Cam clutch

Abstract

To provide a cam clutch that has a simple structure, is in excellent in accuracy, stability and durability and can achieve downsizing and long service life, and that comprises a torque limiter function capable of handling even high torque.SOLUTION: A cam clutch comprises a plurality of cams 130 provided in a circumferential direction between at least one set of inner ring 110 and outer ring 120 provided coaxially in a relatively rotatable manner, and bias means for biasing the plurality of cams 130 in a direction in which they are brought into contact with the inner and outer rings 110, 120. The cam 130 has an inclination restriction unit 133 that restricts an inclination in a meshing direction by contacting a locking part 141 provided on the inner ring 110 and the outer ring 120 other than cam receiving surfaces 111, 121.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a cam clutch having a torque limiter function. [Background technology]

[0002] 2. Description of the Related Art Among clutches that transmit or cut off torque from an input shaft side to an output shaft side, there are known ones that are provided with a torque limiter for preventing excessive torque from being transmitted.

[0003] Known torque limiters include so-called friction-type torque limiters that use a tolerance ring or a friction plate, and so-called mechanical-type torque limiters that use, for example, a ball and a biasing means that applies a load to the ball in the axial or radial direction. The biasing means may be, for example, a coil spring, a disc spring, or a leaf spring.

[0004] For example, Patent Document 1 discloses a torque limiter in which a tolerance ring is arranged between the outer peripheral surface of an outer ring and the inner peripheral surface of an input transmission member or between the outer peripheral surface of an inner ring and the outer peripheral surface of an input transmission member, and in the event of input of torque exceeding a specified torque, slippage occurs between the inner ring, the outer ring, or the input transmission member and the tolerance ring, thereby limiting the transmission of torque.

[0005] Furthermore, for example, Patent Document 2 discloses a torque limiter in which a circular leaf spring is provided to apply a force to one side to a ball inserted into a hole, and in the event of excessive torque input, for example, the leaf spring elastically deforms in the expanding direction, pushing the ball out of the hole, thereby limiting the transmission of torque. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2021-156432 A [Patent Document 2] Special Publication No. 2005-505431 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, friction-type torque limiters such as the torque limiter described in Patent Document 1 are often highly dependent on the friction coefficient of the friction plates, etc., and slide when tripping (when torque transmission is cut off). Therefore, in clutches equipped with such torque limiters, it is difficult to control the load in response to environmental changes, and repeated tripping can cause concerns about durability due to wear and instability of the limiter load. Furthermore, in mechanical torque limiters such as the torque limiter described in Patent Document 2, it is difficult to generate high torque using a leaf spring or the like used as the biasing means, and since a large space is required to place the biasing means, it is not suitable for power transmission applications in vehicles that require high torque and space saving, and there are problems such as an increase in the number of parts and an increase in manufacturing costs. Furthermore, alignment of the leaf spring is also required.

[0008] On the other hand, it is conceivable to use an upper limit of the meshing torque, which is determined by the cam shape of the cam clutch, as a torque limiter by causing the cam surface to slip when the torque exceeds the upper limit. For example, as shown in FIG. 1, when the rated torque load is applied, the inner cam surface 531 of the cam 530 meshes with the inner cam receiving surface 511 and the outer cam receiving surface 521, acting as a wedge to transmit torque, but when excessive input is applied, the cam 530 tilts and exceeds the upper limit of the meshing torque, exceeding the wedge angle limit of the R-shape at which the cam transmits torque. When this wedge angle limit is exceeded, in the case of a cam surface shape like that shown in the upper part of Figure 1, the contact point between the cam and the cam receiving surface moves instantaneously, the wedge angle effect is lost, the torque is released (rollover), and a large impact occurs. In addition, when the torque limiter function was activated, the angle limit was exceeded due to rollover, so it did not return to its original state but only operated once, necessitating the replacement of the entire cam clutch (or disassembly and reassembly, etc.).

[0009] Furthermore, as shown in the lower part of Figure 1, if there is a surface that slides against the cam receiving surface on the extension of the wedge angle limit to prevent rollover after the wedge angle limit is exceeded, the cam and cam surface will slide after the static friction limit is exceeded at the wedge angle limit position, and the torque will suddenly drop. At this time, a phenomenon known as pop-out occurs in which the cam suddenly returns in the direction of the no-load state, posing a risk of damage occurring due to the collision between the cam and the cam receiving surface.

