Reverse input cutoff clutch

Abstract

To provide a structure that enables switching between an effective state and an ineffective state of a reverse input cutoff function for preventing transmission of torque reversely input to an output member to an input member.SOLUTION: An engagement element 5 includes a release engagement part 37 disposed on a radial inner side of a release ring 6. The release ring 6 can be switched between a first state where an insertion part 15 is inserted into a discontinuous part 43 and a diameter is expanded by elastically expanding the circumferential width of the discontinuous part 43 and where the release engagement part 37 does not come into contact with an inner peripheral surface 62 of the release ring 6 while a pressing surface is pressed against a pressed surface 8 and a second state where the engagement between the discontinuous part 43 and the insertion part 15 is released and the diameter is contracted through elastic restoration and where the pressing of the pressing surface against the pressed surface 8 is inhibited on the basis of the engagement between the inner peripheral surface 62 of the release ring 6 and the release engagement part 37.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a reverse input cutoff clutch that transmits rotational torque input to an input member to an output member, while completely cutting off rotational torque that is reversely input to the output member, so that it is not transmitted to the input member, or that transmits only a portion of the torque to the input member and cuts off the remainder. [Background technology]

[0002] A reverse input cut-off clutch has 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 reduction mechanism, and has the function of transmitting the rotational torque input to the input member to the output member, while completely cutting off the rotational torque input in reverse to the output member, so that it is not transmitted to the input member, or by transmitting only a portion of it to the input member and cutting off the remainder.

[0003] Reverse input cutoff clutches include locking type reverse input cutoff clutches equipped with a mechanism that prevents the output member from rotating when a rotational torque is input to the output member, and free type reverse input cutoff clutches equipped with a mechanism that causes the output member to spin freely when a rotational torque is input to the output member.Whether to use a locking type reverse input cutoff clutch or a free type reverse input cutoff clutch is determined appropriately depending on the application of the device into which the reverse input cutoff clutch is incorporated, etc.

[0004] International Publication No. 2019 / 026794 describes a locking reverse input cutoff clutch that includes a pressed member, an input member, an output member, and an engagement element.

[0005] The pressed member has a pressed surface on its inner circumferential surface.

[0006] The input member has an input-side engaging portion disposed radially inside the pressed surface, and is disposed coaxially with the pressed surface.

[0007] The output member has an output-side engaging portion disposed radially inward of the input-side engaging portion, and is disposed coaxially with the pressed surface.

[0008] The engaging element has a pressing surface facing the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion, and is arranged so as to be able to move in a first direction, which is the direction towards or away from the pressed surface.

[0009] In the reverse input cutoff clutch, when rotational torque is input to the input member, the input-side engaging portion engages with the input-side engaged portion, causing the engaging element to move in a direction away from the pressed surface and engage the output-side engaged portion with the output-side engaging portion, thereby transmitting the rotational torque input to the input member to the output member. On the other hand, when rotational torque is reversely input to the output member, the output-side engaging portion engages with the output-side engaged portion, causing the engaging element to move in a direction approaching the pressed surface, pressing the pressing surface against the pressed surface and frictionally engaging the pressing surface against the pressed surface. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Publication No. 2019 / 026794 Brochure Summary of the Invention [Problem to be solved by the invention]

[0011] The reverse input cutoff clutch described in WO 2019 / 026794, once installed in the torque transmission path of a mechanical device, does not transmit torque reversely input to the output member to the input member, regardless of the direction of rotation. Therefore, if, for example, a failure occurs in the drive source connected to the input member and torque cannot be input from the input member to the reverse input cutoff clutch, even if an attempt is made to rotate the output member to change the position or posture of the driven member connected to the output member in order to ensure safety, the rotation of the output member will be locked.

[0012] The present disclosure aims to realize a reverse input blocking clutch structure that can switch between enabling and disabling a reverse input blocking function that prevents torque reversely input to an output member from being transmitted to an input member. [Means for solving the problem]

[0013] The reverse input disconnecting clutch of the first aspect of the present disclosure includes: a pressed member having a pressed surface on its inner circumferential surface; an input member having an input-side engaging portion disposed radially inside the pressed surface and disposed coaxially with the pressed surface; an output member having an output side engaging portion disposed radially inward of the input side engaging portion and disposed coaxially with the pressed surface; an engaging element having a pressing surface facing the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion, the engaging element being arranged to be movable in a radial direction; a release ring configured in a segmented annular shape having a discontinuous portion on its inner circumferential surface and at one location in the circumferential direction; and an expanding member having an insertion portion that is inserted into the discontinuous portion.

[0014] The engagement piece has a release engagement portion disposed radially inside the release ring.

[0015] The release ring is switchable between a first state in which the insertion portion is inserted into the discontinuous portion, elastically expanding the circumferential width of the discontinuous portion, thereby expanding the diameter thereof, and the release engagement portion does not contact the inner peripheral surface of the release ring even when the pressing surface is pressed against the pressed surface; and a second state in which the engagement between the discontinuous portion and the insertion portion is released, and the release ring is contracted in diameter by elastically restoring itself, and the pressing surface is prevented from being pressed against the pressed surface based on the engagement between the inner peripheral surface of the release ring and the release engagement portion.

[0016] When the release ring is switched to the first state, when a rotational torque is input to the input member, the engaging element moves away from the pressed surface based on the engagement of the input side engaging portion with the input side engaged portion, and engages the output side engaged portion with the output side engaging portion, thereby transmitting the rotational torque input to the input member to the output member, whereas when a rotational torque is input in the reverse direction to the output member, the output side engaging portion engages with the output side engaged portion, and presses the pressing surface against the pressed surface, causing the pressing surface to frictionally engage with the pressed surface.

[0017] When the release ring is switched to the second state, the engagement element transmits torque between the input member and the output member regardless of the direction of torque transmission between the input member and the output member.

[0018] In the reverse input disconnection clutch of the second aspect of the present disclosure, in the reverse input disconnection clutch of the first aspect of the present disclosure, the expanding member is configured to be able to move relative to the pressed member and to be able to insert and remove the insertion portion into and from the discontinuous portion based on this movement.

[0019] In the reverse input disconnection clutch of the third aspect of the present disclosure, in the reverse input disconnection clutch of the second aspect of the present disclosure, the insertion portion is inserted into the discontinuous portion from the radially inner side toward the radially outer side, and is removed from the radially outer side toward the radially inner side.

[0020] In the reverse input disconnection clutch of the fourth aspect of the present disclosure, in the reverse input disconnection clutch of the second aspect of the present disclosure, the insertion portion is inserted into the discontinuous portion from the radially outer side toward the radially inner side, and is removed from the radially inner side toward the radially outer side.

[0021] In a reverse input cutoff clutch of a fifth aspect of the present disclosure, in the reverse input cutoff clutch of the fourth aspect of the present disclosure, the expanding diameter member is configured by a screw member that is radially screwed onto the pressed member and has the insertion portion at its radially inner end.

[0022] A reverse input cutoff clutch of a sixth aspect of the present disclosure is the reverse input cutoff clutch of any one of the second to fourth aspects of the present disclosure, a feed screw shaft having a feed screw portion on an outer peripheral surface and supported by the pressed member so as to be rotatable only; The diameter expanding member has rack teeth that engage with the feed screw portion, and is supported so as to be movable relative to the pressed member in association with rotation of the feed screw shaft.

[0023] In a seventh aspect of the present disclosure, in the reverse input cutoff clutch of any of the first to sixth aspects of the present disclosure, at least a rear portion of the discontinuous portion in an insertion direction of the insertion portion relative to the discontinuous portion has a circumferential width that increases toward the rear side in the insertion direction. Note that when the insertion portion is inserted into the discontinuous portion from the radially inner side toward the radially outer side, the rear side in the insertion direction is the radially inner side, and when the insertion portion is inserted into the discontinuous portion from the radially outer side toward the radially inner side, the rear side in the insertion direction is the radially outer side.

[0024] In a reverse input cutoff clutch of an eighth aspect of the present disclosure, in the reverse input cutoff clutch of any of the first to seventh aspects of the present disclosure, at least a front portion of the insertion portion in an insertion direction of the insertion portion relative to the discontinuous portion has a circumferential width that decreases toward the front side in the insertion direction. Note that when the insertion portion is inserted into the discontinuous portion from the radially inner side toward the radially outer side, the front side in the insertion direction is the radially outer side, and when the insertion portion is inserted into the discontinuous portion from the radially outer side toward the radially inner side, the front side in the insertion direction is the radially inner side.

[0025] In a reverse input disconnection clutch of a ninth aspect of the present disclosure, in a reverse input disconnection clutch of any of the first to eighth aspects of the present disclosure, the pressed member has a circumferential groove on its inner surface that is axially offset from the pressed surface, into which the release ring enters when the release ring is switched to the first state.

[0026] In a reverse input disconnection clutch of a tenth aspect of the present disclosure, in a reverse input disconnection clutch of any of the first to ninth aspects of the present disclosure, the engaging element includes an engaging element main body having the pressing surface, the input side engaged portion, and the output side engaged portion, and the release engaging portion is configured to protrude axially from the engaging element main body.

[0027] In the reverse input disconnection clutch of the 11th aspect of the present disclosure, in the reverse input disconnection clutch of the 10th aspect of the present disclosure, the release engagement portion has a protrusion that protrudes radially outward at a portion that is located farther from the engagement element body in the axial direction than the portion that engages with the inner surface of the release ring.

