Brake system

Abstract

Provided is a brake system (1) wherein a first brake system (50) is provided with a first main hydraulic pressure path (51), and a second brake system (60) is provided with a second main hydraulic pressure path (61). A first connecting hydraulic pressure path (71) leads from the first main hydraulic pressure path (51) to the second main hydraulic pressure path (61), and a second connecting hydraulic pressure path (72) leads from the second main hydraulic pressure path (61) to the first main hydraulic pressure path (51). When not energized, a first switching valve (56) causes the first main hydraulic pressure path (51) and the first connecting hydraulic pressure path (71) to communicate with each other. When non energized, a second switching valve (66) allows the second main hydraulic pressure path (61) and the second connecting hydraulic pressure path (72) to communicate with each other. In this configuration, even when one brake unit is not actuated, hydraulic braking pressure can be generated in both brake units.

Description

Technical Field

[0001] The present invention relates to a braking system.

Background Art

[0002] As a braking system, there is one that has a hydraulic pressure generating device that drives an electric motor according to the stroke amount of a brake pedal to generate brake hydraulic pressure, and two brake systems connected to the hydraulic pressure generating device, and applies brake hydraulic pressure from one hydraulic pressure generating device to the two brake systems (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] From the viewpoint of fail-safe and the like, as shown in FIG. 8, a braking system 100 is desired that includes two brake units 10 and 20 each having a hydraulic pressure generating device 12, 22, a brake system 50, 60, and an electronic control device 14, 24, and independently controls both brake units 10 and 20. In such a braking system 100, when the electronic control device or the hydraulic pressure generating device of one brake unit 10 does not operate, braking force is obtained only by the two wheel brakes B2 and B4 connected to the other brake unit 20.

[0005] An object of the present invention is to solve the above-described problems and provide a braking system capable of generating brake hydraulic pressure in both brake units even when the electronic control device or the hydraulic pressure generating device of one of the two brake units does not operate.

Means for Solving the Problems

[0006] To solve the aforementioned problems, the present invention provides a brake system comprising a first brake unit, a second brake unit, a first connecting hydraulic pressure passage and a second connecting hydraulic pressure passage connecting the first brake unit and the second brake unit. The first brake unit includes a first hydraulic pressure generator that generates brake fluid pressure according to the amount of operation of a brake lever, a first brake system, and a first electronic control device that controls the first hydraulic pressure generator and the first brake system. The first brake system includes a first main hydraulic pressure passage from the first hydraulic pressure generator to the first wheel brake, a third main hydraulic pressure passage from the first main hydraulic pressure passage to the third wheel brake, and a first switching valve provided in the first main hydraulic pressure passage. The second brake unit includes a second hydraulic pressure generator that generates brake fluid pressure according to the amount of operation of the brake lever, a second brake system, and a second electronic control device that controls the second hydraulic pressure generator and the second brake system. The second brake system comprises a second main hydraulic passage from the second hydraulic pressure generator to the second wheel brake, a fourth main hydraulic passage from the second main hydraulic passage to the fourth wheel brake, and a second switching valve provided in the second main hydraulic passage. The first connecting hydraulic passage extends from the first main hydraulic passage to the second main hydraulic passage, and the second connecting hydraulic passage extends from the second main hydraulic passage to the first main hydraulic passage. When energized, the first switching valve connects the first hydraulic pressure generator side and the first wheel brake side of the first main hydraulic passage, while the first main hydraulic passage and the first connecting hydraulic passage are not connected. When not energized, the first switching valve does not connect the first hydraulic pressure generator side and the first wheel brake side of the first main hydraulic passage, while the first main hydraulic passage and the first connecting hydraulic passage are connected. When energized, the second switching valve connects the second hydraulic pressure generator side of the second main hydraulic pressure passage to the second wheel brake side, while the second main hydraulic pressure passage and the second connecting hydraulic pressure passage are not connected. When not energized, the second switching valve connects the second hydraulic pressure generator side of the second main hydraulic pressure passage to the second wheel brake side, while the second main hydraulic pressure passage and the second connecting hydraulic pressure passage are connected.

[0007] In the brake system of the present invention, when the first switching valve is energized and the second switching valve is de-energized, the brake fluid pressure generated by the first hydraulic pressure generator is transmitted to the first main hydraulic pressure path and also transmitted from the second connecting hydraulic pressure path to the second main hydraulic pressure path via the second switching valve. This allows braking force to be generated on both the wheel brakes of the first brake unit and the wheel brakes of the second brake unit, even if the second electronic control unit or the second hydraulic pressure generator of the second brake unit is not operating.

[0008] Furthermore, in the brake system of the present invention, when the second switching valve is energized and the first switching valve is de-energized, the brake fluid pressure generated by the second hydraulic pressure generator is transmitted to the second main hydraulic pressure path, and also transmitted from the first connecting hydraulic pressure path through the first switching valve to the first main hydraulic pressure path. This allows braking force to be generated on both the wheel brakes of the second brake unit and the wheel brakes of the first brake unit, even if the first electronic control device or the first hydraulic pressure generator of the first brake unit is not operating.

[0009] Thus, in the brake system of the present invention, even if the electronic control device or hydraulic pressure generator of one of the two brake units is not operating, brake fluid pressure can be applied to the wheel brakes connected to both brake units.

