Reverse input blocking clutch

Abstract

To provide a reverse input blocking clutch easy to manufacture and assemble, and capable of stably performing locking operation when reverse input torque is applied.SOLUTION: When input torque is applied, a cam receiver 2 receiving a couple of forces from an input shaft 1 presses a spacer 5 slidably fitted into an eccentric hole 2a and the spacer 5 is revolved and turned while being supported by an Oldham joint (a turn support mechanism) 7 to cause an eccentric cam 4 slidably fitted into the inner periphery of the spacer 5 to be rotated integrally with an output shaft 3. When reverse input torque is applied, the spacer 5 pushed by the eccentric cam 4 receives translational force and its revolution turning motion is restricted, and two rolling bearings 13 of a braking mechanism 8 built in between a housing 6 and the input shaft 1 receive preload to generate fixed braking force against the rotation of the input shaft 1, so that the output shaft 3 is stably locked to prevent the corotation of the output shaft 3 and the input shaft 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a locking type reverse input cut-off clutch which transmits the rotation of an input side member to an output side member when an input torque is applied, and locks the output side member against a reverse input torque to prevent the input side member from rotating. [Background technology]

[0002] In industrial machinery, when a part or the like is positioned by a motor-driven positioning device, even after the part or the like is moved to a stop position and the rotation of the motor is stopped, current is passed through the motor so that the positioning device will hold the part or the like in the stop position even if it is subjected to an external force, which consumes power. If a locking reverse input cutoff clutch is incorporated into such a positioning device, the positioning device can hold the part or the like in the stop position by locking against the force applied by the part or the like after positioning is completed, so that power can be saved by cutting off current to the motor as soon as positioning is completed. Another advantage is that even if the positioning device suddenly stops due to a power outage or the like, the positioning device is held in the stop position by the action of the reverse input cutoff clutch, ensuring safety.

[0003] An example of such a locking type reverse input cutoff clutch is described in Patent Document 1. This reverse input cutoff clutch is provided with a torque transmission means between an input member and an output member that rotate around the same axis, which transmits the rotation of the input member to the output member with a slight angular delay, a fixed outer ring having a cylindrical surface on its inner periphery is disposed radially outside the output member, and a plurality of cam surfaces are provided on the outer periphery of the output member, so that wedge-shaped spaces that gradually narrow on both circumferential sides are formed between the inner periphery cylindrical surface of the fixed outer ring and each cam surface of the output member, a pair of rollers and a spring that presses the rollers into the narrowed portion of the wedge-shaped space are incorporated in each of these wedge-shaped spaces, and a cage having pillar portions inserted on both circumferential sides of each wedge-shaped space is connected to rotate integrally with the input member.

[0004] However, the reverse input cut-off clutch of Patent Document 1 mentioned above has the drawback that complex processing (forming a cam surface) is required when manufacturing the output side member, and that it is time-consuming to incorporate small parts such as rollers and springs into the multiple wedge-shaped spaces during assembly.

[0005] In response to this, the inventors of the present invention have devised a reverse input cutoff clutch having a structure as shown in Figures 7 and 8 (Patent Application No. 2015-107078). In this reverse input cutoff clutch, an input shaft 51 and an output shaft 53 through which a fixed shaft 55 passes are arranged coaxially, a cylindrical eccentric cam 54 having an eccentric axis parallel to the axis of the output shaft 53 is provided on the input shaft 51, a cylindrical cam receiver 52 which slides against the inner peripheral surface of a housing (fixed member) 57 is provided on the input shaft 51, a circular eccentric hole 52a having the same eccentric axis as the eccentric axis of the eccentric cam 54 is formed in the cam receiver 52, the eccentric cam 54 is inserted into the eccentric hole 52a, a cylindrical spacer 56 is slidably fitted between the inner peripheral surface of the eccentric hole 52a and the outer peripheral surface of the eccentric cam 54, and an Oldham joint (swivel support mechanism) 58 which supports the spacer 56 non-rotatable but revolvable is provided between the spacer 56 and the housing 57.

[0006] The housing 57 has a lid 59 fitted onto the inner periphery at one end and a lid portion 57a ​​at the other end. The Oldham joint 58 has a connecting member 60 disposed between the spacer 56 and the lid portion 57a ​​of the housing 57, so that the connecting member 60 slides between the spacer 56 and the lid portion 57a ​​of the housing 57.

