Reverse input blocking clutch

Abstract

The present invention provides a structure that can reduce the contact pressure between the input member and the engaging element, the contact pressure between the output member and the engaging element, or both, while suppressing increases in manufacturing costs. The structure comprises a pressed member 2 having a pressed surface 6, an input member 3, an output member 4, and an engaging element 5 arranged radially inward of the pressed surface 6, the engaging element 5 having a pressing surface 34 facing the pressed surface 6, an input-side engaged portion 35 that can engage with the input-side engaging portion 13 of the input member 3, and an output-side engaged portion 36 that can engage with the output-side engaging portion 21 of the output member 4, and is arranged to be movable in a first direction which is the near-far direction relative to the pressed surface 6, and has convex curved portions 37 and 38 on at least one of the input-side engaged portion 35 that engages with the input-side engaging portion 13 and the output-side engaged portion 36 that engages with the output-side engaging portion 21.

Description

Technical Field

[0001] The present disclosure relates to a reverse input blocking clutch that transmits the rotational torque input to an input member to an output member, while completely blocking the rotational torque reversely input to the output member from being transmitted to the input member or transmitting only a part of it to the input member and blocking the remaining part.

Background Art

[0002] The reverse input blocking clutch includes an input member connected to an input side mechanism such as a drive source and an output member connected to an output side mechanism such as a speed reduction mechanism, and transmits the rotational torque input to the input member to the output member, while having a function of completely blocking the rotational torque reversely input to the output member from being transmitted to the input member or transmitting only a part of it to the input member and blocking the remaining part.

[0003] The reverse input blocking clutch includes a locking type reverse input blocking clutch having a mechanism for preventing the rotation of the output member when a rotational torque is reversely input to the output member, and a free type reverse input blocking clutch having a mechanism for idling the output member when a rotational torque is input to the output member, depending on the difference in the mechanism for blocking the rotational torque reversely input to the output member. Which of the locking type reverse input blocking clutch and the free type reverse input blocking clutch to use is appropriately determined according to the use of the device incorporating the reverse input blocking clutch and the like.

[0004] In the lock-type reverse input blocking clutch described in International Publication No. 2019 / 026794, when rotational torque is input to an input member, the input-side engaging portion of the input member engages with the input-side engaged portion of the engaging element, causing the engaging element to move away from the pressed surface provided on the pressed member, and the output-side engaged portion of the engaging element engages with the output-side engaging portion of the output member, thereby transmitting the rotational torque input to the input member to the output member. On the other hand, when rotational torque is input in reverse to the output member, the output-side engaging portion engages with the output-side engaged portion, causing the engaging element to move towards the pressed surface, pressing the pressing surface against the pressed surface and frictionally engaging the pressing surface with the pressed surface.

[0005] International Publication No. 2023 / 085127 describes a locking reverse input shutoff clutch that can prevent the generation of peak torque when switching from a locked or semi-locked state to an unlocked or semi-unlocked state, thereby ensuring good torque transmission efficiency.

[0006] In this reverse input blocking clutch, as the output member rotates in a predetermined direction, the two pressing surfaces provided on the engaging element are pressed against the pressed surface provided on the pressed member, and as the input member rotates in the direction opposite to the predetermined direction, the input-side engaging portion provided on the input member and the input-side engaged portion provided on the engaging element are engaged. In this state, the distance between the contact point between the input-side engaging portion and the input-side engaged portion and the rotation center of the input member, with respect to a second direction perpendicular to both the first direction which is the radial direction of the engaging element and the rotation center of the input member, is smaller than the distance between the contact point between the output-side engaging portion provided on the output member and the output-side engaged portion of the engaging element and the rotation center of the output member, with respect to the second direction.

[0007] Furthermore, when a rotational torque is input in reverse to the output member, and the two pressing surfaces are in contact with the pressed surface, the contact portion between the output-side engaging portion and the output-side engaged portion is located closer to the center of rotation of the output member with respect to the first direction than the imaginary straight line connecting the contact portion between one of the two pressing surfaces and the pressed surface and the center of rotation of the output member.

[0008] Furthermore, International Publication No. 2023 / 085395 describes a lockable reverse input blocking clutch that can suppress rattle in the input components.

[0009] In this reverse input blocking clutch, as the output member rotates in a predetermined direction, the two pressing surfaces provided on the engaging element are pressed against the pressed surface provided on the pressed member, and as the input member rotates in the direction opposite to the predetermined direction, the input-side engaging portion provided on the input member and the input-side engaged portion provided on the engaging element are engaged. In this state, the distance between the contact point between the input-side engaging portion and the input-side engaged portion and the rotation center of the input member, with respect to a second direction perpendicular to both the first direction which is the radial direction of the engaging element and the rotation center of the input member, is greater than the distance between the contact point between the output-side engaging portion provided on the output member and the output-side engaged portion of the engaging element and the rotation center of the output member, with respect to the second direction.

[0010] Furthermore, when a rotational torque is input in reverse to the output member, and the two pressing surfaces are in contact with the pressed surface, the contact portion between the output-side engaging portion and the output-side engaged portion is located closer to the center of rotation of the output member with respect to the first direction than the imaginary straight line connecting the contact portion between one of the two pressing surfaces and the pressed surface and the center of rotation of the output member.

[0011] In the reverse input cutoff clutch described in International Publication No. 2023 / 085395, when rotational torque is transmitted from the input member to the output member, the pressing surface of the input member on the rear side in the rotational direction tends to be pressed against the pressed surface. Therefore, this reverse input cutoff clutch allows for smooth switching from an unlocked or partially unlocked state to a locked or partially locked state, that is, good locking performance can be ensured. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] International Publication No. 2019 / 026794 Brochure [Patent Document 2] International Publication No. 2023 / 085127 Brochure [Patent Document 3] International Publication No. 2023 / 085395 Brochure [Overview of the project] [Problems that the invention aims to solve]

[0013] In the reverse input shutoff clutch described in International Publication No. 2019 / 026794, International Publication No. 2023 / 085127, and International Publication No. 2023 / 085395, the portion of the input-side engaging portion that engages with the input-side engaged portion, and the portion of the output-side engaging portion that engages with the output-side engaged portion, are each constructed with a convex curved surface, thereby preventing excessive contact pressure at the contact points between the input-side engaging portion and the input-side engaged portion, and between the output-side engaging portion and the output-side engaged portion.

[0014] However, in order to provide convex curved surfaces on the input-side engaging portion of the input member, which is a shaft-shaped member, that engages with the input-side engaged portion, and on the output-side engaging portion of the output member, which is a shaft-shaped member, that engages with the output-side engaged portion, it is necessary to forge the metal material to form the approximate outer shape, and then form the convex curved surfaces by cutting. This may increase the manufacturing costs of the input member and the output member.

