Reverse input shutting-off clutch

Abstract

To provide a reverse input shutting-off clutch that facilitates manufacturing or assembling, can stably perform lock operation when reverse input torque is added, and can be simply connected with a motor.SOLUTION: When input torque is added, a cam receiver 2 integrated with an input shaft 1 presses a spacer 5 slidably fitted in an eccentric hole 2a. The spacer 5 is supported by an Oldham joint (swiveling supporting mechanism) 7 to revolve, thereby integrally rotating an eccentric cam 4 and an output shaft 3. With respect to reverse input torque, the spacer 5 is regulated in revolving and swiveling motion, and two rolling bearings 16 and 17 of a braking mechanism 8 receive a preload to generate constant braking force to rotations of the input shaft 1, thereby stably locking the output shaft 3. A joint member 10 that is a connection part with a motor M is integrally formed with a positioning member 15 positioning the rolling bearings 16 and 17, thereby enabling simple connection to the motor M.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 member to an output member when an input torque is applied, and locks the output member against a reverse input torque to prevent the input 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 lock 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 the inner circumference is disposed on the radial outside of the output member, and a plurality of cam surfaces are provided on the outer circumference of the output member, forming wedge-shaped spaces that gradually narrow on both sides in the circumferential direction between the inner circumference cylindrical surface of the fixed outer ring and each cam surface of the output member, and incorporating a pair of rollers and a spring that presses the rollers into the narrow part of the wedge-shaped space in each of these wedge-shaped spaces, and connecting a retainer having a column portion inserted on both sides in the circumferential direction of each wedge-shaped space to rotate integrally with the input member. Here, the radial direction is a direction perpendicular to the common axis of the input member and the output member, and the circumferential direction is a direction along a circumference that goes around the axis. The direction along the axis is also called the axial direction. The definitions of these directions are the same in the following description.

[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 it is time-consuming to fit 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 5 and 6 (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] 5 and 6, 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 be in 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 design is such that the braking force due to the sliding resistance of the cam receiver 52 against the housing 57 is greater than the frictional force, 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] In addition, input torque can be applied to the input shaft 51 from an input gear fixedly fitted to its outer periphery, and when a device incorporating this reverse input cut-off clutch is driven by a motor, there is the drawback that the connection structure with the motor becomes complicated.

[0014] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a reverse input cutoff clutch that is easy to manufacture and assemble, can stably perform a locking operation when a reverse input torque is applied, and can be easily connected to a motor. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention provides 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 that rotatably supports the input shaft and the output shaft, a rotation support mechanism that is provided between the spacer and the fixed member and supports the spacer non-rotatable but revolvable, and a braking mechanism that applies a brake to the rotation of an input side member consisting of the input shaft and the cam receiver, When an input torque is applied to a force shaft, a couple of forces acts from the input shaft to the cam receiver, causing the spacer to revolve orbitally, so that the eccentric cam and the output shaft rotate together, and when a reverse input torque is applied to the output shaft, a translational force acts from the output shaft to the cam receiver and the spacer via the eccentric cam, restricting the revolving motion of the spacer and locking the output shaft. In this reverse input cut-off clutch, the braking mechanism includes a rolling bearing incorporated between the input side member and the fixed member, and a positioning member connected to the fixed member to position the rolling bearing, and the positioning member is integrally formed with a joint member that serves as a connecting part between the fixed member and a motor that applies input torque to the input shaft (configuration 1).

[0016] According to the above-mentioned 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. In addition, 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. In addition, the connection with the motor that applies the input torque to the input shaft can be easily performed by using a joint member integrally formed with the positioning member of the braking mechanism.

[0017] The braking mechanism may be one including a preload member connected to the input shaft for applying a preload to the rolling bearings, two of the rolling bearings being arranged to sandwich the cylindrical portion of the positioning member in the radial direction, the positioning member positioning the radially outer rolling bearing between itself and the input member, and positioning the radially inner rolling bearing between itself and the preload member, the preload member applying a preload to the radially inner rolling bearing, and applying 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 a fixed member.

[0018] 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.

[0019] In the above configuration 3, it is preferable that the joint member has a window formed therein that penetrates radially toward the unlocking mechanism (configuration 4). In this way, the unlocking mechanism can be easily operated from the radial outside of the joint member. Effect of the Invention

[0020] As described above, the reverse input cutoff clutch of the present invention is easier to manufacture and assemble than the conventional locking type, and can stably perform the locking operation when a reverse input torque is applied. Also, it can be easily connected to the motor that applies the input torque to the input shaft. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a cross-sectional plan view of a reverse input cutoff clutch according to an embodiment of the present invention in a used state; [Diagram 2] FIG. 2 is an exploded perspective view of the reverse input cutoff clutch 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] A cross-sectional plan view of a reverse input cutoff clutch on which the present invention is based. [Figure 6] Exploded perspective view of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment of the present invention will be described with reference to Fig. 1 to Fig. 4. Fig. 1 shows a reverse input cutoff clutch of the embodiment in use connected to a motor M. 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 into the inner periphery of the input shaft 1, a cylindrical eccentric cam 4 integrally formed with the center portion in the axial direction of the output shaft 3, a cylindrical spacer 5 slidably fitted between the inner periphery of the cam receiver 2 and the outer periphery 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.