[0007] When input torque is applied to the input shaft 51, the cam receiver 52 receiving a couple of forces from the input shaft 51 presses the spacer 56, and the spacer 56 slides up and down guided by a connecting member 60 constituting an Oldham joint 58, while at the same time the connecting member 60 slides left and right guided by a housing 57, causing the spacer 56 to revolve without rotating on its axis, and the eccentric cam 54 fitted on the inner periphery of the spacer 56 and the output shaft 53 to rotate together. At this time, the cam receiver 52 rotates in a braked state due to the sliding resistance against the housing 57.

[0008] On the other hand, when a reverse input torque is applied to the output shaft 53, the eccentric cam 54 integral with the output shaft 53 presses the cam receiver 52 via the spacer 56. However, this pressing force is not a couple force, but a translational force acts on the cam receiver 52 and the spacer 56. As a result, the connecting member 60 of the Oldham joint 58 cannot slide, and the revolutionary motion of the spacer 56 is restricted, causing the output shaft 53 to be locked.

[0009] Compared to conventional locking clutches that incorporate multiple small rollers and springs, this reverse input cut-off clutch eliminates the need for complex processing when manufacturing the parts and reduces the number of parts, making it easier to manufacture and assemble. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2-271116 Summary of the Invention [Problem to be solved by the invention]

[0011] 7 and 8, when a reverse input torque is applied to the output shaft 53, the force transmitted from the output shaft 53 to the cam receiver 52 via the eccentric cam 54 and the spacer 56 does not rotate the cam receiver 52 and the input shaft 51, as described above. Also, the input side member consisting of the input shaft 51 and the cam receiver 52 and the output side member consisting of the output shaft 53 and the eccentric cam 54 are assembled so as to come into contact with each other, and although the frictional force between the input side member and the output side member tends to rotate the input side member, the frictional force is designed to be greater than the braking force due to the sliding resistance of the cam receiver 52 against the housing 57, thereby preventing the output side member and the input side member from rotating together.

[0012] However, when used under conditions in which input shaft 51 rotates at high speed due to motor drive or the like, the outer peripheral surface of cam receiver 52 and the inner peripheral surface of housing 57 will wear during use, increasing the gap between them and reducing the sliding resistance (braking force) of cam receiver 52, causing the frictional force between the input side member and the output side member to rotate the input side member (to rotate together with the output side member), which may result in a locking failure of output shaft 53.

[0013] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a reverse input cutoff clutch that is easy to manufacture and assemble and can stably perform a locking operation when a reverse input torque is applied. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention provides a rotor having an input shaft and an output shaft arranged to rotate about the same axis, a cylindrical eccentric cam having an eccentric axis parallel to the axis of the output shaft and provided on the output shaft to rotate integrally with the output shaft, a cam receiver provided on the input shaft to receive the eccentric cam in a circular eccentric hole having the same eccentric axis as the eccentric axis of the eccentric cam and to rotate integrally with the input shaft, a cylindrical spacer slidably fitted between the inner peripheral surface of the eccentric hole of the cam receiver and the outer peripheral surface of the eccentric cam, a fixed member supporting the input shaft and the output shaft rotatably, a swivel support mechanism arranged between the spacer and the fixed member to support the spacer non-rotatable but revolvable, and and a braking mechanism which brakes the rotation of an input side member consisting of an input shaft and the cam receiver, and when an input torque is applied to the input shaft, a couple of forces acts from the input shaft to the cam receiver, causing the spacer to revolve orbitally, thereby causing the eccentric cam and the output shaft to rotate together, and when a reverse input torque is applied to the output shaft, a translational force acts from the output shaft via the eccentric cam on the cam receiver and the spacer, restricting the revolving motion of the spacer, thereby locking the output shaft. In this reverse input cut-off clutch, the braking mechanism employs a configuration (configuration 1) in which a rolling bearing incorporated between the input side member and the fixed member is in a preloaded state.

[0015] According to the above configuration 1, the number of parts can be reduced and manufacturing and assembly can be facilitated compared to conventional locking types incorporating multiple small rollers and springs. Also, even when used under conditions where the input shaft is driven by a motor, the preload applied to the rolling bearing of the braking mechanism does not change during use and the braking force against the rotation of the input side member is kept constant, so that when a reverse input torque is applied to the output shaft, the output shaft can be stably locked by the action of restricting the revolutionary motion of the spacer and the braking force of the braking mechanism.

