JP4893997B2 - One-way clutch - Google Patents

Description

The present invention relates to a one-way clutch, and more particularly to a one-way clutch in which a wedge member is urged in one direction by a coil spring in a pocket of a cage disposed between an outer ring and an inner ring.

The one-way clutch is built in, for example, a pulley unit provided in an engine accessory driven from a crankshaft of an engine such as an automobile via a belt. Examples of the engine auxiliary machine include a compressor for an air conditioner of a car, a water pump, an alternator, a cooling fan, and a crank pulley.

Some pulley units used in engine accessories such as alternators have built-in one-way clutches for the purpose of absorbing rotational fluctuations. Many of the one-way clutches use an engaging roller as a wedge member. However, as a biasing means for biasing the engaging roller in one direction, a spring receiving projection in a pocket of the cage is used. A coil spring that is fitted and positioned is used (for example, see Patent Document 1).
Japanese Unexamined Patent Publication No. 2004-060851 (FIG. 1, paragraph 0016)

By the way, since the maximum rotation speed of the alternator reaches 20000 r / min, the coil spring of the one-way clutch is deformed so as to be swung up with respect to the engaging roller when a centrifugal force is applied to the inner peripheral surface of the outer ring. Contact can cause wear. For this reason, the coil spring cannot urge the wedge member with an appropriate force, or the wear powder bites in and the function as the one-way clutch cannot be maintained, and the life of the one-way clutch is shortened. There was a problem.

In view of the above-described points, an object of the present invention is to provide a one-way clutch in which a wedge member side tip of a coil spring is prevented from being deformed by a centrifugal force and coming into contact with an inner peripheral surface of an outer ring.

Means for Solving the Problems and Effects of the Invention

In order to achieve the above object, the one-way clutch of the present application is a one-way clutch in which a wedge member is urged in one direction by a coil spring in a pocket of a cage disposed between an outer ring and an inner ring. The coil spring is a coil spring that tapers toward a contact side with the wedge member, and the inner side in the radial direction is substantially parallel to a plane perpendicular to the radial direction . According to this one-way clutch, since the coil spring is tapered toward the contact side with the wedge member, the spring constant is increased and the mass is reduced, and the space in the pocket of the cage (coil spring Since the clearance between the tip and the inner peripheral surface of the outer ring is increased, the coil spring is prevented from being deformed by the centrifugal force and coming into contact with the inner peripheral surface of the outer ring to cause wear. For this reason, the lifetime of a one-way clutch can be extended, maintaining the function of a one-way clutch.

In this one-way clutch, the coil spring may have a symmetrical shape in the radial direction . According to this one-way clutch, since the coil spring has a symmetrical shape in the radial direction, it is not necessary to consciously assemble the coil spring to the spring receiving projection in the cage pocket, and assembly is easy. There is an effect of becoming.

In the coil spring of the one-way clutch, the inner side in the radial direction is substantially parallel to a plane perpendicular to the radial direction . According to this one-way clutch, since the inner side of the radial direction of the coil spring is substantially parallel to the surface perpendicular to the radial direction, the coil spring is more difficult to deform outwardly in the radial direction, In addition, since the clearance between the coil spring and the inner peripheral surface of the outer ring is increased, the contact between the coil spring and the inner peripheral surface of the outer ring is more reliably prevented.

In the one-way clutch of the present invention, it is desirable that the pitches of the coil springs are equally spaced. According to such a one-way clutch, since the coil spring is tapered toward the contact side with the wedge member and the pitch is equally spaced, the spring constant on the tip side of the coil spring is increased and the tip of the coil spring is more The effect that it becomes difficult to bend is acquired.

Furthermore, in the one-way clutch of the present invention, it is preferable that the spring receiving protrusion in the pocket of the cage is a frustum-shaped protrusion. According to such a one-way clutch, since the spring receiving protrusion in the cage pocket is a frustum-shaped protrusion, the tapered coil spring is moved from the frustum-shaped bottom opening to the spring receiving protrusion in the cage pocket. The effect that it can be assembled easily is obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

The object of preventing the tip of the coil spring on the wedge member side from being deformed by the centrifugal force and coming into contact with the inner peripheral surface of the outer ring is achieved by tapering the coil toward the wedge member.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an upper half front sectional view showing a pulley unit 100 including a one-way clutch 10 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the pulley unit 100 shown in FIG.

