83: NO), the control device 300 temporarily terminates processing of the second supply source 60B system.

[0137] <One-sided braking control> In step S91 shown in Figure 11, the control device 300 sets the target braking pressure PwcTr. When the driver is operating the braking operation member 32, the control device 300 derives the target braking pressure PwcTr such that, for example, the value increases as the braking operation amount Ba increases. Also, for example, when another control device requests deceleration of the vehicle 10, the control device 300 derives a value corresponding to that request as the target braking pressure PwcTr.

[0138] In the following step S93, the control device 300 determines whether the valve opening flag FLG is set to off. The valve opening flag FLG during the execution of one-sided braking control is the valve opening flag for the supply source among the multiple supply sources 60A, 60B that has a normal electric cylinder 61A. If the valve opening flag FLG is set to off (S93: YES), the control device 300 proceeds to step S95. On the other hand, if the valve opening flag FLG is set to on (S93: NO), the control device 300 proceeds to step S110.

[0139] In step S95, the control device 300 closes all of the reservoir shut-off valves 81 and 82. In the following step S97, the control device 300 operates only the normal electric cylinder 61A among the multiple electric cylinders 61A. When one-sided braking control is performed, the state of the switching unit 50 is in communication. Therefore, if the electric cylinder 61A of the first supply source 60A is a normal electric cylinder, the control device 300 performs feedback control to make the first braking pressure detection value Pwc1 follow the target braking pressure PwcTr. If the electric cylinder 61A of the second supply source 60B is a normal electric cylinder, the control device 300 performs feedback control to make, for example, the second braking pressure detection value Pwc2 follow the target braking pressure PwcTr.

[0140] In the next step S99, the control device 300 determines whether the first braking pressure detection value Pwc1 or the second braking pressure detection value Pwc2 is greater than or equal to the determination fluid pressure Pwcth. For example, if the electric cylinder 61A of the first supply source 60A is a normal electric cylinder, the control device 300 determines whether the first braking pressure detection value Pwc1 is greater than or equal to the determination fluid pressure Pwcth. If the electric cylinder 61A of the second supply source 60B is a normal electric cylinder, the control device 300 determines whether the second braking pressure detection value Pwc2 is greater than or equal to the determination fluid pressure Pwcth.

[0141] If the first damping pressure detection value Pwc1 or the second damping pressure detection value Pwc2 is greater than or equal to the determination fluid pressure Pwcth (S99: YES), the control device 300 proceeds to step S101. On the other hand, if the first damping pressure detection value Pwc1 or the second damping pressure detection value Pwc2 is less than the determination fluid pressure Pwcth (S99: NO), the control device 300 terminates the series of processes. That is, the control device 300 maintains the state in which the reservoir shut-off valves 81 and 82 are closed, i.e., the state in which communication between the input port 61b and the reservoir 41 is cut off.

[0142] In step S101, the control device 300 opens only the reservoir shut-off valve corresponding to the normal electric cylinder 61A among the multiple reservoir shut-off valves 81, 82. That is, the control device 300 maintains the state in which the reservoir shut-off valve corresponding to the abnormal electric cylinder 61A remains closed. In the following step S103, the control device 300 sets the open flag FLG to ON. After that, the control device 300 terminates this series of processes.

[0143] In step S110, the control device 300 operates only the normal electric cylinder 61A among the multiple electric cylinders 61A, similar to step S97 above. In the following step S111, the control device 300 determines whether the input port 61b of the normal electric cylinder 61A is blocked by the piston 63. The method for determining whether the input port 61b is blocked by the piston 63 is the same as the method for determining in step S81 above. If the control device 300 determines that the input port 61b is blocked by the piston 63 (S111: YES), the control device 300 proceeds to step S113. On the other hand, if the control device 300 determines that the input port 61b is not blocked by the piston 63 (S111: NO), the control device 300 terminates the series of processes.

[0144] In step S113, the control device 300 determines whether the reservoir shut-off valve corresponding to the normal electric cylinder 61A among the multiple reservoir shut-off valves 81, 82 is open. If the reservoir shut-off valve is open (S113: YES), the control device 300 proceeds to step S115. On the other hand, if the reservoir shut-off valve is closed (S113: NO), the control device 300 terminates the series of processes.

