Reverse-direction locking coupling

Abstract

A reverse-direction locking clutch comprises a housing, an input shaft, an output shaft, a pair of engagement elements, a first bearing mechanism located between the input shaft and the housing, and a second bearing mechanism located between the output shaft and the housing. At least one of the input shaft, output shaft, and housing has a running surface that contacts at least one rolling element of the first bearing mechanism and the second bearing mechanism.

Description

Reverse input cutoff clutch

[0001] This application claims priority from Japanese Patent Application No. 2022-62585, filed April 4, 2022, the contents of which are incorporated herein by reference.

[0002] Conventionally, there has been known a reverse input cutoff clutch configuration that includes an input shaft connected to an input mechanism such as a drive source and an output shaft connected to an output mechanism such as a reducer, and that allows transmission of rotational force from the input shaft to the output shaft and cuts off transmission of rotational force from the output shaft to the input shaft. Various techniques have been proposed for improving the performance of these reverse input cutoff clutches.

[0003] For example, Patent Document 1 discloses the configuration of a locking reverse input blocking clutch that blocks reverse input from the output shaft by preventing rotation of the output shaft. The reverse input blocking clutch includes an input shaft and an output shaft that are coaxially arranged, a pressed member having a pressed surface, and a pair of engaging elements that are movable in the radial direction. According to the technology described in Patent Document 1, when a rotational force is reversely input to the output shaft, the engaging elements move toward the pressed surface based on engagement between the engaging elements and the output shaft, thereby frictionally engaging with the pressed surface, thereby blocking the rotational force reversely input to the output shaft.

[0004] Japanese Patent No. 6658965

[0005] However, in the above-mentioned conventional technology, if the input shaft, output shaft, and pressed member are not coaxially aligned, the gap between the input shaft and the engaging element, or between the engaging element and the pressed surface, will be different, which may result in performance degradation due to uneven contact, etc.

[0006] For example, if the coaxiality between the input shaft and the pressed member is poor, the size of the gap between each engaging element and the input shaft will be different. As a result, when a rotational force is input to the input shaft, only one engaging element will contact the input shaft first, and torque will be concentrated on that engaging element until the other engaging element contacts the input shaft. This may result in a decrease in performance due to wear, vibration, or foreign matter contamination. Furthermore, if the coaxiality between the output shaft and the pressed member is poor, the size of the gap between each engaging element and the pressed member will be different. As a result, when a rotational force is input in reverse to the output shaft, only one engaging element will contact the pressed member first, and the pressing force will be weak until the other engaging element contacts the output shaft, preventing the locking function from functioning properly. This may result in a time loss until the locking mechanism is locked. Furthermore, if only one engaging element contacts the output shaft, bending of the output shaft may occur, resulting in a decrease in performance.

[0007] Therefore, the conventional technology described in Patent Document 1 has room for improvement in terms of improving the performance of the reverse input cutoff clutch.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a reverse input cutoff clutch that can improve coaxiality and stabilize performance.

[0009] 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 a housing having a pressed surface, an input shaft provided radially inward from the pressed surface, an output shaft provided radially inward from the pressed surface, and a pair of engaging elements that are relatively movable in the radial direction, each of the pair of engaging elements having a first engaging portion facing the input shaft, a second engaging portion facing the output shaft, and a sliding portion facing the pressed surface, and when a rotational force is input to the input shaft, the pair of engaging elements move toward each other radially inward based on engagement between the input shaft and the first engaging portion. and transmits the rotational force to the output shaft based on the engagement between the second engaging portion and the output shaft, and when the rotational force is input in reverse to the output shaft, the pair of engaging elements move radially outward so as to move away from each other based on the engagement between the output shaft and the second engaging portion, and the pressed surface and the sliding portion frictionally engage with each other, and at least one of the input shaft, the output shaft, and the housing has a raceway surface that comes into contact with the rolling elements of at least one of a first bearing mechanism between the input shaft and the housing and a second bearing mechanism between the output shaft and the housing.

[0010] According to the reverse input cutoff clutch of the present invention, it is possible to improve the coaxiality and stabilize the performance.

[0011] 1. A cross-sectional view of the reverse input cutoff clutch according to the first embodiment. A cross-sectional view taken along line II-II in FIG. 1. An exploded perspective view of the reverse input cutoff clutch according to the first embodiment. A cross-sectional view of the reverse input cutoff clutch according to the second embodiment. A cross-sectional view of the reverse input cutoff clutch according to the third embodiment. A cross-sectional view of the reverse input cutoff clutch according to the fourth embodiment. A cross-sectional view of the reverse input cutoff clutch according to the fifth embodiment. A cross-sectional view of the reverse input cutoff clutch according to the sixth embodiment. A cross-sectional view of the reverse input cutoff clutch according to the seventh embodiment. A cross-sectional view of the reverse input cutoff clutch according to the eighth embodiment.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction of the center axis C of the reverse input cutoff clutch 1, unless otherwise specified.

[0013] (First Embodiment) (Reverse Input Cutoff Clutch) Fig. 1 is a cross-sectional view of a reverse input cutoff clutch 1 according to a first embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is an exploded perspective view of the reverse input cutoff clutch 1 according to the first embodiment. As shown in Figs. 1 to 3, the reverse input cutoff clutch 1 includes an input shaft 2, an output shaft 3, a housing 4, a pair of engagers 5, and a plurality of bearing mechanisms 7, 8. The reverse input cutoff clutch 1 transmits rotational force input to the input shaft 2 to the output shaft 3. On the other hand, the reverse input cutoff clutch 1 has a reverse input cutoff function that cuts off rotational force reversely input to the output shaft 3 and does not transmit it to the input shaft 2, or that transmits only a portion of the rotational force to the input shaft 2 and cuts off the remainder.

[0014] (Input Shaft) The input shaft 2 is connected to an input mechanism such as an electric motor (not shown). Rotational force from the input mechanism is input to the input shaft 2. As shown in FIGS. 1 and 3 , in this embodiment, the input shaft 2 has an input shaft body 21, a base portion 22, and a pair of arms 23. The input shaft body 21 is provided on the input mechanism side in the axial direction. The input shaft body 21 is formed in a columnar (or cylindrical) shape centered on the central axis C. In the following description, the side of the input shaft 2 that is connected to the input mechanism may be referred to as the first axial side, and the opposite side may be referred to as the second axial side.

[0015] The pedestal portion 22 is provided at the second axial end of the input shaft body 21. The pedestal portion 22 is formed integrally with the input shaft body 21. The pedestal portion 22 is formed in a disk shape having an outer diameter larger than that of the input shaft body 21.

[0016] The arm portion 23 extends axially from the base portion 22 toward the opposite side from the input shaft body 21 (i.e., the second axial side). The arm portion 23 is integrally formed with the base portion 22. As shown in FIG. 3 , a pair of arm portions 23 are provided at both radial ends of the base portion 22. Thus, the arm portion 23 is provided at a position offset radially outward from the input shaft body 21. As shown in FIG. 2 , the arm portion 23 is formed in a trapezoidal shape with one curved side when viewed axially. Specifically, the arm portion 23 has a flat portion 25 facing radially inward, a curved portion 26 facing radially outward, and two side portions 27, 27 connecting the ends of the flat portion 25 and the curved portion 26. The curved portion 26 is formed in an arc shape centered on the central axis C.

