Braking system

Abstract

A braking system 30 comprises: two front wheel braking units 41FL, 41FR that are provided corresponding to respective two wheel cylinders 21 and that adjust hydraulic pressure of the corresponding wheel cylinders 21; a switching unit 43 that is switchable between a communication state in which the two wheel cylinders 21 communicate with each other and a cut-off state in which the communication between the two wheel cylinders 21 is cut off; two rear wheel braking units 60RL, 60RR that are provided corresponding to respective two rear wheels 11RL, 11RR and that adjust braking force generated at the corresponding rear wheels 11RL, 11RR; a first power supply 71 that supplies power to the front wheel braking unit 41FL and the rear wheel braking unit 60RR; and a second power supply 72 that supplies power to the front wheel braking unit 41FR and the rear wheel braking unit 60RL.

Description

Brake system

[0001] The present invention relates to a brake system provided in a vehicle.

[0002] Patent Document 1 discloses a brake system including a plurality of braking units corresponding to each of a plurality of wheels. The plurality of braking units include electric motors driven by power supplied from a battery. The plurality of braking units generate a braking force corresponding to the driving of the electric motor on the corresponding wheel.

[0003] Japanese Patent Application Laid-Open No. 2000-110865

[0004] In the brake system as described above, redundancy is required.

[0005] The brake system for solving the above problems is provided in a vehicle including two first wheels and two second wheels, and in the two first wheels, a braking force corresponding to the hydraulic pressure of the corresponding wheel cylinder is generated. The brake system includes two braking units provided corresponding to each of the two wheel cylinders and electrically adjusting the hydraulic pressure of the corresponding wheel cylinder, and a hydraulic brake device having a switching unit capable of switching between a communicating state in which the two wheel cylinders are communicated and a blocking state in which the communication between the two wheel cylinders is blocked, and two braking units provided corresponding to each of the two second wheels and electrically adjusting the braking force generated on the corresponding second wheel, a first power source for supplying power to two first braking units which are specific braking units among the four braking units, and a second power source for supplying power to two second braking units which are braking units other than the first braking units among the four braking units.

[0006] The above brake system has an effect that even when one of the two power sources cannot supply power, the vehicle can generate a braking force.

[0007] Figure 1 is a schematic diagram showing a vehicle equipped with the braking system of the first embodiment. Figure 2 is a schematic diagram showing the front wheel braking section of the braking system of Figure 1. Figure 3 is a flowchart showing a series of processes for selecting a braking mode in the braking system of Figure 1. Figure 4 is an operation diagram showing what happens when an abnormality occurs in the second power supply in the braking system of Figure 1. Figure 5 is a schematic diagram showing a vehicle equipped with the braking system of the second embodiment. Figure 6 is a schematic diagram showing a vehicle equipped with the braking system of the third embodiment. Figure 7 is a schematic diagram showing a vehicle equipped with the braking system of the fourth embodiment.

[0008] (First Embodiment) A first embodiment of the braking system will be described with reference to Figures 1 to 4. <Overall Vehicle Configuration> Figure 1 shows a vehicle 10 on which the braking system 30 is installed. The vehicle 10 is equipped with a left front wheel 11FL, a right front wheel 11FR, a left rear wheel 11RL, and a right rear wheel 11RR. In this embodiment, the two front wheels 11FL and 11FR correspond to the "first wheels," and the two rear wheels 11RL and 11RR correspond to the "second wheels."

[0009] Vehicle 10 is equipped with two friction brakes 20FL and 20FR for the front wheels. Friction brake 20FL corresponds to the left front wheel 11FL. Friction brake 20FR corresponds to the right front wheel 11FR. Each of the multiple friction brakes 20FL and 20FR is configured to generate braking force on the corresponding front wheels 11FL and 11FR by pressing a friction material against a rotating body that rotates integrally with the respective front wheels 11FL and 11FR. Each of the multiple friction brakes 20FL and 20FR has a wheel cylinder 21. The higher the braking pressure, which is the hydraulic pressure of the wheel cylinder 21, the greater the braking force generated on the front wheels 11FL and 11FR.

[0010] <Configuration of the braking system> The braking system 30 comprises a hydraulic braking device 40, two rear wheel braking units 60RL and 60RR, a first power supply 71, a second power supply 72, and a control device 80.

