JP2017166599A - Oneway clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a oneway clutch which blocks power transmission when an excessive load is applied thereto, and can automatically transmit power accompanied by the elimination of the excessive load.SOLUTION: A oneway clutch 10 comprises: an inner ring 11; an outer ring 12 which is arranged at the outside of the inner ring 11 in a radial direction concentrically therewith, and has an internal peripheral face 12a for forming a wedge-shaped space S between an external peripheral face 11a of the inner ring 11 and itself; rollers 13 which are arranged in the wedge-shaped space S, and engaged with the external peripheral face 11a of the inner ring 11 and an internal peripheral face 12a of the outer ring 12 at a narrow side of the wedge-shaped space S; and an energization member 15 for energizing the rollers 13 toward the narrow side of the wedge-shaped space S. A first cam face 21 engaged with the rollers 13 and a second cam face 22 which is arranged adjacently to an end part of the narrow side at the first cam face 21, and releases the engagement with the rollers 13 by expanding a wedge angle in the wedge-shaped space S more than the first cam face 21 are formed at either of the external peripheral face 11a of the inner ring 11 and the internal peripheral face 12a of the outer ring 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a one-way clutch having a torque limiter function.

For example, in Patent Document 1 below, a one-way clutch is provided in a path for transmitting the rotational power of an automobile engine to a compressor for an air conditioner so as to stabilize the rotation of the compressor by absorbing the rotational fluctuation of the engine. Is disclosed.
The one-way clutch described in Patent Document 1 is provided between an inner ring integrally provided on a pulley that is rotated by engine power, an outer ring fixed to a rotation shaft of a compressor, and an inner ring and an outer ring. It has a plurality of rollers. A plurality of flat cam surfaces are provided on the outer peripheral surface of the inner ring in the circumferential direction, and rollers are disposed in a wedge-shaped space between the cam surface and the inner peripheral surface of the outer ring.

  In this one-way clutch, when the rotational speed of the pulley is relatively higher than the rotational speed of the rotating shaft, the roller rolls to the narrow side of the wedge-shaped space and meshes with the cam surface and the inner peripheral surface of the outer ring. A pulley and a rotating shaft are integrated, and both are rotated synchronously. Further, when the rotational speed of the pulley is relatively smaller than the rotational speed of the rotating shaft, the roller rolls to the wide side of the wedge-shaped space, so that the engagement of the roller with the cam surface and the inner peripheral surface of the outer ring is released, and the pulley The power transmission from to the rotating shaft is cut off.

  In addition, the one-way clutch described in Patent Document 1 has torque limiter means. Specifically, the torque limiter means is configured by providing a recess for inserting and holding the roller adjacent to the narrow end of the wedge-shaped space on the cam surface. For example, when the rotational torque (load torque) of the rotating shaft increases due to the seizure of the compressor, the roller rolls to the narrow side of the wedge-shaped space and further falls into the recess. Thereby, a roller leaves | separates from the internal peripheral surface of an outer ring | wheel, and the power transmission from a pulley to a rotating shaft is interrupted | blocked.

JP 2002-106608 A

  The torque limiter means provided in the one-way clutch described in Patent Document 1 is constituted by a concave portion for fitting and holding the roller, and functions when the roller falls into the concave portion. If the means functions, the one-way clutch cannot be used again unless the rollers are artificially removed from the recess and returned to the rust-like space. Therefore, the one-way clutch described in Patent Document 1 is not suitable for applications in which a temporary overload is avoided and the one-way clutch is automatically functioned simultaneously with the elimination of the overload.

  The present invention has been made in view of the above circumstances, and is a one-way that cuts off power transmission when an overload is applied and automatically enables power transmission when the overload is eliminated. The object is to provide a clutch.