[0016] The braking mechanism may be one in which two of the rolling bearings are arranged radially on either side of a positioning member connected to the fixed member, the positioning member positions the radially outer rolling bearing between the input member and the positioning member for positioning the radially inner rolling bearing between a preload member connected to the input shaft, and the preload member applies a preload to the radially inner rolling bearing and also applies a preload to the radially outer rolling bearing via the radially inner rolling bearing and the positioning member (Configuration 2).By using the braking mechanism of Configuration 2, the entire clutch can be made more compact in the axial direction than when using a braking mechanism in which two rolling bearings to which a preload is applied are arranged axially between the input member and the fixed member.

[0017] In either of the above configurations 1 and 2, it is preferable to provide a configuration in which the input side member and the output side member consisting of the output shaft and the eccentric cam are connected so as to be rotatable together, and an unlocking mechanism is provided to prevent the output shaft from being locked when a reverse input torque is applied to the output shaft (configuration 3). In this way, even when an apparatus incorporating this reverse input blocking clutch is stopped in an emergency, the input side member and the output side member are connected by the unlocking mechanism, and the output side member and the input side member are rotated together by applying a reverse input torque, so that the position of the apparatus can be easily changed, improving the operability of the apparatus in a stopped state. Effect of the Invention

[0018] As described above, the reverse input cutoff clutch of the present invention is easier to manufacture and assemble than the conventional locking type clutch, and can stably perform the locking operation when a reverse input torque is applied. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional plan view of a reverse input cutoff clutch according to a first embodiment; [Diagram 2] An exploded perspective view of FIG. [Diagram 3] a is a cross-sectional view taken along line III-III in FIG. 1, and b is a cross-sectional view corresponding to a that explains the clutch operation. [Figure 4] FIG. 2 is a cross-sectional plan view of a main part for explaining the operation of the lock release mechanism corresponding to FIG. 1; [Diagram 5] FIG. 11 is a cross-sectional plan view of a reverse input cutoff clutch according to a second embodiment; [Figure 6] Exploded perspective view of FIG. [Figure 7] A cross-sectional plan view of a reverse input cutoff clutch on which the present invention is based. [Figure 8] Exploded perspective view of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 6. Fig. 1 to Fig. 4 show the first embodiment. This reverse input cutoff clutch is basically composed of a cylindrical input shaft 1, a cylindrical cam receiver 2 integrally formed with a flange portion on one end side of the input shaft 1, an output shaft 3 having the other end slidably fitted on the inner circumference of the input shaft 1, a cylindrical eccentric cam 4 integrally formed with the center of the axial direction of the output shaft 3, a cylindrical spacer 5 slidably fitted between the inner circumference of the cam receiver 2 and the outer circumference of the eccentric cam 4, a housing (fixed member) 6 that rotatably supports the input shaft 1 and the output shaft 3, an Oldham joint (swivel support mechanism) 7 that is disposed between the spacer 5 and the housing 6 and supports the spacer 5 non-rotatably but revolvably, a braking mechanism 8 that brakes the rotation of an input side member consisting of the input shaft 1 and the cam receiver 2, and a lock release mechanism 9 that connects the input side member to an output side member consisting of the output shaft 3 and the eccentric cam 4.

[0021] The input shaft 1 and the output shaft 3 are arranged to rotate about the same axis, and the cam receiver 2 integral with the input shaft 1 also has the same axis as the axis of the input shaft 1. On the other hand, the eccentric cam 4 integral with the output shaft 3 has an eccentric axis parallel to the axis of the output shaft 3, and the cam receiver 2 has an eccentric axis identical to that of the eccentric cam 4, and is formed with a circular eccentric hole 2a that receives the spacer 5 and the eccentric cam 4.

[0022] The housing 6 is composed of a first housing member 10 having a cover portion 10a formed at one end of a cylindrical portion and a second housing member 11 having a male thread portion 11a formed on the outer peripheral surface of a small diameter cylindrical portion continuing to the other end of the large diameter cylindrical portion, and is integrated by fitting the cylindrical portion of the first housing member 10 into the inner periphery of the large diameter cylindrical portion of the second housing member 11, with the cam receiver 2, eccentric cam 4 and spacer 5 housed inside. Here, protrusions 10b, 11b are provided at corresponding circumferential positions on the outer periphery of the cover portion 10a of the first housing member 10 and the outer periphery of one end of the large diameter cylindrical portion of the second housing member 11, and both housing members 10, 11 can be fastened together by utilizing through holes formed in each of the protrusions 10b, 11b.