[0010] In the aforementioned brake system, if the third main hydraulic passage is connected to the first main hydraulic passage on the side of the first hydraulic generator rather than the first switching valve, and the second switching valve is energized and the first switching valve is de-energized, the brake fluid pressure generated by the second hydraulic generator is transmitted from the first connecting hydraulic passage through the first switching valve to the first wheel brake side of the first main hydraulic passage. As a result, when the first electronic control device or the first hydraulic generator of the first brake unit is not operating, braking force is generated in the three wheel brakes: the first wheel brake, the second wheel brake, and the fourth brake. Furthermore, in the aforementioned brake system, if the fourth main hydraulic passage is connected to the second main hydraulic passage on the second hydraulic generator side of the second switching valve, and the first switching valve is energized and the second switching valve is de-energized, the brake fluid pressure generated by the first hydraulic generator is transmitted from the second connecting hydraulic passage through the second switching valve to the second wheel brake side of the second main hydraulic passage. As a result, when the second electronic control unit or the second hydraulic generator of the second brake unit is not operating, braking force is generated in the three wheel brakes: the first wheel brake, the second wheel brake, and the third brake. In the above configuration, the brake fluid pressure transmitted to the three wheel brakes can be increased compared to the case where the brake fluid pressure generated by the hydraulic pressure generator of one brake unit is transmitted to the four wheel brakes.

[0011] In the aforementioned braking system, it is preferable that the first wheel brake and the second wheel brake be provided on the left and right front wheels, respectively. In the above configuration, even if the electronic control device or hydraulic pressure generator of one of the brake units fails to operate, braking force is generated in the wheel brakes of both the left and right front wheels, allowing the vehicle to be stabilized and braked with a large braking force.

[0012] In the brake system described above, it is preferable that the first brake system includes a first inlet valve for opening and closing the first main hydraulic passage, a first return passage from the first main hydraulic passage to a first reservoir tank, and a first outlet valve for opening and closing the first return passage. Furthermore, it is preferable that the second brake system includes a second inlet valve for opening and closing the second main hydraulic passage, a second return passage from the second main hydraulic passage to a second reservoir tank, and a second outlet valve for opening and closing the second return passage.

[0013] In this configuration, opening the inlet valve and closing the outlet valve allows the brake fluid pressure generated by the hydraulic pressure generator to be transmitted to the wheel brakes (during normal braking or when the pressure is increased in anti-lock brake control). Conversely, closing the inlet valve and opening the outlet valve reduces the brake fluid pressure transmitted to the wheel brakes (when the pressure is reduced in anti-lock brake control). Furthermore, closing both the inlet and outlet valves maintains the brake fluid pressure transmitted to the wheel brakes (when the pressure is maintained in anti-lock brake control).

[0014] In the aforementioned brake system, it is preferable to simplify and miniaturize the fluid passage structure of the brake system by providing the first switching valve between the first inlet valve and the first return fluid passage, and the second switching valve between the second inlet valve and the second return fluid passage.

[0015] In the aforementioned brake system, it is preferable to set the drive amount of the first hydraulic pressure generator to be greater when the second switching valve is de-energized than when the second switching valve is energized. Furthermore, it is preferable to set the drive amount of the second hydraulic pressure generator to be greater when the first switching valve is de-energized than when the first switching valve is energized. Furthermore, it is preferable to set the first hydraulic pressure generator to increase the drive amount based on the required amount of fluid when the second switching valve is not energized. Also, it is preferable to set the second hydraulic pressure generator to increase the drive amount based on the required amount of fluid when the first switching valve is not energized.

[0016] In this configuration, even if the electronic control unit or hydraulic pressure generator of one brake unit fails to operate, the hydraulic pressure generator of the other brake unit alone can provide the wheel brakes connected to both brake units with the same brake fluid pressure as under normal conditions.

[0017] In the aforementioned brake system, if the first switching valve and the second switching valve are configured as three-way valves, the number of solenoid valves can be reduced while connecting two brake systems.

[0018] In the aforementioned brake system, the first hydraulic pressure generator and the second hydraulic pressure generator are configured to generate brake fluid pressure by moving a piston within a cylinder using an electric motor. The first main hydraulic pressure passage is connected to the cylinder of the first hydraulic pressure generator, and the second main hydraulic pressure passage is connected to the cylinder of the second hydraulic pressure generator. During normal brake operation, brake fluid pressure is supplied from the first hydraulic pressure generator to the first wheel brake and the third wheel brake, and from the second hydraulic pressure generator to the second wheel brake and the fourth wheel brake.

[0019] In the brake system described above, the first electronic control unit may be configured to switch between energized and de-energized states of the second switching valve, and the second electronic control unit may be configured to switch between energized and de-energized states of the first switching valve. Furthermore, the first electronic control unit may be configured to switch between energized and de-energized states of the second switching valve based on the detection of operation of the second brake unit. The second electronic control unit may also be configured to switch between energized and de-energized states of the first switching valve based on the detection of operation of the first brake unit.