[0017] A plurality of arms 23 are provided in accordance with the number of engaging elements 5, which will be described later. In this embodiment, a pair of arms 23 is provided in accordance with the number of engaging elements 5. The number of arms 23 is not limited to two, and may be one, or three or more, in accordance with the number of engaging elements 5.

[0018] (Output Shaft) The output shaft 3 is connected to an output mechanism such as a reducer (not shown) and outputs rotational force (rotational torque). The output shaft 3 is arranged coaxially with the input shaft 2. As shown in FIGS. 1 and 3 , the output shaft 3 has an output shaft main body 31 and an insertion portion 32. The output shaft main body 31 is provided on the output mechanism side in the axial direction (second axial side). The output shaft main body 31 is formed in a columnar (or cylindrical) shape centered on the central axis C.

[0019] The insertion portion 32 extends from a first axial end of the output shaft body 31 toward the first axial side. The insertion portion 32 is integrally formed with the output shaft body 31. As shown in FIGS. 1 and 2 , the insertion portion 32 is inserted between a pair of engaging elements 5 (described later) and is disposed radially inward of a pair of arm portions 23 of the input shaft 2. The insertion portion 32 is formed in a flat shape that is smaller in outer diameter than the output shaft body 31. As shown in FIG. 2 , the outer peripheral surface of the insertion portion 32 has an arcuate surface 35, side surfaces 36 on both sides in the minor axis direction (the up-down direction in FIG. 2 ), and guide surfaces 37 on both sides in the major axis direction (the left-right direction in FIG. 2 ).

[0020] The arc surface 35 is formed in an arc shape centered on the central axis C. Each side surface 36 is connected to an end of the arc surface 35 and is formed of a flat surface perpendicular to the minor axis direction of the insertion portion 32. Each side surface 36 faces a pair of engaging elements 5. The guide surfaces 37 are arranged on both sides of the side surfaces 36, and are configured so that the guide surfaces 37 between the side surfaces 36 on both sides are continuous in the minor axis direction to form one convex curved surface. Specifically, the guide surfaces 37 are formed in an arc shape centered on the central axis C.

[0021] The insertion portion 32 is provided with a plurality of side surfaces 36 and guide surfaces 37 in accordance with the number of engaging elements 5 described below. In this embodiment, a pair of side surfaces 36 and guide surfaces 37 is provided in accordance with the number of engaging elements 5. The number of side surfaces 36 is not limited to two, and the number of side surfaces 36 may be one, or three or more, in accordance with the number of engaging elements 5.

[0022] (Housing) As shown in Figures 1 and 2, the housing 4 is hollow and disk-shaped, and is fixed to another member (not shown) to restrict its rotation. The housing 4 is disposed coaxially with the input shaft 2 and the output shaft 3. The housing 4 accommodates the input shaft 2, the output shaft 3, and a pair of engagement elements 5. The housing 4 of this embodiment has a first housing 41 and a second housing 42. The first housing 41 and the second housing 42 of this embodiment are formed from the same material.

[0023] The first housing 41 is disposed on a first side in the axial direction. The first housing 41 accommodates the input shaft 2 therein. The first housing 41 holds the input shaft 2 rotatably about the central axis C via a first bearing mechanism 7 (described later). The second housing 42 is disposed on a second side in the axial direction relative to the first housing 41. The second housing 42 accommodates the output shaft 3 and a pair of engaging elements 5 therein. The second housing 42 holds the output shaft 3 rotatably about the central axis C via a second bearing mechanism 8 (described later). An inner circumferential surface of the second housing 42 is provided with a pressed surface 77 coaxial with the central axis C. The engaging elements 5 are provided inside the pressed surface 77. The first housing 41 and the second housing 42 configured in this manner are joined to each other by a spigot joint, as will be described in detail below.

[0024] Specifically, the first housing 41 has a cylindrical portion 43, a flange portion 44, and an end plate portion 45. The cylindrical portion 43 is provided at a position axially corresponding to the input shaft main body 21 of the input shaft 2. The inner circumferential surface of the cylindrical portion 43 is formed to be coaxial with the input shaft 2. The input shaft 2 is held on the inner circumferential surface of the cylindrical portion 43. A portion of the inner circumferential surface of the cylindrical portion 43 forms a bearing receiving portion 47 in which a first bearing mechanism 7 (described later) is provided.

[0025] The flange portion 44 is located axially at a position corresponding to the arm portion 23 of the input shaft 2. The flange portion 44 is connected to the second axial end of the cylindrical portion 43 and is located axially further toward the second axial side than the cylindrical portion 43. The inner diameter of the flange portion 44 is larger than the inner diameter of the cylindrical portion 43. The inner circumferential surface of the flange portion 44 is formed coaxially with the input shaft 2. The flange portion 44 has a first spigot fitting surface 48 on the inner circumferential surface on the second axial side. The first spigot fitting surface 48 is formed by a cylindrical surface centered on the central axis C. The first spigot fitting surface 48 has an inner diameter dimension that allows it to fit securely with a second spigot fitting surface 78 provided on the second housing 42 (described later). Fitting securely with no play includes, for example, a case where they are fitted to each other with a clearance sufficient to allow for dimensional tolerances during manufacturing. The first spigot fitting surface 48 and the bearing receiving portion 47 of the cylindrical portion 43 are formed coaxially.

[0026] The end plate portion 45 is provided between the cylindrical portion 43 and the flange portion 44 in the axial direction. The end plate portion 45 is formed in a disk shape along a plane perpendicular to the central axis C. In other words, the end plate portion 45 extends in the radial direction, thereby connecting the cylindrical portion 43 and the flange portion 44, which have different diameters, in the radial direction.

[0027] The second housing 42 has a cylindrical small-diameter cylindrical portion 71 and a cylindrical large-diameter cylindrical portion 72. The small-diameter cylindrical portion 71 is located axially corresponding to the output shaft main body 31 of the output shaft 3. The inner circumferential surface of the small-diameter cylindrical portion 71 is formed coaxially with the output shaft 3. The output shaft 3 is held by the inner circumferential surface of the small-diameter cylindrical portion 71. A portion of the inner circumferential surface of the small-diameter cylindrical portion 71 forms a bearing receiving portion 74 in which a second bearing mechanism 8 (described later) is provided. Furthermore, as shown in FIG. 3 , a plurality of (eight in this embodiment) fastening holes 75 are formed circumferentially in the second axial end surface of the small-diameter cylindrical portion 71. The fastening holes 75 are formed so that their depth direction coincides with the axial direction. The second housing 42 is fixed (connected) to another component by bolts inserted into the fastening holes 75.

