JP2016142325A - Sprag type one-way clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress excessive floating of a sprag when an outer ring idles, and reduce damage such as wear or impression on the sprag and the contact surface of an inner ring.SOLUTION: A sprag type one-way clutch includes: a plurality of sprags 11; a holder 12; and a leaf spring 30 expanding in a tongue manner from the holder 12 toward the sprag 11, and configured to energize the sprag 11 with elasticity. The leaf spring 30 integrally has an energization unit 33 configured to energize the sprag 11 radially outward by being bent in a radial direction, and an inclination regulation unit 33a elastically contacting with the sprag 11 in a circumferential direction when the sprag 11 does not transmit power. The spring constant in the circumferential direction of the inclination regulation unit 33a is larger than the spring constant in the radial direction of the energization unit 33.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sprag type one-way clutch (hereinafter referred to as a one-way clutch) used in a power transmission device such as an automatic transmission of an automobile.

  In an automatic transmission of an automobile, there is known a one-way clutch that is disposed between an inner ring and an outer ring that rotate coaxially and that performs power transmission and shut-off operations (Patent Document 1). As shown in FIG. 6, in the one-way clutch 100, a plurality of sprags 101 are arranged in an annular space sandwiched between an outer ring 104 and an inner ring 105 in the radial direction. The sprags 101 are held at equal intervals in the circumferential direction by the cage 102, are in contact with the outer ring 104 at the point C, and are in contact with the inner ring 105 at the point D. A leaf spring 103 is attached along the inner periphery of the cage 102. The sprag 101 receives a force Fr in the direction shown in FIG. 6 by the leaf spring 103 and is urged clockwise with respect to the point C.

  When the outer ring 104 and the inner ring 105 rotate relatively, the inclination of the sprag 101 changes due to the sliding friction of the contact surface. When the outer ring 104 rotates in the clockwise direction with respect to the inner ring 105, the sprag 101 engages with the inner and outer rings 104, 105 in the radial direction, so that the outer ring 104 and the inner ring 105 rotate integrally. When the outer ring 104 rotates in the counterclockwise direction with respect to the inner ring 105, the sprag 101 is released and the transmission of power is cut off, so that the outer ring 104 rotates idle.

  If the outer ring 104 idles while the sprag 101 and the inner ring 105 are in sliding contact, there is a problem that the contact surface is worn or the rotational torque during idling increases. Therefore, as shown in FIG. 6, when the center of gravity G1 of the sprag 101 is arranged on the right side of the normal line m of the outer ring 104 passing through the contact point C and the centrifugal force is applied, the sprag 101 is located with respect to the point C. Thus, it is biased counterclockwise (Patent Document 2). Thereby, since the sprag 101 floats from the inner ring | wheel 105, abrasion of a contact surface can be reduced. A one-way clutch in which the sprag 101 floats from the inner ring 105 when the outer ring 104 idles is generally referred to as a disengage type one-way clutch.

JP 2003-130089 A Japanese Patent Laid-Open No. 08-219184

Since the conventional one-way clutch 100 is not provided with a mechanism for limiting the amount of lifting (radial displacement) of the sprag 101, when the rotational speed when the outer ring 104 is idling is high, the sprag 101 is disengaged from the inner ring 105. In some cases, the amount of lift was excessive.
If the rotation of the outer ring 104 suddenly stops due to sudden braking of the vehicle or the like when the sprag 101 rises greatly, the speed at which the sprag 101 returns to the position where it comes into contact with the inner ring 105 again increases. As a result, the sprag 101 and the inner ring 105 collide violently, and damage such as wear and indentation occurs on the contact surfaces of the sprag 101 and the inner ring 105.

  In order to prevent this damage, for example, the clearance between the sprag 101 and the retainer 102 (for example, the distance between the sprag 101 and the portion E of the retainer 102) is reduced to suppress the floating amount of the sprag 101. And a method of suppressing the lifting of the sprag 101 by increasing the spring force Fr of the leaf spring 103. However, the former method has a problem that workability when assembling the sprag 101 is deteriorated. In the latter method, the force that the sprag 101 and the inner and outer rings 104 and 105 come into contact with each other increases. There is a problem of increasing wear. Thus, in the disengagement type sprag type one-way clutch, it was impossible to prevent wear and indentation caused by contact with the inner ring 105 after the sprag lifted up.

  An object of the present invention is to reduce damage such as wear and indentation on the contact surface of the sprag and the inner ring by suppressing excessive lift of the sprag when the outer ring idles in a disengagement type sprag type one-way clutch. It is.

