Electric braking device

Abstract

To facilitate transfer of brake fluid in a liquid passage into a hydraulic chamber when pressure in the liquid passage becomes negative pressure.SOLUTION: An electric braking device (1A) includes: a reservoir (11) that reserves brake fluid; and a liquid passage (12) that connects the reservoir (11) and a hydraulic chamber (H). The liquid passage (12) includes a deformation part (21) in which at least a part of the liquid passage (12) is deformed to send the brake fluid to the hydraulic chamber (H) when hydraulic pressure becomes negative pressure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an electric braking system. [Background technology]

[0002] Patent Document 1 discloses a technique for supporting suction control by an electric cylinder by storing brake fluid under a storage chamber pressure higher than atmospheric pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] German Patent Application Publication No. 102015226568 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology disclosed in Patent Document 1, a piston in a storage chamber is biased by a spring to store brake fluid at a pressure higher than atmospheric pressure. When brake fluid is present in the storage chamber, that is, when the storage chamber pressure is equal to or higher than atmospheric pressure, suction control can be supported. However, when the brake fluid in the storage chamber runs out, brake fluid must be sucked into the storage chamber from a main reservoir located far away, which increases the impact of pressure loss and makes it impossible to support suction control. An object of one aspect of the present disclosure is to provide an electric braking device that can easily send brake fluid in a fluid passage into a hydraulic chamber when the pressure in the fluid passage becomes negative. [Means for solving the problem]

[0005] In order to solve the above problems, one embodiment of the electric braking device of the present disclosure is an electric braking device that can apply braking force to the wheels of a vehicle by advancing or retracting a piston in a cylinder in response to the drive of an electric motor, and by using a pressure supply device that draws and discharges brake fluid in a hydraulic chamber partitioned by the cylinder and the piston into a wheel cylinder, the electric braking device comprising: a reservoir that stores the brake fluid; and a hydraulic passage that connects the reservoir to the hydraulic chamber, the hydraulic passage including a deformation portion that deforms at least a part of the hydraulic passage so as to send the brake fluid in the hydraulic passage into the hydraulic chamber when the pressure in the hydraulic passage becomes negative. [Effects of the Invention]

[0006] According to one aspect of the present disclosure, when the pressure in the fluid passage becomes negative, it is possible to easily send brake fluid in the fluid passage into the hydraulic chamber. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a hydraulic circuit diagram for explaining an electric braking device according to a first embodiment of the present disclosure. [Figure 2] FIG. 6 is a hydraulic circuit diagram for explaining an electric braking device according to a second embodiment of the present disclosure. [Figure 3] FIG. 10 is a hydraulic circuit diagram for explaining an electric braking device according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Embodiment 1] Fig. 1 is a hydraulic circuit diagram for explaining an electric braking device according to a first embodiment of the present disclosure. The electric braking device 1A shown in Fig. 1 includes a control unit 10, a reservoir 11, a fluid passage 12, a check valve 20, a pressure supply device A, solenoid valves VL1 and VL2, and a wheel cylinder WC. The electric braking device 1A is mounted on a vehicle having a plurality of wheels W.

[0009] The pressure supply device A is an electric cylinder and includes a cylinder C, a piston P, an electric motor M, and a rotation angle sensor R. When the piston P moves linearly within the cylinder C in response to the drive of the electric motor M, the volume of the hydraulic chamber H defined by the cylinder C and the piston P changes. When the piston P moves forward within the cylinder C, the brake fluid within the hydraulic chamber H is discharged to the wheel cylinder WC. The rotation angle sensor R detects the rotation angle of the rotor of the electric motor M. The position of the piston P of the pressure supply device A can be obtained based on the detection result of the rotation angle sensor R.

