Cam clutch

Abstract

To provide a cam clutch which can stabilize biasing force applied to cams to achieve improvement of durability and stability of an operation.SOLUTION: Biasing means 150 which biases cams 130 so that the cams 130 contact with an inner ring 110 and an outer ring 120 is formed by a ribbon spring which is formed so that a base 151 having cam storage parts 152 and cam biasing parts 153 forms an annular shape. The ribbon spring has an end structure 155 configured to allow both ends of the base 151 to push each other in a circumferential direction. The end structure 155 is configured to include a contact portion 156 that is provided so as to extend in a radial direction and make surface-contact with any of the inner ring 110, the outer ring 120, and a cage ring 140 that holds the cams 130.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a cam clutch equipped with a ribbon spring. [Background technology]

[0002] A cam clutch primarily comprises multiple cams arranged between an inner ring and an outer ring, a retainer that holds the multiple cams, and a biasing means that biases each cam in the direction of meshing with the inner ring and the outer ring. The cams are engaged and disengaged with the inner ring and the outer ring in response to the relative movement of the inner ring and the outer ring, thereby transmitting and blocking torque from the driving side to the driven side.

[0003] For example, Patent Document 1 discloses a sprag-type one-way clutch using an annular ribbon spring as a biasing means. This ribbon spring is formed into a ring shape by rolling a longitudinal member having a plurality of sprag receiving holes and tongue portions for biasing the sprags along the longitudinal direction. The sprag receiving holes located closest to one end in the longitudinal direction are overlapped with the sprag receiving holes facing the other longitudinal end edge, and the other longitudinal end located on the outer diameter side is adapted to abut against the cage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-152138 A Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, in order to bias each of the multiple cams with an appropriate biasing force, it is desirable for the ribbon spring to maintain a shape that is a perfect circle. However, in the ribbon spring having the above-mentioned configuration, the shape is maintained by abutting the other end edge of the longitudinal direction, which is located on the outer diameter side, against the cage, so that the spring becomes linear and the circumferential length of the ribbon spring may change. As a result, the tongue portions may not be able to abut at appropriate positions against all sprags, and some sprags may not be biased by the tongue portions. In particular, the biasing force applied to the sprags held in the sprag receiving holes closest to one end and the other end of the longitudinal member tends to become unstable, and these sprags do not contribute to the meshing of the inner and outer rings. One possible solution to this problem is to lengthen the tongue portion so that the sprags can be biased with an appropriate biasing force. However, as the tongue portion is made longer, stress increases and durability decreases. Furthermore, when a ribbon spring having the above-mentioned configuration is used in a selectable clutch that can switch between operating modes, the load on the cam is likely to vary, which can lead to problems such as a high switching thrust required to switch between operating modes, or the cam becoming stuck depending on where the tongue hits, making it impossible to switch between operating modes at all.

[0006] The present invention has been made based on the above circumstances, and has an object to provide a cam clutch that can stabilize the biasing force on the cam, thereby improving durability and operational stability. [Means for solving the problem]

[0007] The present invention solves the above problem by providing a cam clutch comprising an inner ring and an outer ring arranged coaxially and rotatably relative to each other, a plurality of cams arranged between the inner ring and the outer ring, a cage ring that holds the cams in a circumferential direction, and a biasing means that biases the cams into contact with the inner ring and the outer ring, wherein the biasing means is constituted by a ribbon spring having a base formed into a ring shape and having a cam accommodating portion and a cam biasing portion that biases the cam accommodated in the cam accommodating portion, and the biasing means has an end structure configured to enable ends of the base to press against each other in the circumferential direction, and the end structure is configured to include an abutment portion formed to extend radially and coming into face-to-face contact with any of the inner ring, the outer ring, and the cage ring. Effect of the Invention