  A sprag type one-way clutch according to an embodiment of the present invention includes a plurality of sprags that are incorporated in an annular space sandwiched in a radial direction between an inner ring and an outer ring that rotate relatively, and transmit or cut power, and the sprags. A retainer that holds the sprags at a predetermined interval in the circumferential direction, and a leaf spring that extends in a tongue shape from the retainer toward the sprags and elastically biases the sprags. An urging portion that bends and urges the sprag radially outward and an inclination restricting portion that elastically contacts the sprag in the circumferential direction when the sprag does not transmit power are integrally provided.

  According to the present invention, in a disengagement-type sprag type one-way clutch, it is possible to suppress excessive sprag lift when the outer ring rotates idly and reduce damage such as wear and indentation on the contact surface of the sprag and the inner ring. I can do it.

It is a side view of the one way clutch which is an embodiment of the present invention. It is a front view of the ribbon spring of this embodiment. It is a fragmentary sectional view in XX of FIG. It is a state figure explaining the positional relationship of a sprag and a leaf | plate spring. It is a conceptual diagram explaining the attitude | position of a sprag when a centrifugal force acts. It is a side view which shows the structure of the conventional one-way clutch.

  An embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the drawings. FIG. 1 is a partial side view of a one-way clutch 10 of the present embodiment. Although only a part is shown, the configuration of the part not shown is the same, and is connected in an annular shape as a whole. In the following description with reference to FIG. 1, the vertical direction in FIG. The direction orthogonal to the paper surface is called the axial direction.

  A one-way clutch 10 in FIG. 1 is incorporated in an annular space K formed between an inner ring 14 and an outer ring 15, and includes a plurality of sprags 11 arranged at equal intervals in the circumferential direction, a retainer 12, And a ribbon spring 13.

  The outer ring 15 and the inner ring 14 are made of metal and are made of alloy steel for machine structure. The inner peripheral surface of the outer ring 15 is subjected to quench hardening and then ground into a cylindrical shape. The outer peripheral surface of the inner ring 14 is subjected to quench hardening and then ground into a cylindrical shape.

  The sprag 11 is made of metal and is made of bearing steel or the like. The shape is columnar, and the cross-sectional shape parallel to the paper surface is uniform in the axial direction. The sprag 11 has an outer ring engagement surface 16 that is a radially upward convex arc in a cross section parallel to the paper surface, and an inner ring engagement surface 17 that is a radially downward convex arc. The outer ring engagement surface 16 and the inner ring engagement surface 17 are connected to each other in the radial direction by the side surfaces 20a and 20b. In the sprag 11 shown in FIG. 1, a spring receiving portion 19 protruding in the circumferential direction is formed on the side surface 20a on the left side in the circumferential direction in the drawing. As shown in FIG. 4, the spring receiving portion 19 is formed by a spring receiving surface 19a extending in a substantially circumferential direction and an inclined surface 19b extending in a substantially radial direction, and the spring receiving surface 19a and the inclined surface are formed. 19b is connected to each other on the R plane. The spring receiving surface 19a is in contact with the leaf spring 30 of the ribbon spring 13 and receives a force Fr.

  The cage 12 has a thin, substantially cylindrical shape, is made of metal or reinforced resin, and is incorporated in the annular space K coaxially with the outer ring 15 and the inner ring 14. The cage 12 is provided with a plurality of pockets 18 penetrating in the radial direction at equal intervals in the circumferential direction. The shape of each pocket 18 viewed from the radial direction is substantially rectangular (not shown), and one sprag 11 is fitted in each pocket 18.

  The ribbon spring 13 is incorporated along the inner periphery of the cage 12. FIG. 2 is a front view of the ribbon spring 13 in a free state before being incorporated into the one-way clutch 10. When incorporated into the one-way clutch 10, both ends thereof are bent in the direction perpendicular to the paper surface and rounded so that both ends overlap each other. FIG. 3 is a partial cross-sectional view of the XX cross section of FIG. 2 viewed in the direction of the arrow. In the following description, with respect to the ribbon spring 13 in FIG. 2, the longitudinal direction (the left-right direction in the figure) is referred to as “circumferential direction”, and the direction parallel to the paper surface and orthogonal to the circumferential direction is referred to as “axial direction”.

