JP2011256929A - One-way clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-way clutch which prevents fatigue rupture due to stress concentration inside a pocket formed in an outer ring to improve durability.SOLUTION: The one-way clutch 10 includes: an inner ring 12; the outer ring 13; a recessed pocket 14 having a cam face 27 formed on the inner circumferential face of this outer ring 13 and also forming a wedge-shaped space 26 between the inner circumferential face of the outer ring 13 and the outer circumferential face of the inner ring 12; and a cylindrical roller 15 stored in the wedge-shaped space 26. Further, the one-way clutch 10 includes an initial stress imposing means which imposes initial stress resisting stress generated inside the pocket 14 by a load that the cam face 27 receives from the cylindrical roller 15 on the predetermined site of the outer ring 13 when the cylindrical roller 15 moves in the narrowing direction of the wedge-shaped space 26.

Description

  The present invention relates to a one-way clutch.

  Vehicles such as automobiles and motorcycles are provided with a starter motor for starting the engine, and a starter clutch is provided between the starter motor and the crankshaft of the engine. The starter clutch is a one-way clutch, and includes an inner ring connected to the output shaft of the starter motor via a speed reduction mechanism, an outer ring connected to the crankshaft, and rollers disposed between the outer ring and the inner ring. ing. When the output shaft of the starter motor rotates in one direction, the rollers engage with each other between the outer ring and the inner ring, so that the inner ring and the outer ring rotate together, and the rotational power of the starter motor is transmitted to the crankshaft. When the starter motor is stopped after the engine is started, the output shaft of the starter motor rotates in the other direction relative to the crankshaft, and the roller engagement between the outer ring and the inner ring is released. Power transmission between the two is cut off.

  As the one-way clutch as described above, a plurality of pockets are formed on the inner peripheral surface of the outer ring at intervals in the circumferential direction, and rollers and springs are accommodated in the pockets (for example, Patent Documents). 1). The bottom surface of the pocket is provided with a cam surface that forms a wedge-shaped space with the outer peripheral surface of the inner ring, and the rollers are disposed between the cam surface and the outer peripheral surface of the inner ring. The spring is arranged so as to bias the rolling element in a direction in which a gap between the cam surface and the outer peripheral surface of the inner ring is reduced (a narrow direction of the wedge-shaped space).

JP 2007-285471 A

In FIG. 5, the principal part of the conventional one-way clutch is enlarged and shown. In the pocket 114 formed in the outer ring 132, one side (left side in the figure) in the circumferential direction is a roller accommodating part 122, and the other side (right side in the figure) is a spring accommodating part 123. A side surface of the spring accommodating portion 123 is a spring receiving surface 129 that receives one end of the spring, and a boundary point P between the spring receiving surface 129 and the bottom surface of the spring accommodating portion 123 is a round shape having a relatively small diameter. Yes.
On the other hand, when the inner ring 131 rotates in the direction indicated by the arrow X and the roller 115 is caught between the cam surface 127 and the inner ring 131, a force F ₁ directed radially outward acts on the cam surface 127, this force F _1, tensile stress is generated concentrated in particularly large boundary point P of the shape change. And when such a tensile stress acts repeatedly over a long period of time, there is a problem that the possibility of fatigue failure starting from the boundary point P increases.

  In order to suppress such fatigue failure, it is conceivable to increase the outer diameter of the outer ring 132 to increase the rigidity. However, in this case, the one-way clutch is enlarged, and a wide mounting space is required. In automobiles and motorcycles, the size of the one-way clutch is not preferable because the arrangement space for the engine and its accessories is large.

  The present invention has been made in view of such circumstances, and provides a one-way clutch that prevents fatigue failure due to stress concentration in a pocket formed in an outer rotating body and improves durability. Objective.

(1) Between the inner rotator, the annular outer rotator disposed on the radially outer side of the inner rotator, and the outer peripheral surface of the inner rotator formed on the inner peripheral surface of the outer rotator. A concave pocket having a cam surface forming a wedge-shaped space, and a rolling element housed in the wedge-shaped space of the pocket, and one of the inner rotating body and the outer rotating body. The one rotating body and the other rotating body are locked so as to be integrally rotatable by moving the rolling element in the narrow direction of the wedge-shaped space by rotation in one direction relative to the other rotating body by By the rotation of the one rotating body in the other direction relative to the other rotating body, the rolling element is moved in the expanding direction of the wedge-shaped space to lock the one rotating body and the other rotating body. Release the one-way In,
A prestress that imparts to the outer rotating body a prestress against the stress generated in the pocket by the load that the cam surface receives from the rolling element when the rolling element moves in the narrow direction of the wedge-shaped space. It is provided with the provision means.