[0010] The reservoir 11 stores brake fluid. The fluid path 12 connects the reservoir 11 and the hydraulic chamber H of the pressure supply device A. The fluid path 12 has a first fluid path 21 and a second fluid path 22. A check valve 20 is disposed between the first fluid path 21 and the second fluid path 22. The check valve 20 opens when the fluid pressure in the second fluid path 22 becomes lower than the fluid pressure in the first fluid path 21, i.e., when the pressure on the second fluid path 22 side of the check valve 20 becomes negative pressure, thereby allowing the flow of brake fluid from the reservoir 11 to the pressure supply device A. On the other hand, the check valve 20 restricts the flow of brake fluid from the pressure supply device A to the reservoir 11.

[0011] The first liquid path 21 is an example of a deformable portion, and is made of a material having a lower elastic modulus than the second liquid path 22. For example, the first liquid path 21 is made of a rubber hose. The first liquid path 21 may be longer than the second liquid path 22.

[0012] The solenoid valve VL1 opens and closes the fluid path between the hydraulic chamber H of the pressure supply device A and the wheel cylinder WC. When the solenoid valve VL1 is open, the hydraulic chamber H of the pressure supply device A and the wheel cylinder WC are in communication with each other. When the solenoid valve VL1 is closed, the hydraulic chamber H of the pressure supply device A and the wheel cylinder WC are cut off from each other.

[0013] The solenoid valve VL2 opens and closes the fluid path between the reservoir 11 and the wheel cylinder WC. When the solenoid valve VL2 is open, the reservoir 11 and the wheel cylinder WC are in communication with each other. When the solenoid valve VL2 is closed, the reservoir 11 and the wheel cylinder WC are not in communication with each other.

[0014] The control unit 10 is, for example, an ECU including a microcomputer. The control unit 10 is used, for example, for antilock brake control that prevents the wheels W from locking during braking. The antilock brake control includes, for example, a pressure reduction mode in which the hydraulic pressure in the wheel cylinder WC is reduced by closing the solenoid valve VL1 and opening the solenoid valve VL2, a pressure retention mode in which the hydraulic pressure in the wheel cylinder WC is maintained by closing the solenoid valves VL1 and VL2, and a pressure increase mode in which the hydraulic pressure in the wheel cylinder WC is increased by opening the solenoid valve VL1, closing the solenoid valve VL2, and then driving the pressure supply device A.

[0015] When brake fluid is returned from the wheel cylinder WC to the reservoir 11 in the pressure reduction mode, the total amount of brake fluid in the hydraulic chamber H of the pressure supply device A and the wheel cylinder WC decreases. This may cause bottoming, in which the piston P of the pressure supply device A collides with the bottom surface B of the cylinder C, so the control unit 10 performs refill control (suction control).

[0016] In the refill control, the control unit 10 closes the solenoid valve VL1. Then, the control unit 10 moves the piston P of the pressure supply device A backward to suck the brake fluid from the reservoir 11 into the hydraulic chamber H of the pressure supply device A. At this time, the hydraulic path 12 may become negative pressure.

[0017] When the hydraulic passage 12 becomes negative pressure, the first hydraulic passage 21 is elastically deformed and recessed. The recession of the first hydraulic passage 21 makes it easier to send brake fluid from the reservoir 11 to the hydraulic chamber H of the pressure supply device A. Furthermore, the second hydraulic passage 22 is formed with a higher elastic modulus than the first hydraulic passage 21, so the second hydraulic passage 22, which has a larger pressure loss than the first hydraulic passage 21, is less likely to deform, and therefore is less likely to become blocked. Furthermore, the second hydraulic passage 22 on the hydraulic chamber H side of the pressure supply device A is formed with a higher elastic modulus than the check valve 20, so that when brake fluid is discharged from the hydraulic chamber H of the pressure supply device A, the brake fluid sent to the wheel cylinder WC is prevented from being consumed due to expansion of the second hydraulic passage 22.

[0018] [Embodiment 2] A second embodiment of the present disclosure will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the first embodiment, and the description thereof will not be repeated.

[0019] Fig. 2 is a hydraulic circuit diagram for explaining an electric braking device according to a second embodiment of the present disclosure. In the electric braking device 1B shown in Fig. 2, the hydraulic path 12 does not have a check valve 20 or a first hydraulic path 21. In the electric braking device 1B, the hydraulic path 12 includes a seal member 31 provided at a connection portion 30 between the hydraulic path 12 and a housing of the pressure supply device A in which the hydraulic pressure chamber H is provided.