[0028] The large diameter cylindrical portion 72 is provided at a position in the axial direction corresponding to the insertion portion 32 of the output shaft 3. The large diameter cylindrical portion 72 is connected to a first axial end of the small diameter cylindrical portion 71 and is provided on the first axial side of the small diameter cylindrical portion 71. The inner diameter of the large diameter cylindrical portion 72 is larger than the inner diameter of the small diameter cylindrical portion 71. The inner circumferential surface of the large diameter cylindrical portion 72 is formed so as to be coaxial with the output shaft 3. The output shaft 3 and a pair of engaging elements 5 are housed inside the large diameter cylindrical portion 72.

[0029] The large diameter cylindrical portion 72 has a pressed surface 77 on its inner peripheral surface. The pressed surface 77 is configured as a cylindrical surface centered on the central axis C. The input shaft 2 and the output shaft 3 are provided radially inward of the pressed surface 77. The large diameter cylindrical portion 72 has a second spigot fitting surface 78 on its outer peripheral surface on a first axial side. The second spigot fitting surface 78 is configured as a cylindrical surface centered on the central axis C. The second spigot fitting surface 78, the pressed surface 77, and the bearing receiving portion 74 of the small diameter cylindrical portion 71 are formed to be coaxial.

[0030] With the above-described configuration, the housing 4 is assembled by fitting the first spigot fitting surface 48 of the first housing 41 without rattle into the second spigot fitting surface 78 of the second housing 42. When the first housing 41 and the second housing 42 are assembled, the first axial end face of the large-diameter cylindrical portion 72 of the second housing 42 abuts against the end plate portion 45 of the first housing 41.

[0031] Furthermore, the first spigot fitting surface 48 and the bearing receiving portion 47 of the first housing 41 are arranged coaxially, and the second spigot fitting surface 78 and the bearing receiving portion 74 of the second housing 42 are arranged coaxially. Therefore, in an assembled state of the housing 4 where the first spigot fitting surface 48 and the second spigot fitting surface 78 are fitted together without any rattle, the bearing receiving portion 47 of the first housing 41 and the bearing receiving portion 74 of the second housing 42 are arranged coaxially.

[0032] 2 and 3, the pair of engaging elements 5 are semicircular and arranged radially inward of the housing 4. The pair of engaging elements 5 are configured to be movable toward and away from each other in the radial direction. Each of the pair of engaging elements 5 has a sliding surface 51 (sliding portion in claims), a bottom surface 52, an input side engaging portion (first engaging portion in claims) 53, and an output side engaging portion (second engaging portion in claims) 54.

[0033] The sliding surface 51 is a radially outer surface that is pressed against the pressed surface 77 and is an arc-shaped convex surface. The sliding surface 51 may be provided on a portion of the arc-shaped convex surface. The sliding surface 51 is in sliding contact with the pressed surface 77 when the reverse input cutoff clutch 1 is in a locked state (a state in which the reverse input from the output shaft 3 is cut off). The radial direction of the engaging element 5 refers to a direction perpendicular to the bottom surface 52, indicated by arrow A in FIG. 2 , and the direction parallel to the bottom surface 52, indicated by arrow B in FIG. 2 , may be referred to as the width direction of the engaging element 5. The radius of curvature of the sliding surface 51 is equal to or smaller than the radius of curvature of the pressed surface 77. Two sliding surfaces 51 are provided for each engaging element 5 (at two locations), and are formed to increase the frictional engagement force between the engaging element 5 and the pressed surface 77 due to a wedge effect. The two sliding surfaces 51 are provided at positions spaced apart from each other in the circumferential direction of the engaging element 5. The sliding surfaces 51 may be formed directly by the surfaces of the engaging elements 5, or may be formed to have a surface property with a higher coefficient of friction than other parts of the engaging elements 5. For example, the sliding surfaces 51 may be formed by a friction material fixed to the engaging elements 5 by adhesion or bonding. Each sliding surface 51 of the pair of engaging elements 5 faces radially outward from the housing 4.

[0034] The bottom surface 52 is located radially inward of the sliding surface 51. The bottom surface 52, together with the output-side engaging portion 54 of the engaging element 5 (described in detail below), forms a linear portion of the semicircular engaging element 5. The bottom surface 52 is a portion formed as a flat surface other than the portion where the output-side engaging portion 54 is formed. The bottom surfaces 52 of the pair of engaging elements 5 face each other in the radial direction. The pair of bottom surfaces 52 are formed to face each other across a gap when the engaging elements 5 are in an unlocked state (a state in which transmission of rotational force from the input shaft 2 to the output shaft 3 is permitted). The inner diameter dimension of the pressed surface 77 and the radial dimension of the engaging elements 5 are set so that, when the pair of engaging elements 5 are disposed radially inside the housing 4, a gap exists between the pressed surface 77 and the sliding surface 51 and / or between the pair of bottom surfaces 52. In this embodiment, the height of the bottom surface 52 in the radial direction (direction of arrow A) is slightly smaller than half the minor axis dimension of the insertion portion 32 of the output shaft 3 .

[0035] The input-side engaging portion 53 is a hole that penetrates a radially intermediate portion of the engaging element 5 in the axial direction. The input-side engaging portion 53 is a semicircular elongated hole that is long in the width direction. The arm portion 23 of the input shaft 2 engages with the input-side engaging portion 53. The input-side engaging portion 53 has a size that allows the arm portion 23 of the input shaft 2 to be loosely inserted therein. Specifically, when the arm portion 23 of the input shaft 2 is inserted inside the input-side engaging portion 53, gaps exist between the arm portion 23 and the inner surface of the input-side engaging portion 53 in both the width direction and the radial direction of the engaging element 5. Therefore, the arm portion 23 can be displaced relative to the input-side engaging portion 53 (engaging element 5) in the rotational direction of the input shaft 2, and the input-side engaging portion 53 can be displaced relative to the arm portion 23 in the radial direction of the engaging element 5.

[0036] The output-side engaging portion 54 is a linear portion of the semicircular engaging element 5 that extends from the center in the width direction to the intermediate portion in the width direction. The output-side engaging portion 54 is located radially inward of the input-side engaging portion 53. The output-side engaging portion 54 is located inward of the bottom surface 52 in the width direction B of the engaging element 5. The insertion portion 32 of the output shaft 3 engages with the output-side engaging portion 54. The output-side engaging portion 54 has a size and shape that allows both ends of the insertion portion 32 of the output shaft 3 in the minor axis direction to be positioned therein without rattle. Specifically, the opening width of the output-side engaging portion 54 in the direction of arrow B is larger than the dimension of the insertion portion 32 of the output shaft 3 in the major axis direction. The opening width of the output-side engaging portion 54 in the direction of arrow B may be formed to be equal to the dimension of the insertion portion 32 of the output shaft 3 in the major axis direction.