  The present invention provides an inner ring, an outer ring having an inner peripheral surface that is concentrically arranged on the radially outer side of the inner ring and that forms a wedge-shaped space between the outer ring and the outer ring, and the wedge-shaped space. And a roller that meshes with the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring on the narrow side of the wedge-shaped space, and a biasing member that biases the roller toward the narrow side of the wedge-shaped space. A one-way clutch, wherein either one of an outer peripheral surface of the inner ring and an inner peripheral surface of the outer ring is engaged with a first cam surface that meshes with the roller, and an end portion on the narrow side of the first cam surface. And a second cam surface that releases the engagement with the roller by expanding a wedge angle in the wedge-shaped space larger than that of the first cam surface. And

  According to the rolling bearing having the above configuration, for example, when the load torque is smaller than a predetermined value, the first cam surface formed on one of the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, and the other The rollers can be meshed with the peripheral surface, and the inner ring and the outer ring can be rotated synchronously. Further, when the load torque increases more than a predetermined value, the rollers can be transferred to the second cam surface adjacent to the first cam surface, and the engagement of the rollers can be released by increasing the wedge angle. That is, the second cam surface can function as a torque limiter means. Even if the torque limiter means by the second cam surface functions, the roller exists in the wedge-shaped space. Therefore, when the load torque becomes smaller than a predetermined value again, the roller is moved to the first cam surface and the other cam surface. The outer ring and the inner ring can be automatically rotated synchronously by meshing with the peripheral surface.

It is preferable that the one-way clutch includes a stopper portion that protrudes in a radial direction from an enlarged end portion of the wedge-shaped space on the first cam surface and restricts movement of the roller.
When the engagement of the rollers is released by the torque limiter function as described above, the rollers may vigorously jump out to the enlarged side of the wedge-shaped space, which places a burden on the biasing member and causes damage to the biasing member. However, by providing the stopper portion as described above, it is possible to restrict the movement of the rollers and reduce the burden on the urging member.

  According to the one-way clutch of the present invention, power transmission can be cut off when an overload is applied, and the power transmission can be automatically enabled when the overload is eliminated.

It is sectional drawing of the one-way clutch which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows a part of one-way clutch. It is a figure explaining the effect | action of the roller in a free state. It is a figure explaining the effect | action of the roller in a locked state. It is a figure explaining the effect | action of a torque limiter means. It is a figure explaining the effect | action of a stopper surface.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a one-way clutch according to an embodiment of the present invention.
The one-way clutch 10 is provided between a driving-side rotating member 18 and a driven-side rotating member 19. In the present embodiment, the driving-side rotating member 18 is a driving shaft, and the driven-side rotating member 19 is a cylindrical driven wheel. Therefore, in the following description, reference numeral 18 is assigned to the drive shaft, and reference numeral 19 is assigned to the driven wheel.

The one-way clutch 10 includes an inner ring 11, an outer ring 12, and a plurality of rollers 13 disposed between the outer peripheral surface 11 a of the inner ring 11 and the inner peripheral surface 12 a of the outer ring 12.
The inner ring 11 is formed in an annular shape. The inner ring 11 is fixed to the drive shaft 18 so as to be integrally rotatable by fitting the inner peripheral surface 11 b to the outer peripheral surface of the drive shaft 18.

  The outer ring 12 is formed in an annular shape having a larger diameter than the inner ring 11. The outer ring 12 is disposed concentrically with the inner ring 11 on the radially outer side of the inner ring 11. The outer ring 12 is fixed to the driven wheel body 19 so as to be integrally rotatable by fitting the outer peripheral surface 12 b to the inner peripheral surface of the driven wheel body 19.

The roller 13 is constituted by a cylindrical roller. The roller 13 is configured to be able to roll on the outer peripheral surface 11 a of the inner ring 11 and the inner peripheral surface 12 a of the outer ring 12.
The same number (eight) of flat first cam surfaces 21 as the rollers 13 are formed on the outer peripheral surface 11a of the inner ring 11, and the inner peripheral surface 12a of the outer ring 12 is formed in a cylindrical surface. A plurality of wedge-shaped spaces S are formed in the circumferential direction between the first cam surface 21 of the inner ring 11 and the inner peripheral surface 12a of the outer ring 12, and the rollers 13 are arranged in the wedge-shaped space S. ing.

