Reverse-input cutoff clutch

Abstract

Provided is a structure of a reverse-input cutoff clutch that, irrespective of usage conditions and the like, suppresses the phenomenon of a pressing surface slipping against a pressed surface, thus enabling an output member to be reliably locked or semi-locked. An engagement element 5 has a recessed groove 52 crossing a pressing surface 34 that is frictionally engaged with a pressed surface 6 when rotational torque is reversely inputted to an output member 4.

Description

Reverse input blocking clutch

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

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

[0003] The reverse input blocking clutch is roughly classified into a lock-type reverse input blocking clutch provided with a mechanism for preventing the rotation of the output member when a rotational torque is reversely input to the output member, and a free-type reverse input blocking clutch provided with a mechanism for idling the output member when a rotational torque is input to the output member, depending on the difference in the mechanism for blocking the rotational torque reversely input to the output member. Which of the lock-type reverse input blocking clutch and the free-type reverse input blocking clutch to be used is appropriately determined depending on the application of the device incorporating the reverse input blocking clutch and the like.

[0004] In the lock-type reverse input blocking clutch described in International Publication No. 2019 / 0,26794, when a rotational torque is input to the input member, based on the engagement of the input-side engaging portion of the input member with the input-side engaged portion of the engaging element, the engaging element moves in a direction away from the pressed surface provided on the pressed member, and the output-side engaged portion of the engaging element is engaged with the output-side engaging portion of the output member, thereby transmitting the rotational torque input to the input member to the output member. On the other hand, when a rotational torque is reversely input to the output member, based on the engagement of the output-side engaging portion with the output-side engaged portion, the pressing surface is pressed against the pressed surface, and the pressing surface is frictionally engaged with the pressed surface.

[0005] International Publication No. 2019 / 026794

[0006] In the reverse input blocking clutch described in International Publication No. 2019 / 026794, a lubricant such as grease is applied between the pressed surface of the pressed member and the pressing surface of the engaging element to prevent wear at the contact point between the pressed surface and the pressing surface of the engaging element.

[0007] However, it has been found that, depending on the operating conditions of the reverse input blocking clutch, if the pressing surface slips against the pressed surface while the pressing surface is frictionally engaged with the pressed surface, and rotational torque is reversed into the output member, it may become impossible to reliably lock or partially lock the output member.

[0008] The present disclosure aims to realize a reverse input blocking clutch structure that can reliably lock or partially lock an output member by suppressing the phenomenon of the pressing surface slipping against the pressed surface, regardless of the usage conditions.

[0009] A reverse input blocking clutch according to one aspect of the present disclosure comprises a pressed member, an input member, an output member, and an engaging element.

[0010] The member to be pressed has a surface to be pressed on its inner circumferential surface.

[0011] The input member has an input-side engaging portion located radially inward of the pressed surface and is arranged coaxially with the pressed surface.

[0012] The output member has an output-side engaging portion that is located radially inward from the input-side engaging portion and is arranged coaxially with the pressed surface.

[0013] The engaging element has a pressing surface facing the pressed surface, an input-side engaged portion that can engage with the input-side engaging portion, and an output-side engaged portion that can engage with the output-side engaging portion, and is arranged to be movable in the radial direction.

[0014] When rotational torque is input to the input member, the engaging element moves radially away from the pressed surface based on the input-side engaging portion engaging with the input-side engaged portion, thereby engaging the output-side engaged portion with the output-side engaging portion and transmitting the rotational torque input to the input member to the output member. Conversely, when rotational torque is input in reverse to the output member, the engaging element presses the pressing surface against the pressed surface based on the output-side engaging portion engaging with the output-side engaged portion, causing the pressing surface to frictionally engage with the pressed surface.

[0015] In particular, in a reverse input blocking clutch according to one aspect of the present disclosure, the engaging element has a groove that crosses the pressing surface.

[0016] In a reverse input blocking clutch according to one aspect of the present disclosure, the groove extends in the circumferential direction.

[0017] In a reverse input shutoff clutch according to one aspect of the present disclosure, the pressing surface is composed of two pressing surfaces provided at two positions spaced apart from each other in the circumferential direction, and each of the two pressing surfaces may be provided with the groove. In this case, the grooves provided on each of the two pressing surfaces may be configured not to be continuous with each other.

[0018] According to one aspect of the reverse input blocking clutch of this disclosure, regardless of the operating conditions, the phenomenon of the pressing surface slipping against the pressed surface can be suppressed, and the output member can be reliably locked or partially locked.

[0019] Figure 1 is a cross-sectional view of a reverse input shut-off clutch according to a first embodiment of the present disclosure. Figure 2 is a cross-sectional view taken along line I-I of Figure 1. Figure 3 is a cross-sectional view taken along line I-I of Figure 1, showing the state in which rotational torque is input to the input member, with the holding member and biasing member omitted. Figure 4 is a cross-sectional view taken along line I-I of Figure 1, showing the state in which rotational torque is input in reverse to the output member, with the holding member and biasing member omitted. Figure 5 is a perspective view showing the engaging element of the first example of the reverse input shut-off clutch removed. Figure 6A is a front view of the engaging element of the first example of the reverse input shut-off clutch. Figure 6B is a plan view taken from above Figure 6A. Figure 6C is a side view taken from the right side of Figure 6A. Figure 7A schematically shows an example of a groove provided in the engaging element. Figure 7B schematically shows an example of a groove provided in the engaging element. Figure 7C schematically shows an example of a groove provided in the engaging element. Figure 7D schematically shows an example of a groove provided in the engaging element. Figure 8 is a perspective view showing the engaging element of a second example reverse input shut-off clutch according to an embodiment of the present disclosure. Figure 9A is a front view of the engaging element of the second example reverse input shut-off clutch. Figure 9B is a top view of Figure 9A. Figure 9C is a side view of Figure 9A from the right. Figure 10A is a front view of the engaging element of a third example reverse input shut-off clutch according to an embodiment of the present disclosure. Figure 10B is a top view of Figure 10A. Figure 10C is a side view of Figure 10A from the right. Figure 11A is a front view of the engaging element of a fourth example reverse input shut-off clutch according to an embodiment of the present disclosure. Figure 11B is a side view of Figure 11A from the right.

