Cam clutch unit

Abstract

A cam clutch unit (110) is provided with a plurality of cams (120) and a plurality of rollers (130), each roller (130) has a shaft part (131) extending in the axial direction and a pair of large-diameter parts (132) connected to both ends of the shaft part (131), a groove part (135) for mounting an annular spring (140) is formed by a space between the pair of large-diameter parts (132), and the outer peripheral surface of the shaft part (131) constituting the bottom surface (136) of the groove part (135) is formed by a curved surface. The spring (140) can make contact with the curved surface at the axial center position of the groove part (135), and the outer diameter of the curved surface monotonically increases from the axial center position to the large-diameter part (132) side.

Description

Technical Field

[0001] The present invention relates to a cam clutch unit for transmitting and cutting off torque between an input shaft and an output shaft. Background Art

[0002] As a cam clutch, it is known to include: a plurality of cams arranged between an inner ring and an outer ring that are arranged to be rotatable relative to each other on the same axis; a spacer ring having a plurality of notches that limit the relative movement of the cams in the circumferential direction; and an annular spring that applies force to the cams (see Patent Document 1, etc.).

[0003] In such a cam clutch, in order to ensure the coaxiality between the inner ring and the outer ring, it is conceivable to replace some of the multiple cams with freely rotatable rollers.

[0004] For example, Figure 16 As shown, the cam clutch unit 210 is configured such that a plurality of cams 220 and a plurality of rollers 230 are circumferentially arranged between an inner ring and an outer ring which are arranged to rotate relative to each other on the same axis, and the cams 220 and the rollers 230 are respectively housed in the cam recess 215 and the roller recess 216 of the spacer ring 211 to limit the circumferential relative movement of the cams 220 and the rollers 230.

[0005] The cam 220 and the roller 230 are configured to have circumferential grooves 221 and 235 , respectively. An annular spring 240 is housed in the grooves 221 and 235 to urge the cam 220 and the roller 230 toward the inner ring side.

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-106135 Summary of the Invention

[0008] Furthermore, the roller 230 constituting the cam clutch unit 210 is formed by cutting, for example. Figure 17 As shown, the outer peripheral surface of the shaft portion 231, which forms the bottom surface 236 of the groove portion 235, is flat when viewed from the side. The groove portion 235 is configured such that the axial dimension of the groove portion 235 is larger than the coil diameter of the spring 240 to facilitate smooth rotation of the roller 230, thereby forming a gap G between the spring 240 and the end surface of the large diameter portion 232 of the roller 230.

[0009] On such a roller 230, as Figure 18 As shown, roller 230 tends to tilt within notch 216 of spacer ring 211. The tilt of roller 230 increases friction torque, preventing smooth rolling of the inner and outer rings, or causes locking during idling.

[0010] In addition, since there is a gap G between the groove portion 235 and the spring 240, the roller 230 has room to move in the axial direction. Figure 19 As shown, as roller 230 moves in the axial direction, spring 240 also moves relatively close to the same direction as the movement of roller 230. If multiple rollers 230 move in opposite directions, spring 240 will form a sawtooth shape, and will not be able to exert the original force on cam 220. In particular, if the cam clutch unit is configured without a spacer ring, the axial offset of each roller will cause the width dimension of the cam clutch unit to become uneven.

[0011] Furthermore, there are problems such as the following: the selection of processing methods for forming the groove portion 235 is limited and the manufacturing cost is increased; and when the outer diameter of the shaft portion 231 constituting the groove portion 235 becomes a small diameter, insufficient strength is caused.

[0012] The present invention is based on the above situation and aims to provide a cam clutch unit that can reduce friction loss and lock suppression during idling while improving cam engagement and reducing width dimensional unevenness and processing costs.

