Cam clutch

Abstract

The purpose of the present invention is to provide a cam clutch having a simple structure and capable of easily switching an operation mode with a small force.　The above problem is solved by the cam clutch being provided with: a first biasing means (150) that biases a plurality of cams (136), which are disposed between an inner ring (110) and an outer ring (120) disposed so as to be relatively rotatable coaxially with each other, so as to rotate in the meshing direction; and a second biasing means (155) that biases the plurality of cams (136) so as to rotate in the meshing release direction with a biasing force having a magnitude different from the biasing force exerted by the first biasing means (150), as well as being configured to enable the operation mode to be switched by a switching means (170) relatively reducing the biasing force exerted by one of the first biasing means (150) and the second biasing means (155), which has the larger biasing force on the same cam, compared to the biasing force exerted by the other biasing means.

Description

Cam clutch

[0001] The present invention relates to a cam clutch.

[0002] Some types of clutches that control the transmission and interruption of rotational force are configured with an inner ring and an outer ring, multiple cams as engaging elements arranged between the inner ring and the outer ring, and a biasing means that biases the cams in the direction of meshing.For example, some are also known that are configured with a switching means that is configured to change the operating mode of the clutch by forcibly tilting the cams.

[0003] For example, in Patent Documents 1 and 2, forward rotation sprags and reverse rotation sprags serving as engaging elements are arranged between an inner ring and an outer ring while being biased in the meshing direction by a biasing means, and the forward rotation sprags and reverse rotation sprags can be tilted in the disengagement direction by axially moving a switching means. In these two-way clutches, torque input to the inner ring or the outer ring causes one of the forward rotation sprags or reverse rotation sprags to act as a wedge and bite into the inner ring or the outer ring, thereby enabling torque transmission. Meanwhile, by axially moving the switching means, the forward rotation sprags and reverse rotation sprags can be tilted in the disengagement direction against the biasing force of the biasing means, allowing them to rotate freely in both forward and reverse directions. Furthermore, by providing a switching means, even one-way clutches can achieve a free mode that allows relative rotation of the inner ring and the outer ring in both forward and reverse directions.

[0004] Japanese Patent Laid-Open No. 6-017851 Japanese Patent Laid-Open No. 2008-121867

[0005] In a clutch equipped with a switching mechanism, the sprags are firmly supported by the torque received from the inner and outer rings during torque transmission. Therefore, an extremely large force is required for the switching mechanism to press the sprags circumferentially and tilt them in the disengagement direction, and operating the switching mechanism during torque transmission may result in damage to the sprags and / or the switching mechanism.

[0006] In particular, in a two-way clutch that can switch between driving and idling in both the forward and reverse directions, as torque is applied to the inner or outer ring, elastic deformation occurs in the sprags and the inner and outer rings, resulting in a rotational angle difference (windup) between the inner and outer rings. When the load is removed, the windup returns to zero. While one of the forward and reverse sprags engages with the inner and outer rings during torque transmission, the other sprag remains in sliding contact with the outer and inner rings, maintaining a state of engagement readiness. Therefore, when torque is released, one sprag tilts in the disengagement direction and transitions to an idling state. However, before one sprag is disengaged, the other sprag tilts in the engagement direction and begins to engage with the outer and inner rings, potentially resulting in a "meshing" in which all cams simultaneously engage. As described above, in the two-way clutch, even if the rotation of the inner or outer ring is stopped and torque is removed, the meshing caused by windup causes all of the sprags to mesh with high surface pressure, and therefore a large force is required to press the sprags circumferentially using the switching means and tilt them in the direction of disengagement.

[0007] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a cam clutch with a simple structure that allows the operation mode to be easily switched with a small force.

[0008] 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 first biasing means for biasing the cam to rotate in the meshing direction, and a switching means configured to forcibly rotate the cam and switch operating modes, wherein the clutch is provided with a second biasing means for biasing the cam to rotate in the meshing release direction with a biasing force of a magnitude different from the biasing force of the first biasing means, and the switching means has a cam attitude changing section configured to be able to change the biasing force of one of the first and second biasing means, which has a larger biasing force on the same cam, to be relatively smaller than the biasing force of the other biasing means.

[0009] According to the invention of claim 1, rather than directly pressing and tilting the cam, it is possible to switch between the locked mode and the free mode by changing the balance between the biasing force in the meshing direction by the first biasing means and the biasing force in the release direction by the second biasing means, both of which act on the same cam. Therefore, the force required to switch the operating mode need only be large enough to elastically deform the biasing means, making it possible to easily switch the operating mode with a simple structure and a small force. Furthermore, the switching means can be easily operated even during torque transmission without stopping the rotation of the inner and outer rings when switching the operating mode.

[0010] According to the invention of claim 2, there is no variation in the rotational movement of each of the multiple cams, thereby achieving stable operation. According to the invention of claim 3, by linking the rotational movements of the first cam and the second cam, which have different meshing directions, rotation of either the first cam or the second cam in the meshing direction can rotate the other cam in the disengagement direction, so that when one cam is meshed with the inner ring or outer ring, the other cam can be maintained separated from the inner ring or outer ring. This makes it possible to reliably prevent meshing.

[0011] According to the inventions of claims 4 to 6, by changing the biasing force of the first biasing means, the biasing force of the second biasing means causes the cam to rotate in the disengagement direction and move away from the inner or outer ring, making it possible to operate the switching means more easily with less force.

[0012] According to the invention of claim 7, at least one of the first and second biasing means is common to each of the multiple cams, which makes it possible to reduce the number of parts and avoid variations in the behavior of the cams.

[0013] According to the eighth aspect of the present invention, by selectively rotating either or both of the first cam and the second cam, it is possible to switch between four operation modes: a bidirectional lock mode in which torque can be transmitted in both the forward and reverse directions; a forward lock mode in which torque can be transmitted only in the forward direction; a reverse lock mode in which torque can be transmitted only in the reverse direction; and a bidirectional free mode in which the cam rotates freely in both the forward and reverse directions.