[0028] In the reverse input disconnection clutch of the twelfth aspect of the present disclosure, in the reverse input disconnection clutch of any one of the first to eleventh aspects of the present disclosure, the engaging element is composed of a plurality of engaging elements arranged at different positions in the circumferential direction. [Effects of the Invention]

[0029] According to the reverse input cutoff clutch of one aspect of the present disclosure, it is possible to switch between enabling and disabling the reverse input cutoff function that does not transmit torque reversely input to the output member to the input member. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1(a) is an oblique view of a reverse input cutoff clutch of a first example of an embodiment of the present disclosure, and FIG. 1(b) is an end view of the reverse input cutoff clutch of the first example as viewed from the input member side in the axial direction. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] Figure 3(a) is a cross-sectional view similar to Figure 2, with some components omitted and showing the release ring in a state where it has been elastically expanded by a diameter expanding member, and Figure 3(b) is a cross-sectional view taken along line BB of Figure 3(a). [Figure 4] FIG. 4(a) is a cross-sectional view similar to FIG. 2, with some components omitted, showing the releasing ring in a contracted state after the elastic expansion of the releasing ring by the expanding member has been released, and FIG. 4(b) is a cross-sectional view taken along CC in FIG. 4(a). [Figure 5] 5(a) to 5(c) are enlarged views corresponding to part D in FIG. 3(b), sequentially showing the process of elastically expanding the diameter of the releasing ring by the diameter expanding member. [Figure 6] FIG. 6 is a perspective view of the release ring and the diameter expanding member. [Figure 7] 7 is a cross-sectional view taken along the line E-E of FIG. 2, with the biasing member omitted. [Figure 8] FIG. 8 is a view similar to FIG. 7, showing a state in which a rotational torque is input to the input member. [Figure 9] FIG. 9 is a view similar to FIG. 7, showing a state in which a rotational torque is reversely input to the output member. [Figure 10] Figure 10(a) is a view corresponding to the upper end of Figure 1(b) of a reverse input cut-off clutch of a second example of an embodiment of the present disclosure, Figure 10(b) is an FF cross-sectional view of Figure 10(a), and Figure 10(c) is a view from above of Figure 10(b). [Figure 11] Figure 11(a) is a view corresponding to the upper end of Figure 1(b) of a reverse input cut-off clutch of a third example of an embodiment of the present disclosure, Figure 11(b) is a cross-sectional view taken along line GG of Figure 11(a), and Figure 11(c) is a view from above of Figure 11(b). [Figure 12] 12(a) to 12(c) are views similar to FIGS. 5(a) to 5(c), sequentially showing the process of elastically expanding the diameter of the releasing ring by the diameter expanding member in the third example. [Figure 13] FIG. 13(a) is a cross-sectional view of a fourth example of an embodiment of the present disclosure, corresponding to FIG. 11(b), and FIG. 13(b) is a view seen from above FIG. 13(a). [Figure 14] FIG. 14(a) is a cross-sectional view of a fifth example of an embodiment of the present disclosure, corresponding to FIG. 11(b), and FIG. 14(b) is a view seen from above FIG. 14(a). DETAILED DESCRIPTION OF THE INVENTION

[0031] [Example 1] A first example of an embodiment of the present disclosure will be described with reference to FIGS.

[0032] In the following description, unless otherwise specified, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction of the reverse input disconnection clutch 1. The axial direction, radial direction, and circumferential direction of the reverse input disconnection clutch 1 coincide with the axial direction, radial direction, and circumferential direction of the pressed surface 8 of the pressed member 2, the input member 3, and the output member, respectively. One axial side is the input member 3 side (right side in FIG. 1), and the other axial side is the output member 4 side (left side in FIG. 1).

[0033] The direction of the pressing surface 34 of the engaging element 5 toward or away from the pressed surface 8 is defined as the first direction (the up-and-down direction in FIGS. 1(a) to 4(b) and 7 to 9), and the direction perpendicular to both the axial direction of the pressed surface 8 and the first direction is defined as the second direction (the front-to-back direction in FIGS. 2, 3(a) and 4(a), and the left-to-right direction in FIGS. 1(a), 1(b), 3(b), 4(b) and 7 to 9). With respect to the engaging element, the direction coinciding with the first direction is defined as its radial direction (the direction indicated by arrow α in FIG. 7), and the direction coinciding with the second direction is defined as its width direction (the direction indicated by arrow β in FIG. 7).

[0034] <Explanation of the structure of the reverse input cutoff clutch> The reverse input cutoff clutch 1 includes a pressed member 2, an input member 3, an output member 4, an engagement element 5, a release ring 6, and a diameter expanding member .

[0035] The reverse input cutoff clutch 1 further includes a release ring 6 and an expansion member 7, thereby enabling or disabling the reverse input cutoff function. When the reverse input cutoff function of the reverse input cutoff clutch 1 is enabled, when rotational torque is input to the input member 3, the engaging element 5 moves in a direction away from the pressed member 2 based on the engagement between the input member 3 and the engaging element 5, engaging the output member 4 and transmitting the rotational torque input to the input member 3 to the output member 4. On the other hand, when rotational torque is input in reverse to the output member 4, the engaging element 5 moves in a direction away from the pressed surface based on the engagement between the output member 4 and the engaging element 5, pressing the pressing surface 34 of the engaging element 5 against the pressed surface 8 of the pressed member 2 and establishing frictional engagement. As a result, the reverse input cutoff clutch 1 transmits the rotational torque input to the input member 3 to the output member 4, but completely cuts off the rotational torque input in reverse to the output member 4, either by not transmitting it to the input member 3 or by transmitting only a portion of it to the input member 3 and cutting off the remainder.

[0036] When the reverse input blocking function of the reverse input blocking clutch 1 is disabled, the engaging element 5 transmits torque between the input member 3 and the output member 4 regardless of the direction of torque transmission between the input member 3 and the output member 4.

[0037] The materials for the pressed member 2, input member 3, output member 4, and engaging element 5 are not particularly limited as long as they can ensure the necessary mechanical properties such as strength. For example, these materials can be metals such as iron alloys, copper alloys, and aluminum alloys, as well as synthetic resins mixed with reinforcing fibers as needed. Furthermore, the pressed member 2, input member 3, output member 4, and engaging element 5 can be made of the same material or different materials.

[0038] When the reverse input blocking function of the reverse input blocking clutch 1 is active, lubricant can be applied to the contacting portions of the pressed member 2, input member 3, output member 4, and engaging member 5, as long as the lubricant does not impede the function. Alternatively, at least one of the pressed member 2, input member 3, output member 4, and engaging member 5 can be made of oil-impregnated metal.

[0039] The pressed member 2 has a pressed surface 8 on its inner circumferential surface. The pressed surface 8 faces the pressing surface 34 of the engaging element 5, and has the function of preventing or restricting rotation of the engaging element 5 by frictionally engaging with the pressing surface 34 of the engaging element 5 when the engaging element 5 moves in a direction approaching the pressed surface 8 in the first direction. Furthermore, the input-side engaging portion 18 of the input member 3, the output-side engaging portion 22 of the output member 4, and the engaging element 5 are rotatably arranged radially inside the pressed surface 8.

[0040] The pressed member 2 is supported and fixed to a fixed part such as a housing that does not rotate even when in use, and its rotation is restricted, or it is constituted by the fixed part. In other words, the pressed member 2 does not rotate even when in use. In this example, the pressed member 2 is supported and fixed to the fixed part, and its rotation is restricted.

[0041] The pressed surface 8 has an annular shape when viewed from the axial direction. The shape of the pressed surface 8 may be a cylindrical surface shape whose inner diameter does not change in the axial direction, or a non-cylindrical surface shape whose inner diameter changes in the axial direction, but in this example, it is a cylindrical surface shape.

[0042] The structure of the pressed member 2 is not limited as long as it has a pressed surface 8 on its inner circumferential surface. The structure for disposing, supporting, and operating the release ring 6 and the diameter-expanding member 7 can be provided in the fixed portion separately from the pressed member 2, or can be provided in the pressed member 2. For example, as shown in FIGS. 2, 3(a), and 3(b), the pressed member 2 or the fixed portion can be provided with a structure that accommodates the release ring 6 so that the release ring 6 does not impede the reverse input blocking function of the reverse input blocking clutch 1 when the release ring 6 is in the first state in which it elastically expands in diameter. For example, the pressed member 2 can have a circumferential groove 12 or a large-diameter portion on its inner circumferential surface axially offset from the pressed surface 8, into which the release ring 6 enters when the release ring 6 is switched to the first state.

[0043] Furthermore, the structure for positioning, supporting, and functioning the input member 3 and / or the output member 4 can be provided in the fixed portion separately from the pressed member 2, or can be provided in the pressed member 2.

[0044] In this example, the pressed member 2 has an inner peripheral surface in the shape of a stepped cylindrical surface. That is, the inner peripheral surface of the pressed member 2 is formed by connecting a large-diameter cylindrical surface portion 9 on one axial side with a small-diameter cylindrical surface portion 10 on the other axial side by a connecting surface portion 11 facing one axial side. In this example, the pressed surface 8 is formed by the other axial side portion of the large-diameter cylindrical surface portion 9.

[0045] In this example, the circumferential groove 12, into which the release ring 6 enters when the release ring 6 elastically expands in diameter, is provided around the entire circumference of the large-diameter cylindrical surface portion 9 in the axial middle portion, which is adjacent to one axial side of the pressed surface 8.

[0046] In this example, the pressed member 2 has a guide portion 13 for the diameter expanding member. The guide portion 13 for the diameter expanding member supports the diameter expanding member 7 so that it can move only in a predetermined direction relative to the pressed member 2. The predetermined direction coincides with the direction in which the insertion portion 15 of the diameter expanding member 7 is inserted into or removed from the discontinuous portion 43 of the release ring 6, which is the radial direction in this example.

[0047] The guide portion 13 for the diameter expansion member can be formed by a hole, a notch, a guide rail, or the like formed along the predetermined direction. In this example, the guide portion 13 for the diameter expansion member is formed by a through hole that penetrates radially at one circumferential location on one axial end of the pressed member 2, and the through hole has a rectangular opening shape. The radially inner end of the guide portion 13 for the diameter expansion member opens into a portion of the large-diameter cylindrical surface portion 9 that is located on one axial side of the circumferential groove 12.

[0048] In this example, the pressed member 2 has a notch 14 that opens to both axial sides and radially inward in a portion of the large-diameter cylindrical surface portion 9 that is sandwiched between the circumferential groove 12 and the diameter-expansion-member guide portion 13 in the axial direction. One axial end of the notch 14 opens to the diameter-expansion-member guide portion 13, and the other axial end of the notch 14 opens to the circumferential groove 12. The radial position of the bottom of the notch 14 is substantially the same as the radial position of the bottom of the circumferential groove 12. The notch 14 is a portion that prevents the portion of the large-diameter cylindrical surface portion 9 that is sandwiched between the circumferential groove 12 and the diameter-expansion-member guide portion 13 in the axial direction from interfering with the insertion portion 15 when the diameter of the releasing ring 6 is elastically expanded by inserting the insertion portion 15 of the diameter-expansion-member 7 into the discontinuous portion 43 of the releasing ring 6.

[0049] In this example, the pressed member 2 has an inward flange portion 16 that protrudes radially inward at the other axial end of the small-diameter cylindrical surface portion 10. The small-diameter cylindrical surface portion 10 and the inward flange portion 16 are provided to fix an outer ring 29 of a radial rolling bearing 28 that rotatably supports an output shaft portion 25 of the output member 4.

[0050] The pressed member 2 is supported and fixed to the fixed portion by threading a bolt inserted into a through hole provided in the fixed portion into a screw hole 17 opening on the other axial side of the pressed member 2.

