JP2020034146A - Vehicular brake - Google Patents

Abstract

To obtain a vehicular brake with a novel configuration, for example, which can suppress deterioration in force of a linear motion member for pressing a pad against a disc rotor.SOLUTION: A vehicular brake is made of, for example, a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material of a linear motion member; has an inclined surface that is inclined to a central axis and can press a pressing part in a second direction opposite to a first direction with thermal contraction due to temperature drop; and comprises a positive thermal expansion part capable of pressing a pad in the first direction with a reaction force generated by the pressing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle brake.

  Conventionally, a hydraulic brake that brakes wheels by pressing a pad against a disk rotor via a piston by hydraulic pressure, and converts the rotation of a rotating member driven by a motor into a linear motion of a linear motion member, There is known a vehicle brake that can operate as an electric parking brake that presses a pad against a disk rotor via a piston through a piston (Patent Document 1). Such a vehicle brake operates as an electric parking brake, for example, after operating as a hydraulic brake to stop the vehicle.

JP 2009-250423 A

  In this type of vehicle brake, for example, even when the pad is thermally contracted due to a decrease in temperature while operating as an electric parking brake, it is preferable that the force of the linear motion member pressing the pad against the disk rotor does not decrease.

  Therefore, one of the objects of the present invention is to obtain a vehicle brake having a novel configuration capable of suppressing a decrease in the force of a linear motion member pressing a pad against a disk rotor.

  The vehicle brake according to the embodiment includes, for example, a motor, a body provided with a cylinder, and a material having a positive linear thermal expansion coefficient, is housed in the cylinder, and is configured to receive the cylinder by a pressure of brake fluid in the cylinder. A piston that moves in a first direction along the central axis of the pad to press the pad against the disk rotor, a rotating member that is driven to rotate by the motor, and a material having a positive linear thermal expansion coefficient, and has a pressing portion. A rotation / linear motion converting mechanism having a linear motion member capable of pressing the piston by the pressing portion so as to move in the first direction by the rotation of the rotary member and press the pad against the disk rotor; It is composed of a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material of the member, and is inclined with respect to the central axis to decrease with temperature. The pad has an inclined surface capable of pressing the pressing portion in a second direction opposite to the first direction by thermal contraction, and the pad is pressed by a reaction force generated by pressing the pressing portion in the second direction by the inclined surface. A positive thermal expansion portion that can be pressed in the first direction.

  According to the above configuration, for example, when the pad thermally contracts due to the temperature decrease, the positive thermal expansion section also thermally contracts due to the temperature decrease, and the inclined surface of the positive thermal expansion section pushes the pressing section in the second direction opposite to the first direction. Press As the inclined surface presses the pressing portion in the second direction, the positive thermal expansion portion presses the pad in the first direction by a reaction force generated at that time. Therefore, according to the above configuration, even when the temperature is lowered, it is possible to suppress a decrease in the force of the linear motion member pressing the pad against the disk rotor. Further, the force of the linear motion member pressing the pad against the disk rotor can be adjusted by the angle and shape of the inclined surface.

  Further, in the vehicle brake, for example, the positive thermal expansion portion slides on a first surface extending in a radial direction of the center axis in the second direction due to thermal contraction accompanying a temperature decrease. In a cross-section including the second surface disposed on the first direction side than the inclined surface and extending in the radial direction and including the positive thermal expansion portion including the central axis and extending in the radial direction of the central axis, An intersection point of a tangent line of the inclined surface at a contact portion with the pressing portion and a straight line overlapping the first surface and extending in the radial direction is located on the contact portion side with respect to the central axis.

  According to the above configuration, for example, when the positive thermal expansion section thermally contracts due to a temperature drop, the slope of the positive thermal expansion section can suitably press the pressing section in the second direction opposite to the first direction.

  In the vehicle brake, for example, the positive thermal expansion portion is separate from the piston, and is made of a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material of the piston. , Interposed between the piston and the pressing portion in the axial direction of the central axis.

  According to the above configuration, for example, it is easy to geometrically increase the thermal contraction of the positive thermal expansion portion. Therefore, according to the above configuration, it is easy to increase the force of the direct acting member that presses the pad against the disk rotor when the temperature drops.

