Reverse input cutoff clutch and reverse input cutoff system

Abstract

The reverse input cutoff clutch (1) includes an input member (2), an output member (3), and an engagement element (5) that engages with an input side engagement portion (25) of the input member (2) and an output side engagement portion (35) of the output member (3). The input side engagement portion (25) has a first contact portion (P1) and a second contact portion (P2) that contact the engagement element (5). The output side engagement portion (35) has output side contact portions (Q1, Q2) that contact the engagement element (5). In the second radial direction (D2), a distance (MI1) between the first contact portion (P1) and the first reference line (L1) is greater than a distance (MO1) between the output side contact portion (Q1) and the first reference line (L1). A distance (MI2) between the second contact portion (P2) and the first reference line (L1) is less than a distance (MO2) between the output side contact portion (Q2) and the first reference line (L1).

Description

[Technical field]

[0001] The present invention relates to a reverse input disconnect clutch and a reverse input disconnect system. This application claims priority based on Japanese Patent Application No. 2023-115097, filed on July 13, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, there is known a reverse input cutoff clutch that includes an input member connected to an input mechanism such as a drive source and an output member connected to an output mechanism such as a reducer, and that allows transmission of rotational torque from the input member to the output member while cutting off reverse input of rotational torque from the output member to the input member, and a reverse input cutoff system that uses this reverse input cutoff clutch. Various techniques have been proposed to improve the performance of these reverse input cutoff clutches and reverse input cutoff systems.

[0003] For example, Patent Document 1 discloses a configuration of a reverse input cutoff clutch having a pressed member having a pressed surface, an input member and an output member provided coaxially with each other on the radial inside of the pressed surface, and a pair of engagement elements interposed between the input member and the output member in a front view and movable in the radial direction. According to the technology described in Patent Document 1, when a rotational torque is reversely input to the output member, the engagement element moves in a direction approaching the pressed surface based on the engagement between the engagement element and the output member, and frictionally engages with the pressed surface, thereby cutting off the rotational torque reversely input to the output member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 168466 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional technology, which transmits torque and blocks (locks) reverse input torque by contact between the input member and the engaging element and between the output member and the engaging element, has the following problems. That is, when a reverse input is applied, depending on the contact position between the input member and the engaging element or the contact position between the output member and the engaging element, the engaging element may not move radially outward easily and may not be locked. Also, when a positive input is applied to release the lock, depending on the contact position between the parts, the torque required to release the lock may increase, and the efficiency of torque transmission may decrease. Therefore, the prior art has had a problem in improving both the locking property against reverse input and the torque transmission efficiency against forward input.

[0006] Therefore, an object of the present invention is to provide a reverse input blocking clutch that can improve both the locking performance against reverse input and the torque transmission efficiency against positive input compared to the prior art, and a reverse input blocking system having this reverse input blocking clutch. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. A reverse input cutoff clutch according to a first aspect of the present invention includes an input member having a housing having a pressed surface on an inner circumferential surface, an input shaft arranged coaxially with the pressed surface, and a pair of input side engaging portions spaced apart from each other in a first radial direction across a central axis of the input shaft, an output member having an output shaft arranged coaxially with the input shaft and an output side engaging portion arranged between the pair of input side engaging portions in the first radial direction, a pressing surface facing the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion. and a pair of engaging elements movable relative to each other along the first radial direction, wherein when a rotational torque is input to the input member, the pair of engaging elements move toward each other radially inward in the first radial direction based on the engagement between the input side engaging portion and the input side engaged portion, and transmit the rotational torque to the output member based on the engagement between the output side engaging portion and the output side engaged portion, and when a rotational torque is reversely input to the output member, the pair of engaging elements move toward each other radially inward in the first radial direction based on the engagement between the output side engaging portion and the output side engaged portion. the input side engaging portions are formed so as to be point-symmetrical with respect to a central axis of the input member when viewed in the axial direction of the input member, and the input side engaging portions have a first contact portion which comes into contact with the engaging element when the rotational torque in a first rotation direction is input to the input member, and a second contact portion which comes into contact with the engaging element when the rotational torque in a second rotation direction opposite to the first rotation direction is input to the input member, The engaging portion has an output side contact portion that comes into contact with the engaging element when the rotational torque is reversely input to the output member, and when a direction perpendicular to both the first radial direction and the central axis of the input member is defined as a second radial direction, the distance between the first contact portion and the center of rotation of the input member along the second radial direction is greater than the distance between the output side contact portion and the center of rotation of the input member along the second radial direction, and the distance between the second contact portion and the center of rotation of the input member along the second radial direction is smaller than the distance between the output side contact portion and the center of rotation of the input member along the second radial direction.

[0008] A reverse input cutting system according to a first aspect of the present invention includes the above-mentioned reverse input cutting clutch, and a ball screw mechanism connected to the output member of the reverse input cutting clutch. Effect of the Invention

[0009] According to the reverse input blocking clutch and reverse input blocking system of the present invention, it is possible to provide a reverse input blocking clutch and a reverse input blocking system having this reverse input blocking clutch that can improve both the locking performance against reverse input and the torque transmission efficiency against positive input compared to the prior art. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a reverse input blocking system according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the reverse input cut-off clutch according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 . [Figure 4] 5 is a schematic diagram for explaining the effect of the reverse input cut-off clutch according to the first embodiment. FIG. [Diagram 5] 5 is a schematic diagram for explaining the effect when the reverse input cutoff clutch according to the first embodiment is unlocked. FIG. [Figure 6] 13 is a schematic diagram for explaining the effect when the reverse input cutoff clutch according to the comparative example is unlocked; FIG. [Figure 7] 13 is a schematic diagram for explaining the effect when the reverse input cutoff clutch according to the comparative example is unlocked; FIG. [Figure 8] FIG. 11 is a cross-sectional view of a reverse input cutoff clutch according to a second embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction of the central axis C of the reverse input cutoff clutch 1. In addition, among the radial directions, a direction along the approaching and separating direction (opposing direction) of a pair of engagement elements described later is sometimes referred to as a first radial direction D1, and among the radial directions, a direction perpendicular to the first radial direction D1 is sometimes referred to as a second radial direction D2.

[0012] (First embodiment) (Reverse input blocking system) FIG. 1 is a schematic configuration diagram of a reverse input blocking system 10 according to the first embodiment. As shown in Fig. 1, a reverse input cutting system 10 of this embodiment is used as an electric caliper brake of a vehicle such as an automobile. The reverse input cutting system 10 is a system for realizing a parking brake function of the electric caliper brake by using a lock function (reverse input cutting function) of a reverse input cutting clutch 1, which will be described in detail later. The reverse input cutting system 10 includes a motor 11, the reverse input cutting clutch 1, a ball screw mechanism 12, and a pair of brake pads 13 that hold a brake disc 14 of the vehicle in between.

[0013] The motor 11 is a drive source in the reverse input cutoff system 10, and an input member 2 (input shaft) (see FIG. 2) of the reverse input cutoff clutch 1 is connected to a rotating shaft of the motor 11. The input from the motor 11 is regarded as a positive input for the reverse input cutoff clutch 1.

[0014] A ball screw mechanism 12 is connected to the output member 3 (output shaft) (see FIG. 2) of the reverse input cutoff clutch 1. The ball screw mechanism 12 has a ball screw shaft 15 connected to the output member 3 of the reverse input cutoff clutch 1, a nut 16 (a linear motion component in the claims) screwed with the ball screw shaft 15, and a sphere 17 disposed between the ball screw shaft 15 and the nut 16. The ball screw mechanism 12 converts the rotational motion input to the ball screw shaft 15 from the motor 11 via the reverse input cutoff clutch 1 into linear motion of the nut 16. The rotating shaft of the motor 11 and the central axis of the ball screw mechanism 12 are both arranged coaxially with the central axis C of the reverse input cutoff clutch 1. In the following description, the motor 11 side as viewed from the reverse input cutoff clutch 1 in the direction along the central axis C may be referred to as a first axial side, and the opposite side (the ball screw mechanism 12 side as viewed from the reverse input cutoff clutch 1) may be referred to as a second axial side.

