JP2024076653A - Braking device - Google Patents

Abstract

[Problem] To provide a braking device capable of suppressing dust generated by wear of a male screw and a female screw from interfering with the operation of a rotating member and a linearly moving member. [Solution] A braking device according to an embodiment includes, as an example, a rotating member provided with one of a male screw located inside a cylinder and a female screw meshing with the male screw and rotatable around a rotation axis, a linearly moving member provided with the other of the male screw and the female screw and moving in a direction along the rotation axis when the rotating member rotates, and a piston fitted into the cylinder so as to be movable along the rotation axis, the rotating member having an inclined surface inclined with respect to the rotation axis so as to send a fluid inside the cylinder toward the linearly moving member by rotating in at least one of the first rotation direction and the second rotation direction. [Selected Figure] Figure 2

Description

An embodiment of the present invention relates to a braking device.

Conventionally, braking devices are known that convert the rotation of a rotating member driven by a motor into linear motion of a linear motion member, and the linear motion member presses brake pads against a brake rotor via a piston.

For example, a groove is provided on the thread of the rotating member. The groove supplies lubricating oil to the male and female threads that mesh with each other, reducing friction between the male and female threads. In this embodiment, it is also expected that the lubricating oil flowing through the groove will expel dust generated by wear between the male and female threads (Patent Document 1).

DE 102018005598 A1

However, in conventional configurations, the provision of grooves reduces the area of the male and female threads that receives the load. This increases the surface pressure, making the male and female threads more susceptible to wear. Dust generated by wear can interfere with the operation of the rotating and linear moving members.

The present invention has been made in consideration of the above, and provides a braking device that can prevent dust generated by wear between the male and female threads from interfering with the operation of the rotating member and the linear member.

As an example, a braking device according to an embodiment of the present invention includes a body having a cylinder, a rotating member having one of a male screw located inside the cylinder and a female screw engaging with the male screw and rotatable around a rotation axis, a linear motion member having the other of the male screw and the female screw, which moves in a first direction along the rotation axis when the rotating member rotates in a first rotation direction around the rotation axis and moves in a second direction opposite to the first direction when the rotating member rotates in a second rotation direction opposite to the first rotation direction, and a piston that is fitted into the cylinder so as to be movable along the rotation axis, is pushed in the first direction by the linear motion member moving in the first direction, and presses the braking member against the brake rotor by moving in the first direction, and the rotating member has a slope inclined with respect to the rotation axis so as to send fluid inside the cylinder toward the linear motion member by rotating in at least one of the first rotation direction and the second rotation direction. Therefore, as an example, the braking device generates a fluid flow inside the cylinder when the linear motion member moves in the first direction or the second direction, and can discharge dust generated by wear of the male and female threads from the male and female threads. This allows the braking device to prevent dust from interfering with the operation of the rotating member and the linear motion member.

FIG. 1 is a cross-sectional view that illustrates a braking device according to a first embodiment. FIG. 2 is a cross-sectional view that shows a schematic view of a part of the braking device of the first embodiment. FIG. 3 is a front view that illustrates the rotating member of the first embodiment. FIG. 4 is a cross-sectional view that shows a schematic view of a part of the braking device when the rotating member of the first embodiment rotates in the reverse direction. FIG. 5 is a cross-sectional view that shows a schematic view of a part of a braking device according to a second embodiment. FIG. 6 is a cross-sectional view that shows a schematic view of a part of a braking device according to a third embodiment.

First Embodiment
The first embodiment will be described below with reference to FIGS. 1 to 4. In this specification, components according to the embodiment and descriptions of the components may be described in a number of ways. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may be identified by names different from those in this specification. The components may also be described by expressions different from those in this specification.

Figure 1 is a cross-sectional view that shows a schematic diagram of a braking device 10 according to a first embodiment. As shown in Figure 1, the braking device 10 has a caliper 11, a brake rotor 12, a rotary-to-linear motion conversion mechanism 13, a rotation transmission mechanism 14, a motor 15, and an ECU (electronic control unit) 16. The rotary-to-linear motion conversion mechanism 13 is built into the caliper 11, and is operatively connected to the rotation transmission mechanism 14 that is attached to the caliper 11.

The braking device 10 can operate as a hydraulic brake and can also operate as an electric brake. For example, the caliper 11 constitutes a hydraulic brake, and the caliper 11, the rotary-to-linear conversion mechanism 13, the rotation transmission mechanism 14, and the motor 15 constitute an electric brake. Note that the braking device 10 may simply be an electric brake.

The electric brake is a so-called electric parking brake (EPB). That is, the braking device 10 is configured so that the braking state by the electric brake function is maintained when the vehicle is parked. The electric brake may be activated while driving or when the vehicle is temporarily stopped.

The caliper 11 has a body 21, a piston 22, two brake pads 23, and a piston seal 24. The brake pads 23 are an example of a braking member. A cylinder 25 is provided in the body 21.

The cylinder 25 is a generally cylindrical recess extending along a central axis Ax. The central axis Ax is an example of a rotation axis. In this embodiment, the central axis Ax is the center of the cylinder 25. Note that the rotation axis is not limited to the central axis Ax of the cylinder 25.

Hereinafter, the direction along the central axis Ax will be referred to as the axial direction, the direction perpendicular to the central axis Ax as the radial direction, and the direction around the central axis Ax as the circumferential direction. Furthermore, one of the axial directions (the left direction in FIG. 1) will be referred to as the lock direction D1, and the direction opposite to the lock direction D1 (the right direction in FIG. 1) as the release direction D2. The lock direction D1 is an example of the first direction. The release direction D2 is an example of the second direction.