[0011] The hydraulic braking system 40 is equipped with two front wheel braking units 41FL and 41FR. Front wheel braking unit 41FL is a braking unit that electrically adjusts the braking pressure of the wheel cylinder 21 of the friction brake 20FL corresponding to the left front wheel 11FL. Front wheel braking unit 41FR is a braking unit that electrically adjusts the braking pressure of the wheel cylinder 21 of the friction brake 20FR corresponding to the right front wheel 11FR. Front wheel braking units 41FL and 41FR are in communication with the wheel cylinders 21 via a supply passage, which is a flow path for brake fluid. Hereafter, the supply passage connecting the front wheel braking unit 41FL and the wheel cylinder 21 of the friction brake 20FL will be referred to as "supply passage 42FL", and the supply passage connecting the front wheel braking unit 41FR and the wheel cylinder 21 of the friction brake 20FR will be referred to as "supply passage 42FR".

[0012] Figure 2 illustrates an example of a front wheel braking unit 41FL, 41FR. Multiple front wheel braking units 41FL, 41FR have an electric cylinder 50 as a source of brake fluid to the wheel cylinder 21. The electric cylinder 50 includes a cylinder 51, a piston 52, an electric motor 53, and a conversion mechanism 54. The piston 52 is provided in a slidable state within the cylinder 51. The conversion mechanism 54 converts the rotation of the output shaft of the electric motor 53 into the linear movement of the piston 52.

[0013] Inside the cylinder 51, a hydraulic chamber Re for storing brake fluid is partitioned by the peripheral wall of the cylinder 51 and the piston 52. The position of the piston 52 inside the cylinder 51 can be changed by driving the electric motor 53. Hereafter, the direction of linear movement of the piston 52 when reducing the volume of the hydraulic chamber Re will be described as the "forward direction Za," and 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 52 when increasing the volume of the hydraulic chamber Re.

[0014] The cylinder 51 has an output port 51P that connects the hydraulic chamber Re to the outside. The output port 51P is always open. Supply lines 42FL and 42FR are connected to the output port 51P.

[0015] When the electric motor 53 is driven, the motor rotation angle, which is the rotation angle of the electric motor 53's rotating shaft, increases, causing the piston 52 to move in the forward direction Za. As a result, brake fluid from the hydraulic chamber Re is discharged through the output port 51P to the supply passages 42FL and 42FR. This supplies brake fluid to the wheel cylinder 21, increasing the braking pressure. On the other hand, when the electric motor 53 is driven and the motor rotation angle decreases, the piston 52 moves in the backward direction Zb. As a result, brake fluid from the supply passages 42FL and 42FR flows into the hydraulic chamber Re through the output port 51P. This causes brake fluid to flow out of the wheel cylinder 21, decreasing the braking pressure.

[0016] As shown in Figure 1, the hydraulic braking device 40 is equipped with a switching unit 43 that can switch between a connected state in which the two wheel cylinders 21 are in communication and a blocked state in which the communication between the two wheel cylinders 21 is blocked. For example, the switching unit 43 is equipped with a communication passage 44 and a shut-off valve 45 installed in the communication passage 44. The communication passage 44 is a flow path for brake fluid connecting the supply passage 42FL and the supply passage 42FR. An example of a shut-off valve 45 is a normally open solenoid valve. When no power is supplied to the solenoid of the shut-off valve 45, the shut-off valve 45 opens, and the two supply passages 42FL and 42FR are in communication via the communication passage 44. On the other hand, when power is supplied to the solenoid of the shut-off valve 45, the shut-off valve 45 closes, and the communication between the two supply passages 42FL and 42FR via the communication passage 44 is blocked. Therefore, the state of the switching unit 43 when the shut-off valve 45 is open is the connected state. On the other hand, the state in which the shut-off valve 45 is closed in the switching section 43 is the shut-off state.

[0017] The rear wheel braking unit 60RL is provided in correspondence with the left rear wheel 11RL and is a braking unit that electrically adjusts the braking force generated by the left rear wheel 11RL. The rear wheel braking unit 60RR is provided in correspondence with the right rear wheel 11RR and is a braking unit that electrically adjusts the braking force generated by the right rear wheel 11RR. The rear wheel braking units 60RL and 60RR are electric braking devices powered by an electric motor 61. When the rotation angle of the output shaft of the electric motor 61 in the rear wheel braking units 60RL and 60RR increases, the braking force generated by the corresponding rear wheels 11RL and 11RR increases. On the other hand, when the rotation angle of the output shaft decreases, the braking force generated by the corresponding rear wheels 11RL and 11RR decreases. For example, the electric braking device disclosed in "Japanese Patent Publication No. 2024-108148" can be cited as the rear wheel braking units 60RL and 60RR.