[0023] 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.

[0024] The housing 6 has a lid portion 6b at one end of a cylindrical portion 6a through which the output shaft 3 passes, a joint member 10 serving as a connecting part with the motor M is fitted to the other end of the cylindrical portion 6a, and the cam receiver 2, the eccentric cam 4, and the spacer 5 are housed inside. The housing 6 is connected to the motor M by a bolt 11 that passes through the lid portion 6b, the cylindrical portion 6a, the joint member 10, and the outer periphery of the motor M, and a nut 12 that is screwed onto the bolt 11. The lid portion 6b has a plurality of protrusions 6c provided at equal intervals in the circumferential direction on its outer periphery, and the protrusions 6c have through holes formed therein for fixing the housing 6 to an external member E with a bolt 13.

[0025] The joint member 10 has a shape in which an annular portion 10a that fits into the other end of the cylindrical portion 6a of the housing 6 and a disk portion 10b that fits into the outer periphery of one end of the motor M and abuts against one end face of the motor M are connected by a number of column portions 10c extending in the axial direction, and a bolt 11 for connecting the motor M is passed through each column portion 10c. A window 10d that penetrates radially toward the lock release mechanism 9 is formed between adjacent column portions 10c in the circumferential direction.

[0026] The housing 6 rotatably supports the output shaft 3 via a rolling bearing 14 assembled between the cover portion 6b and one end side small diameter portion of the output shaft 3, and rotatably supports the input shaft 1 via two rolling bearings 16, 17 assembled between the input shaft 1 and a positioning member 15 integrally formed with the joint member 10. In this example, deep groove ball bearings are used for the rolling bearings 14, 16, 17. A gap is provided between the inner peripheral surface of the cylindrical portion 6a of the housing 6 and the outer peripheral surface of the cam receiver 2, so that the input side member does not slide against the housing 6.

[0027] The input shaft 1 is provided with a key groove 1a on the inner circumference of the other end, and is connected to the motor shaft of the motor M by a key that fits into the key groove 1a so as to be rotatable together with the motor shaft. A plurality of screw holes 1b that constitute an unlocking mechanism 9 are provided circumferentially on the axially inner side of the key groove 1a, penetrating radially from the outer circumferential surface toward the other end of the output shaft 3. A male thread portion 1c formed on the outer periphery axially inner than the screw holes 1b and a cylindrical positioning portion 1d that extends axially outward from the outer periphery of a flange portion at one end constitute a part of a braking mechanism 8, as described later.

[0028] The braking mechanism 8 includes the above-mentioned positioning member 15, two rolling bearings (hereinafter also simply referred to as "bearings") 16, 17, and a preload member 18 having an L-shaped cross section that is screwed to the male threaded portion 1c of the input shaft 1. The positioning member 15 has a cover portion that is continuous with one end of the joint member 10, and a cylindrical portion that extends axially inward from the inner periphery of the cover portion, and the two bearings 16, 17, one outer and one inner, are arranged to sandwich the cylindrical portion in the radial direction.

[0029] The radially outer bearing 16 is positioned with its outer ring abutting against a stepped surface on the inner circumference of the positioning portion 1d of the input shaft 1 and its inner ring abutting against a stepped surface on the outer circumference of the cylindrical portion of the positioning member 15. Meanwhile, the radially inner bearing 17 is positioned with its outer ring abutting against an inward flange portion 15a protruding from one end of the cylindrical portion of the positioning member 15 and its inner ring abutting against a preload member 18. By screwing in the preload member 18, a preload is applied to the radially inner bearing 17 and also to the radially outer bearing 16 via the radially inner bearing 17 and the positioning member 15, thereby increasing the rotational torque of each bearing 16, 17 and applying a brake to the rotation of the input side member.

[0030] The braking mechanism can also be configured with two rolling bearings aligned axially, but it is preferable to use a configuration in which two rolling bearings are aligned radially, as in this embodiment, because this allows the entire clutch to be made more compact in the axial direction.

[0031] In addition, a disk-shaped connecting member 19 that constitutes part of the Oldham joint 7, as described below, is disposed at a position axially sandwiched between the cover portion 6b of the housing 6 and an inward flange-like connecting portion 5a provided at one end of the spacer 5.