The ribbon spring 13 is formed by stamping a rolled steel strip for a spring into a ribbon shape with a die and then pressing it in the thickness direction. The ribbon spring 13 has a pair of annular portions 20 and 20 extending in parallel to each other in the circumferential direction, and the pair of annular portions 20 and 20 are a plurality of circumferentially arranged plural intervals. The bridge portions 21 are connected to each other in the axial direction. In the annular portion 20, bent portions 24 (see FIG. 3) projecting in a substantially V shape on the back side in the direction perpendicular to the paper surface are formed at equal intervals. A leaf spring 30 extending in the circumferential direction is integrally formed at substantially the center in the axial direction of the bridging portion 21.
Thus, as shown in FIG. 2, the ribbon spring 13 is formed with window holes 23 having a substantially U shape and penetrating in a direction perpendicular to the paper surface at regular intervals in the circumferential direction. The bridging portion 21 is provided with holes 22 for weight reduction.

  The window hole 23 of the ribbon spring 13 is combined so as to match the phase of the pocket 18 formed in the cage 12. Therefore, a sprag insertion hole 18a that penetrates in the radial direction through the cage 12 and the ribbon spring 13 is secured, and the sprag 11 is inserted into the sprag insertion hole 18a. Since the leaf spring 30 protrudes into the sprag insertion hole 18a, when the sprag 11 is assembled, the leaf spring 30 is pushed inward in the radial direction and inserted from the radially outward side.

As shown in FIG. 3, the plate spring 30 is equivalent to the plate thickness of the rolled steel strip for springs, and has a uniform plate thickness in the circumferential direction. Further, the width dimension of the leaf spring 30 (the dimension in the axial direction of the ribbon spring 13) is uniform in the circumferential direction.
A biasing portion 33 extending substantially in the circumferential direction is formed at the circumferential tip of the leaf spring 30. When the sprag 11 is incorporated into the sprag insertion hole 18a, the urging portion 33 and the spring receiving surface 19a abut on each other in a substantially radial direction. On the side close to the base of the leaf spring 30 connected to the urging portion 33, an inclination restricting portion 33a extending in a substantially radial direction is formed. The inclination restricting portion 33a is slightly inclined in a direction away from the urging portion 33 as it goes outward in the radial direction.

  FIG. 4 is a state diagram illustrating the positional relationship between the sprag 11 and the leaf spring 30 when the sprag 11 is incorporated. When the sprag 11 is incorporated, the urging portion 33 of the leaf spring 30 is pushed by the sprag 11 and elastically bends radially inward (downward in the drawing). The shapes of the urging portion 33 and the inclination regulating portion 33a are substantially the same as the shape of the spring receiving surface 19a and the inclined surface 19b of the sprag 11 in FIG. At the same time as the portion 33 comes into contact with the spring receiving surface 19a, the inclination regulating portion 33a comes close to the inclined surface 19b. At this time, the inclination restricting portion 33a and the inclined surface 19b are in contact with each other or face each other in the circumferential direction with a slight clearance Δs.

  In FIG. 3, the portion sandwiched in the circumferential direction between the inclination regulating portion 33 a and the bridging portion 21 of the leaf spring 30 is a deflection adjusting portion 32. In the deflection adjusting unit 32, the actual length in the circumferential direction of the leaf spring 30 is changed by bending the leaf spring 30 in the radial direction. By increasing or decreasing the actual length in the circumferential direction, the spring constant when the leaf spring 30 is bent can be adjusted.

  The operation of the sprag 11 when the inner and outer rings 14 and 15 rotate will be described with reference to FIG. In addition, since the inner peripheral surface of the outer ring 15 and the outer ring engaging surface 16 and the outer peripheral surface of the inner ring 14 and the inner ring engaging surface 17 are respectively arcuate surfaces, they are in contact with each other by “lines”. In the description according to 4, the contact portion is expressed as a “contact point”. A point where the outer ring 15 and the outer ring engaging surface 16 come into contact is referred to as a contact point P, and a point where the inner ring 14 and the inner ring engaging surface 17 come into contact is referred to as a contact point Q.

The case where the outer ring 15 rotates in the clockwise direction relative to the inner ring 14 and the sprag 11 meshes with the inner and outer rings 14 and 15 in the radial direction (hereinafter referred to as “when locked”) will be described.
A force Fr is applied to the sprag 11 by a leaf spring 30. As shown in FIG. 4, the direction of the line of action of the force Fr is toward the left side in the circumferential direction from the contact point P, so that the sprag 11 is biased in the clockwise direction with respect to the contact point P. At the same time, the posture of the sprag 11 is maintained by contacting the inner ring 14 at the contact point Q.
At the time of locking, the sprag 11 is dragged in the circumferential direction rightward at the contact point P, and is dragged in the circumferential direction leftward at the contact point Q. Since the distance between the contact points P and Q is larger than the radial dimension between the inner and outer rings 14, 15, the sprags 11 are engaged in the radial direction, and the inner ring 14 and the outer ring 15 rotate together.