[0145] In step S115, the control device 300 closes the multiple reservoir shut-off valves 81 and 82 in the same manner as in step S85. Then, the control device 300 terminates this series of processes.

[0146] <Control when no braking request has occurred> In step S121 shown in Figure 10, the control device 300 sets the valve open flag FLG to off. Here, the control device 300 sets both the valve open flag FLG for the first supply source 60A and the valve open flag FLG for the second supply source 60B to off. In the following step S123, the control device 300 determines whether at least one of the multiple reservoir shut-off valves 81, 82 is closed. If at least one of the multiple reservoir shut-off valves 81, 82 is closed (S123: YES), the control device 300 proceeds to step S125. On the other hand, if all of the multiple reservoir shut-off valves 81, 82 are open (S123: NO), the control device 300 terminates the series of processes.

[0147] In step S125, the control device 300 determines whether the elapsed time since the point in time when no braking request occurred has reached a predetermined waiting time TMw. The waiting time TMw is set as the time that serves as the criterion for determining whether or not braking requests will occur consecutively. If the elapsed time has not reached the waiting time TMw (S125: NO), the control device 300 temporarily terminates the series of processes while keeping the multiple reservoir shut-off valves 81 and 82 closed. On the other hand, if the elapsed time has reached the waiting time TMw (S125: YES), the control device 300 proceeds to step S127.

[0148] In step S127, the control device 300 opens the multiple reservoir shut-off valves 81 and 82. Specifically, the control device 300 controls the energization of the first solenoid 81a of the first reservoir shut-off valve 81 to connect the input port 61b (i.e., the first input port) of the electric cylinder 61A of the first power source 60A to the reservoir 41. The control device 300 controls the energization of the second solenoid 82a of the second reservoir shut-off valve 82 to connect the input port 61b (i.e., the second input port) of the electric cylinder 61A of the second power source 60B to the reservoir 41. After that, the control device 300 terminates this series of processes.

[0149] <Operation and Effects of this Embodiment> In addition to the operation and effects equivalent to those of the braking device 30 of the first embodiment described above, the braking device 30 of this embodiment can further obtain the operations and effects shown below.

[0150] (4) Consider a comparative example in which the multiple reservoir shut-off valves 81 and 82 are not closed even when a braking request occurs. In this comparative example, before a braking request occurs, the piston 63 of the electric cylinder 61A is waiting in a position where it can communicate the input port 61b and the hydraulic chamber Re through the through hole 63a. When a braking request occurs in this state, the piston 63 moves forward inside the cylinder 62. Then, from the moment the communication between the hydraulic chamber Re and the input port 61b is cut off by the piston 63 blocking the input port 61b, the hydraulic pressure in the hydraulic chamber Re, and consequently the braking pressure Pwc, begins to increase. In other words, there is a possibility that some time lag will occur between the time a braking request occurs and the start of the increase in braking pressure Pwc.

[0151] In this respect, in the braking device 30 of this embodiment, as shown in Figures 12(a) to (c), when a braking request occurs at timing t11, a plurality of reservoir shut-off valves 81 and 82 are closed. As a result, communication between the input port 61b of the electric cylinder 61A and the reservoir 41 is cut off in both the first supply source 60A and the second supply source 60B. Then, when the piston 63 begins to move forward in the cylinder 62, the hydraulic pressure in the hydraulic chamber Re and the braking pressure Pwc increase immediately. In other words, the braking device 30 of this embodiment can generate braking force in the vehicle 10 early after a braking request occurs.

[0152] (5) Furthermore, the fact that the communication between the input port 61b of the electric cylinder 61A and the reservoir 41 is blocked means that the communication between the hydraulic chamber Re and the reservoir 41 is blocked. Therefore, when the piston 63 moves forward in the cylinder 62, the brake fluid from the hydraulic chamber Re does not flow out into the reservoir 41. Accordingly, the braking device 30 of this embodiment can improve the controllability of the braking pressure Pwc and braking force in the initial stages of braking compared to the case in which the communication between the input port 61b and the reservoir 41 is not blocked.