[0037] When the reverse input cutoff clutch 1 is assembled, the arm portion 23 of the input shaft 2 is axially inserted into each of the input side engaging portions 53 of the pair of engaging elements 5, and the insertion portion 32 of the output shaft 3 is axially inserted between the output side engaging portions 54 of the pair of engaging elements 5. In other words, the pair of engaging elements 5 are arranged so that the output side engaging portions 54 sandwich the insertion portion 32 of the output member from the radially outer side.

[0038] As shown in FIG. 3 , a metal sheet elastic member 11 may be provided between the pair of engaging elements 5. The elastic member 11 is disposed so as to be elastically sandwiched between the engaging element 5 and the output shaft 3. The elastic member 11 constantly biases the engaging element 5 radially outward, i.e., toward the pressed surface 77. End plates 13 may also be provided on both axial sides of the engaging element 5. These end plates 13 function, for example, as components for positioning each component in the axial direction, or components for preventing contact between the engaging element 5 and the output shaft 3 and input shaft 2 to suppress wear. In addition, a C-ring 12 or the like may be separately provided for positioning each component in the axial direction.

[0039] 1 , when the first housing 41, the second housing 42, and the engaging element 5 are assembled, the first spigot fitting surface 48 of the first housing 41 overlaps with at least a portion of the engaging element 5 in the axial direction. Specifically, the second axial end of the flange portion 44 of the first housing 41 is located closer to the second axial side than the first axial end of the engaging element 5. In other words, the first spigot fitting surface 48 of the first housing 41 is formed to have an axial engagement margin with the engaging element 5. In the present embodiment, the first spigot fitting surface 48 of the first housing 41 overlaps with the engaging element 5 by a length W in the axial direction.

[0040] 1, the plurality of bearing mechanisms include a first bearing mechanism 7 and a second bearing mechanism 8. In this embodiment, the first bearing mechanism 7 and the second bearing mechanism 8 are both ball bearings.

[0041] The first bearing mechanism 7 is provided between the input shaft 2 and the first housing 41 and rotatably holds the input shaft 2 relative to the first housing 41. The first bearing mechanism 7 includes balls (rolling elements) 60 that roll around the axis, an outer ring 61, an outer ring raceway groove 63 formed in the outer ring 61, and an inner ring raceway groove 67 integrally formed with the input shaft 2. The inner ring raceway groove 67 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 61 is attached to the bearing receiving portion 47 of the cylindrical portion 43 of the first housing 41 via a gap or the like. The outer ring raceway groove 63, along which the balls 60 roll, is formed in the inner peripheral surface of the outer ring 61. The input shaft 2 has an inner ring raceway groove 67 that contacts the balls 60 and along which the balls 60 roll. In other words, the first bearing mechanism 7 of this embodiment is formed without a separate member constituting an inner ring. A cage 14 that holds the balls 60 together may be provided. In addition, the first bearing mechanism 7 may be of a ball-loading type in which the balls 60 are assembled without deforming the outer ring 61.

[0042] The second bearing mechanism 8 is provided between the output shaft 3 and the second housing 42 and rotatably holds the output shaft 3 relative to the second housing 42. The second bearing mechanism 8 includes balls (rolling elements) 80 that roll around the shaft, an outer ring 81, an outer ring raceway groove 83 formed in the outer ring 81, and an inner ring raceway groove 87 integrally formed with the output shaft 3. The inner ring raceway groove 87 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 81 is attached to the bearing receiving portion 74 of the small-diameter cylindrical portion 71 of the second housing 42 via a gap or the like. The inner peripheral surface of the outer ring 81 is formed with an outer ring raceway groove 83 along which the balls 80 roll. The outer peripheral surface of the output shaft 3 is formed with an inner ring raceway groove 87 along which the balls 80 contact and roll. In other words, the second bearing mechanism 8 of this embodiment is formed without a separate member constituting an inner ring. Note that a cage 15 may be provided to hold the balls 80 together. As with the first bearing mechanism 7, the second bearing mechanism 8 of this embodiment may be of a ball-loading type in which the balls 80 are assembled without deforming the outer ring 81.

[0043] (Operation of the Reverse Input Disconnect Clutch) Next, the operation of the reverse input disconnect clutch 1 of this embodiment will be described. First, a case where a rotational force is input to the input shaft 2 from the input mechanism will be described. When a rotational force is input to the input shaft 2, as shown in FIG. 2 , the arm portion 23 of the input shaft 2 rotates around the central axis C inside the input-side engaging portion 53 in the rotational direction of the input shaft 2 (counterclockwise in the example shown in FIG. 2 ). Then, the corner portion (see point P1 in FIG. 2 ) between the flat portion 25 and the side portion 27 of the arm portion 23 presses the inner surface of the input-side engaging portion 53 radially inward, causing the pair of engaging elements 5 to move in a direction away from the pressed surface 77 (i.e., radially). In other words, the pair of engaging elements 5 move radially inward and closer to each other as the rotational force from the input shaft 2 acts on them via the input-side engaging portion 53. Specifically, the engaging element 5 located on the upper side of FIG. 2 moves downward, and the engaging element 5 located on the lower side of FIG. 2 moves upward. As a result, the bottom surfaces 52 of the pair of engaging pieces 5 move in directions approaching each other, and the pair of output side engaging portions 54 clamp the insertion portion 32 of the output shaft 3 from both radial sides.

[0044] As a result, the output shaft 3 is rotated so that the longitudinal axis direction of the insertion portion 32 is parallel to the bottom surfaces of the engagement elements 5, and the insertion portion 32 and the pair of output-side engagement portions 54 are engaged without rattle. Therefore, the rotational force input to the input shaft 2 is transmitted to the output shaft 3 via the pair of engagement elements 5 and output from the output shaft 3. When a rotational force is input to the input shaft 2, the reverse input cutoff clutch 1 of this embodiment moves the pair of engagement elements 5 in directions away from the pressed surface 77, regardless of the rotational direction of the input shaft 2. Then, regardless of the rotational direction of the input shaft 2, the rotational force input to the input shaft 2 is transmitted to the output shaft 3 via the pair of engagement elements 5.

[0045] Next, a case where a rotational force is input from the output mechanism to the output shaft 3 will be described. When a rotational force is input to the output shaft 3 in a reverse direction, as shown in FIG. 2 , the insertion portion 32 of the output shaft 3 rotates between the pair of output-side engaging portions 54 in the rotational direction of the output shaft 3 (counterclockwise in the example shown in FIG. 2 ). Then, the side surface 36 of the insertion portion 32 and the corner between the side surface 36 and the guide surface 37 (see point P2 in FIG. 2 ) press the output-side engaging portion 54 radially outward, causing the pair of engaging elements 5 to move toward the pressed surface 77. In other words, the pair of engaging elements 5 move radially outward and away from each other based on the engagement between the output shaft 3 and the output-side engaging portion 54. Specifically, the engaging element 5 located on the upper side in FIG. 2 moves upward, and the engaging element 5 located on the lower side in FIG. 2 moves downward. This causes the sliding surfaces 51 of the pair of engaging elements 5 to press against the pressed surface 77 of the housing 4. At this time, the sliding contact surface 51 and the pressed surface 77 are frictionally engaged over the entire range or at least a portion of the circumferential direction of the sliding contact surface 51 .