[0020] [First Example] A first example of an embodiment of the present disclosure will be described with reference to Figures 1 to 6C.

[0021] In the following description, unless otherwise specified, the axial, radial, and circumferential directions refer to the axial, radial, and circumferential directions of the pressed surface 6. The axial, radial, and circumferential directions of the pressed surface 6 coincide with the axial, radial, and circumferential directions of the input member 3, and also coincide with the axial, radial, and circumferential directions of the output member 4. Furthermore, one axial side refers to the input member 3 side (right side in Figure 1), and the other axial side refers to the output member 4 side (left side in Figure 1).

[0022] The axial direction of the engaging element 5 coincides with the axial direction of the pressed surface 6. The circumferential direction of the pressing surface 34 of the engaging element 5 coincides with the circumferential direction of the pressed surface 6. The direction of the pressing surface 34 of the engaging element 5 relative to the pressed surface 6 is defined as the first direction (up and down direction in Figures 2 to 4), and the direction perpendicular to both the axial direction of the pressed surface 6 and the first direction is defined as the second direction (left and right direction in Figures 2 to 4). For the engaging element 5, the direction coinciding with the first direction is defined as its radial direction (direction indicated by arrow α in Figure 3), and the direction coinciding with the second direction is defined as its width direction (direction indicated by arrow β in Figure 3).

[0023] <Explanation of the structure of the reverse input blocking clutch> The reverse input blocking clutch 1 comprises a pressed member 2, an input member 3, an output member 4, and an engaging element 5. The reverse input blocking clutch 1 transmits the rotational torque input to the input member 3 to the output member 4, while the rotational torque that is reverse input to the output member 4 is either completely blocked and not transmitted to the input member 3, or only a portion of it is transmitted to the input member 3 and the rest is blocked, thus having a reverse input blocking function.

[0024] (Pressed member) The pressed member 2 has a pressed surface 6 on its inner circumferential surface.

[0025] The pressed member 2 is supported and fixed to a stationary part that does not rotate even when the reverse input blocking clutch 1 is in use, or it is integrally provided with the stationary part so that its rotation is restrained.

[0026] The pressed surface 6 constitutes the surface that contacts the pressing surface 34 of the engaging element 5 when the engaging element 5 moves radially outward, which is the direction towards the pressed surface 6. The shape of the pressed member 2 is not limited as long as it is configured to have the pressed surface 6 on its inner circumferential surface. The pressed surface 6 is annular when viewed from the axial direction, but is not limited to this, although in this example it has a cylindrical shape in which the inner diameter does not change with respect to the axial direction.

[0027] The input-side engaging portion 13 of the input member 3 and the output-side engaging portion 21 of the output member 4 are positioned radially inward of the pressed surface 6. The input-side engaging portion 13, the output-side engaging portion 21, and the engaging element 5 are rotatable radially inward of the pressed surface 6.

[0028] As in this example, the pressed member 2 may include a housing element 7.

[0029] The housing element 7 has a stepped cylindrical inner surface. Specifically, the inner surface of the housing element 7 is formed by connecting a large-diameter cylindrical surface portion 8 on one axial side and a small-diameter cylindrical surface portion 9 on the other axial side with a connecting surface portion 10 facing one axial side. The pressed surface 6 is formed by the large-diameter cylindrical surface portion 8.

[0030] The housing element 7 has an inwardly projecting flange portion 11 at the other axial end of the small-diameter cylindrical surface portion 9, and has screw holes 12 opening at multiple locations in the circumferential direction on the other axial side surface. The pressed member 2 is supported and fixed to the stationary portion by screwing a bolt, which is inserted through a through hole provided in the stationary portion, into the screw holes 12.

[0031] In this case, the pressed member 2 may also include another housing element that closes the opening on one axial side of the housing element 7. The other housing element is fitted (spigot fitting) to the axial end of the housing element 7 without any play and is radially positioned, and is connected to the housing element 7 by a connecting member such as a bolt.

[0032] (Input Member) The input member 3 has an input-side engaging portion 13 located radially inward of the pressed surface 6 and is arranged coaxially with the pressed surface 6. The input member 3 can be rotatably supported by the pressed member 2 or the stationary portion.

[0033] The input member 3 is connected to an input-side mechanism such as an electric motor, and rotational torque is input to it. Specifically, the input member 3 is composed of the output shaft of the input-side mechanism, or it is composed as a separate component from the output shaft and can be fixed coaxially to the output shaft.

[0034] The input-side engaging portion 13 is provided so as to extend axially from a portion of the input member 3 that is radially outward from the center of rotation, and has a portion that engages with the input-side engaged portion 35 of the engaging element 5. Specifically, a part of the radially inner surface 15 of the input-side engaging portion 13 comes into contact with the radially inner surface 39 of the input-side engaged portion 35 as the input member 3 or engaging element 5 rotates, and engages with the radially inner surface 39 by pressing it radially inward.

[0035] The outer circumferential surface of the input-side engaging portion 13 can adopt any configuration as long as it has a portion that engages with the input-side engaged portion 35. For example, it can have an end face shape such as a substantially fan-shaped, substantially trapezoidal, or arched shape, where the circumferential width increases towards the radially outward direction when viewed from the axial direction. From the standpoint of reducing the manufacturing cost of the input member 3, it is preferable that the outer circumferential surface of the input-side engaging portion 13, as in this example, is composed only of a flat radially inward surface 15 and a partially cylindrical radially outward surface 17 centered on the central axis of the input member 3, and has an arched end face shape.

[0036] In this example, the radially inner surface 15 and the radially outer surface 17 are connected by a pointed edge 19. Therefore, when manufacturing the input member 3, it is not necessary to perform machining on the connection between the radially inner surface 15 and the radially outer surface 17 of the input-side engaging portion 13. For example, the input member 3 can be manufactured by forging a metal material to form its outer shape, and then performing finishing processes such as grinding as needed. However, the input member 3 can also be manufactured by machining a metal material, including cutting. In this case, the radially inner surface 15 and the radially outer surface 17 can also be connected by chamfered portions such as corner chamfers and rounded chamfers.