The cylinder 25 is open in the locking direction D1. The body 21 has an inner circumferential surface 25a and a bottom surface 25b of the cylinder 25. The inner circumferential surface 25a and the bottom surface 25b are the inner surfaces of the body 21 that form (define, partition) the cylinder 25. The inner circumferential surface 25a is a substantially cylindrical curved surface that faces radially inward. The bottom surface 25b is connected to the end of the inner circumferential surface 25a in the release direction D2. The bottom surface 25b is formed substantially flat and faces the locking direction D1.

The piston 22 is fitted into the cylinder 25 so as to be capable of reciprocating along the central axis Ax. A hydraulic chamber R is provided within the cylinder 25. As the hydraulic pressure in the hydraulic chamber R increases, the piston 22 moves in the locking direction D1 and presses the back plate 27 of the brake pad 23, thereby pressing the lining 28 of the brake pad 23 against the brake rotor 12. This brakes the vehicle wheels that rotate integrally with the brake rotor 12, and a braking state is achieved by hydraulic braking.

The piston 22 has an outer peripheral surface 22a and an end surface 22b. The outer peripheral surface 22a is a generally cylindrical curved surface that faces radially outward. The outer peripheral surface 22a faces the inner peripheral surface 25a of the cylinder 25. The end surface 22b is the end surface of the piston 22 in the locking direction D1.

The piston 22 is provided with a recess 22c. The recess 22c is a generally cylindrical depression that is open in the release direction D2. That is, the recess 22c is provided on the opposite side of the outer circumferential surface 22a and the end surface 22b. The recess 22c forms a part of the hydraulic chamber R.

A small gap (clearance) is provided between the outer peripheral surface 22a of the piston 22 and the inner peripheral surface 25a of the cylinder 25. The outer peripheral surface 22a slides against the inner peripheral surface 25a while being lubricated by the brake fluid present in the gap.

The piston seal 24 is interposed between the outer peripheral surface 22a of the piston 22 and the inner peripheral surface 25a of the cylinder 25, and seals the gap between the outer peripheral surface 22a and the inner peripheral surface 25a. In this way, the piston seal 24 prevents brake fluid from leaking from the hydraulic chamber R through the gap.

The piston seal 24 is attached to the inner circumferential surface 25a of the cylinder 25 and is restricted from moving relative to the body 21. The piston seal 24 may also be attached to the outer circumferential surface 22a of the piston 22.

The piston seal 24 has a retract function that retracts the piston 22 in the release direction D2 toward the hydraulic chamber R with elastic force as the hydraulic pressure in the hydraulic chamber R drops, separating the end face 22b of the piston 22 from the brake pad 23. In other words, when the pressure of the piston 22 against the back plate 27 is released as the hydraulic pressure in the hydraulic chamber R drops, the piston 22 releases the pressure of the lining 28 against the brake rotor 12. This results in a brake release state due to the hydraulic brake. In this way, the caliper 11 can operate as a hydraulic brake.

The rotary-linear motion conversion mechanism 13 is provided inside the caliper 11. The rotary-linear motion conversion mechanism 13 has a rotating member 31, a linear motion member 32, and a thrust bearing 33. The rotating member 31 may also be referred to as a bolt. The linear motion member 32 may also be referred to as a nut.

The rotating member 31 is supported by the body 21 so as to be rotatable about the central axis Ax. The linear motion member 32 is attached to the rotating member 31 so as to be linearly movable in the axial direction in response to the rotation of the rotating member 31.

The rotation transmission mechanism 14 is, for example, a reducer having multiple rotating elements such as gears. The rotation transmission mechanism 14 transmits the rotation of the output shaft of the motor 15 to the rotating member 31. The rotating member 31 rotates around the central axis Ax due to the torque input from the rotation transmission mechanism 14.

Figure 2 is a cross-sectional view that shows a schematic view of a portion of the braking device 10 of the first embodiment. As shown in Figure 2, the rotating member 31 has a flange 41, a coupling portion 42, a shaft 43, and a number of fins 44. The fins 44 are an example of a protrusion.

The flange 41 is formed in a generally disk-like shape that is generally perpendicular to the central axis Ax. The flange 41 is located between the coupling portion 42 and the shaft 43. The flange 41 has two side surfaces 41a, 41b and an outer peripheral surface 41c.

The side surface 41a is formed substantially flat and faces the locking direction D1. The side surface 41a faces the bottom surface 25b of the cylinder 25 via a gap. The side surface 41b is located on the opposite side of the side surface 41a. The side surface 41b is formed substantially flat and faces the release direction D2. The outer peripheral surface 41c is the end surface of the flange 41 on the radially outer side. The outer peripheral surface 41c is formed substantially cylindrical and faces the radially outward. The outer peripheral surface 41c faces the inner peripheral surface 25a of the cylinder 25 via a gap.

Each of the coupling portion 42 and the shaft 43 is formed in a generally cylindrical shape extending along the central axis Ax. In this embodiment, the central axis Ax is also the central axis of the flange 41, the coupling portion 42, and the shaft 43.

The coupling portion 42 extends from the side surface 41b of the flange 41 in the release direction D2. The coupling portion 42 is supported by the body 21 so as to be rotatable around the central axis Ax, for example, and is coupled to the output shaft of the rotation transmission mechanism 14.