[0018] The first power supply 71 and the second power supply 72 are power supplies for the hydraulic braking system 40 and the rear wheel braking units 60RL and 60RR. The first power supply 71 supplies power to two specific first braking units among the two front wheel braking units 41FL and 41FR and the two rear wheel braking units 60RL and 60RR. The second power supply 72 supplies power to two second braking units other than the two first braking units among the two front wheel braking units 41FL and 41FR and the two rear wheel braking units 60RL and 60RR.

[0019] In the braking system 30, the first power supply 71 supplies power to the front wheel braking section 41FL and the rear wheel braking section 60RR. On the other hand, the first power supply 71 does not supply power to the front wheel braking section 41FR and the rear wheel braking section 60RL. The second power supply 72 supplies power to the front wheel braking section 41FR and the rear wheel braking section 60RL. On the other hand, the second power supply 72 does not supply power to the front wheel braking section 41FL and the rear wheel braking section 60RR. In other words, the front wheel braking section 41FL and the rear wheel braking section 60RR correspond to the "first braking section". The front wheel braking section 41FR and the rear wheel braking section 60RL correspond to the "second braking section".

[0020] Both the first power supply 71 and the second power supply 72 are capable of supplying power to the switching unit 43. Therefore, even if one of the power supplies, the first power supply 71 or the second power supply 72, becomes unable to supply power, the switching unit 43 can still be driven by power supplied from the other power supply.

[0021] The control device 80 receives detection signals from multiple sensors. These multiple sensors include a brake sensor 101 that detects the amount of operation of the driver's brake operating member 15 of the vehicle 10. Based on these detection signals from multiple sensors, the control device 80 controls the two front wheel braking units 41FL, 41FR and the two rear wheel braking units 60RL, 60RR and the switching unit 43 of the braking system 30.

[0022] The control device 80 includes a processing circuit. An example of a processing circuit is an electronic control device. In this case, the processing circuit includes a CPU and a memory that stores a control program executed by the CPU. The CPU executes the control program in the memory, thereby allowing the processing circuit of the control device 80 to control the braking system 30.

[0023] The control device 80 provides two braking modes for controlling the braking force Fx of the vehicle 10: a normal braking mode and a three-wheel braking mode. The normal braking mode is a braking mode in which the two front wheel braking units 41FL, 41FR and the two rear wheel braking units 60RL, 60RR are activated with the switching unit 43 in a closed state. When controlling the braking force Fx of the vehicle 10 in the normal braking mode, the control device 80 can generate braking force with all four wheels 11FL, 11FR, 11RL, and 11RR.

[0024] The three-wheel braking mode is a braking mode in which the switching unit 43 is set to a connected state, and one of the two front wheel braking units 41FL and 41FR and one of the two rear wheel braking units 60RL and 60RR are activated. When controlling the braking force Fx of the vehicle 10 in three-wheel braking mode, the control device 80 can generate braking force on all three wheels.

[0025] <Braking Mode Selection Process> Referring to Figure 3, a series of processes performed by the control device 80 when selecting a braking mode will be explained. This series of processes is the braking mode selection process.

[0026] In step S11, the control device 80 determines whether only one of the first power supply 71 and the second power supply 72 is abnormal. Here, "abnormal power supply" includes a state in which power cannot be supplied to the power supply target, and a state in which there is a possibility that power cannot be supplied to the power supply target. For example, the control device 80 determines that an abnormal power supply has occurred if at least one of the following multiple conditions is met. In this case, the control device 80 determines that no abnormal power supply has occurred if none of the multiple conditions are met.

[0027] - The power supply voltage is below the specified voltage. - Even when the braking unit is activated, no braking force is generated in the wheel corresponding to that braking unit. - The power supply line connecting the power supply to the power source and the power supply itself is broken.