[0015] Brake pads 13 are connected to nuts 16 of the ball screw mechanism 12. Thus, when the motor 11 is rotated in one direction, the nut 16 and brake pads 13 move toward the second axial direction so as to approach the brake disc 14, and the brake disc 14 is sandwiched between the pair of brake pads 13, thereby braking the vehicle. When the motor 11 is rotated in the other direction, the nut 16 and brake pads 13 move toward the first axial direction so as to move away from the brake disc 14, thereby releasing the brake.

[0016] In this embodiment, the ball screw mechanism 12 is configured so that when the rotating shaft of the motor 11 rotates counterclockwise CCW as viewed from the first axial side, the nut 16 moves to the second axial side, i.e., in a direction approaching the brake disc 14. When the rotating shaft of the motor 11 rotates clockwise CW as viewed from the first axial side, the nut 16 moves to the first axial side, i.e., in a direction away from the brake disc 14.

[0017] Here, since the ball screw mechanism 12 has a good reverse action efficiency, when an axial thrust is applied to the nut 16 due to a reaction force from the brake disc 14, the ball screw shaft 15, which is a rotating part, may rotate. To prevent this, it was conventionally necessary to constantly drive the motor 11 during parking braking to keep the ball screw shaft 15 from rotating. However, since the motor 11 is constantly driven, power consumption tends to increase. Therefore, in the reverse input blocking system 10 of this embodiment, a configuration is adopted in which a ball screw mechanism 12 and a reverse input blocking clutch 1 are used in combination to transmit the positive input from the motor 11 to the ball screw mechanism 12, and the reverse input from the ball screw mechanism 12 to the motor 11 is blocked by the reverse input blocking clutch 1. As a result, the reaction force from the brake disc 14 is blocked by the reverse input blocking clutch 1, making it possible to perform parking braking without constantly driving the motor 11.

[0018] (Reverse input cutoff clutch) The reverse input cutoff clutch 1 will be described in detail below. Fig. 2 is a cross-sectional view of the reverse input cutoff clutch 1 according to the first embodiment, as viewed from a direction perpendicular to the axial direction. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2.

[0019] 2 and 3, the reverse input cutoff clutch 1 includes an input member 2, an output member 3, a housing 4, a pair of engagers 5, and an elastic member 6. The reverse input cutoff clutch 1 transmits the rotational force input to the input member 2 to the output member 3. On the other hand, the reverse input cutoff clutch 1 has a reverse input cutoff function of cutting off the rotational force reversely input to the output member 3 and not transmitting it to the input member 2, or of transmitting only a portion of the rotational force to the input member 2 and cutting off the remainder.

[0020] (Input member) The input member 2 is connected to a rotating shaft of a motor 11 (see FIG. 1). A rotational force from the motor 11 is input to the input member 2. The input member 2 has an input shaft body 21 (an input shaft in the claims) and a pair of arms 23. The input shaft body 21 is formed in a columnar (or cylindrical) shape centered on a central axis C.

[0021] The pair of arms 23 extend from the input shaft body 21 toward the second side in the axial direction. The arms 23 are integrally formed with the input shaft body 21. The arms 23 are provided in pairs at both ends of the input shaft body 21 in the first radial direction D1. The arms 23 are provided at a position slightly offset radially outward from the input shaft body 21. Here, as shown in FIG. 3, a straight line passing through the central axis C and parallel to the first radial direction D1 is defined as a first reference line L1. Also, a straight line passing through the central axis C and parallel to a second radial direction D2 perpendicular to the first radial direction D1 and the axial direction is defined as a second reference line L2. At this time, the arms 23 are formed in shapes asymmetric to each other with respect to the first reference line L1. Also, the pair of arms 23 are formed to have shapes point-symmetric to each other with respect to the central axis C when viewed from the axial direction. Specifically, the arm portion 23 has a substantially flat input side engagement portion 25 facing the radially inner side in the first radial direction D1, a curved surface portion 26 facing the radially outer side in the first radial direction D1, and a side surface portion 27 provided only on one side in the second radial direction D2 with respect to the first reference line L1. The curved surface portion 26 is formed in an arc shape that is convex toward the radially outer side in the first radial direction D1. The side surface portion 27 connects the ends of the input side engagement portion 25 and the curved surface portion 26 to each other. With respect to the first reference line L1, on the other side in the second radial direction D2 where the side surface portion 27 is not present, the end of the input side engagement portion 25 and the end of the curved surface portion 26 are directly connected.

[0022] A plurality of arm portions 23 are provided in accordance with the number of engaging elements 5 described below. In this embodiment, a pair of arm portions 23 is provided in accordance with the provision of a pair of engaging elements 5. The number of arm portions 23 is not limited to two, and the number of arm portions 23 may be one, or three or more, in accordance with the number of engaging elements 5.

[0023] (Output component) As shown in Fig. 2, the output member 3 is connected to a ball screw shaft 15 (see Fig. 1) of the ball screw mechanism 12, and outputs a rotational force (rotational torque) from the motor 11. The output member 3 is disposed coaxially with the input member 2. As shown in Figs. 2 and 3, the output member 3 has an output shaft main body 31 (output shaft in the claims) and an insertion portion 32. The output shaft main body 31 is formed in a columnar (or cylindrical) shape centered on the central axis C.

[0024] The insertion portion 32 extends from an end portion on a first side in the axial direction of the output shaft body 31 toward the first side in the axial direction. The insertion portion 32 is integrally formed with the output shaft body 31. The insertion portion 32 is a portion inserted between a pair of engaging elements 5 described later, and is disposed radially inward from a pair of arm portions 23 of the input member 2. In this embodiment, the base end portion of the insertion portion 32 inserted between the pair of engaging elements 5 (for example, a portion located on the second side in the axial direction from the retaining ring 39 in FIG. 2) is formed in a plate shape. The shape of the base end portion of the insertion portion 32 is not limited to a plate shape. The tip portion of the insertion portion 32 (for example, a portion located on the first side in the axial direction from the retaining ring 39) is formed in a cylindrical shape. The tip portion of the insertion portion 32 is fitted to the input member 2 via a bearing 46 so as to be relatively rotatable. The bearing 46 is, for example, a rolling bearing or a sliding bearing.

[0025] As shown in Fig. 3, the outer peripheral surface of the base end of the insertion portion 32 has a pair of output side engaging portions 35 facing both sides in the thickness direction (first radial direction D1) of the insertion portion 32, and a pair of side surface portions 36 connecting the ends of the pair of output side engaging portions 35. Each output side engaging portion 35 is formed of a flat surface along the second radial direction D2. Each output side engaging portion 35 faces a pair of engaging elements 5. The output side engaging portion 35 is provided radially inward in the first radial direction D1 than the input side engaging portion 25 of the input member 2. The pair of side surface portions 36 connect both ends of the output side engaging portion 35 to each other.

[0026] The insertion portion 32 has a plurality of output side engaging portions 35 and side surface portions 36 provided in accordance with the number of engaging elements 5 described below. In this embodiment, a pair of output side engaging portions 35 and side surface portions 36 are provided in accordance with the provision of a pair of engaging elements 5. The number of output side engaging portions 35 is not limited to two, and the number of output side engaging portions 35 may be one, or three or more, in accordance with the number of engaging elements 5.

[0027] (housing) The housing 4 is formed in a cylindrical shape. The housing 4 is fixed to another member (not shown) and its rotation is restricted. The housing 4 is arranged coaxially with the input member 2 and the output member 3. The housing 4 accommodates the input member 2, the output member 3, and a pair of engagement elements 5. The housing 4 has a first accommodation hole 41, a second accommodation hole 42, and a pressed surface 40.