[0014] 1 is an exploded perspective view showing the configuration of a cam clutch according to a first embodiment of the present invention; FIG. 2 is a sectional perspective view cut along a plane including the rotation axis in an assembled state of the cam clutch shown in FIG. 1; FIG. 3 is an exploded perspective view showing the configuration of a cam mechanism; FIG. 4 is a plan view seen from one axial end side, showing the configuration of the cam clutch shown in FIG. 2 with some of the configuration omitted; FIG. 5 is a view showing the configuration of a cam, (a) a plan view seen from one axial end side, and (b) a side view; FIG. 6 is a side view showing a state in which the operation mode of the cam clutch shown in FIG. 1 has been switched from a bidirectional free mode to a bidirectional locked mode; FIG. 7 is a view schematically showing a state when the operation mode of the cam clutch shown in FIG. 1 is in a bidirectional free mode; FIG. 8 is a view schematically showing a state when the operation mode of the cam clutch shown in FIG. 1 is in a bidirectional locked mode; FIG. 9 is a view schematically showing a state when the inner ring is rotated in the forward direction when the operation mode of the dog clutch shown in FIG. 1 is in a bidirectional locked mode; FIG. 10 is a sectional perspective view showing the configuration of a cam mechanism in a cam clutch according to a second embodiment of the present invention, cut along a plane including the rotation axis; FIG. 11 is a schematic view showing the configuration of the cam clutch according to the second embodiment of the present invention with some of the configuration omitted, showing a plan view seen from one axial end side when the operation mode of the cam clutch is in a bidirectional locked mode. 13 is a plan view schematically showing a state when the operation mode of the cam clutch according to a second embodiment of the present invention is in a bidirectional free mode. FIG. 14 is a perspective view showing the configuration of a second biasing means in a cam clutch according to a third embodiment of the present invention, together with some cams. FIG. 15 is a schematic view showing the configuration of a cam clutch according to a third embodiment of the present invention, with some of the configuration omitted, and is a plan view seen from one axial end side when the operation mode of the cam clutch is in a bidirectional free mode. FIG. 16 is a perspective view showing a state when the operation mode of the cam clutch according to the third embodiment of the present invention is in a bidirectional lock mode, with some of the configuration of the cam clutch according to a fourth embodiment of the present invention, with a portion cut away. FIG. 17 is a side view showing a state when the operation mode of the cam clutch shown in FIG. 13 is in a bidirectional free mode. FIG. 18 is a plan view schematically showing a state when the operation mode of the cam clutch shown in FIG. 13 is in a bidirectional free mode. FIG. 19 is a side view showing a state when the operation mode of the cam clutch shown in FIG. 13 is in a forward direction lock mode.18 is a plan view schematically showing an engagement standby state when the operation mode of the cam clutch shown in FIG. 13 is in a forward direction lock mode. FIG. 19 is a side view showing a state when the operation mode of the cam clutch shown in FIG. 13 is in a reverse direction lock mode. FIG. 20 is a plan view schematically showing an engagement standby state when the operation mode of the cam clutch shown in FIG. 13 is in a reverse direction lock mode. FIG. 21 is a side view showing a state when the operation mode of the cam clutch shown in FIG. 13 is in a bidirectional lock mode. FIG. 22 is a perspective view showing a configuration of a cam clutch according to a fifth embodiment of the present invention, with a portion cut away. FIG. 22 is a diagram showing a part of a cross section taken on a plane including the rotation axis, showing a state when the operation mode of the cam clutch shown in FIG. 18 is in a lock mode in which torque can be transmitted in both directions between the outer ring and the first inner ring. FIG. 23 is a diagram showing a part of a cross section taken on a plane including the rotation axis, showing a state when the operation mode of the cam clutch shown in FIG. 18 is in a bidirectional free mode. FIG. 24 is a diagram showing a part of a cross section taken on a plane including the rotation axis, showing a state when the operation mode of the cam clutch shown in FIG. 18 is in a lock mode in which torque can be transmitted in both directions between the outer ring and the second inner ring. FIG. 10 is a plan view schematically showing yet another example of the configuration of the cam clutch according to the present invention, as viewed from one axial end side.

[0015] 1, a cam clutch 100 according to a first embodiment of the present invention includes an inner ring 110, an outer ring 120, a cam mechanism 130 that transmits and cuts off torque between the inner ring 110 and the outer ring 120, and a switching means 170 that is configured to be able to switch the operating mode of the cam clutch 100. As shown in FIG. 2, when the cam clutch 100 is assembled, the inner ring 110 and the outer ring 120 are arranged on the same rotation axis so as to be able to rotate relative to each other, and the cam mechanism 130 is arranged between the inner ring 110 and the outer ring 120.

[0016] As shown in FIG. 3, the cam mechanism 130 includes a plurality of cams 136, a cage ring 140 that holds each of the plurality of cams 136, a first biasing means 150 that biases each of the plurality of cams 136 to rotate in the meshing direction, and a second biasing means 155 that biases each of the plurality of cams 136 to rotate in the disengaging direction with a biasing force of a magnitude different from that of the first biasing means 150.

[0017] As shown in FIG. 4 , the multiple cams 136 include first cams 136 a and second cams 136 b that mesh with the inner ring 110 and the outer ring 120 in mutually different directions. In this embodiment, adjacent first cams 136 a and second cams 136 b form cam pairs 135, and multiple pairs are arranged on the same circumference at predetermined intervals in the circumferential direction. The arrangement of the first cams 136 a and second cams 136 b in the cam mechanism 130 is not particularly limited. However, by arranging the first cams 136 a and second cams 136 b alternately, the first cams 136 a and second cams 136 b can be rotated simultaneously by a common switching means, thereby preventing the structure of the cam clutch 100 from becoming complicated and large. Furthermore, the first cams 136 a and second cams 136 b do not need to be arranged alternately on the same circumference. The number of first cams 136 a and second cams 136 b may be the same or different.