[0037] As in this example, the input member 3 may have, in addition to the input-side engaging portion 13, an input shaft portion 14 and an input flange portion 20.

[0038] The input shaft portion 14 has a cylindrical shape. One axial side of the input shaft portion 14 is connected to the output shaft or the like. In this example, the input shaft portion 14 is rotatably supported inside the stationary portion by a radial bearing (not shown).

[0039] The input flange portion 20 projects radially outward over the entire circumference from the outer peripheral surface of the end portion on the other axial side of the input shaft portion 14.

[0040] In this example, the input side engaging portion 13 projects toward the other axial side from a portion of the side surface on the other axial side of the input flange portion 20 that is radially outside from the rotation center.

[0041] The number of the input side engaging portions 13 is determined according to the number of the engaging elements 5. When the engaging element 5 is composed of a plurality of engaging elements 5, the input side engaging portion 13 is also composed of a plurality of input side engaging portions 13. In this example, since the engaging element 5 is composed of two engaging elements 5, the input side engaging portion 13 is also composed of two input side engaging portions 13. The two input side engaging portions 13 are arranged at two positions on the radially opposite sides of the side surface on the other axial side of the input flange portion 20 and are spaced apart from each other in the radial direction of the input member 3.

[0042] (Output member) The output member 4 has an output side engaging portion 21 arranged radially inside the input side engaging portion 13 and is arranged coaxially with the pressed surface 6 and the input member 3. The output member 4 can be rotatably supported by the pressed member 2 or the stationary portion.

[0043] The output member 4 is connected to an output side mechanism such as a speed reduction mechanism and is configured to output rotational torque to the output side mechanism as it rotates. Specifically, the output member 4 is composed of an input shaft of the output side mechanism or the like, or is configured as a separate member from the input shaft or the like and can be fixed coaxially to the input shaft or the like.

[0044] The output side engaging portion 21 has a portion that engages with the output side engaged portion 36 of the engaging element 5, and the engaging portion is radially inside the input side engaging portion 13 and is a portion that is radially outside from the central axis 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. A part of the outer peripheral surface of the output side engaging portion 21 engages with the output side engaged portion 36 as the output member 4 or the engaging element 5 rotates.

[0045] The output-side engaging portion 21 has a cam function. The distance from the rotation center axis of the output member 4 to the outer peripheral surface of the output-side engaging portion 21, which is the portion that engages with the output-side engaged portion 36, is not constant in the circumferential direction. Thus, when a rotational torque is reversely input to the output member 4, as the output member 4 rotates, the portion of the outer peripheral surface of the output-side engaging portion 21 that is far from the rotation center axis of the output member 4 comes into contact with the output-side engaged portion 36 of the engaging element 5 and engages with the output-side engaged portion 36 so as to press it radially outward, enabling the output-side engaging portion 21 to press the engaging element 5 radially outward.

[0046] On the other hand, when a rotational torque is input to the input member 3, the engaging element 5 moves radially inward, and the output-side engaged portion 36 of the engaging element 5 first comes into contact with the portion of the outer peripheral surface of the output-side engaging portion 21 that is far from the rotation center axis of the output member 4. Further, the output member 4 rotates so that the output-side engaged portion 36 and the output-side engaging portion 21 are parallel, and the portion of the outer peripheral surface of the output-side engaging portion 21 that can come into contact with the output-side engaged portion 36 engages smoothly regardless of the distance from the rotation center axis of the output member 4.

[0047] The number of portions of the output-side engaging portion 21 that engage with the output-side engaged portion 36 is determined according to the number of engaging elements 5. When the engaging element 5 is constituted by a plurality of engaging elements 5, the output-side engaging portion 21 is also configured to have a plurality of engaging portions. In this example, the output-side engaging portion 21 has portions that engage with two output-side engaged portions 36 in accordance with the number of engaging elements 5. However, even when the number of engaging elements 5 is one, it is possible to adopt the same structure as this example.

[0048] The outer circumferential surface of the output-side engaging portion 21 can adopt any configuration as long as the output-side engaging portion 21 has a cam function, and its shape is appropriately set according to the number of portions of the output-side engaging portion 21 that engage with the output-side engaged portion 36. When there are portions that engage with two output-side engaged portions 36, the output-side engaging portion 21 can be, for example, roughly rectangular, roughly oval, parallelogram, or trapezoidal in shape. However, from the standpoint of reducing the manufacturing cost of the output member 4, it is preferable that the outer circumferential surface of the output-side engaging portion 21 has a flat surface portion 22 in the portion that engages with the output-side engaged portion 36, and it is even more preferable that it is composed of a flat surface portion 22 and a partially cylindrical surface portion 23 centered on the central axis of the output member 4.

[0049] In this example, the outer circumferential surface of the output-side engaging portion 21 is composed of two parallel flat surface portions 22 and two partially cylindrical surface portions 23. Of each flat surface portion 22, the portion located in the axial middle and widthwise middle constitutes the portion that engages with the output-side engaged portion 36. The output-side engaging portion 21 is symmetrical with respect to a virtual plane that passes through the rotational axis of the output member 4 and is perpendicular to the two flat surface portions 22. Furthermore, the output-side engaging portion 21 is symmetrical with respect to a virtual plane that passes through the rotational axis of the output member 4 and is parallel to the two flat surface portions 22. In other words, the output-side engaging portion 21 has a shape that is twice symmetrical with respect to the central axis of the output member 4. The flat surface portions 22 and the partially cylindrical surface portions 23 are connected by a pointed edge portion 24.