[0028] As shown in FIG. 2, the first accommodating hole 41 penetrates the housing 4 in the axial direction. The first accommodating hole 41 is formed coaxially with the central axis C. The first accommodating hole 41 is provided on a second axial side of the housing 4. The output shaft body 31 of the output member 3 is accommodated inside the first accommodating hole 41. The inner diameter of the first accommodating hole 41 is larger than the outer shape of the output shaft body 31 of the output member 3. The first accommodating hole 41 rotatably holds the output member 3 via a bearing 45.

[0029] The second accommodating hole 42 is provided on a first side in the axial direction of the housing 4. The second accommodating hole 42 is formed coaxially with the central axis C. The second accommodating hole 42 is provided on a first side in the axial direction of the first accommodating hole 41. The inner diameter of the second accommodating hole 42 is larger than the inner diameter of the first accommodating hole 41. Thus, a stepped through hole is formed on the inside of the housing 4 by the first accommodating hole 41 and the second accommodating hole 42. The arm portion 23 of the input member 2 is accommodated inside the second accommodating hole 42. The insertion portion 32 of the output member 3 is accommodated inside the second accommodating hole 42 and further inside the arm portion 23. The inner diameter of the second accommodating hole 42 is larger than the outer shape of the pair of arm portions 23 of the input member 2. Inside the second accommodating hole 42, the input member 2 is accommodated so as to be rotatable relative to the housing 4.

[0030] The inner circumferential surface of the second accommodating hole 42 is the pressed surface 40. The pressed surface 40 is formed so as to be coaxial with the central axis C. An input side engagement portion 25 of the input member 2 and an output side engagement portion 35 of the output member 3 are provided on the radially inner side of the pressed surface 40.

[0031] (engager) 2 and 3, the pair of engaging elements 5 are configured in a semicircular shape and disposed radially inside the housing 4. The pair of engaging elements 5 face each other in the first radial direction D1 and are configured to be movable toward and away from each other in the first radial direction D1. Each of the pair of engaging elements 5 has a pressing surface 51, a bottom surface 52, an input side engaged portion 55, and an output side engaged portion 56.

[0032] As shown in FIG. 3, the pressing surface 51 is a radially outer surface that presses the pressed surface 40 of the housing 4, and is a convex surface in the shape of a circular arc. A part of the outer circumferential surface of the engaging element 5 that faces the pressed surface 40 may be the pressing surface 51. The pressing surface 51 presses the pressed surface 40 when the reverse input cutoff clutch 1 is in a locked state (a state in which the reverse input from the output member 3 is cut off). The radius of curvature of the pressing surface 51 is equal to or smaller than the radius of curvature of the pressed surface 40. Two pressing surfaces 51 are provided for each engaging element 5, and are formed so that the frictional engagement force between the engaging element 5 and the pressed surface 40 is large due to the wedge effect. The two pressing surfaces 51 are provided at positions spaced apart from each other in the circumferential direction of the engaging element 5. The pressing surface 51 may be directly formed by the entire or part of the outer circumferential surface of the engaging element 5, or may be formed to have a surface property with a larger friction coefficient than the other parts of the engaging element 5. For example, the pressing surface 51 may be formed of a friction material fixed to the engaging element 5 by sticking or bonding. Each pressing surface 51 of the engaging element 5 faces the inner side of the housing 4 in the radial direction.

[0033] The bottom surface 52 of the engaging element 5 is provided radially inward in the first radial direction D1 from the pressing surface 51. The bottom surface 52, together with an output-side engaged portion 56 of the engaging element 5, which will be described in detail later, forms a straight portion of the semicircular engaging element 5. In this embodiment, the bottom surface 52 is formed in a substantially flat surface shape except for a pair of protrusions 59, which will be described later. The bottom surfaces 52 of the pair of engaging elements 5 face each other in the first radial direction D1. The inner diameter dimension of the pressed surface 40 and the outer dimensions of the engaging elements 5 are set so that, when the pair of engaging elements 5 are positioned inside the housing 4, a gap exists between the pressed surface 40 and the pressing surface 51, and at least one of the gaps exists between the pair of bottom surfaces 52 and the output member 3.

[0034] The input side engaged portion 55 is a hole that penetrates the center of the engaging element 5 in the axial direction when viewed from the axial direction. The input side engaged portion 55 is formed in the shape of an elongated hole extending in the second radial direction D2. The arm portion 23 of the input member 2 is inserted into the input side engaged portion 55. The input side engaged portion 55 engages with the arm portion 23. The input side engaged portion 55 has a size that allows the arm portion 23 of the input member 2 to be loosely inserted. Specifically, the input side engaged portion 55 is formed so that a gap exists between the arm portion 23 and the inner peripheral surface of the input side engaged portion 55 when the arm portion 23 of the input member 2 is inserted inside the input side engaged portion 55. Therefore, in a neutral state in which the engaging element 5 is not locked and no rotational torque is input, the arm portion 23 can be slightly displaced in the rotation direction of the input member 2 relative to the input side engaged portion 55 (i.e., the engaging element 5), and the engaging element 5 can be slightly displaced in the first radial direction D1 relative to the arm portion 23.

[0035] The output side engaged portion 56 is provided near the radial center in the second radial direction D2 of the straight line portion (bottom surface 52) of the engaging element 5 formed in a semicircular shape. The output side engaged portion 56 is provided radially inward in the first radial direction D1 than the input side engaged portion 55. The output side engaged portion 56 engages with the insertion portion 32 of the output member 3. The output side engaged portion 56 is formed in the shape of a flat surface that is continuous with the bottom surface 52.

[0036] Furthermore, a pair of protrusions 59 protruding from the bottom surface 52 toward the other engaging element 5 are integrally formed on the bottom surface 52 of the engaging element 5. The pair of protrusions 59 are provided on the bottom surface 52 of the engaging element 5 in a pair spaced apart from each other in the second radial direction D2. The pair of protrusions 59 are provided inward from the end of the bottom surface 52 and outward from the output-side engaged portion 56 in the second radial direction D2. The protrusion height of the protrusions 59 is set to a height such that, for example, in an unlocked state of the engaging element 5 (a state in which transmission of a rotational force from the input member 2 to the output member 3 is permitted), the protrusions 59 of the pair of engaging elements 5 facing each other in the first radial direction D1 face each other with a gap in the first radial direction D1.

[0037] 2 and 3, in a state in which the reverse input cutoff clutch 1 is assembled, the arm portion 23 of the input member 2 is axially inserted into each of the input side engaged portions 55 of the pair of engaging elements 5, and the insertion portion 32 of the output member 3 is axially inserted between the output side engaged portions 56 of the pair of engaging elements 5. In other words, the pair of engaging elements 5 are disposed so that the output side engaged portions 56 sandwich the insertion portion 32 of the output member 3 from the radially outer side.

[0038] 2, end plates 38 for positioning each member in the axial direction are provided on both axial sides of the engaging element 5. Furthermore, a retaining ring 39 for positioning each member is provided on a first axial side of the engaging element 5. In addition to the positioning function, components such as end plates 38 may be provided to have a function of preventing contact between the engaging element 5 and the output member 3 and the input member 2, for example, to suppress wear.

[0039] (Elastic material) As shown in Fig. 3, the elastic member 6 is arranged so as to be elastically sandwiched between the engagement piece 5 and the output member 3. The elastic member 6 is, for example, a leaf spring. The elastic member 6 biases the engagement piece 5 radially outward in the first radial direction D1, i.e., in a direction approaching the pressed surface 40. The elastic member 6 is, for example, formed in a flat plate shape as a whole. Notches (not shown) are formed at both ends of the elastic member 6 in the second radial direction D2. A pair of protrusions 59 of the engagement piece 5 fit into these notches, respectively, to position the elastic member 6. The elastic member 6 does not necessarily have to be provided. However, the configuration of this embodiment having the elastic member 6 is advantageous in that the biasing force of the elastic member 6 can suppress rattling caused by gaps between the components, and the biasing force of the elastic member 6 makes it easier for the engaging pieces 5 to move radially outward in the first radial direction D1, making it easier to lock the reverse input.

