Braking device

Abstract

Reduce the axial size of the cylinder. [Solution] The braking device (1) comprises a housing (10), a cylinder (20) formed separately from the housing (10) and at least a portion of which is inserted into the housing (10), and a sealing member (70) provided between the cylinder (20) and the housing (10) and sealing the space between the cylinder (20) and the housing (10) in the axial direction of the cylinder (20).

Description

Technical Field

[0001] The present disclosure relates to a braking device.

Background Art

[0002] In the braking system disclosed in Patent Document 1, in a configuration where an electric cylinder and a housing are separate bodies, the brake fluid is sealed at the connection point between the hydraulic chamber of the electric cylinder and the brake fluid passage of the housing so as not to leak.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the braking system disclosed in Patent Document 1, since it is sealed in the radial direction of the cylinder by a seal member provided between the cylinder and the housing, the cylinder becomes larger in the axial direction of the cylinder by the amount of the seal member. One aspect of the present disclosure aims to solve the above problems.

Means for Solving the Problems

[0005] In order to solve the above problems, a braking device according to one aspect of the present disclosure includes a housing, a cylinder formed separately from the housing and at least partially inserted into the housing, and a seal member provided between the cylinder and the housing for sealing between the cylinder and the housing in the axial direction of the cylinder.

Effects of the Invention

[0006] According to one aspect of the present disclosure, the physical size of the cylinder in the axial direction can be reduced. [Brief explanation of the drawing]

[0007] [Figure 1] This is a cross-sectional view of the braking device according to Embodiment 1 of this disclosure. [Figure 2] This is a schematic diagram showing an example of the structure of a cylinder seal. [Figure 3] This is a cross-sectional view of the braking device according to Embodiment 2 of this disclosure. [Modes for carrying out the invention]

[0008] [Embodiment 1] Figure 1 is a cross-sectional view of a braking device according to Embodiment 1 of this disclosure. The braking device 1 according to Embodiment 1 shown in Figure 1 is connected to a wheel cylinder WC and a reservoir tank RT. The reservoir tank RT is a tank for storing brake fluid. The braking device 1 controls the hydraulic pressure of the wheel cylinder WC. The wheel cylinder WC generates braking force on the vehicle's wheel W by pressing a friction material 91 against a brake disc 92 that rotates together with the vehicle's wheel W.

[0009] The braking device 1 comprises a housing 10, a cylinder 20, a piston 30, a linear motion conversion mechanism 40, piston seals 50 and 51, and a cylinder seal 60. The housing 10 has an insertion hole 10A, a first brake fluid passage 11, and a second brake fluid passage 12. The cylinder 20 is formed separately from the housing 10. At least a portion of the cylinder 20 is inserted into the insertion hole 10A of the housing 10. When the cylinder 20 is inserted into the insertion hole 10A of the housing 10, the outer circumference 20B of the cylinder 20 faces the inner circumference of the insertion hole 10A of the housing 10.

[0010] Inside the cylinder 20, a hydraulic chamber 23, into which brake fluid can be filled, is partitioned by the piston 30. The cylinder 20 has a first connecting fluid passage 21 and a second connecting fluid passage 22.

[0011] The first brake fluid passage 11 of the housing 10 and the first connecting fluid passage 21 of the cylinder 20 constitute a part of the fluid passage from the hydraulic chamber 23 to the reservoir RT. The first connecting fluid passage 21 of the cylinder 20 connects the hydraulic chamber 23 to the first brake fluid passage 11 of the housing 10.

[0012] The second brake fluid passage 12 of the housing 10 and the second connecting fluid passage 22 of the cylinder 20 constitute a part of the fluid passage from the hydraulic chamber 23 to the wheel cylinder WC. The second connecting fluid passage 22 of the cylinder 20 connects the hydraulic chamber 23 to the second brake fluid passage 12.

[0013] The linear motion conversion mechanism 40 is a screw mechanism having a screw shaft 41 and a nut 42. The screw shaft 41 extends in a direction parallel to the central axis 20A of the cylinder 20 (hereinafter referred to as the axial direction of the cylinder 20). The nut 42 converts the rotation of the screw shaft 41 into linear motion. The piston 30 is fixed to the nut 42 and moves linearly together with the nut 42. As the piston 30 moves linearly, the volume of the hydraulic chamber 23 of the cylinder 20 changes. Hereinafter, the direction of movement of the piston 30 that reduces the volume of the hydraulic chamber 23 of the cylinder 20 will be described as the forward direction F, and the direction of movement of the piston 30 that increases the volume of the hydraulic chamber 23 of the cylinder 20 will be described as the backward direction R. The forward direction F and the backward direction R are parallel to the axial direction of the cylinder 20.