  With such a configuration, the stress generated in the pocket by the load applied from the rolling element to the cam surface can be relaxed by the prestress applied to the outer rotating body in advance. Therefore, fatigue failure of the outer rotating body due to long-term use of the one-way clutch can be prevented, and durability of the one-way clutch can be improved.

(2) It is preferable that the said prestress provision means consists of a press means which presses the radial direction outer side of the formation part of the said pocket in the said outer side rotary body to radial direction inward.
With such a configuration, a stress generated in the outer rotating body by a load applied from the rolling element to the cam surface, particularly a compressive stress against the tensile stress can be applied as a prestress.

(3) The outer rotating body includes a first annular member having an inner peripheral surface in which the pocket is formed, and a second annular member having an inner peripheral surface that fits to the outer peripheral surface of the first annular member. And
The pressing means may partially increase a fitting tightening margin between the outer peripheral surface of the first annular member and the inner peripheral surface of the second annular member at a position in the vicinity of the pocket. .
With such a configuration, it is possible to easily apply prestress to the first annular member in which the pocket is formed only by fitting the first annular member and the second annular member.

(4) The pressing means bulges from a notch portion obtained by partially notching the outer peripheral surface of the first annular member and the inner peripheral surface of the second annular member at a position near the pocket forming portion. , And a bulging portion having a shape adapted to the cutout portion.
With such a configuration, the fitting tightening allowance between the first annular member and the second annular member can be easily partially increased in the vicinity of the pocket forming portion.

(5) The outer rotating body includes a first annular member having an inner peripheral surface on which the pocket is formed, and a second annular member having an inner peripheral surface that is fitted to the outer peripheral surface of the first annular member. And
The pressing means is provided movably in the radial direction on the second annular member, and protrudes from the inner peripheral surface of the second annular member by moving radially inwardly. You may provide the press member which presses an outer peripheral surface.
According to this configuration, the pressing member provided on the second annular member is moved inward in the radial direction, and the outer peripheral surface of the first annular member is pressed by the pressing member, so that the first annular member can be easily formed. Can be prestressed.

(6) The prestress applying means may apply prestress to the rounded portion formed at the circumferential end of the bottom surface of the pocket.
Since stress tends to concentrate on the rounded portion formed at the circumferential end of the bottom surface of the pocket in this way, by applying prestress to this portion, fatigue failure in the portion can be suitably prevented. .

(7) The pocket is formed with the cam surface, and is disposed adjacent to the first accommodating portion for accommodating the rolling element, and the first accommodating portion in the circumferential direction. A second accommodating portion for accommodating an urging member that urges toward the narrow direction of the shape space,
The prestress applying means may apply prestress to a circumferential end portion of the bottom surface on the second housing portion side.
According to this configuration, particularly in the circumferential end portion of the bottom surface of the second accommodating portion disposed at a position away from the cam surface that receives the load from the rolling elements, tensile stress is likely to be generated. By applying the prestress, fatigue failure in the part can be suitably prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the fatigue failure by the stress concentration inside the pocket formed in the internal peripheral surface of an outer side rotary body can be prevented, and the improvement of durability of a one-way clutch can be aimed at.

1 is a cross-sectional view of a one-way clutch according to a first embodiment of the present invention. It is sectional drawing of the outer ring | wheel which expands and shows a pocket formation part. It is sectional drawing of the one way clutch which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the outer ring | wheel which expands and shows a pocket formation part. It is sectional drawing of the principal part of the one-way clutch which concerns on a prior art example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a one-way clutch 10 according to a first embodiment of the present invention.
The one-way clutch 10 of the present embodiment is provided, for example, between a crankshaft of a motorcycle engine and an output shaft of a starter motor, and transmits the rotational power of the starter motor to the crankshaft when the engine is started. After that, power transmission is cut so that rotation of the crankshaft is not transmitted to the output shaft of the starter motor.

