JPH11270596A - One-way clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the maximum allowable capacity of the power transmission torque without increasing the contour dimensions in a one-way clutch. SOLUTION: In a one-way clutch A to switch two concentrically arranged inner and outer annular bodies 1, 2 in a locked condition of synchronous rotation and in a free condition of relative rotation, a cam surface 1a comprising a flat surface or a cicumferentially bend recessed surface is formed at several parts on the circumference of the outer circumferential surface of the inner annular body 1. The contact condition of a rolling element 4 with the cam surface 1a forms the contact of a cylindrical surface with the flat surface or the recessed surface, and the contact area of the cam surface 1a with the roller 4 is increase more than the conventional value compared with the contact mode of conventional two cylinders. The contact surface pressure of the roller 4 with the cam surface 1a can be reduced, and the maximum allowable capacity of the power transmission torque is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a one-way clutch. The one-way clutch is built in a feed mechanism of various functional devices, a pulley mounted on an auxiliary machine driven via a belt from a crankshaft of an engine of an automobile or the like, and the like. Examples of the aforementioned auxiliary equipment include a compressor for an air conditioner of an automobile, a water pump, an alternator, a cooling fan, a crank pulley, and the like.

[0002]

2. Description of the Related Art A one-way clutch switches between a locked state in which rotational power is transmitted from one of two inner and outer rings to the other, and a free state in which power transmission is interrupted.

[0003] In this one-way clutch, wedge-shaped spaces are provided at several locations on the circumference of a radially opposed space between two inner and outer rings, and rollers as wedge members are arranged in the wedge-shaped spaces. This wedge-shaped space is formed by a cam surface formed of a concave curved surface that is depressed outward in the radial direction and provided at several places on the inner peripheral surface of the outer annular member, and a cylindrical outer peripheral surface of the inner annular member.

[0004]

In recent years, it has been required to increase the maximum allowable power transmission torque while keeping the external size of the one-way clutch compact.

[0005] The maximum allowable capacity of the power transmission torque described above is:
It is determined by the pressure of the contact surface with the inner ring. The factors that determine this contact surface pressure are mainly the contact area with the inner annulus and the radial load acting on them. Here, since the radial load is specified according to the use object, it can be said that the contact area described above may be increased in order to increase the maximum allowable capacity of the power transmission torque of the one-way clutch. The area of contact with the inner ring is determined by the number of rollers, the radial and axial dimensions of the rollers, and the radius of the inner ring. These are the outer and axial dimensions required for a one-way clutch. It is restricted according to such as. Therefore, in the above-mentioned conventional one-way clutch, it is impossible to increase the maximum allowable power transmission torque capacity unless the outer diameter size is changed, and there is room for improvement here.

In addition, it is pointed out that in the case where the cam surface is provided on the inner peripheral surface of the outer ring, the engagement of the rollers tends to be weakened in a high-speed rotation region where the rotational centrifugal force increases. That is, the rolling operation of the rollers to the lock position or the free position during the rotation operation is guided while being pressed against the cam surface of the outer ring by the action of the rotary centrifugal force, but the rotary centrifugal force increases. In such a situation, the rotational centrifugal force acts to move the rollers to the side having the larger diameter, that is, the free position on the cam surface. Therefore, the roller delay angle (the angle between the lock position, the free position, and the rotation center) tends to be larger than necessary, and the lock operation tends to be delayed.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to increase the maximum allowable power transmission torque capacity of a one-way clutch without increasing the external dimensions.

[0008]

According to the present invention, there is provided a one-way clutch for switching between a locked state in which two inner and outer rings arranged concentrically are synchronously rotated and a free state in which the two rings are relatively rotated. A cam surface forming a wedge-shaped space between the inner ring and the inner surface of the outer ring is provided at several places on the outer circumferential surface of the inner ring, and the cam surface is flat or curved in the circumferential direction. It is formed on a concave curved surface.