The pulley unit 100 is configured, for example, by providing a one-way clutch 10 between a hollow shaft 2 fitted to a rotor shaft 2b of an alternator (not shown) and a pulley 1 arranged concentrically therewith. Yes. The one-way clutch 10 is of a so-called roller type that uses the engaging roller 5 as a wedge member. On both sides of the one-way clutch 10, ball bearings 21 and roller bearings 22 are disposed as support bearings. The pulley 1, the outer ring of the one-way clutch 10 and the outer ring of the ball bearing 21 and the roller bearing 22 are integrated, and the hollow shaft 2, the inner ring of the one-way clutch 10, the ball bearing 21 and the inner ring of the roller bearing 22 are integrated. And are integrated.

The one-way clutch 10 includes an inner peripheral engagement surface 1a of a pulley 1 as an outer ring, a cam surface 2a of a hollow shaft 2 as an inner ring, an engagement roller 5 as a wedge member, and an engagement roller 5 as a pulley 1. It is comprised from the retainer 3 hold | maintained between the hollow shafts 2, and the taper coil spring 4 as a biasing member which biases the engagement roller 5 to the biting direction (narrow side of a wedge-shaped space). The one-way clutch 10 switches between a locked state and a free state according to the rotational difference between the pulley 1 and the hollow shaft 2, and transmits or interrupts rotational power from the pulley 1 to the hollow shaft 2.

Seal members 25 and 26 are respectively arranged on the outer sides in the axial direction of the ball bearing 21 and the roller bearing 22, and on the free end side (left side in FIG. 1) of the pulley unit 100, In order to prevent intrusion of muddy water or the like, another seal member 27 is arranged. Grease is sealed in the sealed space sealed by the seal members 25, 26, and 27.

The pulley 1 is a steel cylinder having an inner peripheral engagement surface 1a that is an inner peripheral surface that has been hardened by carburizing, carbonitriding, or induction hardening. On the outer periphery of the pulley 1, for example, a belt spanning portion is provided on which the other end of a belt spanning one end of an engine pulley (not shown) of the engine is spanned.

The hollow shaft 2 is made of carbon steel such as S45C or S55C, or case-hardened steel such as SCR, SCM or SNCM, and is formed into a cylindrical shape. It is formed on the cam surface 2a which is the outer peripheral surface of the cylindrical body. That is, in the middle of the outer peripheral surface of the hollow shaft 2, four pairs of cam surfaces 2 a and 2 a facing each other with the rotation center axis O interposed therebetween are provided in the circumferential direction. The cam surface 2a may be a flat surface or an eccentric round cam surface. By providing the cam surface 2 a on the outer peripheral surface of the hollow shaft 2, the hollow shaft 2 is provided with a function as an inner ring of the one-way clutch 10, and the hollow shaft 2 and the inner ring of the one-way clutch 10 are integrated. Has been fulfilled. The hollow shaft 2 can be processed by cold forging instead of machining, and thereby the processing cost of the pulley unit 100 including the one-way clutch 10 can be reduced.

The cage 3 is formed of an annular body made of synthetic resin, and has an outer peripheral shape substantially along the inner peripheral engagement surface 1 a of the pulley 1 and an inner peripheral shape along the cam surface 2 a of the hollow shaft 2. And is press-fitted into the pulley 1. A slight gap is provided between the cage 3 and the inner peripheral engagement surface 1 a of the pulley 1. The cage 3 is provided with a tapered truncated pyramid-shaped spring receiving projection 3 a (see FIG. 3) for positioning the coil spring 4 on the pillar portion of the cage 3. Since the spring receiving projection 3a is a tapered truncated pyramid shaped projection, the tapered coil spring 4 can be easily assembled into the pocket 6 of the cage 3 from the bottom side opening (base end) of the truncated pyramid shape. The central end of the coil spring 4 is kept substantially parallel to the cam surface 2a.