[0046] As a result, the rotational force input in reverse to the output shaft 3 is either completely blocked by being transmitted to the housing 4 fixed to another member not shown, and is not transmitted to the input shaft 2, or only a portion of the rotational force input in reverse to the output shaft 3 is transmitted to the input shaft 2, and the remainder is blocked.

[0047] In order to completely block the rotational force reversely input to the output shaft 3 and prevent it from being transmitted to the input shaft 2, the pair of engaging elements 5 are tensioned between the insertion portion 32 and the housing 4 so that the sliding surfaces 51 do not slide (rotate relative to) against the pressed surface 77, thereby locking the output shaft 3. On the other hand, in order to transmit only a portion of the rotational force reversely input to the output shaft 3 to the input shaft 2 and block the remainder, the pair of engaging elements 5 are tensioned between the insertion portion 32 and the housing 4 so that the sliding surfaces 51 slide against the pressed surface 77, thereby semi-locking the output shaft 3. When a rotational force is further reversely input to the output shaft 3 in the semi-locked state, the pair of engaging elements 5 rotate about the central axis C while sliding the sliding surfaces 51 against the pressed surface 77 based on the engagement between the insertion portion 32 of the output shaft 3 and the output-side engaging portion 54. When the pair of engaging members 5 rotate, the inner surface of the input side engaging portion 53 presses the radially inner surface of the arm portion 23 of the input shaft 2 in the circumferential direction (rotational direction), transmitting part of the rotational force to the input shaft 2.

[0048] In the reverse input cutoff clutch 1 of this embodiment, the size of the gap between each component is adjusted to enable the above-described operation. For example, when a rotational force is reversely input to the output shaft 3 and the sliding surface 51 of the engaging member 5 contacts the pressed surface 77 (locked state), the input shaft 2 is positioned in a neutral position. The neutral position of the input shaft 2 is a position where the flat surface 25 of the arm 23 is parallel to the input-side engaging portion 53. In other words, a gap is provided between the flat surface 25 of the arm 23 and the inner surface of the input-side engaging portion 53 that allows the sliding surface 51 to be pressed toward the pressed surface 77 when the corner (P2) of the insertion portion 32 of the output shaft 3 presses against the output-side engaging portion 54. This prevents the arm 23 from preventing the engaging member 5 from moving radially outward when a rotational force is reversely input to the output shaft 3. Furthermore, even after the sliding surface 51 comes into contact with the pressed surface 77, the surface pressure acting on the contact point between the sliding surface 51 and the pressed surface 77 changes depending on the magnitude of the rotational force input in reverse to the output shaft 3, thereby ensuring that the output shaft 3 is locked or semi-locked appropriately.

[0049] (Operations and Effects) The reverse input cutoff clutch 1 of this embodiment includes a housing 4, an input shaft 2, an output shaft 3, a pair of engaging elements 5, a first bearing mechanism 7, and a second bearing mechanism 8. The first bearing mechanism 7 has an inner ring raceway groove 67 formed integrally with the input shaft 2. The second bearing mechanism 8 has an inner ring raceway groove 87 formed integrally with the output shaft 3. This reduces the mating surfaces of the bearing mechanisms 7, 8 compared to when an inner ring is provided, thereby improving the coaxiality of the components connected via the bearing mechanisms 7, 8. Specifically, in this embodiment, the first bearing mechanism 7 improves the coaxiality of the input shaft 2 and the housing 4. Improving the coaxiality of the input shaft 2 and the housing 4 makes it easier to equalize the gaps between the pair of engaging elements 5 and the arms 23 of the input shaft 2. This allows the pair of arms 23 to press against the engaging elements 5 at the same time, preventing one arm 23 from pressing against the engaging element 5 first. This suppresses wear, vibration, and foreign matter contamination of parts, improving the performance of the reverse input cutoff clutch 1. Similarly, by providing the second bearing mechanism 8, the coaxiality of the output shaft 3 and the housing 4 can be improved. By improving the coaxiality of the output shaft 3 and the housing 4, it becomes easier to equalize the gap between the pair of engagement elements 5 and the pressed surface 77 of the housing 4. This suppresses deterioration of the locking function and bending of the output shaft 3, improving the performance of the reverse input cutoff clutch 1. Therefore, it is possible to provide a reverse input cutoff clutch 1 that can improve coaxiality and stabilize performance.

[0050] Furthermore, since there is no need to provide a separate member for the inner ring, the number of parts can be reduced, and the hardening process can also be eliminated. Also, since the raceway groove and the arm portion 23 of the input shaft 2 (or the insertion portion 32 in the case of the output shaft 3) can be machined in the same process using a single chuck, the coaxiality between each shaft and the housing 4 can be further improved.

[0051] The housing 4 has a first housing 41 and a second housing 42, which are spigot-jointed to each other. This spigot-jointing can improve the coaxiality of the first housing 41 and the second housing 42. As a result, the coaxiality of the input shaft 2 attached to the first housing 41 and the output shaft 3 attached to the second housing 42 can also be improved.

[0052] The inner peripheral surface of the first housing 41 forms the first spigot fitting surface 48, the outer peripheral surface of the second housing 42 forms the second spigot fitting surface 78 that is spigot-joined to the first spigot fitting surface 48, and a pressed surface 77 is provided on the inner peripheral surface of the second housing 42. By forming the outer peripheral surface of the housing 4 (the second housing 42 in this embodiment) as the spigot fitting surface, the radial outward opening of the opening of the second housing 42 is limited, and deformation of the housing 4 (the second housing 42) can be suppressed. This makes it possible to maintain coaxiality with high precision. Furthermore, the simple configuration consisting of two housings, the first housing 41 and the second housing 42, can suppress deformation of the pressed surface 77, thereby suppressing an increase in the radial outward movement of the pair of engaging elements 5 due to deformation and stabilizing the performance of the reverse input disconnect clutch 1.

[0053] The first spigot fitting surface 48 of the first housing 41 overlaps at least a portion of the engaging element 5 in the axial direction. By providing an axial engagement allowance on the first spigot fitting surface 48 with the engaging element 5, the deformation suppression effect of the pressed surface 77 of the second housing 42 can be further enhanced. Note that in the above-described embodiment, an example has been described in which the first spigot fitting surface 48 overlaps a portion of the engaging element 5 in the axial direction, but this is not limited to this. The first spigot fitting surface 48 may be provided to overlap the entire engaging element 5 in the axial direction. That is, the length W of the engagement allowance may be greater than the thickness of the engaging element 5. Similarly, as long as the first spigot fitting surface 48 at least overlaps with the engaging element 5 in the axial direction, the length W of the engagement allowance may be shorter than the length shown in FIG. 1 . However, since a larger engagement allowance can enhance the deformation suppression effect of the pressed surface 77, a larger engagement allowance is preferable.