[0010] The present invention has been made based on the above circumstances, and aims to provide a cam clutch with a torque limiter function that has a simple structure, is accurate, stable, and durable, can be made compact and has a long life, and can also handle high torque. [Means for solving the problem]

[0011] The present invention solves the above problem by providing a cam clutch comprising at least one set of inner and outer rings arranged coaxially and rotatably relative to one another, a plurality of cams arranged in the circumferential direction between the inner and outer rings, and a biasing means for biasing the plurality of cams in a direction to contact the inner and outer rings, wherein the cams have a tilt limiting portion that abuts against an engagement portion arranged other than the cam receiving surfaces of the inner and outer rings to limit tilting in the meshing direction. Effect of the Invention

[0012] According to the invention of claim 1, the cam has a tilt limiting portion that abuts against an engaging portion provided other than the cam receiving surface of the inner and outer rings to limit tilting in the meshing direction. This limits the engagement of the cam to a tilting state corresponding to an arbitrary torque just before the upper limit of the engagement torque which depends on the cam shape, thereby making it possible to accurately set the upper limit of the transmission torque as a torque limiter. In addition, design freedom is increased, and the wedge angle limit of the R-shape that transmits torque from the cam is not exceeded, and the wedge angle is not suddenly changed by instantaneous movement to the slip plane to release the torque. Therefore, even when the torque limit is exceeded, the torque does not suddenly release, and a decrease in durability due to pop-out can be suppressed. Furthermore, since the engagement portion is provided other than on the cam receiving surfaces of the inner and outer rings, it is possible to reduce wear and sliding on the cam receiving surfaces of the inner and outer rings, thereby making it possible to improve durability.

[0013] According to the configuration described in claim 2, since the locking portion is provided on a cage member that supports and aligns multiple cams in the circumferential direction, the locking portion can be provided at a position on the extended portion of the cam surface that does not contact the cam receiving surfaces of the inner and outer rings, and it is possible to provide the locking portion and tilt limiting portion that constitute the torque limiter without increasing the overall axial length of the cam clutch. Furthermore, by making the cage member movable radially relative to the inner and outer rings, even if the axes of the inner and outer rings are misaligned and the tilting state of the multiple cams is no longer uniform, the cage member can move radially to keep the upper limit torque of the multiple cams uniform, and the upper limit of the transmitted torque can be set even more accurately.

[0014] According to the configuration described in claim 3, since the tilt limiting portion is provided at one or both axial ends of the cam, it becomes possible to form the tilt limiting portion independently of the shape design of the cam surface, thereby improving design freedom and enabling the tilt to be set with high precision and the upper limit of the transmission torque as a torque limiter to be set with even higher precision. According to the configuration described in claim 4, since the locking portion is provided on the regulating member that is fitted into the outer ring or the inner ring from the axial side, different upper torque limits can be set by changing the regulating member using the same inner ring, outer ring, and cam. In addition, even if the engaging portion deteriorates due to wear or the like, by replacing the restricting member, it is possible to maintain a stable upper limit of torque for a long period of time. [Brief description of the drawings]

[0015] [Figure 1] FIG. 13 is an explanatory diagram of the operation of a conventional cam clutch when excessive torque is input. [Diagram 2] 1 is a perspective view of a cam clutch according to a first embodiment of the present invention; [Diagram 3] FIG. 3 is a perspective view of FIG. 2 with the outer ring and inner ring removed. [Figure 4] FIG. 3 is a partially sectional perspective view of FIG. 2. [Diagram 5] FIG. 3 is an enlarged perspective view of the cam and cage of FIG. 2. [Figure 6] 5 is an explanatory diagram of the operation of the cam clutch according to the first embodiment when an excessive torque is input; FIG. [Figure 7] FIG. 4 is a partial cross-sectional perspective view of a first modified example of the cam clutch according to the first embodiment. [Figure 8] FIG. 6 is a partially sectional perspective view of a second modified example of the cam clutch according to the first embodiment. [Figure 9] FIG. 6 is a perspective view of a cam clutch according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view of FIG. 9 with the outer ring removed. [Figure 11] FIG. 10 is a partially sectional perspective view of FIG. [Figure 12] FIG. 7 is a partially sectional perspective view of a cam clutch according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a partially sectional perspective view of a cam clutch according to a fourth embodiment of the present invention. [Figure 14] FIG. 11 is a partially sectional perspective view of a cam clutch according to a fifth embodiment of the present invention. [Figure 15] FIG. 15 is a partially sectional perspective view taken from a different viewpoint than in FIG. 14 . [Figure 16]FIG. 13 is a partially sectional perspective view of a cam clutch according to a sixth embodiment of the present invention. [Figure 17] FIG. 13 is a perspective view of a cam clutch according to a seventh embodiment of the present invention. [Figure 18] FIG. 18 is a perspective view of FIG. 17 with the outer ring removed. [Figure 19] FIG. 18 is a partially sectional perspective view of FIG. [Figure 20] FIG. 18 is a partially sectional perspective view taken from a different viewpoint than in FIG. 17 . [Figure 21] FIG. 13 is a perspective view of a cam clutch according to an eighth embodiment of the present invention. [Figure 22] FIG. 22 is a perspective view of FIG. 21 with the outer and inner rings removed. [Diagram 23] FIG. 22 is a partially sectional perspective view of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] First Embodiment As shown in Figures 1 to 4, the cam clutch 100 according to the first embodiment of the present invention comprises an inner ring 110 and an outer ring 120 arranged coaxially and rotatable relative to each other, a plurality of cams 130 arranged in the circumferential direction between the inner ring 110 and the outer ring 120 to transmit torque, and a biasing means (garter springs) 150 that biases the multiple cams 130 in a direction to contact the inner and outer rings 110, 120. The multiple cams 130 are aligned and supported in the circumferential direction by a cage member 140 . The cam 130 has a tilt limiting portion 133 that abuts against a locking portion 141 of the cage member 140 to limit the tilt in the meshing direction.