  The one-way clutch 10 further includes a cage 14 and an urging member 15. The cage 14 is formed in an annular shape, and holds the plurality of rollers 13 at a predetermined interval along the circumferential direction. The biasing member 15 elastically biases each roller 13 in one direction. The biasing member 15 of the present embodiment is composed of a compression coil spring. The cage 14 is formed with a plurality of pockets 14a for accommodating the rollers 13 in the circumferential direction. Further, the retainer 14 includes a protrusion 14b that guides the biasing member 15 accommodated in the pocket 14a. The urging member 15 urges the rollers 13 in the pocket 14a toward one side in the circumferential direction. Specifically, the roller 13 is urged in the counterclockwise direction of FIG. 1 in a direction (narrow side) in which the wedge-shaped space S is narrowed.

  In the one-way clutch 10 configured as described above, when the rotational speed of the drive shaft 18 exceeds the rotational speed of the driven wheel body 19 due to the drive shaft 18 rotating at an increased speed, the inner ring 11 becomes the outer ring 12. In contrast, an attempt is made to make a relative rotation in one direction A (counterclockwise direction in FIG. 1). In this case, due to the urging force of the urging member 15, the roller 13 slightly moves in the direction in which the wedge-shaped space S is narrowed (counterclockwise direction in FIG. 1), and the outer peripheral surface of the roller 13 is the first of the inner ring 11. The cam surface 21 and the inner peripheral surface 12a of the outer ring 12 are pressed against each other, and the roller 13 is engaged with the first cam surface 21 and the inner peripheral surface 12a of the outer ring 12 (locked state). As a result, the inner ring 11 and the outer ring 12 are connected and can rotate integrally in the one direction A, and the drive shaft 18 and the driven wheel body 19 can be rotated synchronously in the one direction A.

  Further, when the drive shaft 18 is rotated at a constant speed after the accelerated rotation and the rotation speed of the drive shaft 18 is the same as the rotation speed of the driven wheel body 19, the rollers 13 are engaged with the inner ring 11 and the outer ring 12. Held in a state. For this reason, the one-way clutch 10 maintains the integral rotation of the inner ring 11 and the outer ring 12 in the one direction, and the drive shaft 18 and the driven wheel body 19 continue to rotate synchronously.

  On the other hand, when the rotational speed of the drive shaft 18 is lower than the rotational speed of the driven wheel body 19 due to the rotation of the drive shaft 18 being decelerated, the inner ring 11 moves in the other direction (the clockwise direction in FIG. 1). ) Try to rotate relative to. In this case, the rollers 13 move in the direction (enlargement side) in which the wedge-shaped space S is widened against the urging force of the urging member 15, so that the rollers 13 are engaged with the inner ring 11 and the outer ring 12. It becomes a released state (free state). In this way, the engagement between the rollers 13 is released, so that the connection between the drive shaft 18 and the driven wheel body 19 is cut off.

  The one-way clutch 10 of the present embodiment has torque limiter means. The torque limiter means that the rotational speed of the drive shaft 18 is the rotational speed of the driven wheel body 19 when the rotational torque of the driven wheel body 19 (torque for rotating the driven wheel body 19; load torque) is larger than a predetermined value. Even if it exceeds the upper limit, the connection between the drive shaft 18 and the driven wheel body 19 is cut off.

FIG. 2 is an enlarged cross-sectional view showing a part of the one-way clutch 10.
As shown in FIG. 2, in addition to the first cam surface 21, a second cam surface 22 and a stopper surface (stopper portion) 23 are provided on the outer periphery of the inner ring 11.
The second cam surface 22 constitutes the aforementioned torque limiter means. The second cam surface 22 is provided adjacent to the narrow side end of the wedge-shaped space S in the first cam surface 21. The second cam surface 22 is formed as a flat surface that rises (protrudes) radially outward from the end of the first cam surface 21. A first cam surface 21 and the second cam surface 22 intersects at an angle theta _1.

The stopper surface 23 is provided adjacent to the end portion on the enlarged side of the wedge-shaped space S in the first cam surface 21. The stopper surface 23 is formed as a flat surface that rises (protrudes) radially outward from the end of the first cam surface 21. Stopper surface 23 and the first cam surface 21 intersects at an angle theta _2. The stopper surface 23 restricts the movement of the roller 13 toward the enlargement side of the wedge-shaped space S. Specifically, the circumferential position is set so that the roller 13 does not contact the cage 14 (particularly the protrusion 14b) and the urging member 15 is not compressed to the minimum length (contact length). ing. The angle θ ₂ between the stopper surface 23 and the first cam surface 21 is not particularly limited as long as the movement of the roller 13 can be restricted at a predetermined position.