[0051] The input member 3 has an input-side engaging portion 18 arranged radially inside the pressed surface 8 and is arranged coaxially with the pressed surface 8. The input member 3 is connected to an input-side mechanism such as an electric motor, and rotational torque is input to the input member 3. The input member 3 may be formed by an output shaft of the input-side mechanism, or the input member 3 may be formed as a separate member from the output shaft and fixed coaxially to the output shaft. Additionally, an input shaft portion 20 provided on the input member 3 may be rotatably supported by the fixed portion. In this example, the input member 3 is formed as a separate member from the output shaft and includes an input shaft portion 20 having a substantially cylindrical shape, which is fixed coaxially to the tip of the output shaft of the electric motor.

[0052] The input-side engaging portion 18 is provided at a portion radially outwardly offset from the rotation center axis O of the input member 3, and is disposed at a position where it can engage with the input-side engaged portion 35 of the engaging element 5. The input-side engaging portion 18 is configured so that its radially inner surface 19 engages, specifically comes into contact with, the radially inner surface 40 of the input-side engaged portion 35 as the input member 3 or the engaging element 5 rotates. In this example, the input-side engaging portion 18 is provided so as to protrude toward the other axial side from a portion of the end face on the other axial side of the input shaft portion 20 that is radially outwardly offset from the rotation center axis O.

[0053] The shape of the input-side engaging portion 18 is not limited as long as it is configured to engage with the input-side engaged portion 35 of the engaging element 5. For example, the input-side engaging portion 18 may have a circular end face shape, a circumferentially symmetric end face shape, or an end face shape that is asymmetric with respect to the circumferential direction. In this example, the input-side engaging portion 18 has a circumferentially symmetric end face shape.

[0054] For example, the input-side engaging portion 18 may have an end face shape similar to a partial ring shape or a trapezoid whose circumferential width increases radially outward when viewed from the axial direction. In this example, the circumferential middle portion of the radially inner surface 19 of the input-side engaging portion 18 is formed by a flat surface perpendicular to the line connecting the rotation axis O and the center of the input-side engaging portion 18 when viewed from the axial direction, and the circumferential side portions are formed by a partial cylindrical convex surface that slopes radially outward toward both circumferential sides. The radially outer surface 21 of the input-side engaging portion 18 is formed by a partial cylindrical convex surface centered on the rotation axis O.

[0055] The number of input side engaging portions 18 is determined according to the number of engagers 5, and when the engager 5 is made up of a plurality of engagers 5, the input side engaging portion 18 is also made up of a plurality of input side engaging portions 18. In the reverse input disconnect clutch 1 of this example, the engager 5 is made up of two engagers 5. Therefore, the input side engaging portion 18 is made up of two input side engaging portions 18 to match the number of engagers 5. The two input side engaging portions 18 are arranged at two radially opposite positions on the radially outer side of the end face on the other axial side of the input shaft portion 20, and are spaced apart from each other in the radial direction of the input member 3.

[0056] The output member 4 has an output-side engaging portion 22 that is arranged radially inward of the input-side engaging portion 18, and is arranged coaxially with the pressed surface 8. The output member 4 is also arranged coaxially with the input member 3, radially inward of the pressed surface 8.

[0057] The output member 4 is connected to an output mechanism such as a reduction gear mechanism, and is configured to output rotational torque to the output mechanism as it rotates. The output member 4 may be configured as an input shaft of the output mechanism, or the output member 4 may be configured as a separate member from the input shaft and fixed coaxially to the input shaft.

[0058] The output side engaging portion 22 has a portion that can engage with the output side engaged portion 36 of the engaging element 5, and this engageable portion is located radially inward of the input side engaging portion 18 and radially outward from the rotation center axis O of the output member 4, and is arranged at a position where it can engage with the output side engaged portion 36 of the engaging element 5. The output side engaging portion 22 is configured so that this portion engages with, or more specifically comes into contact with, the output side engaged portion 36 as the output member 4 or the engaging element 5 rotates.

[0059] The shape of the output side engaging portion 22 is not limited as long as it has a portion that can engage with the output side engaged portion 36 of the engaging element 5 .

[0060] The output-side engaging portion 22 has a cam function. That is, the distance from the rotational center axis O of the output member 4 to the outer circumferential surface of the output-side engaging portion 22, which is the portion that engages with the output-side engaged portion 36, is not constant in the circumferential direction.

[0061] The number of portions of the output side engaging portion 22 that engage with the output side engaged portions 36 is determined according to the number of engaging elements 5, and when the engaging elements 5 are composed of a plurality of engaging elements 5, the output side engaging portion 22 is also configured to have a plurality of the engaging portions. In this example, the output side engaging portion 22 is configured to have portions that engage with two of the output side engaged portions 36, matching the number of engaging elements 5. However, even when the number of engaging elements 5 is one, it is possible to adopt a structure similar to this example.

[0062] The cross-sectional shape of the output side engaging portion 22 when cut along an imaginary plane perpendicular to the rotation center axis O of the output member 4 can be any shape as long as the output side engaging portion 22 has a cam function, and can be, for example, a quadrangle such as a square, rectangle, parallelogram, or trapezoid, an oval, or a shape similar to these quadrangles or ovals.

[0063] In this example, the output-side engaging portion 22 has a cross-sectional shape of a rounded rectangle when cut along an imaginary plane perpendicular to the central axis O of rotation of the output member 4, as shown in Fig. 7. More specifically, the outer circumferential surface of the output-side engaging portion 22 is composed of two parallel flat surfaces 23 and two partially cylindrical convex surfaces 24.

[0064] In this example, the output-side engaging portion 22 is plane-symmetrical with respect to an imaginary plane that passes through the rotational center axis O of the output member 4 and is parallel to the short-side direction. Furthermore, the output-side engaging portion 22 is plane-symmetrical with respect to an imaginary plane that passes through the rotational center axis O of the output member 4 and is parallel to the longitudinal direction. In other words, the output-side engaging portion 22 has a shape that is two-fold symmetrical with respect to the central axis of the output member 4. The output-side engaging portion 22 is disposed radially inward of the two input-side engaging portions 18 and between the output-side engaged portions 36 of the two engaging elements 5.

[0065] In this example, the output member 4 is configured as a separate member from the input shaft of the output side mechanism, and has an output shaft portion 25 and a small diameter shaft portion 26 in addition to the output side engagement portion 22.

[0066] The output shaft portion 25 has a stepped cylindrical shape and is provided adjacent to the other axial side of the output side engaging portion 22. The output side engaging portion 22 protrudes toward one axial side from the center of one axial end face of the output shaft portion 25. The output shaft portion 25 has an output flange portion 27 that protrudes radially outward from the end portion on one axial side over the entire circumference.

[0067] The small diameter shaft portion 26 protrudes axially from the center of an end surface on one axial side of the output side engaging portion 22. The small diameter shaft portion 26 has a cylindrical shape.

[0068] The output member 4 can be rotatably supported on the pressed member 2 or the fixed portion. In this example, the output member 4 is rotatably supported radially inside the pressed member 2 by a radial rolling bearing 28. The outer ring 29 of the radial rolling bearing 28 is fitted securely into the small-diameter cylindrical surface portion 10 of the pressed member 2 and is axially sandwiched between a side surface on one axial side of the inward flange portion 16 and a segmented annular retaining ring 32a engaged with one axial end of the small-diameter cylindrical surface portion 10. The inner ring 30 of the radial rolling bearing 28 is fitted securely onto the outer surface of one axial end of the output shaft portion 25 and is axially sandwiched between a side surface on the other axial side of the output flange portion 27 and a segmented annular retaining ring 32b engaged with the outer peripheral surface of an axially intermediate portion of the output shaft portion 25.

[0069] In this example, the radial rolling bearing 28 is configured as a ball bearing that uses balls as the rolling elements 31. However, the radial rolling bearing for supporting the output member 4 can also be configured as a tapered roller bearing that uses tapered rollers as the rolling elements or a roller bearing that uses cylindrical rollers.

[0070] The small diameter shaft portion 26 of the output member 4 is supported by a sliding bearing (sleeve) 33 on the inside of the input shaft portion 20 of the input member 3 so as to be able to rotate freely relative to the input member 3. By adopting such a configuration, it becomes easier to ensure that the input member 3 and the output member 4 are coaxial.

[0071] The engaging element 5 has a pressing surface 34 facing the pressed surface 8, an input side engaged portion 35 engageable with the input side engaging portion 18, and an output side engaged portion 36 engageable with the output side engaging portion 22, and is arranged so as to be movable in the radial direction (first direction).

[0072] When a rotational torque is input to the input member 3, the engaging element 5 moves away from the pressed surface 8 based on the engagement of the input side engaging portion 18 with the input side engaged portion 35, and engages the output side engaged portion 36 with the output side engaging portion 22, thereby transmitting the rotational torque input to the input member 3 to the output member 4. Conversely, when a rotational torque is input in the reverse direction to the output member 4, the engaging element 5 moves closer to the pressed surface 8 based on the engagement of the output side engaging portion 22 with the output side engaged portion 36, and presses the pressing surface 34 against the pressed surface 8, thereby frictionally engaging the pressing surface 34 with the pressed surface 8.

[0073] The engagement element 5 further has a release engagement portion 37 disposed radially inside the release ring 6. The release engagement portion 37 cooperates with the release ring 6 and the diameter expansion member 7 to switch the function of the engagement element 5, i.e., the reverse input cut-off function of the reverse input cut-off clutch 1, between enabled and disabled.

[0074] As shown in Figures 2, 3(a) and 3(b), the insertion portion 15 of the diameter-expanding member 7 is inserted into the discontinuous portion 43 of the release ring 6, and the circumferential width of the discontinuous portion 43 is elastically expanded, thereby expanding the diameter of the release ring 6.In this first state of the release ring 6, the release engagement portion 37 does not contact the inner peripheral surface 62 of the release ring 6 even when the pressing surface 34 is pressed against the pressed surface 8.When a rotational torque is input in reverse to the output member 4, the engagement element 5 can press the pressing surface 34 against the pressed surface 8, causing the pressing surface 34 to frictionally engage with the pressed surface 8.

[0075] 4(a) and 4(b), in the second state of the release ring 6, in which the engagement between the discontinuous portion 43 of the release ring 6 and the insertion portion 15 of the diameter expansion member 7 is released and the release ring 6 elastically restores its original size and thereby reduces its diameter, the engagement between the inner circumferential surface 62 of the release ring 6 and the release engagement portion 37 moves the engagement element 5 away from the pressed surface 8, preventing the pressing surface 34 from being pressed against the pressed surface 8. Therefore, the engagement element 5 can transmit torque between the input member 3 and the output member 4, regardless of the direction of torque transmission between the input member 3 and the output member 4.