[0020] The seal member 31 is an example of a deformable portion, and for example, a part of the seal member 31 is formed of a diaphragm (elastic thin film). The seal member 31 exhibits a sealing function when both ends of the seal member 31 come into close contact with the pressure supply device A and the liquid path 12, respectively, at the connection portion 30. The central portion between both ends of the seal member 31 is formed of an elastic thin film, i.e., a diaphragm.

[0021] When the hydraulic passage 12 is under negative pressure, the center portion of the sealing member 31 is elastically deformed toward the hydraulic pressure chamber H. This makes it easier to send brake fluid from the reservoir 11 to the hydraulic pressure chamber H of the pressure supply device A.

[0022] [Embodiment 3] A third embodiment of the present disclosure will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the first and second embodiments, and the description thereof will not be repeated.

[0023] 3 is a hydraulic circuit diagram for explaining an electric braking device according to a third embodiment of the present disclosure. In the electric braking device 1C shown in FIG. 3, a fluid reservoir 40 having a predetermined volume is provided in a part of the fluid path 12.

[0024] The fluid reservoir 40 has a space inside that can store brake fluid, and an air reservoir 41 is disposed within that space. The air reservoir 41 is, for example, a sealed container formed from a thin film of an elastic material such as rubber, and air is sealed in it. The air reservoir 41 expands when the fluid pressure in the fluid path 12 decreases, and contracts when the fluid pressure in the fluid path 12 increases.

[0025] The fluid reservoir 40 has a structure that prevents the fluid passage 12 from being blocked when the air reservoir 41 expands. The internal space of the fluid reservoir 40 extends in direction R1 from the connection portion with the piping of the fluid passage 12. The fluid reservoir 40 is positioned so that direction R1 is closer to the vertically upward direction than the vertically downward direction. The air reservoir 41 has a lower density than the brake fluid, and is positioned in direction R1 due to buoyancy.

[0026] When the electric braking device 1C is mounted on a vehicle, the liquid reservoir 40 is preferably installed in a position in which the direction R1 faces vertically upward. The liquid reservoir 40 is preferably connected to the piping of the liquid passage 12 on the ground side, and the air reservoir 41 is preferably located vertically upward inside the liquid reservoir 40.

[0027] The air reservoir 41 is an example of a deformable portion. When the hydraulic passage 12 is under negative pressure, the air reservoir 41 expands, making it easier to send brake fluid from the reservoir 11 to the hydraulic chamber H of the pressure supply device A.

[0028] [Modification] In the third embodiment, air reservoir 41 is an airtight container made of an elastic material such as rubber and filled with air. However, air reservoir 41 may be formed by directly filling air into reservoir 40, as long as reservoir 40 has a structure that prevents air from leaking into the piping of liquid path 12.

[0029] 〔summary〕 An electric braking device according to one aspect of the present disclosure is an electric braking device that can apply braking force to the wheels of a vehicle by advancing or retracting a piston in a cylinder in response to the drive of an electric motor, and by using a pressure supply device that draws and discharges brake fluid in a hydraulic chamber partitioned by the cylinder and the piston into a wheel cylinder, and the electric braking device comprises a reservoir that stores the brake fluid, and a hydraulic passage that connects the reservoir to the hydraulic chamber, and the hydraulic passage includes a deformation portion that deforms at least a part of the hydraulic passage so as to send the brake fluid in the hydraulic passage into the hydraulic chamber when the pressure in the hydraulic passage becomes negative. When the pressure in the hydraulic passage becomes negative, at least a portion of the hydraulic passage is deformed, which makes it easier to send brake fluid from the hydraulic passage to the hydraulic chamber. Therefore, even if the pressure loss between the reservoir and the hydraulic chamber is high, it is easier to send brake fluid from the hydraulic passage to the hydraulic chamber.