[0008] According to the invention of claim 1, the elastic deformation of the biasing means in the circumferential and radial directions can be suppressed to maintain the desired shape, so that it is possible to prevent the positional deviation of the abutment position of the cam biasing part against the cam and the variation in the biasing force against the cam from occurring. Therefore, it is possible to bias all the cams with an appropriate biasing force, and the stability of the operation of the cam clutch can be improved. Furthermore, there is no need to increase the length or thickness of the cam biasing parts that bias the cams held by the cam holding part closest to one end of the base body and the cam holding part closest to the other end of the base body in order to increase the spring load, etc. This makes it possible to improve the durability of the biasing means and extend its lifespan, and also to manufacture the desired biasing means at a cost advantageous level. Furthermore, when the cam clutch is configured as a selectable clutch, the switching thrust required for switching the operating mode can be reduced, making it possible to reduce the size and cost of the switching force. Moreover, since it is possible to bias all cams so that their positions are uniform, it becomes easier to design applications such as selectable clutches that require cam position control.

[0009] According to the invention of claim 2, by forming a bent portion to increase the rigidity of the portion, the portion being aligned axially with the cam biasing portion, it is possible to more reliably prevent the misalignment of the contact position of the cam biasing portion with respect to the cam and the variation in the biasing force applied to the cam. According to the invention as defined in claim 3, by forming the bent portion so as to be able to come into contact with any one of the inner ring, the outer ring, and the cage ring, it is possible to ensure even higher shape stability for the biasing means.

[0010] According to the invention as defined in claims 4 to 6, an end structure can be formed that can bias all cams with an appropriate biasing force, thereby ensuring the attainment of the desired effects. In particular, in the end structure according to claim 5, there is no need to bend either end of the base body, and the desired end structure can be achieved by punching alone, making it easy to manufacture and eliminating the problem of uncertainty in accuracy due to bending. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a configuration of a cam clutch according to an embodiment of the present invention, with a part cut away; [Diagram 2] 2 is a cross-sectional view perpendicular to the rotation axis showing the configuration of the cam clutch shown in FIG. 1. [Diagram 3] FIG. 4 is a perspective view showing a configuration of a biasing means. [Figure 4] 11 is a cross-sectional view showing a schematic state in which a cam biasing portion and a cam are in contact with each other; FIG. [Diagram 5] FIG. 4 is a perspective view showing an end structure of a biasing means. [Figure 6] 13A and 13B are schematic diagrams for explaining the action and effect of the end structure of the biasing means. [Figure 7] 13 is a diagram showing an end structure of a biasing means in a cam clutch according to another embodiment of the present invention. FIG. [Figure 8] FIG. 8 is a plan view illustrating the end structure shown in FIG. 7. [Figure 9]13 is a diagram showing an end structure of a biasing means in a cam clutch according to still another embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] 1 and 2, a cam clutch 100 according to the present invention includes an inner ring 110 and an outer ring 120 that are coaxially rotatable relative to each other, a plurality of cams 130 that are arranged at intervals in the circumferential direction in the annular space between the inner ring 110 and the outer ring 120, a cage ring 140 that is coaxially rotatable together with the outer ring 120 between the inner ring 110 and the outer ring 120 and holds each of the plurality of cams 130, and biasing means 150 that biases each of the plurality of cams 130 in the meshing direction so as to contact the inner ring 110 and the outer ring 120. C in FIGS. 1 and 2 is the rotation axis.

[0014] The cam 130 has a constricted portion 131 in the radial center and is configured to have a generally gourd-like shape (see FIG. 4). In this embodiment, the cam 130 is configured to mesh with the inner ring 110 and the outer ring 120 when the inner ring 110 is rotated in the forward direction (clockwise in FIG. 2) or when the outer ring 120 is rotated in the reverse direction (counterclockwise in FIG. 2). In this embodiment, the multiple cams 130 are arranged, for example, at equal intervals in the circumferential direction, but the arrangement of the cams 130 is not particularly limited, and they do not have to be arranged at equal intervals in the circumferential direction.