The coil spring 4 has a truncated pyramid shape that is symmetrical in the radial direction, and the winding pitch is equally spaced so that the effective diameter of the coil spring 4 decreases as it goes the spring steel wire first. It is formed by winding. However, the coil spring 4 may be a truncated cone shape or an elliptical truncated cone shape. The coil spring 4 is positioned with respect to the movement in the radial direction by fitting the base end of the coil spring 4 into the spring receiving projection 3a of the retainer 3 and storing the coil spring 4 in the wedge-shaped space. With this positioning, the central axis of the coil spring 4 is kept substantially orthogonal to the central axis of the engaging roller 5 and parallel to the cam surface 2a, as shown in FIG. By making the coil spring 4 symmetrical in the radial direction, when the coil spring 4 is assembled to the spring receiving projection 3 a in the pocket 6 of the cage 3, it is not necessary to be aware of the vertical direction, and the assembly is easy. In addition, since the coil spring 4 is tapered toward the contact side with the engaging roller 5 and the pitch is equal, the spring constant of the tip of the coil spring 4 is increased, and the tip of the coil spring 4 is less likely to bend. .

The engaging roller 5 is made of a steel cylindrical body, and is urged in a circumferential direction by a coil spring 4 in a pocket 6 which is a space formed in the cage 3 so as to be rotatable. In other words, the engaging roller 5 rotates in a wedge-shaped space formed by the cam surface 2 a provided on the outer peripheral surface of the hollow shaft 2, the cam surface 2 a and the inner peripheral engaging surface 1 a of the pulley 1. Arranged freely.

When assembling the pulley unit 100, the ball 1 and the cage of the ball bearing 21, the cage 3 of the one-way clutch 10, the coil spring 4 and the engaging roller 5, the rollers and the cage of the roller bearing 22 are arranged in this order. What is necessary is just to insert between the axis | shafts 2. A space for work is secured outside in the radial direction during each insertion work, and the assembly work can be easily performed.

Next, operation | movement of the pulley unit 100 provided with the one way clutch 10 which concerns on Example 1 comprised in this way is demonstrated.

First, when the pulley 1 rotates relative to the hollow shaft 2 in the direction of the arrow B in FIG. 1, the engaging roller 5 moves in a direction in which the coil spring 4 extends, and the inner peripheral engaging surface of the pulley 1. It is bitten by the narrow side of the wedge-shaped space between 1a and the cam surface 2a of the hollow shaft 2. As a result, power is transmitted between the pulley 1 and the hollow shaft 2, and the pulley 1 and the hollow shaft 2 rotate together. That is, the one-way clutch 10 is locked.

At the time of high-speed rotation of the engine, the engaging roller 5 is positioned by the cam surface 2a and is in contact with the hollow shaft 2, and the coil spring 4 receives a force in a direction of contraction due to a centrifugal force due to a predetermined rotational speed of the pulley 1, The elastic force that urges the engaging roller 5 in the biting direction is reduced, and a contact state between the engaging roller 5 and the hollow shaft 2 is ensured. Since the moving direction of the engaging roller 5 when the centrifugal force is applied and the central axis direction of the coil spring 4 substantially coincide with each other, the coil spring 4 is deformed by the centrifugal force when the engaging roller 5 moves, and the pulley. No contact is caused with the inner peripheral engagement surface 1a.

On the other hand, when the pulley 1 rotates relative to the hollow shaft 2 in the direction of the arrow C in FIG. 1, for example, the hollow shaft 2 rotates at a high speed, and when the pulley 1 stops rotating, the engaging rollers 5 Then, the coil spring 4 is moved in the direction of compressing to the wide side of the wedge-shaped space, and the loose engagement state is established between the inner peripheral engagement surface 1 a of the pulley 1 and the cam surface 2 a of the hollow shaft 2. Thereby, power transmission is interrupted between the pulley 1 and the hollow shaft 2, and the one-way clutch 10 enters a free state. At this time, since the ball bearing 21 and the bearing 22 support the radial load on both sides of the one-way clutch 10, the one-way clutch 10 can maintain good meshing performance and durability.

According to the first embodiment, since the coil spring 4 is formed to be tapered toward the contact side with the engaging roller 5, the spring constant of the coil spring 4 is increased, the mass is reduced, and the pocket of the cage 3 is increased. 6 (the clearance between the tip of the coil spring 4 and the inner peripheral engagement surface 1a of the pulley 1) increases, so that the coil spring 4 is deformed by centrifugal force and comes into contact with the inner peripheral engagement surface 1a of the pulley 1. This can prevent the wear from occurring. For this reason, the lifetime of the one-way clutch 10 can be extended.

