Disc brake system

Abstract

As an example, we aim to obtain a disc brake device that can reduce the load on the O-ring. [Solution] A disc brake device according to this embodiment includes, as an example, a caliper body having a hole extending along a central axis and a bore that communicates with the end of the hole in a first axial direction along the central axis and opens to the outside, an inner circumferential surface provided in the bore and facing the central axis, and a side surface provided in the bore and through which the hole opens; a rotating member having an outer circumferential surface extending through the hole and facing the inner circumferential surface; a linear motion member attached to the threads of the rotating member so as to move in the first axial direction or the second axial direction; a piston fitted into the bore so as to be movable along the central axis; and an O-ring that contacts the inner circumferential surface, the side surface, and the outer circumferential surface and seals the space between the inner circumferential surface and the outer circumferential surface, wherein a groove spaced apart from the hole is provided on the side surface.

Description

Technical Field

[0001] Embodiments of the present invention relate to a disk brake device.

Background Art

[0002] Conventionally, a disk brake device including a caliper body, a piston fitted into the bore of the caliper body, and a rotary-linear motion conversion mechanism for driving the piston is known. The rotary-linear motion conversion mechanism has, for example, a rotating member rotated by a motor and a linear motion member that biases the piston by converting the rotation of the rotating member into linear motion.

[0003] The disk brake device can also drive the piston by the pressure of the brake fluid in the bore. The disk brake device further has an O-ring that restricts, for example, the flow of the brake fluid in the bore toward the motor or the reducer. The O-ring is disposed around the rotating member (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional configuration, the O-ring may be pushed by the pressure of the brake fluid in the bore and enter the narrow gap between the rotating member and the caliper body. In this case, in the gap, the O-ring receives a load by contacting the stationary caliper body and the rotating rotating member.

[0006] Therefore, the present invention has been made in view of the above, and provides a disk brake device capable of reducing the load received by the O-ring.

Means for Solving the Problems

[0007] A disc brake device according to an embodiment of the present invention includes, as an example, a caliper body having a hole extending along a central axis, a bore communicating with the end of the hole in a first axial direction along the central axis and opening to the outside, an inner circumferential surface provided in the bore and facing the central axis, and a side surface provided in the bore and through which the hole opens; a rotating member having an outer circumferential surface extending through the hole and facing the inner circumferential surface, and a screw thread located in the bore, and rotatable around the central axis; and a rotating member located in the bore and corresponding to the rotation of the screw thread around the central axis. The brake system comprises a linear motion member attached to the screw threads so as to move in the axial direction 1 or in the second axial direction opposite to the first axial direction; a piston fitted into the bore so as to be movable along the central axis and configured to be biased toward the brake pad by the linear motion member moving in the first axial direction, and also configured to be biased toward the brake pad by the pressure of the brake fluid in the bore; and an O-ring that contacts the inner circumferential surface, the side surface, and the outer circumferential surface, sealing the space between the inner circumferential surface and the outer circumferential surface, wherein a groove spaced apart from the hole is provided on the side surface. For example, when the pressure of the brake fluid in the bore increases, the pressure presses the O-ring against the side surface. The O-ring, pressed by the pressure, elastically deforms so as to enter not only the hole opening in the side surface but also the groove. As a result, compared to the case without a groove, the stress on the O-ring is distributed between the part of the O-ring that enters the hole and the part that enters the groove. Therefore, the disc brake device can reduce the load on the rotating member by having the portion of the O-ring that enters the hole come into contact with the outer surface of the rotating member. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view showing a disc brake device according to the first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing a portion of the EPB of the first embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing a portion of the elastically deformed EPB of the O-ring in the first embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view showing a portion of the EPB according to the second embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing a portion of the elastically deformed EPB of the O-ring in the second embodiment. [Modes for carrying out the invention]

[0009] (First Embodiment) The first embodiment will be described below with reference to Figures 1 to 3. Note that in this specification, the components of the embodiment and their descriptions may be described using multiple expressions. The components and their descriptions are examples and are not limited by the expressions used herein. Components may also be identified by names different from those used herein. Furthermore, components may also be described using expressions different from those used herein.

[0010] In the following explanation, “suppress” is defined, for example, to prevent the occurrence of an event, action, or effect, or to reduce the degree of an event, action, or effect. Also, in the following explanation, “restrict” is defined, for example, to prevent movement or rotation, or to permit movement or rotation within a predetermined range while preventing movement or rotation beyond that predetermined range.

[0011] Figure 1 is a schematic cross-sectional view showing a disc brake device 10 according to the first embodiment. The disc brake device 10 is mounted on a vehicle 1 such as a four-wheeled automobile. The disc brake device 10 may also be mounted on other devices. The disc brake device 10 may also be referred to as a braking device. As shown in Figure 1, the disc brake device 10 has a disc rotor 11 and an electric parking brake (EPB) 12.

[0012] The disc rotor 11 is formed in a disc shape and is connected to the axle of the vehicle 1 via, for example, a hat-shaped hub. Therefore, the disc rotor 11 rotates integrally with the wheels of the vehicle 1 relative to the vehicle body.

[0013] The EPB12 can operate as both a hydraulic service brake and an electric brake. The EPB12 in this embodiment includes a brake caliper 21, a pair of brake pads 22, and a drive unit 23. The drive unit 23 may also be referred to as a motor gear unit (MGU).

[0014] For example, the brake caliper 21 and brake pad 22 constitute a hydraulic service brake, and the brake caliper 21, brake pad 22, and drive unit 23 constitute an electric brake. The EPB12 is configured so that the braking state due to the electric brake function is maintained when parked. The electric brake may also operate when driving or when stopped.

[0015] The brake caliper 21 is, for example, a floating caliper. The brake caliper 21 is positioned to straddle the disc rotor 11. The brake caliper 21 includes a mounting 31, a caliper body 32, a piston 33, a piston seal 34, a rotation-to-linear motion conversion mechanism 35, and an O-ring 36. The O-ring 36 may also be called a seal ring.