[0018] The first cam 136a is configured to frictionally engage with the inner ring 110 and the outer ring 120 when the inner ring 110 is rotated in the forward direction (clockwise in FIG. 4) or the outer ring 120 is rotated in the reverse direction (counterclockwise in FIG. 4), and to incline in a direction to disengage from the inner ring 110 and become non-contact when the inner ring 110 is rotated in the reverse direction or the outer ring 120 is rotated in the forward direction. Therefore, the second cam 136b is configured to frictionally engage with the inner ring 110 and the outer ring 120 when the inner ring 110 is rotated in the reverse direction or the outer ring 120 is rotated in the forward direction, and to incline in a direction to disengage from the inner ring 110 and become non-contact when the inner ring 110 is rotated in the forward direction or the outer ring 120 is rotated in the reverse direction.

[0019] In this embodiment, the first cam 136a and the second cam 136b have, for example, the same outer shape, and the second cam 136b is the first cam 136a turned upside down. Hereinafter, the first cam 136a and the second cam 136b may be simply referred to as cam 136 unless they are particularly distinguished from each other. Note that the first cam 136a and the second cam 136b may have different outer shapes, but having the same outer shape makes it possible to reduce the number of parts.

[0020] 5(a) and 5(b), the cam 136 in this embodiment has a pivot shaft 137 provided on each of both end faces extending along a plane perpendicular to the rotation center so as to protrude axially outward. A notch 139a is formed in a side surface portion that continues to the inner ring-side engaging surface on the disengagement direction side (clockwise direction in FIG. 5(a)) of the contact point of the cam 136 with the inner ring 110. Furthermore, a step 139b is formed in a side surface portion that continues to the inner ring-side engaging surface on the engagement direction side (counterclockwise direction in FIG. 5(a)) of the contact point so as to be engageable with a connecting portion 156b of a torsion spring that constitutes second biasing means 155 (described later).

[0021] 3, the cage ring 140 is composed of a pair of annular plate-shaped members 141 and rod-shaped spacer members 145 that connect the annular plate-shaped members 141 at a predetermined interval in the axial direction. Each annular plate-shaped member 141 is formed with a retaining hole 142 that rotatably holds the rotation shaft portion 137 of the cam 136 and an insertion hole 143 through which the cam position changing portion 171 of the switching means 170 is inserted. The spacer members 145 are arranged on the same circumference at a predetermined interval in the circumferential direction so as to be positioned between the first cam 136a and the second cam 136b of each of the multiple cam pairs 135.

[0022] In this embodiment, the first biasing means 150 is made of a leaf spring and is provided corresponding to each cam 136. Specifically, as also shown in Fig. 5(a) , the first biasing means 150 is disposed in the notch 139a of the cam 136 with the bent portion positioned on the other axial end side, and one piece-like portion continuous with the bent portion is fixed to the cam 136 as a fixed piece. The other piece-like portion continuous with the bent portion is configured as a movable piece and is adapted to abut against a cam position changing portion 171 of the switching means 170.

[0023] The second biasing means 155 is formed of a torsion spring and provided corresponding to each cam 136. Specifically, as shown in FIG. 5( b), the torsion spring has two coil-shaped winding portions 156a and a connecting portion 156b extending linearly in the axial direction and connecting one end of each winding portion 156a. The winding portions 156a are fitted onto the rotary shaft portion 137 at one and the other axial ends of the cam 136, and the connecting portion 156b is engaged with a step portion 139b of the cam 136. The other end of each winding portion 156a is supported by a second biasing means support portion 144 formed on the annular plate-shaped member 141 of the cage ring 140, as shown in FIG. 4. This configuration makes it possible to avoid contact with the inner ring 110 when the cam 136 is lifted.

[0024] The switching means 170 is provided so as to be movable in the axial direction between a first fixed position and a second fixed position which is located axially closer to one end than the first fixed position. As shown in Figures 1 and 2, the switching means 170 is composed of a plurality of columnar cam position changing portions 171 which are disposed between the inner ring 110 and the outer ring 120 and formed to extend in the axial direction, and a pair of annular plate-shaped fixing members 175 which are fixed to both end faces of each cam position changing portion 171. The cam position changing portions 171 are disposed so as to be inserted into the insertion holes 143 of the cage ring 140 so as to be movable in the axial direction and to be positioned between adjacent cam pairs 135.

[0025] The cam posture change portion 171 is configured so that its cross-sectional shape changes in the axial direction, so that the biasing force exerted by one of the first biasing means 150 and the second biasing means 155, whichever has the greater biasing force on the same cam 136, can be changed so that it is relatively smaller than the biasing force exerted by the other biasing means.

[0026] In this embodiment, the cam position changing portion 171 is configured so that the biasing force of the first biasing portion 150 applied to the cam 136 can be changed by axial movement of the switching portion 170. Specifically, by axially moving the switching portion 170 from the first fixed position to the second fixed position at one axial end side, the first biasing portion 150 can be changed to a state in which it can bias the cam 136 with a biasing force greater than that of the second biasing portion 155; in other words, the biasing force of the second biasing portion 155 can be changed to be smaller than the biasing force of the first biasing portion 150. To specifically describe the configuration of the cam position changing portion 171, as shown in FIGS. 1 and 2 , the cam position changing portion 171 has a prismatic biasing force application portion 172, a biasing force change portion 173 continuous with one end of the biasing force application portion 172, and a prismatic biasing force release portion 174 continuous with one end of the biasing force change portion 173 and having a radial dimension smaller than that of the biasing force application portion 172. The biasing force changing portion 173 is formed so that the radially inner surface thereof extends at an inclination radially outward as it approaches one axial end.