[0020] In this configuration, for example, if the first electronic control unit detects a malfunction in the second brake unit, the first electronic control unit can de-energize the second switching valve, thereby allowing brake fluid pressure to be supplied from the first hydraulic pressure generator to the wheel brakes of the second brake unit. Furthermore, if the second electronic control unit detects a malfunction in the first brake unit, the second electronic control unit can de-energize the first switching valve, thereby allowing brake fluid pressure to be applied from the second hydraulic pressure generator to the wheel brakes of the first brake unit. [Effects of the Invention]

[0021] In the braking system of the present invention, even when the electronic control device or the hydraulic pressure generating device of one of the two braking units does not operate, braking hydraulic pressure is applied to the wheel brakes connected to both braking units, and braking force can be obtained in a balanced manner.

Brief Description of the Drawings

[0022] [Figure 1] It is a configuration diagram showing a braking system according to an embodiment of the present invention. [Figure 2] It is a configuration diagram in the normal braking operation in the braking system according to an embodiment of the present invention. [Figure 3] It is a configuration diagram when the second electronic control device or the second hydraulic pressure generating device of the second braking unit does not operate in the braking system according to an embodiment of the present invention. [Figure 4] It is a configuration diagram when the first electronic control device or the first hydraulic pressure generating device of the first braking unit does not operate in the braking system according to an embodiment of the present invention. [Figure 5] It is a graph showing the change in the braking hydraulic pressure generated by the hydraulic pressure generating device in the braking system according to an embodiment of the present invention. [Figure 6] It is a configuration diagram when the second electronic control device or the second hydraulic pressure generating device of the second braking unit does not operate in the braking system according to another embodiment of the present invention. [Figure 7] It is a configuration diagram when the first electronic control device or the first hydraulic pressure generating device of the first braking unit does not operate in the braking system according to another embodiment of the present invention. [Figure 8] It is a configuration diagram showing a reference form of the braking system.

Embodiments for Carrying Out the Invention

[0023] Embodiments of the present invention will be described in detail with appropriate reference to the drawings. In this embodiment, the application of the brake system of the present invention to a four-wheeled vehicle will be described as an example. Brake system 1, as shown in Figure 1, is a by-wire type brake system that operates when the prime mover (such as an engine or electric motor) is started. Brake system 1 can be installed in hybrid vehicles that use a motor in conjunction with other power sources, electric vehicles and fuel cell vehicles that use only a motor as a power source, and vehicles that use only an engine (internal combustion engine) as a power source.

[0024] Brake system 1 comprises a first brake unit 10 to which the first wheel brake B1 and the third wheel brake B3 are connected, and a second brake unit 20 to which the second wheel brake B2 and the fourth wheel brake B4 are connected. In this embodiment, the first wheel brake B1 brakes the left front wheel FL, and the third wheel brake B3 brakes the right rear wheel RR. Furthermore, the second wheel brake B2 brakes the right front wheel FR, and the fourth wheel brake B4 brakes the left rear wheel RL. Thus, the brake system 1 of this embodiment has a brake structure with X-shaped piping. Furthermore, in this embodiment, electric brakes EB, which function as parking brakes, are provided on the left rear wheel RL and the right rear wheel RR, respectively.

[0025] The first brake unit 10 includes a first base 11, a first hydraulic pressure generator 12, a first brake system 50, a first reservoir tank 13, and a first electronic control device 14. The first base 11 is a metal block mounted on the vehicle. Multiple flow channels are formed inside the first base 11.

[0026] The first hydraulic pressure generator 12 is an electric actuator that generates brake fluid pressure according to the stroke amount (operation amount) of the brake pedal P (brake operator). The first hydraulic pressure generator 12 is attached to the first base 11. The first hydraulic pressure generator 12 generates brake fluid pressure by moving a piston 12b inside a cylinder 12c using an electric motor 12a as the drive source.

[0027] The first reservoir tank 13 is a container for supplying brake fluid to the first hydraulic pressure generator 12 and is attached to the first base 11. Brake fluid is supplied from the first reservoir tank 13 to the cylinder 12c of the first hydraulic pressure generator 12 through a passage in the first base 11.

[0028] The first brake system 50 includes a first main hydraulic passage 51, a third main hydraulic passage 52, and a first return hydraulic passage 53, all of which are formed within the first base body 11. The first main hydraulic passage 51 is a passage from the first hydraulic generator 12 to the wheel cylinder of the first wheel brake B1. The third main hydraulic passage 52 is a passage from the first main hydraulic passage 51 to the wheel cylinder of the third wheel brake B3. The first main hydraulic passage 51 is connected to the cylinder 12c of the first hydraulic generator 12, and brake fluid pressure is supplied from the first hydraulic generator 12 to the first main hydraulic passage 51 and the third main hydraulic passage 52.

[0029] The first return fluid passage 53 is a flow path from the first main hydraulic passage 51 and the third main hydraulic passage 52 to the first reservoir tank 13. The first return fluid passage 53 comprises a first branch fluid passage 54 branching from the first main hydraulic passage 51 and a third branch fluid passage 55 branching from the third main hydraulic passage 52. The first branch fluid passage 54 and the third branch fluid passage 55 merge to form a single fluid passage. In other words, the first return fluid passage 53 comprises the first branch fluid passage 54 and the third branch fluid passage 55, which communicate with the first main hydraulic passage 51 and the third main hydraulic passage 52, respectively, and a fluid passage from the confluence point of the first branch fluid passage 54 and the third branch fluid passage 55 to the first reservoir tank 13. Brake fluid released from the first wheel brake B1 and the third wheel brake B3 flows into the first return fluid passage 53. The brake fluid released into the first return fluid passage 53 is returned to the first reservoir tank 13 through the first return fluid passage 53.