[0016] The mounting 31 is fixed to a non-rotating part of the vehicle 1. For example, the mounting 31 is attached to the knuckle of the vehicle 1. The mounting 31 supports the brake pad 22 and the caliper body 32 so that they can move along the central axis of the disc rotor 11.

[0017] The caliper body 32 is made of a metal such as an aluminum alloy. The caliper body 32 has a cylinder 41, claws 42, and a bridge 43. However, the caliper body 32 is not limited to this example.

[0018] The cylinder 41 is provided with a bore 45 and an insertion hole 46. The insertion hole 46 is an example of a hole. The bore 45 and the insertion hole 46 are each a hole having a substantially circular cross-section that extends along the central axis Ax.

[0019] The central axis Ax is the common central axis of the bore 45 and the insertion hole 46. The central axis Ax extends substantially parallel to the central axis of the disk rotor 11. Note that the central axis of the bore 45 and the central axis of the insertion hole 46 may be offset from each other.

[0020] Hereinafter, the direction along the central axis Ax is referred to as the axial direction, the direction orthogonal to the central axis Ax is referred to as the radial direction, and the direction around the central axis Ax is referred to as the circumferential direction. The axial direction is substantially along the vehicle width of the vehicle 1 and includes an outer direction Do and an inner direction Di. The outer direction Do is one direction along the central axis Ax and is an example of the first axial direction. The inner direction Di is the opposite direction of the outer direction Do and is an example of the second axial direction. For example, the outer direction Do is the direction toward the outside of the vehicle 1, and the inner direction Di is the direction toward the inside of the vehicle 1.

[0021] The cylinder 41 has an outer end face 41a and an inner end face 41b. The outer end face 41a is provided at the end of the cylinder 41 in the outer direction Do. The inner end face 41b is provided at the end of the cylinder 41 in the inner direction Di.

[0022] The bore 45 opens to the outer end face 41a. That is, the bore 45 is recessed from the outer end face 41a in the inner direction Di and opens to the outside of the caliper body 32. The insertion hole 46 opens to the inner end face 41b. The end of the bore 45 in the inner direction Di and the end of the insertion hole 46 in the outer direction Do communicate with each other.

[0023] The cylinder 41 further has a bore inner surface 51 and a hole inner surface 52. The bore inner surface 51 is the inner surface of the cylinder 41 that defines the bore 45. The hole inner surface 52 is the inner surface of the cylinder 41 that defines the insertion hole 46.

[0024] Figure 2 is a schematic cross-sectional view showing a part of the EPB12 of the first embodiment. The inner surface 51 of the bore has a sliding surface 51a and a bottom surface 51b as shown in Figure 1, and an inner circumferential surface 51c and a side surface 51d as shown in Figure 2. That is, the sliding surface 51a, the bottom surface 51b, the inner circumferential surface 51c, and the side surface 51d are provided in the bore 45.

[0025] As shown in Figure 1, the sliding surface 51a is a substantially cylindrical curved surface extending along the central axis Ax and facing the central axis Ax. The end of the sliding surface 51a in the outward direction Do is connected to the outer end surface 41a. The end of the sliding surface 51a in the inward direction Di is connected to the end of the bottom surface 51b on the radially outer side. The bottom surface 51b is formed to be substantially flat and faces outward direction Do. Note that the bottom surface 51b is not limited to this example and may have irregularities or face other directions.

[0026] As shown in Figure 2, the inner circumferential surface 51c is connected to the end of the bottom surface 51b on the radially inner side. The inner circumferential surface 51c is a substantially cylindrical curved surface that extends along the central axis Ax and faces the central axis Ax. The inner circumferential surface 51c may also be formed into other shapes, such as a cone.

[0027] The end of the side surface 51d in the inward direction Di is connected to the end of the inner circumferential surface 51c on the radially outward side. The side surface 51d is formed to be substantially flat and faces outward direction Do. Note that the side surface 51d is not limited to this example and may have irregularities or face other directions. The side surface 51d is provided at the end of the bore 45 in the inward direction Di. The end of the insertion hole 46 in the outward direction Do opens into the side surface 51d.

[0028] The inner surface 52 of the bore is a substantially cylindrical curved surface extending along the central axis Ax and facing the central axis Ax. The end of the inner surface 52 of the bore in the outward direction Do is connected to the end of the side surface 51d on the radially inward side. The end of the inner surface 52 of the bore in the outward direction Do may be chamfered as shown in Figure 2. The diameter of the inner circumferential surface 51c of the bore inner surface 51 is smaller than the diameter of the sliding surface 51a and larger than the diameter of the inner surface 52 of the bore.

[0029] The cylinder 41 is further provided with a seal groove 55 and a flow path 56 as shown in Figure 1, and a groove 57 as shown in Figure 2. As shown in Figure 1, the seal groove 55 is provided on the sliding surface 51a and extends in the circumferential direction. The piston seal 34 is fitted into the seal groove 55. The flow path 56 is spaced inward Di from the seal groove 55 and opens, for example, to the sliding surface 51a. That is, the flow path 56 communicates with the bore 45. Brake fluid is supplied to or discharged from the bore 45 through the flow path 56.

[0030] As shown in Figure 2, the groove 57 is provided at the end of the radially outer side surface 51d. Therefore, the groove 57 is located between the inner circumferential surface 51c and the side surface 51d. The groove 57 may be spaced apart from the radially outer side surface 51d. The groove 57 is spaced radially outward from the insertion hole 46.

[0031] In this embodiment, the groove 57 is recessed inward Di from the side surface 51d along the inner circumferential surface 51c. As a result, the groove 57 extends in the circumferential direction, and the outer diameter of the groove 57 is approximately equal to the diameter of the inner circumferential surface 51c.

[0032] The depth of the groove 57 in the axial direction increases toward the radially outward direction. That is, as shown in Figure 2, the groove 57 has a cross-section of a roughly right triangle. For this reason, the cylinder 41 further has an inner circumferential surface 57a and an inclined surface 57b that define the groove 57. Note that the cross-section of the groove 57 may be formed in other shapes.