[0153] (6) When the connection between the input port 61b and the reservoir 41 is blocked, and the piston 63 is moving forward in the cylinder 62 while the hydraulic chamber Re and the input port 61b are in communication, the hydraulic pressure in the input port 61b increases. As a result, the electric cylinder 61A exerts a greater force on the gas-liquid seal 66B against the moving piston 63. However, if this force becomes too great, the gas-liquid seal 66B will wear down more easily. If the gas-liquid seal 66B is damaged due to wear, the sealing performance between the gas-liquid seal 66B and the piston 63 will decrease, and as a result, the brake fluid in the hydraulic chamber Re may leak out of the electric cylinder 61A through the gap between the gas-liquid seal 66B and the piston 63.

[0154] In this regard, in the braking device 30 of this embodiment, when the braking pressure detection value becomes equal to or greater than the determination fluid pressure Pwcth at timing t12 while the piston 63 is moving forward in response to the occurrence of a braking request, the reservoir shut-off valve is opened. When the braking pressure detection value Pwc1 becomes equal to or greater than the determination fluid pressure Pwcth, the first reservoir shut-off valve 81 is opened. When the braking pressure detection value Pwc2 becomes equal to or greater than the determination fluid pressure Pwcth, the second reservoir shut-off valve 82 is opened. When the reservoir shut-off valve is opened, the input port 61b of the electric cylinder 61A and the reservoir 41 come into communication. This prevents the fluid pressure in the input port 61b from becoming too high, and also prevents the force pressing the gas-liquid shut-off seal 66B against the piston 63 from becoming too strong. Therefore, the braking device 30 of this embodiment can achieve both the ability to generate braking force in the vehicle 10 early after a braking request is made and the ability to suppress wear of the gas-liquid barrier seal 66B of the electric cylinder 61A.

[0155] (7) When braking force is generated in the vehicle 10 by the operation of the electric cylinder 61A, if the input port 61b is blocked by the piston 63, that is, if the input port 61b and the hydraulic chamber Re are blocked by the piston 63 and the pressure-receiving seal 66A, the hydraulic pressure in the input port 61b will not increase even if the hydraulic pressure in the hydraulic chamber Re increases. Therefore, in the braking device 30 of this embodiment, at timing t13 when the input port 61b can be blocked by the piston 63, the reservoir shut-off valves 81 and 82 are closed again. That is, the communication between the input port 61b and the reservoir 41 is blocked again by the reservoir shut-off valves 81 and 82. Therefore, when the piston 63 is retracted, such as at timing t14 or later, when the hydraulic chamber Re and the input port 61b are able to communicate again, the outflow of brake fluid from the hydraulic chamber Re to the reservoir 41 via the input port 61b is suppressed. As a result, when the piston 63 retracts and the hydraulic chamber Re and the input port 61b come into communication, a rapid decrease in the hydraulic pressure in the hydraulic chamber Re and the braking pressure Pwc is suppressed. Therefore, in the braking device 30 of this embodiment, the decrease in the controllability of the braking pressure Pwc and braking force at the end of one braking period (for example, the period from timing t14 to timing t15 in Figure 12) can be suppressed.

[0156] (8) Consider a comparative example in which, when one-sided braking control is performed, the reservoir shut-off valve corresponding to the abnormal electric cylinder 61A is not closed. In the abnormal electric cylinder 61A, the position of the piston 63 may be fixed with the hydraulic chamber Re and the input port 61b in communication. Therefore, in this comparative example, the reservoir shut-off valve corresponding to the abnormal electric cylinder 61A remains open while the normal electric cylinder 61A operates, and a portion of the brake fluid discharged by the abnormal electric cylinder 61A flows into the reservoir 41 via the input port 61b of the abnormal electric cylinder 61A.