When the outer ring 15 rotates counterclockwise relative to the inner ring 14 and the outer ring 15 idles (hereinafter referred to as “idling”), the sprag 11 is dragged leftward in the circumferential direction at the contact point P. Thus, the contact point Q is dragged to the right in the circumferential direction. Since the force acting on the contact points P and Q is in a direction that relaxes the engagement of the sprags 11 in the radial direction, the outer ring 15 idles with respect to the inner ring 14.
When the outer ring 15 is rotating, centrifugal force is acting on the sprag 11. When the sprag 11 of this embodiment is incorporated in the annular space K between the inner and outer rings 14 and 15, the position of the center of gravity is positioned on the right side in the circumferential direction with respect to the normal line n passing through the contact point P. The shape is set. The position of the center of gravity is indicated by a point G2 in FIG. As a result, when the centrifugal force acts, the sprag 11 is urged in the counterclockwise direction with respect to the contact point P.
When the rotational speed of the outer ring 15 is large, the counterclockwise moment at the contact point P due to the centrifugal force is larger than the clockwise moment due to the force Fr, so that the sprag 11 is lifted from the inner ring 14.

  4 and 5, the effect of the leaf spring 30 suppressing the lifting amount when the sprag 11 is lifted will be described in detail. FIG. 5 is a conceptual diagram for explaining the posture of the sprag 11 when it is lifted by the action of centrifugal force. In FIG. 5, the posture of the sprag before being lifted by the centrifugal force is indicated by a broken line. For convenience of explanation, in FIG. 5, the inclination amount of the sprag 11 is shown exaggerated from the actual inclination amount.

  As shown in FIG. 4, the posture before and after the sprag 11 is lifted from the inner ring 14 will be described with the inclination of the inclined surface 19 b with respect to the normal n as “inclination angle θ”.

  The inclination angle θ when the sprag 11 is lifted from the inner ring 14 is defined as θ1 (see FIG. 5), and is in a state before being lifted (a state where the inner and outer rings 14 and 15 are in contact at the contact point P and the contact point Q). When the contact angle θ is θo (see FIG. 4), θ1 is larger than θo. Since the inclination restricting portion 33a and the inclined surface 19b are close to each other, when the inclination angle θ of the sprag 11 increases in this manner, the inclined surface 19b and the inclination restricting portion are at the position indicated by the arrow A in FIG. 33a immediately contacts.

Since the inclined surface 19b of the sprag 11 and the inclination regulating portion 33a are opposed to each other in the circumferential direction, the force Fa acts in the circumferential direction when the contact portion is brought into contact, and the direction in which the force Fa acts on the leaf spring 30 in its longitudinal direction The direction of compression. The leaf spring can be easily bent when a load is applied in a direction perpendicular to the longitudinal direction thereof, but has a high rigidity and cannot be easily bent when a load is applied in the longitudinal direction. Therefore, when the force Fa is applied, the spring constant when the inclination restricting portion 33a bends in the circumferential direction increases.
As a result, when the rotational speed of the outer ring 15 increases and the centrifugal force increases and the sprag 11 comes into contact with the inclination restricting portion 33a, the amount of bending in the circumferential direction of the inclination restricting portion 33a is small. It is possible to prevent the inclination angle θ from increasing.

In order to explain the effect of the leaf spring 30 of the present embodiment preventing the sprags 11 from lifting, the behavior of the sprag 101 when using the conventional leaf spring 103 will be described as a comparative example (see FIG. 6).
The conventional leaf spring 103 is not provided with an inclination restricting portion adjacent to the sprag 101. Therefore, when the centrifugal force acts on the sprag 101 and the amount of inclination (the amount of inclination represented by the inclination angle θ in FIG. 4) increases, the spring receiving portion 106 of the sprag 101 causes the leaf spring 103 to move in the radial direction. The force Fr only increased. However, the leaf spring 103 can be easily bent in a direction perpendicular to the longitudinal direction, and the spring constant in the direction in which the force Fr acts is small. For this reason, even if the amount of inclination of the sprag 101 increases, the force Fr hardly increases. As a result, an increase in the amount of inclination of the sprag 101 cannot be suppressed, so that the sprag 101 cannot be prevented from rising excessively.