[0033] The inner circumferential surface 57a is continuous with the inner circumferential surface 51c of the bore inner surface 51. That is, the inner circumferential surface 57a is a substantially cylindrical curved surface extending along the central axis Ax, and its diameter is approximately equal to the inner circumferential surface 51c of the bore inner surface 51. Note that the inner circumferential surface 57a is not limited to this example.

[0034] The inclined surface 57b extends obliquely with respect to the central axis Ax between the end of the inner circumferential surface 57a in the inward direction Di and the end of the side surface 51d on the radially outward side. The inclined surface 57b is a substantially conical curved surface that tapers outward in the outward direction Do.

[0035] The width Lw of the groove 57 in the radial direction is greater than the depth Ld of the groove 57 in the axial direction. In this embodiment, the width Lw is the distance between the inner circumferential surface 57a and the edge of the radially outer side surface 51d. For example, the width Lw is approximately 1.0 mm and the depth Ld is approximately 0.29 mm. The width Lw is set to, for example, 0.5 mm or more. Note that the width Lw and depth Ld are not limited to this example.

[0036] As shown in Figure 1, the claws 42 are spaced outward from the cylinder 41 in the direction Do. The claws 42 are formed in a plate shape and are positioned approximately perpendicular to the axial direction. The bridge 43 extends across the disc rotor 11 and connects the cylinder 41 and the claws 42.

[0037] The piston 33 is formed, for example, in a substantially cylindrical shape that is open inward in the direction Di. The piston 33 has an outer circumferential surface 33a. The outer circumferential surface 33a is a substantially cylindrical curved surface that extends along the central axis Ax.

[0038] The piston 33 is fitted into the bore 45 so as to be movable along its central axis Ax. In other words, the piston 33 is housed in the bore 45. A portion of the piston 33 may be located outside the bore 45. The diameter of the outer circumferential surface 33a of the piston 33 is smaller than the diameter of the sliding surface 51a of the inner surface 51 of the bore. The outer circumferential surface 33a and the sliding surface 51a face each other.

[0039] As the piston 33 fits into the bore 45, the piston seal 34, fitted into the seal groove 55, comes into contact with the outer circumferential surface 33a of the piston 33. This causes the piston seal 34 to seal the gap between the piston 33 and the cylinder 41 in a watertight manner.

[0040] The piston 33 and cylinder 41 define a pressure chamber Rp, which is part of the bore 45. The pressure chamber Rp communicates with the flow path 56. The piston seal 34 provides a watertight seal between the pressure chamber Rp and the outside of the cylinder 41.

[0041] The rotary-to-linear motion conversion mechanism 35 includes a rotating member 61, a linear motion member 62, and a bearing 63. The rotating member 61 may also be referred to as a shaft. The linear motion member 62 may also be referred to as a nut. At least a portion of the rotating member 61, at least a portion of the linear motion member 62, and the bearing 63 are located in the pressure chamber Rp of the bore 45.

[0042] The rotating member 61 is supported by the cylinder 41 so as to be rotatable about a central axis Ax. The rotating member 61 has a flange 65, a coupling shaft 66, and a threaded shaft 67. The flange 65 and the threaded shaft 67 are located in the bore 45. The coupling shaft 66 is located, at least partially, in the insertion hole 46.

[0043] The flange 65 is formed in a disc shape approximately perpendicular to the central axis Ax. The outer diameter of the flange 65 is smaller than the diameter of the sliding surface 51a. The flange 65 is supported on the bottom surface 51b via a bearing 63. The bearing 63 is, for example, a thrust bearing. The flange 65 is located between the coupling shaft 66 and the screw shaft 67.

[0044] Each of the coupling shaft 66 and the screw shaft 67 is formed in a substantially cylindrical shape extending along the central axis Ax. In this embodiment, the central axis Ax is also the central axis of the flange 65, the coupling shaft 66, and the screw shaft 67.

[0045] The coupling shaft 66 extends inward Di from the flange 65 and is fitted into the insertion hole 46. As shown in Figure 2, the coupling shaft 66 has an outer circumferential surface 66a. The outer circumferential surface 66a is a substantially cylindrical curved surface that extends along the central axis Ax. The outer circumferential surface 66a extends through the insertion hole 46.

[0046] The diameter of the outer circumferential surface 66a is smaller than the diameter of the inner circumferential surface 51c of the inner bore surface 51, and also smaller than the diameter of the inner hole surface 52. The outer circumferential surface 66a of the coupling shaft 66 and the inner circumferential surface 51c of the cylinder 41 face each other. Furthermore, the outer circumferential surface 66a of the coupling shaft 66 and the inner hole surface 52 of the cylinder 41 face each other.

[0047] A gap Gc is provided between the outer circumferential surface 66a of the coupling shaft 66 and the inner surface 52 of the hole in the cylinder 41. The gap Gc is part of the insertion hole 46. The width Lg of the gap Gc in the radial direction is smaller than the width Lw of the groove 57 in the radial direction. The width Lg is the distance between the end of the inner side surface 51d in the radial direction and the outer circumferential surface 66a of the coupling shaft 66.

[0048] If the end of the inner surface 52 of the hole in the outward direction Do is chamfered as shown in Figure 2, the width Lg is also the maximum distance between the chamfered portion of the inner surface 52 of the hole and the outer surface 66a of the coupling shaft 66.

[0049] An annular space S is provided between the outer circumferential surface 66a of the coupling shaft 66 and the inner circumferential surface 51c of the cylinder 41. The space S is defined, for example, by the inner circumferential surface 51c, the side surface 51d, and the outer circumferential surface 66a, and is located between the pressure chamber Rp and the gap Gc. An O-ring 36 is fitted into the space S.

[0050] In its natural state, without any external force acting, the diameter (wire diameter) of the cross-section of the O-ring 36 is greater than the distance Ls between the inner surface 51c and the outer surface 66a. The distance Ls is the width of the space S in the radial direction. For example, the wire diameter of the O-ring 36 is approximately 2.6 mm, and the distance Ls is approximately 2.0 mm. Note that the wire diameter and distance Ls are not limited to this example.