[0027] The cam clutch 100 according to this embodiment includes a cam interlocking member 160 that transmits the rotation of one of the first cam 136 a and the second cam 136 b in the cam pair 135 to the other cam, thereby interlockingly rotating the first cam 136 a and the second cam 136 b. As shown in FIG. 3 , the cam interlocking member 160 includes an annular base portion 161 having the same outer diameter as the annular plate-shaped member 141 in the cage ring 140. One end surface of the base portion 161 is provided with circumferentially extending claw portions 162 that protrude axially and are spaced apart at predetermined intervals. As shown in FIG. 4 , the cam interlocking member 160 is fitted onto a spacer member 145 so that the claw portions 162 are positioned between adjacent cam pairs 135, restricting radial movement. The other end surface of the base portion 161 abuts against the inner surface of the annular plate-shaped member 141 in the cage ring 140.

[0028] In the above-described cam clutch 100, when the switching means 170 is in the first fixed position as shown by the dashed line in Fig. 6, the movable piece of the first biasing means 150 contacts the biasing force change portion 173 of the cam position change portion 171 as shown in Fig. 7, and the biasing force of the first biasing means 150 is smaller than the biasing force of the second biasing means 155, or the biasing force of the first biasing means 150 is released. As a result, both the first cam 136a and the second cam 136b are biased to rotate in the disengagement direction, and both the first cam 136a and the second cam 136b are spaced from the outer peripheral surface of the inner ring 110 and are in a non-contact state. Therefore, the operating mode of the cam clutch 100 is a bidirectional free mode that allows relative rotation of the inner ring 110 and the outer ring 120 in both the forward and reverse directions.

[0029] As shown by the solid line in FIG. 6 , when the switching means 170 is moved from the first fixed position to the second fixed position at one axial end, the cam position changing portion 171 presses the first biasing means 150 in the compression direction, as shown in FIG. 8A . As a result, the biasing force of the first biasing means 150 becomes greater than the biasing force of the second biasing means 155, and the first cam 136a and the second cam 136b are biased to rotate in the meshing direction. As a result, the first cam 136a and the second cam 136b come into sliding contact with the inner ring 110 and the outer ring 120, and either the first cam 136a or the second cam 136b enters an engagement standby state in which they can immediately engage with the inner ring 110 and the outer ring 120. Therefore, the operating mode of the cam clutch 100 is switched to a bidirectional lock mode in which relative rotation of the inner ring 110 and the outer ring 120 is prohibited in both the forward and reverse directions.

[0030] For example, as shown in FIG. 8B , when the inner ring 110 is rotated in the forward direction (clockwise in FIG. 8B ), the first cam 136a rotates in the meshing direction to frictionally engage with the inner ring 110 and the outer ring 120. The rotation of the first cam 136a presses the claws 162 of the cam interlocking member 160 in the circumferential direction, causing the cam interlocking member 160 to rotate. This causes the claws 162 of the cam interlocking member 160 to press the second cam 136b to rotate in the disengagement direction. The same occurs when the outer ring 120 is rotated in the reverse direction (counterclockwise in FIG. 8A ). On the other hand, when the inner ring 110 is rotated in the reverse direction or the outer ring 120 is rotated in the forward direction, the second cam 136b rotates in the meshing direction to frictionally engage with the inner ring 110 and the outer ring 120. Accordingly, the first cam 136a rotates in the disengagement direction due to the action of the cam interlocking member 160.

[0031] As described above, with the cam clutch 100, the operating mode can be switched between the bidirectional free mode and the bidirectional locked mode by changing the balance between the biasing force in the engagement direction by the first biasing means 150 and the biasing force in the disengagement direction by the second biasing means 155, which act on the same cam 136, rather than directly pressing and rotating the cam 136. Therefore, the force required to switch the operating mode need only be large enough to elastically deform the first biasing means 150, allowing for easy switching of the operating mode with a simple structure and a small force. Furthermore, the switching means 170 can be easily operated even during torque transmission without stopping the rotation of the inner ring 110 and the outer ring 120 when switching the operating mode. In particular, when switching from the two-way lock mode to the two-way free mode, the biasing force of the first biasing means 150 is reduced, and the biasing force of the second biasing means 155 causes the cam 136 to rotate in the disengagement direction and move away from the inner ring 110 or the outer ring 120, making it possible to operate the switching means 170 more easily with less force.

[0032] Furthermore, as one of the first cam 136a and the second cam 136b rotates in the meshing direction, the other cam can be rotated in the disengagement direction by the action of the cam interlocking member 160, so that when one cam is meshed with the inner ring 110 and the outer ring 120, the other cam can be maintained apart from the inner ring 110 or the outer ring 120. This makes it possible to reliably prevent jamming from occurring.

[0033] In the cam clutch 100 according to the first embodiment described above, the first biasing means 150 and the second biasing means 155 are provided for each of the plurality of cams 136. However, the first biasing means 150 may be any elastic body capable of biasing the first cam 136 a and the second cam 136 b to rotate in the meshing direction, and the second biasing means 155 may be any elastic body capable of biasing the first cam 136 a and the second cam 136 b to rotate in the disengagement direction. For example, at least one of the first biasing means 150 and the second biasing means 155 may be a common biasing means for the first cam 136 a and the second cam 136 b.

[0034] [Second embodiment] The cam clutch according to the second embodiment of the present invention has the same configuration as the cam clutch 100 according to the first embodiment, except that a garter spring common to the first cam 136 a and the second cam 136 b is used as the first biasing means 150 instead of the leaf spring in the cam clutch 100 according to the first embodiment.

[0035] As shown in FIG. 9, the garter spring as the first biasing means 150 is mounted in a mounting groove 138 formed to extend in the circumferential direction on the outer ring side engaging surface of each of the first cam 136a and the second cam 136b.

[0036] The cam position changer 171 of the switching means 170 in this embodiment is formed so that the radially outer surface of the biasing force changer 173 extends at an inclination radially inward toward one end (see FIG. 10B).

