One-way clutch

Abstract

To provide an engage-type one-way clutch which can control engagement timing.SOLUTION: A one-way clutch 10 includes: an outer ring 1 having a substantially annular outer ring raceway surface 1a; an inner ring 2 radially spaced from the outer ring 1 and disposed concentrically in a relatively rotatable manner, and having a substantially annular inner ring raceway surface 2a; a plurality of sprags 3 that are provided between the outer ring 1 and the inner ring 2, and transmit a torque by engagement with the inner ring raceway surface 2a and the outer ring raceway surface 1a; an annular holder 4 for holding the sprags 3; and a coil spring 5 for urging the sprag 3 against the inner ring 2. When the one-way clutch 10 is at rest, the sprag 3 does not engage with the outer ring 1. When the one-way clutch 10 is at a first rotation speed or more, the sprag 3 auto-rotates due to a centrifugal force CF applied to the sprag 3 and comes into contact with the inner ring 2 and the outer ring 1, transmitting the torque.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a one-way clutch, and more particularly to an engagement type sprag one-way clutch. [Background technology]

[0002] One-way clutches are used in drive systems for automobiles, motorcycles, industrial machinery, etc. as components for torque transmission, backstops, etc. Generally, one-way clutches with a rotating outer ring are classified into two types: an engaging type that emphasizes meshing, and a disengaging type that emphasizes low drag.

[0003] Patent Document 1 discloses a disengage-type one-way clutch configured such that when the inner and outer rings are stopped or rotating at a low rotational speed, the inner ring engages with the outer ring to transmit power to the outer ring, and the clutch spins idly if the outer ring overruns. Patent Document 2 discloses an engage-type one-way clutch configured such that when torque is applied to the inner ring from an unloaded state, the cam oscillates in the torque transmission direction and engages with the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, transmitting torque from the inner ring to the outer ring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-292140 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-118268 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for an engagement type one-way clutch that places emphasis on meshing, as opposed to the disengagement type one-way clutch disclosed in Patent Document 1. There is also a demand for an engagement type one-way clutch with a different mechanism than the engagement type one-way clutch disclosed in Patent Document 2.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide an engagement type one-way clutch that allows control of engagement timing. [Means for solving the problem]

[0007] In order to achieve the above object, the one-way clutch of the present invention comprises an outer ring having a substantially annular outer ring raceway surface, an inner ring arranged concentrically with the outer ring and spaced radially from it so as to be freely rotatable relative to it, the inner ring having a substantially annular inner ring raceway surface, a plurality of cams arranged between the outer ring and the inner ring and transmitting torque by engaging with the inner ring raceway surface and the outer ring raceway surface, an annular retainer that holds the cams, and a biasing member that biases the cams to press them against the inner ring, wherein when the one-way clutch is stopped, the cams do not engage with the outer ring, and when the one-way clutch is at or above a first rotation speed, the cams rotate on their own axis due to the centrifugal force acting on them, coming into contact with the inner ring and the outer ring, thereby transmitting the torque. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an engagement type one-way clutch that allows control of engagement timing. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a side view of an engagement type one-way clutch 10 according to a first embodiment of the present invention, FIG. 1B is a front view of the one-way clutch 10, and FIG. 1C is a partial perspective view of the one-way clutch 10. [Figure 2]1A is a front view of a sprag 3 of the present invention, and FIG. 1B is a front view of a conventional sprag 300. [Figure 3] 4(A) to 4(C) are cross-sectional views showing the operation of the sprag 3 of the present invention. [Figure 4] 1A to 1C are cross-sectional views showing the operation of a conventional sprag 300. [Figure 5] FIG. 1 is a front view of an engagement type one-way clutch 20 according to a second embodiment of the present invention.

[0010] Example 1 A first embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Fig. 1(A) is a side view of a sprag-type one-way clutch 10 of the present invention (hereinafter referred to as "one-way clutch"), Fig. 1(B) is a front view of the one-way clutch 10, and Fig. 1(C) is a partial perspective view of the one-way clutch 10, with the cage 4 and outer ring 1 omitted. The engage-type one-way clutch 10 of the first embodiment has an outer ring 1 having a substantially annular outer ring raceway surface 1a, and an inner ring 2 that is radially spaced from the outer ring 1 and arranged concentrically so as to be rotatable relative to it, and has a substantially annular inner ring raceway surface 2a.