[0076] In this example, the engaging element 5 has an end face shape similar to a semicircle when viewed from the axial direction, and has a shape that is symmetrical with respect to the width direction.

[0077] The pressing surface 34 is provided on the radially outer surface of the engaging element 5 that faces the pressed surface 8. The pressing surface 34 can be configured from all or part of the radially outer surface of the engaging element 5. The number of pressing surfaces 34 can be any number equal to or greater than one. In this example, the pressing surface 34 is configured from two pressing surfaces 34 provided on the radially outer surface of the engaging element 5 at two positions that are spaced apart from each other in the circumferential direction. Each pressing surface 34 is configured from a partially cylindrical convex curved surface having a radius of curvature that is smaller than the radius of curvature of the pressed surface 8.

[0078] When viewed from the axial direction, the portion of the radially outer surface of the engaging element 5 that is circumferentially offset from the two pressing surfaces 34 is located radially inward of an imaginary circle that is centered on the rotational center axis O of the input member 3 and that is tangent to the two pressing surfaces 34. In other words, when the two pressing surfaces 34 are in contact with the pressed surface 8, the portion that is circumferentially offset from the two pressing surfaces 34 does not come into contact with the pressed surface 8.

[0079] The pressing surface 34 preferably has a surface property that gives it a higher coefficient of friction with the pressed surface 8 than other parts of the engaging element 5. The pressing surface 34 may also be formed of a surface of a friction material fixed by adhesive or the like to the radially outer surface of the engaging element 5 or other parts.

[0080] The shape and arrangement of the input-side engaged portion 35 are not limited as long as it is configured to be able to engage with the input-side engaging portion 18 and move the engaging element 5 away from the pressed surface 8 as the input member 3 rotates. The input-side engaged portion 35 is located at the widthwise intermediate portion of the engaging element 5, and is configured by a radial recess provided in a portion of the radial outer surface of the engaging element 5 that is away from the pressing surface 34, an axial through-hole or axial recess provided in the radial intermediate portion of the engaging element 5, or the like.

[0081] In this example, the input-side engaged portion 35 is provided in a radially intermediate portion of the widthwise center of the engaging element 5. When viewed from the axial direction, the input-side engaged portion 35 has an opening shape similar to an oval that is elongated in the widthwise direction of the engaging element 5, and is configured as a through-hole that passes through a radially intermediate portion of the widthwise center of the engaging element 5 in the axial direction.

[0082] The input-side engaged portion 35 has a size that allows the input-side engaging portion 18 to be loosely inserted therein. Therefore, with the input-side engaging portion 18 inserted inside the input-side engaged portion 35, there is a gap between the input-side engaging portion 18 and the inner surface of the input-side engaged portion 35 in both the width direction and the radial direction of the engaging element 5. Therefore, the input-side engaging portion 18 is displaceable relative to the input-side engaged portion 35 in the rotational direction of the input member 3, and the input-side engaged portion 35 is displaceable in the radial direction of the engaging element 5 relative to the input-side engaged portion 18. In this example, of the inner surface of the input-side engaged portion 35, a radially inner surface 40 facing radially outward is formed by a flat surface perpendicular to the first direction.

[0083] There are no limitations on the shape and arrangement of the output-side engaged portion 36, as long as it is configured to be able to engage with the output-side engaging portion 22 as the output member 4 rotates and move the engaging element 5 so as to approach the pressed surface 8. The output-side engaged portion 36 is located at the middle portion of the engaging element 5 in the width direction, and is configured by the radially inner surface of the engaging element 5, a radially recessed portion provided on the radially inner surface, etc.

[0084] In this example, the output-side engaged portion 36 is provided in the widthwise center of the radially inner surface of the engaging element 5, which is the side surface opposite the pressed surface 8 in the first direction. The engaging element 5 has a flat surface portion 41 on its radially inner surface that is perpendicular to the radial direction of the engaging element 5, and the flat surface portion 41 has two protrusions 42 that protrude radially inward at two positions in the width direction of the engaging element 5. The output-side engaged portion 36 is formed by a portion of the flat surface portion 41 that is located between the two protrusions 42 in the width direction. The widthwise dimension of the output-side engaged portion 36, i.e., the distance between the two protrusions 42, is larger than the widthwise dimension of the flat surface 23 of the output-side engaging portion 22.

[0085] The number and shape of the release engagement portions 37 are not limited as long as they are configured so as to be out of contact with the inner surface 62 of the release ring 6 in the first state of the release ring 6 (see Figures 2, 3(a) and 3(b)), and to be engaged with the inner surface 62 of the release ring 6 in the second state of the release ring 6 (see Figures 4(a) and 4(b)), thereby preventing the pressing surface 34 from being pressed against the pressed surface 8.

[0086] In this example, the release engagement portions 37 are configured by two release engagement portions 37 for each engagement piece 5. The two release engagement portions 37 are provided so as to protrude axially to one side from both widthwise sides of the radially outer portion of one axial side of the engagement piece 5. Each release engagement portion 37 can be configured integrally with the other portion of the engagement piece 5, or can be configured separately from the other portion of the engagement piece 5 and then joined and fixed to the other portion by a method such as adhesive bonding, welding, or screwing. In this example, each release engagement portion 37 is configured separately from the other portion of the engagement piece 5 and then joined and fixed.

[0087] In this example, each release engagement portion 37 has a partially annular shape or a similar shape extending in the circumferential direction when viewed from the axial direction. However, each release engagement portion may have a columnar shape, such as a cylindrical shape extending in the axial direction. For example, a release engagement portion having such a shape may be formed by a pin whose axial end is press-fitted into a press-fit hole formed in the engagement element, or by the head of a bolt whose shank is threaded into a threaded hole formed in the engagement element. In this case, the bearing surface of the bolt head can abut against the side surface of the engagement element. The bolt head may also have a hexagonal hole for engaging a hexagonal wrench, and the outer peripheral surface that engages with the inner peripheral surface 62 of the release ring 6 may be cylindrical.

[0088] In this example, each release engagement portion 37 has a protrusion 39 that protrudes radially outward at a portion (the tip of the release engagement portion 37) that is located farther from the engagement element 5 in the axial direction than the portion that engages with the inner circumferential surface 62 of the release ring 6. The protrusion 39 has the function of preventing the release ring 6 from falling off in the axial direction from the radially outer side of the release engagement portion 37 when the release ring 6 is in the second state, and the shape of the protrusion 39 is not limited as long as it is configured to have such a function. However, the protrusion 39 may be omitted.

[0089] In this example, each release engagement portion 37 has an axial width dimension greater than the axial width dimension of the release ring 6 and has a protrusion 39 protruding radially outward at one axial end. In the second state of the release ring 6, the inner circumferential surface 62 of the release ring 6 engages with an engagement surface 63 provided on the radially outer surface of a portion of each release engagement portion 37 located on the other axial side of the protrusion 39 (the intermediate portion and base end portion of the release engagement portion 37). When the inner circumferential surface 62 of the release ring 6 engages with the engagement surface 63 of each release engagement portion 37, the protrusion 39 faces the side surface on one axial side of the release ring 6, thereby preventing the release ring 6 from moving to one axial side. When the present disclosure is implemented, each release engagement portion 37 can be shaped like a bolt, the tip of whose shaft is screwed into a threaded hole formed in an engagement element. In this case, the radially outer surface of the shaft portion other than the tip portion can be made to engage with the inner peripheral surface 62 of the release ring 6. In addition, the head of the bolt can also function as the protrusion 39.

[0090] The protrusion 39 is provided so that its radially outer end does not protrude radially outward beyond the pressing surface 34. In this example, the diameter of a circumscribing circle of the protrusion 39 of the release engagement portion 37, centered on the central axis O of the pressed surface 8, when the pressing surface 34 of the engagement portion 5 is pressed against the pressed surface 8, is smaller than the inner diameter of the release ring 6 in the first state. However, the diameter of a circumscribing circle of the protrusion 39 of the release engagement portion 37, centered on the central axis O of the pressed surface 8, when the pressing surface 34 of the engagement portion 5 is pressed against the pressed surface 8, may also be larger than the inner diameter of the release ring 6 in the first state.

[0091] The engaging element 5 can be integrally formed as a whole, i.e., formed from a single part, or can be formed by combining a plurality of parts. In this example, the engaging element 5 is formed by joining and fixing a release engaging portion 37 to an engaging element main body 38 having a pressing surface 34, an input-side engaged portion 35, and an output-side engaged portion 36 so as to protrude in the axial direction from one axial side surface of the engaging element main body 38.

[0092] As long as the engaging element 5 has the above-described configuration, it can be configured with one engaging element 5 or with multiple engaging elements 5 arranged at different positions in the circumferential direction. In this example, the engaging element 5 is configured with two engaging elements 5 arranged at positions sandwiching the central axis of the pressed surface 8 from both sides in the radial direction. Each engaging element 5 has the function of an engaging element 5.

[0093] In the reverse input cutoff clutch 1 of this example, the pressing surfaces 34 of the two engaging elements 5 face radially opposite each other, and the flat surface portions 41 face each other, with each engaging element 5 disposed radially inward of the pressed surface 8 so as to be movable in the first direction. Furthermore, the two input-side engaging portions 18 of the input member 3 disposed on one axial side are axially inserted into the input-side engaged portions 35 of the two engaging elements 5, and the output-side engaging portion 22 of the output member 4 disposed on the other axial side is axially inserted between the output-side engaged portions 36 of the two engaging elements 5. In other words, the two engaging elements 5 are disposed so that the output-side engaging portion 22 is sandwiched from both radial sides by the respective output-side engaged portions 36.

[0094] When the two engaging elements 5 are positioned radially inside the pressed surface 8, the inner diameter dimension of the pressed surface 8 and the radial dimension of the engaging elements 5 are regulated so that a gap exists in at least one of the areas between the pressed surface 8 and the pressing surface 34, the area between the output side engaging portion 22 and the output side engaged portion 36, and the area between the tip faces of the convex portions 42.

[0095] In this example, when the two engaging elements 5 are positioned radially inward of the pressed surface 8, the portions of the release engaging portion 37 provided on each engaging element 5 excluding the protruding portion 39 (the middle portion and base end portion of the release engaging portion 37) are positioned so as to radially overlap the circumferential groove 12.

[0096] The release ring 6 is configured in a segmented annular shape having an inner circumferential surface 62 and a discontinuous portion 43 at one location in the circumferential direction.