[0017] The operation of the torque limiter function of the cam clutch 100 configured as above will be described. As shown in FIG. 6, when a rated torque load is applied, the inner cam surface 131 of the cam 130 meshes with the inner cam receiving surface 111 and the outer cam receiving surface 121 and acts as a wedge to transmit torque. When the transmitted torque reaches a predetermined torque, the back surface on the opposite circumferential side of the tilt regulating portion 133 of the cam 130 abuts against the frame end 142 of the cage member 140, and the tilt regulating portion 133 of the cam 130 abuts against the engagement portion 141 of the cage member 140, preventing further tilting of the cam 130 and suppressing further jamming.By this, when further torque is applied, slippage occurs between the cam receiving surface 111 of the inner ring 110 and the cam surface 132 of the cam 130, or between the cam receiving surface 121 of the outer ring 120 and the cam surface 131 of the cam 130, and the torque is released. Furthermore, as in the modified example shown in Figure 7 (a: partial cross-sectional oblique view, b: explanatory diagram with the inner and outer rings omitted), when the cage member 140 is fixed in the rotational direction relative to the outer ring 120, further tilting of the cam 130 can be prevented simply by the back surface on the circumferentially opposite side of the tilt control portion 133 of the cam 130 abutting the frame end 142 of the cage member 140, and in this case, the back surface is the tilt control portion and the frame end 142 of the cage member 140 is the engagement portion. Furthermore, as in another modified example shown in Figure 8 (a: partial cross-sectional oblique view, b: explanatory diagram with the inner and outer rings omitted), a pressing piece 152 that constantly urges the cam 130 toward the frame end 142 may be provided in correspondence with each cam 130 on a cage member 140 fixed in the rotational direction relative to the outer ring 120, and this may serve as a urging means for urging the cam 130 in a direction that brings it into contact with the inner and outer rings 110, 120. The pressing piece 152 may be a separate piece from the cage member 140, or may be formed integrally with the cage member 140 by constructing the cage member 140 from a spring material.

[0018] <Second embodiment> As shown in Figures 9 to 11, the cam clutch 100b according to the second embodiment of the present invention comprises an inner ring 110b and an outer ring 120b arranged coaxially and rotatable relative to each other, a plurality of cams 130b arranged in the circumferential direction between the inner ring 110b and the outer ring 120b to transmit torque, and a biasing means (garter spring) 150b that radially biases the plurality of cams 130b. The plurality of cams 130b are shaped to have a continuous circumferential surface in addition to the cam surface, and in this embodiment are configured to be self-alignable without a cage member, although a cage member may be present. The cam 130b has tilt limiting portions 133b on both sides thereof that come into contact with locking portions 121b provided on the outer ring 120b to limit tilting in the meshing direction.

[0019] In this cam clutch 100b, when the transmission torque reaches a predetermined torque, the tilt restriction portion 133b of the cam 130b abuts against the engagement portion 121b of the outer ring 120b, preventing further tilting of the cam 130b and suppressing further engagement. As a result, when further torque is applied, slippage occurs between the cam receiving surface of the inner ring 110b and the cam surface of the cam 130b, or between the cam receiving surface of the outer ring 120b and the cam surface of the cam 130b, and the torque is released.