[0050] Therefore, when manufacturing the output member 4 having the output-side engaging portion 21, it is not necessary to perform machining on the portion of the output-side engaging portion 21 that engages with the output-side engaged portion 36. For example, the output member 4 can be manufactured by forging a metal material to form its outer shape, and then performing finishing processes such as grinding as needed. However, the output member 4 can also be manufactured by machining a metal material, including cutting. In this case, the flat surface portion 22 and the partially cylindrical surface portion 23 can be connected by chamfered portions such as corner chamfers and rounded chamfers.

[0051] As in this example, when the engaging element 5 is composed of two engaging elements 5, the output-side engaging portion 21 is located radially inward of the two input-side engaging portions 13 and is positioned between the output-side engaged portions 36 of the two engaging elements 5.

[0052] As in this example, the output member 4 may have, in addition to the output-side engaging portion 21, an output shaft portion 25, an output flange portion 26, and a small-diameter shaft portion 27.

[0053] The output shaft portion 25 has a stepped cylindrical shape. The output shaft portion 25 is connected to the input shaft of the output mechanism, etc.

[0054] The output flange portion 26 protrudes radially outward from the outer circumferential surface of one axial end of the output shaft portion 25 along its entire circumference.

[0055] In this example, the output-side engaging portion 21 protrudes from the center of the end face on one axial side of the output shaft portion 25 toward the axial side.

[0056] The small-diameter shaft portion 27 has a cylindrical shape and protrudes from the center of the end face on one axial side of the output-side engaging portion 21 toward the one axial side.

[0057] In this example, the output shaft portion 25 is rotatably supported radially inward of the housing element 7 of the pressed member 2 by a radial rolling bearing 28. The outer ring 29 of the radial rolling bearing 28 is fitted snugly into the small-diameter cylindrical surface portion 9 of the housing element 7 and is axially clamped between one axial side surface of the inward flange portion 11 and a retaining ring 30a that is locked to one axial end of the small-diameter cylindrical surface portion 9. The inner ring 31 of the radial rolling bearing 28 is fitted snugly onto one axial end of the output shaft portion 25 and is axially clamped between the other axial side surface of the output flange portion 26 and a retaining ring 30b that is locked to the outer circumferential surface of the axial intermediate portion of the output shaft portion 25.

[0058] The radial rolling bearing 28 can be constructed using ball bearings, tapered roller bearings, or cylindrical roller bearings as rolling elements 32.

[0059] The small-diameter shaft portion 27 of the output member 4 is supported by a sliding bearing (sleeve) 33 inside the input member 3, allowing for free rotation relative to the input member 3.

[0060] (Engaging element) The engaging element 5 has a pressing surface 34 facing the pressed surface 6, an input-side engaged portion 35 that can engage with the input-side engaging portion 13, and an output-side engaged portion 36 that can engage with the output-side engaging portion 21, and is arranged to allow movement of the engaging element 5 in the radial direction (first direction).

[0061] When rotational torque is input to the input member 3, the engaging element 5 moves radially away from the pressed surface 6 based on the input-side engaging portion 13 engaging with the input-side engaged portion 35, and transmits the rotational torque input to the input member 3 to the output member 4 by engaging the output-side engaged portion 36 with the output-side engaging portion 21. Conversely, when rotational torque is input in reverse to the output member 4, the pressing surface 34 is pressed against the pressed surface 6 based on the output-side engaging portion 21 engaging with the output-side engaged portion 36, causing the pressing surface 34 to frictionally engage with the pressed surface 6.

[0062] The pressing surface 34 is provided on at least a portion of the radially outer surface of the engaging element 5 facing the pressed surface 6. The pressing surface 34 can be composed of one pressing surface 34 which is made up of the whole or a portion of the radially outer surface of the engaging element 5. Alternatively, as in this example, the pressing surface 34 can be composed of two pressing surfaces 34 provided at two positions on the radially outer surface of the engaging element 5 that are spaced apart from each other in the circumferential direction. The pressing surface 34 can have a radius of curvature that is less than or equal to the radius of curvature of the pressed surface 6. In this example, each pressing surface 34 is composed of a partially cylindrical convex curved surface having a radius of curvature smaller than the radius of curvature of the pressed surface 6.

[0063] In a structure having two pressing surfaces 34, as in this example, the portion of the radially outer surface of the engaging element 5 that is circumferentially separated from the two pressing surfaces 34 is located radially inward from a virtual circle that is centered on the central axis of the input member 3 and tangent to the two pressing surfaces 34, when viewed from the axial direction. That is, when the two pressing surfaces 34 are in contact with the surface to be pressed 6, the portion that is circumferentially separated from the two pressing surfaces 34 does not come into contact with the surface to be pressed 6.

[0064] The input-side engaged portion 35 has a portion that engages with the input-side engaged portion 13 of the input member 3. The input-side engaged portion 35 has a shape and size that allows the input-side engaged portion 13 to be loosely inserted. The input-side engaged portion 35 can be formed by a through hole that penetrates the engaging element 5 axially, located in the radially intermediate portion of the widthwise center of the engaging element 5, a recess that opens on the other axial side of the engaging element 5, or a recess that opens on the radially outer surface of the engaging element 5. More specifically, a part of the radially inner surface 39 of the input-side engaged portion 35 contacts and engages with the radially inner surface 15 of the input-side engaged portion 13 as the input member 3 or the engaging element 5 rotates.

[0065] In this example, the input-side engaged portion 35 is provided in the radially intermediate portion of the widthwise center of the engaging element 5. More specifically, although not limited to this, the input-side engaged portion 35 has a substantially arc-shaped opening when viewed from the axial direction and is composed of a through hole that penetrates the radially intermediate portion of the widthwise center of the engaging element 5 in the axial direction.

[0066] With the input-side engaging portion 13 inserted inside the input-side engaged portion 35, gaps exist between the input-side engaging portion 13 and the inner surface of the input-side engaged portion 35 in the width direction and the radial direction of the engaging element 5. Therefore, the input-side engaging portion 13 can be displaced relative to the input-side engaged portion 35 in the rotational direction of the input member 3, and the input-side engaged portion 35 can be displaced radially relative to the input-side engaging portion 13.