[0011] The one-way clutch 10 further includes sprags 3 (cams), an annular cage 4 that holds the sprags 3, and coil springs 5 ​​(biasing members) that bias the sprags 3 so as to press them against the inner ring raceway surface 2a of the inner ring 2. A plurality of sprags 3 are provided at equal intervals in the circumferential direction. The plurality of sprags 3 are arranged between the outer ring 1 and the inner ring 2, and are torque transmission members that transmit torque from the inner ring 2 to the outer ring 1 by engaging with the outer ring raceway surface 1a and the inner ring raceway surface 2a. The cage 4 is arranged between the outer ring 1 and the inner ring 2.

[0012] FIG. 2(A) is a front view of a sprag 3 of the present invention, showing the sprag 3 engaged with the outer ring raceway surface 1a and the inner ring raceway surface 2a. The sprag 3 is a columnar member whose circumferential surface is composed of curved surfaces and approximately straight lines. The sprag 3 has a shape that combines an approximately semicircular portion 3c, an outer cam surface 3a (first approximately straight portion) and an inner cam surface 3b (second approximately straight portion) extending from both ends of the approximately semicircular portion 3c, and a bulge portion 3d that bulges outward from the line connecting the ends of the outer cam surface 3a and the inner cam surface 3b. The bulge portion 3d is mountain-shaped, and the connection portion between one end of the contour of the bulge portion 3d and the end of the outer cam surface 3a forms an outer engagement portion 3e1 (first engagement portion) and is smoothly continuous. The other end of the contour of the bulge portion 3d and the end of the inner cam surface 3b are smoothly connected. Furthermore, one end of the contour of the approximately semicircular portion 3c smoothly connects to the end of the outer cam surface 3a, and the other end of the contour of the approximately semicircular portion 3c smoothly connects to the end of the inner cam surface 3b, forming inner engagement portion 3e2 (second engagement portion). Outer engagement portion 3e1 is located radially opposite inner engagement portion 3e2.

[0013] A groove 3g is formed inside the sprag 3, extending circumferentially around the inner ring 2 or the outer ring 1. The groove 3g penetrates the radially outer portion of the sprag 3 in the circumferential direction. A vertex 3v is formed inside the sprag 3, where the angle of the groove 3g changes circumferentially. The groove 3g is formed in a circumferentially mountain-shaped manner, i.e., formed by two approximately straight lines whose angle changes at the vertex 3v. The vertex 3v is located to the right of the center of gravity G of the sprag 3 on the page, i.e., downstream in the idling direction A1 of the outer ring 1. A single annular coil spring 5 is installed through each groove 3g of each sprag 3. The coil spring 5 abuts against each sprag 3 at the vertex 3v, applying a biasing force F to each sprag 3 and biasing each sprag 3 toward the inner ring raceway surface 2a.

[0014] FIG. 2(B) is a front view of a conventional sprag 300, showing the sprag 300 engaged with the outer ring raceway 1a and the inner ring raceway 2a. Differences from the sprag 3 of the present invention will be described, and explanations of components with the same configuration will be omitted. The sprag 300 is a columnar member whose circumferential surface is composed of curved surfaces and substantially straight lines. The sprag 300 has a shape that combines a substantially semicircular portion 300c and a bulging portion 300d that bulges outward from a substantially straight line connecting both ends of the substantially semicircular portion 300c. The bulging portion 300d is mountain-shaped with an apex, and one side of the contour of the bulging portion 300d forms an outer cam surface 300a with a substantially straight shape. The apex of the sprag 300 can engage with the outer ring raceway 1a, and the apex is an outer engaging portion 300e1. Furthermore, inner engagement portion 300e2 is present in approximately semicircular portion 300c that is radially opposed to outer engagement portion 300e1. Furthermore, one end of the contour of approximately semicircular portion 300c smoothly connects to the end of outer cam surface 300a, and the other end of the contour of bulging portion 300d smoothly connects to the end of the contour of approximately semicircular portion 300c.

