Cam clutch

Abstract

To provide a cam clutch which has a simple structure, eliminates a need for high accuracy control, and needs a small driving force for changing an attitude of each cam forcibly to improve stability of clutch operation and attain high responsiveness.SOLUTION: A cam clutch includes multiple cams 140 supported between an inner ring 110 and an outer ring 120 by a cage member 150 and arranged in a circumferential direction. The cam clutch includes a selector 170 which may control a relative rotation angle formed between itself and the inner ring 110 or the outer ring 120, to which the cage member 150 is fixed, and has a cam attitude control surface 171 capable of contacting with a cam surface of each cam 140 and changing an attitude of the cam 140. The cam attitude control surface 171 has cam release parts each of which protrudes to the radial direction cam 140 side relative to a cam operation part and changes the attitude of the cam 140 to an inoperative attitude.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a cam clutch that is switchable between a free state that allows relative rotation between an outer ring and an inner ring, and a locked state that prohibits relative rotation between the outer ring and the inner ring. [Background technology]

[0002] As a clutch that controls the transmission and interruption of rotational force, a cam clutch is known that forcibly changes the position of a cam or sprag to switch between a locked state that prohibits relative rotational movement between the inner and outer rings (transmits rotational force) and a free state that allows relative rotational movement between the inner and outer rings (interrupts rotational force).

[0003] For example, Patent Document 1 discloses a device that has a cam posture changer equipped with multiple pin members as a means for forcibly tilting multiple cams arranged circumferentially between an inner ring and an outer ring, and the pin members move circumferentially relative to each other to press the side surfaces of the cams circumferentially, thereby forcibly changing the posture of the cams. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6882699 Summary of the Invention [Problem to be solved by the invention]

[0005] In these cam clutches, when switching from a locked state to a free state, if torque is being transmitted by the cam, a large driving force is required to change the position of the cam, and there is a risk that the switch will not be completed until torque transmission is completely eliminated. In addition, there is a risk of damaging the inner and outer ring raceway surfaces, and the mechanism and actuator for changing the cam position must be enlarged in accordance with the driving force.

[0006] The cam clutch known from Patent Document 1 is highly responsive and can secure the desired torque capacity, and since the pin member is positioned away from the pin tilting center, it is possible to generate a fairly large driving force to change the cam posture; however, it is necessary to secure the relative positions of each pin with high precision, and it is also necessary to control the rotation angle of the cam posture change part with high precision when changing the cam posture.

[0007] The present invention aims to solve these problems by providing a cam clutch with a simple configuration that does not require high-precision control, requires little driving force when forcibly changing the cam position, improves the stability of clutch operation, and provides high responsiveness. [Means for solving the problem]

[0008] The present invention solves the above problem by providing a cam clutch comprising an inner ring and an outer ring that are coaxially rotatable relative to each other, a plurality of cams that are arranged circumferentially between the inner ring and the outer ring, and a cage member that is fixed in a rotational direction to the inner ring or the outer ring and supports the plurality of cams, wherein the cage member is equipped with a selector having a cam attitude control surface that can control the rotation angle relative to the inner ring or the outer ring that is fixed in the rotational direction, and that comes into contact with the cam surface of the cam and can change the attitude of the cam, and the cam attitude control surface has a cam operating surface portion on which the cam operates normally, and a cam release surface that has a shape that protrudes radially toward the cam from the cam operating surface and changes the cam to a non-operating attitude. [Effects of the Invention]

[0009] According to the invention of claim 1, the cam attitude control surface can come into contact with the cam surface to change the attitude of the cam, and by having a cam operating portion and a cam releasing portion that protrudes radially toward the cam from the cam operating portion and changes the cam to an inoperative position, the operation of the cam can be released at any position of the cam releasing portion, so there is no need to align the positions of multiple cams with high precision, and there is also no need for high-precision control of the rotation angle of the selector. In addition, the driving force required to forcibly change the cam's position is small, so the parts and actuators used for switching can be made smaller and cheaper. This improves the stability of clutch operation, resulting in high responsiveness, and durability is improved by not damaging the inner and outer ring raceway surfaces. Furthermore, because switching occurs by riding over the end face of the cam, the selector's switching angle can be made large without requiring highly precise control, enabling reliable operation without being affected by dimensional tolerances or control errors.

[0010] According to the invention of claim 2, the cam surface that can come into contact with the cam attitude control surface of the selector is configured to be able to come into contact with the outer peripheral surface of the inner ring or the inner peripheral surface of the outer ring at different positions in the rotational axis direction of the cam surface, thereby reducing the transmission torque applied to the selector in the locked state, simplifying the structure of the selector, and further improving durability. According to the invention of claim 3, multiple sets of inner rings, outer rings, multiple cams and cage members are arranged in the direction of the rotation axis on either side of the selector, and the selector has cam attitude control surfaces for the cams on both sides of the rotation axis, so that by driving one selector, the operation of the cam clutches on both sides can be controlled at its rotational position, making it possible to switch between multiple states with a simple configuration.