[0023] The first housing member 10 rotatably supports the output shaft 3 via a rolling bearing 12 assembled between the cover portion 10a and one end side small diameter portion of the output shaft 3. Meanwhile, the second housing member 11 rotatably supports the input shaft 1 via two rolling bearings 13 assembled between the small diameter cylindrical portion and the input shaft 1. In this example, the rolling bearings 12, 13 are deep groove ball bearings. Also, gaps are provided between the inner peripheral surface of the cylindrical portion of the first housing member 10 and the outer peripheral surface of the cam receiver 2, and between the step surface on the axial inner side of the inner circumference of the second housing member 11 and the outer surface of the flange portion of the input shaft 1, so that the input side member does not slide against the housing 6.

[0024] Two rolling bearings (hereinafter, simply referred to as "bearings") 13 supporting the input shaft 1 face each other with their inner rings sandwiched between a spacer 14 fitted in an annular groove on the outer periphery of the input shaft 1, and are assembled in such a manner that the outer ring of the axially inner bearing 13 abuts against a stepped surface on the inner periphery of the small diameter cylindrical part of the second housing member 11, and the outer ring of the axially outer bearing 13 abuts against a preload member 15 screwed into the male threaded part 11a of the second housing member 11. The preload member 15 abuts against the outer ring of the axially outer bearing 13 at an annular protrusion 15a protruding axially inward from the inner periphery of the inward flange, and a preload is applied to the two bearings 13 by screwing in the preload member 15. This increases the rotational torque of each bearing 13, thereby forming a braking mechanism 8 that brakes the rotation of the input side member.

[0025] In addition, a disk-shaped connecting member 16 that constitutes part of the Oldham joint 7, as described below, is disposed at a position axially sandwiched between the cover portion 10a of the first housing member 10 and an inward flange-like connecting portion 5a provided at one end of the spacer 5.

[0026] The Oldham joint 7 is configured such that a first concave-convex fitting portion is provided on the axially opposing surfaces of the connecting member 16 and the connecting portion 5a of the spacer 5, the first concave-convex fitting portion extending in the radial direction of the spacer 5 and fitting slidably into each other, and a second concave-convex fitting portion is provided on the axially opposing surfaces of the connecting member 16 and the cover portion 10a of the first housing member 10, the second concave-convex fitting portion extending in a direction perpendicular to the first concave-convex fitting portion and fitting slidably into each other.

[0027] Here, the first concave-convex fitting portion consists of a recess 5b formed to extend radially on the outer surface (axially opposing surface) of the connecting portion 5a of the spacer 5, and a protrusion 16a formed on the inner surface (axially opposing surface) of the connecting member 16 and adapted to slidably fit into the recess 5b of the spacer 5.

[0028] In addition, the second concave-convex fitting portion consists of a convex portion 16b formed on the outer surface of the connecting member 16 (the axially opposing surface with the lid portion 10a of the first housing member 10) so as to extend in a direction perpendicular to the convex portion 16a on the inner surface of the connecting member 16, and a concave portion 10c formed on the inner surface of the lid portion 10a of the first housing member 10 (the axially opposing surface with the connecting member 16) into which the convex portion 16b of the connecting member 16 fits slidably.

[0029] As described above, the spacer 5 is supported non-rotatably but revolvably relative to the housing 6 by this Oldham joint 7. The connecting portion 5a of the spacer 5 and the connecting member 16 are respectively provided with center holes 5c and 16c through which the output shaft 3 passes, and the holes 5c and 16c are both formed to have a size such that they do not interfere with the output shaft 3 when the spacer 5 revolves and the connecting member 16 moves parallel to the axis.

[0030] The unlocking mechanism 9 has a plurality of circumferentially threaded holes 1a penetrating radially from the outer circumferential surface of the input shaft 1 toward the other end of the output shaft 3, and connects the input side member and the output side member so that they can rotate together by tightening screws 17 screwed into each of the threaded holes 1a and pressing them against the output shaft 3 (see FIG. 4), thereby preventing the output shaft 3 from being locked when a reverse input torque is applied to the output shaft 3 as described below. However, normally, as shown in FIG. 1, the screws 17 are not in contact with the output shaft 3 (the unlocking mechanism 9 is not in operation), and the input side member and the output side member are not connected.