[0097] The release ring 6 is switchable between a first state in which the insert portion 15 of the diameter-expanding member 7 is inserted into the discontinuous portion 43, elastically expanding the circumferential width of the discontinuous portion 43, thereby expanding the diameter thereof, and the release engagement portion 37 does not come into contact with the inner peripheral surface 62 even when the pressing surface 34 is pressed against the pressed surface 8, and a second state in which the engagement between the discontinuous portion 43 and the insert portion 15 is released and the ring is reduced in diameter by elastically restoring itself, and the engagement between the inner peripheral surface 62 and the release engagement portion 37 prevents the pressing surface 34 from being pressed against the pressed surface 8.

[0098] In the normal use state of the reverse input cutoff clutch 1 after the reverse input cutoff clutch 1 is installed in the middle of the torque transmission path of a mechanical device, the release ring 6 is switched to the first state. In this state, the reverse input cutoff function of the reverse input cutoff clutch 1 is enabled.

[0099] On the other hand, if a fault occurs in the input side mechanism such as the electric motor, the release ring 6 is switched to the second state. In this state, the reverse input cutoff clutch 1 switches its reverse input cutoff function to disabled state, and the input member 3, output member 4, engaging element 5 and release ring 6 rotate together, enabling torque to be transmitted from the output member 4 to the input member 3. This makes it possible to change the position, posture, etc. of the driven member connected to the output member 4.

[0100] As long as it functions as described above, the material and specific shape of the release ring 6 in the reverse input cutoff clutch 1 are arbitrary. Materials that can be used to form the release ring 6 include elastic metal materials such as spring steel, as well as elastic synthetic resins.

[0101] The release ring 6 may have any cross-sectional shape when cut along an imaginary plane including its central axis, and may have a cross-sectional shape such as a square, rectangle, circle, ellipse, trapezoid, etc. In this example, the release ring 6 has a rectangular cross-sectional shape.

[0102] In a free state, the release ring 6 has an inner diameter that is smaller than the diameter of a circumscribing circle of the engagement surface 63 of the release engagement portion 37, the center of which is the central axis O of the pressed surface 8, when the pressing surface 34 of the engagement piece 5 is pressed against the pressed surface 8. Therefore, when the insertion portion 15 of the diameter-expanding member 7 is pulled out of the discontinuous portion 43, the release ring 6 releases the engagement between the discontinuous portion 43 and the insertion portion 15 and elastically contracts, causing the inner circumferential surface 62 to press the engagement surface 63 of the release engagement portion 37 radially inward, thereby moving the engagement piece 5 radially inward and switching to a state in which the pressing surface 34 can be prevented from being pressed against the pressed surface 8, i.e., the second state.

[0103] 3(a) and 3(b), the relationship between the outer diameter of the releasing ring 6 and the inner diameter of the portion of the pressed member 2 that radially overlaps with the releasing ring 6 (in this example, the bottom surface of the circumferential groove 12) is arbitrary as long as it enables the reverse input blocking function of the reverse input blocking clutch 1 to be effective. That is, the outer diameter can be made smaller than the inner diameter, or the outer diameter can be made equal to the inner diameter so that the outer peripheral surface of the releasing ring 6 is pressed against the inner peripheral surface of the pressed member 2 or is in contact with it without being pressed against it.

[0104] In this example, the outer diameter of the releasing ring 6 in the first state is slightly smaller than the inner diameter of the portion of the pressed member 2 that radially overlaps with the releasing ring 6 (the bottom surface of the circumferential groove 12). If the outer diameter is made equal to the inner diameter and a configuration is adopted in which the outer peripheral surface of the releasing ring 6 is pressed against the inner peripheral surface of the pressed member 2, the axial movement of the releasing ring 6 can be restricted based on the frictional force acting on the contact portion between the outer peripheral surface of the releasing ring 6 and the inner peripheral surface of the pressed member 2. Including such a case, if the axial movement of the releasing ring 6 in the first state can be restricted, the circumferential groove 12 can be omitted.

[0105] The relationship between the inner diameter of the release ring 6 in the second state shown in FIGS. 4(a) and 4(b) and the inner diameter of the release ring 6 in the free state can be any as long as it can disable the reverse input blocking function of the reverse input blocking clutch 1. In this example, the release ring 6 in the second state elastically expands in diameter compared to the free state. Therefore, when the release ring 6 is switched to the second state, the output-side engaged portion 36 of each engagement element 5 is pressed against the flat surface 23 of the output-side engaging portion 22 by the elastic force of the release ring 6. However, it is also possible to adopt a configuration in which the release ring 6 is in the free state in the second state, i.e., when the release ring 6 is switched to the second state, the output-side engaged portion 36 of each engagement element 5 is in contact with the flat surface 23 of the output-side engaging portion 22 without being pressed against it, or a configuration in which a gap remains between the output-side engaged portion 36 of each engagement element 5 and the flat surface 23 of the output-side engaging portion 22.

[0106] In this example, the outer diameter of the releasing ring 6 in the second state is smaller than the diameter of the radially inner opening of the circumferential groove 12 of the pressed member 2. Therefore, the releasing ring 6 is in a state of coming out of the circumferential groove 12 in the second state.

[0107] In this example, at least a rear portion of the discontinuous portion 43 of the release ring 6 in the insertion direction of the insertion portion 15 relative to the discontinuous portion 43 has a circumferential width that increases toward the rear in the insertion direction. Such a shape of the discontinuous portion 43 is provided to make it easier to insert the insertion portion 15 into the discontinuous portion 43. In this example, the insertion portion 15 is inserted into the discontinuous portion 43 from the radially inner side toward the radially outer side, and therefore the rear side of the insertion direction of the insertion portion 15 relative to the discontinuous portion 43 is the radially inner side.

[0108] Specifically, in this example, the radially outer half of the end faces on both sides of the circumferential direction of the releasing ring 6 is, in a free state, made up of flat surface portions 44 that exist within an imaginary plane including the central axis of the releasing ring 6 or an imaginary plane approximately parallel to this, and the radially inner half of the end faces on both sides of the circumferential direction of the releasing ring 6 is made up of concave-side inclined surface portions 45 that are inclined in a direction such that the circumferential width of the discontinuous portion 43 increases as it goes radially inward. In this example, the concave-side inclined surface portions 45 are made up of flat surfaces.

[0109] The release ring 6 is disposed radially outward of the release engagement portions 37 of the respective engagement elements 5. In the normal use state of the reverse input cutoff clutch 1, the release ring 6 is switched to the first state, and in this example, in this state, the release ring 6 enters the circumferential groove 12 and its axial position is restricted.

[0110] The diameter expanding member 7 has an insertion portion 15 that is inserted into the discontinuous portion 43 of the release ring 6. The diameter expanding member 7 can be composed of only the insertion portion 15, but it is preferable that the diameter expanding member 7 further has a structure that allows the insertion portion 15 to be inserted and removed in a predetermined direction.

[0111] Any material and shape may be used for the diameter expansion member 7. Materials that can be used to form the diameter expansion member 7 include metal materials such as iron-based alloys and light alloys, as well as synthetic resins.

[0112] The diameter expanding member 7 can be configured to be movable relative to the pressed member 2, or can be configured to be immovable relative to the pressed member 2.

[0113] In this example, the diameter expanding member 7 is configured to be able to move relative to the pressed member 2, and to be able to insert and remove the insertion portion 15 into and from the discontinuous portion 43 based on this movement.

[0114] The direction in which the insertion portion 15 is inserted into or removed from the discontinuous portion 43 is also arbitrary, and the insertion / removal direction may be, for example, the radial direction or the axial direction. In this example, the insertion portion 15 is inserted into the discontinuous portion 43 from the radially inner side to the radially outer side, and is removed from the radially outer side to the radially inner side.

[0115] In this example, at least a front portion of the insertion portion 15 in the insertion direction of the insertion portion 15 relative to the discontinuous portion 43 has a circumferential width that decreases toward the front in the insertion direction. This shape of the insertion portion 15 is provided to make it easier to insert the insertion portion 15 into the discontinuous portion 43. In this example, the insertion portion 15 is inserted into the discontinuous portion 43 from the radially inner side toward the radially outer side, and therefore the front side of the insertion direction of the insertion portion 15 relative to the discontinuous portion 43 is the radially outer side.

[0116] Specifically, in this example, the insertion portion 15 has a hexagonal or hexagon-like shape when viewed in the axial direction. The circumferential width of the insertion portion 15 is constant in the rear half (radially inner) of the insertion direction relative to the discontinuous portion 43, and decreases toward the front in the insertion direction in the front half (radially outer) of the insertion direction relative to the discontinuous portion 43. That is, the insertion portion 15 has a pair of convex inclined surface portions 46 on both circumferential side surfaces of the front half in the insertion direction that are inclined toward each other toward the front in the insertion direction.

[0117] In this example, each of the pair of convex inclined surface portions 46 includes a front convex curved surface portion 47 that forms the front (radially outer) end portion in the insertion direction relative to the discontinuous portion 43, a rear convex curved surface portion 48 that forms the rear (radially inner) end portion in the insertion direction relative to the discontinuous portion 43, and a concave curved surface portion 49 that connects the front convex curved surface portion 47 and the rear convex curved surface portion 48. The front convex curved surface portion 47 and the rear convex curved surface portion 48 are each formed by a partially cylindrical convex surface. The concave curved surface portion 49 is formed by a partially cylindrical concave surface that smoothly connects the front convex curved surface portion 47 and the rear convex curved surface portion 48. However, each of the convex inclined surface portions 46 may also be formed by a flat surface.

[0118] In this example, when the release ring 6 is in its free state, as shown in Figure 5(a), the shape and dimensions of the pair of concave-side inclined surface portions 45 and the pair of convex-side inclined surface portions 46 are regulated so that the radially outer end of the insertion portion 15 can be inserted between a pair of concave-side inclined surface portions 45 provided on the radially inner half of the end faces on both circumferential sides of the release ring 6, and the front convex curved surface portions 47 of the pair of convex-side inclined surface portions 46 can be brought into contact with the pair of concave-side inclined surface portions 45.

[0119] In this example, in addition to the insertion portion 15, the expanding member 7 has a pillar portion 50 as a structure for supporting the insertion portion 15 and enabling the insertion portion 15 to be inserted into and removed from the discontinuous portion 43.

[0120] The column portion 50 is arranged to extend in the insertion / removal direction of the insertion portion 15, i.e., in the radial direction, and has a rectangular cross-sectional shape when cut along an imaginary plane perpendicular to the extension direction (radial direction).