[0014] When the piston 30 moves linearly in the forward direction F beyond a predetermined distance, the piston 30 exceeds the seal portion 51, blocking the opening of the first connecting fluid passage 21 on the hydraulic chamber 23 side, and the first connecting fluid passage 21 is closed. When the piston 30 moves linearly in the backward direction R, and the state of blocking the opening of the first connecting fluid passage 21 on the hydraulic chamber 23 side is released, brake fluid flows from the reservoir tank RT into the hydraulic chamber 23.

[0015] The piston seal portion 50 is a sealing member provided between the cylinder 20 and the piston 30, and prevents brake fluid from leaking from the hydraulic chamber 23.

[0016] The cylinder seal portion 60 is a seal structure provided between the housing 10 and the cylinder 20. A seal member 70 is housed in the cylinder seal portion 60. The seal member 70 of the cylinder seal portion 60 is, for example, an annular O-ring, and its central axis is the same as the central axis 20A of the cylinder 20.

[0017] The cylinder seal portion 60 is provided at the facing portion 24 where the cylinder 20 faces the housing 10 in the axial direction of the cylinder 20. The cylinder seal portion 60 seals between the housing 10 and the cylinder 20 in the axial direction of the cylinder 20. Sealing between the housing 10 and the cylinder 20 in the axial direction of the cylinder 20 means that the seal member 70 closely contacts the housing 10 and the cylinder 20 in the axial direction of the cylinder 20 to prevent the outflow of brake fluid and the entry of foreign matter.

[0018] A plurality of cylinder seal portions 60 are provided between the housing 10 and the cylinder 20, partitioning a first region 25 that connects the first brake fluid passage 11 and the first connection fluid passage 21, and a second region 26 that connects the second brake fluid passage 12 and the second connection fluid passage 22. In FIG. 1, three cylinder seal portions 60 are provided between the housing 10 and the cylinder 20. Of the three cylinder seal portions 60, the cylinder seal portion 60A located on the most rearward direction R side and the cylinder seal portion 60B located in the middle partition the first region 25. Of the three cylinder seal portions 60, the cylinder seal portion 60C located on the most forward direction R side and the cylinder seal portion 60B located in the middle partition the second region 26.

[0019] The first connection fluid passage 21 is connected to the first brake fluid passage 11 via the first region 25. The second connection fluid passage 22 is connected to the second brake fluid passage 12 via the second region 26. By providing the cylinder seal portion 60 between the housing 10 and the cylinder 20, even if the housing 10 and the cylinder 20 are formed separately, brake fluid does not leak between the housing 10 and the cylinder 20, and foreign matter does not enter the fluid passage of the brake fluid.

[0020] FIG. 2 is a schematic diagram showing an example of the structure of the cylinder seal portion. In the cylinder seal portion 60, the inner periphery of the insertion hole 10A of the housing 10 and the outer periphery 20B of the cylinder 20 extend in a direction intersecting the axial direction of the cylinder 20, for example, in the radial direction of the cylinder 20. In the cylinder seal portion 60, the inner periphery of the insertion hole 10A of the housing 10 and the outer periphery 20B of the cylinder 20 face each other in the axial direction of the cylinder 20.

[0021] In FIG. 2, in the cylinder seal portion 60, the outer periphery 20B of the cylinder 20 has a contact portion 81, a seal accommodation groove 82, and a contact portion 83. The inner periphery of the insertion hole 10A of the housing 10 has a contact portion 71, a seal accommodation groove 72, and a contact portion 73.

[0022] The contact portion 81 of the cylinder 20 faces the contact portion 71 of the housing 10 and contacts the contact portion 71 of the housing 10. The contact portion 83 of the cylinder 20 faces the contact portion 73 of the housing 10 and contacts the contact portion 73 of the housing 10.