[0015] Conventional sprags 300 each have a groove 300g formed inside them that extends circumferentially around the inner ring 2 or outer ring 1. The groove 300g penetrates the radially outer portion of the sprag 300 in the circumferential direction. The groove 300g has a vertex 300v formed inside the sprag 300, where the angle of the groove 300g changes circumferentially. The groove 300g is formed to have a circumferentially mountain-like shape, i.e., two straight lines that change angle at the vertex 300v. The vertex 300v is located to the left of the center of gravity G of the sprag 300 in the drawing, i.e., in the meshing direction B1 of the outer ring 1. An annular coil spring 5 is installed in each sprag 300, penetrating each groove 300g. The coil spring 5 abuts against each sprag 300 at the vertex 300v, applying a biasing force F to each sprag 300 and biasing each sprag 300 toward the inner ring raceway surface 2a.

[0016] Next, the operation of the sprags 3 according to the first embodiment of the present invention will be described. Figures 3(A) to 3(C) are partial axial cross-sectional views of the one-way clutch 10 according to the first embodiment of the present invention in various states of the one-way clutch 10, showing the behavior of the sprags 3. Figure 3(A) shows the sprags 3 when the one-way clutch 10 is stopped. A biasing force F acts on the apex 3v of the sprags 3 against the inner ring raceway surface 2a by the coil spring 5, and the sprags 3 are always biased radially inward. When the one-way clutch 10 is stopped, the inner cam surface 3b of the sprags 3 contacts the inner ring raceway surface 2a of the inner ring 2, and the outer cam surface 3a of the sprags 3 does not contact the outer ring raceway surface 1a of the outer ring 1. That is, a clearance C1 exists between the outer cam surface 3a and the outer ring raceway surface 1a. Therefore, when the one-way clutch 10 is stopped, each sprag 3 is urged toward the inner diameter side by the urging force F of the coil spring 5, so that the inner cam surface 3b is always in contact with the inner ring raceway surface 2a and the outer cam surface 3a is separated from the outer ring raceway surface 1a. Therefore, no torque is transmitted between the outer ring 1 and the inner ring 2.

[0017] Figure 3(B) shows the sprags 3 when the one-way clutch 10 is at or above a predetermined low rotation speed. The meshing direction B2 of the inner ring 2 is opposite to the meshing direction B1 of the outer ring 1, and the idling direction A2 of the inner ring 2 is opposite to the idling direction A1 of the outer ring 1. Both the outer ring 1 and the inner ring 2 are rotating, but no torque is yet transmitted between them. A biasing force F is applied to the apex 3v of the sprag 3 by the coil spring 5, biasing the sprag 3 radially inward. Then, as the one-way clutch 10 rotates, a centrifugal force CF is applied to the center of gravity G of the sprag 3. When the one-way clutch 10 rotates at a predetermined low rotation speed (second rotation speed) or higher, but lower than the high rotation speed (described later), centrifugal force CF acting on the center of gravity G of the sprags 3 moves the sprags 3 radially outward. The outer cam surfaces 3a of the sprags 3 contact the outer ring raceway 1a of the outer ring 1, and clearance C1 disappears. Meanwhile, the sprags 3 no longer contact the inner ring raceway 2a, and clearance C2 is generated between the inner cam surfaces 3b and the inner ring raceway 2a. Therefore, when the one-way clutch 10 is rotating at the predetermined low rotation speed, centrifugal force CF moves each sprag 3 radially outward, and the outer cam surfaces 3a contact the outer ring raceway 1a. Therefore, torque is not transmitted between the outer ring 1 and the inner ring 2. In other words, the extension of the line of action of centrifugal force CF does not yet overlap with the outer engagement portion 3e1. Furthermore, the outer engaging portion 3e1 has not yet come into contact with the outer ring raceway surface 1a, and there is a gap between them.