[0121] The insertion portion 15 is provided so as to protrude from the radially inner end of the column portion 50 toward the other axial side.

[0122] The diameter expanding member 7 is supported so as to be capable of linear movement only in the radial direction relative to the pressed member 2 by inserting the pillar portion 50 into the diameter expanding member guide portion 13 of the pressed member 2 without any rattle.

[0123] In the normal use state of the reverse input cutoff clutch 1, the release ring 6 is switched to the first state by inserting the insertion portion 15 into the discontinuous portion 43 from the radially inner side toward the radially outer side as shown in the order of Figures 5(a) to 5(c) based on the linear movement of the diameter expansion member 7 in the radial direction.

[0124] In this example, as shown in the order of FIGS. 5( a) to 5(c), in the process of inserting the insertion portion 15 into the discontinuous portion 43 from the radially inner side toward the radially outer side, first, as shown in FIG. 5(a), only the front convex curved surface portions 47 of the pair of convex-side inclined surface portions 46 come into contact with the pair of concave-side inclined surface portions 45. Next, as shown in FIG. 5(b), both the front convex curved surface portions 47 and the rear convex curved surface portion 48 of the pair of convex-side inclined surface portions 46 come into contact with the pair of concave-side inclined surface portions 45. Next, only the rear convex curved surface portions 48 of the pair of convex-side inclined surface portions 46 come into contact with the pair of concave-side inclined surface portions 45. Furthermore, as shown in FIG. 5(c), a portion of the insertion portion 15 located rearward (radially inner) in the insertion direction than the pair of convex-side inclined surface portions 46 is pushed between the pair of flat surface portions 44, whereby the release ring 6 is switched to the first state.

[0125] When the release ring 6 is switched to the first state or the second state, the radial position of the diameter expansion member 7 relative to the pressed member 2 can be maintained by any method. In this example, the radial position of the diameter expansion member 7 relative to the pressed member 2 is maintained by a retention mechanism including a retention member such as a clip (not shown) attached to the radially outer end of the pillar portion 50. However, the radial position of the diameter expansion member 7 relative to the pressed member 2 can also be maintained by, for example, frictional force acting between the outer peripheral surface of the pillar portion 50 and the inner peripheral surface of the diameter expansion member guide portion 13.

[0126] The reverse input cutoff clutch 1 of this example further includes a biasing member 51 as an optional component.

[0127] The biasing member 51 elastically biases the engaging element 5 in a direction to bring it closer to the pressed surface 8. The biasing member 51 can be made of a spring such as a leaf spring, a coil spring, or a disc spring, or an elastic material such as rubber, elastomer, or synthetic resin. The number of biasing members 51 is not particularly limited and is determined appropriately depending on the number and arrangement of the engaging elements 5.

[0128] In this example, the biasing member 51 is composed of two biasing members 51 arranged at two positions in the width direction between the radially inner surfaces of the two engaging members 5, and each biasing member 51 is composed of a compression coil spring. A protrusion 42 is inserted into the inside of each biasing member 51 at both ends in the extension direction. This prevents each biasing member 51 from falling off from between the two engaging members 5.

[0129] The two biasing members 51 elastically bias the two engagement elements 5 in a direction that brings them closer to the pressed surface 8 by the force that attempts to elastically restore the original shape. As a result, in a 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 engagement elements 5 are in contact with the pressed surface 8.

[0130] The reverse input disconnecting clutch 1 of this example further includes two spacers 52 and a stopper member 53 as optional components.

[0131] Each spacer 52 has the function of regulating the axial position of the engaging element 5 relative to the output member 4.

[0132] In this example, each spacer 52 is formed in a flat plate shape and has a substantially rectangular end face shape when viewed in the axial direction. Each spacer 52 has a through hole 54 through which the output side engaging portion 22 can be inserted without rattle. Each spacer 52 is arranged on both axial sides of the two engaging elements 5 with the output side engaging portion 22 inserted into the through hole 54 without rattle.

[0133] The stopper member 53 has a function of preventing the spacer 52 on one axial side of the two spacers 52 from moving to one axial side and falling off the output member 4.

[0134] In this example, the stopper member 53 is configured as a snap ring having a partially cut-out annular shape. The stopper member 53 is engaged with the other axial end of the small diameter shaft portion 26.

[0135] <Explanation of reverse input cutoff clutch operation> The operation of the reverse input cutoff clutch 1 when the reverse input cutoff function is enabled, i.e., when the release ring 6 is switched to the first state, will be described with reference to Figures 8 and 9. Note that Figures 8 and 9 omit the biasing member 51 and exaggerate the radial gaps between the input member 3 and the output member 4 and the two engaging elements 5.

[0136] When a rotational torque is input to the input member 3, the engaging element 5 moves in a direction away from the pressed surface 8, regardless of the rotational direction of the input member 3. Then, the rotational torque input to the input member 3 is transmitted to the output member 4 via the engaging element 5.

[0137] That is, when a rotational torque is input to the input member 3, the input-side engaging portion 18 rotates inside the input-side engaged portion 35 in the rotation direction of the input member 3 (counterclockwise in the example of FIG. 8 ), as shown in FIG. 8 . This reduces the gap between the radially inner surface 19 of the input-side engaging portion 18 and the radially inner surface 40 of the input-side engaged portion 35, and causes the radially inner surface 19 of the input-side engaging portion 18 to come into contact with the radially inner surface 40 of the input-side engaged portion 35.

[0138] When the input member 3 rotates further from this state, the radially inner surface 19 of the input-side engaging portion 18 presses the radially inner surface 40 of the input-side engaged portion 35 radially inward, and the engaging element 5 moves in a direction away from the pressed surface 8. That is, the engaging element 5 moves radially inward based on engagement with the input member 3, and the output-side engaged portion 36 of the engaging element 5 engages with the output-side engaging portion 22 of the output member 4. In this example, the radially inner surfaces of the two engaging elements 5 approach each other, and the output-side engaged portions 36 of the two engaging elements 5 clamp the output-side engaging portion 22 of the output member 4 from both radial sides.

[0139] More specifically, when the output-side engaged portion 36 of the engager 5 engages with the output-side engaging portion 22, the output member 4 rotates so that the flat surface 23 of the output-side engaging portion 22 is parallel to the output-side engaged portion 36 of the engager 5, bringing the flat surface 23 into contact with the output-side engaged portion 36 without any rattle. As a result, the rotational torque input to the input member 3 is transmitted to the output member 4 via the engager 5 and output from the output member 4.

[0140] When a rotational torque is reversely input to the output member 4, the engaging element 5 moves in a direction approaching the pressed surface 8, regardless of the rotational direction of the output member 4. Then, the rotational torque reversely input to the output member 4 is completely blocked and not transmitted to the input member 3, or only a portion of the rotational torque reversely input to the output member 4 is transmitted to the input member 3, with the remainder blocked.

[0141] 9, the output-side engaging portion 22 rotates relative to the engaging element 5 in the rotation direction of the output member 4 (clockwise in the example of FIG. 9). The output-side engaged portion 36 is pressed radially outward by the connection (corner) between the flat surface 23 and the convex curved surface 24 on the outer circumferential surface of the output-side engaging portion 22, and the engaging element 5 moves in a direction approaching the pressed surface 8.

[0142] That is, the engaging element 5 moves radially outward based on the engagement with the output member 4, and the pressing surfaces 34 of the engaging element 5 come into contact with the pressed surface 8 and frictionally engage with the pressed surface 8. In this example, the two engaging elements 5 move radially outward, i.e., in directions away from each other, based on the engagement with the output member 4, and the pressing surfaces 34 of the two engaging elements 5 come into contact with the pressed surface 8 and frictionally engage with the pressed surface 8.

[0143] As a result, the rotational torque input back to the output member 4 is either completely blocked and not transmitted to the input member 3, or only a portion of the rotational torque input back to the output member 4 is transmitted to the input member 3 and the remainder is blocked.

[0144] To completely block the rotational torque input in reverse to the output member 4 and prevent it from being transmitted to the input member 3, the engaging element 5 is clamped between the output side engaging portion 22 and the pressed member 2 so that the pressing surface 34 of the engaging element 5 does not slide against the pressed surface 8, thereby locking the output member 4.

[0145] In order to transmit only a portion of the rotational torque input inversely to the output member 4 to the input member 3 and block the remainder, the engaging element 5 is clamped between the output side engaging portion 22 and the pressed member 2 so that the pressing surface 34 of the engaging element 5 slides against the pressed surface 8, thereby semi-locking the output member 4.

[0146] In the reverse input cutoff clutch 1 of this example, the size of the gap between each component is adjusted to enable the above operation. In particular, when the pressing surface 34 of the engaging element 5 is in contact with the pressed surface 8, a gap is set to exist between the radially inner surface 19 of the input side engaging portion 18 and the radially inner surface 40 of the input side engaged portion 35.

[0147] This prevents the input side engaging portion 18 from blocking the radially outward movement of the engaging element 5 when a rotational torque is input in reverse to the output member 4, and also ensures that even after the pressing surface 34 comes into contact with the pressed surface 8, the surface pressure acting on the contact point between the pressing surface 34 and the pressed surface 8 changes depending on the magnitude of the rotational torque input in reverse to the output member 4, thereby ensuring that the output member 4 is locked or semi-locked appropriately.

[0148] In the reverse input cutoff clutch 1 of this example, the biasing member 51 elastically biases the engaging element 5 in a direction that brings it closer to the pressed surface 8. This makes it possible to keep the pressing surface 34 of the engaging element 5 in contact with the pressed surface 8 except when rotational torque is input to the input member 3. Therefore, when rotational torque is reversely input to the output member 4, the surface pressure at the contact portion between the pressing surface 34 of the engaging element 5 and the pressed surface 8 is quickly increased, and the reverse input cutoff clutch 1 is switched to a locked or semi-locked state, i.e., good locking performance is ensured.

[0149] <Explanation of how to enable and disable the reverse input blocking function> The reverse input blocking function of the reverse input blocking clutch 1 can be switched between enabled and disabled by inserting and removing the insertion portion 15 of the diameter expansion member 7 into and from the discontinuous portion 43 of the release ring 6 using a tool or the like.