[0013] The present invention is a cam clutch unit comprising: a plurality of cams and a plurality of rollers, which are arranged between an inner ring and an outer ring which are arranged to rotate relative to each other on the same axis; and an annular spring, which is installed in a groove portion formed on each of the cam and the roller, and applies force to the cam so that the cam contacts the inner ring and the outer ring. The problem can be solved by the following contents, namely, the roller has a shaft portion extending in the axial direction and a pair of large diameter portions connected to each end of the shaft portion, the groove portion is formed by a space between a pair of large diameter portions, so that the shaft portion contacts the spring and is subjected to force from the spring, the outer peripheral surface of the shaft portion constituting the bottom surface of the groove portion is contactable by the spring at the axial center position of the groove portion, and the outer diameter dimension increases monotonically from the axial center position toward the large diameter portion side.

[0014] According to the invention according to claim 1, the action of the groove bottom surface causes the spring to approach the groove's axial center axis, thereby correcting the roller's posture. This allows the roller to rotate smoothly on the respective rotational surfaces of the inner and outer rings. This prevents the roller from rocking about its radially extending axis or from moving axially, thereby reducing friction loss during idling and suppressing locking.

[0015] Furthermore, since the axial position of the roller groove portion can be kept consistent with the axial position of the cam groove portion, the spring can be prevented from changing shape, such as into a sawtooth shape. Thus, the cam can be urged with appropriate force, thereby improving meshing performance.

[0016] Furthermore, since the rollers themselves are dimensionally interchangeable with existing rollers, they can be directly adapted to the specifications of existing cam clutch units, regardless of the presence or absence of spacer rings, resulting in high versatility.

[0017] Furthermore, in a cam clutch unit that does not include a spacer ring, by preventing the axial movement of the roller, it is possible to reduce axial dimension variations and improve the degree of freedom in design.

[0018] According to the invention according to claim 2, since the roller grooves are formed by rolling, the fiber flow of the roller material is not interrupted, and the density is increased by compression, thereby achieving higher strength. Furthermore, since there is no need to discharge chips as in cutting, and processing can be performed with less power and in a shorter time, it is possible to achieve higher productivity while reducing manufacturing costs.

[0019] According to the invention according to claim 3 , the axial position of the groove portion of the roller and the axial position of the groove portion of the cam can be easily aligned, the meshing performance can be improved, and the axial dimension variation can be reduced.

[0020] According to the inventions of claims 4 to 7 , since the roller posture correction effect can be reliably obtained, the friction loss reduction effect and the lock suppression effect during idling can be reliably obtained, and the cam meshing performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a side view showing a configuration example of a cam clutch provided with a cam clutch unit according to the present invention, as seen from the axial direction.

[0022] Figure 2 It is a perspective view showing the structure of the cam clutch unit.

[0023] Figure 3 Yes Figure 2 FIG. 1 is a diagram showing a portion of a cross section of the cam clutch unit taken along a plane perpendicular to the rotation axis.

[0024] Figure 4 yes Figure 3 AA line section view in.

[0025] Figure 5 yes Figure 3BB line section view in.

[0026] Figure 6 It is a front view showing the structure of the spacer ring.

[0027] Figure 7 Yes Figure 2 A top view of a portion of the components of the cam clutch unit is shown.

[0028] Figure 8 This is a front view showing a configuration example of a roller.

[0029] Figure 9 Yes Figure 8 An enlarged view of a portion of the roller is shown.

[0030] Figure 10 This is a partially enlarged view showing the structure of another example of a roller.

[0031] Figure 11 This is a partially enlarged view showing the structure of still another example of a roller.

[0032] Figure 12 This is a partially enlarged view showing the structure of still another example of a roller.

[0033] Figure 13 It is a side view showing a configuration example of a cam clutch provided with a cam clutch unit according to another embodiment of the present invention, as seen from the axial direction.

[0034] Figure 14 yes Figure 13 The CC line section view in .

[0035] Figure 15 yes Figure 13 DD line section view in.

[0036] Figure 16 It is a perspective view showing a configuration example of a conventional cam clutch unit.