[0051] The O-ring 36 is in contact with the inner circumferential surface 51c and side surface 51d of the cylinder 41 and the outer circumferential surface 66a of the coupling shaft 66. The O-ring 36 is compressed radially between the outer circumferential surface 66a of the coupling shaft 66 and the inner circumferential surface 51c of the cylinder 41. As a result, the O-ring 36 watertight seals the space S.

[0052] As shown in Figure 1, the screw shaft 67 of the rotating member 61 extends outward from the flange 65 in the direction Do. The screw shaft 67 has an outer circumferential surface 67a and an external thread (bolt thread) 67b. That is, the external thread 67b is located in the pressure chamber Rp of the bore 45. The external thread 67b is an example of a screw thread.

[0053] The outer circumferential surface 67a is a substantially cylindrical curved surface extending along the central axis Ax. The outer circumferential surface 67a faces the sliding surface 51a of the cylinder 41 at intervals. The male screw 67b is provided on the outer circumferential surface 67a.

[0054] The linear motion member 62 is attached to the male thread 67b of the rotating member 61. The linear motion member 62 is formed in a substantially cylindrical shape extending along the central axis Ax. The linear motion member 62 has an inner circumferential surface 62a and an internal thread (nut thread) 62b.

[0055] The inner circumferential surface 62a is a substantially cylindrical curved surface extending along the central axis Ax and facing the central axis Ax. The female thread 62b is provided on the inner circumferential surface 62a. The screw shaft 67 of the rotating member 61 is fitted inside the linear motion member 62, and the female thread 62b and the male thread 67b engage. In this way, the linear motion member 62 is attached to the male thread 67b.

[0056] The female thread 62b and the male thread 67b may be indirectly connected to each other. For example, the rotary-to-linear motion conversion mechanism 35 may be a ball screw in which the female thread 62b and the male thread 67b are connected to each other via balls.

[0057] The linear motion member 62 and at least a portion of the screw shaft 67 are housed inside the piston 33. The linear motion member 62 is attached to the piston 33 with its rotation restricted, for example, around the central axis Ax. Therefore, the linear motion member 62 moves outward (Do) or inward (Di) in response to the rotation of the male screw 67b. The piston 33 can move axially relative to the linear motion member 62.

[0058] A pair of brake pads 22 are positioned between the cylinder 41 and the pawl 42. The pair of brake pads 22 are spaced apart from each other in the axial direction. The disc rotor 11 is positioned between the pair of brake pads 22. One brake pad 22 contacts the piston 33. The other brake pad 22 contacts the pawl 42.

[0059] The drive unit 23 rotates the rotating member 61. The drive unit 23 includes, for example, a case 71, a motor 72, and a reduction gear 73. The drive unit 23 may have other components, or the reduction gear 73 may be omitted.

[0060] The case 71 is attached to the cylinder 41 so as to cover the inner end face 41b of the cylinder 41. A gear chamber Rg is provided inside the case 71. The gear chamber Rg communicates with the insertion hole 46. That is, the insertion hole 46 connects the pressure chamber Rp and the gear chamber Rg. The O-ring 36 seals the space S watertight, thereby restricting the flow of brake fluid from the pressure chamber Rp into the gear chamber Rg through the insertion hole 46.

[0061] The motor 72 is mounted in the case 71. The reducer 73 is located in the gear chamber Rg. The reducer 73 has, for example, a plurality of gears 75 and a planetary gear mechanism 76. The plurality of gears 75 mesh with each other in a manner that can transmit rotation. One of the plurality of gears 75 is connected to the motor shaft of the motor 72. Another of the plurality of gears 75 is connected to, for example, the sun gear of the planetary gear mechanism 76. The planetary carrier of the planetary gear mechanism 76 is connected to the coupling shaft 66 of the rotating member 61.

[0062] The motor 72 is driven by drive power based on a control signal, and rotates one gear 75. Multiple gears 75 and the planetary gear mechanism 76 reduce the rotation input from the motor 72 and transmit it to the rotating member 61. As a result, the drive device 23 rotates the rotating member 61 around the central axis Ax.

[0063] Brake fluid fills the pressure chamber Rp. For example, the master cylinder or pump of the disc brake device 10 increases the pressure in the pressure chamber Rp through the passage 56 in response to the operation of the brake pedal or control by the ECU.

[0064] The pressure of the brake fluid in the pressure chamber Rp of the bore 45 biases the piston 33 toward the brake pad 22. This causes the piston 33 to move outward Do, pressing one of the brake pads 22 against the disc rotor 11.

[0065] When one brake pad 22 is pressed against the disc rotor 11, the caliper body 32 moves inward Di due to the recoil. As a result, the claws 42 of the caliper body 32 push the other brake pad 22 inward Di. This presses the pair of brake pads 22 against the disc rotor 11.

[0066] The pair of brake pads 22 receive a circumferential force from the disc rotor 11 due to friction between the brake pads 22 and the disc rotor 11. The mounting 31 receives the braking force (braking torque) transmitted through the pair of brake pads 22 and transmits it to the vehicle body 1. As a result, the disc brake device 10 brakes the disc rotor 11 as a service brake.

[0067] The piston seal 34 has a retract function in which, as the pressure in the pressure chamber Rp decreases, the elastic force pulls the piston 33 inward towards the pressure chamber Rp Di, separating the piston 33 from the brake pad 22. In other words, as the pressure in the pressure chamber Rp decreases, the pressure of the piston 33 on the brake pad 22 is released, and the pressure of the piston 33 on the brake pad 22 on the disc rotor 11 is released. As a result, the disc brake device 10 achieves a brake release state in service brake mode.

[0068] When the drive unit 23 rotates the rotating member 61 in one direction about the central axis Ax, the linear motion member 62 moves in a straight line outward Do, pushing the piston 33. In other words, the piston 33 is biased toward the brake pad 22 by the linear motion member 62 moving outward Do. As a result, the piston 33 moves outward Do, pressing the brake pad 22 against the disc rotor 11.