[0032] The Oldham joint 7 is configured such that a first concave-convex fitting portion is provided on the opposing axial surfaces of the connecting member 19 and the connecting portion 5a of the spacer 5, the first fitting portion extending in the radial direction of the spacer 5 and fitting slidably into each other, and a second fitting portion is provided on the opposing axial surfaces of the connecting member 19 and the cover portion 6b of the housing 6, the second fitting portion extending in a direction perpendicular to the first fitting portion and fitting slidably into each other.

[0033] 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 19a formed on the inner surface (axially opposing surface) of the connecting member 19 and adapted to slidably fit into the recess 5b of the spacer 5.

[0034] In addition, the second concave-convex fitting portion consists of a convex portion 19b formed on the outer surface of the connecting member 19 (the axially opposing surface with the lid portion 6b of the housing 6) so as to extend in a direction perpendicular to the convex portion 19a on the inner surface of the connecting member 19, and a concave portion 6d formed on the inner surface of the lid portion 6b of the housing 6 (the axially opposing surface with the connecting member 19) into which the convex portion 19b of the connecting member 19 fits slidably.

[0035] 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 19 are respectively provided with center holes 5c and 19c through which the output shaft 3 passes, and the holes 5c and 19c 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 19 moves parallel to the axis.

[0036] The lock release mechanism 9 tightens the screw 20 screwed into the screw hole 1b at the other end of the input shaft 1 and presses it against the output shaft 3 (see Fig. 4), thereby connecting the input side member and the output side member so that they can rotate together, and prevents the output shaft 3 from being locked when a reverse input torque is applied to the output shaft 3, as described below. However, as shown in Fig. 1, normally, the screw 20 is not in contact with the output shaft 3 (the lock release mechanism 9 is not in operation), and the input side member and the output side member are not connected.

[0037] 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.

[0038] 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 guided by the connecting member 19 constituting the Oldham joint 7, and at the same time, the connecting member 19 moves leftward guided by the lid portion 6b of the housing 6, 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.

[0039] 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 19 of the Oldham joint 7 cannot slide, and the orbital movement of the spacer 5 is restricted.

[0040] 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 16, 17 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.

[0041] 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.

[0042] Here, the input side member rotates smoothly supported by the rolling bearings 16, 17 without sliding against the housing 6 in response to the input torque, and the preload applied to the rolling bearings 16, 17 does not change during use, so the braking force against the rotation of the input side member is kept constant.

[0043] Therefore, this reverse input cut-off clutch is free from the risk of locking failure due to wear of the input side members and housing 6, which is a problem with the structures of Figures 5 and 6 described above, and can perform stable locking operation for a long period of time, and can also be used under conditions in which the input shaft 1 rotates at high speed due to the drive of the motor M.

[0044] In addition, in the event of an emergency or the like, when it becomes necessary to move the input side from the output side, as shown in Fig. 4, a screwdriver (not shown) is inserted from the window 10d of the joint member 10 toward the input shaft 1 to tighten the screw 20 of the lock release mechanism 9, and the tip of the screw 20 is pressed 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, thereby applying a reverse input torque to the output shaft 3 and rotating the output side member together with the input side member. The screw 20 may have a hexagonal hole and be operated with a hexagonal wrench.

[0045] 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.

[0046] Furthermore, this reverse input cutoff clutch has the advantage that connection to the motor M can be easily performed by using the joint member 10 formed integrally with the positioning member 15 of the braking mechanism 8.

[0047] 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.

[0048] 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.

[0049] 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]

[0050] 1 Input shaft 2 Cam holder 2a eccentric hole 3 Output shaft 4 Eccentric Cam 5 Spacer 6 Housing (fixing member) 7 Oldham joint (swivel support mechanism) 8 Braking mechanism 9 Unlocking mechanism 10 Joint material 10d Window 14, 16, 17 Rolling bearings 15 Positioning member 18 Preload member 19 Connecting members 20 Screws Medium motor

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, the braking mechanism includes a rolling bearing incorporated between the input member and the fixed member, and a positioning member connected to the fixed member for positioning the rolling bearing, A reverse input cutoff clutch, characterized in that a joint member which serves as a connecting component between the fixed member and a motor which applies input torque to the input shaft is integrally formed with the positioning member.

2. 2. The reverse input cut-off clutch according to claim 1, wherein the braking mechanism includes a preload member connected to the input shaft and applying a preload to the rolling bearings, two of the rolling bearings are arranged to radially sandwich a cylindrical portion of the positioning member, the positioning member positions the radially outer rolling bearing between itself and the input side member, and positions the radially inner rolling bearing between itself and the preload member, 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.

4. 4. The reverse input cutoff clutch according to claim 3, wherein the joint member is formed with a window that penetrates radially toward the lock release mechanism.

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