[0037] 10A , when the switching means 170 is in the first fixed position, the first biasing means 150 contacts the radially outer surface of the biasing force release portion 174 of the cam position changing portion 171, and the biasing force of the first biasing means 150 is greater than the biasing force of the second biasing means 155. As a result, both the first cam 136a and the second cam 136b are biased to rotate in the meshing direction, and both the first cam 136a and the second cam 136b are in sliding contact with the inner ring 110 and the outer ring 120, and either the first cam 136a or the second cam 136b is in a meshing standby state in which it can immediately engage with the inner ring 110 or the outer ring 120. Therefore, the operating mode of the cam clutch is a bidirectional lock mode in which relative rotation of the inner ring 110 and the outer ring 120 is prohibited in both the forward and reverse directions.

[0038] 10B , when the switching means 170 is moved from the first fixed position to the second fixed position at one axial end, the cam attitude changing portion 171 presses the first biasing means 150 in the radially expanding direction. As a result, the biasing force of the first biasing means 150 becomes smaller than the biasing force of the second biasing means 155, or the biasing force of the first biasing means 150 is released, and both the first cam 136a and the second cam 136b are biased to rotate in the disengagement direction. As a result, the first cam 136a and the second cam 136b are spaced from the outer peripheral surface of the inner ring 110 and are in a non-contact state. Therefore, the operating mode of the cam clutch 100 is switched to a bidirectional free mode that allows relative rotation of the inner ring 110 and the outer ring 120 in both the forward and reverse directions.

[0039] [Third Embodiment] The cam clutch according to the third embodiment of the present invention has the same configuration as the cam clutch 100 according to the first embodiment, except that a ribbon-shaped leaf spring common to the first cam 136 a and the second cam 136 b is used as the second biasing means 155 instead of the torsion spring in the cam clutch 100 according to the first embodiment.

[0040] 11 , the ribbon-shaped leaf spring serving as the second biasing means 155 includes a pair of annular portions 157 extending parallel to each other in the circumferential direction and a plurality of connecting portions 158 connecting the annular portions 157 in the axial direction at predetermined intervals, and is arranged so that the connecting portions 158 are positioned between the first cam 136 a and the second cam 136 b that constitute the cam pair 135. The connecting portions 158 include a first leaf spring portion 159 a that is formed so as to be convex outward in the radial direction and that biases the first cam 136 a to rotate in the disengagement direction, and a second leaf spring portion 159 b that is formed so as to be convex outward in the radial direction and that biases the second cam 136 b to rotate in the disengagement direction.

[0041] In the cam clutch according to the third embodiment, for example, when the switching means 170 is in the first fixed position, as shown in Fig. 12A, the movable piece of the first biasing means 150 contacts the biasing force change portion 173 of the cam position change portion 171, and the biasing force of the first biasing means 150 is smaller than the biasing force of the second biasing means 155, or the biasing force of the first biasing means 150 is released. As a result, both the first cam 136a and the second cam 136b are biased to rotate in the disengagement direction, and both the first cam 136a and the second cam 136b are spaced from the outer peripheral surface of the inner ring 110 and are in a non-contact state. Therefore, the operating mode of the cam clutch 100 is a bidirectional free mode that allows relative rotation of the inner ring 110 and the outer ring 120 in both forward and reverse directions.

[0042] 12B , when the switching means 170 is moved from the first fixed position to the second fixed position at one axial end, the cam position changing portion 171 presses the first biasing means 150 in the compression direction. As a result, the biasing force of the first biasing means 150 becomes larger than the biasing force of the second biasing means 155, i.e., the biasing force of the second biasing means 155 becomes smaller relative to the biasing force of the first biasing means 150, and the first cam 136a and the second cam 136b are biased to rotate in the meshing direction. As a result, the first cam 136a and the second cam 136b come into sliding contact with the inner ring 110 and the outer ring 120, and either the first cam 136a or the second cam 136b enters an meshing standby state in which they can immediately engage with the inner ring 110 and the outer ring 120. Therefore, the operation mode of the cam clutch 100 is switched to a bidirectional lock mode in which the relative rotational movement of the inner ring 110 and the outer ring 120 is prohibited in both the forward and reverse directions.

[0043] In the second and third embodiments described above, either the first urging means 150 or the second urging means 155 is configured as urging means common to each of the plurality of cams 136, but both the first urging means and the second urging means may be configured as urging means common to each of the plurality of cams 136. By having at least one of the first urging means and the second urging means common to each of the plurality of cams 136, it is possible to reduce the number of parts and to prevent variations in the behavior of the cams 136.

[0044] The above has described the case where the present invention is applied to a two-way clutch, but the present invention may also be applied to a selectable clutch whose operating modes can be switched between four operating modes, including a forward direction lock mode and / or a reverse direction lock mode, which prohibit relative rotation of the inner and outer rings in either the forward or reverse direction.

[0045] [Fourth embodiment] As shown in FIG. 13 , a cam clutch according to a fourth embodiment of the present invention has a configuration similar to that of the cam clutch 100 according to the first embodiment, except that it has a first switching means 170a that changes the biasing force of one of the first biasing means 150 and the second biasing means 155 applied to the first cam 136a, and a second switching means 170b that changes the biasing force of one of the first biasing means 150 and the second biasing means 155 applied to the second cam 136b.

[0046] The first switching means 170a and the second switching means 170b are provided so as to be movable in the axial direction independently of each other between a first fixed position and a second fixed position located on one axial end side of the first fixed position.