  The vehicle brake according to the embodiment includes, for example, a motor, a body provided with a cylinder, and a material having a positive linear thermal expansion coefficient, is housed in the cylinder, and is configured to receive the cylinder by a pressure of brake fluid in the cylinder. A piston that can move in a first direction along the central axis of the disk to press the pad against the disk rotor, a rotating member that is driven to rotate by the motor, and a material having a positive linear thermal expansion coefficient, and has a pressing portion. A rotation / linear motion converting mechanism having a linear motion member capable of being moved in the first direction by the rotation of the rotation member and pressing the piston by the pressing portion so as to press the pad against the disk rotor; And a negative thermal expansion member interposed between the piston and the pressing portion in the axial direction of the central axis. .

  According to the above configuration, for example, when the pad thermally contracts due to the temperature drop, the negative thermal expansion member thermally expands due to the temperature drop, and presses the piston and thus the pad against the disk rotor. Therefore, according to the above configuration, even when the temperature is lowered, it is possible to suppress a decrease in the force of the linear motion member pressing the pad against the disk rotor. Further, since the negative thermal expansion member is provided separately from the piston, the amount of the material having a negative linear thermal expansion coefficient can be easily reduced as compared with the case where the piston is made of a material having a negative linear thermal expansion coefficient.

  In the vehicle brake, for example, the negative thermal expansion member has an inclined surface that is inclined with respect to the central axis and can contact the pressing portion.

  According to the above configuration, for example, the force of the translation member that presses the pad against the disk rotor can be adjusted by the angle and shape of the inclined surface.

FIG. 1 is a cross-sectional view of the vehicle brake according to the first embodiment. FIG. 2 is a rear view of the positive thermal expansion member of the vehicle brake according to the first embodiment. FIG. 3 is a cross-sectional view of a part of the vehicle brake according to the first embodiment. FIG. 4 is a cross-sectional view of a part of the vehicle brake according to the first embodiment, and is a diagram illustrating a state of a shape change of each part due to a temperature decrease. FIG. 5 is an explanatory diagram for explaining the shape of the positive thermal expansion member of the vehicle brake according to the first embodiment. FIG. 6 is an explanatory diagram for explaining the shape of the positive thermal expansion member of the reference example. FIG. 7 is a cross-sectional view of a part of the vehicle brake of the reference example. FIG. 8 is a rear view of the positive thermal expansion member of the first modification of the first embodiment. FIG. 9 is a cross-sectional view of a part of a vehicle brake according to a first modified example of the first embodiment, and is a diagram illustrating a state of a shape change of each part due to a temperature decrease. FIG. 10 is a rear view of a positive thermal expansion member according to a second modification of the first embodiment. FIG. 11 is a cross-sectional view of a part of a vehicle brake according to a third modification of the first embodiment. FIG. 12 is a cross-sectional view of a part of the vehicle brake according to the second embodiment.

  Hereinafter, exemplary embodiments of the present invention will be disclosed. A configuration of the embodiment described below, and an operation and a result (effect) provided by the configuration are examples. The present invention can be implemented by configurations other than those disclosed in the following embodiments. Further, according to the present invention, at least one of various effects (including derivative effects) obtained by the configuration can be obtained. Moreover, all the drawings are schematic and exemplary.

  A plurality of embodiments described below include similar components. Therefore, in the following, the same reference numerals are given to the same components, and the duplicate description will be omitted. In the embodiments, similar actions and effects based on similar components are obtained. Also, in the present specification, ordinal numbers are given for the sake of convenience in order to distinguish parts, parts, positions, directions, and the like, and do not indicate priority or order.

  In each of the drawings, a first direction D1 and a second direction D2 are shown. The first direction D1 is a direction along the axial direction of the central axis Ax1 of the cylinder 42, and is a direction in which the piston 43 approaches the disk rotor 11. The second direction D2 is a direction opposite to the first direction D1.

<First embodiment>
FIG. 1 is a sectional view of a vehicle brake 10. As illustrated in FIG. 1, the vehicle brake 10 includes a motor 20, a rotation transmission mechanism 30, a caliper 40 provided with a cylinder 42 and including a rotation / linear motion conversion mechanism 50, and a pair of pads 45. Have. The vehicle brake 10 can operate not only as a hydraulic brake but also as an electric brake. The caliper 40 constitutes a hydraulic brake, and the motor 20, the rotation transmission mechanism 30, the rotation / linear motion conversion mechanism 50, and the caliper 40 constitute an electric brake. The electric brake is a so-called electric parking brake. That is, the vehicle brake 10 is configured such that the braking state by the electric brake function is maintained during parking. However, the electric brake may be operated at the time of running or at the time of temporary stop.