[0020] <Third embodiment> As shown in FIG. 12, the cam clutch 100c according to the third embodiment of the present invention comprises an inner ring 110c and an outer ring 120c arranged coaxially and rotatable relative to each other, a plurality of cams 130c arranged circumferentially between the inner ring 110c and the outer ring 120c to transmit torque, and a biasing means (garter spring) 150c that radially biases the plurality of cams 130c. The plurality of cams 130c are shaped to have a continuous circumferential surface in addition to the cam surface, and are configured to be self-alignable without the need for a cage member. The cam 130c has tilt limiting portions 133b on both sides thereof that come into contact with the restricting members 160c constituting the locking portions to limit the tilting in the meshing direction. The restricting members 160c are annular and are inserted inside both side portions of the outer ring 120c.

[0021] In this cam clutch 100c, when the transmission torque reaches a predetermined torque, the tilt regulating portion 133c of the cam 130c abuts against the regulating member 160c, preventing further tilting of the cam 130c and suppressing further engagement. Therefore, when further torque is applied, slippage occurs between the cam receiving surface of the inner ring 110c and the cam surface of the cam 130c, or between the cam receiving surface of the outer ring 120c and the cam surface of the cam 130c, and the torque is released.

[0022] <Fourth embodiment> As shown in FIG. 13, the cam clutch 100d according to the fourth embodiment of the present invention includes an inner ring 110d and an outer ring 120d arranged coaxially and rotatably relative to each other, a plurality of cams 130d arranged circumferentially between the inner ring 110d and the outer ring 120d to transmit torque, and a biasing means (garter spring) 150d that radially biases the plurality of cams 130d. The plurality of cams 130d are shaped to have a continuous circumferential surface in addition to the cam surface, and in this embodiment are configured to be self-alignable without a cage member, although a cage member may be present. The cam 130d has tilt limiting portions 133d on both sides thereof that come into contact with restricting members 160d constituting an engagement portion to limit tilting in the meshing direction. The restricting members 160d are annular and are press-fitted into the insides of both side portions of the outer ring 120d.

[0023] In this cam clutch 100d, when the transmission torque reaches a predetermined torque, the tilt regulating portion 133d of the cam 130d abuts against the regulating member 160d, preventing further tilting of the cam 130d and suppressing further engagement. Therefore, when further torque is applied, slippage occurs between the cam receiving surface of the inner wheel 110d and the cam surface of the cam 130d, or between the cam receiving surface of the outer wheel 120d and the cam surface of the cam 130d, and the torque is released.

[0024] <Fifth embodiment> As shown in Figures 14 and 15, the cam clutch 100e according to the fifth embodiment of the present invention comprises an inner ring 110e and an outer ring 120e arranged coaxially and rotatable relative to each other, a plurality of cams 130e arranged circumferentially between the inner ring 110e and the outer ring 120e to transmit torque, and a biasing means (garter spring) 150e that radially biases the plurality of cams 130e. The plurality of cams 130e are shaped to have a continuous circumferential surface in addition to the cam surface, and in this embodiment are configured to be self-alignable without a cage member, although a cage member may be present. The cam 130e has a tilt limiting portion 133e on one side thereof that abuts against a locking portion 121e provided on the outer ring 120e to limit tilt in the meshing direction.

[0025] In this cam clutch 100e, when the transmission torque reaches a predetermined torque, the tilt regulating portion 133e of the cam 130e abuts against the engaging portion 121e of the outer wheel 120e, preventing further tilting of the cam 130e and suppressing further engagement. Therefore, when further torque is applied, slippage occurs between the cam receiving surface of the inner wheel 110e and the cam surface of the cam 130e, or between the cam receiving surface of the outer wheel 120e and the cam surface of the cam 130e, and the torque is released.

[0026] Sixth embodiment As shown in FIG. 16, the cam clutch 100f according to the sixth embodiment of the present invention includes an inner ring 110f and an outer ring 120f arranged coaxially and rotatably relative to each other, a plurality of cams 130f arranged in the circumferential direction between the inner ring 110f and the outer ring 120f to transmit torque, and a biasing means (garter spring) 150f that radially biases the plurality of cams 130f. The plurality of cams 130f are shaped to have a continuous circumferential surface in addition to the cam surface, and in this embodiment are configured to be self-alignable without a cage member, although a cage member may be present. The cam 130f has a tilt limiting portion 133f on one side thereof that abuts against a restricting member 160f constituting an engagement portion to limit tilting in the meshing direction. The restricting member 160f has an annular shape and is inserted inside one side of the outer ring 120f. The cam 130f is biased on the other side by a biasing means (garter spring) 150f.