[0037] Figure 17 This is a front view showing an example of the structure of a roller.

[0038] Figure 18 It means in Figure 16 The cam clutch unit shown is a schematic diagram showing a state in which the rollers are oscillating about a shaft extending in the radial direction.

[0039] Figure 19 It means in Figure 16 A schematic diagram showing a state in which the rollers of the cam clutch unit shown are moving in the axial direction.

[0040] Explanation of symbols

[0041] 100 - cam clutch; 101 - inner ring; 102 - flange; 105 - outer ring; 110, 210 - cam clutch unit; 111, 211 - spacer ring; 112 - large diameter cylindrical portion; 113 - step portion; 114 - small diameter cylindrical portion; 115, 215 - notch portion for cam; 116, 216 - notch portion for roller; 117 - column portion; 120, 220 - cam; 121, 221 - groove portion; 130, 230 - roller; 131, 231 - shaft portion; 1 32, 232 - large diameter portion; 135, 235 - groove portion; 136, 236 - bottom surface; 137 - first circular arc; 138 - second circular arc; 140, 240 - spring; Cb - center of curvature of the bottom surface of the groove portion; Cs - center of the coil of the spring; Dc - coil diameter; La - axial center axis of the roller; Lr - axis of rotation of the roller; O - axis of rotation; R - radius of curvature; R1 - radius of curvature; R2 - radius of curvature; rc - radius of the coil of the spring; rs - radius of the shaft portion. DETAILED DESCRIPTION

[0042] like Figure 1 As shown, a cam clutch unit 110 according to an embodiment of the present invention is disposed between an inner ring 101 and an outer ring 105 that are coaxially rotatable relative to each other, and constitutes the cam clutch 100 . Figure 1 The symbol O is the axis of rotation.

[0043] like Figures 2 to 5 As shown, the cam clutch unit 110 includes: a spacer ring 111, which is arranged coaxially with the inner ring 101 and the outer ring 105; a plurality of cams 120 and a plurality of rollers 130, which are held by the spacer ring 111 and arranged in a circumferential direction; and an annular spring 140, which applies force to each of the plurality of cams 120 so as to make contact with the inner ring 101 and the outer ring 105, and at the same time, applies force to each of the plurality of rollers 130 so as to press them onto the inner ring 101.

[0044] like Figure 6 As shown, the spacer ring 111 in this embodiment is formed into a two-stage cylindrical shape, comprising a large diameter cylindrical portion 112 and a small diameter cylindrical portion 114, which is connected to one end of the large diameter cylindrical portion 112 in the axial direction via a step portion 113. The step portion 113 is located in the axial center.

[0045] On the spacer ring 111, there are formed a plurality of notch portions 115 for cams corresponding to each of the plurality of cams 120 and a plurality of notch portions 116 for rollers corresponding to each of the plurality of rollers 130 in a manner extending axially from the large-diameter cylindrical portion 112 to the small-diameter cylindrical portion 114 and radially from the outer peripheral side to the inner peripheral side.

[0046] The recessed portion 115 for the cam and the recessed portion 116 for the roller are formed to surround the cam 120 and the roller 130 on all sides when viewed from above in the radial direction, and are constructed to accommodate the cam 120 and the roller 130 in a state where one axial end portion of the cam 120 and the roller 130 protrudes radially outward from the outer peripheral surface of the small-diameter cylindrical portion 114.

[0047] In addition, the cam support surface of the column portion 117 that is formed in a manner extending in the axial direction and divides the recess portion 115 for the cam, and the roller support surface of the column portion 117 that is formed in a manner extending in the axial direction and divides the recess portion 116 for the roller are respectively formed in a shape that restricts the movement of the cam 120 and the roller 130 toward the inner ring side.

[0048] On the spacer ring 111 of this embodiment, recesses 116 for four rollers are formed in a manner that four rollers 130 are arranged at equal intervals in the circumferential direction, and recesses 115 for eight cams are formed in a manner that two cams 120 are arranged at equal intervals in the circumferential direction between adjacent rollers 130.