  The pair of pads 45 are spaced from each other in the axial direction of the disk rotor 11 so as to sandwich the disk rotor 11. Each pad 45 is supported by a mounting so as to be movable in the axial direction of the disk rotor 11. Each pad 45 has a back plate 45a and a lining 45b fixed to the back plate 45a. The back plate 45a has a back surface 45aa and a front surface 45ab opposite to the back surface 45aa in the axial direction of the central axis Ax1. The lining 45b has a back surface 45ba overlaid on the front surface 45ab of the back plate 45a, and a front surface 45bb opposite to the back surface 45ba in the axial direction of the central axis Ax1. The surface 45bb contacts the sliding surface 11a of the disk rotor 11. The back plate 45a and the lining 45b are each made of a material having a positive coefficient of linear expansion.

  The rotation of the shaft (not shown) of the motor 20 is transmitted to the rotation member 51 of the rotation / linear motion conversion mechanism 50 via the rotation transmission mechanism 30 having a plurality of rotation elements (not shown) such as gears. The rotation transmission mechanism 30 can also be called a speed reduction mechanism.

  The caliper 40 has a body 41 and a piston 43. The body 41 is supported by mounting so as to be movable in the axial direction of the disk rotor 11. Specifically, the body 41 is attached by a pair of slide pins so as to be movable in the axial direction of the disk rotor 11 with respect to the mounting. The body 41 is made of a material having a positive coefficient of linear expansion. For example, the body 41 is made of a metal such as iron or aluminum. Mounting is an example of a support member.

  The cylinder 42 has a bottomed cylindrical shape opened in the second direction D2 about the central axis Ax1. Specifically, the cylinder 42 has an inner peripheral surface 42a centered on the central axis Ax1. The piston 43 is accommodated in the cylinder 42 so as to be able to reciprocate along the central axis Ax1. The piston 43 is made of a material having a positive coefficient of linear expansion. For example, the piston 43 is made of a metal such as iron or aluminum. Note that the piston 43 may be made of a synthetic resin material such as a phenol resin. The cylinder 42 is provided with a hydraulic chamber R. The hydraulic fluid R flows into and out of the hydraulic pressure chamber R through a brake fluid passage. The piston 43 can move in the first direction D1 by the pressure of the brake fluid in the cylinder 42 and press the pad 45 against the disk rotor 11. Specifically, as the pressure (hydraulic pressure) of the brake fluid in the hydraulic chamber R increases, the piston 43 presses the back plate 45a of the one pad 45 in the first direction D1, and the lining 45b of the one pad 45 Is pressed against one sliding surface 11a of the disk rotor 11. Further, as the pressure of the brake fluid in the hydraulic chamber R increases, the claw 41a provided on the body 41 presses the back plate 45a of the other pad 45 in the second direction D2, and the lining of the other pad 45 45b is pressed against the other sliding surface 11a of the disk rotor 11. As a result, a braking state by the hydraulic brake is obtained in which a wheel (not shown) of the vehicle that rotates integrally with the disk rotor 11 is braked.

  The piston 43 has a wall 43i and a tube 43j. The wall 43i extends in a direction intersecting with the central axis Ax1, and faces the pad 45. The cylindrical portion 43j is formed in a cylindrical shape (cylindrical shape) around the central axis Ax1, and extends from the wall portion 43i to a side opposite to the pad 45. The end of the cylinder 43j opposite to the wall 43i is open. The piston 43 has a concave portion 43a surrounded by a wall portion 43i and a cylindrical portion 43j. The recess 43a is open toward the hydraulic chamber R (second direction D2). The piston 43 has a cylindrical outer peripheral surface 43b, an end surface 43c on the opposite side (first direction D1) from the hydraulic chamber R, and a bottom surface 43p. The outer peripheral surface 43b is also the outer peripheral surface of the cylindrical portion 43j. The end surface 43c is an end surface of the wall portion 43i in the first direction D1, and the bottom surface 43p is an end surface of the wall portion 43i in the second direction D2. The bottom surface 43p faces the second direction D2 and extends in the radial direction of the central axis Ax1. A minute gap (clearance) is set between the outer peripheral surface 43b of the piston 43 and the inner peripheral surface 42a of the cylinder 42. The outer peripheral surface 43b slides on the inner peripheral surface 42a in a lubricated state in which the brake fluid exists in the gap. The bottom surface 43p is an example of a first surface.