[0054] In the above-described embodiment, for example, the second bearing mechanism 8 may be a bearing mechanism having an inner ring and an outer ring. That is, only the inner ring raceway groove 67 of the first bearing mechanism 7 may be integrally formed with the input shaft 2. Similarly, only the inner ring raceway groove 87 of the second bearing mechanism 8 may be integrally formed with the output shaft 3. Furthermore, in the present embodiment, each bearing mechanism 7, 8 has only the outer ring 61, 81, and the inner ring raceway groove 67, 87 is integrally formed with the input shaft 2 or the output shaft 3, but this is not limited to this. Each bearing mechanism 7, 8 may have only an inner ring, and the outer ring raceway groove 63, 83 is integrally formed with the first housing 41 or the second housing 42. That is, it is sufficient that at least one of the first bearing mechanism 7 and the second bearing mechanism 8 has at least one of the inner ring raceway groove 67, 87 and the outer ring raceway groove 63, 83 integrally formed with one of the input shaft 2, the output shaft 3, and the housing 4.

[0055] Next, second to eighth embodiments of the present invention will be described. In the following description, the same components as those in the first embodiment will be denoted by the same reference numerals and will not be described again. The specific configurations are not limited to these embodiments and can be modified as appropriate without departing from the spirit of the present invention. The components shown in the first to eighth embodiments can be configured in any suitable combination.

[0056] Second Embodiment A second embodiment of the present invention will now be described. Fig. 4 is a cross-sectional view of a reverse input cutoff clutch 201 according to the second embodiment. This embodiment differs from the first embodiment in that outer ring raceway grooves 263, 283 are further integrated with the housing 4 in the first bearing mechanism 207 and the second bearing mechanism 208.

[0057] In the second embodiment, the first bearing mechanism 207 has balls (rolling elements in the claims) 260 that roll around the axis, an outer ring raceway groove 263 formed integrally with the first housing 41, and an inner ring raceway groove 267 formed integrally with the input shaft 2. The outer ring raceway groove 263 and the inner ring raceway groove 267 are examples of raceway surfaces in the claims. The outer ring raceway groove 263, in which the balls 260 roll, is formed on the inner circumferential surface of the first housing 41. The inner ring raceway groove 267, in which the balls 260 roll, is formed on the outer circumferential surface of the input shaft 2. In other words, the first bearing mechanism 207 of this embodiment is formed without having separate members that constitute inner and outer rings.

[0058] The first bearing mechanism 207 of this embodiment is a ball-barrel type, in which the balls 260 are assembled without deforming the outer ring 61. Conventional ball bearings are formed by applying an external force to the outer ring, causing it to elastically deform into an elliptical shape, allowing for more balls to be packed in. In contrast, the ball-barrel type packs balls without deforming the outer ring. This reduces the number of balls packed in with the ball-barrel type compared to conventional ball bearings that deform the outer ring, but allows for balls to be packed in without deforming the outer ring. In this embodiment, the outer ring of the ball bearing is shared with the first housing 41, and the first housing 41 cannot be deformed. Therefore, by adopting the ball-barrel type, it is possible to form a ball bearing even when the first housing 41 serves as the outer ring of the ball bearing.

[0059] The second bearing mechanism 208 has balls (rolling elements in the claims) 280 that roll around the axis, an outer ring raceway groove 283 formed integrally with the second housing 42, and an inner ring raceway groove 287 formed integrally with the output shaft 3. The outer ring raceway groove 283 and the inner ring raceway groove 287 are examples of raceway surfaces in the claims. The outer ring raceway groove 283, in which the balls 280 roll, is formed on the inner peripheral surface of the second housing 42. The inner ring raceway groove 287, in which the balls 280 roll, is formed on the outer peripheral surface of the output shaft 3. In other words, the second bearing mechanism 208 of this embodiment is formed without having separate members that constitute inner and outer rings.

[0060] In this embodiment, the second housing 42 is formed, for example, by machining the second spigot fitting surface 78, the pressed surface 77, and the outer ring raceway groove 283 in the same process. Similarly, the first housing 41 is formed, for example, by machining the first spigot fitting surface 48 and the outer ring raceway groove 263 in the same process. This makes it possible to further improve the coaxiality of the second housing 42, the output shaft 3, the first housing 41, and the input shaft 2.

[0061] The first bearing mechanism 207 and the second bearing mechanism 208 are ball bearings with ball bearing specifications, which allows the above-mentioned bearing mechanisms to be realized without deforming the housing 4, which corresponds to the outer ring.

[0062] Third Embodiment A third embodiment of the present invention will be described. Fig. 5 is a cross-sectional view of a reverse input cutoff clutch 301 according to the third embodiment. This embodiment differs from the first embodiment in that the bearing mechanisms 307, 308 are tapered roller bearings. Note that in the third and subsequent embodiments, the cages between the rolling elements are not shown.

[0063] In the third embodiment, the first bearing mechanism 307 is a tapered roller bearing. The first bearing mechanism 307 includes a truncated conical roller (a rolling element in the claims) 360 that rolls around the axis, an outer ring 361, an outer ring raceway groove 363 formed in the outer ring 361, and an inner ring raceway groove 367 integrally formed with the input shaft 2. The inner ring raceway groove 367 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 361 is attached to the bearing receiving portion 47 of the cylindrical portion 43 of the first housing 41 by press-fitting or the like. The outer ring raceway groove 363, in which the roller 360 rolls, is formed in the inner peripheral surface of the outer ring 361. The inner ring raceway groove 367, in which the roller 360 rolls, is formed in the outer peripheral surface of the input shaft 2. In other words, the first bearing mechanism 307 of this embodiment is formed without a separate member constituting an inner ring.

[0064] The second bearing mechanism 308 is a tapered roller bearing. The second bearing mechanism 308 includes a truncated conical roller (a rolling element in the claims) 380 that rolls around the axis, an outer ring 381, an outer ring raceway groove 383 formed in the outer ring 381, and an inner ring raceway groove 387 integrally formed with the output shaft 3. The inner ring raceway groove 387 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 381 is attached to the bearing receiving portion 74 of the small-diameter cylindrical portion 71 of the second housing 42 by press-fitting or the like. The outer peripheral surface of the outer ring 381 is formed with an outer ring raceway groove 383 along which the roller 380 rolls. The outer peripheral surface of the output shaft 3 is formed with an inner ring raceway groove 387 along which the roller 380 rolls. In other words, the second bearing mechanism 308 of this embodiment is formed without a separate member constituting an inner ring.

[0065] (Fourth embodiment) A fourth embodiment of the present invention will be described. Fig. 6 is a cross-sectional view of a reverse input cutoff clutch 401 according to the fourth embodiment. This embodiment differs from the third embodiment in that outer ring raceway grooves 463, 483 are integrated with the input shaft 2 or the output shaft 3.