[0047] The first switching means 170a is composed of a plurality of columnar first cam position change portions 171a disposed between the inner ring 110 and the outer ring 120 and extending in the axial direction, and a pair of substantially annular plate-shaped first fixing members 175a fixed to both end faces of each first cam position change portion 171a. The first fixing members 175a each have an annular plate portion 176a and a plurality of inward protruding pieces 176b formed to protrude radially inward from the inner peripheral edge of the annular plate portion 176a. The inward protruding pieces 176b are arranged at predetermined intervals in the circumferential direction, and the first cam position change portions 171a are fixed to the inward protruding pieces 176b so as to be aligned on the same circumference. The first cam position change portions 171a have a configuration similar to that of the cam position change portion 171 in the cam clutch 100 according to the first embodiment. That is, in this embodiment, the first cam position changing portion 171a is configured so that, by axial movement of the first switching means 170a, the first biasing means 150 can be changed to a state where it can bias the first cam 136a with a biasing force greater than the biasing force of the second biasing means 155, in other words, the biasing force of the second biasing means 155 can be changed to be smaller than the biasing force of the first biasing means 150. The first cam position changing portion 171a is arranged in a state where it is inserted into the insertion hole 143 of the cage ring 140 so as to be positioned between adjacent cam pairs 135 and is axially movably inserted into the insertion hole 143 of the cage ring 140.

[0048] The second switching means 170b is composed of a plurality of columnar second cam position change portions 171b disposed between the inner ring 110 and the outer ring 120 and extending in the axial direction, and a pair of substantially annular plate-shaped second fixing members 175b fixed to both end faces of each second cam position change portion 171b. The second fixing member 175b has an annular plate portion 177a having an outer diameter dimension that allows it to be fitted radially inward of the first fixing member 175a, and a plurality of outward protruding pieces 177b formed to protrude radially outward from the outer periphery of the annular plate portion 177a so as to be fitted between the inward protruding pieces 176b of the first fixing member 175a via gaps. The outward protruding pieces 177b are arranged at predetermined intervals in the circumferential direction, and the second cam position change portion 171b is fixed to each outward protruding piece 177b so as to be aligned coaxially with the first cam position change portion 171a. In this embodiment, like the first cam position changing portion 171a, the second cam position changing portion 171b is configured so that, by axial movement of the second switching means 170b, the first biasing means 150 can be changed to a state where it can bias the second cam 136b with a biasing force greater than the biasing force of the second biasing means 155; in other words, the biasing force of the second biasing means 155 can be changed to be smaller than the biasing force of the first biasing means 150. The second cam position changing portion 171b is arranged in a state where it is inserted into the insertion hole 143 of the cage ring 140 so as to be positioned between adjacent cam pairs 135 and is axially movably inserted therethrough.

[0049] 14A, when first switching means 170a and second switching means 170b are both in the first fixed position, the movable piece of first biasing means 150 for first cam 136a and the movable piece of first biasing means 150 for second cam 136b are in contact with biasing force changing portion 173 of first cam position changing portion 171a and biasing force changing portion 173 of second cam position changing portion 171b, respectively, as shown in FIG. 14B, and the biasing force of first biasing means 150 is smaller than the biasing force of second biasing means 155, or the biasing force of first biasing means 150 is released. Therefore, both first cam 136a and second cam 136b are biased to rotate in the disengagement direction, and both first cam 136a and second cam 136b are spaced from the outer circumferential surface of inner ring 110 and are in a non-contact state. Therefore, the operation mode of the cam clutch is a bidirectional free mode that allows relative rotation of the inner ring 110 and the outer ring 120 in both forward and reverse directions.

[0050] As shown in Fig. 15A, when only the first switching means 170a is moved from the first fixed position to the second fixed position at one axial end, the first cam position changing portion 171a presses the first biasing means 150 against the first cam 136a in the compression direction, as shown in Fig. 15B. As a result, the biasing force of the first biasing means 150 becomes larger than the biasing force of the second biasing means 155, i.e., the biasing force of the second biasing means 155 becomes smaller relative to the biasing force of the first biasing means 150, and the first cam 136a is biased to rotate in the meshing direction. As a result, the first cam 136a comes into sliding contact with the inner ring 110 and the outer ring 120, and when the inner ring 110 is rotated in the forward direction (clockwise in FIG. 15B) or the outer ring 120 is rotated in the reverse direction (counterclockwise in FIG. 15B), the first cam 136a immediately enters an engagement standby state in which it can engage with the inner ring 110 and the outer ring 120. Therefore, the operating mode of the cam clutch is switched to a forward rotation direction lock mode in which relative rotation of the inner ring 110 and the outer ring 120 is prohibited in the forward rotation direction.

[0051] On the other hand, as shown in Fig. 16A, when only second switching means 170b is moved from the first fixed position to the second fixed position at one axial end, second cam position changing portion 171b presses first biasing means 150 against second cam 136b in the compression direction, as shown in Fig. 16B. As a result, the biasing force of first biasing means 150 becomes larger than the biasing force of second biasing means 155, i.e., the biasing force of second biasing means 155 becomes smaller relative to the biasing force of first biasing means 150, and second cam 136b is biased to rotate in the meshing direction. As a result, the second cam 136b comes into sliding contact with the inner ring 110 and the outer ring 120, and when the inner ring 110 is rotated in the reverse direction (counterclockwise in FIG. 16B) or the outer ring 120 is rotated in the forward direction (clockwise in FIG. 16B), the second cam 136b immediately enters an engagement standby state in which it can engage with the inner ring 110 and the outer ring 120. Therefore, the operating mode of the cam clutch is switched to a reverse direction lock mode in which relative rotation of the inner ring 110 and the outer ring 120 is prohibited in the reverse direction.

[0052] 17A , when both the first switching means 170a and the second switching means 170b are moved from the first fixed position to the second fixed position at one axial end, the biasing force of the first biasing means 150 becomes greater than the biasing force of the second biasing means 155, i.e., the biasing force of the second biasing means 155 becomes smaller relative to the biasing force of the first biasing means 150, biasing the first cam 136a and the second cam 136b to rotate in the meshing direction, as shown in FIG. 17B . As a result, the first cam 136a and the second cam 136b come into sliding contact with the inner ring 110 and the outer ring 120, and either the first cam 136a or the second cam 136b enters an meshing standby state in which they can immediately engage with the inner ring 110 and the outer ring 120. Therefore, the operating mode of the cam clutch is switched to a bidirectional lock mode in which relative rotation of the inner ring 110 and the outer ring 120 is prohibited in both the forward and reverse directions.