  A seal member 72 is interposed between the outer peripheral surface 43b and the inner peripheral surface 42a. The seal member 72 suppresses leakage of the brake fluid from the hydraulic pressure chamber R via a gap. Further, the sealing member 72 draws the piston 43 toward the hydraulic pressure chamber R side (left side in FIG. 2) by elastic force with the decrease of the hydraulic pressure in the hydraulic pressure chamber R, and separates the end face 43 c of the piston 43 from the pad 45. It has a retract function. That is, when the pressing of the piston 43 against the back plate 45a is released with a decrease in the hydraulic pressure of the hydraulic pressure chamber R, the pressing of the lining 45b against the disk rotor 11 by the piston 43 is released, and the hydraulic pressure is thereby reduced. A braking release state by the brake is obtained. Thus, the caliper 40 can operate as a hydraulic brake. The pad 45 is an example of a braking member.

  A rotation / linear motion conversion mechanism 50 is provided inside the caliper 40. The rotation / linear motion conversion mechanism 50 has a rotation member 51 and a linear motion member 52. The rotating member 51 has a coupling portion 51a, a flange 51b, and a shaft 51c, and is supported by the body 41 so as to be rotatable around the central axis Ax1. The coupling portion 51a rotates integrally with an output shaft (not shown) of the rotation transmission mechanism 30. A thrust bearing 71 is provided between the flange 51b and the body 41 of the caliper 40. The shaft 51c protrudes from the flange 51b on the opposite side (first direction D1) from the coupling portion 51a. A male screw portion 51d is provided on the outer peripheral surface of the shaft 51c. The rotating member 51 is made of a material having a positive coefficient of linear thermal expansion.

  The translation member 52 has a cylindrical portion 52a and a projection 52b. The shape of the cylindrical portion 52a is a cylindrical shape centered on the central axis Ax1. A female screw portion 52c is provided on the inner surface (inner peripheral surface) of the cylindrical portion 52a, and the female screw portion 52c and the male screw portion 51d of the rotating member 51 mesh with each other. A pressing portion 52e is provided on an outer peripheral portion of an end of the cylindrical portion 52a in the first direction D1. The pressing portion 52e is formed in an annular shape around the central axis Ax1. The protrusion 52b protrudes outward from the cylindrical portion 52a in the radial direction of the central axis Ax1 (hereinafter sometimes simply referred to as the radial direction). The translation member 52 is made of a material having a positive coefficient of linear thermal expansion. For example, the linear member 52 is made of a metal material such as iron or aluminum.

  The rotation / linear motion conversion mechanism 50 is housed in a concave portion 43 a provided in the piston 43. The translation member 52 is provided movably in the axial direction of the central axis Ax1 (hereinafter, may be simply referred to as the axial direction) in the concave portion 43a.

  The rotation / linear motion conversion mechanism 50 is provided with a rotation stopping mechanism 60 for preventing relative rotation between the linear motion member 52 around the central axis Ax1 and the piston 43. The rotation stopping mechanism 60 has a plurality of rotation stopping protrusions (not shown) provided on the inner peripheral surface 43n of the cylindrical portion 43j of the piston 43, and a projection 52b provided on the linear motion member 52. . The projection 52b is located between two adjacent rotation-stop projections so as to be movable in the axial direction. The rotation preventing convex portion hinders rotation of the projection 52b and thus the translation member 52 by being in contact with the projection 52b in the circumferential direction.

  A positive thermal expansion member 80 is interposed between the linear motion member 52 and the piston 43 in the axial direction of the central axis Ax1. The positive thermal expansion member 80 is separate from the piston 43. The linear motion member 52 can press the piston 43 and thus the pad 45 via the positive thermal expansion member 80 in the first direction D1. The positive thermal expansion member 80 is an example of a positive thermal expansion section.