[0069] Similar to when the service brake is applied, the caliper body 32 moves inward (Di) due to the recoil, and the pair of brake pads 22 are pressed against the disc rotor 11. As a result, the disc brake device 10 obtains a braking state by electric brakes, in which the wheel of the vehicle 1, which rotates integrally with the disc rotor 11, is braked.

[0070] When the drive unit 23 rotates the rotating member 61 in the opposite direction around the central axis Ax, the linear motion member 62 moves inward in the direction Di. The piston 33 moves inward in the direction Di due to the retract function of the piston seal 34. The pressing force of the piston 33 on the brake pad 22 decreases, and the pressing of the brake pad 22 against the disc rotor 11 by the piston 33 is released. As a result, the disc brake device 10 obtains a state of release from braking by the electric brake (non-braking state).

[0071] Figure 3 is a schematic cross-sectional view showing a portion of the EPB12 with the O-ring 36 elastically deformed in the first embodiment. The pressure of the brake fluid in the pressure chamber Rp of the bore 45 pushes the O-ring 36 inward Di. As a result, the O-ring 36 is pressed against the side surface 51d of the cylinder 41. Depending on the pressure of the brake fluid in the pressure chamber Rp, the O-ring 36 may elastically deform so that it partially fits into the groove 57 and the gap Gc.

[0072] For example, a portion of the O-ring 36 undergoes elastic deformation to fit into the gap Gc, generating tensile stress. In the gap Gc, the O-ring 36 contacts the inner surface 52 of the hole in the cylinder 41 and the outer surface 66a of the coupling shaft 66 of the rotating member 61.

[0073] If the stress on the O-ring 36 in the gap Gc is high, the O-ring 36 will twist around the central axis Ax when the rotating member 61 rotates relative to the cylinder 41. However, the O-ring 36 in this embodiment partially undergoes elastic deformation so as to fit into the groove 57. As a result, the stress is distributed, and the stress on the O-ring 36 in the gap Gc is reduced.

[0074] In this embodiment, the volume of the portion of the O-ring 36 that fits into the groove 57 is larger than the volume of the portion of the O-ring 36 that fits into the gap Gc. Therefore, the stress on the O-ring 36 in the gap Gc is reduced.

[0075] When the stress on the O-ring 36 in the gap Gc is low, the O-ring 36 can slide along the outer surface 66a of the coupling shaft 66. As a result, the O-ring 36 becomes less prone to twisting around the central axis Ax, and is less susceptible to wear and damage.

[0076] A portion of the O-ring 36 that is fitted into the groove 57 also experiences stress. However, this portion of the O-ring 36 that is fitted into the groove 57 contacts the cylinder 41 but does not contact the rotating member 61. Therefore, even if the stress on the O-ring 36 in the groove 57 increases, the O-ring 36 is less likely to wear down or be damaged.

[0077] In the disc brake device 10 according to the first embodiment described above, the caliper body 32 has an inner circumferential surface 51c provided in the bore 45 and facing the central axis Ax, and a side surface 51d provided in the bore 45 and through which the insertion hole 46 opens. The rotating member 61 has an outer circumferential surface 66a that extends through the insertion hole 46 and faces the inner circumferential surface 51c. The O-ring 36 contacts the inner circumferential surface 51c, the side surface 51d, and the outer circumferential surface 66a, sealing the space S between the inner circumferential surface 51c and the outer circumferential surface 66a. A groove 57 spaced apart from the insertion hole 46 is provided on the side surface 51d.

[0078] As the pressure of the brake fluid in the bore 45 increases, this pressure presses the O-ring 36 against the side surface 51d. The O-ring 36, pressed by the pressure, elastically deforms so as to enter not only the gap Gc of the through hole 46 opening in the side surface 51d, but also the groove 57. As a result, the stress on the O-ring 36 is distributed between the portion of the O-ring 36 that enters the through hole 46 and the portion that enters the groove 57, compared to the case without the groove 57. Therefore, the disc brake device 10 can reduce the load on the portion of the O-ring 36 that enters the through hole 46 that comes into contact with the outer surface 66a of the rotating member 61, thereby suppressing wear or damage to the O-ring 36.

[0079] In the radial direction perpendicular to the central axis Ax, the width Lw of the groove 57 is greater than the width Lg of the gap Gc between the side surface 51d and the outer surface 66a. A portion of the O-ring 36, pressed by pressure, enters the gap Gc of the insertion hole 46. However, because the width Lw of the groove 57 is greater than the width Lg of the gap Gc between the side surface 51d and the outer surface 66a, the O-ring 36 is more likely to enter the groove 57 than the insertion hole 46. As a result, the stress on the portion of the O-ring 36 that enters the insertion hole 46 is reduced compared to the case where the width Lg of the gap Gc between the side surface 51d and the outer surface 66a is greater than the width Lw of the groove 57. Therefore, the disc brake device 10 can reduce the load on the portion of the O-ring 36 that enters the insertion hole 46 by contacting the outer surface 66a of the rotating member 61, and consequently, can suppress wear or damage to the O-ring 36.

[0080] The groove 57 is provided at the end of the side surface 51d on the radially outer side perpendicular to the central axis Ax, and is located between the inner circumferential surface 51c and the side surface 51d. In other words, the groove 57 is spaced as far away from the insertion hole 46 as possible on the side surface 51d. As a result, the disc brake device 10 can better distribute the stress on the O-ring 36 between the portion of the O-ring 36 that enters the insertion hole 46 and the portion that enters the groove 57.

[0081] (Second embodiment) A second embodiment will be described below with reference to Figures 4 and 5. In the following description of the embodiments, components having the same function as those already described will be denoted by the same reference numerals as those previously described, and their description may be omitted. Furthermore, multiple components denoted by the same reference numerals do not necessarily share all functions and properties, and may have different functions and properties depending on the embodiment.

[0082] Figure 4 is a schematic cross-sectional view showing a part of the EPB12 according to the second embodiment. As shown in Figure 4, the EPB12 of the second embodiment further includes a bush 200. The bush 200 is made of resin or metal. The bush 200 has a cylindrical portion 201 and a flange portion 202.