The shaft 43 extends from the side surface 41a of the flange 41 in the locking direction D1. The shaft 43 has an outer peripheral surface 43a. The outer peripheral surface 43a is formed in a substantially cylindrical shape and faces radially outward. The outer peripheral surface 43a faces the inner peripheral surface 25a of the cylinder 25 via a gap. A male thread 45 is provided on the outer peripheral surface 43a.

The flange 41 protrudes radially outward from the end of the coupling portion 42 in the locking direction D1. In other words, the flange 41 protrudes radially outward from the end of the shaft 43 in the release direction D2.

The thrust bearing 33 is disposed between the side surface 41b of the flange 41 and the bottom surface 25b of the cylinder 25. The bottom surface 25b supports the rotating member 31 in the axial direction via the thrust bearing 33.

The rotating member 31 is located inside the hydraulic chamber R of the cylinder 25. Therefore, the male thread 45 is also located inside the hydraulic chamber R of the cylinder 25. The shaft 43 may extend to the outside of the cylinder 25.

The multiple fins 44 protrude from the side surface 41a of the flange 41 in the locking direction D1. The fins 44 can rotate together with the flange 41 around the central axis Ax. The length Lf of the fins 44 in the axial direction is at least twice the pitch Lp of the male thread 45. Note that the length of the fins 44 is not limited to this example.

Each of the multiple fins 44 has two inclined surfaces 44a, 44b. In other words, the inclined surfaces 44a, 44b are provided on the fins 44, and the rotating member 31 has multiple inclined surfaces 44a and multiple inclined surfaces 44b. The multiple inclined surfaces 44a, 44b are an example of an inclined surface and an example of multiple sending surfaces. Note that the rotating member 31 may have a single inclined surface.

Each of the inclined surfaces 44a and 44b is inclined with respect to the central axis Ax and the side surface 41a. That is, neither of the inclined surfaces 44a and 44b is perpendicular to either the central axis Ax or the side surface 41a, and neither of the inclined surfaces 44a and 44b is parallel to either the central axis Ax or the side surface 41a.

Figure 3 is a front view that shows a schematic of the rotating member 31 of the first embodiment. As shown in Figure 3, hereinafter, one of the circumferential directions (clockwise direction in Figure 3) is referred to as the forward rotation direction Dn, and the opposite direction to the forward rotation direction Dn (counterclockwise direction in Figure 3) is referred to as the reverse rotation direction Dr. The forward rotation direction Dn is an example of a first rotation direction. The reverse direction Dr is an example of a second rotation direction.

The inclined surface 44a faces in an oblique direction having a component in the normal rotation direction Dn. In other words, the inclined surface 44a is inclined with respect to the central axis Ax so as to approach the side surface 41a as it moves in the normal rotation direction Dn.

The slope 44b is located on the opposite side of the slope 44a. The slope 44b faces in an oblique direction having a component in the reverse direction Dr. In other words, the slope 44b is inclined with respect to the central axis Ax so as to approach the side surface 41a as it moves in the reverse direction Dr.

As shown in FIG. 2, in this embodiment, the inclined surface 44a is a curved surface recessed approximately in the reverse rotation direction Dr. The inclined surface 44b is a curved surface recessed approximately in the forward rotation direction Dn. The inclined surfaces 44a and 44b may be flat surfaces.

As shown in FIG. 3, the multiple fins 44 extend radially from the central axis Ax. Therefore, the inclined surfaces 44a, 44b of the multiple fins 44 also extend radially from the central axis Ax. In other words, the multiple fins 44 are arranged at intervals in the circumferential direction.

The end 44c of the fin 44 on the inside in the radial direction is connected to, for example, the shaft 43. The end 44d of the fin 44 on the outside in the radial direction is located, for example, near the outer circumferential surface 41c of the flange 41.

The linear motion member 32 has a cylindrical portion 51 and two protrusions 52. The cylindrical portion 51 is formed in a generally cylindrical shape that extends in the axial direction and surrounds the central axis Ax. The cylindrical portion 51 has an inner peripheral surface 51a and an outer peripheral surface 51b.

The inner peripheral surface 51a is a generally cylindrical curved surface that extends in the axial direction and faces inward in the radial direction. A female thread 53 is provided on the inner peripheral surface 51a. The female thread 53 meshes with the male thread 45 of the rotating member 31. In this way, the linear motion member 32 is attached to the shaft 43. The side surface 41a of the flange 41 faces the linear motion member 32.

The outer peripheral surface 51b is located on the opposite side of the inner peripheral surface 51a. The outer peripheral surface 51b is a generally cylindrical curved surface that extends in the axial direction and faces radially outward. The diameter of the outer peripheral surface 51b is shorter than the diameter of the flange 41. Therefore, the outer peripheral surface 41c of the flange 41 and the end 44d of the fin 44 are each farther away from the central axis Ax than the outer peripheral surface 51b of the cylindrical portion 51.

The protrusions 52 protrude radially outward from the outer circumferential surface 51b. The two protrusions 52 protrude in opposite directions from the outer circumferential surface 51b (upward and downward in each drawing). Note that the number and directions of the protrusions 52 are not limited to this example.

A part of the rotary-linear conversion mechanism 13 is housed inside the recess 22c of the piston 22. Specifically, a part of the shaft 43 of the rotating member 31 is located inside the recess 22c. In addition, the linear motion member 32 is provided so as to be movable in the axial direction inside the recess 22c.