[0015] This disclosure aims to realize a reverse input shutoff clutch structure that can reduce the contact pressure at the contact points between the input member and the engaging element, the contact points between the output member and the engaging element, or both, while suppressing increases in manufacturing costs. [Means for solving the problem]

[0016] A reverse input blocking clutch according to one aspect of the present disclosure comprises a pressed member, an input member, an output member, and an engaging element.

[0017] The member to be pressed has a surface to be pressed on its inner circumferential surface.

[0018] The input member has an input-side engaging portion located radially inward of the pressed surface and is arranged coaxially with the pressed surface.

[0019] The output member has an output-side engaging portion that is located radially inward from the input-side engaging portion and is arranged coaxially with the pressed surface.

[0020] The engaging element has a pressing surface facing the pressed surface, an input-side engaged portion that can engage with the input-side engaging portion, and an output-side engaged portion that can engage with the output-side engaging portion, and is arranged to be movable in a first direction which is the near-far direction relative to the pressed surface.

[0021] When rotational torque is input to the input member, the engaging element moves in a direction away from the pressed surface with respect to the first direction based on the engagement of the input-side engaging portion with the input-side engaged portion. By engaging the output-side engaged portion with the output-side engaging portion, the rotational torque input to the input member is transmitted to the output member. On the other hand, when rotational torque is reversely input to the output member, based on the engagement of the output-side engaging portion with the output-side engaged portion, the pressing surface is pressed against the pressed surface to frictionally engage the pressing surface with the pressed surface.

[0022] Particularly, in the reverse-input blocking clutch according to one aspect of the present disclosure, the engaging element has a convex curved surface portion on at least one of a portion of the input-side engaged portion that engages with the input-side engaging portion and a portion of the output-side engaged portion that engages with the output-side engaging portion.

[0023] In the reverse-input blocking clutch according to one aspect of the present disclosure, the convex curved surface portion can be provided to be convex toward the input-side engaging portion on a portion of the input-side engaged portion that engages with the input-side engaging portion, and the input-side engaging portion can have a flat surface portion on a portion that engages with the input-side engaged portion.

[0024] In the reverse-input blocking clutch according to one aspect of the present disclosure, the outer peripheral surface of the input-side engaging portion can be composed of a partial cylindrical surface portion centered on the central axis of the input member and the flat surface portion.

[0025] In the reverse-input blocking clutch according to one aspect of the present disclosure, the convex curved surface portion can be provided to be convex toward the output-side engaging portion on a portion of the output-side engaged portion that engages with the output-side engaging portion, and the output-side engaging portion can have a flat surface portion on a portion that engages with the output-side engaged portion.

[0026] In the reverse-input blocking clutch according to one aspect of the present disclosure, the outer peripheral surface of the output-side engaging portion can be composed of a partial cylindrical surface portion centered on the central axis of the output member and the flat surface portion.

[0027] In a reverse input blocking clutch according to one aspect of the present disclosure, the convex curved surface portion can be provided at two positions on the radially inner surface of the input-side engaged portion, which faces radially outward in the first direction of the engager, and is separated from in a second direction that is perpendicular to both the first direction and the axial direction of the pressed surface.

[0028] In a reverse input shutoff clutch according to one aspect of the present disclosure, the input-side engaged portion may have a single partially cylindrical convex surface on its radially inner surface, and the convex curved surface may be provided at two positions on the convex surface that are spaced apart in the second direction.

[0029] In a reverse input shutoff clutch according to one aspect of the present disclosure, the input-side engaged portion may have a connecting surface portion that connects two of the convex curved surfaces and is composed of a flat surface perpendicular to the first direction.

[0030] In a reverse input blocking clutch according to one aspect of the present disclosure, the convex curved portion can be provided at two positions within the output-side engaged portion that are separated in a second direction perpendicular to both the first direction and the axial direction of the pressed surface.

[0031] In a reverse input shutoff clutch according to one aspect of the present disclosure, the output-side engaged portion can be composed of a single partial cylindrical surface, and the convex curved surface portion can be provided at two positions on the output-side engaged portion that are spaced apart in the second direction.

[0032] In a reverse input shutoff clutch according to one aspect of the present disclosure, the output-side engaged portion may have a connecting surface portion that connects two of the convex curved surfaces and is composed of a flat surface perpendicular to the first direction.

[0033] In a reverse input blocking clutch according to one aspect of the present disclosure, the engaging element may be a press-formed metal plate. [Effects of the Invention]

[0034] According to one aspect of the reverse input shutoff clutch of this disclosure, it is possible to keep the contact pressure between the input member and the engaging element, the contact pressure between the output member and the engaging element, or both, low while suppressing an increase in manufacturing costs. [Brief explanation of the drawing]

[0035] [Figure 1] Figure 1 is a cross-sectional view of a reverse input interruption clutch, a first example of an embodiment of the present disclosure. [Figure 2] Figure 2 is a cross-sectional view of XX in Figure 1. [Figure 3] Figure 3 is a cross-sectional view of Figure 1, showing the state in which rotational torque is applied to the input member, with the holding member and biasing member omitted. [Figure 4] Figure 4 is a cross-sectional view of Figure 1, showing the state in which rotational torque is input to the output member, with the holding member and biasing member omitted. [Figure 5] Figure 5 is a front view showing the engaging element of the reverse input blocking clutch in the first example. [Figure 6] Figure 6 is a front view showing the engaged element of a reverse input shutoff clutch in a second example of an embodiment of the present disclosure. [Figure 7] Figure 7 is a front view showing a reverse input blocking clutch engager of a third example of an embodiment of the present disclosure. [Figure 8] Figure 8 is a front view showing the engaging element of a reverse input shutoff clutch in a fourth example of an embodiment of the present disclosure. [Figure 9] Figure 9 is a front view showing the engaging element of a reverse input shutoff clutch in a fifth example of the embodiment of the present disclosure. [Modes for carrying out the invention]

[0036] [Example 1] A first example of the embodiment of this disclosure will be described with reference to Figures 1 to 5.

[0037] In the following description, unless otherwise specified, axial, radial, and circumferential directions refer to the axial, radial, and circumferential directions of the pressed surface 6. The axial, radial, and circumferential directions of the pressed surface 6 coincide with the axial, radial, and circumferential directions of the input member 3, and also coincide with the axial, radial, and circumferential directions of the output member 4. Furthermore, one axial side refers to the input member 3 side (right side in Figure 1), and the other axial side refers to the output member 4 side (left side in Figure 1).