  As described above, in the present embodiment, the male screw portion 51d of the rotating member 51 and the female screw portion 52c of the linear moving member 52 mesh with each other, and the rotation of the linear moving member 52 is prevented by the rotation stopping mechanism 60. The translation member 52 linearly moves in the axial direction according to the rotation of the rotation member 51. The rotation of the rotating member 51 in one direction based on the rotation of a shaft (not shown) of the motor 20 (hereinafter, referred to as forward rotation) causes the linear motion member 52 to move in the first direction D1, and the piston 43 When the piston 45 is pressed in the first direction D1, the piston 43 presses the lining 45b of one pad 45 against the disk rotor 11. At this time, the claw 41a of the body 41 presses the back plate 45a of the other pad 45 in the second direction D2, and presses the lining 45b of the other pad 45 against the disk rotor 11. As a result, a braking state by the electric brake function is obtained in which a wheel (not shown) of the vehicle that rotates integrally with the disk rotor 11 is braked (FIG. 1). On the other hand, when the linear member 52 moves in the second direction D2 due to the rotation of the rotating member 51 in the reverse direction based on the reverse rotation of the shaft of the motor 20, and the pressing of the piston 43 on the back plate 45a is released, the piston 43 Of the lining 45b against the disk rotor 11 is released, whereby a release state of braking by the electric brake function is obtained (not shown). As described above, the motor 20, the rotation transmission mechanism 30, the rotation / linear motion conversion mechanism 50, and the caliper 40 can operate as an electric brake.

  Next, the positive thermal expansion member 80 will be described in detail. FIG. 2 is a rear view of the positive thermal expansion member 80 of the vehicle brake 10. FIG. 3 is a sectional view of a part of the vehicle brake 10.

  As shown in FIGS. 1 to 3, the positive thermal expansion member 80 is formed in an annular shape around the central axis Ax1. The positive thermal expansion member 80 has an end surface 80a and an inclined surface 80b. The end face 80a is formed in an annular shape around the central axis Ax1. The end face 80a faces the first direction D1 and extends in the radial direction of the central axis Ax1. The end face 80a is arranged on the first direction D1 side with respect to the inclined face 80b, and faces the bottom face 43p of the piston 43. The end surface 80a slides on the bottom surface 43p of the piston 43 due to thermal shrinkage due to a temperature drop. The inclined surface 80b is formed in an annular shape around the central axis Ax1. The inclined surface 80b is inclined with respect to the central axis Ax1 so as to approach the central axis Ax1 in the first direction, and faces inward in the radial direction of the central axis Ax1. Although the inclined surface 80b is shown as a straight line in the cross section of the positive thermal expansion member 80 in FIG. 3, the inclined surface 80b may be a curved surface in the cross section. The positive thermal expansion member 80 is made of a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material of the linear motion member 52. The positive thermal expansion member 80 is made of, for example, an iron-based material such as NCM or a synthetic resin material. The end face 80a is an example of a second face.

  FIG. 4 is a cross-sectional view of a part of the vehicle brake 10, showing a state in which the shape of each part changes with a decrease in temperature. In FIGS. 3 and 4, each part in the case where the temperature of the vehicle brake 10 is higher than a predetermined temperature (normal temperature) is indicated by broken lines. The state shown by the broken line is, for example, a state in which the vehicle brake 10 operates as an electric parking brake immediately after the vehicle brake 10 operates as a hydraulic brake and the vehicle stops. In FIGS. 3 and 4, each part when the temperature of the vehicle brake 10 is normal temperature is indicated by a solid line. The state indicated by the solid line is, for example, a state in which the temperature of each part has decreased after a predetermined time has elapsed since the vehicle brake 10 operated as the electric parking brake. 3 and 4 show, for convenience, thermal deformation of only portions having relatively large linear thermal expansion coefficients.

  As shown in FIGS. 3 and 4, the positive thermal expansion member 80 contracts as the temperature decreases, so as to be interposed between the bottom surface 43 p of the piston 43 and the pressing portion 52 e of the linear motion member 52. Thus, the positive thermal expansion member 80 always presses the pressing portion 52e when the vehicle brake 10 is operating as the electric parking brake. The shape in which the pressing portion 52e can be pressed will be described below.

  FIG. 5 is an explanatory diagram for explaining the shape of the positive thermal expansion member 80 of the vehicle brake 10. In FIG. 5, when the temperature of the vehicle brake 10 is a predetermined temperature (normal temperature), the positive thermal expansion member 80 and the direct acting member 52 are indicated by solid lines, and the temperature of the vehicle brake 10 is lower than the predetermined temperature. The positive thermal expansion member 80 and the linear motion member 52 when they are high are indicated by broken lines. In FIG. 4, in order to explain the shape of the positive thermal expansion member 80, the position of the center axis Ax1 of the end surface 80 a of the positive thermal expansion member 80 is not changed for convenience. As shown in FIG. 4, the shape of the positive thermal expansion member 80 changes in a similar relationship with a change in temperature.