According to a second aspect of the present invention, there is provided a one-way clutch, wherein two inner and outer rings are arranged concentrically and an inner peripheral surface of an outer annular member is provided at several locations on the outer peripheral surface of the inner annular member. A cam surface that forms a wedge-shaped space between them; a rolling element as a wedge member that is disposed one by one in each of the wedge-shaped spaces and that is displaced between a lock position and a free position to switch the state;
A cage interposed between the two annular bodies and having a plurality of pockets in which the rolling elements are accommodated one by one at a plurality of circumferential positions corresponding to the cam surface so as to be capable of rolling in the circumferential direction; and a wedge-shaped rolling element. And a resilient biasing means for resiliently biasing the narrow side of the space,
The cam surface is formed as a flat surface or a concave curved surface curved in the circumferential direction.

As described above, like the one-way clutch of the present invention,
When a cam surface consisting of a flat surface or a concave surface is provided on the inner ring body side, the contact area of the rolling element with the cam surface is reduced in consideration of the elastic deformation of the rolling element and the cam surface at the time of locking. Is larger than the contact area of the rolling element with the inner ring of the roller. As a result, the contact pressure per unit area between the inner ring body and the rolling element is reduced, so that the maximum allowable capacity of the power transmission torque is increased.

The inner peripheral surface of the outer ring body for guiding the rolling element is cylindrical, and the inner diameter of each part in the circumferential direction is constant, so that the rotational centrifugal force acting on the rolling element causes the rolling element to move. It does not act as a force to move in the circumferential direction. That is, the engagement of the rolling elements is not reduced by the rotational centrifugal force.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS.

1 to 5 relate to a first embodiment of the present invention. FIG. 1 is a longitudinal side view of a one-way clutch, and FIG.
1 is a cross-sectional view taken along the line (2)-(2) of FIG. 1, FIG. 3 is a plan development view of a pocket of the retainer, FIG.
FIG. 5 is an explanatory diagram showing a contact area between a roller and a cam surface.

In FIG. 1, A indicates the entire one-way clutch. The one-way clutch A includes an inner ring 1 as an inner ring, an outer ring 2 as an outer ring, a retainer 3, rollers 4 as rolling elements, and a coil spring 5. The operation is
According to the rotation difference between the inner ring 1 and the outer ring 2, the roller 4 rolls and switches between a state in which the inner and outer rings 1 and 2 are rotated relative to each other and a state in which the inner and outer rings 1 and 2 are synchronously rotated. Shut off or transmit power.

Hereinafter, each of the above components will be described in detail.

The inner ring 1 is provided with a flat key-like cam surface 1a at several places on the outer peripheral surface, whereby the outer peripheral surface is formed in a polygonal shape (for example, an octagon).

The outer race 2 is fitted concentrically to the outer periphery of the inner race 1 via a required facing space, and both inner and outer peripheral surfaces are formed in a cylindrical shape. The inner peripheral surface of the outer ring 2 and the inner ring 1
A wedge-shaped space is formed with the cam surface 1a.

The retainer 3 is interposed between the inner and outer rings 1 and 2 and is press-fitted to the outer peripheral surface of the inner ring 1. The retainer 3 penetrates radially inward and outward at a position corresponding to the cam surface 1 b of the inner ring 1. Pocket 3a is provided.

The rollers 4 are arranged in a wedge-shaped space formed between the cam surface 1a of the inner ring 1 and the outer ring 2 while being accommodated in the pocket 3a of the cage 3 one by one so as to be able to roll in the circumferential direction. Have been.

The coil spring 5 is provided in each pocket 3 of the holder 3.
a are stored one by one in a compressed state, and the rollers 4 are elastically urged toward the narrow side (lock side) of the wedge-shaped space formed by the cam surface 1a of the inner ring 1 and the outer ring 2 by the expansion restoring force. . The coil spring 5 is a square-wound spring in which a spring wire is wound in a rectangular shape. The coil spring 5 is externally fitted to a projection 3 b formed integrally with the inner surface of the pocket 3 a of the retainer 3, whereby the inner ring 1 is formed. The posture is substantially parallel to the cam surface 1a. One end of the coil spring 5 is engaged with a circumferential groove 3c formed at the base of the projection 3b, and is attached to the retainer 3 in a non-separable manner.

