cam clutch

Abstract

A cam-type clutch is provided, featuring a torque limiting function. It is adaptable to high torque applications with a simple structure, excellent accuracy, stability, and durability, and can be miniaturized for extended service life. The cam-type clutch comprises: multiple cams arranged circumferentially between at least one pair of inner and outer rings, which are coaxial and rotatable relative to each other; and preloading devices for preloading the multiple cams so that they come into contact with the inner and outer rings. Each cam has an inclination limiting section that restricts the cam's inclination in an engagement direction by coming into contact with a locking section located in a different section of the cam-type clutch than the cam-receiving surfaces of the inner and outer rings.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a cam clutch with a torque limiter function. 2. Description of the related prior art

[0002] As clutches that transmit torque from an input shaft to an output shaft or to terminate the transmission, clutches are known that include a torque limiter to prevent the transmission of excessive torque.

[0003] Known torque limiters include, for example, so-called friction-type torque limiters, which use a tolerance ring or friction plate, and so-called mechanical torque limiters, which use a ball and preload devices to apply a load to the ball in the axial or radial direction. A coil spring, a disc spring, a leaf spring, or the like serves as the preload device.

[0004] Japanese Patent Application Publication 2021-156432, for example, discloses a torque limiter in which a tolerance ring is disposed between an outer peripheral surface of an outer ring and an inner peripheral surface of an input transmission member, or between an outer peripheral surface of an inner ring and an outer peripheral surface of an input transmission member. The torque limiter is configured such that, when a torque higher than a specified torque is applied, slippage occurs between the tolerance ring and the inner ring, the outer ring, or the input transmission member to limit the torque transmission.

[0005] The Japanese translation of PCT Application No. 2005-505431 also discloses a torque limiter with a circular leaf spring designed to exert a force on a ball inserted into a hole in one direction. The torque limiter is designed so that, for example, in the event of excessive torque, the leaf spring elastically deforms in an opening-increasing direction, forcing the ball out of the hole to limit the transmission of torque. OVERVIEW OF THE INVENTION

[0006] However, most friction torque limiters, such as the one described in Japanese Patent Application No. 2021-156432, largely depend on the friction coefficient of the friction plate or similar device and slip at the time of release (when torque transmission is cut off). Accordingly, a clutch with such a torque limiter has difficulty controlling the load due to environmental changes, and repeated release raises concerns about durability and instability of the limiter load due to wear.

[0007] Furthermore, mechanical torque limiters, such as the one described in the Japanese translation of PCT Application No. 2005-505431, have difficulty generating high torque when using a leaf spring or the like as the preload device, and require a large amount of space to install the preload device. Accordingly, such mechanical torque limiters are unsuitable for transmitting drive power in a vehicle that requires high torque and space savings. Another problem is that the number of components increases and production costs increase. Furthermore, positioning of the leaf spring is required.

[0008] On the other hand, it is conceivable to construct a torque limiter by using an upper limit of the engagement torque determined by the cam shape of a cam clutch and causing a cam surface to slide when the torque exceeds the upper limit.

[0009] As in Fig. 1, for example, when a rated torque is applied, a cam 530 engages an inner ring cam receiving surface 511 and an outer ring cam receiving surface 521 and serves as a wedge, and an inner ring side cam surface 531 of the cam 530 transmits the torque, but the cam 530 tilts when excessive torque is applied, and when the torque exceeds the upper limit of the engagement torque, the cam tilts beyond a wedge angle limit of an R-shape of the cam, which transmits the torque.

[0010] If the cam surface has a shape like that shown in the upper part of Fig. As shown in Figure 1, when the cam tilts beyond the wedge angle limit, the contact points between the cam and the cam receiving surfaces move instantly, and the wedge angle effect is lost. This releases the torque (rollover) and creates a strong shock.