  The positive thermal expansion member 80 has a tangent line L1 to the bottom surface 43p of the inclined surface 80b in a section including the central axis Ax1 and extending in the radial direction of the central axis Ax1. The intersection C1 between the first surface) and the straight line L2 extending in the radial direction of the central axis Ax1 is formed so as to be located on the contact portion 80c side with respect to the central axis Ax1. Since the intersection C1 is formed so as to be located on the contact portion 80c side with respect to the central axis Ax1, the positive thermal expansion member 80 can press the pressing portion 52e as the temperature decreases. The positive thermal expansion member 80 can press the pad 45 in the first direction D1 by a reaction force generated by pressing the pressing portion 52e in the second direction D2 by the inclined surface 80b.

  FIG. 6 is an explanatory diagram for explaining the shape of the positive thermal expansion member 180 of the reference example. FIG. 7 is a cross-sectional view of a part of the vehicle brake of the reference example. The positive thermal expansion member 180 has a tangent line L1 to the bottom surface 43p and a tangent line L1 to the contact portion 80c of the inclined surface 80b that contacts the pressing portion 52e in a section including the central axis Ax1 and including the positive thermal expansion member 180 extending in the radial direction of the central axis Ax1. The intersection C1 with the straight line L2 extending in the radial direction of the overlapping central axis Ax1 is formed so as to be located on the opposite side of the central axis Ax1 from the contact portion 80c. As described above, when the intersection C1 is formed so as to be located on the opposite side to the contact portion 80c with respect to the central axis Ax1, as shown in FIG. 7, the positive thermal expansion member 180 causes the temperature to decrease. Accordingly, the pressing portion 52e cannot be pressed. In addition, in the case of the shape shown in FIGS. 6 and 7, by using a material having a negative coefficient of linear expansion, the pressing portion 52e can be pressed as the temperature decreases.

As shown in FIG. 5, in the positive thermal expansion member 80 of the present embodiment, the radial movement amount Δr of the central axis Ax1 of each point such as the contact portion 80c of the inclined surface 80b due to the temperature change is equal to the positive thermal expansion member. Assuming that a linear expansion coefficient of α is α, a temperature difference is ΔT, and a distance between a radially inner end of the central axis Ax1 and the central axis Ax1 on the inclined surface 80b after the temperature decreases is r, the following equation is used. Is done.
Δr = αrΔT
The axial movement amount Δx of the central axis Ax1 of the contact portion 80c due to the temperature change is represented by the following equation, where θ is the angle between the tangent line L1 and the straight line L2, that is, the angle between the inclined surface 80b and the end surface 80a. It is represented by
Δx = Δrtanθ
= ΑrΔTtanθ
If Δx is equal to or larger than the thermal contraction amount of the pad 45, the positive thermal expansion member 80 can press the pressing portion 52e even when the temperature decreases.

  As described above, in the present embodiment, for example, the vehicle brake 10 includes the positive thermal expansion member 80. The positive thermal expansion member 80 is made of a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material of the linear motion member 52. The positive thermal expansion member 80 has an inclined surface 80b which is inclined with respect to the central axis Ax1 and is capable of pressing the pressing portion 52e in a second direction D2 opposite to the first direction D1 by thermal contraction accompanying a temperature decrease. The pad 45 can be pressed in the first direction D1 by the reaction force generated by the pressing of the pressing portion 52e in the second direction D2 by 80b.

  According to the above configuration, for example, when the pad 45 thermally contracts due to a temperature drop, the positive thermal expansion member 80 also thermally contracts due to a temperature drop, and the inclined surface 80b of the positive thermal expansion member 80 pushes the pressing portion 52e in the first direction D1. In the second direction D2 opposite to the above. As the inclined surface 80b presses the pressing portion 52e in the second direction D2, the positive thermal expansion member 80 presses the pad 45 in the first direction D1 by a reaction force generated at that time. Therefore, according to the above-described configuration, even when the temperature decreases, it is possible to suppress a decrease in the force of the translation member 52 that presses the pad 45 against the disk rotor 11. That is, the occurrence of thermal loosening of the vehicle brake 10 can be suppressed. According to the above configuration, for example, the force of the translation member 52 that presses the pad 45 against the disk rotor 11 can be adjusted by the angle or shape of the inclined surface 80b.

  Further, in the present embodiment, for example, the positive thermal expansion member 80 is made of a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material of the piston 43, and the positive thermal expansion member 80 and the piston 43 extend in the axial direction of the central axis Ax1. It is interposed between the pressing part 52e.

