Cam clutch unit

Abstract

To provide a cam clutch unit that reduces the number of machining steps and level of difficulty of cam clutch production and reduces rotation resistance caused by rollers. The cam clutch unit includes: a plurality of cams and a plurality of rollers circumferentially arranged between an inner race and an outer race that are coaxial and rotatable relative to each other; a cage ring having a plurality of pocket portions that restrict circumferential relative movements of the cams and the rollers; and an annular spring that biases the cams. The cams each have, on one axial end face, an engagement step that can engage with the spring. The cage ring has a plurality of hook portions that restrict axial movements of the annular spring.

Claims

1. A cam clutch unit comprising: a plurality of cams and a plurality of rollers arranged between an inner race and an outer race that are coaxial and rotatable relative to each other; a cage ring having a plurality of pocket portions that restrict circumferential relative movements of the cams and the rollers; and an annular spring that biases the cams, the cam having, on one axial end face, an engagement step that can engage with the spring, the cage ring having a plurality of hook portions that restrict axial movements of the annular spring.

2. The cam clutch unit according to claim 1, wherein the hook portion has a hook bottom portion that restricts radial movements of the annular spring.

3. The cam clutch unit according to claim 1, wherein the pocket portions of the cage ring have surfaces circumferentially adjoining the rollers and shaped so as to restrict movements of the rollers toward the outer race and the inner race.

4. The cam clutch unit according to claim 1, wherein the cam has, on an end face opposite from the engagement step, a restriction step, and the pocket portion of the cage ring has, on a surface axially adjacent the restriction step of the cam, a restriction protrusion that restricts tilt of the cam.

5. The cam clutch unit according to claim 1, wherein the rollers each have a hollow shape.

6. The cam clutch unit according to claim 5, wherein the rollers each have a roller shaft axially longer than the rollers and loosely fitted in a hollow part of the roller.

7. The cam clutch unit according to claim 1, wherein the rollers each have an axial length not greater than an axial length of the cam not including the engagement step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of a cam clutch unit according to one embodiment of the present invention;

(2) FIG. 2 is a side view of the cam clutch unit shown in FIG. 1 viewed from the direction of the rotation axis;

(3) FIG. 3 is a side view and a front view of the cam in the cam clutch unit shown in FIG. 1;

(4) FIG. 4 is a side view and a front view of the roller in the cam clutch unit shown in FIG. 1;

(5) FIG. 5 is a partial side view and a cross-sectional view of the cam clutch unit shown in FIG. 1;

(6) FIG. 6 is a side view and a front view of the cam in a cam clutch unit according to another embodiment of the present invention;

(7) FIG. 7 is a partial side view and a cross-sectional view of the cage ring in the cam clutch unit according to another embodiment of the present invention;

(8) FIG. 8 is a partial side view of a variation example of the cage ring shown in FIG. 7;

(9) FIG. 9 is a partial side view of another variation example of the cage ring shown in FIG. 7;

(10) FIG. 10 is a schematic partially enlarged perspective view and a side view of a cam clutch unit according to yet another embodiment of the present invention;

(11) FIG. 11 is a perspective view of a conventional cam clutch unit;

(12) FIG. 12 is a side view of the cam clutch unit shown in FIG. 11 viewed from the direction of the rotation axis;

(13) FIG. 13 is a side view and a front view of the cam in the cam clutch unit shown in FIG. 11;

(14) FIG. 14 is a side view and a front view of the roller in the cam clutch unit shown in FIG. 11; and

(15) FIG. 15 is a partial side view and a cross-sectional view of the cam clutch unit shown in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(16) As shown in FIG. 1 to FIG. 5, the cam clutch unit 100 according to one embodiment of the present invention includes: a plurality of cams 130 provided as sprags for transmitting and interrupting torque between an inner race and an outer race, in an annular space between raceways of the inner race and outer race that are coaxial and rotatable relative to each other; a plurality of rollers 140 allowing the inner race and outer race to freely rotate; a cage ring 150 having a plurality of pocket portions 151 and 152 that restrict circumferential movements of the cams 130 and rollers 140 relative to each other, and an annular spring 160 biasing each of the plurality of cams 130 toward a direction in which the cams wedge against the inner race and outer race.

(17) Each of the plurality of cams 130 has an engagement step 131 that can engage with the annular spring 160 on one axial end face as shown in FIG. 3 and others.

(18) In this embodiment, the engagement step 131 is inclined, the right side in the drawings being on the radially outer side when the cam 130 is in a free state. The spring 160 pressing the right side of the engagement step 131 biases the cam 130 toward the inner race, as well as causes the cam 130 to rotate in an operating direction.

(19) The plurality of rollers 140 do not have any groove or step as shown in FIG. 4 and others. In this embodiment, the roller 140 has an axial length rw that is not greater than the axial length cw of the cam 130 not including the engagement step 131.