[0066] In the fourth embodiment, the first bearing mechanism 407 is a tapered roller bearing. The first bearing mechanism 407 includes a truncated conical roller (a rolling element in the claims) 460 that rolls around the axis, an outer ring raceway groove 463 integrally formed with the first housing 41, an inner ring 465, and an inner ring raceway groove 467 formed in the inner ring 465. The outer ring raceway groove 463 is an example of a raceway surface in the claims. The outer ring raceway groove 463, in which the roller 460 rolls, is formed on the inner peripheral surface of the first housing 41. The inner peripheral surface of the inner ring 465 is attached to the outer peripheral surface of the input shaft 2 by press-fitting or the like. The inner ring raceway groove 467, in which the roller 460 rolls, is formed on the outer peripheral surface of the inner ring 465. In other words, the first bearing mechanism 407 of this embodiment is formed without a separate member constituting an outer ring.

[0067] The second bearing mechanism 408 is a tapered roller bearing. The second bearing mechanism 408 includes a truncated conical roller (a rolling element in the claims) 480 that rolls around the axis, an outer ring raceway groove 483 integrally formed with the second housing 42, an inner ring 485, and an inner ring raceway groove 487 formed in the inner ring 485. The outer ring raceway groove 483 is an example of a raceway surface in the claims. The outer ring raceway groove 483, along which the roller 480 rolls, is formed on the inner peripheral surface of the second housing 42. The inner peripheral surface of the inner ring 485 is attached to the outer peripheral surface of the output shaft 3 by press-fitting or the like. The inner peripheral surface of the inner ring 485 is formed with an inner ring raceway groove 487, along which the roller 480 rolls. In other words, the second bearing mechanism 408 of this embodiment is formed without a separate member constituting an outer ring.

[0068] Fifth Embodiment A fifth embodiment of the present invention will now be described. Fig. 7 is a cross-sectional view of a reverse input cutoff clutch 501 according to the fifth embodiment. This embodiment differs from the fourth embodiment in that the flat inner ring raceway grooves 563, 583 in the first bearing mechanism 507 and the second bearing mechanism 508 are integrated with the housing 4.

[0069] In the fifth embodiment, the first bearing mechanism 507 is a tapered roller bearing. The first bearing mechanism 507 has a truncated conical roller (rolling element) 560 that rolls around the axis, an outer ring raceway groove 563 integrally formed with the first housing 41, and an inner ring raceway groove 567 integrally formed with the input shaft 2. The outer ring raceway groove 563 and the inner ring raceway groove 567 are examples of raceway surfaces in the claims. The outer ring raceway groove 563, in which the roller 560 rolls, is formed on the inner circumferential surface of the first housing 41. The inner ring raceway groove 567, in which the roller 560 rolls, is formed on the outer circumferential surface of the input shaft 2. In other words, the first bearing mechanism 507 of this embodiment is formed without separate components that constitute an inner ring and an outer ring.

[0070] The second bearing mechanism 508 is a tapered roller bearing. The second bearing mechanism 508 has a truncated conical roller (rolling element) 580 that rolls around the axis, an outer ring raceway groove 583 integrally formed with the second housing 42, and an inner ring raceway groove 587 integrally formed with the output shaft 3. The outer ring raceway groove 583 and the inner ring raceway groove 587 are examples of raceway surfaces in the claims. The outer ring raceway groove 583, in which the roller 580 rolls, is formed on the inner peripheral surface of the second housing 42. The inner ring raceway groove 587, in which the roller 580 rolls, is formed on the outer peripheral surface of the output shaft 3. In other words, the second bearing mechanism 508 of this embodiment is formed without having separate members that constitute an inner ring and an outer ring.

[0071] Sixth Embodiment A sixth embodiment of the present invention will now be described. Fig. 8 is a cross-sectional view of a reverse input cutoff clutch 601 according to the sixth embodiment. This embodiment differs from the first embodiment in that each of the bearing mechanisms 607, 608 is a cylindrical roller bearing.

[0072] In the sixth embodiment, the first bearing mechanism 607 is a cylindrical roller bearing. The first bearing mechanism 607 includes cylindrical rollers (rolling elements) 660 that roll around the axis, an outer ring 661, an outer ring raceway groove 663 formed in the outer ring 661, and an inner ring raceway groove 667 integrally formed with the input shaft 2. The inner ring raceway groove 667 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 661 is attached to the bearing receiving portion 47 of the cylindrical portion 43 of the first housing 41 by press-fitting or the like. The outer peripheral surface of the outer ring 661 is formed with an outer ring raceway groove 663 along which the rollers 660 roll. The outer peripheral surface of the input shaft 2 is formed with an inner ring raceway groove 667 along which the rollers 660 roll. In other words, the first bearing mechanism 607 of this embodiment is formed without a separate member constituting an inner ring.

[0073] The second bearing mechanism 608 is a cylindrical roller bearing. The second bearing mechanism 608 includes cylindrical rollers (rolling elements) 680 that roll around the axis, an outer ring 681, an outer ring raceway groove 683 formed in the outer ring 681, and an inner ring raceway groove 687 integrally formed with the output shaft 3. The inner ring raceway groove 687 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 681 is attached to the bearing receiving portion 74 of the small-diameter cylindrical portion 71 of the second housing 42 by press-fitting or the like. The outer peripheral surface of the outer ring 681 is formed with an outer ring raceway groove 683 along which the rollers 680 roll. The outer peripheral surface of the output shaft 3 is formed with an inner ring raceway groove 687 along which the rollers 680 roll. In other words, the second bearing mechanism 608 of this embodiment is formed without a separate member constituting an inner ring.

[0074] Seventh Embodiment A seventh embodiment of the present invention will now be described. Fig. 9 is a cross-sectional view of a reverse input cutoff clutch 701 according to the seventh embodiment. This embodiment differs from the first embodiment in that each of the bearing mechanisms 707, 708 is a needle roller bearing.

[0075] In the seventh embodiment, the first bearing mechanism 707 is a needle roller bearing. The first bearing mechanism 707 includes needle rollers (rolling elements) 760 that roll around the shaft, an outer ring 761, an outer ring raceway groove 763 formed in the outer ring 761, and an inner ring raceway surface 767 integrally formed with the input shaft 2. The inner ring raceway surface 767 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 761 is attached to the bearing receiving portion 47 of the cylindrical portion 43 of the first housing 41 by press fitting or the like. The outer peripheral surface of the outer ring 761 is formed with an outer ring raceway groove 763 along which the rollers 760 roll. The outer peripheral surface of the input shaft 2 is formed with an inner ring raceway surface 767 along which the rollers 760 roll. In other words, the first bearing mechanism 707 of this embodiment is formed without a separate member constituting an inner ring. The inner ring raceway surface 767 is the surface on which the rollers 760 roll, and may be provided flush with other outer peripheral surfaces of the input shaft 2, for example, or the surface properties of the portion on which the rollers 760 roll may be changed by coating or processing.