  The one-way clutch 10 includes an inner ring (inner rotating body) 12 connected to the output shaft of the starter motor via a gear reduction mechanism or the like so that power can be transmitted, and an outer ring (outer rotating body) 13 connected to the crankshaft of the engine. And have. The one-way clutch 10 has a cylindrical roller 15 as a rolling element housed in a pocket 14 formed in the outer ring 13 and a compression spring 16 as a biasing member.

The inner ring 12 is formed in an annular shape, and a crankshaft is inserted into the central hole 18 via a rolling bearing or the like. The outer peripheral surface of the inner ring 12 is formed in a cylindrical shape.
The outer ring 13 is also formed in an annular shape like the inner ring 12, and its inner peripheral surface is formed in a cylindrical shape and is slidably fitted to the outer peripheral surface of the inner ring 12. The outer peripheral surface of the outer ring 13 is also formed in a cylindrical shape like the inner peripheral surface.

  A plurality of pockets 14 are formed on the inner peripheral surface of the outer ring 13 at intervals in the circumferential direction. In the present embodiment, three pockets 14 are formed at equal intervals in the circumferential direction. Each pocket 14 includes a first accommodating portion 22 for accommodating the cylindrical roller 15 and a second accommodating portion 23 for accommodating the compression spring 16. In addition, the number and arrangement | positioning of the pocket 14 can be changed suitably.

  The first housing portion 22 and the second housing portion 23 are disposed adjacent to each other in the circumferential direction, and the second housing portion 23 is formed shallower than the first housing portion 22. On the bottom surface of the pocket 14, an inclined surface 25 for gradually changing the difference in depth between the first housing portion 22 and the second housing portion 23 is formed at the boundary between the first housing portion 22 and the second housing portion 23.

  The bottom surface of the first accommodating portion 22 is a cam surface 27 that forms a wedge-shaped space 26 between the inner ring 12 and the outer peripheral surface. That is, the cam surface 27 is an inclined surface that approaches the outer peripheral surface of the inner ring 12 toward the front in the left rotation direction (counterclockwise direction) in FIG. 1, and the cylindrical roller 15 accommodated in the first accommodating portion 22. Is engaged between the cam surface 27 and the outer peripheral surface of the inner ring 12 by moving toward the front side in the same direction (narrow direction of the wedge-shaped space 26), and locks the inner ring 12 and the outer ring 13 so as to be integrally rotatable. . Conversely, the cylindrical roller 15 moves to the rear side in the clockwise direction (clockwise direction) (in the direction in which the wedge-shaped space 26 is enlarged), thereby unlocking the inner ring 12 and the outer ring 13.

  The compression spring 16 is composed of a coil spring or a leaf spring, one end of which is in contact with the side surface (spring receiving surface) 29 of the second housing portion 23 of the pocket 14 and the other end is the first housing portion. The cylindrical roller 15 abuts on the cylindrical roller 15 and urges the cylindrical roller 15 in the narrow direction of the wedge-shaped space 26.

  The outer ring 13 includes a first annular member 31 on the radially inner side and a second annular member 32 on the radially outer side. The first annular member 31 has a cylindrical inner peripheral surface 33 and an outer peripheral surface 34, and the pocket 14 is formed in the inner peripheral surface 33. The second annular member 32 has a cylindrical inner peripheral surface 35 and an outer peripheral surface 36, and the inner peripheral surface 35 of the second annular member 32 matches the outer peripheral surface 34 of the first annular member 31. The outer peripheral surface 34 is fitted and fixed to the outer peripheral surface 34.

  A notch 38 is formed in the vicinity of the formation site of the pocket 14 on the outer circumferential surface 34 of the first annular member 31. The cutout portion 38 has a shape in which the outer peripheral surface 34 of the first annular member 31 is cut out in a straight line shape, and the counterclockwise direction (counterclockwise) with respect to the cam surface 27 formed on the bottom surface of the pocket 14. It is formed to be inclined so that the interval is narrow. Further, the notch 38 is formed over a range deviated from the radially outer side of the first accommodating portion 22 of the pocket 14 in the left rotation direction (the opposite side to the second accommodating portion 23), and the second accommodating portion. It is not formed outside 23 in the radial direction.