[0083] The cylindrical portion 201 is formed in a substantially cylindrical shape extending along the central axis Ax. Therefore, an inner hole 205 is provided inside the cylindrical portion 201. The inner hole 205 is a hole that extends along the central axis Ax. The cylindrical portion 201 has an inner surface 205a that defines the inner hole 205. The inner surface 205a is a substantially cylindrical curved surface that extends along the central axis Ax and faces the central axis Ax.

[0084] The cylindrical portion 201 is fitted into the through hole 46 of the cylinder 41 and extends through the through hole 46. The coupling shaft 66 of the rotating member 61 extends through the inner hole 205 of the cylindrical portion 201. Therefore, in the through hole 46, the cylindrical portion 201 is positioned between the inner surface 52 of the hole in the cylinder 41 of the caliper body 32 and the outer circumferential surface 66a of the coupling shaft 66 of the rotating member 61.

[0085] The diameter of the inner surface 205a of the cylindrical portion 201 is larger than the diameter of the outer surface 66a of the coupling shaft 66. Therefore, the inner surface 205a of the cylindrical portion 201 and the outer surface 66a of the coupling shaft 66 face each other with a gap Gb between them. The gap Gb connects the space S and the gear chamber Rg.

[0086] The flange portion 202 is formed in a substantially disc shape perpendicular to the axial direction and is located in the space S of the bore 45. The flange portion 202 protrudes radially outward from the end of the cylindrical portion 201 in the outward direction Do. That is, the flange portion 202 extends from the cylindrical portion 201 toward the inner circumferential surface 51c of the cylinder 41. The flange portion 202 is located between the O-ring 36 and the side surface 51d of the cylinder 41.

[0087] The flange portion 202 has a support surface 202a, an outer edge 202b, and a slope 202c. The support surface 202a is formed to be substantially flat and faces outward in the direction Do. The support surface 202a is located at the end of the flange portion 202 in the outward direction Do.

[0088] The outer edge 202b is located at the end of the flange 202 on the radially outward side. The outer edge 202b extends circumferentially and faces radially outward. The outer edge 202b of the flange 202 and the inner circumferential surface 51c of the cylinder 41 face each other with a gap between them.

[0089] The inclined surface 202c extends obliquely with respect to the central axis Ax between the end of the support surface 202a on the radially outward side and the end of the outer edge 202b in the outward direction Do. The inclined surface 202c is a roughly conical curved surface that tapers outward in the outward direction Do. Note that the inclined surface 202c may be omitted.

[0090] The flange portion 202 is spaced apart from the inner circumferential surface 51c of the cylinder 41. An outer groove So is provided between the inner circumferential surface 51c and the flange portion 202. The outer groove So is the space between the inner circumferential surface 51c and the flange portion 202. In the assembled EPB12, the outer groove So becomes a groove that is recessed inward Di from the support surface 202a of the flange portion 202 and extends in the circumferential direction.

[0091] In the radial direction, the distance Lo between the inner circumferential surface 51c and the end of the support surface 202a on the radially outer side is greater than the thickness Lt of the flange portion 202 in the axial direction. Distance Lo is the width of the outer groove So that opens into the support surface 202a. Distance Lo is set to, for example, 0.5 mm or more. For example, if the thickness Lt is 0.7 mm, then distance Lo is 0.7 mm or more.

[0092] In this embodiment, distance Lo is the maximum distance between the inner circumferential surface 51c and the inclined surface 202c in the radial direction. However, if the inclined surface 202c is omitted, distance Lo is, for example, the distance between the inner circumferential surface 51c and the outer edge 202b in the radial direction.

[0093] The distance Lo is greater than the width Lb of the gap Gb in the radial direction. The width Lb is the distance between the end of the support surface 202a on the radially inner side and the outer circumferential surface 66a of the coupling shaft 66. Also, the width Lb is less than the thickness Lt.

[0094] Figure 5 is a schematic cross-sectional view showing a portion of the EPB12 in which the O-ring 36 of the second embodiment has undergone elastic deformation. The pressure of the brake fluid in the pressure chamber Rp of the bore 45 pushes the O-ring 36 inward Di. As a result, the O-ring 36 comes into contact with and is pressed against the support surface 202a of the flange portion 202. Depending on the pressure of the brake fluid in the pressure chamber Rp, the O-ring 36 may elastically deform so that it partially enters the outer groove So and the gap Gb.

[0095] For example, a portion of the O-ring 36 undergoes elastic deformation to fit into the gap Gb, generating tensile stress. In the gap Gb, the O-ring 36 contacts the inner surface 205a of the cylindrical portion 201 of the bush 200 and the outer circumferential surface 66a of the coupling shaft 66 of the rotating member 61.

[0096] If the stress on the O-ring 36 in the gap Gb is high, the O-ring 36 will twist around the central axis Ax when the rotating member 61 rotates relative to the cylinder 41. However, the O-ring 36 in this embodiment partially undergoes elastic deformation so as to fit into the outer groove So. As a result, the stress is distributed, and the stress on the O-ring 36 in the gap Gb is reduced.

[0097] In this embodiment, the volume of the portion of the O-ring 36 that fits into the outer groove So is larger than the volume of the portion of the O-ring 36 that fits into the gap Gb. Therefore, the stress on the O-ring 36 in the gap Gb is reduced.

[0098] When the stress on the O-ring 36 in the gap Gb is low, the O-ring 36 slides along the outer surface 66a of the coupling shaft 66. As a result, the O-ring 36 becomes less prone to twisting around the central axis Ax, and is less susceptible to wear and damage.

[0099] A portion of the O-ring 36 that has entered the outer groove So also experiences stress. However, the portion of the O-ring 36 that has entered the outer groove So contacts the cylinder 41 and the bush 200, but does not contact the rotating member 61. Therefore, even if the stress on the O-ring 36 in the outer groove So increases, the O-ring 36 is unlikely to wear down or be damaged.