[0011] In addition, if the cam lobe tilts beyond the angle limit during a rollover, it will not return to its original position when acting as a torque limiter. Therefore, the torque limiter only works once, and the entire cam clutch must be replaced (or, for example, disassembled and reassembled).

[0012] As in the lower part of Fig. 1, in order to prevent rollover after the cam inclines beyond the wedge angle limit, in a case where a surface adapted to slide against a cam receiving surface is provided to extend from the wedge angle limit, when friction exceeds a stiction limit at the wedge angle limit position, the cam and the cam surface slide and torque is suddenly released.

[0013] At this time, a phenomenon (pop-out) occurs in which the cam suddenly returns to the state where no load is applied to it, and there is a problem that damage may occur at this time due to collision between the cam and the cam receiving surface.

[0014] The present invention has been made under the above circumstances and has an object to provide a cam clutch having a torque limiting function, adaptable to high torque with a simple structure, excellent accuracy, stability and durability, and which can be downsized and can have an increased service life.

[0015] The present invention solves the above problem with a cam clutch comprising: at least one pair of an inner ring and an outer ring which are coaxial with each other and rotatable relative to each other; a plurality of cams arranged in a circumferential direction between the inner ring and the outer ring; and biasing means for biasing the plurality of cams to come into contact with the inner ring and the outer ring, wherein each of the cams has an inclination limiting portion which limits the inclination of the cam in an engagement direction by coming into contact with a locking portion provided in a portion of the cam clutch other than the cam receiving surfaces of the inner ring and the outer ring.

[0016] In the invention according to claim 1, each cam has the inclination limiting portion that limits the inclination in the engagement direction by contacting with the locking portion provided in a portion other than the cam receiving surfaces of the inner ring and the outer ring. With this configuration, the engagement of the cams is limited to an inclined state corresponding to an appropriate torque lower than an upper limit of the engagement torque depending on the shape of the cams, so that an upper limit of the transmitted torque for the cam clutch serving as a torque limiter can be accurately set.

[0017] In addition, this formation increases design freedom, prevents the cams from being tilted beyond the wedge angle limit of their R-shape that transmits torque, and prevents a situation where torque is released as a result of a sudden change in the wedge angle due to an instantaneous movement from contact points to a surface on which slippage occurs, and accordingly, even if the torque exceeds the torque limit, the torque is not suddenly released, and a reduction in durability due to pop-out can be avoided.

[0018] Furthermore, the locking portion is provided in a different area than the cam receiving surfaces of the inner and outer rings. Therefore, it is possible to prevent sliding caused by wear of the cam receiving surfaces of the inner and outer rings and increase durability.

[0019] According to the embodiment described in claim 2, the locking portion is provided in a cage member that supports and circumferentially arranges the plurality of cams. Accordingly, the locking portion can be provided at a position where it does not come into contact with the cam receiving surfaces of the inner ring and the outer ring in a region extending from the cam surfaces, and it is possible to provide the locking portion and the inclination limiting portion, which constitute the torque limiter, without increasing the overall length of the cam clutch in the axial direction.

[0020] When the cage member is formed to be movable in the radial direction relative to the inner ring and the outer ring, even if the plurality of cams incline unevenly due to a displacement of the axes of the inner ring and the outer ring, the upper limit torque can be kept uniform due to the movement of the cage member in the radial direction, and accordingly, it is possible to adjust the upper limit of the transmitted torque more accurately.

[0021] According to the embodiment described in claim 3, the inclination limiting portion is provided in one end region or two end regions of the cam in the axial direction. This embodiment makes it possible to form the inclination limiting portion independently of the shape of the cam surface, increasing design freedom, and furthermore makes it possible to more accurately adjust the inclination and the upper limit of the transmitted torque for the cam clutch acting as a torque limiter. According to the embodiment described in claim 4, the locking portion is provided in a limiting member that is attached to the outer ring or the inner ring from one side in the axial direction. This embodiment makes it possible to set the upper limit of the torque to different values ​​by exchanging the limiting member, while using the same inner ring, outer ring, and cams.