[0030] In the first main hydraulic passage 51, a first switching valve 56 is provided on the side of the first hydraulic generator 12 that is closer to the branching point with the first return hydraulic passage 53. In this embodiment, the first switching valve 56 is composed of a solenoid valve which is a three-way valve with two positions and three ports. Each port of the first switching valve 56 is connected to the first hydraulic pressure generator 12 side of the first main hydraulic pressure passage 51, to the first wheel brake B1 side of the first main hydraulic pressure passage 51, and to the first connecting hydraulic pressure passage 71, which will be described later. Furthermore, the third main hydraulic passage 52 is connected to the first main hydraulic passage 51, which is on the side of the first hydraulic generator 12, rather than the first switching valve 56.

[0031] When energized, the first switching valve 56, as shown in Figure 2, connects the first hydraulic pressure generator 12 side of the first main hydraulic pressure passage 51 to the first wheel brake B1 side, while the first main hydraulic pressure passage 51 and the first connecting hydraulic pressure passage 71 are not connected. In a normally operating brake system 1, the first switching valve 56 is energized when performing normal brake control and anti-lock brake control. When the first switching valve 56 is not energized, as shown in Figure 1, the first main hydraulic pressure passage 51 does not connect to the first hydraulic pressure generator 12 side and the first wheel brake B1 side, while the first main hydraulic pressure passage 51 and the first connecting hydraulic pressure passage 71 are in communication. In addition to when the power supply to the brake system 1 is turned OFF, the power supply to the first switching valve 56 is stopped if the first hydraulic pressure generator 12 or the first electronic control device 14 is not operating normally.

[0032] In the first main hydraulic passage 51, a first inlet valve 51a is provided between the branching point of the third main hydraulic passage 52 and the first switching valve 56. The first inlet valve 51a is a normally open type solenoid valve that opens and closes the first main hydraulic passage 51. The first branch liquid passage 54 is equipped with a first outlet valve 54a. The first outlet valve 54a is a normally closed solenoid valve that opens and closes the first branch liquid passage 54.

[0033] In the third main hydraulic passage 52, a third inlet valve 52a is provided on the side of the first hydraulic generator 12 that is closer to the branching point with the third branch hydraulic passage 55. The third inlet valve 52a is a normally open type solenoid valve that opens and closes the third main hydraulic passage 52. A third outlet valve 55a is provided in the third branch liquid passage 55. The third outlet valve 55a is a normally closed solenoid valve that opens and closes the third branch liquid passage 55.

[0034] The first electronic control unit 14 has a housing that contains a control board and is attached to the first base unit 11. Based on information obtained from various sensors such as pressure sensors and stroke sensors, and pre-stored programs, the first electronic control unit 14 controls the operation of the first hydraulic pressure generator 12 and the opening and closing of each valve in the first brake system 50.

[0035] The first brake unit 10 is capable of performing anti-lock brake control. While anti-lock brake control is being performed, the first switching valve 56 is energized, and the first hydraulic pressure generator 12 side of the first main hydraulic pressure passage 51 is in communication with the first wheel brake B1 side. During normal brake operation and pressure boosting in anti-lock brake control, as shown in Figure 2, the first inlet valve 51a and the third inlet valve 52a are open, while the first outlet valve 54a and the third outlet valve 55a are closed. This allows the brake fluid pressure generated by the first hydraulic pressure generator 12 to be transmitted to the first wheel brake B1 and the third wheel brake B3. During pressure reduction in antilock brake control, the first inlet valve 51a and the third inlet valve 52a are energized and closed, while the first outlet valve 54a and the third outlet valve 55a are energized and opened. As a result, brake fluid is released from the first wheel brake B1 and the third wheel brake B3 into the first return fluid passage 53, reducing the brake fluid pressure transmitted to the first wheel brake B1 and the third wheel brake B3. During the holding phase of the anti-lock brake control, the first inlet valve 51a and the third inlet valve 52a are energized and closed, while the first outlet valve 54a and the third outlet valve 55a are closed. This maintains the brake fluid pressure transmitted to the first wheel brake B1 and the third wheel brake B3.

[0036] The second brake unit 20 has the same configuration as the first brake unit 10 described above, and includes a second base 21, a second hydraulic pressure generator 22, a second brake system 60, a second reservoir tank 23, and a second electronic control unit 24. The second hydraulic pressure generator 22 generates brake fluid pressure corresponding to the stroke amount of the brake pedal P by moving the piston 22b inside the cylinder 22c using an electric motor 22a.