  According to the above configuration, for example, the thermal contraction of the positive thermal expansion member 80 can be easily increased geometrically. Therefore, according to the above configuration, it is easy to increase the force of the linear motion member 52 that presses the pad 45 against the disk rotor 11 when the temperature drops.

  In the present embodiment, an example is shown in which the positive thermal expansion member 80 is separate from the piston 43, but the positive thermal expansion member 80 may be formed integrally with the piston 43. That is, the positive thermal expansion member 80 may be a part of the piston 43.

<Modification>
Next, a modified example of the above embodiment will be described.

  FIG. 8 is a rear view of the positive thermal expansion member 80A of the first modification. FIG. 9 is a cross-sectional view of a part of the vehicle brake 10 of the first modified example, and is a diagram illustrating a state in which the shape of each part changes with a decrease in temperature. The positive thermal expansion member 80A of the first modification has an end surface 80a and an inclined surface 80b, similarly to the positive thermal expansion member 80. However, the positive thermal expansion member 80A is different from the positive thermal expansion member 80 in that it is formed in a disk shape. Specifically, the positive thermal expansion member 80A is provided with a flat plate portion 80g connected to the inner peripheral portion of the inclined surface 80b. According to such a configuration, the shape restoring force when the temperature of the positive thermal expansion member 80A decreases is likely to increase.

  FIG. 10 is a rear view of the positive thermal expansion member 80B of the second modification. The positive thermal expansion member 80B of the second modified example has an end surface 80a (not shown in FIG. 10) and an inclined surface 80b, similarly to the positive thermal expansion member 80. However, the positive thermal expansion member 80B has an annular portion 80d, a flat plate portion 80e, and a plurality of spoke portions 80f. The annular portion 80d includes at least a part of the end surface 80a and the inclined surface 80b, and is formed in an annular shape around the central axis Ax1. The flat portion 80e is located radially inward of the central axis Ax1 with respect to the annular portion 80d. The plurality of spoke portions 80f are spaced from each other in the circumferential direction of the central axis Ax1, and connect the annular portion 80d and the flat plate portion 80e. According to such a configuration, it is easy to achieve both the weight reduction of the positive thermal expansion member 80B and the shape restoring force at the time of temperature decrease.

  FIG. 11 is a cross-sectional view of a part of a vehicle brake 10 according to a third modification. In the third modification, the linear moving member 52A is different from the linear moving member 52 in that the linear moving member 52A includes a main body 52f including a female screw portion 52c and a ball 52g rotatably supported by the main body 52f. A plurality of balls 52g are provided on the outer peripheral portion of the end of the main body 52f in the first direction D1 at intervals from each other in the direction of the central axis Ax1. The ball 52g slides on the inclined surface 80b of the positive thermal expansion member 80. The main body 52f and the ball 52g are made of a material having a positive coefficient of thermal expansion. The ball 52g constitutes a pressing portion 52e. Note that a roller bearing, a needle bearing, a slide bearing, or the like may be provided instead of the plurality of balls 52g. The plurality of balls 52g may have the same configuration as the ball of the ball screw.

  According to the above configuration, the friction between the pressing portion 52e and the inclined surface 80b can be reduced. Therefore, the thermal deformation of the positive thermal expansion member 80 is performed more smoothly.

<Second embodiment>
FIG. 12 is a cross-sectional view of a part of the vehicle brake 10 of the second embodiment. The vehicle brake 10 of the present embodiment has the same configuration as the vehicle brake 10 of the first embodiment. Therefore, also in the present embodiment, the same operation and effect based on the same configuration as the first embodiment can be obtained.

  However, this embodiment is different from the first embodiment in that a negative thermal expansion member 90 is provided instead of the positive thermal expansion member 80.

  The negative thermal expansion member 90 is made of a material having a negative coefficient of linear thermal expansion. For example, the negative thermal expansion member 90 is made of zirconium tungstate. The negative thermal expansion member 90 is interposed between the piston 43 and the pressing portion 52e in the axial direction of the central axis Ax1. Specifically, the negative thermal expansion member 90 has an end surface 90a and an inclined surface 90b. The end face 90a faces the first direction D1 and extends in the radial direction of the central axis Ax1. The inclined surface 90b is inclined with respect to the central axis Ax1 and can contact the pressing portion 52e. The inclined surface 90b is inclined with respect to the central axis Ax1 so as to approach the central axis Ax1 in the second direction D2, and faces outward in the radial direction of the central axis Ax1.