[0157] In this regard, in the braking device 30 of this embodiment, even when one-sided braking control is being executed, when a braking request occurs, all of the reservoir shut-off valves 81 and 82 are closed. That is, the reservoir shut-off valve corresponding to the non-functioning electric cylinder 61A among the multiple electric cylinders 61A is also closed. As a result, the brake fluid discharged by the normal electric cylinder 61A does not flow into the reservoir 41 via the input port 61b of the non-functioning electric cylinder 61A. Therefore, the braking device 30 of this embodiment can appropriately control the braking pressure Pwc and braking force when one-sided braking control is being executed.

[0158] Furthermore, when one-sided braking control is performed, if the braking pressure exceeds the judgment fluid pressure Pwcth due to the operation of a normal electric cylinder 61A, the reservoir shut-off valve corresponding to the normal electric cylinder 61A is opened. On the other hand, the reservoir shut-off valve corresponding to the non-normal electric cylinder 61A remains closed. As a result, the braking device 30 of this embodiment can obtain the same operation and effect as described in (6) above, even when one-sided braking control is performed.

[0159] (Examples of modifications) The above multiple embodiments can be implemented with the following modifications. The above multiple embodiments and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0160] A master cylinder may be provided in the braking section 40A of the second embodiment. In this case, it is preferable to use a so-called single-type master cylinder having one master chamber as the master cylinder.

[0161] - The first processing circuit 311 does not have to function as the first confirmation unit M15. The second processing circuit 321 does not have to function as the second confirmation unit M25. - The first processing circuit 311, i.e., the first control unit M11, may control the energization of the first electric cylinder, the switching unit, and the first solenoid of the reservoir shutoff mechanism. In this case, it is preferable that the second processing circuit 321, i.e., the second control unit M21, controls the energization of the second electric cylinder, the switching unit, and the second solenoid of the reservoir shutoff mechanism.

[0162] - The control device 300 may perform the processing from step S45 onwards in Figure 5 even if no mechanical lock occurs in the first or second electric cylinder. For example, even if an abnormality occurs in the first processing circuit 311 and the first processing circuit 311 is unable to control the first electric cylinder, the control device 300 may connect the hydraulic chamber of the second electric cylinder to the reservoir 41, thereby connecting the two wheel cylinders 211 and 212 to the reservoir 41.

[0163] In the braking device 30 of the fourth embodiment, if a braking request has been generated and the reservoir 41 and the input port 61b are in communication, and the input port 61b is blocked by the piston 63, the reservoir shut-off valves 81 and 82 may be closed at any timing. For example, the control device 300 may close the reservoir shut-off valves 81 and 82 at any timing when the piston 63 is retracted. In this case, the product life of the reservoir shut-off valves 81 and 82 is extended as the period during which the reservoir shut-off valves 81 and 82 are energized is shortened.

[0164] - When normal braking control is being performed in the braking device 30 of the fourth embodiment, the braking device 30 may close the first reservoir shut-off valve 81 when the first braking pressure detection value Pwc1 becomes equal to or greater than the determination fluid pressure Pwcth, and close the second reservoir shut-off valve 82 when the second braking pressure detection value Pwc2 becomes equal to or greater than the determination fluid pressure Pwcth.

[0165] In the braking device 30 of the fourth embodiment, if the control device 300 opens the reservoir shut-off valves 81 and 82 at the timing t12 in Figure 12, it may be configured to keep the reservoir shut-off valves 81 and 82 open until the current braking is completed.

[0166] In the braking device 30 of the fourth embodiment, if it is estimated that the degree of wear of the gas-liquid barrier seal 66B caused by the interruption of communication between the input port 61b and the reservoir 41 is within an acceptable range, the control device 300 may maintain the state in which communication between the input port 61b and the reservoir 41 is interrupted, even if the braking pressure Pwc becomes equal to or greater than the determination fluid pressure Pwcth.

[0167] - When the forward speed of the piston 63 is high, the hydraulic pressure at the input port 61b tends to increase. Therefore, in the braking device 30 of the fourth embodiment, the control device 300 may open the reservoir shut-off valve when the forward speed of the piston 63 exceeds a threshold.