[0038] The direction of the engaging element 5 or the pressing surface 34 of the engaging element 5 relative to the pressed surface 6 is defined as the first direction (up and down direction in Figures 2 to 4), and the direction perpendicular to both the axial direction of the pressed surface 6 and the first direction is defined as the second direction (left and right direction in Figures 2 to 4). For the engaging element 5, the direction coinciding with the first direction is defined as its radial direction (direction indicated by arrow α in Figure 3), and the direction coinciding with the second direction is defined as its width direction (direction indicated by arrow β in Figure 3).

[0039] <Explanation of the structure of the reverse input blocking clutch> The reverse input blocking clutch 1 comprises a pressed member 2, an input member 3, an output member 4, and an engaging element 5. The reverse input blocking clutch 1 transmits the rotational torque input to the input member 3 to the output member 4, while the reverse input blocking function either completely blocks the rotational torque that is reverse input to the output member 4 and does not transmit it to the input member 3, or transmits only a portion of it to the input member 3 and blocks the rest.

[0040] The member to be pressed 2 has a surface to be pressed 6 on its inner circumferential surface.

[0041] The pressed member 2 is supported and fixed to a part that does not rotate even when the reverse input blocking clutch 1 is in use, or it is integrally provided with the fixed part so that its rotation is restrained.

[0042] The pressed surface 6 constitutes the surface that contacts the pressing surface 34 of the engaging element 5 when the engaging element 5 moves radially outward, which is the direction towards the pressed surface 6. The shape of the pressed member 2 is not limited as long as it is configured to have the pressed surface 6 on its inner circumferential surface. The pressed surface 6 is annular when viewed from the axial direction, but is not limited to this, although in this example it has a cylindrical shape in which the inner diameter does not change with respect to the axial direction.

[0043] The input-side engaging portion 13 of the input member 3 and the output-side engaging portion 21 of the output member 4 are positioned radially inward of the pressed surface 6. The input-side engaging portion 13, the output-side engaging portion 21, and the engaging element 5 are rotatable radially inward of the pressed surface 6.

[0044] In this example, the pressed member 2 includes a housing element 7.

[0045] The housing element 7 has a stepped cylindrical inner surface. Specifically, the inner surface of the housing element 7 is formed by connecting a large-diameter cylindrical surface portion 8 on one axial side and a small-diameter cylindrical surface portion 9 on the other axial side with a connecting surface portion 10 facing one axial side. In this example, the large-diameter cylindrical surface portion 8 constitutes the pressed surface 6.

[0046] Furthermore, the housing element 7 has an inwardly projecting flange portion 11 at the other axial end of the small-diameter cylindrical surface portion 9, and has screw holes 12 opening at multiple locations in the circumferential direction on the side surface on the other axial side. The pressed member 2 in this example is supported and fixed to the fixing portion by screwing a bolt, which is inserted through a through hole provided in the fixing portion, into the screw holes 12.

[0047] The pressed member 2 may also include another housing element that closes the opening on one axial side of the housing element 7. In this case, the pressed member 2 is constructed by fitting the other housing element to the axial end of the housing element 7 without any play (spigot fitting), thereby positioning the housing element 7 and the other housing element radially, and then connecting the housing element 7 and the other housing element with a connecting member such as a bolt.

[0048] The input member 3 has an input-side engaging portion 13 located radially inward of the pressed surface 6 and is arranged coaxially with the pressed surface 6.

[0049] The input member 3 is connected to an input-side mechanism such as an electric motor, and rotational torque is input to it. Specifically, the input member 3 is composed of the output shaft of the input-side mechanism, or it is composed as a separate component from the output shaft and can be fixed coaxially to the output shaft. Additionally, the input shaft portion 14 provided on the input member 3 can be rotatably supported with respect to the fixed portion.

[0050] The input-side engaging portion 13 is provided on a part of the input member 3 that is radially outward from the center of rotation and has a portion that engages, specifically contacts, with the input-side engaged portion 35 of the engaging element 5. The input-side engaging portion 13 is configured to engage, i.e., contact, its radially inner surface 15 with the radially inner surface of the input-side engaged portion as the input member 3 or engaging element 5 rotates.

[0051] Furthermore, the input-side engaging portion 13 may have a flat surface portion 16 in the portion that engages with the input-side engaged portion 35. The flat surface portion 16 may be provided only in the portion of the radial inner surface 15 of the input-side engaging portion 13 that engages with the input-side engaged portion 35, or it may be provided on the entire radial inner surface 15 of the input-side engaging portion 13. In this example, the flat surface portion 16 is provided on the entire radial inner surface 15 of the input-side engaging portion 13.

[0052] The outer circumferential surface of the input-side engaging portion 13 can have any configuration as long as it has a portion that engages with the input-side engaged portion 35, but it is preferable that it is composed only of a flat surface portion 16 and a partially cylindrical surface portion 17 centered on the central axis of the input member 3.

[0053] In this example, the outer circumferential surface of the input-side engaging portion 13 consists only of a flat surface portion 16 provided on the radially inner surface 15 and a partially cylindrical surface portion 17 provided on the radially outer surface 18. That is, the input-side engaging portion 13 has an arc-shaped end face when viewed from the axial direction. The flat surface portion 16 and the partially cylindrical surface portion 17 are connected by a pointed edge portion 19. However, the flat surface portion 16 and the partially cylindrical surface portion 17 can also be connected by chamfered portions such as corner chamfers and rounded chamfers.

[0054] Therefore, when manufacturing the input member 3 having the input-side engaging portion 13, it is not necessary to perform machining on the connection between the radially inner surface 15 and the radially outer surface 18 of the input-side engaging portion 13. For example, the input member 3 can be manufactured by forging a metal material to form its outer shape, and then performing finishing processes such as grinding as needed. This reduces the manufacturing cost of the input member 3. However, the input member 3 can also be manufactured by machining a metal material, including cutting.

[0055] In this example, the input member 3 has an input shaft portion 14 and an input flange portion 20, in addition to the input-side engaging portion 13.

[0056] The input shaft portion 14 has a cylindrical shape.

[0057] The input flange portion 20 protrudes radially outward from the outer circumferential surface of the other axial end of the input shaft portion 14 along its entire circumference.

[0058] The input-side engaging portion 13 protrudes axially toward the other side from the portion of the input flange portion 20 that is radially outward from the center of rotation on the other axial side.

[0059] The number of input-side engaging portions 13 is determined according to the number of engaging elements 5. If the engaging element 5 is composed of multiple engaging elements 5, the input-side engaging portions 13 are also composed of multiple input-side engaging portions 13.

[0060] In the reverse input blocking clutch 1 of this example, the engaging element 5 is composed of two engaging elements 5. Therefore, the input-side engaging portion 13 is composed of two input-side engaging portions 13, corresponding to the number of engaging elements 5. The two input-side engaging portions 13 are positioned at two radially opposite locations on the other axial side of the input flange portion 20, and are spaced apart from each other with respect to the radial direction of the input member 3.