[0067] In the reverse input blocking clutch 1 of this example, the engaging element 5 has a groove 52 that crosses the pressing surface 34. The groove 52 crossing the pressing surface 34 means, for example, that it extends in any direction across the entire pressing surface 34, which is the portion of the radial outer surface of the engaging element 5 that comes into contact with the pressed surface 6, as shown by the oblique grid in Figures 7A to 7D.

[0068] The contact area between the pressed surface 6 of the pressed member 2 and the pressing surface 34 of the engaging element 5 is lubricated with a lubricant such as grease to prevent wear at these contact points. If the amount of lubricant interposed between the pressed surface 6 and the pressing surface 34 becomes excessive, depending on the operating conditions of the reverse input blocking clutch 1, the pressing surface 34 may slip against the pressed surface 6 while frictionally engaged with it. If such slippage of the pressing surface 34 against the pressed surface 6 occurs, it may become impossible to reliably lock or partially lock the output member 4 when rotational torque is reversed into the output member 4. This phenomenon is particularly likely to occur in low-temperature environments, such as below 0°C, where the viscosity of the lubricant increases and the traction coefficient decreases.

[0069] In the reverse input blocking clutch 1 of this example, if an excessive amount of lubricant is attached to the pressing surface 34 or the pressed surface 6, the engaging element 5 moves radially outward due to the rotation of the output member 4 or the restoring force of the biasing member 43, causing some of the lubricant attached to the pressing surface 34 or the pressed surface 6 to enter the groove 52, move along the groove 52, and be released to the portion away from the contact area between the pressing surface 34 and the pressed surface 6. This allows for proper adjustment of the amount of lubricant interposed between the pressing surface 34 and the pressed surface 6. Therefore, while the pressing surface 34 is frictionally engaged with the pressed surface 6, the pressing surface 34 is reliably prevented from slipping against the pressed surface 6, and the output member 4 can be reliably locked or semi-locked.

[0070] The number of grooves 52 formed on the pressing surface 34 is not particularly limited. The grooves 52 may consist of one groove 52 or two or more grooves 52.

[0071] The direction of extension (formation direction) of the groove 52 is not particularly limited, as long as the amount of lubricant interposed between the pressed surface 6 and the pressing surface 34 can be appropriately adjusted. For example, as shown in Figure 7A, the groove 52 can extend circumferentially on the pressing surface 34. In this case, the groove 52 can also extend further circumferentially beyond the pressing surface 34 to the radial outer surface of the engaging element 5. Alternatively, as shown in Figure 7B, the groove 52 can extend axially on the pressing surface 34. Alternatively, as shown in Figure 7C, the groove 52 can extend in a direction inclined in either the circumferential or axial direction on the pressing surface 34. Furthermore, as shown in Figure 7D, the groove 52 can extend in multiple different directions.

[0072] The depth and width dimensions of the groove 52 are not particularly limited, as long as sufficient frictional force can be secured between the pressed surface 6 and the pressing surface 34, and the amount of lubricant interposed between the pressed surface 6 and the pressing surface 34 can be appropriately adjusted.

[0073] The depth of the groove 52 is not limited to this, but can be 5% to 20% of the axial thickness of the engaging element 5, preferably 10% to 15%. The width of the groove 52 is not limited to this, but can be 20% to 55% of the axial thickness of the engaging element 5, preferably 25% to 50%. If the groove 52 is composed of multiple grooves 52, the sum of the widths of the multiple grooves 52 can be 20% to 55% of the axial thickness of the engaging element 5.

[0074] The cross-sectional shape of the groove 52 is not particularly limited and can be any shape. For example, the cross-sectional shape of the groove 52 can be a rectangle, triangle, semicircle, U-shape, or a similar shape.

[0075] The groove 52 can be formed by machining or other processes after the engaging element 5 has been manufactured by pressing, sintering, forging, casting, cutting, or any combination thereof.

[0076] The pressing surface 34 is composed of two pressing surfaces 34 located at two positions spaced apart from each other in the circumferential direction, and each of the two pressing surfaces 34 is provided with a groove 52, that is, the groove 52 crosses each of the two pressing surfaces 34 in the circumferential direction. In such cases, the groove 52 can be formed to extend along the radial outer surface of the engaging element 5 so that the grooves 52 on each of the two pressing surfaces 34 are continuous with each other, or, as in this example, the two grooves 52 can not be continuous with each other, that is, the grooves 52 on each of the two pressing surfaces 34 can be formed independently of each other. When the groove 52 crosses the pressing surface in the circumferential direction, the groove 52 is formed by cutting. However, when the grooves 52 on each of the two pressing surfaces 34 are configured not to be continuous with each other, the amount of chips generated when forming the groove 52 by cutting can be reduced compared to when they are configured to be continuous with each other.

[0077] In this example, each of the two pressing surfaces 34 is provided with one groove 52 extending in the circumferential direction. The grooves 52 on each of the two pressing surfaces 34 are not continuous with each other. Each groove 52 has a rectangular cross-sectional shape.

[0078] The ends of the groove 52 on both sides in the circumferential direction are positioned circumferentially away from the pressing surface 34. That is, one end of the groove 52 in the circumferential direction is located one side further circumferentially than one end of the pressing surface 34 in the circumferential direction, and the other end of the groove 52 in the circumferential direction is located the other side further circumferentially than the other end of the pressing surface 34 in the circumferential direction. As a result, as the engaging element 5 moves radially outward, some of the excess lubricant adhering to the pressing surface 34 or the pressed surface 6 can be reliably drawn into the groove 52 and released along the groove 52 to a portion circumferentially away from the contact point between the pressed surface 6 and the pressing surface 34.

[0079] The lubricant that has escaped in the circumferential direction from the contact area between the pressed surface 6 and the pressing surface 34 is spread out by the radially outer surface of the engaging element 5 as the engaging element 5 rotates due to the input torque applied to the input member 3, and is reapplied to the pressed surface 6.