[0022] Even if the locking portion deteriorates due to wear or the like, it is possible to maintain the upper limit of torque stable over a long period of time by replacing the limiting element. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a diagram showing the operation of conventional cam clutches when excessive torque is applied; Fig. 2 shows a perspective view of a cam clutch according to a first embodiment of the present invention; Fig. 3 is a perspective view of the Fig. 2, from which an outer ring and an inner ring have been removed; Fig. 4 shows a partially cross-sectional perspective view of the Fig. 2 shown cam clutch; Fig. 5 is an enlarged perspective view of a Fig. 2 shown cam and a cage; Fig. 6 is a diagram showing the operation of the cam clutch according to the first embodiment when excessive torque is applied; Fig. 7A and Fig. 7B are partial perspective cross-sectional views of a first variant of the cam clutch according to the first embodiment; Fig. 8A and Fig. 8B are partial perspective cross-sectional views of a second variant of the cam clutch according to the first embodiment; Fig. 9 shows a perspective view of a cam clutch according to a second embodiment of the present invention; Fig. 10 is a perspective view of the Fig. 9, from which an outer ring and an inner ring have been removed; Fig. 11 shows a partially sectioned perspective view of the Fig. 9 shown cam clutch; Fig. 12 is a partially cross-sectional perspective view of a cam clutch according to a third embodiment of the present invention; Fig. 13 is a partially cross-sectional perspective view of a cam clutch according to a fourth embodiment of the present invention; Fig. 14 is a partially cross-sectional perspective view of a cam clutch according to a fifth embodiment of the present invention; Fig. 15 shows a partially cross-sectional perspective view of the Fig. 14 shown cam clutch from a different angle; Fig. 16 is a partially cross-sectional perspective view of a cam clutch according to a sixth embodiment of the present invention; Fig. 17 is a perspective view of a cam clutch according to a seventh embodiment of the present invention; Fig. 18 is a perspective view of the Fig. 17, from which an outer ring is removed; Fig. 19 shows a partially sectioned perspective view of the Fig. 17 shown cam clutch; Fig. 20 shows a partially sectioned perspective view of the Fig. 17 shown cam clutch from a different angle; Fig. 21 shows a perspective view of a cam clutch according to a third embodiment of the present invention; Fig. 22 is a perspective view of the Fig. 21, from which an outer ring and an inner ring have been removed; and Fig. 23 shows a partially cross-sectional perspective view of the Fig. 21 shown cam clutch. DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

[0023] As shown in Figs. 2 to 5, a cam clutch 100 according to a first embodiment of the present invention includes an inner ring 110 and an outer ring 120 coaxial with each other and rotatable relative to each other, a plurality of cams 130 circumferentially disposed between the inner ring 110 and the outer ring 120 to transmit torque, and biasing means (coil spring) 150 for biasing the plurality of cams 130 to come into contact with the inner ring 110 and the outer ring 120.

[0024] The plurality of cams 130 are supported and lined up in the circumferential direction by a cage part 140.

[0025] Each cam 130 has an inclination limiting portion 133 that limits the inclination in an engagement direction by coming into contact with a locking portion 141 of the cage member 140.

[0026] The following describes the operation of a torque limiter function of the cam clutch 100 in the embodiment described above.

[0027] As in Fig. 6, when the rated torque is applied, each cam 130 engages an inner ring cam receiving surface 111 and an outer ring cam receiving surface 121 and serves as a wedge, and an inner ring side cam surface 131 of the cam 130 transmits the torque.

[0028] When the transmitted torque reaches a predetermined torque, a rear surface of each cam 130, which is opposite to the inclination limiting portion 133 in the circumferential direction, comes into contact with a frame edge 142 of the cage member 140, and the inclination limiting portion 133 of the cam 130 comes into contact with the locking portion 141 of the cage member 140. This prevents further inclination of the cam 130 to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between the cam receiving surface 111 of the inner ring 110 and a 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.