[0049] The cam clutch 100 includes rollers 130, which maintain the concentricity of the inner ring 101 and outer ring 105 and support radial loads without the use of other components such as bearings. The number of rollers 130 is not particularly limited, as long as there are at least three. Furthermore, the number and arrangement of cams 120 are not particularly limited and can be modified appropriately depending on the intended purpose.

[0050] The roller notch 116 is formed to hold the roller 130 in a state where both ends of the roller 130 protrude axially outward relative to both axial end surfaces of the cam 120 accommodated in the cam notch 115 .

[0051] Each of the plurality of cams 120 has a groove portion 121 at the center in the axial direction, in which the spring 140 can be accommodated and mounted.

[0052] In this embodiment, the bottom of the groove 121 is an inclined shape with a convex portion formed at an eccentric position, and is constructed so that the cam 120 is shaken in a direction of contact with the inner ring 101 and the outer ring 105 by pressing the convex portion at the bottom of the groove 121 with the spring 140.

[0053] like Figure 7 As shown, the axial dimension of the plurality of rollers 130 is configured to be larger than the axial dimension of the cam 120 , and a groove portion 135 capable of accommodating and mounting the spring 140 is provided at the center in the axial direction.

[0054] The spring 140 is composed of, for example, a hoop spring, is wound in the groove 121 of the cam 120 and the groove 135 of the roller 130, and is locked with the step 113 of the spacer ring 111 to restrict the cam 120 and the roller 130 from moving toward the outer ring.

[0055] Moreover, if Figure 8 As shown, the roller 130 in the cam clutch unit 110 is configured in a dumbbell shape, having a shaft portion 131 extending in the axial direction and a pair of large-diameter portions 132 connected to both ends of the shaft portion 131. A groove 135 is formed in the space between the pair of large-diameter portions 132 so that the shaft portion 131 contacts the spring 140 and is biased by the spring 140.

[0056] The roller 130 is formed by rolling, and the groove portion 135 is formed by a rolling groove formed so that the fiber flow of the material constituting the roller 130 extends continuously to the large diameter portion 132 .

[0057] Because the grooves 135 of roller 130 are formed by rolling, the fiber flow of the material forming roller 130 is not interrupted, and compression increases density, resulting in higher strength. Furthermore, since there is no need to discharge chips, unlike cutting, and processing can be performed in a shorter time with less power, higher productivity is achieved, and manufacturing costs can be reduced.

[0058] Also like Figure 9 As shown, the outer peripheral surface of the shaft portion 131 constituting the bottom surface 136 of the groove portion 135 is symmetrical with respect to the axial center axis La, and is formed by a curved surface in which the radius rs of the shaft portion 131 monotonically increases from the position of the center axis La toward the axial large diameter portion side.

[0059] In this embodiment, the cross-sectional shape of the bottom surface 136 of the groove portion 135 is a single arc shape with both ends smoothly connected to the end surface of the large diameter portion 132, and the curvature radius R of the bottom surface 136 is configured to be larger than the coil radius rc of the spring 140 (=Dc / 2, Dc is the coil diameter of the spring 140). Figure 9 , Lr is the rotation axis of the roller 130 , Cs is the coil center of the spring 140 , and Cb is the curvature center of the bottom surface 136 .

[0060] In addition, if Figure 7As shown, the curvature radius R of the bottom surface 136 of the groove portion 135 is set so that the axial length Sd between one end surface of the cam 120 and one end surface of the roller 130 when the cam 120 and the roller 130 are configured in a state where the axial center positions are consistent is larger than the gap G between the spring 140 and the groove portion 135 at the radial position where the coil center Cs of the spring 140 is located when the spring 140 is in contact with the bottom surface 136 of the groove portion 135 at the axial center position.