[0100] In the disc brake device 10 of the second embodiment described above, the bush 200 has a cylindrical portion 201 that extends through the insertion hole 46 and is located between the outer peripheral surface 66a and the caliper body 32 in the insertion hole 46, and a flange portion 202 that is located in the bore 45 and extends from the cylindrical portion 201 toward the inner peripheral surface 51c. The flange portion 202 has a support surface 202a that contacts the O-ring 36. An outer groove So is provided between the inner peripheral surface 51c and the flange portion 202, recessed from the support surface 202a. The distance Lo between the inner peripheral surface 51c and the support surface 202a in the radial direction perpendicular to the central axis Ax is greater than the thickness Lt of the flange portion 202 along the central axis Ax.

[0101] As the pressure of the brake fluid in the bore 45 increases, this pressure presses the O-ring 36 against the support surface 202a. The O-ring 36, pressed by the pressure, elastically deforms so as to enter not only the gap Gb between the support surface 202a and the outer surface 66a, but also the outer groove So. Because the width of the outer groove So is set to be large, a larger portion of the O-ring 36 enters the outer groove So. As a result, the stress on the O-ring 36 is distributed between the portion that enters the gap Gb and the portion that enters the outer groove So, compared to the case where there is no outer groove So. Therefore, the disc brake device 10 can reduce the load on the portion of the O-ring 36 that enters the gap Gb and contacts the outer surface 66a of the rotating member 61, and consequently suppress wear or damage to the O-ring 36.

[0102] In the radial direction, the distance Lo between the inner circumferential surface 51c and the support surface 202a is greater than the width Lb between the support surface 202a and the outer circumferential surface 66a. A portion of the O-ring 36, pressed by pressure, enters the gap Gb between the support surface 202a and the outer circumferential surface 66a. However, because the distance Lo between the inner circumferential surface 51c and the support surface 202a is greater than the width Lb between the support surface 202a and the outer circumferential surface 66a, the O-ring 36 is more likely to enter the outer groove So than the gap Gb. As a result, the stress on the portion of the O-ring 36 that enters the gap Gb is reduced compared to the case where the width Lb between the support surface 202a and the outer circumferential surface 66a is greater than the distance Lo between the inner circumferential surface 51c and the support surface 202a. Therefore, the disc brake device 10 can reduce the load on the O-ring 36 that comes into contact with the outer circumferential surface 66a of the rotating member 61, thereby preventing the O-ring 36 from wearing down or being damaged.

[0103] In the embodiments described above, the O-ring 36 contacts the outer circumferential surface 66a of the coupling shaft 66 of the rotating member 61. However, the rotating member 61 may have, for example, a body having a flange 65, a coupling shaft 66, and a screw shaft 67, and a seal shaft surrounding the coupling shaft 66. In this case, the O-ring 36 contacts the outer circumferential surface of the seal shaft instead of the outer circumferential surface 66a of the coupling shaft 66. In this structure, the seal shaft is formed, for example, in a substantially cylindrical shape extending along a central axis Ax, and can rotate independently of the body around the central axis Ax relative to the cylinder 41.

[0104] A disc brake device according to at least one embodiment described above includes, as an example, a caliper body having a hole extending along a central axis and a bore that communicates with the end of the hole in a first axial direction along the central axis and opens to the outside, an inner circumferential surface provided in the bore and facing the central axis, and a side surface provided in the bore and through which the hole opens; a rotating member having an outer circumferential surface extending through the hole and facing the inner circumferential surface, and a screw thread located in the bore, and rotatable around the central axis; and a component located in the bore that controls the rotation of the screw thread around the central axis. The brake system includes: a linear motion member attached to the screw threads so as to move in the first axial direction or in a second axial direction opposite to the first axial direction; a piston fitted into the bore so as to be movable along the central axis and configured to be biased toward the brake pad by the linear motion member moving in the first axial direction, and also configured to be biased toward the brake pad by the pressure of the brake fluid in the bore; and an O-ring that contacts the inner circumferential surface, the side surface, and the outer circumferential surface, sealing the space between the inner circumferential surface and the outer circumferential surface, wherein a groove spaced apart from the hole is provided on the side surface. For example, when the pressure of the brake fluid in the bore increases, the pressure presses the O-ring against the side surface. The O-ring, pressed by the pressure, elastically deforms so as to enter not only the hole opening in the side surface but also the groove. As a result, compared to the case without a groove, the stress on the O-ring is distributed between the part of the O-ring that enters the hole and the part that enters the groove. Therefore, the disc brake device can reduce the load on the O-ring that is subjected to contact with the outer surface of the rotating member by the portion of the O-ring that enters the hole, and consequently, can prevent the O-ring from wearing out or being damaged.

[0105] In the above-described disc brake device, for example, in the radial direction perpendicular to the central axis, the width of the groove is greater than the distance between the side surface and the outer surface. Therefore, for example, a portion of the O-ring, when pressed by pressure, enters the hole. However, because the width of the groove is greater than the distance between the side surface and the outer surface, the O-ring is more likely to enter the groove than the hole. As a result, the stress on the portion of the O-ring that enters the hole is reduced compared to the case where the distance between the side surface and the outer surface is greater than the width of the groove. Therefore, the disc brake device can reduce the load on the portion of the O-ring that enters the hole by contact with the outer surface of the rotating member, and consequently, can suppress wear or damage to the O-ring.

[0106] In the above-described disc brake device, for example, the groove is provided at the end of the side surface on the radially outer side perpendicular to the central axis, and is located between the inner circumferential surface and the side surface. Therefore, for example, the groove is spaced as far away from the hole as possible on the side surface. As a result, the disc brake device can better distribute the stress on the O-ring between the portion of the O-ring that enters the hole and the portion that enters the groove.