  On the other hand, a bulging portion 40 having a shape suitable for the notch 38 is formed on the inner peripheral surface 35 of the second annular member 32. That is, the bulging portion 40 is formed in a shape that bulges linearly inward in the radial direction with respect to the inner peripheral surface 35 of the second annular member 32. Then, the second annular member 32 is fitted to the outer peripheral surface 34 of the first annular member 31 in a state where the circumferential position of the bulging portion 40 is aligned with the cutout portion 38 of the first annular member 31. Are combined.

FIG. 2 is a cross-sectional view of the outer ring 13 showing an enlarged pocket forming portion.
A fitting tightening margin between the cutout portion 38 formed in the first annular member 31 and the bulging portion 40 formed in the second annular member 32 is the first annular member 31 and the second annular member 32. It is set larger than the fitting tightening allowance of other parts. Therefore, a compressive force F ₂ directed inward in the radial direction is applied to the pocket forming portion of the first annular member 31, particularly to the radially outer side of the first accommodating portion 22. When such a compressive force F ₂ is applied, the circumferential end of the bottom surface of the pocket 14, particularly the boundary portion P between the spring receiving surface 29 and the bottom surface of the second housing portion 23, is made of compressive stress. Prestress occurs.

  On the other hand, as shown in FIG. 1, when the inner ring 12 rotates in one direction (counterclockwise), the cylindrical roller 15 is caught between the outer peripheral surface of the inner ring 12 and the cam surface 27, and the inner ring 12 and the outer ring 13 are engaged. Is locked to the cam surface 27 in the pocket 14 so that a load directed radially outward from the cylindrical roller 15 is applied to the boundary portion P of the second accommodating portion 23 by the load. Causes tensile stress. However, since the pre-stress consisting of compressive stress is preliminarily applied to the boundary portion P, the tensile stress generated by the load from the cylindrical roller 15 is relaxed. Therefore, even when the tensile stress is repeatedly applied due to long-term use of the one-way clutch 10, fatigue failure can be prevented, and the durability of the one-way clutch 10 can be improved.

Further, the design and manufacturing stage, notch 38 and the relative position and size of the fitting interference by changing and adjusting the direction and magnitude of the compressive force F ₂ between the pockets 14 of the first annular member 31 In addition, the inclination of the cam surface 27 can be finely adjusted.

In addition, when fitting the 1st annular member 31 and the 2nd annular member 32, if the notch part 38 and the bulging part 40 are slightly displaced in the circumferential direction, both fitting tightening margins will be adjusted. can do. Thus, by adjusting the compressive force F ₂ against the pocket forming portion, it becomes possible to appropriately set the magnitude of the prestress. Further, it is possible to finely adjust the inclination of the cam surface 27 by adjusting the degree of circumferential displacement between the notch portion 38 and the bulging portion 40.

FIG. 3 is a cross-sectional view of the one-way clutch 10 according to the second embodiment of the present invention, and FIG. 4 is a cross-sectional view of the outer ring 13 showing an enlarged pocket forming portion.
The outer ring 13 in the one-way clutch 10 of the present embodiment is composed of a first annular member 31 and a second annular member 32 as in the outer ring 13 in the first embodiment. The outer peripheral surface of the second annular member 32 and the inner peripheral surface of the second annular member 32 are not formed with the notch 38 or the bulging portion 40, and both are formed in a cylindrical shape over the entire circumference.

  In the second annular member 32, the same number (three in this embodiment) of female screw holes 44 as the pocket 14 are formed at equal intervals in the circumferential direction, and the female screw holes 44 are formed in the second annular member 32. It penetrates. A set bolt (pressing member) 45 is screwed into the female screw hole 44, and the set bolt 45 can be moved in the radial direction by adjusting the screwing amount of the set bolt 45. When the set bolt 45 is moved inward in the radial direction, the set bolt 45 protrudes from the inner peripheral surface 35 of the second annular member 32, and the outer peripheral surface 34 of the first annular member 31 is radially inward by the set bolt 45. Thus, prestress is applied to the inside of the pocket 14, particularly to the boundary point P of the second housing portion 23.

  In this embodiment, the magnitude of the prestress can be finely adjusted by adjusting the screwing amount of the set bolt 45, and the inclination angle of the cam surface 27 can also be finely adjusted. Furthermore, the pressing location by the set bolt 45 can be adjusted by adjusting the relative position in the circumferential direction of the second annular member 32 with respect to the first annular member 31.