[0061] With this configuration, the axial position of the groove 135 of the roller 130 and the axial position of the groove 121 of the cam 120 can be easily aligned, thereby improving meshing performance and reducing axial dimension variations.

[0062] As described above, in the cam clutch unit 110, the bottom surface 136 of the groove 135 in the roller 130 has a single arc-shaped cross-section. Therefore, the action of the bottom surface 136 of the groove 135 causes the spring 140 to move toward the axial center axis of the groove 135, correcting the posture of the roller 130. This allows the roller 130 to rotate smoothly on the respective rotational surfaces of the inner ring 101 and the outer ring 105. This prevents the roller 130 from rocking about its radially extending axis or from moving axially, thereby reducing friction loss during idling and suppressing lockup.

[0063] Furthermore, since the axial position of the groove 135 of the roller 130 is maintained in alignment with the axial position of the groove 121 of the cam 120, the spring 140 can be prevented from changing in shape, such as into a sawtooth shape. This allows the cam 120 to be urged with an appropriate force, thereby improving meshing performance.

[0064] Furthermore, since the dimensions of the roller 130 itself are interchangeable with those of existing rollers, the roller 130 can be directly adapted to the specifications of existing cam clutch units, thereby achieving high versatility.

[0065] In the above, although the cross-sectional shape of the bottom surface 136 of the groove portion 135 on the roller 130 is constituted into a single arc shape smoothly connected to the end surface of the large diameter portion 132, the example is described. Figure 10As shown, the cross-sectional shape of the bottom surface 136 of the groove portion 135 in the roller 130 may be configured as a single arc with the center of curvature Cb located radially outward of the peripheral edge position on the end surface of the large diameter portion 132. In the groove portion 135 thus configured, the radius of curvature R of the bottom surface 136 is set such that, when the spring 140 is in contact with the bottom surface 136 of the groove portion 135 at the axial center, the radial position P2 of the intersection point of the bottom surface 136 and the end surface of the large diameter portion 132 is set radially inward relative to the radial position P1 of the coil center Cs of the spring 140.

[0066] In addition, the cross-sectional shape of the bottom surface 136 of the groove portion 135 on the roller 130 is not limited to a single arc shape, but can also be any shape selected from a compound arc shape, a quadratic curve shape, an involute curve shape, and a free curve shape, and can also be constructed as a curved surface shape having a curvature radius greater than the coil radius rc of the spring 140.

[0067] For example, in Figure 11 In the illustrated roller 130, the cross-sectional shape of the bottom surface 136 of the groove 135 is formed into a compound arc shape. This compound arc shape comprises a first arc 137 located axially in the center, and a second arc 138 connected to each end of the first arc 137 and having a different radius of curvature from the first arc 137. The radius of curvature R1 of the first arc 137 is set to be greater than the coil radius rc of the spring 140, while the radius of curvature R2 of the second arc 138 is set to be greater than the radius of curvature R1 of the first arc 137. In this example, the radius of curvature R1 of the first arc 137 is the same as the coil radius rc of the spring 140. Cb1 is the center of curvature of the first arc 137, and Cb2 is the center of curvature of the second arc 138.

[0068] In addition, Figure 12 In the roller 130 shown, the cross-sectional shape of the bottom surface 136 of the groove portion 135 is formed into a quadratic curve shape in which the curvature radius is smallest on the axial center axis La of the roller 130 and increases toward the axially larger diameter portion.

[0069] Although the cam clutch unit 110 according to the above embodiment is configured to include the spacer ring 111 , it may be configured not to include the spacer ring.

[0070] like Figures 13 to 15As shown in FIG, , a cam clutch unit 110 according to another embodiment of the present invention has the same configuration as the cam clutch unit 110 according to the above embodiment, except that it does not include a spacer ring. Specifically, the cam clutch unit 110 includes: a plurality of cams 120 and a plurality of rollers 130 disposed between an inner ring 101 and an outer ring 105, which are coaxially rotatable relative to each other; and an annular spring 140, mounted in grooves 121 and 135 formed in each of the cams 120 and rollers 130, to bias the cams 120 so that they contact the inner ring 101 and outer ring 105.