The piston 22 further has an inner peripheral surface 22d and a bottom surface 22e of the recess 22c. The inner peripheral surface 22d and the bottom surface 22e are the inner surfaces of the piston 22 that form the recess 22c. The inner peripheral surface 22d is formed in a generally cylindrical shape that faces inward in the radial direction of the central axis Ax. The bottom surface 22e is connected to the end of the inner peripheral surface 22d in the locking direction D1. The bottom surface 22e faces the release direction D2.

Two guide grooves 22f are provided on the inner circumferential surface 22d of the piston 22. The two guide grooves 22f are recessed radially outward from the inner circumferential surface 22d in opposite directions (upward and downward in each figure) and extend in the axial direction.

The protrusion 52 of the linear motion member 32 is accommodated in the guide groove 22f so as to be movable along the guide groove 22f. For example, the side surface of the guide groove 22f facing in the circumferential direction abuts against the side surface of the protrusion 52 facing in the circumferential direction, thereby restricting the rotation of the linear motion member 32 around the central axis Ax.

As described above, the male thread 45 of the rotating member 31 and the female thread 53 of the linear motion member 32 mesh with each other, and the rotation of the protrusion 52 of the linear motion member 32 is restricted by the guide groove 22f of the piston 22. This allows the linear motion member 32 to move linearly in the axial direction in response to the rotation of the rotating member 31. In other words, the linear motion member 32 can move approximately parallel to the axial direction.

The motor 15 shown in FIG. 1 is driven by drive power based on a control signal. The motor 15 rotates the output shaft of the motor 15, thereby driving the rotating member 31 to rotate about the central axis Ax via the rotation transmission mechanism 14.

For example, when the output shaft of the motor 15 rotates in one direction, the rotating member 31 rotates in the forward direction Dn. When the rotating member 31 rotates in the forward direction Dn, the linear moving member 32 moves straight (in a locking direction D1).

The linear motion member 32, which moves in the locking direction D1, pushes the piston 22 in the locking direction D1. The piston 22, pushed by the linear motion member 32, moves in the locking direction D1, and presses the lining 28 against the brake rotor 12 via the back plate 27. This results in a braking state due to the electric brake function, in which the vehicle wheels, which rotate integrally with the brake rotor 12, are braked.

When the output shaft of the motor 15 rotates in the reverse direction, the rotating member 31 rotates in the reverse direction Dr. When the rotating member 31 rotates in the reverse direction Dr, the linear motion member 32 moves straight (moves) in the release direction D2, moving away from the piston 22. The movement of the linear motion member 32 in the release direction D2 reduces the pressing force of the piston 22 against the back plate 27, and the piston 22 releases the pressing of the lining 28 against the brake rotor 12. This results in a released state (non-braked state) of the braking by the electric brake function. In this way, the caliper 11, the rotary-linear motion conversion mechanism 13, the rotation transmission mechanism 14, and the motor 15 can operate as an electric brake.

In this embodiment, the ECU 16 controls the motor 15 of the braking device 10. The ECU 16 may also be referred to as an electronic control device. The ECU 16 may be configured in part by hardware such as a CPU or controller that executes software, or may be configured entirely by hardware. Note that the motor 15 is not limited to being controlled by the ECU 16, and may be controlled, for example, by a dedicated controller of the braking device 10.

For example, when the ECU 16 receives an instruction signal to transition to a braking state from an operating switch (SW) for the electric brake function, the ECU 16 controls the motor 15 so that the rotating member 31 rotates in the forward direction Dn. On the other hand, when the ECU 16 receives an instruction signal to release the braking state from the operating switch, the ECU 16 controls the motor 15 so that the rotating member 31 rotates in the reverse direction Dr.

As shown by the arrow in FIG. 2, when the rotating member 31 rotates in the forward direction Dn, the inclined surface 44a of the fin 44 sends the brake fluid in the hydraulic chamber R of the cylinder 25 in the locking direction D1. The brake fluid in the hydraulic chamber R is an example of a fluid inside the cylinder.

Figure 4 is a cross-sectional view that shows a schematic view of a part of the braking device 10 when the rotating member 31 of the first embodiment rotates in the reverse direction Dr. When the rotating member 31 rotates in the reverse direction Dr, the inclined surface 44b sends the brake fluid in the hydraulic chamber R in the locking direction D1.

The linear motion member 32 is disposed at a position spaced apart from the fin 44 in the locking direction D1. Therefore, the inclined surfaces 44a, 44b rotate in the forward direction Dn or the reverse direction Dr in conjunction with the rotation of the rotating member 31, thereby sending brake fluid toward the linear motion member 32. In other words, the multiple fins 44 form an impeller Im that sends brake fluid toward the linear motion member 32 in conjunction with the rotation about the central axis Ax. Note that the inclined surfaces 44a, 44b may simultaneously send a flow of brake fluid toward the linear motion member 32 in another direction, provided that they cause a flow of brake fluid toward the linear motion member 32.

As shown in FIG. 3, the boundary 44e between the inclined surface 44a and the side surface 41a extends so as to bend in the forward rotation direction Dn as it moves radially outward. The boundary 44f between the inclined surface 44b and the side surface 41a extends so as to bend in the reverse rotation direction Dr as it moves radially outward. This allows the inclined surfaces 44a and 44b to efficiently deliver brake fluid. The boundaries 44e and 44f may also extend linearly.