[0037] The second brake system 60 includes a second main hydraulic passage 61 leading from the second hydraulic pressure generator 22 to the second wheel brake B2, and a fourth main hydraulic passage 62 leading from the second main hydraulic passage 61 to the fourth wheel brake B4. Furthermore, the second brake system 60 has a second return fluid passage 63 that leads from the second main hydraulic passage 61 and the fourth main hydraulic passage 62 to the second reservoir tank 23. The second return fluid passage 63 comprises a second branch fluid passage 64 branching from the second main hydraulic passage 61 and a fourth branch fluid passage 65 branching from the fourth main hydraulic passage 62. The second branch fluid passage 64 and the fourth branch fluid passage 65 merge to form a single fluid passage. In other words, the second return fluid passage 63 comprises the second branch fluid passage 64 and the fourth branch fluid passage 65, which communicate with the second main hydraulic passage 61 and the fourth main hydraulic passage 62, respectively, and a fluid passage leading from the confluence point of the second branch fluid passage 64 and the fourth branch fluid passage 65 to the second reservoir tank 23.

[0038] The second main hydraulic passage 61 is equipped with a second inlet valve 61a, and the second branch hydraulic passage 64 of the second return hydraulic passage 63 is equipped with a second outlet valve 64a. Furthermore, the fourth main hydraulic passage 62 is equipped with a fourth inlet valve 62a, and the fourth branch hydraulic passage 65 is equipped with a fourth outlet valve 65a. Similar to the first brake unit 10, the second brake unit 20 is capable of performing antilock brake control by having the second electronic control device 24 control the operation of the second hydraulic pressure generator 22 and the opening and closing of each valve in the second brake system 60.

[0039] In the second main hydraulic passage 61, a second switching valve 66 is provided on the side of the second hydraulic generator 22 that is closer to the branching point with the second branch hydraulic passage 64. Each port of the second switching valve 66 is connected to the second hydraulic power generator 22 side of the second main hydraulic passage 61, to the second wheel brake B2 side of the second main hydraulic passage 61, and to the second connecting hydraulic passage 72, which will be described later. Furthermore, the fourth main hydraulic passage 62 is connected to the second main hydraulic passage 61, which is on the second hydraulic generator 22 side of the second switching valve 66.

[0040] When energized, the second switching valve 66, as shown in Figure 2, connects the second hydraulic pressure generator 22 side of the second main hydraulic pressure passage 61 to the second wheel brake B2 side, while the second main hydraulic pressure passage 61 and the second connecting hydraulic pressure passage 72 are not connected. In a normally operating brake system 1, the second switching valve 66 is energized when performing normal brake control and anti-lock brake control. When the second switching valve 66 is not energized, as shown in Figure 1, the second main hydraulic passage 61 does not connect to the first hydraulic generator 12 side and the second wheel brake B2 side, while the second main hydraulic passage 61 connects to the second connecting hydraulic passage 72. In addition to when the power supply to the brake system 1 is turned OFF, the power supply to the second switching valve 66 is stopped if the second hydraulic generator 22 or the second electronic control unit 24 is not operating normally.

[0041] In the brake system 1 of this embodiment, a first connecting hydraulic passage 71 is provided, which extends from the first main hydraulic passage 51 to the second main hydraulic passage 61, and a second connecting hydraulic passage 72 extends from the second main hydraulic passage 61 to the first main hydraulic passage 51. One end of the first connecting hydraulic passage 71 is connected to the first switching valve 56. The other end of the first connecting hydraulic passage 71 is connected to the second main hydraulic passage 61 on the second wheel brake B2 side of the second switching valve 66. One end of the second connecting hydraulic passage 72 is connected to the second switching valve 66. The other end of the second connecting hydraulic passage 72 is in communication with the first main hydraulic passage 51 on the side of the first hydraulic generator 12 that is closer to the first switching valve 56. The first connecting hydraulic passage 71 and the second connecting hydraulic passage 72 are composed of flow paths within the first base 11 and the second base 21, and piping provided between the first base 11 and the second base 21.

[0042] In the brake system 1 of this embodiment, the drive amount of the first hydraulic pressure generator 12 is set to be greater when the second switching valve 66 is de-energized than when the second switching valve 66 is energized (see Figure 5). Specifically, the drive amount of the first hydraulic pressure generator 12 is controlled so that the amount of fluid (required fluid) supplied from the first hydraulic pressure generator 12 is equal to the amount of fluid supplied when the second switching valve 66 is de-energized so that the amount of fluid applied to each wheel brake (two wheel brakes in this embodiment) is equal to the amount of fluid applied to each wheel brake (three wheel brakes in this embodiment) when the second switching valve 66 is de-energized.

[0043] Furthermore, the drive amount of the second hydraulic pressure generator 22 is set to be greater when the first switching valve 56 is de-energized than when the first switching valve 56 is energized. Specifically, the drive amount of the second hydraulic pressure generator 22 is controlled so that the amount of fluid supplied from the second hydraulic pressure generator 22 is equal to the amount of fluid supplied when the first switching valve 56 is de-energized so that the amount of fluid supplied to each wheel brake (three wheel brakes in this embodiment) is equal to the amount of fluid supplied when the first switching valve 56 is de-energized.