[0028] The specified voltage is the minimum voltage or a power slightly higher than the minimum voltage required to operate the braking unit normally. In step S11, if the control device 80 determines that only one of the first power supply 71 and the second power supply 72 is abnormal (S11: YES), the control device 80 proceeds to step S13. On the other hand, if the control device 80 determines that neither the first power supply 71 nor the second power supply 72 is abnormal (S11: NO), the control device 80 proceeds to step S15. In other words, if both the first power supply 71 and the second power supply 72 are normal, the control device 80 proceeds to step S15.

[0029] In step S13, the control device 80 selects the three-wheel braking mode as the braking mode. The control device 80 then terminates the braking mode selection process. In step S15, the control device 80 selects the normal braking mode as the braking mode. The control device 80 then terminates the braking mode selection process.

[0030] <Operation when the 3-wheel braking mode is selected> Referring to Figure 4, for example, the case in which only the second power supply 72 of the two power supplies 72, of which the first power supply 71 is abnormal will be explained. In this case, as shown by arrow Y1 in Figure 4, the first power supply 71 can supply power to the front wheel braking unit 41FL for the left front wheel 11FL, the rear wheel braking unit 60RR for the right rear wheel 11RR, and the switching unit 43. Therefore, the control device 80 puts the switching unit 43 into a communication state. Then, the control device 80 operates the front wheel braking unit 41FL. In this case, since the two wheel cylinders 21 are in communication via the communication passage 44, as shown by arrow Y2 in Figure 4, the brake fluid supplied from the front wheel braking unit 41FL is supplied to the two wheel cylinders 21. As a result, when the front wheel braking unit 41FL is operated, braking force is generated in both of the two front wheels 11FL and 11FR.

[0031] Furthermore, the control device 80 can generate braking force at the right rear wheel 11RR by activating the rear wheel braking unit 60RR. Therefore, the control device 80 can generate braking force at three wheels, namely the left front wheel 11FL, the right front wheel 11FR, and the right rear wheel 11RR.

[0032] Furthermore, even if an abnormality occurs only in the first power supply 71 of the two power supplies 72, the control device 80 can still generate braking force on all three wheels. The processing flow in this case is substantially the same as when an abnormality occurs only in the second power supply 72, so a detailed explanation will be omitted. In this case, the control device 80 can generate braking force on the left front wheel 11FL, the right front wheel 11FR, and the left rear wheel 11RL.

[0033] <Effects of this embodiment> (1-1) In the braking system 30, if an abnormality occurs in only one of the first power supply 71 and the second power supply 72, power can be supplied from the other power supply to two of the four braking units. Therefore, the braking system 30 can generate a braking force Fx in the vehicle 10 even if one of the two power supplies 71 and 72 is unable to supply power.

[0034] (1-2) Even if an abnormality occurs in only one of the first power supply 71 and the second power supply 72, if one of the two front wheel braking units 41FL, 41FR is operational, the braking system 30 can generate braking force in both front wheels 11FL, 11FR by operating the one front wheel braking unit after connecting the switching unit 43.

[0035] (1-3) The two front wheel braking units 41FL and 41FR each include one of the two first braking units and one of the two second braking units. Furthermore, the two rear wheel braking units 60RL and 60RR each include the remaining one of the two first braking units and the remaining one of the two second braking units. Therefore, even if a malfunction occurs in only one of the first power supply units 71 and the second power supply unit 72, the hydraulic braking device 40 can generate braking force on the two front wheels 11FL and 11FR, and one of the two rear wheel braking units 60RL and 60RR can operate. Thus, the braking system 30 can generate braking force on all three wheels even if only one of the first power supply units 71 and the second power supply unit 72 malfunctions.

[0036] (1-4) The two wheels that are the targets of the braking force generated by the hydraulic braking device 40 include the right front wheel 11FR and the left front wheel 11FL. Therefore, even if an abnormality occurs in only one of the first power supply 71 and the second power supply 72, the braking system 30 can generate braking force on one of the two right wheels 11FR and 11RR and one of the two left wheels 11FL and 11RL by setting the state of the switching unit 43 to a communication state.

[0037] Furthermore, the first power supply 71 and the second power supply 72 can supply power to one of the braking units provided on the right wheels 11FR and 11RR, and to one of the braking units provided on the left wheels 11FL and 11RL. Therefore, even if only one of the first power supply 71 and the second power supply 72 malfunctions, braking force can still be generated on one of the two right wheels and one of the two left wheels. As a result, the braking system 30 can suppress the deviation of the vehicle 10 when the vehicle is being braked.