[0030] In one aspect of the electric braking device of the present disclosure, the fluid path is provided with a check valve that allows the brake fluid to flow from the reservoir to the hydraulic chamber, and the deformation portion is configured by making the elastic modulus of the fluid path on the reservoir side of the check valve lower than the elastic modulus of the fluid path on the hydraulic chamber side of the check valve. The greater the distance between the reservoir and the hydraulic chamber, the greater the pressure difference between them, resulting in greater stress. The second hydraulic line on the hydraulic chamber side of the check valve has a higher elastic modulus than the first hydraulic line on the reservoir side of the check valve, preventing blockage of the hydraulic line. Meanwhile, by making the elastic modulus of the first hydraulic line on the reservoir side of the check valve lower than that of the second hydraulic line on the hydraulic chamber side of the check valve, it becomes easier to send brake fluid from the first hydraulic line on the reservoir side of the check valve to the hydraulic chamber.

[0031] In one aspect of the electric braking device of the present disclosure, the hydraulic path further has a sealing member provided at the connection portion between the reservoir and the housing of the pressure supply device in which the hydraulic chamber is provided, and the deformation portion is constituted by at least a portion of the sealing member being formed by a diaphragm. According to the above configuration, by making at least a portion of the sealing member provided at the connection portion between the reservoir and the housing in which the hydraulic chamber is provided a diaphragm, it is possible to make it easier to send brake fluid in the hydraulic path to the hydraulic chamber with a simple configuration.

[0032] In one aspect of the electric braking device of the present disclosure, the fluid path further has a fluid reservoir having a predetermined volume, and the deformation portion is constituted by an air reservoir provided inside the fluid reservoir. According to the above configuration, by providing an air reservoir inside the fluid reservoir, when the pressure in the fluid path becomes negative, the air in the air reservoir expands, making it easier to send the brake fluid in the fluid path to the hydraulic chamber.

[0033] In one embodiment of the electric braking device of the present disclosure, when mounted on a vehicle, the liquid reservoir extends vertically upward from the portion that connects to the piping of the liquid path, and the air reservoir is located inside the liquid reservoir, vertically upward from the portion that connects to the piping of the liquid path. According to the above configuration, it is possible to prevent the liquid path from being blocked by air pockets. [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0034] 1A, 1B, 1C Electric braking device 11 Reservoir 12 Liquid path 20. Check valve 21 First liquid path (deformed portion) 22 2nd liquid path 30 Connection part 31 Sealing member (deformed part) 40 Liquid pool 41 Air pocket (deformed part) A Pressure supply device C cylinder H Hydraulic chamber M Electric Motor P piston W wheels WC Wheel Cylinder

Claims

1. An electric braking device capable of applying braking force to vehicle wheels by a pressure supply device that draws and discharges brake fluid from a hydraulic chamber defined by the cylinder and the piston to a wheel cylinder by advancing or retracting a piston in a cylinder in response to driving of an electric motor, a reservoir that stores the brake fluid; a fluid passage connecting the reservoir and the hydraulic chamber, An electric braking device in which the hydraulic passage includes a deformation portion in which at least a portion of the hydraulic passage is deformed so as to send brake fluid in the hydraulic passage into the hydraulic pressure chamber when the pressure in the hydraulic passage becomes negative.

2. a check valve that allows the brake fluid to flow from the reservoir to the hydraulic chamber is provided in the hydraulic path; 2. The electric braking device according to claim 1, wherein the deforming portion is configured by making the elastic modulus of a fluid passage on the reservoir side of the check valve lower than the elastic modulus of a fluid passage on the hydraulic pressure chamber side of the check valve.

3. the fluid path further includes a seal member provided at a connection portion between the reservoir and a housing of the pressure supply device in which the fluid pressure chamber is provided, 2. The electric braking device according to claim 1, wherein the deformation portion is configured by at least a portion of the seal member being formed by a diaphragm.

4. the liquid path further includes a liquid reservoir having a predetermined volume; 2. The electric braking device according to claim 1, wherein the deformation portion is formed by an air reservoir provided inside the liquid reservoir.

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