[0150] In this example, when switching the reverse input blocking function of the reverse input blocking clutch 1 from enabled to disabled, the holding mechanism for the diameter expansion member 7 is released, and then the diameter expansion member 7 is moved radially inward using a tool or the like to remove the insertion portion 15 radially inward from the discontinuous portion 43. This causes the release ring 6 to elastically restore its original shape and contract in diameter. Based on the engagement between the inner circumferential surface 62 of the release ring 6 and the portion of the release engagement portion 37 located on the other axial side of the protrusion 39, the engagement element 5 is moved radially inward against the elastic force of the biasing member 51. This switches the release ring 6 to the second state. When the release ring 6 is switched to the second state, the output-side engaged portion 36 engages with the output-side engaging portion 22, and the engagement element 5 is prevented from moving in a direction that brings the pressing surface 34 closer to the pressed surface 8. With the release ring 6 switched to the second state, the radial position of the diameter expanding member 7 is again held by the holding mechanism.

[0151] In this manner, when the reverse input blocking function of the reverse input blocking clutch 1 is switched to disabled, torque is transmitted between the input member 3 and the output member 4, regardless of the direction of torque transmission between the input member 3 and the output member 4. Specifically, when rotational torque is reverse input to the output member 4, the output side engaged portion 36 is pressed radially outward by the connection portion (corner portion) between the flat surface 23 and the convex curved surface 24 on the outer circumferential surface of the output side engaging portion 22, regardless of the rotational direction of the output member 4.

[0152] At this time, the engagement piece 5 is prevented from moving in a direction approaching the pressed surface 8 and frictionally engaging the pressing surface 34 with the pressed surface 8 because the inner peripheral surface 62 of the release ring 6 presses down the release engagement portion 37. As a result, the output member 4, engagement piece 5, and release ring 6 rotate integrally.

[0153] Furthermore, as the engaging element 5 rotates, the radially inner surface 40 of the input-side engaged portion 35 presses the radially inner surface 19 of the input-side engaging portion 18 in the circumferential direction, transmitting rotational torque to the input member 3. That is, in this state, the output member 4, engaging element 5, release ring 6, and input member 3 rotate integrally.

[0154] In this example, in order to prevent the insertion portion 15 from interfering with the release engagement portion 37 and the input side engagement portion 18, as shown in Figure 4(b), the insertion portion 15 is positioned radially outward from the circumscribing circle Ci of the input side engagement portion 18 centered on the rotation center axis O of the input member 3, and radially inward from the inscribing circle Co of the release engagement portion 37 centered on the rotation center axis O of the input member 3.

[0155] It is also possible to employ a configuration in which a stopper member is attached to or integrally formed with a portion of the column portion 50 of the diameter-expanding member 7 that is located radially outward from the outer peripheral surface of the pressed member 2, and with the stopper member in contact with the outer peripheral surface of the pressed member 2, the insertion portion 15 is positioned radially outward from the circumscribing circle Ci and radially inward from the inscribing circle Co.

[0156] According to the reverse input cutoff clutch 1 of this example, even after the reverse input cutoff clutch 1 is incorporated into the torque transmission path of a mechanical device, the reverse input cutoff function can be disabled by removing the insertion portion 15 of the expanding diameter member 7 from the discontinuous portion 43 of the release ring 6.

[0157] Therefore, for example, even if a malfunction occurs in the input side mechanism such as the drive source connected to the input member 3, making it impossible to input torque from the input member 3 to the reverse input blocking clutch 1 and making it impossible to change the position, posture, etc. of the driven member connected to the output member 4, the reverse input blocking function can be disabled to enable torque transmission from the output member 4 to the input member 3, i.e., by allowing the output member 4 to rotate due to torque input from the output member 4 side, the position and posture of the driven member can be changed by applying an external force to the driven member, thereby ensuring safety.

[0158] When the reverse input blocking function is disabled and a rotational torque is input to the input member 3, the rotational torque is transmitted to the output member 4 in the same manner as when the reverse input blocking function is enabled.

[0159] In this example, when the reverse input blocking function is switched back to enabled, the radial position of the diameter expansion member 7 is released from the holding mechanism, and then the diameter expansion member 7 is moved radially outward using a tool or the like, thereby inserting the insertion portion 15 into the discontinuous portion 43 from the radially inner side toward the radially outer side. This switches the release ring 6 to the first state. Then, with the release ring 6 switched to the first state, the radial position of the diameter expansion member 7 is again held by the holding mechanism.

[0160] [Example 2] A second example of the embodiment of the present disclosure will be described with reference to FIGS. 10(a) to 10(c).

[0161] The reverse input cutoff clutch of this example differs from the first example in that it includes a mechanism including a feed screw shaft 55 as a mechanism for moving the diameter expanding member 7a in the radial direction.

[0162] The feed screw shaft 55 has a feed screw portion 56 on its outer peripheral surface, and is supported by the pressed member 2a so as to be rotatable only. In this example, the feed screw shaft 55 is arranged to extend in the radial direction of the pressed surface 8. Specifically, the feed screw shaft 55 is arranged parallel to the column portion 50a of the diameter-expanding member 7a.

[0163] In this example, the pressed member 2a has a feed screw shaft support hole 57 that penetrates radially in a portion adjacent to one axial side of the diameter expansion member guide portion 13a. The feed screw shaft support hole 57 has a cylindrical inner circumferential surface. The interior of the diameter expansion member guide portion 13a and the interior of the feed screw shaft support hole 57 communicate with each other through a communication portion 58 that is provided over the entire radial length between the diameter expansion member guide portion 13a and the feed screw shaft support hole 57.

[0164] The radially inner end of the feed screw shaft 55 is rotatably and rattle-free inserted into the feed screw shaft support hole 57. The radially outer end of the feed screw shaft 55 is located radially outward of the column portion 50a of the diameter-expanding member 7a, and is supported by a support member such as a bearing so as to be only rotatable relative to a fixed portion such as a housing that supports and fixes the pressed member 2a.

[0165] In this example, the diameter expanding member 7a has rack teeth 59 that engage with the feed screw portion 56 and converts the rotation of the feed screw shaft 55 into radial movement of the member itself.

[0166] In this example, the rack teeth 59 are provided on the surface of the outer circumferential surface of the pillar portion 50a of the diameter expanding member 7a, which surface faces one axial side.

[0167] In the reverse input cutoff clutch of this example, when switching between enabling and disabling the reverse input cutoff function, the feed screw shaft 55 can be rotated in both forward and reverse directions using a tool engaged with an engaging portion 60 provided at the radially outer end of the feed screw shaft 55, thereby causing the diameter-expanding member 7a to move back and forth in the radial direction.

[0168] In this example, the engaging portion 60 is configured as an engaging hole such as a hexagonal hole, etc. However, the engaging portion of the feed screw shaft may also be configured as the head of a bolt or the like.

[0169] Other configurations and effects of this example are the same as those of the first example.

[0170] [Example 3] A third example of the embodiment of the present disclosure will be described with reference to FIGS. 11(a) to 12(c).

[0171] In the reverse input cutoff clutch of this example, when switching between enabling and disabling the reverse input cutoff function, the insertion portion 15a of the diameter-expanding member 7b is inserted into the discontinuous portion 43a of the release ring 6a from the radially outer side toward the radially inner side, and is pulled out from the radially inner side toward the radially outer side.

[0172] That is, in this example, the guide portion 13 for the expanding diameter member of the pressed member 2b is positioned so as to overlap radially with the release ring 6a and the circumferential groove 12, and the radially inner end portion opens to the bottom surface of the circumferential groove 12.

[0173] In this example, the insertion portion 15a of the diameter expansion member 7b is provided so as to protrude radially inward from the radially inner end of the column portion 50. In Figures 12(a) to 12(c), a chain line X indicates the boundary between the column portion 50 and the insertion portion 15a.

[0174] In this example, at least a rear portion of the discontinuous portion 43a of the release ring 6a in the insertion direction of the insertion portion 15a relative to the discontinuous portion 43a has a circumferential width that increases toward the rear in the insertion direction. In this example, the insertion portion 15a is inserted into the discontinuous portion 43a from the radially outer side toward the radially inner side, so that the rear side of the insertion direction of the insertion portion 15a relative to the discontinuous portion 43a is the radially outer side.

[0175] Specifically, in this example, the radially inner half of the end faces on both sides of the circumferential direction of the releasing ring 6a is made up of flat surface portions 44a existing in an imaginary plane including the center axis of the releasing ring 6a, and the radially outer half of the end faces on both sides of the circumferential direction of the releasing ring 6a is made up of concave-side inclined surface portions 45a that are inclined in a direction in which the circumferential width of the discontinuous portion 43a increases as they extend radially outward. The concave-side inclined surface portions 45a are made up of flat surfaces.

[0176] In this example, at least a front portion of the insertion portion 15a in the insertion direction of the insertion portion 15a relative to the discontinuous portion 43a has a circumferential width that decreases toward the front in the insertion direction. In this example, the insertion portion 15a is inserted into the discontinuous portion 43a from the radially outer side toward the radially inner side, so that the front side of the insertion portion 15a relative to the discontinuous portion 43a in the insertion direction is the radially inner side.

[0177] Specifically, in this example, the insertion portion 15a has a shape that is a radial inversion of the insertion portion 15 of the first example. That is, the circumferential width of the insertion portion 15a is constant in the rear half (radially outer) in the insertion direction relative to the discontinuous portion 43a, and becomes smaller in the front half (radially inner) in the insertion direction relative to the discontinuous portion 43a toward the front in the insertion direction.

[0178] More specifically, the insertion portion 15a has a pair of convex-side inclined surface portions 46a on both circumferential side surfaces of the front half in the insertion direction, which are inclined toward each other toward the front in the insertion direction. Each of the pair of convex-side inclined surface portions 46a has a front-side convex curved surface portion 47a that forms the front (radially inner) end in the insertion direction, a rear-side convex curved surface portion 48a that forms the rear (radially outer) end in the insertion direction relative to the discontinuous portion 43a, and a concave curved surface portion 49a connecting the front-side convex curved surface portion 47a and the rear-side convex curved surface portion 48a. However, each of the convex-side inclined surface portions 46a may also be formed as a flat surface.

[0179] In this example, when the release ring 6a is in its free state, as shown in Figure 12(a), the shape and dimensions of the pair of concave-side inclined surface portions 45a and the pair of convex-side inclined surface portions 46a are regulated so that the radially inner end of the insertion portion 15a can be inserted between a pair of concave-side inclined surface portions 45a provided on the radially outer half of the end faces on both circumferential sides of the release ring 6a, and the front convex curved surface portions 47a of the pair of convex-side inclined surface portions 46a can be brought into contact with the pair of concave-side inclined surface portions 45a.

[0180] In the normal use state of the reverse input cutoff clutch, the insertion portion 15a is inserted into the discontinuous portion 43a from the radially outer side toward the radially inner side as shown in the order of Figures 12(a) to 12(c) by moving the diameter expansion member 7b from the radially outer side toward the radially inner side, thereby switching the release ring 6a to the first state, whereby the reverse input cutoff function of the reverse input cutoff clutch is switched to active.