[0061] The input member 3 can be rotatably supported with respect to the pressed member 2 or the fixed portion. In this example, the input member 3 is rotatably supported inside the fixed portion by a radial bearing.

[0062] The output member 4 has an output-side engaging portion 21 that is located radially inward from the input-side engaging portion 13, and is arranged coaxially with the pressed surface 6. In other words, the output member 4 is also arranged coaxially with the input member 3.

[0063] The output member 4 is connected to an output-side mechanism such as a reduction gear mechanism, and is configured to output rotational torque to the output-side mechanism as it rotates. Specifically, the output member 4 can be made up of the input shaft of the output-side mechanism, or it can be made up as a separate member from the input shaft and fixed coaxially to the input shaft.

[0064] The output-side engaging portion 21 has a portion that engages with the output-side engaged portion 36 of the engaging element 5. This engaging portion is located radially inward from the input-side engaging portion 13 and radially outward from the central axis of the output member 4, and is positioned to engage with the output-side engaged portion 36 of the engaging element 5. The output-side engaging portion 21 is configured to engage, or rather come into contact with, the output-side engaged portion 36 as the output member 4 or the engaging element 5 rotates.

[0065] The output-side engaging portion 21 has a cam function. The distance from the rotational axis of the output member 4 to the outer circumferential surface of the output-side engaging portion 21, which is the part that engages with the output-side engaged portion 36, is not constant in the circumferential direction.

[0066] The number of parts of the output-side engaging portion 21 that engage with the output-side engaged portion 36 is determined according to the number of engaging elements 5. If the engaging element 5 is composed of multiple engaging elements 5, the output-side engaging portion 21 is also configured to have multiple engaging parts. In this example, the output-side engaging portion 21 is configured to have two parts that engage with the output-side engaged portion 36, corresponding to the number of engaging elements 5. However, even if there is only one engaging element 5, it is possible to adopt a structure similar to this example.

[0067] The output-side engaging portion 21 may have a flat surface portion 22 in the part that engages with the output-side engaged portion 36. In this example, the output-side engaging portion 21 has a flat surface portion 22 in the part of its outer circumferential surface that faces the output-side engaged portion 36.

[0068] The outer circumferential surface of the output-side engaging portion 21 can be configured in any way as long as the output-side engaging portion 21 has a cam function, but it is preferable that it is composed of a flat surface portion 22 and a partially cylindrical surface portion 23 centered on the central axis of the output member 4.

[0069] In this example, the outer surface of the output-side engaging portion 21 is composed of two parallel flat surfaces 22 and two partially cylindrical surfaces 23. The output-side engaging portion 21 is symmetrical with respect to a virtual plane that passes through the rotational axis of the output member 4 and is perpendicular to the two flat surfaces 22. Furthermore, the output-side engaging portion 21 is symmetrical with respect to a virtual plane that passes through the rotational axis of the output member 4 and is parallel to the two flat surfaces 22. In other words, the output-side engaging portion 21 has a shape that is twice symmetrical with respect to the central axis of the output member 4. The flat surfaces 22 and the partially cylindrical surfaces 23 are connected by pointed edges 24. However, the flat surfaces 22 and the partially cylindrical surfaces 23 can also be connected by chamfered portions such as corner chamfers and rounded chamfers.

[0070] Therefore, when manufacturing the output member 4 having the output-side engaging portion 21, it is not necessary to perform machining on the portion of the output-side engaging portion 21 that engages with the output-side engaged portion 36. For example, the output member 4 can be manufactured by forging a metal material to form its outer shape, and then performing finishing processes such as grinding as needed. This reduces the manufacturing cost of the output member 4. However, the output member 4 can also be manufactured by machining a metal material, including cutting.

[0071] The output-side engaging portion 21 is located radially inside the two input-side engaging portions 13, and is positioned between the output-side engaged portions 36 of the two engaging elements 5.

[0072] In this example, the output member 4 has an output side engaging portion 21, as well as an output shaft portion 25, an output flange portion 26, and a small diameter shaft portion 27.

[0073] The output shaft portion 25 has a stepped cylindrical shape.

[0074] The output flange portion 26 protrudes radially outward from the outer circumferential surface of one axial end of the output shaft portion 25 along its entire circumference.

[0075] The output-side engaging portion 21 protrudes from the center of the end face on one axial side of the output shaft portion 25 toward the axial side.

[0076] The small-diameter shaft portion 27 has a cylindrical shape and protrudes from the center of the axial end face of the output-side engaging portion 21 toward the axial direction

[0077] The output member 4 can be rotatably supported by the pressed member 2 or the fixed portion. In this example, the output member 4 is rotatably supported radially inward of the housing element 7 of the pressed member 2 by a radial rolling bearing 28. The outer ring 29 of the radial rolling bearing 28 is fitted snugly into the small-diameter cylindrical surface portion 9 of the housing element 7 and is axially clamped between one axial side surface of the inward flange portion 11 and a retaining ring 30a that is locked to one axial end of the small-diameter cylindrical surface portion 9. The inner ring 31 of the radial rolling bearing 28 is fitted snugly onto one axial end of the output shaft portion 25 and is axially clamped between the other axial side surface of the output flange portion 26 and a retaining ring 30b that is locked to the outer circumferential surface of the axial intermediate portion of the output shaft portion 25.

[0078] In the illustrated example, the radial rolling bearing 28 is a ball bearing using balls as rolling elements 32. However, the radial rolling bearing for supporting the output member 4 can also be constructed using a tapered roller bearing with tapered rollers as rolling elements or a roller bearing with cylindrical rollers.

[0079] Furthermore, the small-diameter shaft portion 27 of the output member 4 is supported by a sliding bearing (also called a "sleeve bearing") 33 inside the input member 3, allowing for free relative rotation with respect to the input member 3.

[0080] The engaging element 5 has a pressing surface 34 facing the pressed surface 6, an input-side engaged portion 35 that can engage with the input-side engaging portion 13, and an output-side engaged portion 36 that can engage with the output-side engaging portion 21, and is arranged to allow movement of the engaging element 5 in the radial direction (= first direction).

[0081] When rotational torque is input to the input member 3, the engaging element 5 moves radially away from the pressed surface 6 based on the input-side engaging portion 13 engaging with the input-side engaged portion 35, and transmits the rotational torque input to the input member 3 to the output member 4 by engaging the output-side engaged portion 36 with the output-side engaging portion 21. Conversely, when rotational torque is input in reverse to the output member 4, the engaging element 5 presses the pressing surface 34 against the pressed surface 6 based on the output-side engaging portion 21 engaging with the output-side engaged portion 36, thereby frictionally engaging the pressing surface 34 with the pressed surface 6.