[0029] Even in a case where the cage member 140 is fixed in the direction of rotation relative to the outer ring 120, as in a case shown in the Fig. 7A and Fig. In the variant shown in FIG. 7B (FIG. 7A: partial perspective cross-sectional view, FIG. 7B: diagram in which the inner ring and the outer ring are omitted), it is possible to prevent further inclination of the cam 130 with only the configuration in which the rear surface of the cam 130, which is opposite to the inclination limiting portion 133 in the circumferential direction, comes into contact with the frame edge 142 of the cage member 140. In this case, the rear surface serves as the inclination limiting portion, and the frame edge 142 of the cage member 140 serves as the locking portion.

[0030] In addition, as in another, in the Fig. 8A and Fig. 8B (8A: partial perspective cross-sectional view, 8B: diagram in which the inner ring and the outer ring are omitted), a pressure piece 152 that always biases a cam 130 toward the frame edge 142 may be provided in correspondence with each cam 130 on the cage member 140 fixed in the rotational direction relative to the outer ring 120, and the pressure piece 152 may be used as biasing means for biasing the cam 130 so that it comes into contact with the inner ring 110 and the outer ring 120.

[0031] The pressure piece 152 may be separate from the cage member 140, or the cage member 140 may be formed from a spring material and the pressure piece 152 and the cage member 140 may be formed as a single piece. Second embodiment

[0032] As in the Fig. 9 to 11, a cam clutch 100 according to a second embodiment of the present invention includes an inner ring 110b and an outer ring 120b coaxial with each other and rotatable relative to each other, a plurality of cams 130b circumferentially disposed between the inner ring 110b and the outer ring 120b to transmit torque, and biasing means (coil spring) 150b for biasing the plurality of cams 130b in the radial direction.

[0033] The plurality of cams 130b in the present embodiment each have a continuous circumferential surface different from the cam surfaces and can be self-aligned without using a cage member, but a cage member may also be provided.

[0034] Inclination limiting portions 133b are provided in two side regions of each cam 130b and limit the inclination in an engagement direction by coming into contact with locking portions 121b provided in the outer ring 120b.

[0035] In this cam clutch 100b, the inclination limiting portions 133b of the cams 130b come into contact with the locking portions 121b of the outer ring 120b. This prevents further inclination of the cams 130b to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between a cam receiving surface of the inner ring 110b and a cam surface of the cams 130b, or between a cam receiving surface of the outer ring 120b and cam surfaces of the cams 130b, and the torque is released. Third embodiment

[0036] As in Fig. 12, a cam clutch 100c according to a third embodiment of the present invention includes an inner ring 110c and an outer ring 120c coaxial with each other and rotatable relative to each other, a plurality of cams 130c circumferentially disposed between the inner ring 110c and the outer ring 120c to transmit torque, and biasing means (coil spring) 150c for biasing the plurality of cams 130c in the radial direction.

[0037] The plurality of cams 130c each have a continuous circumferential surface different from the cam surfaces and can be self-aligned without using a cage member.

[0038] Inclination limiting portions 133c are provided in two side regions of each cam 130c and limit the inclination in an engagement direction by coming into contact with limiting members 160c forming locking portions.

[0039] The limiting elements 160c are ring-shaped and inserted into the inside of two side regions of the outer ring 120c.

[0040] In this cam clutch 100c, when the transmitted torque reaches a predetermined torque, the inclination limiting portions 133c of the cams 130c come into contact with the limiting members 160c. This prevents further inclination of the cams 130c to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between a cam receiving surface of the inner ring 110c and cam surfaces of the cams 130c or between a cam receiving surface of the outer ring 120c and cam surfaces of the cams 130c, and the torque is released. Fourth embodiment

[0041] As in Fig. 13, a cam clutch 100d according to a fourth embodiment of the present invention includes an inner ring 110d and an outer ring 120d coaxial with each other and rotatable relative to each other, a plurality of cams 130d circumferentially disposed between the inner ring 110d and the outer ring 120d to transmit torque, and biasing means (coil spring) 150d for biasing the plurality of cams 130d in the radial direction.