[0027] In this cam clutch 100f, when the transmitted torque reaches a predetermined torque, the tilt regulating portion 133f of the cam 130f abuts against the regulating member 160f that constitutes the engagement portion, preventing further tilting of the cam 130f and suppressing further engagement. As a result, when further torque is applied, slippage occurs between the cam receiving surface of the inner wheel 110f and the cam surface of the cam 130f, or between the cam receiving surface of the outer wheel 120f and the cam surface of the cam 130f, and the torque is released.

[0028] Seventh embodiment As shown in Figures 17 to 20, the cam clutch 100g according to the seventh embodiment of the present invention comprises an inner ring 110g and an outer ring 120g arranged coaxially and rotatable relative to each other, a plurality of cams 130g arranged circumferentially between the inner ring 110g and the outer ring 120g to transmit torque, and a biasing means (garter spring) 150g that radially biases the plurality of cams 130g. The plurality of cams 130g are shaped to have a continuous circumferential surface in addition to the cam surface, and in this embodiment are configured to be self-alignable without a cage member, although a cage member may be present. The cam 130g has a tilt limiting portion 133g on one side thereof that abuts against a locking portion 111g provided on the inner ring 110g to limit tilt in the meshing direction.

[0029] In this cam clutch 100g, when the transmitted torque reaches a predetermined torque, the tilt regulating portion 133g of the cam 130g abuts against the regulating member 160g that constitutes the engagement portion, preventing further tilting of the cam 130g and suppressing further engagement. As a result, when further torque is applied, slippage occurs between the cam receiving surface of the inner ring 110g and the cam surface of the cam 130g, or between the cam receiving surface of the outer ring 120g and the cam surface of the cam 130g, and the torque is released.

[0030] Eighth embodiment As shown in Figures 21 to 23, the cam clutch 100h according to the eighth embodiment of the present invention comprises an inner ring 110h and an outer ring 120h that are coaxially arranged so as to be rotatable relative to each other, a plurality of cams 130h that are arranged in the circumferential direction between the inner ring 110h and the outer ring 120h to transmit torque, and a biasing means (garter spring) 150h that radially biases the plurality of cams 130h. The multiple cams 130h are aligned and supported in the circumferential direction by a cage member 140h. The cam 130h has a tilt limiting portion 133h that abuts against a locking portion 141h of the cage member 140h to limit the tilt in the meshing direction.

[0031] In this cam clutch 100h, when the transmission torque reaches a predetermined torque, the tilt restriction portion 133h of the cam 130h abuts against the engagement portion 141h of the cage member 140h, preventing further tilting of the cam 130h and suppressing further engagement. Therefore, when further torque is applied, slippage occurs between the cam receiving surface of the inner ring 110h and the cam surface of the cam 130h, or between the cam receiving surface of the outer ring 120h and the cam surface of the cam 130h, and the torque is released.

[0032] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the present invention described in the claims. For example, in each of the above embodiments, the configuration may be such that the inner ring is fixed and the outer ring is rotated, the outer ring is fixed and the inner ring is rotated, or both the inner ring and the outer ring are rotated. [Explanation of symbols]

[0033] 100 ··· Cam clutch 110... Inner circle 111, 511 Cam receiving surface 112 .... Locking portion 120 Outer ring 121, 521 Cam receiving surface 122 .... Locking portion 123 .... Cutout 130, 530... Cam 131 Cam surface (outer ring side) 132 Cam surface (inner ring side) 133 Tilt control section 140, 540 ... cage member 141 .... Locking portion 142 ... Frame edge 150 ··· Urging member (garter spring) 151 .... Locking portion 152 Pressing piece 160 Regulating member

Claims

1. A cam clutch comprising at least one pair of inner and outer rings arranged coaxially and relatively rotatably, a plurality of cams arranged in a circumferential direction between the inner and outer rings, and a biasing means for biasing the plurality of cams in a direction to bring them into contact with the inner and outer rings, A cam clutch with a torque limiter function, characterized in that the cam has a tilt limiting portion that abuts against an engagement portion provided other than on the cam receiving surfaces of the inner and outer rings to limit tilting in the meshing direction.

2. 2. The cam clutch with a torque limiter function according to claim 1, wherein the engaging portion is provided on a cage member that supports the plurality of cams in alignment in the circumferential direction.

3. The tilt limiting portion is provided at one or both axial ends of the cam, 2. The cam clutch with a torque limiter function according to claim 1, wherein the engaging portion is provided directly or indirectly on the outer ring or the inner ring.

4. 3. The cam clutch with a torque limiter function according to claim 2, wherein the locking portion is provided on a restricting member that is fitted to the outer ring or the inner ring from a side in the axial direction.

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