  The outer peripheral surface of the inner ring 11 is recessed inward in the radial direction by forming the first cam surface 21, the second cam surface 22, and the stopper surface 23. In other words, the first cam surface 21, the second cam surface 22, and the stopper surface 23 are formed by forming the recess 24 on the outer peripheral surface of the inner ring 11. The roller 13 is disposed in the recess 24.

Hereinafter, the operation of the first cam surface 21, the second cam surface 22, and the stopper surface 23 will be specifically described.
FIG. 3 is a diagram for explaining the operation of the roller 13 in the free state. In this case, the roller 13 is on the first cam surface 21 and is not in contact with the inner peripheral surface 12 a of the outer ring 12. Further, the roller 13 is not in contact with the second cam surface 22 and the stopper surface 23.

  FIG. 4 is a diagram for explaining the operation of the roller 13 in the locked state. In this case, the rotation of the inner ring 11 in the direction of arrow A causes the roller 13 to move in the same direction by the urging force of the urging member 15, and meshes with the first cam surface 21 and the inner peripheral surface 12 a of the outer ring 12. As a result, the outer ring 12 also rotates in the direction of arrow A in synchronization with the inner ring 11.

  The roller 13 receives a compressive force along a line L1 connecting the contact P1 with the inner peripheral surface 12a of the outer ring 12 and the contact P2 with the first cam surface 21. FIG. 4 particularly shows the compressive force F from the inner peripheral surface 12 a of the outer ring 12. A tangential direction component Ft of the inner peripheral surface 12a in the compression force F is applied to the outer ring 12 as a driving force.

On the other hand, a frictional force f is generated between the roller 13 and the inner peripheral surface 12 a of the outer ring 12. The frictional force f has a maximum value (ie, f = μFn) obtained by multiplying the vertical component Fn of the compressive force F with respect to the inner peripheral surface 12a by the static friction coefficient μ. The angle α between the compressive force F and the vertical component Fn is ½ of the wedge angle θ ₃ between the first cam surface 21 and the inner peripheral surface 12a of the outer ring 12 (α = θ _3/2 ).

  When the roller 13 is in contact with the first cam surface 21, the angle α is smaller than a friction angle that causes a relative slip between the roller 13 and the inner peripheral surface 12 a of the outer ring 12. Therefore, the driving force Ft and the frictional force f are balanced, and the roller 13 is engaged with the inner peripheral surface 12a of the outer ring 12. The relationship between the roller 13 and the first cam surface 21 is the same, and the roller 13 is engaged with the first cam surface 21. Therefore, the outer ring 12 rotates integrally with the inner ring 11 in the arrow A direction. In general, there is a relationship of μ = tan β between the friction angle β and the static friction coefficient μ.

FIG. 5 is a diagram for explaining the operation of the torque limiter means.
When the rotational torque of the outer ring 12 increases, the roller 13 moves toward a narrower region of the wedge-shaped space S, and when the torque reaches the predetermined rotational torque at which the torque limiter means operates, the roller 13 moves from the first cam surface 21. Transition to the second cam surface 22. At this time, the roller 13 receives a compressive force along a line segment L2 connecting the contact P3 with the inner peripheral surface 12a of the outer ring 12 and the contact P4 with the second cam surface 22. FIG. 5 particularly shows the compressive force F from the inner peripheral surface 12 a of the outer ring 12.

The wedge angle θ ₄ between the second cam surface 22 and the inner peripheral surface 12a of the outer ring 12 is based on the wedge angle θ ₃ between the first cam surface 21 and the inner peripheral surface 12a of the outer ring 12 (see FIG. 4). Is also big. Furthermore, the angle _{α '(= θ 4/2} ) between the compression force F and its vertical component Fn is friction angle causing relative sliding between the inner peripheral surface 12a of the roller 13 and the outer ring 12 Bigger than. Therefore, the driving force Ft is larger than the maximum static friction force f ′. As a result, the outer ring 12 slips in the direction of the driving force Ft relative to the roller 13, and the engagement between the roller 13 and the outer ring 12 is released. Therefore, the connection between the inner ring 11 and the outer ring 12 is cut off, and the inner ring 11 and the outer ring 12 rotate relative to each other.