[0015] The cage ring 140 includes a cylindrical main body portion 141 extending in the axial direction. Cam holders 142 are provided on the main body portion 141 so as to be aligned in the circumferential direction. In this embodiment, the cage ring 140 is provided rotatably together with the outer ring 120 so that the main body portion 141 is located on the radially outer ring side, and is configured to receive a head portion on the radially outer side relative to the constricted portion 131 of the cam 130 to hold the cam 130. The cage ring 140 may be provided so that the main body portion 141 is located on the radially inner ring side, and is configured to receive a leg portion on the radially inner side relative to the constricted portion 131 of the cam 130 to hold the cam 130.

[0016] The biasing means 150 is constituted by a ribbon spring, and in this embodiment, the biasing means 150 is disposed between the inner ring 110 and the cage ring 140 . The ribbon spring in this embodiment is formed in a ring shape from a thin metal band-like base body 151 having a cam accommodating portion 152 and a cam biasing portion 153 that biases the cam 130 housed in the cam accommodating portion 152, as shown in FIG. 3, for example. Cam accommodating portion 152 is configured by a hole having an opening shape of, for example, a rectangular shape. Cam urging portion 153 is formed such that a plate-shaped portion extending from one longitudinal end edge that defines cam accommodating portion 152 into cam accommodating portion 152 forms a leaf spring. The plate-shaped portions that configure cam accommodating portion 152 and cam urging portion 153 can be formed by, for example, punching, and cam urging portion 153 can be formed by bending the plate-shaped portion. As shown in FIG. 4, the cam biasing portion 153 is configured to abut against one side surface of the head portion of the cam 130 when the cam 130 is housed in the cam housing portion 152, and to bias the cam 130 in the meshing direction.

[0017] A bent portion 154 that protrudes radially outward is formed on each of the two side edges that define the cam accommodating portion 152 of the base body 151 so as to be aligned in the axial direction with the cam biasing portion 153. In this embodiment, the bent portion 154 is formed so as to be able to abut against the inner peripheral surface of the cage ring 140, for example. The bent portion 154 does not need to be formed so as to be able to abut against the inner peripheral surface of the cage ring 140, and may be formed so as to be convex inward in the radial direction. In addition, when the cage ring 140 is configured to receive the leg portion of the cam 130 and hold the cam 130, and the biasing means 150 is disposed between the outer ring 120 and the cage ring 140, the bent portion 154 may be formed so as to be convex inward in the radial direction and be able to abut against the outer peripheral surface of the cage ring 140, or may be formed so as to be convex outward in the radial direction and be able to abut against the inner peripheral surface of the outer ring 120.

[0018] Thus, the biasing means 150 in the cam clutch 100 configured as described above has an end structure 155 configured so that the ends of the base body 151 can press against each other in the circumferential direction. In this embodiment, as shown in FIG. 5, one end 151a and the other end 151b of the base 151 are formed so as to bend in the same radial direction and have an arc-shaped curved tip, and the ends of the base 151 are arranged so as to butt against each other in the circumferential direction, thereby forming an end structure 155 including an abutment portion 156 formed to extend radially and come into face-to-face contact with the cage ring 140.

[0019] 6, the biasing means 150 has such an end structure 155, and one end 151a and the other end 151b of the base 151 press against each other in the circumferential direction, suppressing the circumferential movement of the biasing means 150 relative to the cam 130, and the contact portion 156 comes into surface contact with the cage ring 140, thereby restricting the biasing means 150 in the radial direction. This makes it possible to suppress elastic deformation of the biasing means 150 in the circumferential and radial directions and to maintain the biasing means 150 in a desired shape, thereby preventing misalignment of the contact position of the cam biasing portion 153 relative to the cam 130 and variation in the biasing force relative to the cam 130. In particular, it is possible to reliably prevent the biasing force relative to the cam 130 housed in the cam housing portion 152 closest to one end of the base 151 and the cam housing portion 152 closest to the other end of the base 151 from becoming unstable. Therefore, according to the cam clutch 100 having the above configuration, it is possible to bias all of the cams 130 with an appropriate biasing force, and the stability of the operation of the cam clutch 100 can be improved.