[0082] The engaging element 5 has convex curved surfaces 37 and 38 on at least one of the parts of the input-side engaged portion 35 that engages with the input-side engaging portion 13, and the output-side engaged portion 36 that engages with the output-side engaging portion 21.

[0083] In other words, the engaging element 5 may have a convex curved surface portion 37 on the part of the input-side engaged portion 35 that engages with the input-side engaging portion 13. Each input-side engaged portion 35 has a portion that engages with two input-side engaging portions 13. Therefore, the convex curved surface portion 37 is provided at two locations on the input-side engaged portion 35.

[0084] Additionally or alternatively, the engaging element 5 may have a convex curved surface portion 38 on the portion of the output-side engaged portion 36 that engages with the output-side engaging portion 21. Each output-side engaged portion 36 has portions that engage with two output-side engaging portions 21. Therefore, the convex curved surface portion 38 is provided at two locations on the output-side engaged portion 36.

[0085] In this example, the engaging element 5 has a convex curved surface portion 37 in the portion of the input-side engaged portion 35 that engages with the input-side engaging portion 13, and a convex curved surface portion 38 in the portion of the output-side engaged portion 36 that engages with the output-side engaging portion 21. Therefore, with the reverse input shutoff clutch 1 of this example, the contact pressure at the contact points between both the input member 3 and the output member 4 and the engaging element 5 can be kept low.

[0086] The pressing surface 34 is provided on the radially outer surface of the engaging element 5 facing the surface to be pressed 6. In this example, the pressing surface 34 is composed of two pressing surfaces 34 provided at two positions on the radially outer surface of the engaging element 5 that are spaced apart from each other in the circumferential direction. Each pressing surface 34 is composed of a partially cylindrical convex curved surface having a radius of curvature smaller than the radius of curvature of the surface to be pressed 6.

[0087] Of the radially outer surface of the engaging element 5, the portion that is circumferentially away from the two pressing surfaces 34 is located radially inward from a virtual circle that is centered on the central axis of the input member 3 and tangent to the two pressing surfaces 34, when viewed from the axial direction. In other words, when the two pressing surfaces 34 are in contact with the surface to be pressed 6, the portion that is circumferentially away from the two pressing surfaces 34 does not come into contact with the surface to be pressed 6.

[0088] The pressing surface 34 preferably has a surface property that results in a higher coefficient of friction with respect to the pressed surface 6 than the other parts of the engaging element 5. Furthermore, the pressing surface 34 can be integrally formed with the other parts of the engaging element 5, or it can be formed from the surface of a friction material fixed to the other parts of the engaging element 5 by means of adhesion or bonding.

[0089] In this example, the input-side engaged portion 35 is provided in the radial (=first direction) intermediate portion of the widthwise center of the engaging element 5. More specifically, although not limited to this, the input-side engaged portion 35 has a substantially arc-shaped opening when viewed from the axial direction and is composed of a through hole that penetrates the radial intermediate portion of the widthwise (=second direction) center of the engaging element 5 in the axial direction.

[0090] The input-side engaged portion 35 is sized to allow the input-side engaged portion 13 to be loosely inserted. Therefore, when the input-side engaged portion 13 is inserted inside the input-side engaged portion 35, there are gaps between the input-side engaged portion 13 and the inner surface of the input-side engaged portion 35 in the width direction and the radial direction of the engaging element 5. As a result, the input-side engaged portion 13 can be displaced relative to the input-side engaged portion 35 in the rotational direction of the input member 3, and the input-side engaged portion 35 can be displaced relative to the input-side engaged portion 13 in the radial direction (=first direction) of the engaging element 5.

[0091] The convex curved surface portion 37 is provided on the radially inner surface 39 of the inner surface of the input-side engaged portion 35, which faces radially outward (=first direction), in the portion that engages with the input-side engaged portion 13, so as to be convex toward the input-side engaged portion 13. The convex curved surface portion 37 is provided at two locations on the radially inner surface 39: the portion that engages with the input-side engaged portion 13 when the input member 3 rotates to one side relative to the engager 5, and the portion that engages with the input-side engaged portion 13 when the input member 3 rotates to the other side relative to the engager 5.

[0092] Specifically, the input-side engaged portion 35 has a convex portion 40 in the middle of the radial inner surface 39 in the width direction (= second direction) that protrudes radially outward from the adjacent portions on both sides in the width direction, and two convex curved portions 37 are provided at two positions in the width direction of the convex portion 40.

[0093] In this example, the convex curved surface portion 37 is provided at both ends of the convex curved surface portion 40 in the width direction. Furthermore, the convex curved surface portion 40 has a connecting surface portion 50 in the width direction intermediate between the two convex curved surface portions 37, which connects the two convex curved surface portions 37 and is composed of a flat surface perpendicular to the radial direction.

[0094] The cross-sectional shape and radius of curvature of the convex curved surface portion 37 are not particularly limited, as long as they can prevent the contact pressure at the contact point with the input-side engaging portion 13 from becoming excessive. For example, the cross-sectional shape of the convex curved surface portion 37 can be approximately arc-shaped, approximately elliptical, etc. The cross-sectional shape and radius of curvature of the convex curved surface portion 37 can be determined by experiment, simulation, etc.

[0095] In this example, the radially outer surface 41 of the inner surface of the input-side engaged portion 35, which faces radially inward, is composed of a curved surface having a substantially arc-shaped contour or a composite surface having a substantially V-shaped contour when viewed from the axial direction. The circumferential surface 42 connecting the radially inner surface 39 and the radially outer surface 41 is composed of a partially cylindrical concave curved surface.

[0096] The output-side engaged portion 36 is provided at the center of the width direction (=second direction) of the radially (=first direction) inner surface of the engaging element 5. The shape of the output-side engaged portion 36 is not limited as long as it is configured to engage with the output-side engaged portion 21. In this example, the output-side engaged portion 36 is provided at the center of the width direction of the radially inner surface of the engaging element 5, so as to protrude radially inward from the portions adjacent to it on both sides in the width direction.

[0097] The convex curved portion 38 is provided at two locations within the output-side engaging portion 36: the portion that engages with the output-side engaging portion 21 when the output member 4 rotates to one side, and the portion that engages with the output-side engaging portion 21 when the output member 4 rotates to the other side relative to the engaging element 5. The convex curved portion 38 is provided so as to be convex toward the output-side engaging portion 21.