  As described above, the second cam surface 22 is provided adjacent to the first cam surface 21, and the roller 13 is moved from the first cam surface 21 to the second cam surface 22 when the rotational torque of the outer ring 12 is not less than a predetermined value. By shifting to, the wedge angle of the wedge-shaped space S sandwiching the roller 13 can be rapidly expanded, and the engagement of the roller 13 with the inner ring 11 and the outer ring 12 can be released.

  The rotational torque (limit value) for releasing the engagement between the roller 13 and the inner ring 11 and the outer ring 12 can be set according to the circumferential position of the second cam surface 22 (position where the roller 13 contacts). In addition, by appropriately setting the circumferential position of the second cam surface 22 for the plurality of rollers 13, it is possible to prevent variations in the operation timing of the torque limiter means, and a stable torque limiter function. Can be realized.

  In addition, even if the engagement between the inner ring 11 and the outer ring 12 is released, the roller 13 exists in the wedge-shaped space S just by returning to the enlargement side of the wedge-shaped space S. Therefore, the rotational torque of the outer ring 12 is a limit value. If it falls below, the one-way clutch 10 can be made to function automatically again.

FIG. 6 is a diagram for explaining the operation of the stopper surface 23.
As described with reference to FIG. 5, when the engagement between the roller 13 and the outer ring 12 is released by the second cam surface 22, the roller 13 has the second cam surface 22 and the inner peripheral surface 12 a of the outer ring 12. And then jump out toward the expansion side (in the direction of arrow C) of the wedge-shaped space S. As a result, the roller 13 strongly pushes back the urging member 15 to compress it.

  However, if the urging member 15 is strongly compressed by the roller 13 every time the rotational torque of the outer ring 12 reaches the limit value, the urging member 15 may deteriorate early and the life may be shortened. For this reason, in this embodiment, the stopper surface 23 is formed on the inner ring 11, and the compression of the biasing member 15 is suppressed by restricting the movement of the rollers 13 by the stopper surface 23. With such a configuration, the life of the urging member 15 can be increased.

The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope of the invention described in the claims.
For example, in the above embodiment, the first cam surface, the second cam surface, and the stopper surface are formed on the inner ring, but these may be formed on the outer ring. In this case, the outer peripheral surface of the inner ring is formed in a cylindrical shape.

Moreover, in the said embodiment, although the rotation member on the drive side was formed in the shaft shape, and the rotation member on the driven side was formed in the cylindrical shape, the reverse may be sufficient. Further, the outer ring may be disposed on the driving side, and the inner ring may be disposed on the driven side.
In the above embodiment, the boundary between the first cam surface and the second cam surface is an angular shape, but the boundary may be formed in a smooth curved surface shape.

  The one-way clutch of the present invention can be applied to various uses. For example, it may be applied to a path for transmitting the rotational power of an automobile engine to the rotary shaft of a compressor of an air conditioner, or applied to a path for transmitting the rotational power of a blade in a wind power generator to the rotor shaft of the generator. it can.

10: one-way clutch, 11: inner ring, 11a: outer peripheral surface, 12: outer ring, 12a: inner peripheral surface, 13: roller, 15: biasing member, 21: first cam surface, 22: second cam surface , 23: stopper surface, S: wedge-shaped space

Claims (2)

An inner ring, an outer ring having an inner peripheral surface concentrically arranged on the outer side in the radial direction of the inner ring and forming a wedge-shaped space between the outer ring and the inner ring; and the wedge-shaped and arranged in the wedge-shaped space A one-way clutch comprising a roller that meshes with the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring on the narrow side of the space, and a biasing member that biases the roller toward the narrow side of the wedge-shaped space. There,
Either one of the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring is provided adjacent to the first cam surface with which the rollers are engaged, and the narrow side end of the first cam surface, A one-way clutch, comprising: a second cam surface that releases a mesh with the roller by enlarging a wedge angle in the wedge-shaped space more than the first cam surface.   2. The one-way clutch according to claim 1, further comprising a stopper portion that protrudes in a radial direction from an end portion on the enlarged side of the wedge-shaped space on the first cam surface and restricts movement of the roller.

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