[0018] FIG. 3(C) shows the sprags 3 when the one-way clutch 10 is rotating at or above a predetermined high rotational speed. The sprags 3 are biased by the coil springs 5 ​​with a biasing force F. When the rotation of the one-way clutch 10 reaches or exceeds the predetermined high rotational speed (first rotational speed), a centrifugal force CF greater than that in the state shown in FIG. 3(B) acts on the center of gravity G of the sprags 3. The centrifugal force CF is much greater than the biasing force F, and a rotational moment M is generated in the sprags 3 so as to eliminate the gap between the outer engagement portion 3e1 and the outer ring raceway surface 1a, causing the sprags 3 to rotate counterclockwise. As a result, the outer engagement portion 3e1 extending from the end of the outer cam surface 3a engages with the outer ring raceway surface 1a, and the inner engagement portion 3e2 extending from the end of the inner cam surface 3b engages with the inner ring raceway surface 2a, eliminating the clearance C2. Therefore, when the one-way clutch 10 is rotating at a predetermined high rotation speed, the one-way clutch 10 is in an engaged state, and torque is transmitted between the outer ring 1 and the inner ring 2. When the one-way clutch 10 is rotating at a predetermined high rotation speed, the one-way clutch 10 becomes an engaged type one-way clutch.

[0019] Next, the operation of the conventional sprag 300 will be described. Figures 4(A) to 4(C) show the behavior of the conventional sprag 300 in various states. Figure 4(A) shows the sprag 300 when a conventional disengage-type one-way clutch is stopped. A biasing force F acts on the apex 300v of the sprag 300 against the inner ring raceway surface 2a by the coil spring 5, constantly biasing the sprag 300 radially inward. When the conventional one-way clutch is stopped, the inner engagement portion 300e2 on the approximately semicircular portion 300c of the sprag 300 contacts the inner ring raceway surface 2a of the inner ring 2. Furthermore, the outer engagement portion 300e1 extending from the end of the outer cam surface 300a contacts the outer ring raceway surface 1a of the outer ring 1. Therefore, when the conventional one-way clutch is stopped, the outer engagement portion 300e1 contacts the outer ring raceway surface 1a, and the inner engagement portion 300e2 contacts the inner ring raceway surface 2a. When the conventional one-way clutch is stopped, the conventional one-way clutch is in an engaged state, and torque can be transmitted between the outer ring 1 and the inner ring 2.

[0020] FIG. 4(B) shows sprags 300 of a conventional one-way clutch at a low rotation speed. A biasing force F is applied to vertices 300v of sprags 300 by coil springs 5, biasing sprags 300 radially inward. When the conventional one-way clutch begins to rotate, a centrifugal force CF acts on the center of gravity G of sprags 300. When the conventional one-way clutch is rotating at a speed below a predetermined low rotation speed, the biasing force F and centrifugal force CF act on sprags 300, but sprags 300 do not rotate. The inner engaging portion 300e2 of sprags 300 contacts the inner ring raceway surface 2a of the inner ring 2, and the outer engaging portion 300e1 contacts the outer ring raceway surface 1a of the outer ring 1. When the conventional one-way clutch is rotating at a speed below the predetermined low rotation speed, the conventional one-way clutch is engaged, and torque is transmitted between the outer ring 1 and the inner ring 2.

[0021] FIG. 4(C) shows sprag 300 when a conventional one-way clutch is rotating at or above a predetermined high rotational speed. Sprag 300 is biased by coil spring 5 with biasing force F. When the rotation of the conventional one-way clutch exceeds the predetermined high rotational speed, a centrifugal force CF greater than that shown in FIG. 4(B) acts on the center of gravity G of sprag 300 due to the rotation. The relationship between centrifugal force CF and biasing force F generates a rotational moment M in sprag 300, causing sprag 300 to rotate clockwise. As a result, outer cam surface 300a extending from outer engaging portion 300e1 contacts outer ring raceway surface 1a, but inner engaging portion 300e2 on approximately semicircular portion 300c does not contact inner ring raceway surface 2a, creating clearance C3 between approximately semicircular portion 300c and inner ring raceway surface 2a. Therefore, when a conventional one-way clutch is rotating at a predetermined high rotation speed or higher, the outer cam surface 300a of each sprag 300 comes into contact with the outer ring raceway surface 1a, and torque is not transmitted between the outer ring 1 and the inner ring 2.