As described above, if the cam surface 1a formed of a flat surface or a concave curved surface is formed on the outer peripheral surface of the inner race 1,
Since the contact form of the roller 4 with the inner ring 1 is in contact with the cylindrical surface and the flat surface or the concave surface, the contact area of the roller 4 with the cam surface 1a of the inner ring 1 is increased as compared with the conventional example.
Therefore, the contact surface pressure between the inner ring 1 and the inner ring 4 can be reduced, so that the maximum allowable capacity of the power transmission torque of the one-way clutch A is increased. Here, calculation formulas for obtaining the maximum allowable capacity of the power transmission torque are shown for the embodiment and the conventional example.

T = b (σmax / 0.418) ² · r · (L / E) · tan θ · R T = b (σmax / 0.418) ² · (rR ² / r + R) · (L / E) tan θ , B is the number of rollers, σmax is the maximum Hertzian stress (the maximum contact pressure with the inner ring), r is the roller radius, R is the outer radius of the inner ring, L is the roller length, E is the Young's modulus, and θ is the wedge angle. It is an angle of 2. The difference in the calculation formula is due to the difference in the contact form between the roller 4 and the cam surface 1a.

Also, if the cam surface 1a is formed on the outer peripheral surface of the inner race 1, the inner peripheral surface of the outer race 2 that guides the rolling operation of the rollers 4 to the locked position or the free position is cylindrical. The rotational centrifugal force only acts to press the roller 4 against the inner peripheral surface of the outer ring 2 and does not act to move the roller in the circumferential direction. Therefore, even when the roller 4 is locked even in a high-speed rotation region where the rotational centrifugal force increases. The meshing is not weakened. Therefore, the delay angle (the angle formed by the lock position, the free position, and the rotation center) of the roller 4 can be made smaller than that in the conventional example, whereby the response of the lock operation can be improved.

It should be noted that the present invention is not limited to only the above embodiment, and various applications and modifications are conceivable.

(1) In the above embodiment, an example is given in which the cam surface 1a of the inner ring 1 is a flat surface. However, as shown in FIGS. 6 and 7, for example, a concave curved surface curved in the circumferential direction is used. Can be. The calculation formula for obtaining the maximum allowable capacity of the power transmission torque in this case is as follows.

T = b (σmax / 0.418) ² · r ₁ · r ₂ · [L / E (r ₂ −r ₁ )] tan θ · R In the above equation, r ₁ is a roller radius, and r ₂ is a concave curved surface. The radius of curvature.

In this case, when the cam surface 1a is a concave curved surface, the rollers 4 and the cam surface 1
Since the contact area with a is further increased, the maximum permissible capacity of the power transmission torque can be further increased as is apparent from the above formula.

(2) In the above embodiment, the rolling elements may be balls in addition to the rollers 4. In this case, it is preferable to provide a ball rolling guide groove on at least one of the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2 so that the ball is guided to roll in a straight line in the circumferential direction.