[0020] In addition, since the shape stability of the biasing means 140 is improved and it is possible to bias all the cams 130 with an appropriate biasing force, it is not necessary to increase the spring load by increasing the length or thickness of a specific cam 130, for example, the cam biasing portion 153 for the cam 130 held in the cam accommodating portion 152 closest to one end of the base body 151 and the cam accommodating portion 152 closest to the other end of the base body 151. This makes it possible to improve the durability of the biasing means 140 and extend its life, and also makes it possible to manufacture the desired biasing means 140 cost-effectively.

[0021] In the cam clutch 100 of the present invention, the end structure 155 of the biasing means 140 is not limited to that in the above embodiment, and may be, for example, the structure shown in FIG. 7 or the structure shown in FIG.

[0022] The end structure 155 of the biasing means 150 shown in Figure 7 is formed by connecting one end 151a and the other end 151b of the base body 151 by an elastic body 160, and configuring the elastic body 160 so that it can abut against the outer peripheral surface of the main body portion 141 of the cage ring 140. To specifically explain the end structure 155 according to this embodiment, as shown in FIG. 8, the base 151 of the biasing means 150 is configured to be substantially ladder-shaped, and the engaging portions 157 extending outward in the length direction are formed in a comb-teeth shape at each of both ends in the length direction. The elastic body 160 is configured, for example, by a U-shaped leaf spring, and each of the movable pieces continuing to each of both ends of the curved portion is formed with a through hole into which the engaging portion 157 of the base 151 can be inserted. In this embodiment, the elastic body 160 is disposed in such a manner that the curved portion is convex toward the inside in the radial direction, and the curved portion abuts against the outer circumferential surface of the cage ring 140 to form the abutment portion 156. The tip side portions of each movable piece are bent so as to extend in a direction away from each other in the circumferential direction, and are fixed to the outer circumferential surface of the base 151. The engaging portion 157 on one end side of the base 151 and the engaging portion 157 on the other end side of the base 151 are configured to mesh with each other, and the elastic body 160 is configured to elastically deform so that the ends of the base 151 can press against each other in the circumferential direction. Even when using a biasing means 150 having such an end structure 155, it is possible to suppress elastic deformation of the biasing means 150 in the circumferential and radial directions and maintain the biasing means 150 in the intended shape, thereby making it possible to prevent misalignment of the abutment position of the cam biasing portion 153 against the cam 130 and variation in the biasing force against the cam 130.

[0023] In this embodiment, a configuration has been described in which the elastic body 160 is capable of abutting against the outer peripheral surface of the cage ring 140, but it may also be configured to be convex radially outward so as to be capable of abutting against the inner peripheral surface of the outer ring 120, for example.

[0024] 9 is configured by arranging one end 151a and the other end 151b of the base 151 so as to overlap in the radial direction. A bent portion 154 that is convex toward the inside in the radial direction is formed on one end side of the cam housing portion 152 closest to one end in the longitudinal direction of the base 151, and a contact portion 156 that is continuous with the bent portion 154 and contacts the cage ring 140 is formed. A cam pressing portion 158 that is configured to be able to contact the constricted portion 131 of the cam 130 is formed on the other end edge of the cam housing portion 152 closest to the other end in the longitudinal direction of the base 151, which is opposed in the circumferential direction to the one end edge in the longitudinal direction where the cam pressing portion 153 is formed. The tip portion of the cam pressing portion 158 is shaped to follow the constricted portion 131 of the cam 130 so as not to hinder the rotation of the cam 130. The other end in the longitudinal direction of the base body 151 is capable of abutting against a bent portion 154 formed on one end side in the longitudinal direction of the base body 151 . In the biasing means 150 having such an end structure 155, the abutment portion 156 abuts against the cage ring 140 located radially outward from the biasing means 150, and the cam pressing portion 158 abuts against the constricted portion 131 of the cam 130 located radially inward from the biasing means 150, thereby restricting the biasing means 150 in the radial direction. In addition, in the circumferential direction, the other end of the base body 151 abuts against the bent portion 154 on one end side of the base body 151, allowing the ends of the base body 151 to press against each other in the circumferential direction. At this time, the base body 151 moves in the circumferential direction while being restricted in the radial direction, so that the shape stability of the biasing means 150 is maintained. Therefore, even when using a biasing means 150 having such an end structure 155, it is possible to suppress elastic deformation of the biasing means 150 in the circumferential and radial directions and maintain the biasing means 150 in the intended shape, and it is possible to prevent misalignment of the abutment position of the cam biasing portion 153 with the cam 130 and variation in the biasing force with respect to the cam 130.