[0098] In this example, the convex curved surface portion 38 is provided at both ends of the output-side engaged portion 36 in the width direction (= second direction). The output-side engaged portion 36 also has a connecting surface portion 51 in the width direction intermediate between the two convex curved surface portions 38, which connects the two convex curved surface portions 38 and is composed of a flat surface perpendicular to the radial direction.

[0099] The cross-sectional shape and radius of curvature of the convex curved surface portion 38 are not particularly limited, as long as they can prevent the contact pressure at the contact point with the output-side engaging portion 21 from becoming excessive. For example, the cross-sectional shape of the convex curved surface portion 38 can be approximately arc-shaped, approximately elliptical, etc. The cross-sectional shape and radius of curvature of the convex curved surface portion 38 can be determined by experiment, simulation, etc.

[0100] The method for manufacturing the engaging element 5 is not particularly limited and can be manufactured by any method. For example, the engaging element 5 can be manufactured by pressing a metal plate. Alternatively, the engaging element 5 can be manufactured by sintering, forging, casting, cutting, or a combination thereof on a metal material.

[0101] In this example, the engaging element 5 is manufactured by punching out a metal plate using a press. In other words, the engaging element 5 is a press-formed product of a metal plate.

[0102] In this example, the engaging element 5 is provided with convex curved surfaces 37 and 38 to reduce the contact pressure at the contact points between the input member 3 and the output member 4 and the engaging element 5. Therefore, compared to the case where the convex curved surfaces are provided by machining the contact points of the input member 3 and the output member 4 with the engaging element 5, manufacturing costs can be reduced.

[0103] In this example, the distance in the width direction (=second direction) of the engaging element 5 among the two convex curved surfaces 37 provided on the input-side engaged portion 35 is greater than the distance in the width direction (=second direction) of the engaging element 5 among the two convex curved surfaces 38 provided on the output-side engaged portion 36. Therefore, as the output member 4 rotates in a predetermined direction, the two pressing surfaces 34 are pressed against the pressed surface 6, and as the input member 3 rotates in the opposite direction to the predetermined direction, the input-side engaging portion 13 and the input-side engaged portion 35 are engaged. In this state, the distance between the contact point between the input-side engaging portion 13 and the convex curved surface 37 of the input-side engaged portion 35 and the center of rotation of the input member 3, in the width direction (=second direction) of the engaging element 5, is greater than the distance between the contact point between the output-side engaging portion 21 and the convex curved surface 38 of the output-side engaged portion 36 and the center of rotation of the output member 4, in the width direction (=second direction) of the engaging element 5.

[0104] Furthermore, in this example, when rotational torque is input in reverse to the output member 4, and the two pressing surfaces 34 are in contact with the pressed surface 6, the contact point between the output-side engaging portion 21 and the output-side engaged portion 36 (convex curved surface portion 38) is located on the side closer to the rotation center of the output member 4 in the radial direction (=first direction) of the engaging portion 5 than the imaginary straight line connecting the contact point between the pressing surface 34 of the two pressing surfaces 34 (the side closer to the contact point between the output-side engaging portion 21 and the output-side engaged portion 36 than the rotation center of the output member 4 in the width direction (=second direction) of the engaging portion 5) and the pressed surface 6, and the rotation center of the output member 4.

[0105] Therefore, the reverse input blocking clutch 1 in this example can ensure good locking performance for the same reasons as the reverse input blocking clutch described in International Publication No. 2023 / 085395.

[0106] The reverse input blocking clutch 1 in this example further comprises, as optional components, a biasing member 43 and a holding member 44.

[0107] The biasing member 43 elastically biases the engaging element 5 toward the pressed surface 6. The biasing member 43 can be made of a spring such as a leaf spring, coil spring, or disc spring, or an elastic material such as rubber, elastomer, or synthetic resin. The number of biasing members 43 is not particularly limited and is appropriately determined according to the number of engaging elements 5.

[0108] In this example, the biasing member 43 is composed of two biasing members 43 positioned at two locations in the width direction between the radially inner surfaces of the two engaging elements 5, and each biasing member 43 is composed of a compression coil spring. Each biasing member 43 is fitted and held in the holding hole 47 of the holding member 44, thereby preventing it from falling out from the portion between the two engaging elements 5.

[0109] The two biasing members 43 elastically bias the two engaging elements 5 toward the pressed surface 6 by the force that attempts to restore their elasticity. As a result, in the neutral state where no torque is applied to either the input member 3 or the output member 4, the pressing surfaces 34 of the two engaging elements 5 come into contact with the pressed surface 6.

[0110] The retaining member 44 comprises a first spacer portion 45 and a second spacer portion 46 arranged spaced apart in the axial direction, and two connecting portions 48 arranged on both sides of the first spacer portion 45 and the second spacer portion 46 with respect to a second direction, each connecting the first spacer portion 45 and the second spacer portion 46, and each having a retaining hole 47 extending in the first direction.

[0111] The retaining member 44 is attached to the output member 4 with the engaging element 5 positioned between the first spacer portion 45 and the second spacer portion 46 in the axial direction, thereby restricting the axial movement of the engaging element 5 relative to the output member 4. Specifically, the retaining ring 49, which is locked to the small-diameter shaft portion 27 of the output member 4, restricts the movement of the retaining member 44 to one side in the axial direction, and the other side of the second spacer portion 46 is brought into contact with or close to the end face of the output shaft portion 25 on one side in the axial direction, thereby restricting the movement of the retaining member 44 to the other side in the axial direction.

[0112] <Explanation of the operation of the reverse input blocking clutch> The operation of the reverse input blocking clutch 1 in this example will be explained using Figures 3 and 4. Note that Figures 3 and 4 omit the biasing member 43 and the holding member 44, and exaggerate the radial gap between the input member 3 and the output member 4 and the two engaging elements 5.

[0113] When rotational torque is applied to the input member 3, the two engaging elements 5 move away from the pressed surface 6, regardless of the rotation direction of the input member 3. More specifically, as shown in Figure 3, the input-side engaging portion 13 rotates inside the input-side engaged portion 35 in the direction of rotation of the input member 3 (counterclockwise in the example of Figure 3).

[0114] This reduces the gap between the radially inner surface 15 of the input-side engaging portion 13 and the radially inner surface 39 of the input-side engaged portion 35, causing the radially inner surface 15 of the input-side engaging portion 13 to come into contact with the radially inner surface 39 of the input-side engaged portion 35.

[0115] In this example, the radially inner surface 15 of the input-side engaging portion 13 is brought into contact with one of the two convex curved surfaces 37 provided on the input-side engaged portion 35.