[0080] Furthermore, the lubricant that lubricates the space between the pressed surface 6 and the pressing surface 34 is applied to the entire circumference of the pressed surface 6, for example, at the time of factory shipment. Additionally, the space between the input-side engaging portion 13 and the input-side engaged portion 35, or between the output-side engaging portion 21 and the output-side engaged portion 36, can also be lubricated with the lubricant.

[0081] The type of lubricant is not particularly limited as long as it can lubricate the space between the pressed surface 6 and the pressing surface 34. For example, a lubricant with relatively high viscosity (a kinematic viscosity of the base oil at 40°C of 45 mmHg) is suitable. ２ / s or more 170mm ２ Grease (less than / s) can be used as a lubricant. However, as a lubricant, a traction oil or other lubricant with relatively low viscosity (kinematic viscosity of the base oil at 40°C of 15 mm²) can be used. ２ / s or more 35mm ２ You can also use things that are less than or equal to / s.

[0082] The engaging element 5 can be composed of one engaging element 5 or two or more engaging elements 5, as long as it has the above configuration. In this example, the engaging element 5 is composed of two engaging elements 5. Each engaging element 5 has the function of an engaging element 5.

[0083] The engaging element 5 can be composed of a single component, as in this example, meaning the whole can be constructed as a single unit, or it can be constructed by combining multiple components.

[0084] The shape of the engaging element 5 is arbitrary as long as it has a pressing surface 34, an input-side engaged portion 35, and an output-side engaged portion 36, and can perform the functions described above. In this example, since the engaging element 5 is composed of two engaging elements 5, each engaging element 5 has a substantially semicircular end face shape when viewed from the axial direction and has a shape that is symmetrical with respect to the width direction.

[0085] The engaging element 5 can be manufactured by any method. For example, the engaging element 5 can be manufactured by press punching, sintering, forging, casting, machining, or any combination thereof. From the standpoint of reducing the manufacturing cost of the engaging element 5, it is preferable that the engaging element 5 be manufactured by press punching, as in this example.

[0086] The engaging element 5 may have, as an optional component, convex curved surfaces 37 and 38 on at least one of the parts of the input-side engaged portion 35 that engages with the input-side engaging portion 13, and the output-side engaged portion 36 that engages with the output-side engaging portion 21. In this case, when the reverse input shut-off clutch 1 is operated, the convex curved surface 37 of the input-side engaged portion 35 comes into contact with the radially inner surface 15 of the input-side engaged portion 13, or the convex curved surface 38 of the output-side engaged portion 36 comes into contact with the flat surface 22 of the output-side engaging portion 21. In this case, the contact pressure at the contact point between the input member 3 or output member 4 and the engaging element 5 can be kept low.

[0087] The convex curved surface portion 37 is provided on the radially inward surface 39 of the inner surface of the input-side engaged portion 35, which faces radially outward, in the portion that engages with the input-side engaged portion 13, so as to be convex toward the input-side engaged portion 13. The convex curved surface portion 37 is provided at two locations: a portion that engages with the input-side engaged portion 13 when the input member 3 rotates to one side, and a portion that engages with the input-side engaged portion 13 when the input member 3 rotates to the other side.

[0088] In this example, the radially inner surface 39 of the input-side engaged portion 35 is provided with a convex portion 40 that protrudes radially outward from the adjacent portions on both sides in the second direction, and the convex curved portions 37 are provided at the ends of the convex portion 40 on both sides in the second direction. Furthermore, the convex portion 40 has a connecting surface portion 50 formed by a flat surface perpendicular to the first direction in the second direction intermediate portion between the two convex curved portions 37.

[0089] The cross-sectional shape and radius of curvature of the convex curved surface portion 37 are not particularly limited, as long as they can prevent the contact pressure at the contact point with the input-side engaging portion 13 from becoming excessive. For example, the cross-sectional shape of the convex curved surface portion 37 can be approximately arc-shaped, approximately elliptical, etc. The cross-sectional shape and radius of curvature of the convex curved surface portion 37 can be determined by experiment, simulation, etc.

[0090] The convex curved portion 38 is provided at two locations within the output-side engaging portion 36: the portion that engages with the output-side engaging portion 21 when the output member 4 rotates to one side, and the portion that engages with the output-side engaging portion 21 when the output member 4 rotates to the other side relative to the engaging element 5. The convex curved portion 38 is provided so as to be convex toward the output-side engaging portion 21.

[0091] In this example, the convex curved surface portion 38 is provided at both ends of the output-side engaged portion 36 in the width direction (second direction). The output-side engaged portion 36 also has a connecting surface portion 51 in the width direction intermediate between the two convex curved surface portions 38, which connects the two convex curved surface portions 38 and is formed by a flat surface perpendicular to the radial direction.

[0092] The cross-sectional shape and radius of curvature of the convex curved surface portion 38 are not particularly limited, as long as they can prevent the contact pressure at the contact point with the output-side engaging portion 21 from becoming excessive. For example, the cross-sectional shape of the convex curved surface portion 38 can be approximately arc-shaped, approximately elliptical, etc. The cross-sectional shape and radius of curvature of the convex curved surface portion 38 can be determined by experiment, simulation, etc.

[0093] The engaging element 5 preferably has a convex curved surface portion 37 and a convex curved surface portion 38, as in this example. In particular, in this example, the shape is such that the convex curved surfaces 37 and 38 are simultaneously formed on the engaging element 5, which is formed by pressing and punching a metal plate. Therefore, compared to the case where the convex curved surface portion is provided by machining the contact portion with the engaging element 5 of the input member 3 and output member 4, rather than on the engaging element 5 side, the manufacturing cost of the reverse input blocking clutch 1 can be reduced.

[0094] In this example, the radially outer surface 41 of the inner surface of the input-side engaged portion 35, which faces radially inward, is composed of a curved surface having a substantially arc-shaped contour or a composite surface having a substantially V-shaped contour when viewed from the axial direction. The circumferential surface 42 connecting the radially inner surface 39 and the radially outer surface 41 is composed of a partially cylindrical concave curved surface.