[0023] The seal accommodation groove 82 of the cylinder 20 is formed by the outer periphery 20B of the cylinder 20 being recessed in a retreat direction R parallel to the axial direction of the cylinder 20. The seal accommodation groove 82 of the cylinder 20 is an example of a seal portion. The seal accommodation groove 72 of the housing 10 is formed by the inner periphery of the insertion hole 10A of the housing 10 being recessed in a forward direction F parallel to the axial direction of the cylinder 20. The bottom surface of the seal accommodation groove 8 of the cylinder 20 faces the bottom surface of the seal accommodation groove 72 of the housing 10. A seal member 70 is sandwiched between the bottom surface of the seal accommodation groove 72 of the housing 10 and the bottom surface of the seal accommodation groove 82 of the cylinder 20. The seal member 70 is accommodated in an elastically deformed state between the seal accommodation groove 72 and the seal accommodation groove 82. The seal member 70 is in close contact with the bottom surfaces of the seal accommodation groove 72 and the seal accommodation groove 82, and seals between the housing 10 and the cylinder 20 in the axial direction of the cylinder 20.

[0024] As shown in Figure 1, the multiple cylinder seal portions 60 seal the space between the cylinder 20 and the housing 10 in the axial direction of the cylinder 20, so the multiple cylinder seal portions 60 are compressed in the axial direction of the cylinder 20. Therefore, the axial size of the cylinder 20 can be reduced compared to when the space between the housing 10 and the cylinder 20 is sealed in the radial direction of the cylinder 20. In addition, the multiple cylinder seal portions 60 are arranged at different radial distances from the central axis 20A of the cylinder 20. By arranging them in this way, in a plan view, the seal housing grooves 82 of the cylinder seal portions 60 can be overlapped with the seal housing grooves 72 of the other cylinder seal portions 60. This also allows the axial size of the cylinder 20 to be reduced compared to when the space between the housing 10 and the cylinder 20 is sealed in the radial direction of the cylinder 20. The axial size of the cylinder 20 refers to the axial length of the cylinder 20 as part of the outer dimensions of the cylinder 20.

[0025] The first connecting fluid passage 21 opens to the contact portion 81 of the cylinder seal portion 60A located furthest to the forward direction F among the cylinder seal portions 60 that define the first region 25. The first brake fluid passage 11 opens to the contact portion 71 of the cylinder seal portion 60A located furthest to the forward direction F among the cylinder seal portions 60 that define the first region 25. In this way, even when the seal housing groove 82 of the cylinder seal portion 60 overlaps with the seal housing groove 72 of other cylinder seal portions 60 in a plan view, the shapes of the first connecting fluid passage 21 and the first brake fluid passage 11 do not become complicated, and the housing 10 and cylinder 20 can be easily manufactured.

[0026] For example, the first connecting fluid passage 21 may be formed by cutting from the inside of the cylinder 20 in the radial direction of the cylinder 20 and connecting it to a hole formed by cutting in the backward direction R from the contact portion 81 of the cylinder seal portion 60. When cutting from the inside of the cylinder 20 in the radial direction of the cylinder 20, the hole may be formed in the shape of a disc. The second connecting fluid passage 22 may also be formed by a similar manufacturing method.

[0027] The first brake fluid passage 11 may be formed by machining the housing 10 in the axial direction of the cylinder 20. The second brake fluid passage 12 may also be formed by a similar manufacturing method.

[0028] In the cylinder seal portion 60, the seal housing grooves 72 and 82 have contact portions 71 and 81 and contact portions 73 and 83, which are positioned differently in the radial direction of the cylinder 20. By providing contact portions 71 and 81 and contact portions 73 and 83 in the cylinder seal portion 60, the axial distance of the cylinder 20 that crushes the seal member 70 can be easily determined at the design stage of the braking device 1.

[0029] [Embodiment 2] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0030] Figure 3 is a cross-sectional view of a braking device according to Embodiment 2 of the present disclosure. In the braking device 1 according to Embodiment 2 shown in Figure 3, a second region 26 interposed between the second brake fluid passage 12 and the second connecting fluid passage 22 is partitioned by a cylinder seal portion 61, and a first region 25 is partitioned by a cylinder seal portion 60 and a cylinder seal portion 61.

[0031] The cylinder seal portion 61 seals the space between the housing 10 and the cylinder 20 in the radial direction of the cylinder 20. That is, it seals the space between the housing 10 and the cylinder 20 in a direction intersecting the direction in which the cylinder 20 is inserted into the insertion hole 10A of the housing 10.