[0011] According to the invention of claim 4, a spacing member is arranged between the inner and outer rings to maintain the gap between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring.The concentricity maintaining function provided by the spacing member makes it possible to omit other bearing members and make the system more compact in the axial direction.In addition, the axial centers of the inner and outer rings are aligned with high precision, reducing variation in the operation of multiple cams and further improving the stability of clutch operation. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view of a cam clutch according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the cam clutch shown in FIG. 1. [Figure 3] FIG. 2 is a cross-sectional view of the cam clutch shown in FIG. 1. [Figure 4] FIG. 6 is a cross-sectional view of a cam clutch according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a perspective view of a cam clutch according to a third embodiment of the present invention. [Figure 6] FIG. 6 is an exploded perspective view of the cam clutch shown in FIG. 5 . [Figure 7] FIG. 6 is a cross-sectional view of the cam clutch shown in FIG. 5 . [Figure 8] 10A and 10B are explanatory views of the operation of a cam clutch according to a third embodiment of the present invention. [Figure 9] 10A and 10B are explanatory views of the operation of a cam clutch according to a modified example of the third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Examples of the present invention will be described with reference to Figures 1 to 9. However, the present invention is not limited to these embodiments. [Example]

[0014] As shown in Figures 1 to 3, the cam clutch 100 according to the first embodiment of the present invention comprises an inner ring 110 and an outer ring 120 that are arranged on the same axis and are capable of relative rotation, a plurality of cams 140 that transmit and block power between the inner ring 110 and the outer ring 120, a cage member 150 that is fixed in the rotational direction to the outer ring 120 and supports the plurality of cams 140, and a selector 170 that has a cam attitude control surface 171 that can control the rotation angle relative to the outer ring 120, comes into contact with the cam surface of the cam 140, and can change the attitude of the cam 140. Furthermore, between the inner ring 110 and the outer ring 120, there are provided a plurality of rollers 149 which are arranged to roll on the outer peripheral surface of the inner ring 110 and the inner peripheral surface of the outer ring 120 as spacing members, and the plurality of cams 140 and the plurality of rollers 149 are supported by a cage member 150 at predetermined intervals in the circumferential direction on the same circumference. The spacing member may be a block member arranged to slide against the outer peripheral surface of the inner ring 110 and the inner peripheral surface of the outer ring 120, or the spacing member may be fixed to the cage member 150 or formed integrally with the cage member 150.

[0015] The cam attitude control surface 171 has a cam operating portion 172 that allows the cam 140 to operate normally, and a cam release portion 173 that protrudes radially toward the cam 140 from the cam operating portion 172 and changes the cam 140 to an inoperative attitude. In this embodiment, the cam surface of the cam 140 on the outer ring 120 side is configured so that most of the rotational axis direction contacts the inner surface of the outer ring 120, and part of the rotational axis direction contacts the cam attitude control surface 171 of the selector 170. The selector 170 is rotationally driven by an actuator 180, and is configured so that the rotation angle relative to the outer ring 120 can be controlled.

[0016] In this cam clutch 100 , the cage member 150 is fixed to the outer ring 120 . The cam 140 is arranged so that the entire inner cam surface faces the outer circumferential surface of the inner ring 110, a portion of the outer cam surface faces the cam attitude control surface 171 of the selector 170, and the majority of the outer cam surface faces the inner circumferential surface of the outer ring 120. An actuator 180 that rotates the outer ring 120 and the selector 170 is fixed to a fixed portion (not shown), and thereby the relative rotation angle between the outer ring 120 and the selector 170 is controlled by the actuator 180 .

[0017] The cam clutch 100 of this embodiment switches between a free state in which relative rotational movement of the inner ring 110 and the outer ring 120 is permitted and a locked state in which relative rotational movement of the inner ring 110 and the outer ring 120 is prohibited, depending on the rotation angle of the selector 170. The cam attitude control surface 171 of the selector 170 has a cam operating portion 172, which is a surface that is flush with the inner surface of the outer ring 120 or located more outer than that, and a cam release portion 173, which is a surface that protrudes radially toward the cam from the cam operating portion 172 and is located more inner than the inner surface of the outer ring 120. When the cam surface on the outer periphery of the cam 140 is positioned opposite the cam operating portion 172, the cam 140 operates as a normal cam clutch between the outer periphery of the inner ring 110 and the inner periphery of the outer ring 120, forming a one-way clutch. When the cam surface on the outer periphery of cam 140 is positioned opposite cam release portion 173, cam 140 is fixed in a position where it does not mesh between the outer periphery of inner ring 110 and the inner periphery of outer ring 120, and inner ring 110 is in a free state where it is not restricted from rotating in either direction relative to outer ring 120. [Example]