[0076] The second bearing mechanism 708 is a needle roller bearing. The second bearing mechanism 708 includes needle rollers (rolling elements) 780 that roll around the shaft, an outer ring 781, an outer ring raceway groove 783 formed in the outer ring 781, and an inner ring raceway surface 787 integrally formed with the output shaft 3. The inner ring raceway surface 787 is an example of a raceway surface in the claims. The outer peripheral surface of the outer ring 781 is attached to the bearing receiving portion 74 of the small-diameter cylindrical portion 71 of the second housing 42 by press-fitting or the like. The inner peripheral surface of the outer ring 781 is formed with an outer ring raceway groove 783 along which the rollers 780 roll. The outer peripheral surface of the output shaft 3 is formed with an inner ring raceway surface 787 along which the rollers 780 roll. In other words, the second bearing mechanism 708 of this embodiment is formed without a separate member constituting an inner ring.

[0077] Eighth Embodiment An eighth embodiment of the present invention will now be described. Fig. 10 is a cross-sectional view of a reverse input cutoff clutch 801 according to the eighth embodiment. This embodiment differs from the seventh embodiment in that outer ring raceway grooves 863, 883 are further integrated with the housing 4 in a first bearing mechanism 807 and a second bearing mechanism 808.

[0078] In the eighth embodiment, the first bearing mechanism 807 is a needle roller bearing. The first bearing mechanism 807 has needle rollers (rolling elements in the claims) 860 that roll around the axis, an outer ring raceway groove 863 integrally formed with the first housing 41, and an inner ring raceway surface 867 integrally formed with the input shaft 2. The outer ring raceway groove 863 and the inner ring raceway surface 867 are examples of raceway surfaces in the claims. The outer ring raceway groove 863 for the rollers 860 to roll on is formed on the inner peripheral surface of the first housing 41. The inner ring raceway surface 867 for the rollers 860 to roll on is formed on the outer peripheral surface of the input shaft 2. In other words, the first bearing mechanism 807 of this embodiment is formed without having separate members that constitute inner and outer rings.

[0079] The second bearing mechanism 808 is a needle roller bearing. The second bearing mechanism 808 has needle rollers (rolling elements in the claims) 880 that roll around the shaft, an outer ring raceway groove 883 integrally formed with the second housing 42, and an inner ring raceway surface 887 integrally formed with the output shaft 3. The outer ring raceway groove 883 and the inner ring raceway surface 887 are examples of raceway surfaces in the claims. The outer ring raceway groove 883 for the rollers 880 to roll on is formed on the inner peripheral surface of the second housing 42. The inner ring raceway surface 887 for the rollers 880 to roll on is formed on the outer peripheral surface of the output shaft 3. In other words, the second bearing mechanism 808 of this embodiment is formed without having separate members that constitute inner and outer rings.

[0080] According to the second to eighth embodiments, various types of bearings can be applied to the present invention, thereby improving the versatility of the reverse input cutoff clutches 1, 201, 301, 401, 501, 601, 701, and 801.

[0081] The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described first embodiment, the input shaft body 21, the base portion 22, and the arm portion 23 of the input shaft 2 are integrally formed, but this is not limiting. The input shaft 2 may be formed by combining multiple parts. Similarly, the output shaft body 31 and the insertion portion 32 of the output shaft 3 may be formed by combining separate members.

[0082] In 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 this is not limited to this. The above-described bearing mechanism may also be used in a link-type reverse input cutoff clutch that uses a link mechanism, which is a known technology, as a reverse input cutoff mechanism. The input shaft body 21 and the arm portion 23 may be configured as separate bodies. In addition to the above-described bearings, for example, deep groove ball bearings, angular contact ball bearings, four-point ball bearings, double-row ball bearings, etc. may also be used as the bearing mechanisms 7, 8, 207, 208, 307, 308, 407, 408, 507, 508, 607, 608, 707, 708, 807, 808.

[0083] DESCRIPTION OF SYMBOLS 1, 201, 301, 401, 501, 601, 701, 801 Reverse input cutoff clutch 2 Input shaft 3 Output shaft 4 Housing 5 Engagement element 7, 207, 307, 407, 507, 607, 707, 807 First bearing mechanism 8, 208, 308, 408, 508, 608, 708, 808 Second bearing mechanism 41 First housing 42 Second housing 48 First spigot fitting surface (spigot fitting surface) 51 Sliding surface (sliding portion) 53 Input side engaging portion (first engaging portion) 54 Output side engaging portion (second engaging portion) 78 Second spigot fitting surface (spigot fitting surface) 60, 80, 260, 280 Ball (rolling element) 360, 380, 460, 480, 560, 580, 660, 680, 760, 780, 860, 880 Rollers (rolling elements) 63, 263, 363, 463, 563, 663, 763, 863 Outer ring raceway groove (of first bearing mechanism) 67, 267, 367, 467, 567, 667 Inner ring raceway groove (of first bearing mechanism) 767, 867 Inner ring raceway surface (of first bearing mechanism) 83, 283, 383, 483, 583, 683, 783, 883 Outer ring raceway groove (of second bearing mechanism) 87, 287, 387, 487, 587, 687 Inner ring raceway groove (of second bearing mechanism) 787, 887 Inner ring raceway surface (of second bearing mechanism) 77 Pressed surface C Center axis

Claims

1. A housing having a pressed surface; an input shaft provided radially inward from the pressed surface; an output shaft provided radially inward from the pressed surface; and a pair of engaging elements that are movable relative to one another in the radial direction, each of the pair of engaging elements having a first engaging portion facing the input shaft, a second engaging portion facing the output shaft, and a sliding portion facing the pressed surface; when a rotational force is input to the input shaft, the pair of engaging elements move toward each other radially inward based on the engagement between the input shaft and the first engaging portion, and transmit the rotational force to the output shaft based on the engagement between the second engaging portion and the output shaft; when a rotational force is input in reverse to the output shaft, the pair of engaging elements move radially outward based on the engagement between the output shaft and the second engaging portion, and the pressed surface and the sliding portion frictionally engage, At least one of the input shaft, the output shaft, and the housing has a raceway surface that contacts a rolling element of at least one of a first bearing mechanism between the input shaft and the housing and a second bearing mechanism between the output shaft and the housing.

2. A reverse input cutoff clutch as described in claim 1, wherein the housing comprises a first housing that rotatably holds the input shaft, and a second housing that rotatably holds the output shaft, one of the first housing and the second housing has the pressed surface on its inner circumferential surface, and the first housing and the second housing are spigot-joined.

3. A reverse input cutoff clutch as set forth in claim 2, wherein the inner peripheral surface of the first housing is a spigot fitting surface, the outer peripheral surface of the second housing is a spigot fitting surface that is spigot-joined with the inner peripheral surface of the first housing, and the pressed surface is provided on the inner peripheral surface of the second housing.

4. The reverse input disconnecting clutch according to claim 3, wherein the spigot fitting surface of the first housing overlaps with at least a portion of the engagement element in the axial direction.

5. A reverse input cut-off clutch according to any one of claims 1 to 4, wherein the first bearing mechanism and the second bearing mechanism are ball bearings, and the first bearing mechanism and the second bearing mechanism, in which a raceway groove is integrally formed, have a ball bearing specification in which the balls are assembled without deforming the outer ring.

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