[0044] Next, the brake control in the brake system 1 of this embodiment will be described. During normal brake operation, as shown in Figure 2, the first switching valve 56 of the first brake unit 10 is energized, and the second switching valve 66 of the second brake unit 20 is energized. As a result, the first hydraulic pressure generator 12 side and the first wheel brake B1 side of the first main hydraulic pressure passage 51 are connected. The brake fluid pressure generated by the first hydraulic pressure generator 12 is then transmitted to the first wheel brake B1 and also to the third wheel brake B3 via the third main hydraulic pressure passage 52. Furthermore, the second main hydraulic passage 61 is connected to the second hydraulic generator 22 side and the second wheel brake B2 side. The brake fluid pressure generated by the second hydraulic generator 22 is transmitted to the second wheel brake B2 and also to the fourth wheel brake B4 via the fourth main hydraulic passage 62. Thus, during normal braking, the first hydraulic pressure generator 12 generates braking force on the first wheel brake B1 and the third wheel brake B3, and the second hydraulic pressure generator 22 generates braking force on the second wheel brake B2 and the fourth wheel brake B4.

[0045] During normal braking, as shown in Figure 3, a malfunction may occur in the second brake unit 20, causing at least one of the second electronic control unit 24 and the second hydraulic pressure generator 22 to fail to operate, and the second switching valve 66 to become de-energized. In this case, the position of the second switching valve 66 returns to its initial state (de-energized state), so the second hydraulic pressure generator 22 side of the second main hydraulic pressure passage 61 does not communicate with the second wheel brake B2 side and the fourth wheel brake B4 side, while the second main hydraulic pressure passage 61 and the second connecting hydraulic pressure passage 72 communicate with each other. In this state, the brake fluid pressure generated by the first hydraulic pressure generator 12 is transmitted to the first wheel brake B1 and the third wheel brake B3, and is also transmitted to the second wheel brake B2 via the first main hydraulic pressure passage 51, the second connecting hydraulic pressure passage 72, the second switching valve 66, and the second main hydraulic pressure passage 61. Thus, even when the second electronic control unit 24 and the second hydraulic pressure generator 22 of the second brake unit 20 are not operating, the first hydraulic pressure generator 12 of the first brake unit 10 generates braking force on the first wheel brake B1, the second wheel brake B2, and the third wheel brake B3.

[0046] Furthermore, the amount of drive of the first hydraulic pressure generator 12 is greater when the second switching valve 66 is de-energized (when the second electronic control unit 24 and the second hydraulic pressure generator 22 are not operating) than when the second switching valve 66 is energized (during normal brake operation) (see Figure 5). As a result, even when the first hydraulic pressure generator 12 applies brake fluid pressure to the three wheel brakes B1, B2, and B3, the same brake fluid pressure as under normal conditions is applied to each wheel brake B1, B2, and B3.

[0047] During normal brake operation, as shown in Figure 4, a malfunction may occur in the first brake unit 10, causing at least one of the first electronic control unit 14 and the first hydraulic pressure generator 12 of the first brake unit 10 to fail to operate, resulting in the first switching valve 56 becoming de-energized. In this case, the position of the first switching valve 56 returns to its initial state (de-energized state), so the first hydraulic pressure generator 12 side and the first wheel brake B1 side of the first main hydraulic pressure passage 51 are not in communication, while the first main hydraulic pressure passage 51 and the first connecting hydraulic pressure passage 71 are in communication. In this state, the brake fluid pressure generated by the second hydraulic pressure generator 22 is transmitted to the second wheel brake B2 and the fourth wheel brake B4, and is also transmitted to the first wheel brake B1 via the second main hydraulic pressure passage 61, the first connecting hydraulic pressure passage 71, the first switching valve 56, and the first main hydraulic pressure passage 51. Thus, even when the first electronic control device 14 and the first hydraulic pressure generator 12 of the first brake unit 10 are not operating, braking force is generated in the first wheel brake B1, the second wheel brake B2, and the fourth wheel brake B4 by the second hydraulic pressure generator 22 of the second brake unit 20.

[0048] Furthermore, the amount of drive of the second hydraulic pressure generator 22 is greater when the first switching valve 56 is de-energized (when the first electronic control unit 14 and the first hydraulic pressure generator 12 are not operating) than when the first switching valve 56 is energized (during normal brake operation) (see Figure 5). As a result, even when the second hydraulic pressure generator 22 applies brake fluid pressure to the three wheel brakes B1, B2, and B4, the same brake fluid pressure as under normal conditions is applied to each wheel brake B1, B2, and B4.

[0049] In the brake system 1 described above, during normal braking, as shown in Figure 2, the first hydraulic pressure generator 12 applies brake fluid pressure to the first wheel brake B1 and the third wheel brake B3. Additionally, the second hydraulic pressure generator 22 applies brake fluid pressure to the second wheel brake B2 and the fourth wheel brake B4. In this way, the brake system 1 allows for independent control of both brake units 10 and 20.

[0050] In the brake system 1 of this embodiment, as shown in Figure 3, even if the second electronic control device 24 or the second hydraulic pressure generator 22 of the second brake unit 20 are not operating, brake fluid pressure can be applied to the second wheel brake B2 connected to the second brake unit 20. As a result, even if the second electronic control unit 24 or the second hydraulic pressure generator 22 of the second brake unit 20 are not operating, braking force can be generated in the three wheel brakes B1, B2, and B3. In particular, a large braking force is generated by the first wheel brake B1 and the second wheel brake B2, which are provided on both the left and right front wheels FL and FR, allowing the vehicle to be braked while remaining stable.