As shown in FIG. 2, when the rotating member 31 rotates in the forward direction Dn, convection occurs in the brake fluid through the gap between the outer circumferential surface 51b of the cylindrical portion 51 and the inner circumferential surface 22d of the piston 22, or through the guide groove 22f. The flow of brake fluid flows into the inside of the cylindrical portion 51, for example, through the gap between the cylindrical portion 51 and the bottom surface 22e of the recess 22c.

The flow of brake fluid passes through the portion where the male thread 45 and female thread 53 mesh inside the cylindrical portion 51 (hereinafter referred to as the meshing portion Pe) and flows toward the flange 41. As a result, even if dust is generated due to wear between the male thread 45 and female thread 53, the flow of brake fluid expels the dust from the meshing portion Pe.

When the rotating member 31 rotates in the forward direction Dn, the linear member 32 moves in the locking direction D1. Meanwhile, inside the cylindrical portion 51, the brake fluid flows in the release direction D2. This increases the relative speed of the brake fluid with respect to the female thread 53 of the linear member 32, and dust is easily discharged from the meshing portion Pe.

As shown in FIG. 4, when the rotating member 31 rotates in the reverse direction Dr, convection occurs in the brake fluid through the inside of the cylindrical portion 51. The flow of brake fluid passes through the meshing portion Pe inside the cylindrical portion 51 and flows toward the bottom surface 22e of the recess 22c. As a result, the flow of brake fluid expels dust from the meshing portion Pe.

When the rotating member 31 rotates in the reverse direction Dr, the linear member 32 moves in the release direction D2. Meanwhile, inside the cylindrical portion 51, the brake fluid flows in the lock direction D1. This increases the relative speed of the brake fluid with respect to the female thread 53 of the linear member 32, and dust is easily discharged from the meshing portion Pe.

As shown by the two-dot chain line in FIG. 4, when the linear member 32 moves to the maximum in the release direction D2, it abuts against the fin 44. As a result, the fin 44 restricts the linear member 32 from moving further in the release direction D2. The ECU 16 can detect that the linear member 32 has moved to the maximum in the release direction D2, for example, based on an increase in the current value of the motor 15 when the linear member 32 abuts against the fin 44.

The contact area between the linear motion member 32 and the fins 44 is smaller than the contact area between the linear motion member 32 and the side surface 41a when the linear motion member 32 abuts against the side surface 41a of the flange 41, for example. Therefore, by providing the fins 44, the rotary-linear motion conversion mechanism 13 can reduce the load on the motor 15 when the rotating member 31 rotates in the forward direction Dn and the linear motion member 32 moves in the locking direction D1.

The braking device 10 further includes a plurality of magnets 61, 62, and 63. The magnets 61, 62, and 63 are, for example, permanent magnets. Note that the magnets 61, 62, and 63 are not limited to this example and may be other magnets.

The magnet 61 is provided on the inner peripheral surface 25a of the cylinder 25. For example, the magnet 61 is farther away from the linear motion member 32 in the axial direction than the fin 44 is. Therefore, when the linear motion member 32 abuts against the fin 44, the magnet 61 is farther away from the linear motion member 32 in the axial direction.

The magnet 62 is provided on the inner circumferential surface 22d or the guide groove 22f of the piston 22. The magnets 61 and 62 are located below the central axis Ax. Note that the positions of the magnets 61 and 62 are not limited to this example. The magnet 63 is provided on the bottom surface 22e of the piston 22. The magnet 63 is, for example, positioned on the central axis Ax.

The rotating member 31 and the linear motion member 32 are made of, for example, metal. Therefore, the dust generated by wear of the rotating member 31 and the linear motion member 32 contains metal. The dust floating in the hydraulic chamber R is attracted to the magnets 61, 62, and 63.

The linear motion member 32 abuts against the bottom surface 22e of the piston 22, thereby restricting the piston 22 from moving further in the release direction D2. When the piston 22 moves to its maximum extent in the release direction D2, the magnet 61 is separated from the piston 22. Therefore, the magnet 61 can prevent dust attracted to the magnet 61 from interfering with the sliding of the piston 22.

The magnet 62 is spaced apart from the cylindrical portion 51 in the radial direction. Furthermore, the magnet 62 is spaced apart from the protrusion 52 in the axial direction. Therefore, the magnet 62 is spaced apart from the linear motion member 32, and dust attracted to the magnet 62 can be prevented from interfering with the movement of the linear motion member 32.

The magnet 63 is disposed at a position on the bottom surface 22e facing the shaft 43. Therefore, in the radial direction, the magnet 63 is located inside the linear motion member 32. When the linear motion member 32 abuts against the bottom surface 22e of the piston 22, the magnet 63 is separated from the linear motion member 32. Therefore, the magnet 63 can prevent dust attracted to the magnet 63 from interfering with the movement of the linear motion member 32.

In the braking device 10 according to the first embodiment described above, the rotating member 31 has inclined surfaces 44a and 44b. The inclined surfaces 44a and 44b are inclined with respect to the rotating member 31 so as to send the brake fluid inside the cylinder 25 toward the linear moving member 32 by rotating in at least one of the forward rotation direction Dn and the reverse rotation direction Dr. In other words, the braking device 10 can stir the brake fluid by the rotating member 31 and generate convection in the brake fluid without adding any other parts different from the rotating member 31. As a result, the braking device 10 can generate a flow of brake fluid inside the cylinder 25 when the linear moving member 32 moves in the lock direction D1 or the release direction D2, and can discharge dust generated by wear of the male thread 45 and the female thread 53 from the male thread 45 and the female thread 53. The braking device 10 having the slopes 44a and 44b prevents the load-bearing area of the male thread 45 and female thread 53 from decreasing, compared to a configuration in which grooves for discharging dust are provided on the male thread 45 or female thread 53, and thus reduces wear on the male thread 45 and female thread 53 due to increased surface pressure. As a result, the braking device 10 can prevent dust from interfering with the operation of the rotating member 31 and the linear member 32, and can perform stable braking.