  In the present embodiment, the first and second annular members 31 and 32 are not provided with the notch portion 38 or the bulging portion 40, and the entire outer peripheral surfaces 34 and 36 and inner peripheral surfaces 33 and 35 are cylindrical. Since it can be formed in a shape, the processing is easy, and the processing for forming the female screw hole 44 can also be performed relatively easily.

The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the invention described in the claims.
For example, in the first embodiment (see FIGS. 1 and 2), the shape of the notch 38 formed in the first annular member 31 is not limited to a linear shape, but an arc shape or a mountain shape (two straight lines). The bulging portion 40 of the second annular member 32 may be appropriately formed according to the shape of the cutout portion 38.
Further, the location where the prestress is applied to the inside of the pocket 14 is not limited to the boundary point P of the second accommodating portion 23, but the portion where the largest stress is generated inside the pocket 14 or the most rigid portion. It can be selected from the low part, the most easily damaged part, and the like.

  10: one-way clutch, 12: inner ring (inner rotating body), 13: outer ring (outer rotating body), 14: pocket, 15: cylindrical roller (rolling element), 16: compression spring (biasing member), 22: first 1 accommodating portion, 23: second accommodating portion, 26: wedge-shaped space, 27: cam surface, 29: spring receiving surface, 31: first annular member, 32: second annular member, 38: notch , 40: bulging part, 44: female screw hole, 45: set bolt (pressing member)

Claims (7)

A wedge-like shape is formed between the inner rotator, the annular outer rotator disposed on the radially outer side of the inner rotator, and the outer peripheral surface of the inner rotator. A concave pocket having a cam surface forming a space, and a rolling element housed in the wedge-shaped space of the pocket, the other rotating body of the inner rotating body and the outer rotating body by the other rotating body By rotating in one direction relative to the rotating body, the rolling body is moved in the narrow direction of the wedge-shaped space to lock the one rotating body and the other rotating body so as to be integrally rotatable, By the rotation of the rotating body in the other direction relative to the other rotating body, the rolling element is moved in the expanding direction of the wedge-shaped space to unlock the one rotating body and the other rotating body. To one-way clutch Te,
A prestress that imparts to the outer rotating body a prestress against the stress generated in the pocket by the load that the cam surface receives from the rolling element when the rolling element moves in the narrow direction of the wedge-shaped space. A one-way clutch comprising an applying means.   2. The one-way clutch according to claim 1, wherein the prestress applying means includes pressing means that presses a radially outer side of the pocket forming portion in the outer rotating body radially inward. The outer rotating body includes a first annular member having an inner peripheral surface in which the pocket is formed, and a second annular member having an inner peripheral surface that is fitted to the outer peripheral surface of the first annular member. And
3. The pressing means partially increases a fitting tightening margin between an outer peripheral surface of the first annular member and an inner peripheral surface of the second annular member at a position near the pocket. One-way clutch described in.   The pressing means bulges from a notch part in which an outer peripheral surface of the first annular member is partially cut out and an inner peripheral surface of the second annular member at a position in the vicinity of the pocket forming portion, and the notch The one-way clutch according to claim 3, comprising a bulging portion having a shape adapted to the portion. The outer rotating body includes a first annular member having an inner peripheral surface in which the pocket is formed, and a second annular member having an inner peripheral surface that is fitted to the outer peripheral surface of the first annular member. And
The pressing means is provided so as to be movable in the radial direction with respect to the second annular member, and protrudes from the inner peripheral surface of the second annular member by moving inward in the radial direction. The one way clutch of Claim 2 provided with the press member which presses the outer peripheral surface of a member.   The one-way clutch according to any one of claims 1 to 5, wherein the prestress applying means applies prestress to a rounded portion formed at a circumferential end of the bottom surface of the pocket. The pocket is formed with the cam surface, and is disposed adjacent to the first accommodating portion for accommodating the rolling elements, and the first accommodating portion in the circumferential direction, and the rolling elements are arranged in a wedge-shaped space. A second accommodating portion for accommodating a biasing member that biases toward the narrow direction,
The one-way clutch according to claim 6, wherein the prestress applying means applies prestress to a circumferential end portion of the bottom surface on the second housing portion side.

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