[0040] Next, the contact portions between the input member 2 or the output member 3 and the engagement element 5 and their positional relationship will be described. As shown in FIG. 3, when viewed from the axial direction, the input side engaging portion 25 of the input member 2 has a first contact portion P1 and a second contact portion P2. The first contact portion P1 is provided near the boundary between the input side engaging portion 25 and the curved surface portion 26. When a torque in the counterclockwise direction CCW (the first rotation direction in the claims) is input to the input member 2, the input member 2 rotates in the counterclockwise direction CCW and the first contact portion P1 comes into contact with the engaging element 5. Here, the counterclockwise direction CCW is the rotation direction of the rotation torque input to the input member 2 when the brake is operated. That is, in this embodiment, for example, the rotation direction when the motor 11 is driven to press the brake pad 13 toward the brake disc 14 is the counterclockwise direction CCW. Also, the rotation direction when the brake is released is the clockwise direction CW. The second contact portion P2 is provided near the boundary between the input side engaging portion 25 and the side surface portion 27. The second contact portion P2 comes into contact with the engaging element 5 when a rotational torque in a clockwise direction CW (a second rotation direction in the claims) is input to the input member 2. A distance MI1 along the second radial direction D2 from the first reference line L1 to the first contact portion P1 (hereinafter, the input side first distance MI1) is greater than a distance MI2 along the second radial direction D2 from the first reference line L1 to the second contact portion P2 (hereinafter, the input side second distance MI2) (MI1>MI2).

[0041] When viewed from the axial direction, the output side engagement portion 35 of the output member 3 has a third contact portion Q1 (output side contact portion in claims) and a fourth contact portion Q2 (output side contact portion in claims). The third contact portion Q1 is provided in the same region as the corresponding first contact portion P1 in the four regions partitioned by the first reference line L1 and the second reference line L2. The third contact portion Q1 is provided in the vicinity of the boundary between the output side engagement portion 35 and the side surface portion 36. The third contact portion Q1 comes into contact with the engagement piece 5 when a rotational torque in the clockwise direction CW is input to the output member 3. Here, the clockwise direction CW is the rotational direction of the rotational torque that is reversely input to the output member 3. In this embodiment, for example, the direction in which the ball screw shaft 15 tries to rotate due to the reaction force from the brake disc 14 is the clockwise direction CW. Therefore, in this embodiment, the rotational direction of the reverse input torque acting on the reverse input cutoff clutch 1 is mainly the clockwise direction CW. The fourth contact portion Q2 is provided in the same region as the corresponding second contact portion P2 in the four regions defined by the first reference line L1 and the second reference line L2. The fourth contact portion Q2 is provided near the boundary between the output side engagement portion 35 and the side surface portion 36. The fourth contact portion Q2 comes into contact with the engagement piece 5 when a rotational torque in the counterclockwise direction CCW is input to the output member 3. A distance MO1 from the first reference line L1 to the third contact portion Q1 along the second radial direction D2 (hereinafter, output side first distance MO1) is equal to a distance MO2 from the first reference line L1 to the fourth contact portion Q2 along the second radial direction D2 (hereinafter, output side second distance MO2) (MO1=MO2). In the following description, when the third contact portion Q1 and the fourth contact portion Q2 are not distinguished from each other, they may be collectively referred to as output side contact portions.

[0042] In this case, the input side first distance MI1 is larger than the output side first distance MO1 (MI1>MO1). Also, the input side second distance MI2 is smaller than the output side second distance MO2 (MI2 <MO2)。

[0043] Furthermore, when a rotational torque is input in reverse to the output member 3 and the pair of pressing surfaces 51 are in contact with the pressed surface 40, the output side contact portions Q1, Q2 are located closer to the rotation center C of the output member 3 in the first radial direction D1 than the virtual straight line LH connecting the contact portion P5 between one of the pair of pressing surfaces 51 and the pressed surface 40 and the rotation center C of the output member 3.

[0044] (Reverse input cutoff clutch operation) Next, the operation of the reverse input cutoff clutch 1 and the reverse input cutoff system 10 of this embodiment will be described with reference to the respective drawings. First, a case where the motor 11 (see FIG. 1) is driven to activate the brake will be described. When it is desired to activate the brake, the motor 11 is first rotated in the counterclockwise direction CCW. As shown in FIG. 3, when a rotational force is input from the motor 11 to the input member 2, the arm portion 23 of the input member 2 rotates in the counterclockwise direction CCW around the central axis C. Then, the first contact portion P1 comes into contact with the engaging element 5 and presses the inner surface of the input side engaged portion 55 radially inward in the first radial direction D1, whereby the pair of engaging elements 5 move closer to each other. Then, the insertion portion 32 of the output member 3 is clamped from both radial sides by the output side engaged portions 56 of the pair of engaging elements 5 that have approached each other.

[0045] As a result, the output side engaging portion 35 of the insertion portion 32 in the output member 3 and the bottom surface 52 of the engaging element 5 become substantially parallel, and the insertion portion 32 and the pair of output side engaged portions 56 are engaged without any rattling. Therefore, the rotational torque input to the input member 2 is transmitted to the output member 3 via the pair of engaging elements 5, and is output from the output member 3 to the ball screw mechanism 12. Then, as the ball screw shaft 15 of the ball screw mechanism 12 rotates counterclockwise CCW, the nut 16 and the brake pad 13 move axially toward the brake disc 14. As a result, the brake disc 14 is clamped by the brake pad 13, and the brake is applied.

[0046] Next, a case where a reaction force from the brake disc 14 acts after the brake is applied will be described. That is, a case where a thrust force toward the first side in the axial direction is generated in the nut 16 of the ball screw mechanism 12, and a reverse input acts on the reverse input cutoff clutch 1 via the ball screw shaft 15 due to this thrust force will be described. When a rotational torque is reversely input to the output member 3, the insertion portion 32 of the output member 3 rotates in the clockwise direction CW inside the pair of output side engaged portions 56. Then, the third contact portion Q1 abuts against the engaging element 5 and presses the output side engaged portion 56 toward the radially outward side in the first radial direction D1, and as a result, the pair of engaging elements 5 move in a direction approaching the pressed surface 40. Then, the pressing surface 51 of each of the pair of engaging elements 5 is pressed against the pressed surface 40 of the housing 4. At this time, the pressing surface 51 and the pressed surface 40 are frictionally engaged over the entire range or at least a part of the circumferential direction of the pressing surface 51.

[0047] As a result, the rotational force reversely input to the output member 3 is either completely blocked by being transmitted to the housing 4 fixed to another member (not shown) and not transmitted to the input member 2, or only a portion of the rotational force reversely input to the output member 3 is transmitted to the input member 2 and the remainder is blocked. Particularly in this embodiment, the reverse input is completely blocked and not transmitted to the input member 2. Therefore, even when the driving of the motor 11 is stopped, it is possible to suppress the rotation of the ball screw shaft 15 caused by the generation of a reaction force from the brake disc 14. This makes it possible to perform parking braking using the reverse input cutoff clutch 1.

[0048] Next, a case where the motor 11 (see FIG. 1) is driven again to release the brake will be described. When it is desired to release the brake, the motor 11 is first rotated in the clockwise direction CW. As shown in FIG. 3, when a rotational force is input from the motor 11 to the input member 2, the arm portion 23 of the input member 2 rotates in the clockwise direction CW around the central axis C. Then, the second contact portion P2 comes into contact with the engaging element 5 and presses the inner surface of the input side engaged portion 55 radially inward in the first radial direction D1, whereby the pair of engaging elements 5 move closer to each other. Then, the insertion portion 32 of the output member 3 is clamped from both radial sides by the output side engaged portions 56 of the pair of engaging elements 5 that have approached each other.

[0049] As a result, the output side engaging portion 35 of the insertion portion 32 in the output member 3 and the bottom surface 52 of the engaging element 5 become substantially parallel, and the insertion portion 32 and the pair of output side engaged portions 56 are engaged without any rattling. Therefore, the rotational torque input to the input member 2 is transmitted to the output member 3 via the pair of engaging elements 5, and is output from the output member 3 to the ball screw mechanism 12. Then, as the ball screw shaft 15 of the ball screw mechanism 12 rotates in the clockwise direction CW, the nut 16 and the brake pad 13 move in the axial direction away from the brake disc 14. As a result, the brake pad 13 moves away from the brake disc 14, and the brake is released.