[0116] From this state, as the input member 3 rotates further, the radially inner surface 15 of the input-side engaging portion 13 presses one of the convex curved portions 37 radially inward, causing the engaging element 5 to move away from the pressed surface 6. That is, the two engaging elements 5 move radially inward, moving closer to each other based on their engagement with the input member 3, so that the radially inner surfaces of the two engaging elements 5 come closer to each other, and the output-side engaged portions 36 of the two engaging elements 5 clamp the output-side engaging portion 21 of the output member 4 from both radial sides.

[0117] In this way, the output member 4 is rotated so that the flat surface portion 22 of the output-side engaging portion 21 is parallel to the connecting surface portion 51 of the output-side engaged portion 36, while the output-side engaging portion 21 and the output-side engaged portion 36 of the engaging element 5 are engaged without any rattle. As a result, the rotational torque input to the input member 3 is transmitted to the output member 4 via the two engaging elements 5 and output from the output member 4.

[0118] When rotational torque is applied in reverse to the output member 4, the two engaging elements 5 move toward the pressed surface 6, regardless of the rotation direction of the output member 4. Specifically, as shown in Figure 4, the output-side engaging portion 21 rotates in the direction of rotation of the output member 4 (clockwise in the example of Figure 4) inside the output-side engaged portions 36 of the two engaging elements 5. The flat surface portion 22 of the outer circumferential surface of the output-side engaging portion 21 presses the output-side engaged portions 36 radially outward, causing the two engaging elements 5 to move toward the pressed surface 6.

[0119] In other words, the two engaging elements 5 move radially outward, away from each other, based on their engagement with the output member 4, so that the pressing surfaces 34 of the two engaging elements 5 come into contact with the pressed surface 6 and frictionally engage with the pressed surface 6.

[0120] As a result, the rotational torque reversed into the output member 4 is either completely blocked and not transmitted to the input member 3, or only a portion of the rotational torque reversed into the output member 4 is transmitted to the input member 3 and the rest is blocked.

[0121] In order to completely block the rotational torque that is reverse-input to the output member 4 and prevent it from being transmitted to the input member 3, the pressing surface 34 of the engaging element 5 slides against the pressed surface 6, and the engaging element 5 is braced or clamped between the output-side engaging part 21 and the pressed member 2 so that the engaging element 5 and the pressed member 2 do not rotate relative to each other, thereby locking the output member 4.

[0122] To ensure that only a portion of the rotational torque inverted to the output member 4 is transmitted to the input member 3 and the remainder is blocked, the engaging element 5 is braced or clamped between the output-side engaging part 21 and the pressed member 2 so that the pressing surface 34 of the engaging element 5 slides against the pressed surface 6, thereby partially locking the output member 4.

[0123] In the reverse input blocking clutch 1 of this example, the size of the gaps between each component is adjusted so that the above operation is possible. In particular, when the pressing surfaces 34 of the two engaging elements 5 are in contact with the pressed surface 6, a gap exists between the radially inner surface 15 of the input-side engaging portion 13 and the convex portion 40 of the input-side engaged portion 35.

[0124] This prevents the radial outward movement of the engaging element 5 from being blocked by the input-side engaging part 13 when rotational torque is input in reverse to the output member 4, and also ensures that even after the pressing surface 34 contacts the pressed surface 6, the surface pressure acting on the contact area between the pressing surface 34 and the pressed surface 6 changes according to the magnitude of the rotational torque input in reverse to the output member 4, thereby ensuring that the output member 4 is properly locked or partially locked.

[0125] [Example 2] A second example of the embodiment of this disclosure will be described with reference to Figure 6.

[0126] In this example, the width dimension of the convex portion 40a provided in the middle of the width direction (=second direction) of the engagement 5a on the radial (=first direction) inner surface of the input-side engaged portion 35 is smaller than the width dimension of the convex portion 40 of the engagement 5 in the first example. When such an engaging element 5a is incorporated into the reverse input blocking clutch 1, as the output member 4 rotates in a predetermined direction, the two pressing surfaces 34 are pressed against the pressed surface 6, and as the input member 3 rotates in the opposite direction to the predetermined direction, the input-side engaging portion 13 and the input-side engaged portion 35 are engaged. In this state, the distance between the contact point between the input-side engaging portion 13 and the convex curved surface portion 37 of the input-side engaged portion 35 and the rotation center of the input member 3, with respect to the width direction (= second direction) of the engaging element 5a, is smaller than the distance between the contact point between the output-side engaging portion 21 and the convex curved surface portion 38 of the output-side engaged portion 36 and the rotation center of the output member 4, with respect to the width direction (= second direction) of the engaging element 5a.

[0127] Therefore, the reverse input blocking clutch 1 incorporating the engaging element 5a of this example can ensure good torque transmission efficiency for the same reasons as the reverse input blocking clutch described in International Publication No. 2023 / 085217.

[0128] The composition and effects of the other parts of the second example are the same as those of the first example.

[0129] [Example 3] A third example of the embodiment of this disclosure will be described with reference to Figure 7.

[0130] In this example, the engaging element 5b has a convex curved surface portion 38 in the portion of the output-side engaged portion 36 that engages with the output-side engaging portion 21, whereas the portion of the input-side engaged portion 35 that engages with the input-side engaging portion 13 does not have a convex curved surface portion. Specifically, the entire radial inner surface 39a of the input-side engaged portion 35, including the portion that engages with the input-side engaging portion 13, is composed of a flat surface perpendicular to the radial direction (=first direction) of the engaging element 5b.

[0131] Therefore, when the engaging element 5b is incorporated into the reverse input blocking clutch 1, it is preferable to provide a convex curved surface portion in the portion of the input-side engaging portion 13 of the input member 3 that engages with the input-side engaged portion 35.

[0132] In this example, a convex curved surface portion 38 is provided on the engaging element 5b to reduce the contact pressure at the contact point between the output member 4 and the engaging element 5b. Therefore, compared to the case where the convex curved surface portion is provided on the contact point of the output member 4 with the engaging element 5b by machining, manufacturing costs can be reduced.

[0133] The composition and effects of the other parts of the third example are the same as those of the first example.

[0134] [Example 4] A fourth example of the embodiments of this disclosure will be described with reference to Figure 8.

[0135] In this example, the engaging element 5c has a convex curved surface portion 37 in the portion of the input-side engaged portion 35 that engages with the input-side engaging portion 13, whereas the portion of the output-side engaged portion 36a that engages with the output-side engaging portion 21 does not have a convex curved surface portion. Specifically, the entire radially inner surface of the engaging element 5c, including the output-side engaged portion 36a, is composed of a flat surface perpendicular to the radial direction (=first direction) of the engaging element 5c.

[0136] Therefore, when the engaging element 5c is incorporated into the reverse input blocking clutch 1, it is preferable to provide a convex curved surface portion in the portion of the output-side engaging portion 21 of the output member 4 that engages with the output-side engaged portion 36a.