The rotating member 31 has a shaft 43, a flange 41, and a fin 44. The flange 41 protrudes from the end of the shaft 43 in the release direction D2 in a direction perpendicular to the central axis Ax. The fin 44 protrudes from the flange 41 in the locking direction D1. The inclined surfaces 44a and 44b are provided on the fin 44. The inclined surfaces 44a and 44b provided on the fin 44 can efficiently send the brake fluid inside the cylinder 25 when the rotating member 31 rotates. Furthermore, when the linear member 32 moves to the maximum in the release direction D2, it can abut against the fin 44 instead of the flange 41. By the linear member 32 abutting against the fin 44, the contact area between the linear member 32 and the rotating member 31 is smaller than, for example, when the linear member 32 abuts against the flat side surface 41a of the flange 41. As a result, the fin 44 can reduce friction between the rotating member 31 and the linear member 32 compared to when the linear member 32 abuts against the side surface 41a of the flange 41. This reduction in friction contributes to a reduction in the rotation torque of the rotating member 31 required to start moving the linear member 32, which has moved to the maximum in the release direction D2, in the locking direction D1. That is, the fin 44 can function as a rotation stopper that suppresses locking between the rotating member 31 and the linear member 32 (fastening between the male screw 45 and the female screw 53). Note that, instead of the above, a rotation stopper that suppresses locking between the rotating member 31 and the linear member 32 can also be used that abuts the surface of the fin 44 facing forward in the reverse direction Dr (fin stopper surface, not shown) against a surface protruding from the end face of the linear member 32 on the release direction D2 side (rotating member stopper surface, not shown).

By rotating in the reverse direction Dr, the inclined surface 44b sends brake fluid inside the cylinder 25 toward the linear motion member 32. That is, the inclined surface 44b sends brake fluid toward the linear motion member 32 approaching the inclined surface 44b. This increases the relative speed of the brake fluid with respect to the linear motion member 32, allowing the brake fluid to efficiently expel dust from the male thread 45 and the female thread 53.

The multiple inclined surfaces 44a, 44b extend radially from the central axis Ax. Each of the multiple inclined surfaces 44a, 44b rotates in at least one of the forward direction Dn and the reverse direction Dr to send brake fluid inside the cylinder 25 to the linear motion member 32. This allows the braking device 10 to efficiently send brake fluid. Furthermore, the multiple inclined surfaces 44a, 44b can efficiently agitate the brake fluid inside the cylinder 25 and expel dust from the male thread 45 and the female thread 53.

In the first embodiment, the fin 44 has a slope 44a and a slope 44b. However, the fin 44 may have, for example, only the slope 44b. In this case, the fin 44 does not need to send brake fluid toward the linear motion member 32 when rotating in the forward rotation direction Dn. Similarly, the fin 44 may have only the slope 44a.

Second Embodiment
The second embodiment will be described below with reference to Fig. 5. In the following description of the embodiments, components having the same functions as components already described are given the same reference numerals as the components already described, and further description may be omitted. In addition, components given the same reference numerals do not necessarily have all the same functions and properties, and may have different functions and properties according to each embodiment.

Figure 5 is a cross-sectional view that shows a schematic view of a portion of a braking device 10 according to a second embodiment. As shown in Figure 5, the rotating member 31 of the second embodiment has a plurality of fins 201 instead of the plurality of fins 44. The fins 201 are substantially the same as the fins 44, except as described below.

The fin 201 is spaced apart from the shaft 43. Therefore, the end 201a of the fin 201 on the radially inner side is spaced apart from the shaft 43. The end 201a is spaced apart from the central axis Ax more than the outer circumferential surface 51b of the cylindrical portion 51.

The rotating member 31 further has a protrusion 211. The protrusion 211 protrudes from the side surface 41a of the flange 41. The length of the protrusion 211 in the axial direction is less than twice the pitch Lp of the male thread 45.

As shown by the two-dot chain line in FIG. 5, when the linear member 32 moves to its maximum extent in the release direction D2, it abuts against the protrusion 211. As a result, the protrusion 211 restricts the linear member 32 from moving further in the release direction D2. As with the fin 44 in the first embodiment, the protrusion 211 can reduce the load on the motor 15 when the rotating member 31 rotates in the forward direction Dn and the linear member 32 moves in the lock direction D1.

When the linear motion member 32 moves to its maximum extent in the release direction D2 and abuts against the protrusion 211, the fin 201 is spaced radially outward from the linear motion member 32. The end 201a of the fin 201 faces the outer circumferential surface 51b of the cylindrical portion 51.

In the braking device 10 of the second embodiment described above, when the linear member 32 moves to the maximum in the release direction D2, the fin 201 is spaced radially outward from the linear member 32. This allows the braking device 10 to bring the position of the linear member 32 when it moves to the maximum in the release direction D2 closer to the flange 41 than when the fin 44 having the inclined surfaces 44a, 44b abuts against the linear member 32. Therefore, the braking device 10 can shorten the length of the shaft 43 while setting a sufficient stroke of the linear member 32. Furthermore, even if the braking device 10 has a separate protrusion 211 protruding from the flange 41, the protrusion 211 can be made smaller.