(3) The one-way clutch A can be built in pulleys of various auxiliary machines mounted on engines such as automobiles. Specifically, a case where an alternator is used as an auxiliary machine will be described with reference to FIG. In this case, between the pulley 20 and the rotor 21 of the alternator,
The one-way clutch A according to the above-described embodiment is interposed, and rolling bearings 22, such as a deep groove ball bearing are disposed on both axial sides of the one-way clutch A. In this case, the one-way clutch A switches between the free state and the locked state according to the rotation difference between the pulley 20 and the rotor 21, and the pulley 2
The rotation power is transmitted from 0 to the rotor 21 or cut off. In the alternator, pulley 2
0 is rotationally driven by the crankshaft of the engine via the belt 23. Therefore, conventionally, for example, when the rotation speed of the crankshaft decreases, the power generation efficiency of the alternator decreases. If
When the rotation speed of the pulley 20 decreases, the one-way clutch A can function so that the rotation speed of the rotor 21 is maintained at a high range by its own inertial force, so that it is possible to contribute to improvement in power generation efficiency. . Also, due to the rotation fluctuation from the crankshaft and the inertia force of the alternator rotor shaft,
It is possible to prevent the belt from being stressed, thereby shortening the life of the belt and generating noise due to slippage.

[0030]

In the one-way clutch according to the first and second aspects of the present invention, the contact area of the rolling element with the cam surface at the time of locking can be increased as compared with the conventional example.
The contact pressure per unit area between the cam surface and the rolling element can be reduced, and the maximum allowable power transmission torque can be increased. In short, in the present invention, the contact area between the inner ring and the rolling element is increased by devising the contact form between the inner ring and the rolling element regardless of the external dimensions of the one-way clutch. Therefore, it is possible to increase the maximum allowable capacity of the power transmission torque while keeping the external dimensions of the one-way clutch compact.

Further, if the inner peripheral surface of the outer ring body for guiding the rolling elements is made cylindrical by forming the cam surface on the inner ring body, the inner diameter of each part in the circumferential direction is constant. The rotational centrifugal force acting on the rolling element does not act as a force to move the rolling element in the circumferential direction. In other words, the meshing property of the rolling elements is not reduced by the rotational centrifugal force, so that the delay angle of the rolling elements (the angle between the lock position, the free position, and the rotation center) can be made smaller than in the conventional example. Thereby, the response of the locking operation can be improved.

As described above, according to the present invention, it is possible to provide a one-way clutch exhibiting a stable and highly reliable clutch function.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a one-way clutch according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line (2)-(2) of FIG.

FIG. 3 is an expanded plan view of the pocket of the cage according to the embodiment.

FIG. 4 is a perspective view showing the inner race of the embodiment.

FIG. 5 is an explanatory diagram showing a contact area between a roller and a cam surface in the embodiment.

FIG. 6 is a one-way clutch according to another embodiment of the present invention, the view corresponding to FIG. 2;

FIG. 7 is a view corresponding to FIG. 4 in the embodiment shown in FIG. 6;

FIG. 8 is a sectional view of an upper half showing a pulley unit including a one-way clutch of the present invention.

[Explanation of symbols]

 A One-way clutch 1 Inner ring 1a Inner ring cam surface 2 Outer ring 3 Cage 3a Cage pocket 4 Roller as rolling element 5 Coil spring

Claims (2)

[Claims] 1. A one-way clutch for switching between a locked state in which two inner and outer rings arranged concentrically are rotated synchronously and a free state in which the two rings are rotated relative to each other, wherein the inner ring has several circumferential positions on the outer peripheral surface thereof. A cam surface forming a wedge-shaped space between the outer ring body and the inner peripheral surface thereof, and the cam surface is formed as a flat surface or a concave curved surface curved in the circumferential direction. One-way clutch to do. 2. A wedge-shaped space is formed between two inner and outer rings arranged concentrically and several inner circumferential surfaces of an outer circumferential surface of an inner annular body. A cam surface; a rolling element as a wedge member that is disposed one by one in each of the wedge-shaped spaces and that is displaced between a lock position and a free position to switch a state; and is interposed between the two ring bodies. A retainer having pockets in which the rolling elements are accommodated one by one in a number of circumferential positions corresponding to the cam surface so as to be able to roll in the circumferential direction, and a bullet that urges the rolling elements toward a narrow side of the wedge-shaped space. A one-way clutch, comprising: urging means; wherein the cam surface is formed as a flat surface or a concavely curved surface curved in a circumferential direction.