[0032] In the second region 26 interposed between the second brake fluid passage 12 and the second connecting fluid passage 22, an internal pressure corresponding to the fluid pressure of the wheel cylinder WC is applied in a direction that widens the gap between the housing 10 and the cylinder 20. In Embodiment 2, since the internal pressure of the second region 26 is applied radially to the cylinder 20, the cylinder 20 is less likely to shift in the direction in which it is inserted into the insertion hole 10A of the housing 10 (axial direction of the cylinder 20). In contrast, in the first region 25 interposed between the first brake fluid passage 11 and the first connecting fluid passage 21, the fluid pressure of the reservoir tank RT, which is atmospheric pressure, is maintained. Therefore, in Embodiment 2, the internal pressure of the first region 25 does not increase, and displacement of the cylinder 20 in the direction in which it is inserted into the insertion hole 10A of the housing 10 (axial direction of the cylinder 20) can be suppressed. Furthermore, if the internal pressure of the first region 25 is set to be higher than atmospheric pressure, it is preferable to design the structure so that the internal pressure of the first region 25 is less than the holding force that holds the cylinder 20 to the housing 10. This prevents the cylinder 20 from shifting axially from the housing 10 even if the internal pressure of the first region 25 is applied in the direction in which the cylinder 20 is inserted into the insertion hole 10A of the housing 10 (axial direction of the cylinder 20), thereby maintaining the sealing performance between the housing and the cylinder. Methods for holding the cylinder 20 to the housing 10 include bolting and crimping.

[0033] [Variation] In embodiments 1 and 2 described above, the braking device 1 partitions a hydraulic chamber 23 inside the cylinder 20 with a piston 30, changes the volume of the hydraulic chamber 23 by moving the piston 30 in a linear motion, controls the hydraulic pressure of the wheel cylinder WC and generates a braking force on the wheel W. The cylinder seal portion 60 can be applied to braking devices other than those that generate a braking force on the wheel W by controlling the hydraulic pressure of the wheel cylinder WC. For example, the cylinder seal portion 60 can also be applied to a braking device in which the piston 30 presses the friction material 91 against the brake disc 92 without the use of brake fluid. In a braking device in which the piston 30 presses the friction material 91 against the brake disc 92, by providing at least one cylinder seal portion 60 between the housing and the cylinder, it is possible to prevent foreign matter from entering between the housing and the cylinder.

[0034] In embodiments 1 and 2 described above, the cylinder seal portion 60 has contact portions 71 and 81, seal housing grooves 72 and 82, and contact portions 73 and 83 as shown in Figure 2. However, the shape of the cylinder seal portion 60 is not limited to that shown in Figure 2. For example, in the cylinder seal portion 60, either the contact portion 81 or the contact portion 83 of the cylinder 20 may be configured not to contact the housing 10. Also, the cylinder seal portion 60 may have seal housing grooves 72 or 82 formed in at least one of the housing 10 or the cylinder 20, as long as it can seal the space between the housing 10 and the cylinder 20 in the axial direction of the cylinder 20. If a seal housing groove 72 is formed in the housing 10, the seal housing groove 82 of the cylinder 20 does not need to be recessed in the axial direction of the cylinder 20, but may protrude in the axial direction of the cylinder 20. If a seal housing groove 82 is formed in the cylinder 20, the seal housing groove 72 of the housing 10 does not need to be recessed in the axial direction of the cylinder 20, but may protrude in the axial direction of the cylinder 20.

[0035] In the above embodiment 1, the first connecting fluid passage 21 is assumed to open to the contact portion 81 of the cylinder seal portion 60B, which is one of the cylinder seal portions 60A and 60B that demarcate the first region 25, but it may also be assumed to open to the contact portion 83 of the cylinder seal portion 60A.

[0036] In the above embodiment 1, the axial positions of the cylinder 20 where the cylinder seal portions 60A, 60B, and 60C are located are all different, and the space between the housing 10 and the cylinder has a stepped shape near the cylinder seal portion 60. However, the cylinder seal portions 60A, 60B, and 60C may be arranged in a straight line in the radial direction of the cylinder 20.

[0037] In the above embodiment 1, the braking device 1 controls the hydraulic pressure of the wheel cylinder WC to apply braking force to the vehicle's wheels W. However, the braking device 1 is not limited to controlling the hydraulic pressure of the wheel cylinder WC. Furthermore, the braking device 1 can also be applied to apply braking force to something other than the vehicle's wheels W.

[0038] 〔summary〕 A braking device according to one aspect of the present disclosure comprises a housing, a cylinder formed separately from the housing and at least a portion of which is inserted into the housing, and a sealing member provided between the cylinder and the housing, which seals the space between the cylinder and the housing in the axial direction of the cylinder. By providing a sealing member to seal the space between the cylinder and the housing in the axial direction of the cylinder, the axial size of the cylinder can be reduced by the size of the sealing member compared to a case where the sealing member is provided to seal the space between the cylinder and the housing in the radial direction of the cylinder.