[0095] The output-side engaged portion 36 is provided at the center of the width direction of the radially inner surface of the engaging element 5. The shape of the output-side engaged portion 36 is not limited as long as it is configured to engage with the output-side engaged portion 21. In this example, the output-side engaged portion 36 is provided at the center of the width direction of the radially inner surface of the engaging element 5 so as to protrude radially inward from the portions adjacent to it on both sides in the width direction.

[0096] (Biasing member and holding member) The reverse input blocking clutch 1 in this example further comprises, as optional components, a biasing member 43 and a holding member 44.

[0097] The biasing member 43 elastically biases the engaging element 5 toward the pressed surface 6. The biasing member 43 can be made of a spring such as a leaf spring, coil spring, or disc spring, or an elastic material such as rubber, elastomer, or synthetic resin. The number of biasing members 43 is not particularly limited and is appropriately determined according to the number of engaging elements 5.

[0098] The biasing member 43 elastically biases the engaging element 5 toward the pressed surface 6 by the force that attempts to restore its elasticity. As a result, in the neutral state where no torque is applied to either the input member 3 or the output member 4, the pressing surface 34 of the engaging element 5 comes into contact with the pressed surface 6.

[0099] In this example, the biasing member 43 is composed of two biasing members 43 positioned at two locations in the width direction between the radially inner surfaces of the two engaging elements 5, and each biasing member 43 is composed of a compression coil spring. Each biasing member 43 is fitted and held in the holding hole 47 of the holding member 44, thereby preventing it from falling out from the portion between the two engaging elements 5.

[0100] The retaining member 44 comprises a first spacer portion 45 and a second spacer portion 46 arranged spaced apart in the axial direction, and two connecting portions 48 arranged on both sides of the first spacer portion 45 and the second spacer portion 46 with respect to a second direction, each connecting the first spacer portion 45 and the second spacer portion 46, and each having a retaining hole 47 extending in the first direction.

[0101] The retaining member 44 is attached to the output member 4 with the engaging element 5 positioned between the first spacer portion 45 and the second spacer portion 46 in the axial direction, thereby restricting the axial movement of the engaging element 5 relative to the output member 4. Specifically, the retaining ring 49, which is locked to the small-diameter shaft portion 27 of the output member 4, restricts the movement of the retaining member 44 to one side in the axial direction, and the other side of the second spacer portion 46 is brought into contact with or close to the end face of the output shaft portion 25 on one side in the axial direction, thereby restricting the movement of the retaining member 44 to the other side in the axial direction.

[0102] <Explanation of the operation of the reverse input blocking clutch> The operation of the reverse input blocking clutch 1 in this example will be explained using Figures 3 and 4. Note that Figures 3 and 4 omit the biasing member 43 and the holding member 44, and exaggerate the radial gap between the input member 3 and the output member 4 and the two engaging elements 5.

[0103] When rotational torque is applied to the input member 3, the engaging element 5 moves away from the pressed surface 6, regardless of the rotational direction of the input member 3.

[0104] More specifically, as shown in Figure 3, the input-side engaging portion 13 rotates inside the input-side engaged portion 35 in the rotational direction of the input member 3 (counterclockwise in the example of Figure 3). This reduces the gap between the radial inner surface 15 of the input-side engaging portion 13 and the radial inner surface 39 of the input-side engaged portion 35, causing the radial inner surface 15 of the input-side engaging portion 13 to come into contact with the radial inner surface 39 of the input-side engaged portion 35.

[0105] In this example, the radially inner surface 15 of the input-side engaging portion 13 is brought into contact with one of the two convex curved surfaces 37 provided on the input-side engaged portion 35.

[0106] From this state, as the input member 3 rotates further, the radially inner surface 15 of the input-side engaging portion 13 presses one of the convex curved portions 37 radially inward, causing the engaging element 5 to move away from the pressed surface 6. That is, based on the engagement with the input member 3, the engaging element 5 moves radially inward, moving closer to each other, and engages the output-side engaged portion 36 with the output-side engaging portion 21 of the output member 4. In the case of two engaging elements 5 as in this example, the radially inner surfaces of the two engaging elements 5 move closer to each other, and the output-side engaged portion 21 is sandwiched from both radial sides by the output-side engaged portions 36 of the two engaging elements 5.

[0107] In this way, the output member 4 is rotated so that the flat surface portion 22 of the output-side engaging portion 21 is parallel to the connecting surface portion 51 of the output-side engaged portion 36, while the output-side engaging portion 21 and the output-side engaged portion 36 of the engaging element 5 are engaged without any rattle. As a result, the rotational torque input to the input member 3 is transmitted to the output member 4 via the engaging element 5 and output from the output member 4.

[0108] When rotational torque is input in reverse to the output member 4, the engaging element 5 moves toward the pressed surface 6 regardless of the rotation direction of the output member 4. Specifically, as shown in Figure 4, the output-side engaging portion 21 rotates in the rotation direction of the output member 4 (clockwise in the example of Figure 4). The flat surface portion 22 of the outer circumferential surface of the output-side engaging portion 21 presses the output-side engaged portion 36 radially outward, causing the engaging element 5 to move toward the pressed surface 6. Its pressing surface 34 frictionally engages with the pressed surface 6. In the case of having two engaging elements 5, as in this example, the two engaging elements 5 move radially outward, away from each other, based on their engagement with the output member 4, and the pressing surfaces 34 of the two engaging elements 5 frictionally engage with the pressed surface 6.

[0109] As a result, the rotational torque reversed into the output member 4 is either completely blocked and not transmitted to the input member 3, or only a portion of the rotational torque reversed into the output member 4 is transmitted to the input member 3 and the rest is blocked.

[0110] In order to completely block the rotational torque that is 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 and braced between the output-side engaging part 21 and the pressed member 2 so that the pressing surface 34 of the engaging element 5 does not slide, i.e., rotate relative to the pressed surface 6, thereby locking the output member 4.

[0111] To ensure that only a portion of the rotational torque inverted to the output member 4 is transmitted to the input member 3 and the remainder is blocked, the engaging element 5 is clamped and braced between the output-side engaging portion 21 and the pressed member 2 so that the pressing surface 34 of the engaging element 5 slides, i.e., rotates relative to the pressed surface 6, thereby partially locking the output member 4.