[0107] A disc brake device according to at least one embodiment described above includes, as an example, a caliper body having a hole extending along a central axis and a bore that communicates with the end of the hole in a first axial direction along the central axis and opens to the outside, an inner circumferential surface provided in the bore and facing the central axis, and a side surface provided in the bore and through which the hole opens; a rotating member having an outer circumferential surface extending through the hole and facing the inner circumferential surface, and a screw thread located in the bore, and rotatable around the central axis; a linear member located in the bore and attached to the screw thread so as to move in the first axial direction or in a second axial direction opposite to the first axial direction in response to the rotation of the screw thread around the central axis; and a member fitted into the bore so as to be movable along the central axis and the first axial The caliper comprises a piston configured to be biased toward the brake pad by the linear motion member that moves in the direction, and also configured to be biased toward the brake pad by the pressure of the brake fluid in the bore; an O-ring that contacts the inner and outer circumferential surfaces and seals the space between the inner and outer circumferential surfaces; a bush having a cylindrical portion that extends through the hole and is located in the hole between the outer circumferential surface and the caliper body; a flange portion located in the bore and extending from the cylindrical portion toward the inner circumferential surface; the flange portion having a support surface that contacts the O-ring, an outer groove recessed from the support surface provided between the inner circumferential surface and the flange portion, and the distance between the inner circumferential surface and the support surface in the radial direction perpendicular to the central axis is greater than the thickness of the flange portion along the central axis. Therefore, as an example, when the pressure of the brake fluid in the bore increases, the pressure presses the O-ring against the support surface. When an O-ring is pressed, it elastically deforms not only in the gap between the support surface and the outer surface, but also to enter the outer groove. Because the width of the outer groove is set to be large, a larger portion of the O-ring enters the outer groove. As a result, the stress on the O-ring is distributed between the portion that enters the gap and the portion that enters the outer groove, compared to when there is no outer groove.Therefore, the disc brake device can reduce the load on the O-ring that is subjected to contact with the outer surface of the rotating member by the portion of the O-ring that enters the gap, and consequently, it can suppress wear or damage to the O-ring.

[0108] In the disc brake device described above, for example, the distance between the inner circumferential surface and the support surface in the radial direction is greater than the distance between the support surface and the outer circumferential surface. Therefore, for example, a portion of the O-ring, when pressed, enters the gap between the support surface and the outer circumferential surface. However, because the distance between the inner circumferential surface and the support surface is greater than the distance between the support surface and the outer circumferential surface, the O-ring is more likely to enter the outer groove than the gap. As a result, the stress on the portion of the O-ring that enters the gap is reduced compared to the case where the distance between the support surface and the outer circumferential surface is greater than the distance between the inner circumferential surface and the support surface. Therefore, the disc brake device can reduce the load on the portion of the O-ring that enters the gap by contacting the outer circumferential surface of the rotating member, and consequently, can suppress wear or damage to the O-ring.

[0109] Although embodiments of the present invention have been illustrated above, these embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and changes can be made without departing from the spirit of the invention. Furthermore, the configurations and shapes of each embodiment and modification can be partially replaced. [Explanation of symbols]

[0110] 10...Disc brake device, 22...Brake pad, 32...Caliper body, 33...Piston, 36...O-ring, 45...Bore, 46...Through hole (hole), 51c...Inner circumferential surface, 51d...Side surface, 57...Groove, 61...Rotating member, 62...Linear motion member, 66a...Outer circumferential surface, 67b...Male screw (thread), 200...Bush, 201...Cylinder part, 202...Flange part, 202a...Support surface, Ax...Central axis, Do...Outward direction (first axial direction), Di...Inward direction (second axial direction).

Claims

1. A caliper body is provided with a hole extending along a central axis, a bore that communicates with the end of the hole in a first axial direction along the central axis and opens to the outside, an inner circumferential surface provided on the bore and facing the central axis, and a side surface provided on the bore and through which the hole opens, A rotating member having an outer surface extending through the hole and facing the inner surface, and screw threads located in the bore, and rotatable around the central axis, A linear motion member is located in the bore and attached to the threads so as to move in the first axial direction or in a second axial direction opposite to the first axial direction in response to the rotation of the threads around the central axis of the threads, A piston is fitted into the bore so as to be movable along the central axis, and is configured to be biased toward the brake pad by the linear motion member that moves in the first axial direction, and is also configured to be biased toward the brake pad by the pressure of the brake fluid in the bore, An O-ring that contacts the inner circumferential surface, the side surface, and the outer circumferential surface, and seals the space between the inner circumferential surface and the outer circumferential surface, It is equipped with, A groove spaced apart from the hole is provided on the aforementioned side surface. Disc brake system.

2. In the radial direction perpendicular to the central axis, the width of the groove is greater than the distance between the side surface and the outer circumferential surface. A disc brake device according to claim 1.

3. The groove is provided at the end of the side surface on the radially outer side perpendicular to the central axis, and is located between the inner circumferential surface and the side surface. A disc brake device according to claim 1.

4. A caliper body is provided with a hole extending along a central axis, a bore that communicates with the end of the hole in a first axial direction along the central axis and opens to the outside, an inner circumferential surface provided on the bore and facing the central axis, and a side surface provided on the bore and through which the hole opens, A rotating member having an outer surface extending through the hole and facing the inner surface, and screw threads located in the bore, and rotatable around the central axis, A linear motion member is located in the bore and attached to the threads so as to move in the first axial direction or in a second axial direction opposite to the first axial direction in response to the rotation of the threads around the central axis of the threads, A piston is fitted into the bore so as to be movable along the central axis, and is configured to be biased toward the brake pad by the linear motion member that moves in the first axial direction, and is also configured to be biased toward the brake pad by the pressure of the brake fluid in the bore, An O-ring that contacts the inner circumferential surface and the outer circumferential surface and seals the space between the inner circumferential surface and the outer circumferential surface, A bush having a cylindrical portion extending through the hole and located between the outer circumferential surface and the caliper body in the hole, a flange portion located in the bore and extending from the cylindrical portion toward the inner circumferential surface, It is equipped with, The flange portion has a support surface that contacts the O-ring, An outer groove recessed from the support surface is provided between the inner circumferential surface and the flange portion. The distance between the inner circumferential surface and the support surface in the radial direction perpendicular to the central axis is greater than the thickness of the flange along the central axis. Disc brake system.

5. In the radial direction, the distance between the inner circumferential surface and the support surface is greater than the distance between the support surface and the outer circumferential surface. The disc brake device according to claim 4.

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