[0039] In one embodiment of the present disclosure, the braking device, in the embodiment described above, has a cylinder having an opposing portion that faces the housing in the axial direction of the cylinder, and the opposing portion having a sealing portion that sandwiches the sealing member between itself and the housing, and a contact portion that contacts the housing. By configuring the cylinder and housing to come into contact at the contact portion, the amount of deformation of the sealing member caused by the sealing portion sandwiching the sealing member can be easily adjusted.

[0040] A braking device according to one aspect of the present disclosure, in the embodiment, at least one of the cylinder and the housing has a seal housing groove for accommodating a portion of the seal member, the seal housing groove is formed in a portion that contacts the seal member and is recessed in the axial direction of the cylinder. By providing a seal housing groove, which is recessed in the axial direction of the cylinder and accommodates a portion of the seal member, in at least one of the cylinder and the housing, the position of the seal member in the radial direction of the cylinder can be stably determined.

[0041] A braking device according to one aspect of the present disclosure, in the embodiment, the housing has a brake fluid passage, the cylinder divides a hydraulic chamber for filling with brake fluid and a connecting fluid passage connecting the brake fluid passage to the hydraulic chamber, and the connecting fluid passage opens to the opposing portion. Because the connecting fluid passages partitioned within the cylinder open to the opposite side of the cylinder, connecting the brake fluid passages to the opposite side allows for connection between the brake fluid passages and the hydraulic chamber, thus increasing the flexibility in the placement of the brake fluid passages. As a result, this contributes to miniaturization of the braking system.

[0042] A braking device according to one aspect of the present disclosure, in the embodiment, the housing has a brake fluid passage, the cylinder separates a hydraulic chamber for filling with brake fluid and a connecting fluid passage for connecting the brake fluid passage to the hydraulic chamber, and the sealing member is provided between the brake fluid passage and the connecting fluid passage, where a hydraulic pressure smaller than the axial holding force of the cylinder that holds the cylinder in the housing is generated. This disclosure describes a mechanism for sealing the space between a cylinder and a housing in the axial direction of the cylinder. As the internal pressure of the seal increases, a force is applied in the axial direction of the cylinder that widens the gap between the housing and the cylinder. Therefore, by providing a sealing member between the brake fluid passage and the connecting fluid passage, where a fluid pressure smaller than the axial holding force of the cylinder that holds the cylinder in the housing is generated, the axial size of the cylinder can be reduced without degrading the sealing performance between the housing and the cylinder.

[0043] [Additional Notes] This disclosure is not limited to the embodiments described above, 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 this disclosure. [Explanation of Symbols]

[0044] 1 Braking device 10 Housing 11. First brake fluid passage 12. Second brake fluid passage 20 cylinders 20A center shaft 20B outer circumference 21 First connecting liquid channel 22 Second connecting fluid channel 23. Hydraulic chamber 24 Opposing part 25 First area 26 Second area 30 pistons 60, 60A, 60B, 60C, 61 Cylinder seal section 70 Sealing member 71, 73, 81, 83 Contact points 72, 82 seal housing groove

Claims

1. Housing and A cylinder formed separately from the housing, with at least a portion of it inserted into the housing, A braking device comprising a sealing member provided between the cylinder and the housing, which seals the space between the cylinder and the housing in the axial direction of the cylinder.

2. The cylinder has a portion facing the housing in the axial direction of the cylinder, The braking device according to claim 1, wherein the opposing portion has a sealing portion that sandwiches the sealing member between itself and the housing, and a contact portion that contacts the housing.

3. At least one of the cylinder and the housing has a seal housing groove that accommodates a part of the seal member, The braking device according to claim 1, wherein the seal housing groove is formed in a portion that contacts the seal member and is recessed in the axial direction of the cylinder.

4. The housing has a brake fluid passage, The cylinder comprises a hydraulic chamber for filling with brake fluid and a connecting fluid passage for connecting the brake fluid passage to the hydraulic chamber. The braking device according to claim 2, wherein the connecting fluid passage opens to the opposing portion.

5. The housing has a brake fluid passage, The cylinder comprises a hydraulic chamber for filling with brake fluid and a connecting fluid passage for connecting the brake fluid passage to the hydraulic chamber. The braking device according to claim 1, wherein the sealing member is provided between the brake fluid passage and the connecting fluid passage, where a fluid pressure smaller than the axial holding force of the cylinder that holds the cylinder in the housing is generated.

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