[0025] In addition, 170 in FIG. 9 denotes an operation mode switching means that is provided so as to be drivable independently of the rotational operation of the inner ring 110 and the outer ring 120. However, in a cam clutch that is not provided with an operation mode switching means, the biasing means 150 may be configured to have an end structure 155 as shown in FIG. 9.

[0026] 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. The present invention may be applied to a selectable clutch configured to be able to switch between operating modes. In such a case, it is possible to reduce the switching thrust required for switching between operating modes, making it possible to reduce the size and cost of the switching power. Moreover, since it is possible to bias all cams so that their positions are uniform, it becomes easier to design applications such as selectable clutches that require cam position control. [Explanation of symbols]

[0027] 100 ··· Cam clutch 110... Inner circle 120 Outer ring 130 Cam 131 ... Narrow part 140 ··· Cage ring 141 Main body 142 Cam holder 150 .... Biasing means 151 ... base 151a...One end 151b...Other end 152 Cam housing 153 Cam biasing portion 154 Bend 155... End structure 156... Contact part 157 ... Engagement portion 158 Cam holding part 160 Elastic body 170 Operation mode switching means C...Rotation axis center

Claims

1. A cam clutch comprising an inner ring and an outer ring arranged coaxially and relatively rotatably, a plurality of cams arranged between the inner ring and the outer ring, a cage ring that holds the cams in a circumferential direction, and a biasing means that biases the cams to contact the inner ring and the outer ring, the biasing means is constituted by a ribbon spring having a base body formed to form a ring, the base body having a cam housing portion and a cam biasing portion that biases the cam housed in the cam housing portion, the biasing means has an end structure configured to enable ends of the base body to press against each other in a circumferential direction, The cam clutch is characterized in that the end structure includes an abutment portion formed to extend radially and in surface contact with any one of the inner ring, the outer ring, and the cage ring.

2. 2. The cam clutch according to claim 1, wherein a bent portion that is convex radially outward or radially inward is formed on each of the two side edges that define the cam accommodating portion of the base body so as to be aligned in the axial direction with the cam biasing portion.

3. 3. The cam clutch according to claim 2, wherein the bent portion is formed so as to be able to come into contact with any one of the inner ring, the outer ring, and the cage ring.

4. Both ends of the base body in the longitudinal direction are bent in the same radial direction, and the tip is curved in an arc shape, 2. The cam clutch according to claim 1, wherein the abutting portion is formed by arranging ends of the base body so as to abut against each other in the circumferential direction.

5. 2. A cam clutch as claimed in claim 1, characterized in that the ends of the base body are connected to each other by an elastic body that is convex radially outward or radially inward, and the abutment portion is formed by the elastic body.

6. the biasing means is configured to form a ring by arranging ends of the base body so as to overlap each other in a radial direction, a bent portion that is convex toward the radially outward or radially inward direction is formed on one end side of the base body from a cam accommodating portion that is closest to one end of the base body in the longitudinal direction, and a contact portion that is continuous with the bent portion and contacts any one of the inner ring, the outer ring, and the cage ring is formed, 2. The cam clutch according to claim 1, wherein the other end in the longitudinal direction of the base body is configured to be able to abut on the bent portion.

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