[0042] The plurality of cams 130d in the present embodiment each have a continuous circumferential surface different from the cam surfaces and can be self-aligned without using a cage member, but a cage member may also be provided.

[0043] Inclination limiting portions 133d are provided in two side regions of each cam 130d and limit the inclination in an engagement direction by coming into contact with limiting members 160d forming locking portions.

[0044] The limiting elements 160d are ring-shaped and pressed into the inside of two side regions of the outer ring 120d.

[0045] In this cam clutch 100d, when the transmitted torque reaches a predetermined torque, the inclination limiting portions 133d of the cams 130d come into contact with the limiting members 160d. This prevents further inclination of the cams 130d to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between a cam receiving surface of the inner ring 110d and cam surfaces of the cams 130d or between a cam receiving surface of the outer ring 120d and cam surfaces of the cams 130d, and the torque is released. Fifth embodiment

[0046] As in the Fig. 14 and Fig. 15, a cam clutch 100 according to a fifth embodiment of the present invention includes an inner ring 110e and an outer ring 120e coaxial with each other and rotatable relative to each other, a plurality of cams 130e circumferentially arranged between the inner ring 110e and the outer ring 120e to transmit torque, and biasing means (coil spring) 150e for biasing the plurality of cams 130e in the radial direction.

[0047] The plurality of cams 130e in the present embodiment each have a continuous circumferential surface different from the cam surfaces and can be self-aligned without using a cage member, but a cage member may also be provided.

[0048] An inclination limiting portion 133e is provided in a side region of each cam 130e and limits the inclination in an engagement direction by coming into contact with a locking portion 121e provided in the outer ring 120e.

[0049] In this cam clutch 100e, when the transmitted torque reaches a predetermined torque, the inclination limiting portions 133e of the cams 130e come into contact with the locking portion 121e of the outer ring 120e. This prevents further inclination of the cams 130e to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between a cam receiving surface of the inner ring 110e and cam surfaces of the cams 130e, or between a cam receiving surface of the outer ring 120e and cam surfaces of the cams 130e, and the torque is released. Sixth embodiment

[0050] As in Fig. 16, a cam clutch 100f according to a sixth embodiment of the present invention includes an inner ring 110f and an outer ring 120f coaxial with each other and rotatable relative to each other, a plurality of cams 130f circumferentially disposed between the inner ring 110f and the outer ring 120f to transmit torque, and biasing means (coil spring) 150f for biasing the plurality of cams 130f in the radial direction.

[0051] The plurality of cams 130f in the present embodiment each have a continuous circumferential surface different from the cam surfaces and can be self-aligned without using a cage member, but a cage member may also be provided.

[0052] An inclination limiting portion 133f is provided in a side region of each cam 130f and limits the inclination in an engagement direction by coming into contact with a limiting member 160f forming a locking portion.

[0053] The limiting elements 160f are ring-shaped and inserted into the inside of a side region of the outer ring 120f.

[0054] The other side areas of the cams 130f are preloaded by the preloading devices (tube spring) 150f.

[0055] In this cam clutch 100f, when the transmitted torque reaches a predetermined torque, the inclination limiting portions 133f of the cams 130f come into contact with the limiting member 160f constituting the locking portion. This prevents further inclination of the cams 130f to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between a cam receiving surface of the inner ring 110f and cam surfaces of the cams 130f, or between a cam receiving surface of the outer ring 120f and cam surfaces of the cams 130f, and the torque is released. Seventh embodiment

[0056] As in the Fig. 17 to 20, a cam clutch 100g according to a seventh embodiment of the present invention includes an inner ring 110g and an outer ring 120g coaxial with each other and rotatable relative to each other, a plurality of cams 130g circumferentially disposed between the inner ring 110g and the outer ring 120g to transmit torque, and biasing means (coil spring) 150g for biasing the plurality of cams 130g in the radial direction.