[0112] In the reverse input blocking clutch 1 of this example, the size of the gaps between each component is adjusted so that the above operation is possible. In particular, when the pressing surface 34 of the engaging element 5 is in contact with the pressed surface 6, a gap exists between the radially inner surface 15 of the input-side engaging portion 13 and the convex portion 40 of the input-side engaged portion 35. Furthermore, since the engaging element 5 has a groove 52 on the pressing surface 34, it is possible to appropriately adjust the amount of lubricant interposed between the pressing surface 34 and the pressed surface 6.

[0113] This prevents the radially outward movement of the engaging element 5 from being blocked by the input-side engaging part 13 when rotational torque is input in reverse to the output member 4. Furthermore, even after the pressing surface 34 contacts the pressed surface 6, the surface pressure acting on the contact area between the pressing surface 34 and the pressed surface 6 changes according to the magnitude of the rotational torque input in reverse to the output member 4, thereby ensuring that the output member 4 is properly locked or partially locked. In addition, it reliably prevents the pressing surface 34 from slipping against the pressed surface 6, ensuring that the output member 4 can be reliably locked or partially locked.

[0114] [Second Example] A second example of the embodiment of the present disclosure will be described with reference to Figures 8 to 9C. In this example, each of the two pressing surfaces 34 of the engaging element 5a is provided with two grooves 52a that cross each of the two pressing surfaces 34 in the circumferential direction. The configuration and effects of the other parts of the second example are the same as those of the first example.

[0115] [Third Example] A third example of the embodiment of the present disclosure will be described with reference to Figures 10A to 10C. In this example, grooves 52b formed to cross the circumferential direction on each of the two pressing surfaces 34 of the engaging element 5b are made continuous with each other. The ends of the grooves 52b on the two pressing surfaces 34 that are close to each other are connected by a connecting groove 53. That is, the grooves 52b are composed of the circumferential side portions of a circumferential groove 54 formed over the entire circumferential length of the radially outer surface of the engaging element 5b. The configuration and effects of the other parts of the third example are the same as in the first example.

[0116] [Fourth Example] A fourth example of the embodiments of the present disclosure will be described with reference to Figures 11A and 11B.

[0117] In this example, the grooves 52c are composed of multiple grooves (four on each side in the illustrated example) provided on each of the two pressing surfaces 34 of the engaging element 5c, so as to axially cross each of the two pressing surfaces 34. The axial ends of the grooves 52c open onto the axial sides of the engaging element 5c. As a result, as the engaging element 5 moves radially outward, some of the excess lubricant adhering to the pressing surface 34 or the pressed surface 6 can be reliably released to a portion axially away from the contact point between the pressed surface 6 and the pressing surface 34.

[0118] Furthermore, when forming the engaging element 5c by pressing and punching out a metal plate, the respective grooves 52c can be formed by this punching process. This makes it easier to reduce manufacturing costs.

[0119] The other components and effects of the fourth example are the same as those of the first example.

[0120] The first to fourth embodiments of this disclosure can be combined as appropriate, as long as they do not create any inconsistencies.

[0121] 1 Reverse input blocking clutch 2 Pressed member 3 Input member 4 Output member 5, 5a, 5b, 5c Engaging element 6 Pressed surface 7 Housing element 8 Large diameter cylindrical surface 9 Small diameter cylindrical surface 10 Connecting surface 11 Inward flange 12 Screw hole 13 Input side engaging part 14 Input shaft 15 Radial inner surface 17 Radial outer surface 19 Ridge 20 Input flange 21 Output side engaging part 22 Flat surface 23 Partial cylindrical surface 24 Ridge 25 Output shaft 26 Output flange 27 Small diameter shaft 28 Radial rolling bearing 29 Outer ring 30a, 30b Retaining ring 31 Inner ring 32 Rolling element 33 Sliding bearing 34 Pressing surface 35 Input side engaged part 36 Output side engaged part 37 Convex curved surface portion 38 Convex curved surface portion 39 Radially inner surface portion 40 Convex surface portion 41 Radially outer surface portion 42 Circumferential surface portion 43 Biasing member 44 Holding member 45 First spacer portion 46 Second spacer portion 47 Holding hole 48 Connecting portion 49 Retaining ring 50 Connecting surface portion 51 Connecting surface portion 52, 52a, 52b, 52c Recessed groove 53 Connecting groove portion 54 Circumferential groove

Claims

1. A pressed member having a pressed surface on its inner circumferential surface; an input member having an input-side engaging portion located radially inward of the pressed surface and arranged coaxially with the pressed surface; an output member having an output-side engaging portion located radially inward of the input-side engaging portion and arranged coaxially with the pressed surface; and an engaging element having a pressing surface facing the pressed surface, an input-side engaged portion that can engage with the input-side engaging portion, and an output-side engaged portion that can engage with the output-side engaging portion, and arranged to be movable in the radial direction. The engaging element, when rotational torque is input to the input member, moves radially away from the pressed surface based on the input-side engaging portion engaging with the input-side engaged portion, and transmits the rotational torque input to the input member to the output member by engaging the output-side engaged portion with the output-side engaging portion. Conversely, when rotational torque is input in reverse to the output member, the engaging element presses the pressing surface against the pressed surface based on the output-side engaging portion engaging with the output-side engaged portion, thereby frictionally engaging the pressing surface with the pressed surface. The engaging element has a groove that crosses the pressing surface, and is a reverse input blocking clutch.

2. The reverse input blocking clutch according to claim 1, wherein the groove extends in the circumferential direction.

3. The reverse input shutoff clutch according to claim 2, wherein the pressing surface is composed of two pressing surfaces provided at two positions spaced apart from each other in the circumferential direction, and each of the two pressing surfaces is provided with the groove.

4. The reverse input blocking clutch according to claim 3, wherein the grooves provided on each of the two pressing surfaces are not continuous with each other.

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