[0031] This reverse input cutoff clutch has the above-mentioned configuration, and compared to a conventional lock type clutch incorporating a plurality of small rollers and springs, it has a smaller number of parts and can be easily manufactured and assembled.

[0032] Next, the operation of the reverse input cutoff clutch will be described. First, in normal operation when the input side member and the output side member are not connected, when a counterclockwise input torque is applied to the input shaft 1 from the state shown in Fig. 3(a), the cam receiver 2 receives a couple of forces from the input shaft 1 and presses the spacer 5 slidably fitted in its eccentric hole 2a, as shown in Fig. 3(b), and the spacer 5 moves upward while being guided by the connecting member 16 constituting the Oldham joint 7, and at the same time, the connecting member 16 moves leftward while being guided by the cover portion 10a of the first housing member 10, so that the spacer 5 revolves counterclockwise without rotating on its axis relative to the housing 6. Then, with the revolution of the spacer 5, the eccentric cam 4 slidably fitted on the inner periphery of the spacer 5 rotates eccentrically, and the output shaft 3 integral with the eccentric cam 4 rotates.

[0033] On the other hand, when a reverse input torque is applied to the output shaft 3, the eccentric cam 4 integral with the output shaft 3 presses the cam receiver 2 via the spacer 5. However, this pressing force is not a couple force, but a translational force acts on the cam receiver 2 and the spacer 5. As a result, the connecting member 16 of the Oldham joint 7 cannot slide, and the revolutionary motion of the spacer 5 is restricted.

[0034] At this time, the input shaft 1, which is assembled so as to come into contact with the output side member (output shaft 3 and eccentric cam 4), receives a frictional force from the output side member in a direction in which it rotates together with the output side member. However, by adjusting the preload of the two rolling bearings 13 so that the braking force of the braking mechanism 8 is greater than this frictional force, it is possible to prevent the output side member and the input side member from rotating together due to this frictional force.

[0035] That is, in this reverse input cutoff clutch, the output shaft 3 can be reliably locked against reverse input torque by the action of restricting the revolutionary motion of the spacer 5 and the braking force of the braking mechanism 8.

[0036] Here, the input side member rotates smoothly supported by the rolling bearing 13 without sliding against the housing 6 in response to the input torque, and the preload applied to the rolling bearing 13 does not change during use, so the braking force against the rotation of the input side member is kept constant.

[0037] Therefore, this reverse input cutoff clutch is free from the risk of locking failure due to wear of the input side member and housing 6, which is a problem with the structures of Figures 7 and 8 described above, and can perform stable locking operation for a long period of time, and can also be used under conditions where the input shaft 1 is rotated at high speed by a motor.

[0038] In addition, in the event of an emergency or the like where it becomes necessary to move the input side from the output side, as shown in Fig. 4, by tightening the screw 17 of the lock release mechanism 9 with a screwdriver (not shown) and pressing the tip of the screw 17 against the outer circumferential surface of the other end of the output shaft 3 to connect the input side member and the output side member, it is possible to apply a reverse input torque to the output shaft 3 and rotate the output side member together with the input side member. Note that the screw 17 may be a hexagonal socket type that can be operated with a hexagonal wrench.

[0039] Therefore, for example, if a device incorporating this reverse input cut-off clutch is forced to an emergency stop due to a power outage or the like, the input side member and the output side member can be connected by the lock release mechanism 9 as described above, and a reverse input torque can be manually applied to rotate the output side member and the input side member, thereby moving the device to a position suitable for restarting, and enabling the restart work to be carried out efficiently.

[0040] 5 and 6 show a second embodiment. This embodiment is based on the first embodiment, with the configuration of the braking mechanism and related members changed. Below, the differences from the first embodiment will be described.

[0041] In this second embodiment, the input shaft 1 has a male threaded portion 1b formed on its outer periphery axially inwardly of the screw hole 1a for the lock release mechanism 9, and a cylindrical positioning portion 1c extending axially outward is provided on the outer periphery of the flange portion.

[0042] The housing 18 has a shape in which the cylindrical portion of the first housing member 10 of the first embodiment is extended to the other end side, and is adapted to be attached to an external member (not shown) by utilizing a through hole of a protruding piece 18b formed on the outer periphery of the lid portion 18a. A recess 18c into which the protruding portion 16b of the connecting member 16 slidably fits is formed on the inner surface of the lid portion 18a, and a female screw portion 18d is formed on the inner periphery of the other end of the cylindrical portion.