[0057] The plurality of cams 130g in the present embodiment each have a continuous circumferential surface different from the cam surfaces and can be self-aligned without using a cage member, but a cage member may also be provided.

[0058] An inclination limiting portion 133g is provided in a side region of each cam 130g and limits the inclination in an engagement direction by coming into contact with a locking portion 111g provided in the inner ring 110g.

[0059] In this cam clutch 100g, when the transmitted torque reaches a predetermined torque, the inclination limiting portions 133g of the cams 130g come into contact with the locking portion 111g. This prevents further inclination of the cams 130g to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between a cam receiving surface of the inner ring 110g and cam surfaces of the cams 130g or between a cam receiving surface of the outer ring 120g and cam surfaces of the cams 130g, and the torque is released. Eighth embodiment

[0060] As in the Fig. 21 to 23, a cam clutch 100h according to an eighth embodiment of the present invention includes an inner ring 110h and an outer ring 120h coaxial with each other and rotatable relative to each other, a plurality of cams 130h circumferentially disposed between the inner ring 110h and the outer ring 120h to transmit torque, and biasing means (coil spring) 150h for biasing the plurality of cams 130h in the radial direction.

[0061] The plurality of cams 130h are supported and aligned in the circumferential direction by a cage part 140h.

[0062] Each cam 130h has an inclination limiting portion 133h that limits the inclination in an engagement direction by coming into contact with a locking portion 141h of the cage member 140h.

[0063] In this cam clutch 100h, when the transmitted torque reaches a predetermined torque, the inclination limiting portions 133h of the cams 130h come into contact with the locking portions 141h of the cage member 140h. This prevents further inclination of the cams 130h to prevent further engagement. Accordingly, when a torque higher than the predetermined torque is applied, slippage occurs between a cam receiving surface of the inner ring 110h and cam surfaces of the cams 130h or between a cam receiving surface of the outer ring 120h and cam surfaces of the cams 130h, and the torque is released.

[0064] While embodiments of the present invention have been described in detail, the present invention is not limited to the foregoing embodiments, and various design changes may be made without departing from the present invention as defined by the claims.

[0065] For example, in each of the foregoing embodiments, it is possible to use one of the following configurations: a configuration in which the inner ring is fixed and the outer ring is rotated; a configuration in which the outer ring is fixed and the inner ring is rotated; and a configuration in which both the inner ring and the outer ring are rotated. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-156432

[0004] JP 2005-505431 [0005, 0007]

Claims

[1] Cam clutch with a torque limiter function, which has: at least one pair of an inner ring and an outer ring which are coaxial with each other and rotatable relative to each other; a plurality of cams arranged in a circumferential direction between the inner ring and the outer ring; and Preloading means for preloading the plurality of cams so that they come into contact with the inner ring and the outer ring, wherein each of the cams has an inclination limiting portion that limits the inclination of the cam in an engagement direction by coming into contact with a locking portion provided in a portion of the cam clutch other than the cam receiving surfaces of the inner ring and the outer ring. [2] A cam clutch assembly with a torque limiter function according to claim 1, wherein the locking portion is provided in a cage member that supports and circumferentially aligns the plurality of cams. [3] Cam clutch unit with torque limiter function according to claim 1, in which the inclination limiting section is provided in one end region or two end regions of the cam in the axial direction, and the locking portion is provided directly or indirectly on the outer ring or the inner ring. [4] A cam clutch unit with a torque limiter function according to claim 2, wherein the locking portion is provided in a limiting member which is fitted to the outer ring or the inner ring from one side in the axial direction.

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