[0053] As described above, with the cam clutch, by selectively rotating either or both of the first cam 136a and the second cam 136b, it is possible to switch between four operating modes: a bidirectional lock mode in which torque can be transmitted in both the forward and reverse directions; a forward lock mode in which torque can be transmitted only in the forward direction; a reverse lock mode in which torque can be transmitted only in the reverse direction; and a bidirectional free mode in which the clutch rotates freely in both the forward and reverse directions.

[0054] [Fifth Embodiment] As shown in FIG. 18 , a cam clutch according to a fifth embodiment of the present invention includes a first cam mechanism 131 a and a second cam mechanism 131 b, and is configured to be switchable in operation mode among a bidirectional lock mode in which torque is transmitted between the inner and outer rings by the first cam mechanism 131 a, a bidirectional lock mode in which torque is transmitted between the inner and outer rings by the second cam mechanism 131 b, and a bidirectional free mode in which torque transmission is blocked in both the forward and reverse directions.

[0055] In the cam clutch of this embodiment, a first inner ring 110a and a second inner ring 110b having the same configuration are arranged side by side in the axial direction, and an outer ring 120 is arranged coaxially with and rotatable relative to the first inner ring 110a and the second inner ring 110b. A first cam mechanism 131a is arranged between the first inner ring 110a and the outer ring 120, and a second cam mechanism 131b is arranged between the second inner ring 110b and the outer ring 120. Although not shown, a configuration may also be adopted in which a first outer ring and a second outer ring having the same configuration are arranged side by side in the axial direction, an inner ring is arranged coaxially with and rotatable relative to the first outer ring and the second outer ring, and the first cam mechanism and the second cam mechanism are arranged between the inner ring and the first outer ring and between the inner ring and the second outer ring, respectively.

[0056] The first cam mechanism 131a and the second cam mechanism 131b have the same configuration as the cam mechanism 130 in the cam clutch 100 according to the first embodiment, and as shown in FIG. 19A, the first cam mechanism 131a and the second cam mechanism 131b are arranged in such a manner that the leaf spring serving as the first biasing means 150 is convex outward in the axial direction.

[0057] In this embodiment, the cam position changer 171 of the switching means 170 includes a first-end biasing force application portion 172a, a first biasing force change portion 173a connected to the other axial end of the first biasing force application portion 172a, a biasing force release portion 174 connected to the other axial end of the first biasing force change portion 173a, a second biasing force change portion 173b connected to the other axial end of the biasing force release portion 174, and an other-end biasing force application portion 172b connected to the other axial end of the second biasing force change portion 173b. The first-end biasing force application portion 172a and the other-end biasing force application portion 172b are prismatic and have the same radial dimension. The biasing force release portion 174 is prismatic and has a smaller radial dimension than the first-end biasing force application portion 172a and the other-end biasing force application portion 172b. The first biasing force changing portion 173a is configured so that its radially inner surface extends at an inclination radially outward toward the other axial end. The second biasing force changing portion 173b is configured so that its radially inner surface extends at an inclination radially inward toward the other axial end. Reference numeral 178 in Fig. 19A denotes a cylindrical extension portion for fixing the cam position changing portion 171 to the fixing member 175 at one axial end.

[0058] 19A , when the switching means 170 is in the first fixed position, the first biasing means 150 in the first cam mechanism 131a is in contact with the outer surface of the one-end biasing force applying portion 172a of the cam position changing portion 171, and the biasing force of the first biasing means 150 is greater than the biasing force of the second biasing means 155. As a result, the first cam 136a and the second cam 136b in the first cam mechanism 131a are both biased to rotate in the meshing direction, and the first cam 136a and the second cam 136b are both in sliding contact with the first inner ring 110a and the outer ring 120, and either the first cam 136a or the second cam 136b is in a meshing standby state in which they can immediately engage with the first inner ring 110a and the outer ring 120. On the other hand, the first biasing means 150 in the second cam mechanism 131b is not in contact with the cam position changing portion 171, and the biasing force of the first biasing means 150 is released. Therefore, the first cam 136a and the second cam 136b in the second cam mechanism 131b are both biased to rotate in the disengagement direction, and the first cam 136a and the second cam 136b are spaced apart from the outer peripheral surface of the second inner ring 110b and are in a non-contact state. Therefore, the operating mode of the cam clutch is a bidirectional lock mode that prohibits relative rotation of the first inner ring 110a and the outer ring 120 in both the forward and reverse directions.

[0059] 19B , when the switching means 170 is moved from the first fixed position to the second fixed position at one axial end, all of the first biasing means 150 in the first cam mechanism 131a and the second cam mechanism 131b are out of contact with the cam position changing portion 171, and the biasing force of the first biasing means 150 is released. As a result, the first cam 136a and the second cam 136b in the first cam mechanism 131a and the second cam mechanism 131b are both biased to rotate in the disengagement direction, and the first cam 136a and the second cam 136b are spaced from the outer peripheral surfaces of the first inner ring 110a and the second inner ring 110b and are in a non-contact state. Therefore, the operating mode of the cam clutch is switched to a bidirectional free mode that allows relative rotation between the first inner ring 110a and the outer ring 120 and relative rotation between the second inner ring 110b and the outer ring 120 in both forward and reverse directions.