[0181] When disabling the reverse input blocking function of the reverse input blocking clutch, the diameter expanding member 7b is moved from the radially inner side to the radially outer side, and the insertion portion 15a is pulled out from the radially inner side to the radially outer side relative to the discontinuous portion 43a, as shown in the order of Figures 12(c) to 12(a), thereby switching the release ring 6a to the second state.

[0182] In addition, when implementing the present disclosure, the diameter expansion member can be configured to be immovable relative to the pressed member. In this case, the diameter expansion member can be configured to be fixed to or integral with the pressed member or the fixed portion. In this case, the release ring can be placed in the first state by inserting the insertion portion of the diameter expansion member into the discontinuous portion and then installing the release ring. From this state, the release ring can be switched to the second state by, for example, pushing the release ring radially inward with a tool inserted into the pressed member from outside the pressed member to release the engagement between the discontinuous portion and the insertion portion. Furthermore, for example, by providing engagement portions such as axial through holes or notches at both circumferential ends of the release ring and engaging the tip of a tool with each of the engagement portions, the insertion portion can be easily inserted and removed from the discontinuous portion using the tool.

[0183] Other configurations and effects of this example are the same as those of the first example.

[0184] [Example 4] A fourth example of the embodiment of the present disclosure will be described with reference to FIG. 13(a) and FIG. 13(b).

[0185] The reverse input cutoff clutch of this example differs from the third example in that it includes a mechanism including a feed screw shaft 55 as a mechanism for moving the diameter expanding member 7c in the radial direction.

[0186] In this example, the mechanism including the feed screw shaft 55 has the same configuration as in Example 2. That is, in this example, the pressed member 2c has a feed screw shaft support hole 57 that penetrates radially in a portion adjacent to one axial side of the diameter expansion member guide portion 13a, and the interior of the diameter expansion member guide portion 13a and the interior of the feed screw shaft support hole 57 communicate with each other via a communication portion 58.

[0187] The radially inner end of the feed screw shaft 55 is rotatably and rattle-free inserted into the feed screw shaft support hole 57. The radially outer end of the feed screw shaft 55 is located radially outward of the column portion 50a of the diameter expansion member 7c, and is supported by a support member such as a bearing so as to be only rotatable relative to a fixed portion such as a housing that supports and fixes the pressed member 2c.

[0188] The diameter expanding member 7c has rack teeth 59 that mesh with the feed screw portion 56 and convert the rotation of the feed screw shaft 55 into linear movement in the radial direction of the member itself. In this example, the rack teeth 59 are provided on the outer peripheral surfaces of the column portion 50a and the insertion portion 15a of the diameter expanding member 7c, facing one axial side.

[0189] Other configurations and effects of this example are the same as those of the third example.

[0190] [Example 5] A fifth example of the embodiment of the present disclosure will be described with reference to FIG. 14(a) and FIG. 14(b).

[0191] The reverse input cutoff clutch of this example differs from the third example in the structure of the diameter expansion member 7d and the mechanism for moving the diameter expansion member 7d in the radial direction.

[0192] In this example, the diameter-expanding member 7d is configured as a screw member that is screwed into the pressed member 2d in the radial direction and has an insertion portion 15b at its radially inner end.

[0193] Specifically, in this example, the guide portion 13b for the diameter-expanding member of the pressed member 2d is configured by a screw hole.

[0194] The diameter expanding member 7d is made up of a screw shaft that is screwed into the diameter expanding member guide portion 13b, and has an insertion portion 15b at its radially inner end.

[0195] In this example, at least the front (radially inner) portion of the insertion portion 15b in the insertion direction relative to the discontinuous portion 43a has a circumferential width that decreases toward the front in the insertion direction.

[0196] Specifically, in this example, the front half in the insertion direction (radially inner half) is configured by a conical surface portion 61 whose outer diameter becomes smaller toward the front in the insertion direction.

[0197] In the reverse input cutoff clutch of this example, when switching between enabling and disabling the reverse input cutoff function, the diameter expanding member 7d can be moved back and forth in the radial direction by rotating the diameter expanding member 7d in both forward and reverse directions using a tool engaged with the engaging portion 60a provided at the radially outer end of the diameter expanding member 7d.

[0198] In the illustrated example, the engaging portion 60a is configured by the head of a bolt. However, the engaging portion of the diameter expanding member may also be configured by an engaging hole such as a hexagonal hole.

[0199] Other configurations and effects of this example are the same as those of the third example.

[0200] The first to fifth examples of the embodiment of the present disclosure can be implemented in any suitable combination as long as no contradiction occurs. [Explanation of symbols]

[0201] 1 Reverse input cutoff clutch 2, 2a, 2b, 2c, 2d Pressurized member 3 Input member 4 Output member 5 Engagement element 6, 6a Release ring 7, 7a, 7b, 7c Diameter expansion member 8 Pressed surface 9 Large diameter cylindrical surface 10 Small diameter cylindrical surface part 11 Connection surface 12 Circumferential groove 13, 13a, 13b Guide portion for expanding member 14 Cutout 15, 15a, 15b Insertion part 16 Inward flange 17 screw holes 18 Input side engagement portion 19 Radial inner surface 20 Input shaft 21 Radial outer surface 22 Output side engagement portion 23 Flat surface 24 Convex curved surface 25 Output shaft 26 Small diameter shaft 27 Output flange 28 Radial Rolling Bearing 29 Outer ring 30 Inner Circle 31 Rolling elements 32a, 32b retaining ring 33 Plain bearings 34 Pressing surface 35 Input side engaged portion 36 Output side engaged part 37 Release engagement portion 38 Engagement body 39 Protrusion 40 Radial inner surface 41 Flat surface part 42 Convex part 43, 43a Discontinuity 44, 44a Flat surface part 45, 45a Concave inclined surface part 46, 46a Convex inclined surface part 47, 47a Front convex curved part 48, 48a Rear convex curved part 49, 49a Concave curved part 50, 50a pillar section 51 biasing member 52 spacer 53 Stopper member 54 Through hole 55 feed screw shaft 56 Feed screw section 57 Feed screw shaft support hole 58 Communication part 59 rack teeth 60, 60a Engagement portion 61 Conical surface 62 Inner surface 63 Engagement surface

Claims

1. a pressed member having a pressed surface on its inner circumferential surface; an input member having an input-side engaging portion disposed radially inside the pressed surface and disposed coaxially with the pressed surface; an output member having an output side engaging portion disposed radially inward of the input side engaging portion and disposed coaxially with the pressed surface; an engaging element having a pressing surface facing the pressed surface, an input side engaged portion engageable with the input side engaging portion, and an output side engaged portion engageable with the output side engaging portion, the engaging element being arranged to be movable in a radial direction; a release ring configured in a segmented annular shape having a discontinuous portion on its inner circumferential surface and at one location in the circumferential direction; an expanding member having an insertion portion that is inserted into the discontinuous portion, The engagement element has a release engagement portion disposed radially inside the release ring, The release ring is switchable between a first state in which the insertion portion is inserted into the discontinuous portion, elastically expanding the circumferential width of the discontinuous portion, thereby expanding the diameter thereof, and the release engagement portion does not contact the inner peripheral surface of the release ring even when the pressing surface is pressed against the pressed surface; and a second state in which the engagement between the discontinuous portion and the insertion portion is released, and the release ring is contracted in diameter by elastically restoring itself, and the pressing surface is prevented from being pressed against the pressed surface based on the engagement between the inner peripheral surface of the release ring and the release engagement portion. When the release ring is switched to the first state, when a rotational torque is input to the input member, the input side engaging portion engages with the input side engaged portion, and the engaging element moves away from the pressed surface, causing the output side engaged portion to engage with the output side engaging portion, thereby transmitting the rotational torque input to the input member to the output member, whereas when a rotational torque is input in reverse to the output member, the output side engaging portion engages with the output side engaged portion, and the pressing surface is pressed against the pressed surface, causing the pressing surface to frictionally engage with the pressed surface, When the release ring is switched to the second state, the engagement element transmits torque between the input member and the output member regardless of the direction of torque transmission between the input member and the output member. Reverse input cut-off clutch.

2. 2. The reverse input cutoff clutch according to claim 1, wherein the diameter expanding member is configured to be movable relative to the pressed member, and the insertion portion can be inserted into and removed from the discontinuous portion based on the movement.

3. The reverse input cutoff clutch according to claim 2 , wherein the insertion portion is inserted into the discontinuous portion from a radially inner side toward a radially outer side, and is removed from the radially outer side toward a radially inner side.

4. The reverse input cutoff clutch according to claim 2 , wherein the insertion portion is inserted into the discontinuous portion from the radially outer side toward the radially inner side, and is removed from the radially inner side toward the radially outer side.

5. 5. The reverse input cutoff clutch according to claim 4, wherein the diameter expanding member is configured as a screw member that is screwed radially onto the pressed member and has the insertion portion at an end on the radially inner side.

6. a feed screw shaft having a feed screw portion on an outer peripheral surface and supported by the pressed member so as to be rotatable only; the expanding member has rack teeth that engage with the feed screw portion, and is supported so as to be movable relative to the pressed member in association with rotation of the feed screw shaft; 3. The reverse input disconnecting clutch according to claim 2.

7. 3. The reverse input cutoff clutch according to claim 1, wherein at least a rear portion of the discontinuous portion in the insertion direction of the insertion portion relative to the discontinuous portion has a circumferential width that increases toward the rear side in the insertion direction.

8. 3. The reverse input cutoff clutch according to claim 1, wherein at least a front portion of the insertion portion in the insertion direction relative to the discontinuous portion has a circumferential width that decreases toward the front in the insertion direction.

9. 3. The reverse input cutoff clutch according to claim 1, wherein the pressed member has a circumferential groove in a portion of its inner peripheral surface that is axially offset from the pressed surface, into which the release ring enters when the release ring is switched to the first state.

10. 3. The reverse input cut-off clutch according to claim 1, wherein the engaging element includes an engaging element main body having the pressing surface, the input side engaged portion, and the output side engaged portion, and the release engaging portion is configured to protrude in the axial direction from the engaging element main body.

11. The reverse input cut-off clutch according to claim 10, wherein the release engagement portion has a protrusion that protrudes radially outward at a portion that is axially farther from the engagement element body than a portion that engages with the inner peripheral surface of the release ring.

12. 3. The reverse input cutoff clutch according to claim 1, wherein the engagement element is made up of a plurality of engagement elements arranged at different positions in the circumferential direction.

Images