[0038] (1-5) The first power supply 71 can supply power to two of the four braking units, but not to the remaining two. Similarly, the second power supply 72 can supply power to two of the four braking units, but not to the remaining two. Therefore, compared to a configuration where each of the two power supplies 71 and 72 can supply power to any of the four braking units, the braking system 30 can reduce the number of power supply lines.

[0039] (Second Embodiment) A second embodiment of the braking system will be described with reference to Figure 5. In the following description, the differences from the first embodiment will be mainly described, and the same reference numerals will be used for components that are the same as or equivalent to those in the first embodiment, and redundant explanations will be omitted.

[0040] As shown in Figure 5, in the braking system 30A of this embodiment, the first power supply 71 supplies power to the hydraulic braking device 40, that is, the two front wheel braking units 41FL, 41FR and the switching unit 43. On the other hand, the first power supply 71 cannot supply power to the two rear wheel braking units 60RL, 60RR. The second power supply 72 supplies power to the two rear wheel braking units 60RL, 60RR. On the other hand, the second power supply 72 cannot supply power to the hydraulic braking device 40.

[0041] <If an abnormality occurs in only the first power supply among the two power supplies> In this case, although the two front wheel braking units 41FL, 41FR and the switching unit 43 cannot operate, the two rear wheel braking units 60RL, 60RR can operate. Therefore, if a braking request occurs under these circumstances, the control device 80 will activate the two rear wheel braking units 60RL, 60RR to generate braking force in the two rear wheels 11RL, 11RR.

[0042] <If an abnormality occurs in only the second power supply of the two power supplies> In this case, although the two rear wheel braking units 60RL and 60RR cannot be operated, the two front wheel braking units 41FL and 41FR and the switching unit 43 can be operated. Therefore, if a braking request occurs under these circumstances, the control device 80 will activate the two front wheel braking units 41FL and 41FR to generate braking force in the two front wheels 11FL and 11FR.

[0043] Further, an abnormality may occur in only one of the two front-wheel braking units 41FL and 41FR. In this case, the control device 80 makes the switching unit 43 in a communicating state and then operates the other front-wheel braking unit in which no abnormality has occurred among the two front-wheel braking units 41FL and 41FR. Thereby, the control device 80 can generate braking force with the two front wheels 11FL and 11FR by operating only one of the two front-wheel braking units 41FL and 41FR.

[0044] In the braking system 30A of the present embodiment, effects equivalent to the effects (1-1), (1-4), and (1-5) of the first embodiment can be obtained. (Third Embodiment) A third embodiment of the braking system will be described according to FIG. 6. In the following description, mainly the parts different from the above-described plurality of embodiments will be described, and the same reference numerals will be given to the members and configurations that are the same as or equivalent to the above-described plurality of embodiments, and the redundant description will be omitted.

[0045] As shown in FIG. 6, in the braking system 30B of the present embodiment, the first power source 71 supplies power to the front-wheel braking unit 41FL for the left front wheel 11FL, the rear-wheel braking unit 60RL for the left rear wheel 11RL, and the switching unit 43. On the other hand, the first power source 71 cannot supply power to the front-wheel braking unit 41FR for the right front wheel 11FR and the rear-wheel braking unit 60RR for the right rear wheel 11RR. The second power source 72 supplies power to the front-wheel braking unit 41FR, the rear-wheel braking unit 60RR, and the switching unit 43. On the other hand, the second power source 72 cannot supply power to the front-wheel braking unit 41FL and the rear-wheel braking unit 60RL.

[0046] <When an abnormality occurs only in the first power source among the first power source and the second power source> In this case, although the front-wheel braking unit 41FL and the rear-wheel braking unit 60RL cannot operate, the front-wheel braking unit 41FR, the rear-wheel braking unit 60RR, and the switching unit 43 can operate. Therefore, when a braking request occurs under such a situation, the control device 80 makes the switching unit 43 in a communicating state and then operates the front-wheel braking unit 41FR. Further, the control device 80 operates the rear-wheel braking unit 60RR. Thereby, the control device 80 can generate braking force with three wheels, that is, the two front wheels 11FL and 11FR and the right rear wheel 11RR.

[0047] In addition, when an abnormality occurs only in the second power source 72 among the first power source 71 and the second power source 72, the operation is the same as when an abnormality occurs only in the first power source 71. Therefore, detailed description of such a case is omitted.