  On the other hand, in this embodiment, since the sprag 11 can be supported with high rigidity by supporting it in the circumferential direction, an increase in inclination is suppressed when trying to float, and the sprag 11 can be lifted excessively. Can be suppressed.

Further, it is desirable to make the amount of lifting of the sprags 11 as small as possible. By doing so, it is possible to suppress an increase in speed when the sprag 11 returns to the position where it comes into contact with the inner ring 14 again, and it is possible to suppress damage such as wear and indentation on the contact surface of the sprag 11 and the inner ring 14. . In addition, a very small lifting amount is sufficient to prevent the sliding contact surface from being worn due to idling while the inner ring 14 and the sprag 11 are in sliding contact.
In the one-way clutch 10 of the present embodiment, before the sprag 11 is lifted, the inclined surface 19b and the tilt restricting portion 33a are assembled close to each other, so that when the sprag 11 is about to float, immediately The inclination of the sprag 11 can be suppressed by abutting against the inclination restricting portion 33a. Therefore, the amount of the sprag 11 that floats from the outer peripheral surface of the inner ring 14 can be reduced.

  As a result, after the outer ring 15 is idled and the sprag 11 is lifted from the inner ring 14, the rotational speed is suddenly reduced, or the outer ring 15 stops rotating, so that the sprag 11 comes into contact with the outer ring 15 and the inner ring 14 again. Even in this case, since the amount of movement of the sprag 11 is small, the impact at the time of contact can be greatly reduced. Therefore, damage such as wear and indentation on the contact surfaces of the sprag 11 and the inner ring 14 can be reduced.

Further, the inclination restricting portion 33a is formed integrally with the leaf spring 30, and can be formed simultaneously with the urging portion 33 when the ribbon spring is press-molded. Therefore, it is not necessary to add a new part in order to suppress the inclination of the sprag, and the cost does not increase.
Further, the biasing portion 33 for applying a load to the sprag 11 and the tilt regulating portion 33a for suppressing the tilt of the sprag 11 are integrally formed, so that the relative position between the tilt regulating portion 33a and the biasing portion 33 is formed. Can be manufactured with high accuracy. Therefore, when the urging portion 33 of the leaf spring 30 and the spring receiving surface 19a of the sprag 11 come into contact with each other when the sprag 11 is assembled, the inclination regulating portion 33a and the inclined surface 19b of the sprag inevitably come close to each other. As a result, when the sprag 11 is about to rise, the sprag 11 immediately comes into contact with the inclination regulating portion 33a of the leaf spring 30, so that excessive lifting can be reliably prevented.

  As described above, in the one-way clutch 10 of the present embodiment, the amount of lifting of the sprag 11 when the outer ring 15 idles can be reduced. Therefore, even when the sprag 11 is re-engaged with the outer ring 15 and the inner ring 14 when the rotation speed is drastically decreased or the outer ring 15 stops rotating after the outer ring 15 is idling, the movement amount of the sprag 11 is reduced. I can do it. As a result, the impact upon contact can be greatly reduced, so that the occurrence of indentations and wear on the rolling surface of the inner ring 14 and the inner ring engaging surface 17 of the sprag 11 can be reduced.

10: one-way clutch, 11: sprag, 12: cage, 13: ribbon spring,
14: inner ring, 15: outer ring, 16: outer ring engaging surface, 17: inner ring engaging surface, 18: pocket,
19: spring receiving portion, 19a: spring receiving surface, 19b: inclined surface, 20: annular portion, 21: bridging portion, 23: window hole, 30: leaf spring, 33: biasing portion, 33a: inclination regulating portion, 100: One-way clutch, 101: Sprag, 102: Cage, 103: Leaf spring, 104: Outer ring, 105: Inner ring, 106: Spring receiving part

Claims (2)

A plurality of sprags that are incorporated in an annular space sandwiched in the radial direction between the inner ring and the outer ring that rotate relatively, and transmit or block power;
A retainer for retaining the sprags at predetermined intervals in the circumferential direction;
A leaf spring extending in a tongue shape from the cage toward the sprag and elastically urging the sprag.
The leaf spring is
A biasing portion that flexes in the radial direction and biases the sprag radially outward, and an inclination regulating portion that elastically contacts the sprag in the circumferential direction when the sprag does not transmit power.
Sprag type one-way clutch. The circumferential spring constant of the tilt restricting portion is larger than the radial spring constant of the biasing portion,
The sprag type one-way clutch according to claim 1.

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