[0051] In the brake system 1 of this embodiment, as shown in Figure 4, even if the first electronic control device 14 or the first hydraulic pressure generator 12 of the first brake unit 10 are not operating, brake fluid pressure can be applied to the first wheel brake B1 connected to the first brake unit 10. As a result, even if the first electronic control unit 14 or the first hydraulic pressure generator 12 of the first brake unit 10 are not operating, braking force can be generated in the three wheel brakes B1, B2, and B4. In particular, since a large braking force is generated in the first wheel brake B1 and the second wheel brake B2, which are provided on both the left and right front wheels, the vehicle can be braked while remaining stable.

[0052] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from its spirit. In the brake system 1 of this embodiment, as shown in Figure 1, the third main hydraulic passage 52 is connected to the first main hydraulic passage 51 on the first hydraulic generator 12 side of the first switching valve 56, and the fourth main hydraulic passage 62 is connected to the second main hydraulic passage 61 on the second hydraulic generator 22 side of the second switching valve 66. However, as shown in the brake system 1A in Figure 6, the third main hydraulic passage 52 may be connected to the first main hydraulic passage 51 on the first wheel brake B1 side of the first switching valve 56, and the fourth main hydraulic passage 62 may be connected to the second main hydraulic passage 61 on the second wheel brake B2 side of the second switching valve 66.

[0053] In the aforementioned brake system 1A, as shown in Figure 6, when the second switching valve 66 is de-energized during normal brake operation, the brake fluid pressure generated by the first hydraulic pressure generator 12 is transmitted to the first wheel brake B1 and the third wheel brake B3, as well as to the second wheel brake B2 and the fourth wheel brake B4 via the first main hydraulic pressure passage 51, the second connecting hydraulic pressure passage 72, the second switching valve 66, the second main hydraulic pressure passage 61, and the fourth main hydraulic pressure passage 62. Thus, in the brake system 1A, even when the second electronic control device 24 and the second hydraulic pressure generator 22 of the second brake unit 20 are not operating, the first hydraulic pressure generator 12 of the first brake unit 10 generates braking force on the four wheel brakes B1, B2, B3, and B4.

[0054] Furthermore, in the aforementioned brake system 1A, as shown in Figure 7, when the first switching valve 56 is de-energized during normal brake operation, the brake fluid pressure generated by the second hydraulic pressure generator 22 is transmitted to the second wheel brake B2 and the fourth wheel brake B4, as well as to the first wheel brake B1 and the third wheel brake B3 via the second main hydraulic pressure passage 61, the first connecting hydraulic pressure passage 71, the first switching valve 56, the first main hydraulic pressure passage 51, and the third main hydraulic pressure passage 52. Thus, in the brake system 1A, even when the first electronic control device 14 and the first hydraulic pressure generator 12 of the first brake unit 10 are not operating, braking force is generated on the four wheel brakes B1, B2, B3, and B4 by the second hydraulic pressure generator 22 of the second brake unit 20.

[0055] In the brake system 1 of this embodiment, the first electronic control unit 14 shown in Figure 1 may be configured to detect the operating state of the second brake unit 20, and the second electronic control unit 24 may be configured to detect the operating state of the first brake unit 10. Furthermore, the first electronic control unit 14 may be configured to switch between energized and de-energized states of the second switching valve 66, and the second electronic control unit 24 may be configured to switch between energized and de-energized states of the first switching valve 56. In this configuration, the second switching valve 66 is not de-energized during normal brake operation. However, if the first electronic control unit 14 detects a malfunction in the operation of the second brake unit 20, the first electronic control unit 14 de-energizes the second switching valve 66, thereby allowing brake fluid pressure to be supplied from the first hydraulic pressure generator 12 to the second wheel brake B2 of the second brake unit 20. Furthermore, even if the first switching valve 56 is not de-energized during normal brake operation, if the second electronic control unit 24 detects a malfunction in the operation of the first brake unit 10, the second electronic control unit 24 de-energizes the first switching valve 56, thereby allowing brake fluid pressure to be applied from the second hydraulic pressure generator 22 to the first wheel brake B1 of the first brake unit 10.

[0056] In the brake system 1 of this embodiment, the first switching valve 56 and the second switching valve 66 are configured as three-way valves, but a single switching valve may be configured by combining multiple solenoid valves. [Explanation of Symbols]

[0057] 1. Brake System 1A Brake system (other embodiments) 10 First Brake Unit 11 First base 12. First hydraulic pressure generator 12a electric motor 12b Piston 12c cylinder 13. First reservoir tank 14 First Electronic Control Unit 20 Second brake unit 21 Second base 22 Second hydraulic pressure generator 22a Electric motor 22b Piston 22c cal 23 Second reservoir tank 24 Second Electronic Control Unit 50 First Brake System 51 First Main Hydraulic Circuit 51a First inlet valve 52 Third Main Hydraulic Circuit 52a Third inlet valve 53 First return fluid channel 54 First branch liquid channel 54a First outlet valve 55 Third branch liquid channel 55a Third outlet valve 56 First switching valve 60 Second braking system 61 Second main hydraulic circuit 61a Second inlet valve 62 Fourth Main Hydraulic Circuit 63 Second return fluid channel 64 Second branch liquid channel 64a Second outlet valve 65 Fourth branch liquid channel 65a Fourth outlet valve 66 Second switching valve 71 First connecting hydraulic circuit 72 Second connecting hydraulic circuit B1 First Wheel Brake B2 Second Wheel Brake B3 Third Wheel Brake B4 Fourth Wheel Brake FL left front wheel FR Right front wheel RL (Left rear wheel) RR Right rear wheel P Brake pedal EB electric brake