[0168] In the braking device 30 of the fourth embodiment, the control device 300 may open the reservoir shut-off valve in step S75 and then close the reservoir shut-off valve after a predetermined time has elapsed.

[0169] - In the braking device 30 of the fourth embodiment, when a braking request is made to the vehicle 10, multiple reservoir shut-off valves 81 and 82 are closed simultaneously, but the device is not limited to this. In other words, the control device 300 may set a time difference between the closing timing of the first reservoir shut-off valve 81 and the closing timing of the second reservoir shut-off valve 82. For example, the volume of the hydraulic chamber Re may differ between the electric cylinder 61A of the first supply source 60A and the electric cylinder 61A of the second supply source 60B. In this case, the control device 300 may delay the closing of the reservoir shut-off valve corresponding to the electric cylinder 61A having a smaller hydraulic chamber Re compared to the closing of the reservoir shut-off valve corresponding to the electric cylinder 61A having a larger hydraulic chamber Re.

[0170] In the braking device 30 of the fourth embodiment, if both electric cylinders 61A are functioning normally, a braking request may occur for only the first wheel 11 of the two wheels 12. In this case, it is preferable for the control device 300 to close only the first reservoir shut-off valve 81 of the first reservoir shut-off valve 81 and the second reservoir shut-off valve 82, and to close the first system shut-off valve 52 and the second system shut-off valve 53, before operating the electric cylinder 61A of the first supply source 60A.

[0171] In the braking device 30 of the fourth embodiment, the control device 300 may vary the determination hydraulic pressure Pwcth. For example, the control device 300 may set the determination hydraulic pressure Pwcth to a higher value than when the rate of increase of the controlled forward amount STpA is large, if the rate of increase of the controlled forward amount STpA is small.

[0172] - The electric cylinder 61 may have a return spring with such force that the spring biasing force alone is insufficient to return the piston 63 to its rearmost position Pf. - The braking device may be configured so that the first supply source 60A can supply brake fluid to the two wheel cylinders even when the switching units 50, 50A are in a shut-off state. In this case, the two wheel cylinders are connected to the first fluid passage 42. In this respect, the two wheel cylinders correspond to the "first wheel cylinder".

[0173] The braking device may be configured such that the second supply source 60B can supply brake fluid to the two wheel cylinders even when the switching units 50, 50A are in a shut-off state. In this case, the two wheel cylinders are connected to the second fluid passage 44. In this respect, the two wheel cylinders correspond to the "second wheel cylinders".

[0174] - The braking unit may be configured to include a third supply source, in addition to the first supply source 60A and the second supply source 60B. For example, the third supply source may be installed between the first supply source 60A and the second supply source 60B and the first wheel cylinder 211 and the second wheel cylinder 212. In this case, even if the first supply source 60A and the second supply source 60B are not operating, the braking pressure Pwc of the first wheel cylinder 211 and the second wheel cylinder 212 can be adjusted by operating the third supply source. For example, the third supply source may be configured to have an electric pump that discharges brake fluid.

[0175] The first controller 310 and the second controller 320 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. The memory, i.e., storage medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0176] (Other technical ideas) The technical ideas that can be understood from the above multiple embodiments and modifications are described below. [Note 1] The communicating hydraulic circuit has a first reservoir opening fluid passage connecting the reservoir and the first input port, and a second reservoir opening fluid passage connecting the reservoir and the second input port, and the reservoir shut-off mechanism preferably has a first reservoir shut-off valve installed in the first reservoir opening fluid passage and closed by energizing the first solenoid, and a second reservoir shut-off valve installed in the second reservoir opening fluid passage and closed by energizing the second solenoid.

[0177] [Note 2] The reservoir shutoff mechanism is preferably configured to shut off both the communication between the first input port and the reservoir and the communication between the second input port and the reservoir when at least one of the first solenoid and the second solenoid is energized.

[0178] [Note 3] The reservoir shutoff mechanism is preferably configured to connect the first input port to the reservoir and the second input port to the reservoir when both the first solenoid and the second solenoid are not energized.