Third Embodiment
The third embodiment will be described below with reference to Fig. 6. Fig. 6 is a cross-sectional view that shows a schematic view of a part of a braking device 10 according to the third embodiment. As shown in Fig. 6, a rotating member 31 of the third embodiment has a plurality of concave surfaces 301 instead of a plurality of fins 44. Furthermore, the rotating member 31 of the third embodiment has a protrusion 211 similar to the second embodiment.

The concave surface 301 is recessed from the side surface 41a of the flange 41 in the release direction D2. Each of the multiple concave surfaces 301 has an introduction surface 301a and an inclined surface 301b. Each of the introduction surface 301a and the inclined surface 301b is inclined with respect to the central axis Ax.

The introduction surface 301a faces in an oblique direction having a component in the forward rotation direction Dn. In other words, the introduction surface 301a is inclined with respect to the central axis Ax so as to move away from the side surface 41a as it moves in the forward rotation direction Dn.

The inclined surface 301b extends between the end of the introduction surface 301a in the forward rotation direction Dn and the side surface 41a. The inclined surface 301b faces in an oblique direction having a component in the reverse rotation direction Dr. In other words, the inclined surface 301b is inclined with respect to the central axis Ax so as to approach the side surface 41a as it moves in the forward rotation direction Dn.

In this embodiment, the introduction surface 301a is a substantially flat surface. On the other hand, the inclined surface 301b is a curved surface that is recessed in the forward rotation direction Dn. Note that the introduction surface 301a may be a curved surface, and the inclined surface 301b may be a flat surface.

In the circumferential direction, the introduction surface 301a is longer than the inclined surface 301b. Therefore, the average inclination angle of the introduction surface 301a relative to the side surface 41a is smaller than the average inclination angle of the inclined surface 301b relative to the side surface 41a. Note that the lengths and angles of the introduction surface 301a and the inclined surface 301b are not limited to this example.

The multiple concave surfaces 301 extend radially from the central axis Ax. Therefore, the inclined surfaces 301b of the multiple concave surfaces 301 also extend radially from the central axis Ax. In other words, the multiple concave surfaces 301 are arranged at intervals in the circumferential direction.

When the rotating member 31 rotates in the reverse direction Dr, the brake fluid in the hydraulic chamber R flows into the inside of the concave surface 301. The brake fluid flows along the inlet surface 301a and is sent in the locking direction D1 by the inclined surface 301b.

The inclined surface 301b rotates in the reverse direction Dr in conjunction with the rotation of the rotating member 31, thereby sending brake fluid toward the linearly moving member 32. In this way, the flange 41 having multiple inclined surfaces 301b forms an impeller Im that sends brake fluid toward the linearly moving member 32 in conjunction with the rotation about the central axis Ax.

In the braking device 10 of the third embodiment described above, the flange 41 has a side surface 41a facing the linear motion member 32 and a concave surface 301 recessed from the side surface 41a. The inclined surface 301b is included in the concave surface 301. As a result, the braking device 10 can bring the position of the linear motion member 32 when it moves to the maximum in the release direction D2 closer to the flange 41 than when the fin 44 having the inclined surfaces 44a and 44b protrudes from the flange 41. Therefore, the braking device 10 can shorten the length of the shaft 43 while setting a sufficient stroke of the linear motion member 32. Furthermore, even if the braking device 10 has a separate protrusion 211 protruding from the flange 41, the protrusion 211 can be made smaller.

As an example, the braking device according to at least one of the embodiments described above includes a body provided with a cylinder, a rotating member provided with one of a male screw located inside the cylinder and a female screw engaging with the male screw and rotatable around a rotation axis, a linear motion member provided with the other of the male screw and the female screw, which moves in a first direction along the rotation axis when the rotating member rotates in a first rotation direction around the rotation axis and moves in a second direction opposite to the first direction when the rotating member rotates in a second rotation direction opposite to the first rotation direction, and a piston that is fitted into the cylinder so as to be movable along the rotation axis, is pushed in the first direction by the linear motion member moving in the first direction, and presses the braking member against the brake rotor by moving in the first direction, and the rotating member has a slope inclined with respect to the rotation axis so as to send fluid inside the cylinder toward the linear motion member by rotating in at least one of the first rotation direction and the second rotation direction. Therefore, as an example, the braking device can agitate the fluid with the rotating member and generate convection in the fluid without adding any other parts different from the rotating member. As a result, the braking device generates a flow of fluid inside the cylinder when the linear motion member moves in the first direction or the second direction, and can discharge dust generated by wear of the male and female threads from the male and female threads. A braking device with a slope can prevent the area that receives the load on the male and female threads from decreasing, compared to a configuration in which a groove for discharging dust is provided in the male or female thread, and can therefore reduce wear of the male and female threads due to increased surface pressure. As a result, the braking device can prevent dust from interfering with the operation of the rotating member and the linear motion member, and can perform stable braking.