Further, according to the first embodiment, the coil spring 4 has a symmetrical shape in the radial direction, so that it is necessary to assemble the coil spring 4 in consideration of the vertical direction when the coil spring 4 is assembled to the spring receiving protrusion 3a in the pocket 6 of the cage 3. The one-way clutch 10 can be easily assembled.

Further, according to the first embodiment, the coil spring 4 is tapered toward the contact side with the engaging roller 5 and the pitch is equal, so that the spring constant on the tip side of the coil spring 4 is increased. Therefore, deformation due to the centrifugal force of the coil spring 4 can be suppressed.

Furthermore, according to the first embodiment, since the spring receiving projection 3a in the pocket 6 of the cage 3 is a truncated pyramid shaped projection, the tapered coil spring 4 is moved from the bottom side opening of the truncated pyramid shape to the pocket of the cage 3. 6 can be easily assembled to the spring receiving projection 3a.

FIG. 4 is a cross-sectional view of a main part of the one-way clutch 10 according to the second embodiment of the present invention. In the one-way clutch 10 according to the first embodiment shown in FIGS. 1 to 3, the coil spring 4 has a symmetrical shape in the radial direction, whereas in the one-way clutch 10 according to the second embodiment, the coil spring 4 has a symmetrical shape. 4A is different in that the radially inner side is substantially parallel to the cam surface 2a. Further, because the coil spring 4A is asymmetric in the radial direction, the spring receiving projection 3b of the cage 3 is also formed so that the inner side in the radial direction is substantially parallel to a plane perpendicular to the radial direction.

In addition, since it is comprised similarly to the one-way clutch 10 which concerns on Example 1 about the other part which is not mentioned especially, illustration and description are abbreviate | omitted.

According to the one-way clutch 10 according to the second embodiment configured as described above, the engagement roller 5 side tip of the coil spring 4A is more cam surface of the hollow shaft 2 than the one-way clutch 10 according to the first embodiment. Since it is close to 2a, the coil spring 4A is more difficult to deform outward in the radial direction, and the clearance between the coil spring 4A and the inner peripheral engagement surface 1a of the pulley 1 is increased, so that the centrifugal force of the coil spring 4A is increased. Due to the deformation caused by the above, the coil spring 4A is more reliably prevented from coming into contact with the inner peripheral engagement surface 1a of the pulley 1.

In each of the above embodiments, the inner peripheral surface of the pulley 1 is the inner peripheral engagement surface 1a and the outer peripheral surface of the hollow shaft 2 is the cam surface 2a. However, the inner peripheral surface of the outer ring is the cam surface, and the outer periphery of the inner ring is The surface may be an outer peripheral engagement surface.

In each embodiment, the wedge member of the one-way clutch 10 is the engaging roller 5. However, it goes without saying that the present invention can be similarly applied to a one-way clutch in which the wedge member is a ball or the like.

Moreover, in each Example, although the ball bearing 21 and the bearing 22 were provided in the position adjacent to the both ends of the axial direction of the one-way clutch 10, you may abbreviate | omit one or both of these bearings. Good.

The upper half front sectional view showing a pulley unit provided with the one way clutch concerning Example 1 of the present invention. AA sectional drawing of the pulley unit of FIG. FIG. 3 is an enlarged cross-sectional view of a main part of the one-way clutch according to the first embodiment. The principal part expanded sectional view of the one-way clutch which concerns on Example 2 of this invention.

Explanation of symbols

1 Pulley (outer ring)
1a Inner peripheral engagement surface 2 Hollow shaft (inner ring)
2a Cam surface 3 Cage 3a, 3b Spring receiving projection 4, 4A Coil spring 5 Engaging roller (wedge member)
6 Pocket 10 One-way clutch 100 Pulley unit

Claims (1)

In the one-way clutch formed by biasing a wedge member in one direction by a coil spring in a pocket of a cage disposed between the outer ring and the inner ring,
The one-way clutch, wherein the coil spring is a coil spring that tapers toward a contact side with the wedge member, and an inner side in a radial direction is substantially parallel to a plane perpendicular to the radial direction. .

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