[0022] According to the first embodiment of the present invention, it is possible to provide an engagement type one-way clutch that allows control of engagement timing. Since the engagement type one-way clutch engages under different conditions than conventional disengagement type one-way clutches, it is possible to expand the range of uses for one-way clutches.

[0023] Example 2 5 is a front view of an engageable one-way clutch 20 according to a second embodiment of the present invention. Compared with the first embodiment, the same components are designated by the same reference numerals and their description will be omitted.

[0024] The one-way clutch 20 of the second embodiment is provided with weights 6 between the sprags 3, and the timing of meshing can be adjusted by the weights 6. More specifically, the biasing force F of the coil spring 5 can be adjusted by the centrifugal force CF acting on the weights 6.

[0025] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes are possible within the scope of the invention. [Explanation of symbols]

[0026] 1 outer ring 1a Outer ring raceway surface 2. Inner circle 2a Inner ring raceway surface 3 Sprag (cam) 3c Semicircular part 3a outer cam surface (first substantially straight portion) 3b Inner cam surface (second approximately straight portion) 3d bulge 3e1 outer engaging portion (first engaging portion) 3e2 Inner engagement portion (second engagement portion) 3g groove 3v apex 4 Cage 5 Coil spring (biasing member) 6 Weight 10 One-way clutch 3a Outer cam surface A1 Idling direction F biasing force CF centrifugal force

Claims

1. an outer ring having a substantially annular outer ring raceway surface; an inner ring having a substantially annular inner ring raceway surface, the inner ring being concentrically arranged and spaced apart from the outer ring in the radial direction and rotatable relative to the outer ring; a plurality of cams disposed between the outer ring and the inner ring, the cams engaging with the inner ring raceway surface and the outer ring raceway surface to transmit torque; an annular retainer that holds the cam; a biasing member that biases the cam so as to press it against the inner ring, When the one-way clutch is stopped, the cam does not engage with the outer ring, When the one-way clutch rotates at a first rotation speed or higher, the cam rotates on its axis due to centrifugal force acting on the cam, contacting the inner ring and the outer ring to transmit the torque.

2. A groove is formed inside the cam, extending in a circumferential direction and having an apex whose angle changes in the circumferential direction, 2. The one-way clutch according to claim 1, wherein the biasing member abuts against the cam at the apex to apply a biasing force to the cam.

3. 3. The one-way clutch according to claim 2, wherein when the rotational speed of the one-way clutch is equal to or greater than a second rotational speed that is smaller than the first rotational speed, the centrifugal force acting on the cam becomes greater than the biasing force, and the cam comes into contact with the outer ring and is not in contact with the inner ring.

4. 3. The one-way clutch according to claim 2, wherein the apex in the circumferential direction of the one-way clutch is located downstream of the center of gravity of the cam in the direction of idling of the outer ring.

5. the cam has a shape that combines a substantially semicircular portion, a first substantially linear portion and a second substantially linear portion that extend from both ends of the substantially semicircular portion, respectively, and a bulging portion that bulges outward from a line that connects the ends of the first and second substantially linear portions, When the one-way clutch has a rotation speed greater than the second rotation speed, the first substantially straight portion contacts the outer ring raceway surface, 4. The one-way clutch according to claim 3, wherein the second substantially straight portion contacts the inner ring raceway surface when the one-way clutch is stopped.

6. 6. The one-way clutch according to claim 5, wherein, when the one-way clutch is rotating at or above the first rotation speed, a second engagement portion located between the approximately semicircular portion and the second approximately straight portion engages with the inner ring raceway surface, and a first engagement portion located radially opposite the second engagement portion engages with the outer ring raceway surface.

7. 4. The one-way clutch according to claim 3, wherein weights are arranged on both sides of the cam in the circumferential direction of the one-way clutch, and the first rotation speed and the second rotation speed can be adjusted by changing the weights.

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