[0179] [Note 4] If a mechanical lock occurs while the first electric cylinder (or the second electric cylinder) is operating, which is an abnormality that prevents the position of the first piston (or the second piston) from being changed, the first control unit (or the second control unit) preferably connects the second input port (or the first input port) to the reservoir by stopping the power supply to the second solenoid (or the first solenoid), and then the second control unit (or the first control unit) preferably connects the second input port (or the first input port) to the second hydraulic chamber (or the first hydraulic chamber) by driving the second electric motor (or the first electric motor) to retract the second piston (or the first piston) to the rearmost position.

[0180] [Note 5] Preferably, the second electric cylinder includes a second pressure-receiving seal installed on the inner wall of the second cylinder on the forward side of the second input port, which, by contacting the second piston, restricts the outflow of brake fluid from the second hydraulic chamber to the reservoir via the second input port, and a second gas-liquid shut-off seal installed on the inner wall of the second cylinder on the backward side of the second input port, which, by contacting the second piston, restricts the outflow of brake fluid from the second hydraulic chamber to the outside of the second electric cylinder.

[0181] [Note 6] When the braking request occurs, the control unit controls the energization of the first solenoid and the second solenoid to interrupt the communication between the reservoir and the first input port and the communication between the reservoir and the second input port, thereby operating the second electric cylinder. When the second electric cylinder is operating and the hydraulic pressure in the second hydraulic chamber becomes equal to or greater than the determination hydraulic pressure, it is preferable to control the energization of the second solenoid to restore communication between the reservoir and the second input port.

[0182] [Note 7] When the braking request has occurred and the reservoir and the second input port are in communication by controlling the supply of power to the second solenoid, it is preferable that the control unit cuts off the communication between the reservoir and the second input port by controlling the supply of power to the second solenoid when the second input port is blocked by the second piston.

[0183] [Note 8] A braking device that generates braking force in a vehicle by adjusting the hydraulic pressure of a wheel cylinder provided in the vehicle, comprising: a reservoir for storing brake fluid; a supply fluid passage connected to the wheel cylinder; an electric cylinder configured such that when an electric motor drives a piston forward in the cylinder, the brake fluid in a hydraulic chamber partitioned by the inner wall of the cylinder and the piston is discharged to the supply fluid passage via an output port, and an input port is provided in the cylinder that communicates with the hydraulic chamber when the piston is in its most retracted position within the piston's range of motion, and when the piston moves forward beyond the position where the input port is provided, the piston is configured to block communication between the input port and the hydraulic chamber; a reservoir opening fluid passage that connects the input port and the reservoir; and a solenoid valve installed in the reservoir opening fluid passage, which, when open, connects the reservoir and the input port, while when closed, blocks communication between the reservoir and the input port. A braking device comprising: an electric cylinder and a control unit that controls the reservoir shut-off valve, wherein the electric cylinder has a seal installed on the inner wall of the cylinder on the forward side of the input port, which is a pressure-receiving seal that, by contacting the piston, restricts the outflow of brake fluid from the hydraulic chamber to the reservoir via the input port; and a seal installed on the inner wall of the cylinder on the backward side of the input port, which is a gas-liquid shut-off seal that, by contacting the piston, restricts the outflow of brake fluid from the hydraulic chamber to the outside of the electric cylinder, wherein the control unit, when a braking request occurs, closes the reservoir shut-off valve to cut off communication between the reservoir and the input port, and operates the electric cylinder, and thereafter, when the hydraulic pressure in the hydraulic chamber becomes equal to or greater than the determination hydraulic pressure due to the operation of the electric cylinder, opens the reservoir shut-off valve to restore communication between the reservoir and the input port.

[0184] Japanese Patent Publication No. 2009-137376 discloses an example of a braking device that controls the hydraulic pressure of a wheel cylinder by operating an electric cylinder. The electric cylinder of this braking device is provided with an input port that connects the hydraulic chamber to the outside of the cylinder when the piston is in its most retracted position within its range of motion. The input port communicates with the reservoir via a reservoir opening fluid passage. A reservoir shut-off valve, which is a normally open solenoid valve, is installed in the reservoir opening fluid passage. In recent years, there has been a demand for improved accuracy in adjusting the hydraulic pressure of the wheel cylinder in such braking devices.