Claims

1. A brake system comprising a first brake unit, a second brake unit, and a first connecting hydraulic passage and a second connecting hydraulic passage connecting the first brake unit and the second brake unit, The aforementioned first brake unit is A first hydraulic pressure generator that generates brake fluid pressure according to the amount of operation of the brake lever, First braking system, The system includes the first hydraulic pressure generator and the first electronic control unit that controls the first brake system, The aforementioned first brake system is The first main hydraulic circuit extends from the first hydraulic pressure generator to the first wheel brake, A third main hydraulic passage extends from the first main hydraulic passage to the third wheel brake, The system includes a first switching valve provided in the first main hydraulic passage, The aforementioned second brake unit is A second hydraulic pressure generator that generates brake fluid pressure according to the amount of operation of the brake lever, Second braking system and The system includes the second hydraulic pressure generator and the second electronic control unit that controls the second brake system, The aforementioned second braking system is The second main hydraulic path from the second hydraulic pressure generator to the second wheel brake, The fourth main hydraulic passage extends from the second main hydraulic passage to the fourth wheel brake, The second main hydraulic passage is provided with a second switching valve, The first connecting hydraulic passage extends from the first main hydraulic passage to the second main hydraulic passage. The second connecting hydraulic passage extends from the second main hydraulic passage to the first main hydraulic passage. When energized, the first switching valve is in a state where the first hydraulic pressure generator side and the first wheel brake side of the first main hydraulic pressure passage are in communication, and the first main hydraulic pressure passage and the first connecting hydraulic pressure passage are not in communication. When the first switching valve is not energized, the first main hydraulic pressure passage does not communicate with the first hydraulic pressure generator side and the first wheel brake side, while the first main hydraulic pressure passage and the first connecting hydraulic pressure passage communicate with each other. When energized, the second switching valve is in a state where the second hydraulic pressure generator side of the second main hydraulic pressure passage and the second wheel brake side are in communication, and the second main hydraulic pressure passage and the second connecting hydraulic pressure passage are not in communication. A brake system characterized in that, when the second switching valve is not energized, the second main hydraulic pressure passage does not communicate with the second hydraulic pressure generator side and the second wheel brake side, while the second main hydraulic pressure passage and the second connecting hydraulic pressure passage communicate with each other.

2. A brake system according to claim 1, The third main hydraulic passage is connected to the first main hydraulic passage on the side of the first hydraulic generator that is closer to the first switching valve. A brake system characterized in that the fourth main hydraulic passage is in communication with the second main hydraulic passage on the side of the second hydraulic generator rather than the second switching valve.

3. A brake system according to claim 1, A braking system characterized in that the first wheel brake and the second wheel brake are provided on the left and right front wheels, respectively.

4. A brake system according to claim 1, The aforementioned first brake system is A first inlet valve that opens and closes the first main hydraulic passage, The first return fluid passage from the first main fluid pressure passage to the first reservoir tank, The system includes a first outlet valve that opens and closes the first return fluid passage, The aforementioned second braking system is A second inlet valve that opens and closes the second main hydraulic passage, The second return fluid passage from the second main fluid pressure passage to the second reservoir tank, A brake system characterized by comprising a second outlet valve that opens and closes the second return fluid passage.

5. A brake system according to claim 4, The first switching valve is provided between the first inlet valve and the first return fluid passage. A brake system characterized in that the second switching valve is provided between the second inlet valve and the second return fluid passage.

6. A brake system according to claim 1, The drive amount of the first hydraulic pressure generator is, The second switching valve is set to be larger when it is not energized than when it is energized. The drive amount of the second hydraulic pressure generator is, A brake system characterized in that the value is set such that the value is greater when the first switching valve is not energized than when the first switching valve is energized.

7. A brake system according to claim 6, The first hydraulic pressure generating device is set to increase the drive amount based on the required amount of fluid when the second switching valve is not energized. The brake system is characterized in that the second hydraulic pressure generating device is set to increase the drive amount based on the required amount of fluid when the first switching valve is not energized.

8. A brake system according to claim 1, A brake system characterized in that the first switching valve and the second switching valve are composed of three-way valves.

9. A brake system according to claim 1, The first hydraulic pressure generating device and the second hydraulic pressure generating device are configured to generate brake fluid pressure by moving a piston within a cylinder using an electric motor. The first main hydraulic passage is connected to the cylinder of the first hydraulic pressure generating device. A brake system characterized in that the second main hydraulic passage is connected to the cylinder of the second hydraulic pressure generating device.

10. A brake system according to claim 1, The first electronic control device is capable of switching between energized and de-energized states of the second switching valve, The brake system is characterized in that the second electronic control device can switch between energized and de-energized states of the first switching valve.

11. A brake system according to claim 10, The first electronic control unit switches the energized state and the de-energized state of the second switching valve based on the detection of the operation of the second brake unit, The brake system is characterized in that the second electronic control unit switches between energized and de-energized states of the first switching valve based on the detection of operation of the first brake unit.

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