[0060] 19C , when switching means 170 is moved from the first fixed position to a third fixed position which is further axially closer to one end than the second fixed position, first biasing means 150 in first cam mechanism 131a comes out of contact with cam attitude changing portion 171, and the biasing force of first biasing means 150 is released. As a result, first cam 136a and second cam 136b in first cam mechanism 131a are both biased to rotate in the meshing release direction, and first cam 136a and second cam 136b are spaced apart from the outer circumferential surface of first inner ring 110a and come out of contact. On the other hand, first biasing means 150 in second cam mechanism 131b comes into contact with the outer surface of the other-end biasing force applying portion 172b of cam position changing portion 171, and the biasing force of first biasing means 150 becomes larger than the biasing force of second biasing means 155, that is, the biasing force of second biasing means 155 becomes smaller relative to the biasing force of first biasing means 150. As a result, both first cam 136a and second cam 136b in second cam mechanism 131b are biased to rotate in the meshing direction, and both first cam 136a and second cam 136b come into sliding contact with second inner ring 110b and outer ring 120, and either first cam 136a or second cam 136b enters an meshing standby state in which they can immediately engage with second inner ring 110b and outer ring 120. Therefore, the operation mode of the cam clutch is switched to a bidirectional lock mode in which the relative rotational movement of the second inner ring 110b and the outer ring 120 is prohibited in both the forward and reverse directions.

[0061] Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above embodiments, and various design modifications are possible without departing from the scope of the present invention as defined in the claims. For example, the cam clutch according to each of the above embodiments has been described as including two types of cams, a first cam and a second cam, which have different meshing directions. However, as shown in FIG. 20 , the cam clutch may include only one type of cam 136. In this cam clutch, for example, when the switching means 170 is in the first fixed position, the biasing force of the first biasing means 150 is smaller than the biasing force of the second biasing means 155, or the biasing force of the first biasing means 150 is released, and the cam 136 is spaced from the outer circumferential surface of the inner ring 110 and in a non-contact state. When the switching means 170 is moved from the first fixed position to the second fixed position at one axial end, the biasing force of the first biasing means 150 becomes greater than the biasing force of the second biasing means 155. In other words, the biasing force of the second biasing means 155 becomes smaller relative to the biasing force of the first biasing means 150. As a result, the cam 136 immediately enters an engagement standby state in which it can engage with the inner ring 110 and the outer ring 120. In this way, by applying the present invention to a one-way clutch, it is possible to make it function as a selectable clutch that can realize a bidirectional free mode. Although the illustrated embodiment is configured without an interlocking member, it may also be configured with an interlocking member that interlocks the rotational movements of all the cams. With such a configuration, there is no variation in the rotational movements of the multiple cams, thereby achieving stable operation.

[0062] DESCRIPTION OF SYMBOLS 100 Cam clutch 110 Inner ring 110a First inner ring 110b Second inner ring 120 Outer ring 130 Cam mechanism 131a First cam mechanism 131b Second cam mechanism 135 Cam pair 136 Cam 136a First cam 136b Second cam 137 Rotation shaft portion 138 Mounting groove 139a Notch portion 139b Step portion 140 Cage ring 141 Annular plate-shaped member 142 Retaining hole 143 Insertion hole 144 Second biasing means support portion 145 Spacer member 150 First biasing means 155 Second biasing means 156a... Winding portion 156b... Connecting portion 157... Ring portion 158... Connecting portion 159a... First leaf spring portion 159b... Second leaf spring portion 160... Cam interlocking member 161... Base portion 162... Claw portion 170... Switching means 170a... First switching means 170b... Second switching means 171... Cam position changing portion 171a... First cam position changing portion 171b... Second cam position changing portion 172... Urging force applying portion 172a... One end side urging force applying portion 172b... Other end side urging force applying portion 173... Urging force changing portion 173a... First urging force changing portion 173b... Second urging force changing portion 174... Urging force release portion 175: Fixed member 175a: First fixed member 175b: Second fixed member 176a: Annular plate portion 176b: Inwardly protruding piece portion 177a: Annular plate portion 177b: Outwardly protruding piece portion 178: Extension portion

Claims

1. 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 first biasing means for biasing the cam to rotate in the meshing direction, and a switching means configured to be able to switch operating modes by forcibly rotating the cam, further comprising a second biasing means for biasing the cam to rotate in the disengagement direction with a biasing force different in magnitude from the biasing force of the first biasing means, and the switching means having a cam position changing portion configured to be able to change the biasing force of one of the first and second biasing means which has a larger biasing force on the same cam to be smaller than the biasing force of the other biasing means.

2. A cam clutch as claimed in claim 1, further comprising a cam interlocking member for interlocking the rotational movements of all the cams.

3. A cam clutch as described in claim 2, characterized in that the cams include a first cam and a second cam which have mutually different meshing directions, and the cam interlocking member is configured such that when one of the first cam and the second cam rotates in the meshing direction, the other cam rotates in the disengaging direction.

4. A cam clutch as described in claim 1 or 2, characterized in that the switching means is provided so as to be movable in the axial direction with the cam position changing portion positioned between adjacent cams, and the cam position changing portion is configured so that the biasing force of the first biasing means against the cam can be changed by axial movement of the switching means.

5. A cam clutch as set forth in claim 4, wherein the biasing force of said first biasing means is smaller than the biasing force of said second biasing means for the same cam, and said cam position changing section is configured to be able to change said first biasing means to a state in which it can be biased with a biasing force larger than the biasing force of said second biasing means.

6. A cam clutch as described in claim 4, wherein the biasing force of said first biasing means is greater than the biasing force of said second biasing means with respect to the same cam, and said cam position changing section is configured to be able to change said first biasing means to a state in which it can be biased with a biasing force smaller than the biasing force of said second biasing means, or to a state in which the biasing force with respect to said cam is released.

7. A cam clutch according to claim 1 or 2, wherein at least one of said first biasing means and said second biasing means is common to each of said plurality of cams.

8. A cam clutch as described in claim 3, characterized in that the switching means includes first switching means for changing the biasing force of one of the first biasing means and the second biasing means applied to the first cam, and second switching means for changing the biasing force of one of the first biasing means and the second biasing means applied to the second cam.

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