[0185] 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. A braking device applicable to a vehicle equipped with a first wheel cylinder and a second wheel cylinder, which generates braking force in the vehicle by adjusting the hydraulic pressure of a plurality of the wheel cylinders, comprising: a reservoir for storing brake fluid; a first fluid passage connected to the first wheel cylinder; a second fluid passage connected to the second wheel cylinder; and a first electric cylinder configured such that when a first piston moves forward within the first cylinder by the drive of a first electric motor, brake fluid in a first hydraulic chamber partitioned by the inner wall of the first cylinder and the first piston is discharged to the first fluid passage via a first output port, and a first input port is provided in the first cylinder that communicates with the first hydraulic chamber when the first piston is in its most retracted position within the range of motion of the first piston, and when the first piston moves forward beyond the position where the first input port is provided, the first piston is configured to block communication between the first input port and the first hydraulic chamber. A second electric cylinder is configured such that, when driven by a second electric motor, a second piston advances within the second cylinder, causing brake fluid in a second hydraulic chamber partitioned by the inner wall of the second cylinder and the second piston to be discharged into the second fluid passage via a second output port, and a second input port is provided in the second cylinder that communicates with the second hydraulic chamber when the second piston is in its most retracted position within its range of motion, and when the second piston advances beyond the position where the second input port is provided, the second piston blocks communication between the second input port and the second hydraulic chamber; a switching unit that can switch between a communication state in which the first fluid passage and the second fluid passage are connected and a disconnection state in which communication between the first fluid passage and the second fluid passage is blocked; and a communicating hydraulic circuit that connects the first input port and the second input port to the reservoir. A braking device comprising a reservoir shutoff mechanism installed in the aforementioned hydraulic circuit, which includes a first solenoid for switching between communication between the reservoir and the first input port and shutting off said communication, and a second solenoid for switching between communication between the reservoir and the second input port and shutting off said communication.

2. The braking device according to claim 1, further comprising: a first control unit for controlling the supply of current to the first electric cylinder, the switching unit, and the second solenoid; and a second control unit for controlling the supply of current to the second electric cylinder, the switching unit, and the first solenoid.

3. The braking device according to claim 2, further comprising a confirmation unit that confirms that the state of the switching unit is controlled by at least one of the first control unit and the second control unit to be in the communication state, and that the first control unit controls the supply of power to the first electric cylinder and the second solenoid, thereby blocking communication between the reservoir and the second input port, while the state of the switching unit is controlled by at least one of the first control unit and the second control unit and the second input port is open in the second electric cylinder.

4. The braking device according to claim 1, comprising the first electric cylinder and the second electric cylinder, and a control unit that controls the energization of the first solenoid and the second solenoid, wherein when a braking request is made to the vehicle, the control unit controls the energization of the first solenoid and the second solenoid to interrupt the communication between the reservoir and the first input port and the communication between the reservoir and the second input port, thereby operating the first electric cylinder.

5. The braking device according to claim 4, wherein the first electric cylinder includes a seal installed on the inner wall of the first cylinder on the forward side of the first input port, which contacts the first piston to restrict the outflow of brake fluid from the first hydraulic chamber to the reservoir via the first input port, and a seal installed on the inner wall of the first cylinder on the backward side of the first input port, which contacts the first piston to restrict the outflow of brake fluid from the first hydraulic chamber to the outside of the first electric cylinder, and the control unit controls the supply of power to the first solenoid to block communication between the reservoir and the first input port, and when the hydraulic pressure in the first hydraulic chamber becomes equal to or greater than the determination hydraulic pressure while the first electric cylinder is operating, the control unit controls the supply of power to the first solenoid to connect the reservoir and the first input port.

6. The braking device according to claim 5, wherein, when the braking request has been generated and the reservoir and the first input port are in communication by controlling the supply of power to the first solenoid, the control unit blocks the communication between the reservoir and the first input port by controlling the supply of power to the first solenoid when the first input port is blocked by the first piston.

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