[0071] The inner ring 101 on the cam clutch 100 is constructed so that a flange portion 102 protruding radially outward extends along the entire circumference at one axial end portion, and a gear portion (not shown) is provided at the other axial end portion, thereby limiting the axial movement of the roller 130.

[0072] As described above, since the outer circumferential surface of shaft portion 131, which forms bottom surface 136 of groove 135 in roller 130, is formed as a curved surface whose outer diameter increases monotonically from the axial center position toward the larger diameter portion, the action of bottom surface 136 of groove 135 causes spring 140 to move toward the axial center axis of groove 135, thereby correcting the posture of roller 130. This maintains the axial position of groove 135 of roller 130 aligned with the axial position of groove 121 of cam 120, thereby suppressing changes in the shape of spring 140, such as serrations, and reducing axial dimensional variations.

[0073] Therefore, even with a configuration that does not include a spacer ring, it is possible to reduce friction loss and suppress locking during idling, and to improve the meshing performance of the cam 120 .

[0074] 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 changes can be made without departing from the scope of the present invention described in the claims.

Claims

1. A cam clutch unit comprising: a plurality of cams and a plurality of rollers disposed between an inner ring and an outer ring coaxially rotatable relative to each other; and an annular spring mounted in a groove formed in each of the cams and the rollers to bias the cams so as to bring the cams into contact with the inner ring and the outer ring, characterized in that: The roller has a shaft portion extending in the axial direction and a pair of large diameter portions connected to both ends of the shaft portion, and the groove portion is formed by the space between the pair of large diameter portions so that the shaft portion contacts the spring and receives the urging force from the spring. The outer peripheral surface of the shaft portion constituting the bottom surface of the groove portion is formed by a curved surface with which the spring can contact at the axial center position of the groove portion and whose outer diameter increases monotonically from the axial center position toward the large diameter portion.

2. The cam clutch unit according to claim 1, characterized in that The groove portion of the roller is composed of a roll-formed groove formed so that a fiber flow of a material constituting the roller continuously extends to the large-diameter portion.

3. The cam clutch unit according to claim 1, wherein: The roller is configured to have an axial dimension larger than that of the cam. When the cam and the roller are configured so that their axial center positions coincide with each other, the axial length between one end face of the cam and one end face of the roller is greater than the gap between the spring and the groove portion at the radial position of the center of the spring coil when the spring is in contact with the bottom surface of the groove portion at the axial center position.

4. The cam clutch unit according to claim 1, wherein: The cross-sectional shape of the bottom surface of the groove portion on the roller is any one of a single arc shape, a compound arc shape, a quadratic curve shape, an involute curve shape, and a free curve shape. The bottom surface of the groove portion includes a curved surface having a curvature radius equal to or greater than a coil radius of the spring.

5. The cam clutch unit according to claim 4, characterized in that The cross-sectional shape of the bottom surface of the groove portion on the roller is a single arc shape. The curvature radius of the bottom surface is larger than the coil radius of the spring.

6. The cam clutch unit according to claim 5, characterized in that The curvature radius of the bottom surface is a dimension such that, when the spring is in contact with the bottom surface of the groove portion at the axial center position, the radial position of the intersection of the bottom surface and the end surface of the large diameter portion is set to a dimension that is radially inward relative to the radial position of the center of the coil of the spring.

7. The cam clutch unit according to claim 4, characterized in that The cross-sectional shape of the bottom surface of the groove portion on the roller is a compound arc shape, and the compound arc shape includes: a first arc located in the axial center; and a second arc connected to both ends of the first arc, and having a curvature radius different from that of the first arc. The curvature radius of the first arc is equal to or greater than the coil radius of the spring, and the curvature radius of the second arc is larger than the curvature radius of the first arc.

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