[0137] In this example, a convex curved surface portion 37 is provided on the engaging element 5c to reduce the contact pressure at the contact point between the input member 3 and the engaging element 5b. Therefore, compared to the case where the convex curved surface portion is provided by machining the contact point of the input member 3 with the engaging element 5c, manufacturing costs can be reduced.

[0138] The composition and effects of the other parts of the fourth example are the same as those of the first example.

[0139] [Example 5] A fifth example of the embodiment of this disclosure will be described with reference to Figure 9.

[0140] In this example, the engaging element 5d has a convex portion 40b that protrudes radially (in the first direction) outward from the adjacent portions on both sides in the width direction, and is partially cylindrical, located in the middle of the radially inner surface 39b of the engaging element 5d in the width direction (= second direction). The convex portion 40b has a single arc-shaped contour when viewed from the axial direction. The convex curved portion 37a of the input-side engaging element 35 that engages with the input-side engaging element 13 is provided at two locations in the width direction of the convex portion 40b.

[0141] Furthermore, the output-side engaged portion 36b is composed of a partial cylindrical surface. The output-side engaged portion 36b has a single arc-shaped contour when viewed from the axial direction. The convex curved surface portion 38a that engages with the output-side engaged portion 21 is provided at two locations in the width direction of the output-side engaged portion 36b.

[0142] The composition and effects of the other parts of Example 5 are the same as those of Example 1.

[0143] The first to fifth embodiments of this disclosure can be combined as appropriate, as long as they do not create any inconsistencies. [Explanation of symbols]

[0144] 1. Reverse input blocking clutch 2 Pressed member 3 Input Members 4 Output component 5, 5a, 5b, 5c, 5d engager 6. Surface to be pressed 7 Housing elements 8. Large diameter cylindrical surface 9 Small diameter cylindrical surface part 10 Connection surface 11 Inward flange section 12 screw holes 13 Input side engagement portion 14 Input shaft section 15 Radial inner surface 16 Flat surface section 17 Partial cylindrical surface section 18 Radial outer surface 19 Ridge 20 Input flange section 21 Output side engagement part 22 Flat surface part 23 Partial cylindrical surface part 24 Ridge 25 Output shaft section 26 Output flange section 27 Small diameter shaft section 28 Radial rolling bearings 29 Outer ring 30a, 30b Retaining rings 31 Inner circle 32 Rolling elements 33 Plain bearings 34 Pressing surface 35 Input side engaged portion 36, 36a, 36b Output side engaged part 37, 37a, 37b Convex curved part 38, 38a, 38b Convex curved part 39 Radial inner surface 40 Convex portion 41 Radial outer surface 42 Circumferential side view 43. Biasing member 44 Retaining member 45 First Spacer Section 46 Second Spacer Section 47 Retention hole 48 Connection part 49 Retaining ring 50 Connection surface 51 Connection surface

Claims

1. A member to be pressed having a surface to be pressed on its inner circumferential surface, An input member having an input-side engaging portion arranged radially inward from the surface to be pressed, and arranged coaxially with the surface to be pressed, An output member having an output-side engaging portion located radially inward from the input-side engaging portion and arranged coaxially with the pressed surface, An engaging element having a pressing surface facing the pressed surface, an input-side engaged portion that can engage with the input-side engaging portion, and an output-side engaged portion that can engage with the output-side engaging portion, and arranged to be movable in a first direction which is the near-far direction relative to the pressed surface, Equipped with, When rotational torque is input to the input member, the engaging element moves away from the pressed surface in the first direction based on the input-side engaging portion engaging with the input-side engaged portion, and transmits the rotational torque input to the input member to the output member by engaging the output-side engaged portion with the output-side engaging portion. Conversely, when rotational torque is input in reverse to the output member, the engaging element presses the pressing surface against the pressed surface based on the output-side engaging portion engaging with the output-side engaged portion, thereby frictionally engaging the pressing surface with the pressed surface. The engaging element has a convex curved surface portion on at least one of the parts of the input-side engaged portion that engages with the input-side engaging portion and the output-side engaged portion that engages with the output-side engaging portion. Reverse input blocking clutch.

2. The convex curved portion is provided on the part of the input-side engaged portion that engages with the input-side engaged portion, such that it is convex toward the input-side engaged portion, and the input-side engaged portion has a flat surface portion on the part that engages with the input-side engaged portion. The reverse input interruption clutch according to claim 1.

3. The reverse input blocking clutch according to claim 2, wherein the outer circumferential surface of the input-side engaging portion is composed of a partially cylindrical surface portion centered on the central axis of the input member and the flat surface portion.

4. The reverse input shutoff clutch according to claim 1, wherein the convex curved surface portion is provided on the portion of the output-side engaged portion that engages with the output-side engaged portion, such that it is convex toward the output-side engaged portion, and the output-side engaged portion has a flat surface portion on the portion that engages with the output-side engaged portion.

5. The reverse input blocking clutch according to claim 4, wherein the outer circumferential surface of the output-side engaging portion is composed of a partially cylindrical surface portion centered on the central axis of the output member and the flat surface portion.

6. The reverse input shutoff clutch according to claim 1, wherein the convex curved surface portion is provided at two positions on the radially inner surface of the input-side engaged portion, which faces radially outward in the first direction of the engager, and is separated in a second direction that is perpendicular to both the first direction and the axial direction of the pressed surface.

7. The reverse input shutoff clutch according to claim 6, wherein the input-side engaged portion has a single partially cylindrical convex surface on its radially inner surface, and the convex curved surface is provided at two positions on the convex surface that are spaced apart in the second direction.

8. The reverse input shutoff clutch according to claim 6, wherein the input-side engaged portion has a connecting surface portion that connects the two convex curved surfaces and is composed of a flat surface perpendicular to the first direction.

9. The reverse input shutoff clutch according to claim 1, wherein the convex curved portion is provided at two positions within the output-side engaged portion that are separated in a second direction perpendicular to both the first direction and the axial direction of the pressed surface.

10. The reverse input shutoff clutch according to claim 6, wherein the convex curved portion is provided at two positions on the output side engaged portion that are spaced apart in the second direction.

11. The reverse input shutoff clutch according to claim 9 or 10, wherein the output-side engaged portion is composed of a single partial cylindrical surface, and the convex curved surface portion is provided at two positions on the output-side engaged portion that are spaced apart in the second direction.

12. The reverse input shutoff clutch according to claim 9 or 10, wherein the output-side engaged portion has a connecting surface portion that connects the two convex curved surfaces and is composed of a flat surface perpendicular to the first direction.

13. The reverse input blocking clutch according to claim 1, wherein the engaging element is a press-formed product of a metal plate.

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