[0050] In the reverse input cutoff clutch 1 of this embodiment, the size of the gap between each of the components is adjusted so that the above-mentioned operation is possible. For example, when a rotational torque is input in reverse to the output member 3, and the pressing surface 51 of the engaging element 5 contacts the pressed surface 40 (locked state), the input member 2 is located in a neutral position. The neutral position of the input member 2 is a position where the input side engaging portion 25 of the arm portion 23 is not in contact with the input side engaged portion 55, or the input side engaging portion 25 is in contact with the input side engaged portion 55 but no force is transmitted. In other words, a gap is provided between the input side engaging portion 25 of the arm portion 23 and the inner surface of the input side engaged portion 55, which allows the pressing surface 51 to press the pressed surface 40 based on the contact portion Q1 of the output member 3 pressing the output side engaged portion 56. This prevents the engaging element 5 from being prevented from moving radially outward by the arm portion 23 when a rotational torque is input in reverse to the output member 3. Furthermore, even after the pressing surface 51 comes into contact with the pressed surface 40, the surface pressure acting on the contact portion between the pressing surface 51 and the pressed surface 40 changes according to the magnitude of the rotational torque input inversely to the output member 3, thereby ensuring that the output member 3 is locked or semi-locked appropriately.

[0051] Furthermore, in the reverse input cutoff clutch 1 of this embodiment, the input side first distance MI1 is made larger than the output side first distance MO1, the input side second distance MI2 is made smaller than the output side second distance MO2, and the output side contact parts Q1, Q2 are positioned closer to the rotation center C of the output member 3 in the first radial direction D1 than the virtual straight line LH. By setting each dimension value in this manner, it is possible to more smoothly switch from the unlocked state or semi-unlocked state to the locked state or semi-locked state, and switch from the locked state or semi-locked state to the unlocked state or semi-unlocked state. The reason for this will be described with reference to Figures 4 to 7.

[0052] FIG. 4 is a schematic diagram for explaining the effect of the reverse input cutoff clutch 1 according to the first embodiment. FIG. 5 is a schematic diagram for explaining the effect when the reverse input cutoff clutch 1 according to the first embodiment is unlocked. FIG. 4 is a schematic diagram for explaining the effect when the reverse input is cut off when a reverse input torque in the clockwise direction CW acts in FIG. 3. FIG. 5 is a schematic diagram for explaining the effect when a rotational torque T in the clockwise direction CW is input from the input member 2 to release the locked state in a state in which the reverse input is cut off by the engagement between the pressing surface 51 and the pressed surface 40 (locked state of the reverse input cutoff clutch 1). The upward arrow acting on the third contact portion Q1 in FIG. 5 is the reverse input torque generated by the reaction force from the brake disc 14 in the locked state.

[0053] As shown in Fig. 4, when the input-side first distance MI1 is greater than the output-side first distance MO1 (MI1>MO1), when a rotational torque in the clockwise direction CW (reverse input) is input to the output member 3, the engaging element 5 tends to rotate in the counterclockwise direction CCW around the third contact portion Q1. As shown by a trajectory r in Fig. 4 with a dashed line, the pressing surface 51 of the pair of pressing surfaces 51 located on the opposite side of the third contact portion Q1 (the right side in Fig. 4) across the second reference line L2 in the second radial direction D2 tends to be strongly pressed against and bite into the pressed surface 40. As a result, the engaging element 5 becomes more likely to be locked by the engagement between the pressing surface 51 and the pressed surface 40, and the rotational torque in the clockwise direction CW inputted in the reverse direction to the output member 3 becomes more likely to be blocked.

[0054] On the one hand, when unlocking, as shown in FIG. 5, when the input-side second distance MI2 is smaller than the output-side second distance MO2 (MI2 < MO2), and the third contact portion Q1 is located closer to the rotation center C of the output member 3 than the virtual straight line LH with respect to the first radial direction D1, when a clockwise CW rotation torque T is input to the input member 2, each contact portion P5 of the engaging member 5 tends to rotate clockwise CW about the third contact portion Q1. At this time, as shown by the phantom lines r1 and r2 in FIG. 5, neither of the pair of pressing surfaces 51 is pressed against the pressed surface 40. Therefore, when switching from the locked state or the semi-locked state to the unlocked state, the rotation torque of the input member 2 does not increase instantaneously. That is, the generation of peak torque is suppressed. As a result, the switching from the locked state or the semi-locked state to the unlocked state is smoothly performed with a small torque. Also, since no peak torque is generated when unlocking, there is no need to unnecessarily increase the maximum output torque of the motor 11, and the enlargement of the motor 11 and the increase in power consumption can be suppressed.

[0055] Here, FIG. 6 is a schematic diagram for explaining the effect when unlocking the reverse input blocking clutch 801 according to the comparative example. Similar to FIG. 5, FIG. 6 is a schematic diagram for explaining the effect when the reverse input is blocked by the engagement of the pressing surface 51 and the pressed surface 40 (the locked state of the reverse input blocking clutch 1), and a clockwise CW rotational torque T is input from the input member 2 to release the locked state. As shown in FIG. 6, even when the input-side second distance MI2 is smaller than the output-side second distance MO2 (MI2 < MO2), when the third contact portion Q1 is located on the side farther from the rotation center C of the output member 3 with respect to the first radial direction D1 than the virtual straight line LH, when a clockwise CW rotational torque T is input to the input member 2, the engaging element 5 tends to rotate clockwise CW about the third contact portion Q1. Then, as shown by the locus r3 in a dashed line in FIG. 6, among the pair of pressing surfaces 51, the pressing surface 51 located on the side closer to the third contact portion Q1 than the first reference line L1 with respect to the second radial direction D2 (the contact portion P5 on the left side in FIG. 6) is strongly pressed against the pressed surface 40 and tends to bite in. In order to release such biting of the pressing surface 51 into the pressed surface 40, when switching from the locked state or the semi-locked state to the unlocked state, the rotational torque of the input member 2 instantaneously increases. That is, a peak torque is likely to occur when unlocking.

[0056] Therefore, as a result of comparing the configuration of the present embodiment shown in FIG. 5 with the comparative example shown in FIG. 6, according to the configuration of the present embodiment in which the input-side second distance MI2 is smaller than the output-side second distance MO2 (MI2 < MO2) and the third contact portion Q1 is located on the side closer to the rotation center C of the output member 3 with respect to the first radial direction D1 than the virtual straight line LH, as described above, the generation of the peak torque can be suppressed. Therefore, when a clockwise CW rotational torque T is input to the input member 2 to release the locked state, it is possible to improve the unlocking performance as compared with the comparative example.

[0057] 7 is a schematic diagram for explaining the effect when the reverse input cutoff clutch 901 according to another comparative example is unlocked. Similar to FIG. 5, FIG. 7 is a schematic diagram for explaining the effect when a rotational torque T in the clockwise direction CW is input from the input member 2 to release the locked state in a state in which the reverse input is cut off by the engagement between the pressing surface 51 and the pressed surface 40 (the reverse input cutoff clutch 1 is in a locked state).