[0048] In the braking system 30B of the present embodiment, effects equivalent to the effects (1-1) to (1-5) of the first embodiment can be obtained. (Fourth Embodiment) A fourth embodiment of the braking system will be described with reference to FIG. 7. In the following description, mainly the parts different from the above-described plurality of embodiments will be described, and members and configurations identical or corresponding to the above-described plurality of embodiments will be denoted by the same reference numerals and redundant description will be omitted.

[0049] FIG. 7 shows a vehicle 10 including a braking system 30C of the present embodiment. The vehicle 10 includes two friction brakes 20RL and 20RR for the rear wheels. The friction brake 20RL corresponds to the left rear wheel 11RL. The friction brake 20RR corresponds to the right rear wheel 11RR. The configurations of the friction brakes 20RL and 20RR are substantially the same as those of the friction brakes 20FL and 20FR for the front wheels 11FL and 11FR. That is, the two friction brakes 20RL and 20RR can generate a braking force corresponding to the braking pressure of the wheel cylinder 21 at the corresponding rear wheels 11RL and 11RR.

[0050] <Configuration of Braking System> The braking system 30C includes, as a hydraulic braking device, a first hydraulic braking device 40L and a second hydraulic braking device 40R. The first hydraulic braking device 40L generates a braking force at the left wheels 11FL and 11RL by adjusting the braking pressure of the wheel cylinder 21 corresponding to the left wheels 11FL and 11RL. The second hydraulic braking device 40R generates a braking force at the right wheels 11FR and 11RR by adjusting the braking pressure of the wheel cylinder 21 corresponding to the right wheels 11FR and 11RR. That is, when the left wheels 11FL and 11RL are regarded as the "first wheels", the right wheels 11FR and 11RR correspond to the "second wheels". Conversely, when the right wheels 11FR and 11RR are regarded as the "first wheels", the left wheels 11FL and 11RL correspond to the "second wheels".

[0051] The first hydraulic braking device 40L includes a front wheel braking unit 41FL, a rear wheel braking unit 160RL, and a first switching unit 43L. The second hydraulic braking device 40R includes a front wheel braking unit 41FR, a rear wheel braking unit 160RR, and a second switching unit 43R. The rear wheel braking units 160RL and 160RR have, for example, the same electric cylinder 50 shown in Figure 2 as the front wheel braking units 41FL and 41FR.

[0052] The rear wheel braking unit 160RL is in communication with the wheel cylinder 21 of the friction brake 20RL for the left rear wheel 11RL via the supply passage 42RL. The rear wheel braking unit 160RR is in communication with the wheel cylinder 21 of the friction brake 20RR for the right rear wheel 11RR via the supply passage 42RR.

[0053] The first switching unit 43L is configured to switch between a communication state, which connects the wheel cylinder 21 for the left front wheel 11FL and the wheel cylinder 21 for the left rear wheel 11RL, and a disconnection state, which disconnects the two wheel cylinders 21. The first switching unit 43L includes a first communication passage 44L that connects the supply passage 42FL and the supply passage 42RL, and a shut-off valve 45L installed in the first communication passage 44L. An example of the shut-off valve 45L is a normally open solenoid valve.

[0054] The second switching unit 43R is configured to switch between a communication state, which connects the wheel cylinder 21 for the right front wheel 11FR and the wheel cylinder 21 for the right rear wheel 11RR, and a disconnection state, which disconnects the two wheel cylinders 21. The second switching unit 43R includes a second communication passage 44R connecting the supply passage 42FR and the supply passage 42RR, and a shut-off valve 45R installed in the second communication passage 44R. An example of the shut-off valve 45R is a normally open solenoid valve.

[0055] The first power supply 71 supplies power to the two front wheel braking units 41FL and 41FR, and to the first switching unit 43L and the second switching unit 43R. The second power supply 72 supplies power to the two rear wheel braking units 160RL and 160RR, and to the first switching unit 43L and the second switching unit 43R. In other words, the two front wheel braking units 41FL and 41FR correspond to the "first braking unit," and the two rear wheel braking units 160RL and 160RR correspond to the "second braking unit."