[0018] As shown in FIG. 4, the cam clutch 100b according to the second embodiment of the present invention is configured such that the cam surface of the cam 140 on the outer ring 120b side is in contact with the cam attitude control surface 171b of the selector 170b over the entire rotational axis direction, but is not in contact with the inner peripheral surface of the outer ring 120b. The other configurations are the same as those in the first embodiment. In this embodiment, the entire cam surface of the cam 140 on the outer ring 120b side in the rotational axis direction comes into contact with the cam attitude control surface 171b of the selector 170b, so that the attitude of the cam 140 can be reliably changed when it is set to the free state. Furthermore, the cam attitude control surface 171b of the selector 170b becomes the torque transmission surface in the locked state, and when switching to the free state, the torque transmission surface itself is moved to change the cam attitude, so switching can be performed reliably even when torque is applied. [Example]

[0019] As shown in Figures 5 to 7, a cam clutch 100c according to a third embodiment of the present invention includes two sets of inner rings 110c1, 110c2 and outer rings 120c1, 120c2 that are arranged on the same axis and are rotatable relative to each other; a plurality of cams 140 that transmit and cut off power between the inner ring 110c1 and the outer ring 120c1 and between the inner ring 110c2 and the outer ring 120c2; a cage member 150c1 that is fixed to the outer ring 120c1 in the direction of rotation and supports the plurality of cams 140; a cage member 150c2 that is fixed to the outer ring 120c2 in the direction of rotation and supports the plurality of cams 140; and a selector 170c that is arranged between the outer ring 120c1 and the outer ring 120c2 and has cam attitude control surfaces 171c1, 171c2 that are in contact with the cam surfaces of the cam 140 and can change the attitude of the cam 140 and can control the rotation angle relative to the outer rings 120c1, 120c2. As in the first embodiment, a plurality of rollers serving as spacing members may be disposed between the inner ring 110c1 and the outer ring 120c1, and between the inner ring 110c2 and the outer ring 120c2.

[0020] The cam attitude control surfaces 171c1 and 171c2 each have a cam operating portion 172 that allows the cam 140 to operate normally, and a cam release portion 173 that protrudes radially toward the cam 140 from the cam operating portion 172 and changes the cam 140 to an inoperative position. In this embodiment, the cam surface on the inner ring 110c1 side of the cam 140 arranged between the inner ring 110c1 and the outer ring 120c1 is configured so that most of the rotational axis direction contacts the outer peripheral surface of the inner ring 110c1, and part of the rotational axis direction contacts the cam attitude control surface 171c1 of the selector 170c. The cam surface of the cam 140 disposed between the inner ring 110c2 and the outer ring 120c2 on the outer ring 120c2 side is configured so that, as in the first embodiment, most of the rotational axis direction contacts the inner peripheral surface of the outer ring 120c2, and part of the rotational axis direction contacts the cam attitude control surface 171c2 of the selector 170c. The selector 170c is rotationally driven by an actuator 180, and is configured so that the rotation angle relative to the outer rings 120c1 and 120c2 can be controlled.

[0021] In this cam clutch 100c, a cage member 150c1 is fixed to an outer ring 120c1, and a cage member 150c2 is fixed to an outer ring 120c2. The cam 140, which is arranged between the inner ring 110c1 and the outer ring 120c1, is arranged so that the entire outer cam surface faces the inner surface of the outer ring 120c1, a portion of the inner cam surface faces the cam attitude control surface 171c1 of the selector 170c1, and the majority of the inner cam surface faces the outer surface of the inner ring 110c1. The cam 140, which is arranged between the inner ring 110c2 and the outer ring 120c2, is arranged so that the entire inner cam surface faces the outer circumferential surface of the inner ring 110c2, a portion of the outer cam surface faces the cam attitude control surface 171c2 of the selector 170c, and the majority of the outer cam surface faces the inner circumferential surface of the outer ring 120c2. The cam 140 arranged between the inner ring 110c1 and the outer ring 120c1 and the cam 140 arranged between the inner ring 110c2 and the outer ring 120c2 are arranged so as to form one-way clutches that are locked when rotated in opposite directions. Actuator 180, which rotates outer rings 120c1 and 120c2 and selector 170c, is fixed to a fixed portion (not shown), whereby the relative rotation angle between outer rings 120c1 and 120c2 and selector 170c is controlled by actuator 180.