  According to the above configuration, for example, when the pad 45 thermally contracts due to a temperature drop, the negative thermal expansion member 90 thermally expands due to the temperature drop, and presses the piston 43 and thus the pad 45 against the disk rotor 11. Therefore, according to the above-described configuration, even when the temperature decreases, it is possible to suppress a decrease in the force of the translation member 52 that presses the pad 45 against the disk rotor 11. That is, the occurrence of thermal loosening of the vehicle brake 10 can be suppressed.

  In the present embodiment, for example, the negative thermal expansion member 90 has an inclined surface 90b that is inclined with respect to the central axis Ax1 and can contact the pressing portion 52e.

  According to the above configuration, for example, as the inclined surface 90b presses the pressing portion 52e, the negative thermal expansion member 90 presses the pad 45 in the first direction D1. According to the above configuration, for example, the force of the translation member 52 that presses the pad 45 against the disk rotor 11 can be adjusted by the angle and the shape of the inclined surface 90b.

  As described above, the embodiment of the present invention has been exemplified, but the above embodiment is an example, and is not intended to limit the scope of the invention. The above embodiments can be implemented in other various forms, and various omissions, replacements, combinations, and changes can be made without departing from the spirit of the invention. In addition, the specifications (structure, type, direction, shape, size, length, width, thickness, height, number, arrangement, position, material, etc.) of each configuration, shape, etc. may be changed as appropriate. Can be implemented.

DESCRIPTION OF SYMBOLS 10 ... Vehicle brake, 11 ... Disk rotor, 11a ... Sliding surface, 20 ... Motor, 41 ... Body, 43p ... Bottom surface (1st surface), 52 ... Linear member, 80, 80A, 80B ... Positive thermal expansion member (Positive thermal expansion portion), 80a: end surface (second surface), 80b: inclined surface, 80c: contact portion, 90: negative thermal expansion member, 90b: inclined surface, Ax1: central axis, D1: first direction, D2 ... second direction, L1 ... tangent line, L2 ... straight line.

Claims (5)

Motor and
A body provided with a cylinder,
A piston made of a material having a positive linear thermal expansion coefficient, housed in the cylinder, and moved in a first direction along a central axis of the cylinder by a pressure of brake fluid in the cylinder to press a pad against a disk rotor;
A rotating member driven by the motor and a material having a positive linear thermal expansion coefficient, having a pressing portion, moving in the first direction by the rotation of the rotating member, and pressing the pad against the disk rotor; A linear motion member having a linear motion member capable of pressing the piston by the pressing portion,
The linear motion member is made of a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material. A positive heat capable of pressing the pad in the first direction by a reaction force generated by pressing the pressing portion in the second direction by the inclined surface; An inflating section,
A vehicle brake equipped with. The positive thermal expansion section is slid on a first surface extending in the radial direction of the central axis in the second direction, due to thermal contraction due to temperature decrease, closer to the first direction side than the inclined surface. Having a second surface arranged and extending in the radial direction,
In a section including the positive thermal expansion portion extending in the radial direction of the central axis and including the central axis, a tangent line of a contact portion of the inclined surface with the pushing portion overlaps the first surface and a straight line extending in the radial direction. 2. The vehicle brake according to claim 1, wherein an intersection with the center axis is located on the contact portion side with respect to the central axis.   The positive thermal expansion section is separate from the piston, and is made of a material having a positive linear thermal expansion coefficient larger than the linear thermal expansion coefficient of the material of the piston. 3. The vehicle brake according to claim 1, wherein the brake is interposed between the vehicle and the pressing portion. 4. Motor and
A body provided with a cylinder,
A piston made of a material having a positive linear thermal expansion coefficient, housed in the cylinder, and capable of moving in a first direction along a central axis of the cylinder by pressure of brake fluid in the cylinder to press a pad against a disk rotor. When,
A rotating member driven by the motor and a material having a positive linear thermal expansion coefficient, having a pressing portion, moving in the first direction by the rotation of the rotating member, and pressing the pad against the disk rotor; A linear motion member having a linear motion member capable of pressing the piston with the pressing portion,
A negative thermal expansion member formed of a material having a negative linear thermal expansion coefficient and interposed between the piston and the pressing portion in the axial direction of the central axis;
A vehicle brake equipped with. The vehicle brake according to claim 4, wherein the negative thermal expansion member has an inclined surface that is inclined with respect to the central axis and can contact the pressing portion.

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