[0043] The braking mechanism 19 is composed of a lid-shaped positioning member 20 that is screwed into the female thread portion 18d of the housing 18, two rolling bearings, outer and inner, that are arranged to radially sandwich a cylindrical portion extending axially inward from the inner circumference of the positioning member 20, and a preload member 23 with an L-shaped cross section that is screwed into the male thread portion 1b of the input shaft 1.

[0044] The radially outer bearing 21 is positioned with its outer ring abutting on a stepped surface on the inner circumference of the positioning portion 1c of the input shaft 1 and its inner ring abutting on a stepped surface on the outer circumference of the cylindrical portion of the positioning member 20. Meanwhile, the radially inner bearing 22 is positioned with its outer ring abutting on an inward flange portion 20a protruding from one end of the cylindrical portion of the positioning member 20 and its inner ring abutting on a preload member 23. By screwing in the preload member 23, a preload is applied to the radially inner bearing 22, and a preload is applied to the radially outer bearing 21 via the radially inner bearing 22 and the positioning member 20.

[0045] The reverse input cut-off clutch of this second embodiment provides the same operational effects as the first embodiment, and in addition, as described above, the two rolling bearings 21, 22 that constitute the braking mechanism 19 are assembled side-by-side in the radial direction, which has the advantage that the entire clutch can be made more compact in the axial direction compared to the first embodiment, in which the two rolling bearings 13 of the braking mechanism 8 are assembled side-by-side in the axial direction.

[0046] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims.

[0047] For example, in addition to the unlocking mechanisms described in the above embodiments, various configurations for connecting the input side member and the output side member so as to be rotatable together may be used.

[0048] Furthermore, the swivel support mechanism is not limited to the Oldham joint of each embodiment, but may be any mechanism that has the function of supporting the spacer between the spacer and a fixed member such as a housing so as to be non-rotatable but revolvable. [Explanation of symbols]

[0049] 1 Input shaft 2 Cam holder 2a eccentric hole 3 Output shaft 4 Eccentric Cam 5 Spacer 6, 18 Housing (fixing member) 7 Oldham joint (swivel support mechanism) 8, 19 Braking mechanism 9 Unlocking mechanism 12, 13, 21, 22 Rolling bearings 14 Maza 15, 23 Preload member 16 Connecting members 17 Screw 20 Positioning member

Claims

1. the eccentric cam is provided on the input shaft so as to rotate integrally with the input shaft, the eccentric cam having an eccentric axis parallel to the axis of the output shaft, the eccentric cam being provided on the input shaft so as to receive the eccentric cam in a circular eccentric hole having the same eccentric axis as the eccentric axis of the eccentric cam and to rotate integrally with the input shaft, a cylindrical spacer slidably fitted between an inner peripheral surface of the eccentric hole of the cam receiver and an outer peripheral surface of the eccentric cam, a fixed member which rotatably supports the input shaft and the output shaft, a rotation support mechanism which is provided between the spacer and the fixed member and which supports the spacer non-rotatably but revolvably, and a braking mechanism which applies a brake to rotation of an input side member consisting of the input shaft and the cam receiver, When an input torque is applied to the input shaft, a force couple acts on the cam receiver from the input shaft, causing the spacer to revolve, and the eccentric cam and the output shaft to rotate together. When a reverse input torque is applied to the output shaft, a translational force acts on the cam receiver and the spacer from the output shaft via the eccentric cam, and the revolutionary orbital motion of the spacer is restricted, thereby locking the output shaft, 2. The reverse input cutoff clutch, wherein the braking mechanism is in a state where a preload is applied to a rolling bearing installed between the input side member and the fixed member.

2. 2. The reverse input cut-off clutch according to claim 1, wherein the braking mechanism includes two rolling bearings arranged radially on either side of a positioning member connected to the fixed member, the positioning member positions the radially outer rolling bearing between the input side member and the positioning member, and positions the radially inner rolling bearing between the input side member and a preload member connected to the input shaft, and the preload member applies a preload to the radially inner rolling bearing and also applies a preload to the radially outer rolling bearing via the radially inner rolling bearing and the positioning member.

3. 3. The reverse input cut-off clutch according to claim 1, further comprising an unlocking mechanism that connects the input side member and the output side member consisting of the output shaft and the eccentric cam so as to be rotatable together, and prevents the output shaft from locking when a reverse input torque is applied to the output shaft.

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