[0022] As shown in Figure 8, the cam clutch 100c of this embodiment is configured to be switched by actuator 180 between a bidirectional free state (a state in which selector 170c is in the neutral position (0°)) in which relative rotational movement between both inner wheel 110c1 and outer wheel 120c1 and inner wheel 110c2 and outer wheel 120c2 is permitted, a first locked state (a state in which selector 170c is rotated -3° from the neutral position) in which relative rotational movement between inner wheel 110c1 and outer wheel 120c1 is prohibited and relative rotational movement between inner wheel 110c2 and outer wheel 120c2 is permitted, and a second locked state (a state in which selector 170c is rotated 3° from the neutral position) in which relative rotational movement between inner wheel 110c2 and outer wheel 120c2 is prohibited and relative rotational movement between inner wheel 110c1 and outer wheel 120c1 is permitted. The cam attitude control surface 171c1 of the selector 170c has a cam operating portion 172c1, which is a surface that is flush with or located more inward than the outer peripheral surface of the inner ring 110c1, and a cam release portion 173c1, which is a surface that protrudes radially toward the cam from the cam operating portion 172c2 and is located more outward than the outer peripheral surface of the inner ring 110c1. When the inner cam surface of the cam 140 is positioned opposite the cam operating portion 172c1, the cam 140 operates as a normal cam clutch between the outer circumferential surface of the inner ring 110c1 and the inner circumferential surface of the outer ring 120c1, forming a one-way clutch. When the inner cam surface of cam 140 is positioned opposite cam release portion 173c1, cam 140 is fixed in a position where it does not mesh between the outer circumferential surface of inner ring 110c1 and the inner circumferential surface of outer ring 120c1, and inner ring 110c1 is in a free state where it is not restricted from rotating in either direction relative to outer ring 120c1.

[0023] The cam attitude control surface 171c2 of the selector 170c has a cam operating portion 172c2, which is a surface that is flush with the inner surface of the outer ring 120c2 or located more outer than that, and a cam release portion 173c2, which is a surface that protrudes radially toward the cam from the cam operating portion 172c2 and is located more inner than the inner surface of the outer ring 120c2. When the cam surface on the outer periphery of the cam 140 is positioned opposite the cam operating portion 172c2, the cam 140 operates as a normal cam clutch between the outer periphery of the inner ring 110c2 and the inner periphery of the outer ring 120c2, forming a one-way clutch. When the cam surface on the outer periphery of cam 140 is positioned opposite cam release portion 173c2, cam 140 is fixed in a position where it does not mesh between the outer periphery of inner ring 110c2 and the inner periphery of outer ring 120c2, and inner ring 110c2 is in a free state where it is not restricted from rotating in either direction relative to outer ring 120c2.

[0024] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design modifications can be made without departing from the present invention as set forth in the claims. In each of the above embodiments, the illustrated actuator 180 is assumed to be a motor with a worm gear that meshes with the outer periphery of the selectors 170, 170b, 170c, but it may be any motor that rotates the selectors 170, 170b, 170c relative to the outer rings 120, 120b, 120c1, 120c2. Furthermore, as a modified example of the third embodiment, as shown in FIG. 9, the selector 170d may have both cam attitude control surfaces 171d1 and 171d2 that can change the attitude of the cam 140 provided on the outer rings 120d1 and 120d2, and further, both cam attitude control surfaces may be provided on the inner ring side. [Explanation of symbols]

[0025] 100 ··· Cam clutch 110 ··· Inner circle 120 Outer ring 140 Cam 149 ··· Laura 150 Cage member 170 ··· Selector 171 ··· Cam attitude control surface 172 Cam operating part 173 Cam release part 180 ··· Actuator

Claims

1. A cam clutch comprising an inner ring and an outer ring that are coaxially arranged so as to be rotatable relative to each other, a plurality of cams that are arranged in the circumferential direction between the inner ring and the outer ring, and a cage member that is fixed to the inner ring or the outer ring in the rotational direction and supports the plurality of cams, a selector having a cam attitude control surface that can control a rotation angle of the cage member relative to the inner ring or the outer ring fixed in a rotation direction, that comes into contact with a cam surface of the cam, and that can change the attitude of the cam; A cam clutch characterized in that the cam attitude control surface has a cam operating portion in which the cam operates normally, and a cam release portion that protrudes radially toward the cam from the cam operating portion and changes the cam to an inoperative attitude.

2. 2. A cam clutch according to claim 1, wherein the cam surface capable of contacting the cam attitude control surface of the selector is configured to be capable of contacting the outer peripheral surface of the inner ring or the inner peripheral surface of the outer ring at different positions in the rotational axis direction of the cam surface.

3. 3. The cam clutch according to claim 1, further comprising a spacing member disposed between the inner ring and the outer ring to maintain a gap between the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring.

4. a plurality of sets of the inner ring, the outer ring, the plurality of cams, and the cage member are provided in the rotation axis direction with the selector interposed therebetween; 4. A cam clutch according to claim 1, wherein the selector has cam attitude control surfaces for the cams on both sides in the direction of the rotation axis.

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