[0058] Hereinafter, the difference between the reverse input cutoff clutch 1 of this embodiment shown in FIG. 5 and the reverse input cutoff clutch 901 of the comparative example shown in FIG. 7 and the operation and effect thereof will be described. As shown by the downward arrows in FIG. 5 and FIG. 7, when a rotational torque in the clockwise direction CW is input to the input member 2 in the locked state, the engagement piece 5 tends to rotate along the clockwise direction CW. At this time, in this embodiment shown in FIG. 5, if the inputted rotational torque is T and the distance along the second radial direction D2 from the first reference line L1 to the second contact portion P2 is A, the load F1 acting on the engagement piece 5 at the second contact portion P2 can be expressed as F1=T / A. Similarly, as shown in FIG. 7, if the inputted rotational torque is T and the distance along the second radial direction D2 from the first reference line L1 to the second contact portion P2 is B, the load F2 acting on the engagement piece 5 at the second contact portion P11 can be expressed as F2=T / B. Here, A <Bである。

[0059] Therefore, when the distance A from the first reference line L1 to the second contact portion P2 along the second radial direction D2 is relatively small (see FIG. 5), the load generated at the second contact portion P2 when the same rotational torque T is applied is larger than when the distance B from the first reference line L1 to the second contact portion P11 along the second radial direction D2 is relatively large (see FIG. 7). Therefore, according to the configuration of this embodiment shown in FIG. 5, since the input side second distance MI2 is smaller than the input side first distance MI1, the rotational torque required when switching from the locked state or the semi-locked state to the unlocked state can be reduced. Therefore, according to the configuration of this embodiment in which the contact portion (second contact portion P2) on the clockwise CW side, which is the rotational direction of the input member 2 when unlocked, is disposed closer to the first reference line L1 than the first contact portion P1, the unlocking performance can be improved compared to the comparative example.

[0060] (Action, effect) According to the reverse input cutoff clutch 1 of this embodiment, the distance between the first contact portion P1 and the rotation center of the input member 2 in the second radial direction D2 (input side first distance MI1) is greater than the distance between the output side contact portion Q1 and the rotation center of the input member 2 in the second radial direction D2 (output side first distance MO1). As a result, when a rotational torque (reverse input) in the clockwise direction CW is input to the output member 3, the engagement piece 5 tends to rotate in the counterclockwise direction CCW around the output side contact portion Q1. Therefore, one of the pair of pressing surfaces 51 (the opposite side to the output side contact portion Q1 across the first reference line L1 in the second direction) tends to be strongly pressed against the pressed surface 40 and bite into it. Therefore, the reverse input in the second rotation direction can be effectively cut off, and the locking performance can be improved. Also, the distance between the second contact portion P2 and the rotation center of the input member 2 in the second radial direction D2 (input side second distance MI2) is smaller than the distance between the output side contact portion Q2 and the rotation center of the input member 2 in the second radial direction D2 (output side second distance MO2). As a result, when a rotation torque in the clockwise direction CW is input to the input member 2, the engagement element 5 tends to rotate in the clockwise direction CW around the output side contact portion Q1. That is, the pair of pressing surfaces 51 are pressed in a direction away from the pressed surface 40. Therefore, when switching from the locked state or the semi-locked state to the unlocked state, the peak torque does not become instantaneously large, and the switching from the locked state or the semi-locked state to the unlocked state can be smoothly performed. Also, since the pair of pressing surfaces 51 are not pressed against the pressed surface 40, the rotation torque in the second rotation direction from the input member 2 can be efficiently transmitted to the engagement element 5 and the output member 3. Therefore, particularly when the rotational direction of the torque input to the output member 3 and the input member 2 is the same (clockwise CW in this embodiment), the rotational torque from the input member 2 can be efficiently transmitted while effectively blocking reverse input from the output member 3. Therefore, it is possible to provide a reverse input cutoff clutch 1 that can improve both the locking performance against reverse input and the torque transmission efficiency against forward input as compared with the prior art.

[0061] The third contact portion Q1 and the fourth contact portion Q2 of the output member 3 are equal in distance from the first reference line L1 along the second radial direction D2. Also, the distance MI1 between the first contact portion P1 and the first reference line L1 along the second radial direction D2 and the distance MI2 between the second contact portion P2 and the first reference line L1 along the second radial direction D2 are different from each other. In this way, by making the distances from the first reference line L1 of the first contact portion P1 and the second contact portion P2 different from each other, the distance MI1 between the first contact portion P1 and the first reference line L1 can be made larger than the distance MO1 between the output side contact portion Q1 and the first reference line L1, and the distance MI2 between the second contact portion P2 and the first reference line L1 can be made smaller than the distance MO2 between the output side contact portion Q2 and the first reference line L1. Therefore, even if the shape of the output side engagement portion 35 is made symmetrical in the left-right direction and the top-bottom direction, the rotational torque from the input member 2 can be efficiently transmitted while effectively blocking the reverse input from the output member 3.

[0062] The output side contact portion is located closer to the rotation center C of the output member 3 in the first radial direction D1 than the virtual straight line LH. As a result, when a positive input is applied from the input member 2 along the clockwise direction CW, the pressing surface 51 can be pressed in a direction that makes it easier to separate from the pressed surface 40, compared to when the output side contact portions Q1 and Q2 are located farther from the rotation center C of the output member 3 in the first radial direction D1 than the virtual straight line LH. This suppresses an increase in peak torque when a positive input is applied to the input member 2, and allows smooth switching from the locked state or semi-locked state to the unlocked state. In addition, since the pair of pressing surfaces 51 are more unlikely to be pressed against the pressed surface 40, the rotation torque from the input member 2 along the clockwise direction CW can be efficiently transmitted.

[0063] The rotation direction of the rotational torque input in reverse to the output member 3 coincides with the second rotation direction (clockwise CW). This makes it possible to stably obtain the above-mentioned advantageous effect of efficiently transmitting the rotational torque from the input member 2 while effectively blocking the reverse input from the output member 3. Therefore, in particular when the rotation directions of the torque input to the output member 3 and the input member 2 are both clockwise CW, it is possible to effectively improve both the locking property against the reverse input and the torque transmission efficiency against the normal input compared to the conventional technology.

[0064] According to the reverse input cutoff system 10 of this embodiment, the reverse input cutoff system 10 includes the above-mentioned reverse input cutoff clutch 1 and a ball screw mechanism 12. Here, the ball screw mechanism 12 has a ball screw shaft 15, which is a rotating part, and a nut 16, which is a linear motion part, and the nut 16 moves linearly as the ball screw shaft 15 rotates. However, if the ball screw mechanism 12 has good reverse efficiency, there is a risk that the ball screw shaft 15 will rotate when the nut 16 is pressed. Therefore, by using the ball screw mechanism 12 in combination with the reverse input cutoff clutch 1, unintended rotation of the ball screw shaft 15 and movement of the nut 16 can be suppressed even when a ball screw mechanism 12 with good reverse efficiency is used. Therefore, it is possible to provide a high-performance reverse input cutoff clutch 1 equipped with a reverse input cutoff clutch 1 that can improve both the locking property against reverse input and the torque transmission efficiency against forward input compared to the conventional technology. Also, by using the reverse input cutoff clutch 1 in combination with the ball screw mechanism 12, the ball screw mechanism 12 can be used more suitably and the versatility of the system using the ball screw mechanism 12 can be increased.

[0065] The reverse input cutoff system 10 includes a motor 11 connected to an input member 2 of a reverse input cutoff clutch 1 and a brake pad 13 connected to a nut 16 of a ball screw mechanism 12, and performs parking braking of an electric caliper brake using a locking function of the reverse input cutoff clutch 1. By providing the reverse input cutoff clutch 1 between the motor 11 and the ball screw mechanism 12, when a reaction force acting on the brake pad 13 from a brake disc 14 is transmitted to the reverse input cutoff clutch 1 via the ball screw mechanism 12, the rotation of the ball screw shaft 15 of the ball screw mechanism 12 can be locked (cut off) by the reverse input cutoff clutch 1. This allows the position of the brake pad 13 to be maintained even when the power of the motor 11 is turned off. Therefore, the power consumption of the motor 11 can be reduced compared to an electric caliper brake that does not use the reverse input cutoff clutch 1. Therefore, the reverse input blocking system 10 can be suitably used by employing it in an electric caliper brake, particularly one with a parking brake function.