In the braking device, as an example, the rotating member has a shaft extending along the rotation axis and provided with the male screw, a flange extending from an end of the shaft in the second direction in a direction intersecting the rotation axis, and a convex portion protruding from the flange in the first direction, and the inclined surface is provided on the convex portion. Thus, as an example, the inclined surface is provided on the convex portion, so that the fluid inside the cylinder can be efficiently sent when the rotating member rotates. Furthermore, when the linear moving member moves to the maximum in the second direction, it can abut on the convex portion instead of the flange. When the linear moving member abuts on the convex portion, the contact area between the linear moving member and the rotating member is smaller than, for example, when the linear moving member abuts on the flat surface of the flange. As a result, the convex portion can reduce friction between the rotating member and the linear moving member compared to when the linear moving member abuts on the flat surface of the flange. This reduction in friction contributes to a reduction in the rotational torque of the rotating member required to start moving the linear moving member, which has moved to the maximum in the second direction, in the first direction. In other words, the protrusion can function as a rotation stopper that prevents the rotation member and the linear motion member from locking (fastening the male and female threads).

In the above braking device, as an example, the rotating member has a shaft that extends along the rotation axis and is provided with the male thread, and a flange that protrudes from the end of the shaft in the second direction in a direction intersecting the rotation axis, and the flange has a side surface facing the linear motion member and a concave surface recessed from the side surface, and the slope is included in the concave surface. Therefore, as an example, the braking device can bring the position of the linear motion member when it moves to the maximum in the second direction closer to the flange than when a convex portion having a slope protrudes from the flange. Therefore, the braking device can shorten the length of the shaft while setting a sufficient stroke of the linear motion member. Furthermore, even if the braking device has a separate rotation stopper protruding from the flange, the rotation stopper can be made smaller.

In the above braking device, as an example, the inclined surface is inclined with respect to the rotation axis so as to send the fluid inside the cylinder toward the linear motion member by rotating in the second rotation direction. Thus, as an example, the inclined surface sends the fluid toward the linear motion member approaching the inclined surface. This increases the relative speed of the fluid with respect to the linear motion member, and the fluid can efficiently expel dust from the male and female threads.

In the above braking device, as an example, the inclined surface has a plurality of delivery surfaces extending radially from the rotation axis, and each of the plurality of delivery surfaces is inclined with respect to the rotation axis so as to deliver the fluid inside the cylinder toward the linear motion member by rotating in at least one of the first rotation direction and the second rotation direction. Therefore, as an example, the braking device can deliver the fluid efficiently. Furthermore, the plurality of delivery surfaces can efficiently agitate the fluid inside the cylinder and expel dust from the male and female threads.

In the above explanation, suppression is defined as, for example, preventing the occurrence of an event, action, or effect, or reducing the severity of an event, action, or effect. In the above explanation, restriction is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a specified range and preventing movement or rotation beyond the specified range.

Although the above describes the embodiments of the present invention, the above embodiments and variations are merely examples and are not intended to limit the scope of the invention. The above embodiments and variations can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. In addition, the configurations and shapes of each embodiment and each variation can be partially interchanged.

10... Brake device, 12... Brake rotor, 21... Body, 22... Piston, 23... Brake pad (braking member), 25... Cylinder, 31... Rotating member, 32... Linear member, 41... Flange, 41a... Side, 43... Shaft, 44, 201... Fins (convex portion), 44a, 44b... Inclined surface (inclined surface, sending surface), 45... Male thread, 53... Female thread, 301... Concave surface, 301b... Inclined surface (inclined surface, sending surface), Ax... Center axis (rotation axis), D1... Lock direction (first direction), D2... Release direction (second direction), Dn... Forward direction (first rotation direction), Dr... Reverse direction (second rotation direction).

Claims (5)

A body provided with a cylinder;
a rotating member provided with one of a male screw located inside the cylinder and a female screw meshing with the male screw, the rotating member being rotatable around a rotation axis;
a linear motion member provided with the other of the male thread and the female thread, the linear motion member moving in a first direction along the rotation axis when the rotating member rotates in a first rotation direction about the rotation axis, and moving in a second direction opposite to the first direction when the rotating member rotates in a second rotation direction opposite to the first rotation direction;
a piston that is fitted in the cylinder so as to be movable along the rotation shaft, is pushed in the first direction by the linear motion member that moves in the first direction, and presses a braking member against the brake rotor by moving in the first direction;
Equipped with
The rotating member has an inclined surface inclined with respect to the rotation axis so as to rotate in at least one of the first rotation direction and the second rotation direction to send the fluid inside the cylinder toward the linear moving member.
Braking device. the rotating member includes a shaft extending along the rotation axis and provided with the male thread, a flange protruding from an end of the shaft in the second direction in a direction intersecting the rotation axis, and a protrusion protruding from the flange in the first direction,
The inclined surface is provided on the convex portion.
2. The braking device of claim 1. the rotating member includes a shaft extending along the rotation axis and provided with the male thread, and a flange extending from an end of the shaft in the second direction in a direction intersecting the rotation axis,
The flange has a side surface facing the linear motion member and a concave surface recessed from the side surface,
The inclined surface is included in the concave surface.
2. The braking device of claim 1. The inclined surface is inclined with respect to the rotation axis so as to rotate in the second rotation direction to send the fluid inside the cylinder toward the linear motion member.
A braking device according to any one of claims 1 to 3. The ramp has a plurality of delivery surfaces extending radially relative to the axis of rotation;
Each of the plurality of delivery surfaces is inclined with respect to the rotation axis so as to deliver the fluid inside the cylinder toward the linearly moving member by rotating in at least one of the first rotation direction and the second rotation direction.
A braking device according to any one of claims 1 to 3.

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