(20) In this embodiment, both end faces of the rollers 140 are chamfered along the outer peripheral edges to avoid catching the spring 160.

(21) The cage ring 150 includes a plurality of pocket portions 151 and 152 that respectively accommodate and restrict circumferential relative movements of the cams 130 and the rollers 140, and a plurality of hook portions 153 that restrict axial movements of the annular spring 160.

(22) In this embodiment, the pocket portions 151 and 152 of the cage ring 150 that respectively accommodate the cams 130 and the rollers 140 are circumferentially alternately disposed.

(23) The pocket portions 151 and 152 each restrict the movements of the cams 130 and rollers 140 toward one axial direction by an end face at one axial end, and the spring 160 restricts the movements of the cams and rollers toward the other axial direction.

(24) In this embodiment, the pocket portions 152 that accommodate the rollers 140 have surfaces adjoining the rollers 140 and shaped such as to restrict the movements of the rollers 140 toward the outer race and the inner race.

(25) The rollers 140 may have an axial length rw that is greater than the axial length cw of the cam 130 not including the engagement step 131. In this case, the pocket portions 151 and 152 of the cage ring 150 may be configured to allow the rollers 140 to protrude more than the cams 130 on the opposite side from the engagement steps 131 of the cams 130. This way, the cam clutch unit can tolerate a larger axial load, with the rollers 140 being free from the radial pressure exerted by the spring 160.

(26) Furthermore, in this embodiment, as shown in FIG. 5, the hook portions 153 adjacent on the left side of the pocket portions 151 accommodating the cams 130 each have a hook bottom portion 154 that restricts radial movement of the annular spring 160.

(27) This allows the spring 160 to press the right side of the engagement steps 131 of the cams 130 without the rollers 140 restraining the tension of the spring 160 at all. Each cam 130 is individually pressed by a midpoint of the span of the spring 160 tensioned between two hook bottom portions 154, so that they are capable of highly precise and uniform movements without being affected by posture changes of other cams 130.

(28) While this embodiment employs the same numbers of alternately arranged cams 130 and rollers 140, any numbers of cams 130 and rollers 140 may be used in any arrangement.

(29) The cams 130 may have any shape, such as a sprag shape, for example.

(30) Likewise, the hook bottom portions 154 may be arranged in any way in accordance with the respective numbers and arrangements of the cams 130 and rollers 140. The hook bottom portions 154 may have the same height in the radial direction, or may have different heights depending on their positions in the circumferential direction.

(31) Suitable arrangement and setting of the heights of the hook bottom portions 154 in accordance with the respective numbers and arrangements of the cams 130 and rollers 140 allows each cam to move uniformly and precisely as described in the embodiment above.

(32) In a cam clutch unit according to another embodiment of the present invention, the cams 130a include a restriction step 132 on the end face opposite from the engagement step 131a as shown in FIG. 6. The cage ring 150a has restriction protrusions 155 that restrict the tilt of the cams 130a on the surface of the pocket portions axially adjacent the restriction steps 132 of the cams 130a.

(33) The restriction protrusions 155 prevent the cams 130a from shifting and tilting on the opposite side from the engagement step 131a, as well as restrict the rotation range of the cams 130a, which prevents detachment of the cams and enhances the operation precision and speed of the cam clutch.

(34) The restriction protrusions may have any shape as long as they can prevent tilting of the cams and restrict cam rotation range. For example, as shown in FIG. 7, the entire outer peripheral side of the cage ring 150d may be axially protruded to form the restriction protrusions 155b. A crescent-shape restriction protrusion 155c shown in FIG. 8 would be able to define circumferential front and back limits and radial outer peripheral limit of the cage ring 150c. Restriction protrusions 155d may be disposed at three points in the circumferential front and back and near the radial outer peripheral edge as shown in FIG. 9.

(35) In a cam clutch unit according to yet another embodiment of the present invention, the rollers 140e are hollow and have a roller shaft 143 axially longer than the roller 140e loosely fitted in the hollow part 142 of the roller 140e, as shown in FIG. 10.

(36) The rollers 140e can thus be made more lightweight. The spring 160 restricting radial movements of the roller shafts 143 that do not rotate prevents radial detachment of the rollers 140e irrespective of the shape of the pockets.

(37) The spring 160 itself will suffer less wear, which can reduce adverse effects on the service life of the entire cam clutch.

(38) While one embodiment of the present invention has been described above in detail, the present invention is not limited to the above-described embodiment and may be carried out with various design changes without departing from the scope of the present invention set forth in the claims.

(39) For example, instead of providing the engagement step that can engage with the spring only on one end face at one axial end of the cams as in the embodiment described above, the engagement step may be provided on both axial end faces of the cams, with hook portions being provided also at both axial ends of the cage ring, for the cams to be biased by two annular springs.