[0066] Second embodiment Next, a second embodiment of the present invention will be described. In the following description, the same components as those in the first embodiment described above will be denoted by the same reference numerals and will not be described as necessary. The specific components are not limited to these embodiments and can be modified as appropriate without departing from the gist of the present invention. FIG. 8 is a cross-sectional view of a reverse input cutoff clutch 201 according to a second embodiment. FIG. 8 is a cross-sectional view of a cross section corresponding to FIG. 3 of the first embodiment. In the second embodiment, the shape of the arm portion 23 of the input member 202 and the shape of the insertion portion 32 of the output member 203 as viewed from the axial direction are different from those in the first embodiment described above.

[0067] In the second embodiment, the arm portion 23 of the input member 202 is formed in a trapezoid shape with one side curved when viewed in the axial direction. Specifically, the arm portion 23 has an input side engagement portion 25 facing inward in the radial direction, a curved surface portion 26 facing outward in the radial direction, and two side surface portions 27, 27 connecting ends of the input side engagement portion 25 and the curved surface portion 26. The curved surface portion 26 is formed in an arc shape centered on the central axis C.

[0068] The input side engagement portion 25 of the input member 202 has a first contact portion P201 and a second contact portion P202. The first contact portion P201 is provided near the boundary between one end of the input side engagement portion 25 and the side surface portion 27. The first contact portion P201 comes into contact with the engagement piece 5 when a rotational torque in the counterclockwise direction CCW is input to the input member 202. The second contact portion P202 is provided near the boundary between the other end of the input side engagement portion 25 and the side surface portion 27. The second contact portion P202 comes into contact with the engagement piece 5 when a rotational torque in the clockwise direction CW is input to the input member 202.

[0069] In this embodiment, the distance MI201 (input side first distance MI201) along the second radial direction D2 from the first reference line L1 to the first contact portion P201 is equivalent to the distance MI202 (input side second distance MI202) along the second radial direction D2 from the first reference line L1 to the second contact portion P202 (MI201=MI202).

[0070] Moreover, the insertion portion 32 of the output member 203 is formed in a parallelogram shape when viewed in the axial direction. Specifically, the insertion portion 32 has a pair of output-side engagement portions 35 facing the pair of engagement elements 5, respectively, and a pair of side portions 36 connecting the ends of the output-side engagement portions 35. The pair of side portions 36 are inclined with respect to the output-side engagement portions 35. The pair of side portions 36 are parallel to each other.

[0071] The output side engagement portion 35 of the output member 203 has a third contact portion Q201 and a fourth contact portion Q202. The third contact portion Q201 is provided in the same region as the first contact portion P201 in the four regions defined by the first reference line L1 and the second reference line L2. The third contact portion Q201 is provided near the boundary between the output side engagement portion 35 and the side surface portion 36. The third contact portion Q201 comes into contact with the engagement piece 5 when a rotational torque in the clockwise CW is input to the output member 203. The fourth contact portion Q202 is provided in the same region as the second contact portion P202 in the four regions defined by the first reference line L1 and the second reference line L2. The fourth contact portion Q202 is provided near the boundary between the output side engagement portion 35 and the side surface portion 36. The fourth contact portion Q202 comes into contact with the engagement piece 5 when a rotational torque in the counterclockwise direction CCW is input to the output member 203.

[0072] In this embodiment, a distance MO201 (output side first distance MO201) along the second radial direction D2 from the first reference line L1 to the third contact portion Q201 is smaller than a distance MO202 (output side second distance MO202) along the second radial direction D2 from the first reference line L1 to the fourth contact portion Q202 (MO201 <MO202)。

[0073] By providing the contact portions P201, P202, Q201, and Q202 at the above-mentioned positions, in the second embodiment, as in the first embodiment, the input-side first distance MI201 is greater than the output-side first distance MO201 (MI201>MO201). Also, the input-side second distance MI202 is smaller than the output-side second distance MO202 (MI202 <MO202)。

[0074] According to the reverse input cutoff clutch 201 of the second embodiment, the first contact portion P201 and the second contact portion P202 have the same distances MI201 and MI202 along the second radial direction D2 from the first reference line L1. Also, the distance MO201 along the second radial direction D2 between the third contact portion Q201 and the first reference line L1 and the distance MO202 along the second radial direction D2 between the fourth contact portion Q202 and the first reference line L1 are different from each other. As a result, even if the shape of the input side engagement portion 25 is symmetrical, the input side first distance MI201 can be made larger than the output side first distance MO201, and the input side second distance MI202 can be made smaller than the output side second distance MO202. Therefore, even if the shape of the input side engagement portion 25 is symmetrical, the same effect as the first embodiment can be obtained. That is, the rotational torque from the input member 202 can be efficiently transmitted while effectively cutting off the reverse input from the output member 203. Furthermore, since a configuration different from that of the first embodiment can be used, the degree of freedom in the shape of the input side engaging portion 25 is improved, and the versatility of the reverse input cutoff clutch 201 can be improved.

[0075] In addition, in FIG. 8, the shape of the engaging element 5 is illustrated in a simplified manner, but for example, the engaging element 5 having the same shape as that of the first embodiment may be used.

[0076] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in each of the above-described embodiments, the contact parts P1, P2, Q1, and Q2 are arranged so that the unlocking property is improved when the input member 2 rotates in the same direction (clockwise CW) as the direction in which the reverse input torque is generated among the rotation directions of the input member 2, but this is not limited to the above. For example, when the direction in which the reverse input torque is generated is counterclockwise CCW, the positional relationship of the contact parts P1, P2, Q1, and Q2 may be changed so that the unlocking property is improved when the input member 2 rotates counterclockwise CCW compared to when the input member 2 rotates clockwise CW. In addition, the contact parts P1, P2, Q1, and Q2 may be arranged so that the unlocking property is improved when the input member 2 is rotated in the opposite direction to the direction in which the reverse input torque is generated.

[0077] The configuration of the ball screw mechanism 12 is not limited to the configuration of the above-mentioned embodiment. For example, a nut 16 may be connected to the output member 3 of the reverse input cutoff clutch 1, and the ball screw shaft 15 may be connected to the brake pad 13.

[0078] The reverse input cutoff clutch 1 and the reverse input cutoff system 10 of the above-described embodiment may be applied to a system other than a parking brake of an electric brake. For example, they may be applied to a system in which the direction in which the reverse input torque is generated is not constant. However, when the rotation direction of the reverse input is constant, such as a parking brake, the reverse input cutoff clutch 1 is formed so that it is easier to lock with respect to that rotation direction, and both the locking property and the transmission efficiency can be improved, so the configuration of this embodiment in which the reverse input cutoff clutch 1 is used as a parking brake of an electric brake in combination with a ball screw mechanism 12 is advantageous.

[0079] In each of the above-described embodiments, the reverse input cutoff clutch 1 is a linkless type that does not use a link structure as a reverse input cutoff mechanism, but the present invention is not limited to this. A link type reverse input cutoff clutch that uses a link mechanism, which is a known technology, may be used as the reverse input cutoff mechanism.