[0056] <If an abnormality occurs in only the first power supply of the two power supplies> In this case, although the two front wheel braking units 41FL and 41FR cannot be operated, the two rear wheel braking units 160RL and 160RR, and the first switching unit 43L and the second switching unit 43R can be operated. Therefore, the control device 80 connects the first switching unit 43L and the second switching unit 43R and then operates the two rear wheel braking units 160RL and 160RR. As a result, the control device 80 can generate braking force on all four wheels 11FL, 11FR, 11RL, and 11RR.

[0057] Furthermore, in the case where only the second power supply 72 of the two power supplies 72 (the first power supply 71 and the second power supply 72) malfunctions, the situation is the same as when only the first power supply 71 malfunctions, except that the braking units supplied with power are the two front wheel braking units 41FL and 41FR.

[0058] (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.

[0059] In the fourth embodiment described above, the two braking units for the right wheel 11FR, 11RR or the left wheel 11FL, 11RL may be electric braking devices that generate braking force without using brake fluid.

[0060] In the third embodiment described above, if the second power supply 72 can supply power to the shut-off valve 45, the first power supply 71 does not need to supply power to the switching unit 43. In this case, if an abnormality occurs in the second power supply 72, power will no longer be supplied to the shut-off valve 45, and the switching unit 43 will open. In other words, the switching unit 43 will be in a communication state. Therefore, braking force can be generated on the two front wheels 11FL and 11FR by the operation of the front wheel braking unit 41FL.

[0061] - The switching units 43, 43L, and 43R may have configurations different from those described in the above multiple embodiments, as long as they are capable of switching between a connected state and a disconnected state. - In the first embodiment, the braking system may be configured to include a hydraulic braking device that can adjust the braking force of the two rear wheels 11RL and 11RR. In this case, the two rear wheels 11RL and 11RR correspond to the "first wheels," and the two front wheels 11FL and 11FR correspond to the "second wheels."

[0062] - The brake fluid supply source to the wheel cylinder 21 does not have to be the electric cylinder 50 shown in Figure 2, as long as the brake fluid can be supplied by driving an electric motor. For example, the supply source may be an electric pump or a configuration equipped with an accumulator.

[0063] The control device 80 may be configured as a circuit 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.

[0064] (Other technical ideas) The technical ideas that can be understood from the above multiple embodiments and modifications are described below. [Note 1] It is preferable that the two first braking units each have an electric motor supplied with power from the first power source and generate a braking force in the corresponding wheel corresponding to the drive of the electric motor, and that the two second braking units each have an electric motor supplied with power from the second power source and generate a braking force in the corresponding wheel corresponding to the drive of the electric motor.

[0065] [Note 2] The switching unit is preferably operated by power supplied from at least one of the first power supply and the second power supply.

[0066] [Note 3] The switching unit has a normally open solenoid valve, and it is preferable that the switching unit is in the shut-off state when the solenoid valve is closed, and in the communication state when the solenoid valve is open.

[0067] [Note 4] The vehicle is equipped with a control device that controls the four braking units, and the control device adjusts the braking force of the vehicle by setting the switching unit to the communication state when an abnormality occurs in only one of the first power supply and the second power supply, and activating the braking unit among the four braking units that operates with power supplied from a power supply where no abnormality has occurred.

[0068] 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 system provided on a vehicle having two first wheels and two second wheels, wherein the two first wheels are configured to generate a braking force corresponding to the hydraulic pressure of the corresponding wheel cylinders, comprising: a hydraulic braking device provided corresponding to each of the two wheel cylinders and having two braking units that electrically adjust the hydraulic pressure of the corresponding wheel cylinders, and a switching unit that can switch between a connected state in which the two wheel cylinders are in communication and a disconnected state in which the two wheel cylinders are not in communication; two braking units provided corresponding to each of the two second wheels and electrically adjust the braking force generated by the corresponding second wheel; a first power supply that supplies power to two first braking units which are specific braking units among the four braking units; and a second power supply that supplies power to two second braking units which are braking units other than the first braking units among the four braking units.

2. The braking system according to claim 1, wherein the two braking units of the hydraulic braking device include one of the two first braking units and one of the two second braking units.

3. The braking system according to claim 1 or 2, wherein the two first wheels include a right wheel (one of the right front wheel and the right rear wheel) and a left wheel (one of the left front wheel and the left rear wheel), and the hydraulic braking device generates braking force on the one right wheel and the one left wheel by activating one of the two braking units provided in the hydraulic braking device when the switching unit is in the communication state.

Images