[0080] The present disclosure may also be implemented in the following combinations: (1) a housing having a pressure receiving surface on an inner circumferential surface; an input member including an input shaft arranged coaxially with the pressed surface and a pair of input side engaging portions spaced apart from each other in a first radial direction across a central axis of the input shaft; an output member including an output shaft arranged coaxially with the input shaft and an output side engaging portion provided between the pair of input side engaging portions in the first radial direction; a pair of engaging members each having a pressing surface opposed to the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion, the pair of engaging members being movable relative to each other along the first radial direction; Equipped with When a rotational torque is input to the input member, the pair of engagement elements move toward each other radially inward in the first radial direction based on the engagement between the input side engagement portion and the input side engaged portion, and transmit the rotational torque to the output member based on the engagement between the output side engagement portion and the output side engaged portion, When a rotational torque is input in reverse to the output member, the pair of engagement pieces move away from each other toward the radially outward direction in the first radial direction based on the engagement between the output side engagement portion and the output side engaged portion, thereby frictionally engaging the pressed surface and the pressing surface, The pair of input side engagement portions are formed to have shapes that are point symmetrical with each other about a central axis of the input member when viewed in the axial direction of the input member, The input side engagement portion is a first contact portion that comes into contact with the engagement element when the rotational torque in a first rotation direction is input to the input member; a second contact portion that comes into contact with the engagement element when the rotational torque in a second rotational direction that is opposite to the first rotational direction is input to the input member; having the output-side engagement portion has an output-side contact portion that comes into contact with the engagement element when the rotational torque is reversely input to the output member, When a direction perpendicular to both the first radial direction and the central axis of the input member is defined as a second radial direction, a distance between the first contact portion and a rotation center of the input member along the second radial direction is greater than a distance between the output side contact portion and a rotation center of the input member along the second radial direction, a distance between the second contact portion and a rotation center of the input member along the second radial direction is shorter than a distance between the output side contact portion and a rotation center of the input member along the second radial direction; Reverse input cut-off clutch. (2) The output side contact portion is a third contact portion provided in the same region as the first contact portion in four regions defined by a first reference line passing through a central axis of the input member and parallel to the first radial direction and a second reference line passing through the central axis of the input member and parallel to the second radial direction; a fourth contact portion provided in the same region as the second contact portion among four regions defined by the first reference line and the second reference line; having the third contact portion and the fourth contact portion are formed to have equal distances from a rotation center of the input member along the second radial direction. The reverse input cut-off clutch described in (1). (3) a distance between the first contact portion and a rotation center of the input member along the second radial direction is greater than a distance between the second contact portion and a rotation center of the input member along the second radial direction; A reverse input cut-off clutch according to (1) or (2). (4) The output side contact portion is a third contact portion provided in the same region as the first contact portion in four regions defined by a first reference line passing through a central axis of the input member and parallel to the first radial direction and a second reference line passing through the central axis of the input member and parallel to the second radial direction; a fourth contact portion provided in the same region as the second contact portion among four regions defined by the first reference line and the second reference line; having The first contact portion and the second contact portion are formed to have equal distances from a rotation center of the input member along the second radial direction. The reverse input cut-off clutch described in (1). (5) When the rotational torque is reversely input to the output member and the pair of pressing surfaces are in contact with the pressed surface, the output side contact portion is located closer to the rotation center of the output member in the first radial direction than a virtual line connecting a contact portion between one of the pair of pressing surfaces and the pressed surface and a rotation center of the output member. A reverse input cut-off clutch according to any one of (1) to (4). (6) A rotation direction of the rotational torque reversely input to the output member is the same as the second rotation direction. A reverse input cut-off clutch according to any one of (1) to (5). (7) A reverse input cutoff clutch according to any one of (1) to (6); a ball screw mechanism connected to the output member of the reverse input cutoff clutch; Equipped with Reverse input blocking system. (8) a motor connected to the input member of the reverse input cutoff clutch; a brake pad connected to a linear motion component of the ball screw mechanism and sandwiching the brake disc; Equipped with The reverse input cutoff clutch has a lock function to perform parking braking of the electric caliper brake. A reverse input blocking system as described in (7). [Explanation of symbols]

[0081] 1,201,801,901 Reverse input cutoff clutch 2 Input member 3 Output member 4. Housing 5 Engagement element 10. Reverse input blocking system 11 Motor 12 Ball screw mechanism 13. Brake pads 14 Brake disc 16 Nut (linear motion part) 21 Input shaft body (input shaft) 25 Input side engagement part 31 Output shaft body (output shaft) 35 Output side engagement part 40 Pressed surface 51 Pressing surface 55 Input side engaged part 56 Output side engaged part CCW Counterclockwise (first rotation direction) CW Clockwise (second rotation direction) D1 First radial direction D2 Second radial direction L1 First reference line L2 Second reference line LH Virtual straight line MI1, MI201 Input side first distance MO1,MO210 Output side first distance MI2, MI202 Input side second distance MO2,NO202 Output side second distance P1,P201 First contact part P2,P202 Second contact part Q1,Q201 Third contact part (output side contact part) Q2,Q202 Fourth contact part (output side contact part)

Claims

1. a housing having a pressure receiving surface on an inner circumferential surface; an input member including an input shaft arranged coaxially with the pressed surface and a pair of input side engagement portions spaced apart from each other in a first radial direction across a central axis of the input shaft; an output member including an output shaft arranged coaxially with the input shaft and an output side engaging portion provided between the pair of input side engaging portions in the first radial direction; a pair of engaging members each having a pressing surface opposed to the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion, the pair of engaging members being movable relative to each other along the first radial direction; Equipped with When a rotational torque is input to the input member, the pair of engagement elements move toward each other radially inward in the first radial direction based on the engagement between the input side engagement portion and the input side engaged portion, and transmit the rotational torque to the output member based on the engagement between the output side engagement portion and the output side engaged portion, When a rotational torque is input in reverse to the output member, the pair of engagement pieces move away from each other toward the radially outward direction in the first radial direction based on the engagement between the output side engagement portion and the output side engaged portion, thereby frictionally engaging the pressed surface and the pressing surface, The pair of input side engagement portions are formed to have shapes that are point symmetrical with each other about a central axis of the input member when viewed in the axial direction of the input member, The input side engagement portion is a first contact portion that comes into contact with the engagement element when the rotational torque in a first rotation direction is input to the input member; a second contact portion that comes into contact with the engagement element when the rotational torque in a second rotational direction that is opposite to the first rotational direction is input to the input member; having the output-side engagement portion has an output-side contact portion that comes into contact with the engagement element when the rotational torque is reversely input to the output member, When a direction perpendicular to both the first radial direction and the central axis of the input member is defined as a second radial direction, a distance between the first contact portion and a rotation center of the input member along the second radial direction is greater than a distance between the output side contact portion and a rotation center of the input member along the second radial direction, a distance between the second contact portion and a rotation center of the input member along the second radial direction is shorter than a distance between the output side contact portion and a rotation center of the input member along the second radial direction; Reverse input cut-off clutch.

2. The output side contact portion is a third contact portion provided in the same region as the first contact portion in four regions defined by a first reference line passing through a central axis of the input member and parallel to the first radial direction and a second reference line passing through the central axis of the input member and parallel to the second radial direction; a fourth contact portion provided in the same region as the second contact portion among four regions defined by the first reference line and the second reference line; having the third contact portion and the fourth contact portion are formed to have equal distances from a rotation center of the input member along the second radial direction.

2. The reverse input cut-off clutch according to claim 1.

3. a distance between the first contact portion and a rotation center of the input member along the second radial direction is greater than a distance between the second contact portion and a rotation center of the input member along the second radial direction; 2. The reverse input cut-off clutch according to claim 1.

4. The output side contact portion is a third contact portion provided in the same region as the first contact portion in four regions defined by a first reference line passing through a central axis of the input member and parallel to the first radial direction and a second reference line passing through the central axis of the input member and parallel to the second radial direction; a fourth contact portion provided in the same region as the second contact portion among four regions defined by the first reference line and the second reference line; having The first contact portion and the second contact portion are formed to have equal distances from a rotation center of the input member along the second radial direction.

2. The reverse input cut-off clutch according to claim 1.

5. When the rotational torque is reversely input to the output member and the pair of pressing surfaces are in contact with the pressed surface, the output side contact portion is located closer to the rotation center of the output member in the first radial direction than a virtual line connecting a contact portion between one of the pair of pressing surfaces and the pressed surface and a rotation center of the output member.

2. The reverse input cut-off clutch according to claim 1.

6. A rotation direction of the rotational torque reversely input to the output member is the same as the second rotation direction.

2. The reverse input cut-off clutch according to claim 1.

7. A reverse input cutoff clutch according to any one of claims 1 to 6; a ball screw mechanism connected to the output member of the reverse input cutoff clutch; Equipped with Reverse input blocking system.

8. a motor connected to the input member of the reverse input cutoff clutch; a brake pad connected to a linear motion component of the ball screw mechanism and sandwiching the brake disc; Equipped with The reverse input cutoff clutch has a lock function to perform parking braking of the electric caliper brake.

8. The reverse input blocking system of claim 7.

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