JP4940994B2 - One-way clutch - Google Patents

Description

  The present invention relates to a one-way clutch that switches between a locked state in which an inner ring body and an outer ring body that are concentrically arranged inside and outside in a radial direction are synchronously rotated and a free state in which the inner ring body is relatively rotated.

This type of one-way clutch may be assembled to a pulley unit used in, for example, engine accessories (alternator, compressor for air conditioner, water pump, cooling fan, etc.).
In this case, it is arranged between a pulley around which a transmission belt for transmitting the torque of the crankshaft of the engine is stretched and a shaft body that is connected to a rotor (rotor shaft) of an alternator as auxiliary equipment so as to be integrally rotatable. Then, torque is transmitted from the pulley to the shaft body or cut off.
The one-way clutch includes a plurality of one-way clutches between opposing circumferential surfaces of an inner ring body (which may be configured by a shaft body corresponding to the rotor itself) and an outer ring body (which may be configured by a pulley itself). The wedge-shaped spaces are formed at predetermined intervals in the circumferential direction. In the plurality of wedge spaces, the same number of rollers and coil springs for individually urging each roller toward the narrow side of the wedge-shaped space are disposed in a state of being accommodated in the pockets of the cage. A structure having a different structure is known (for example, see Patent Document 1).
In this type of one-way clutch, if there is no gap between both end surfaces of the roller and the inner surfaces of both side walls of the cage pocket, the tilting of the roller is restrained if the contact state is maintained. In this state, when the roller is moved to the narrow side of the wedge-shaped space (the locked state) by the elastic force (biasing force) of the coil spring, the roller hits the wedge surface on the narrow side of the wedge-shaped space. There is a risk of biting in a state (relatively inclined state).
For this reason, in consideration of the wedge surface of the wedge-shaped space and variations in the processing accuracy of the roller, the roller tilts slightly between the opposite surfaces of the roller end surfaces and the inner surfaces of both side walls of the cage pocket. A clearance that allows a tilt of a certain angle) is set. As a result, even if there are variations in the wedge surface of the wedge-shaped space and the processing accuracy of the rollers, the roller is well engaged with the wedge surface on the narrow side of the wedge-shaped space to transmit torque.
JP 2003-214462 A

By the way, in the conventional one-way clutch described above, when the inner ring body and the outer ring body are in a free state in which the inner ring body and the outer ring body rotate relative to each other, the roller slides on the raceway surface of the outer ring body or the inner ring body in the wedge-shaped space. Exciting vibration) may occur, which may cause abnormal noise.
For example, when a one-way clutch is used in a pulley unit of an alternator, which is one of the engine accessories, when the rotation of the pulley (outer ring body) stops when the engine stops, the roller of the one-way clutch It moves from the locked position to the wide side of the wedge-shaped space and switches to the free state. Thereby, the transmission of torque from the pulley is interrupted, but the shaft body (inner ring body) of the rotor of the alternator continues to rotate until the inertial force disappears after the interruption because the rotor has a large rotational inertia.
And in a quiet state where the engine is stopped, the roller easily causes stick-slip just before the rotation of the shaft body (inner ring body) of the alternator rotor. there were.

  In view of the above problems, an object of the present invention is to provide a one-way clutch capable of preventing the occurrence of abnormal noise by suppressing stick slip of a roller.

In order to achieve the object, the one-way clutch according to claim 1 of the present invention is a free state in which the inner ring body and the outer ring body, which are concentrically disposed inside and outside in the radial direction, are synchronously rotated with the locked state. A one-way clutch that switches between
A plurality of wedge-shaped spaces are formed at predetermined intervals in the circumferential direction between the opposed peripheral surfaces of the inner ring body and the outer ring body,
In the plurality of wedge spaces, the same number of rollers and coil springs individually energizing the rollers in the locking direction for engaging each of the rollers in the wedge-shaped spaces are arranged in a state of being accommodated in the pockets of the cage. And
As a contact portion that holds the roller in a tiltable manner on one surface of the opposing surfaces of the both axial end surfaces of the roller and the inner surfaces of both side walls in the axial direction of the pocket while being in point contact with the other surface. projections provided, et al are of
When the roller is assembled in the pocket, the roller is elastically held by elastically deflecting both side walls of the pocket by the convex portion .

According to the above construction, the end surfaces of the roller, the surface facing the side walls the inner surface of the pocket, the roller can be tilted in a state in which the convex portion is touched point contact with the other surface of the contact portion provided on one surface Can be held in.
Even if there is a variation in the wedge surface of the wedge-shaped space or the processing accuracy of the roller, it is possible to transmit the torque by properly engaging the wedge surface on the narrow side of the wedge-shaped space by the tilting of the roller.
In particular, the roller can be elastically held by elastically deflecting both side walls of the pocket by the convex portion as the contact portion. Thereby, stick-slip can be suppressed and generation of abnormal noise can be prevented.

The one-way clutch according to claim 2 is the one-way clutch according to claim 1,
The convex portion of the contact portion, characterized in that it is protruded from the side walls the inner surface of the pocket of the cage.
According to the said structure, when forming a holder | retainer by the press work of a metal plate material, it becomes possible to form easily the convex part as a contact part by press work in the inner surface of the both sides of each pocket of a holder | retainer.
Further, when the cage is formed by injection molding of synthetic resin, it is possible to form a convex portion as a contact portion simultaneously with the injection molding.
As described above, it is possible to reduce costs by forming convex portions as contact portions on the inner surfaces of both side walls of each pocket of the cage.

The one-way clutch according to claim 3 is the one-way clutch according to claim 1,
The convex portion of the contact portion, characterized in that it is projected from the substantially central portion of the end surfaces of the roller.
According to the said structure, the convex part as a contact part is formed in the approximate center part of the both end surfaces of a roller, and a roller can always be hold | maintained so that tilting is possible in the stable state. As a result, even if there is a variation in the wedge surface of the wedge-shaped space or the processing accuracy of the roller, the roller can be satisfactorily engaged with the wedge surface on the narrow side of the wedge-shaped space by the stable tilting of the roller, and the stick of the roller Greatly effective in suppressing slip.

  Next, the best mode for carrying out the present invention will be described with reference to examples.

Example 1
A first embodiment of the present invention will be described with reference to FIGS.
1 is a side sectional view showing a pulley unit including a one-way clutch according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view based on the line II-II in FIG. FIG. 3 is an enlarged plan view showing a state where rollers and coil springs are housed in the pockets of the cage. FIG. 4 is an enlarged side view showing a state in which a roller and a coil spring are stored in a pocket of the cage.
As shown in FIG. 1, the pulley unit including the one-way clutch according to the first embodiment exemplifies a case where the pulley unit is used for an alternator that is one of auxiliary components of an in-vehicle engine. 11, a pulley 21, a one-way clutch 30, a ball bearing 50, a roller bearing 55, and seal members 58 and 59.

As shown in FIGS. 1 and 2, the shaft body 11 is formed in a cylindrical shaft shape that is attached around the tip end shaft of the rotor shaft (not shown) of the rotor of the alternator. A female screw 12 that is fastened to a male screw portion formed on the tip end side of the rotor shaft is formed at a substantially central portion in the axial direction of the inner hole of the shaft body 11, and an opening on one end side of the inner hole of the shaft body 11 is formed. A hexagonal hole-shaped fastening recess 13 into which a fastening tool such as a hexagonal bar can be fitted is formed.
In the first embodiment, the shaft body 11 constitutes the inner ring bodies of the one-way clutch 30, the ball bearing 50, and the roller bearing 55.

  As shown in FIGS. 1 and 2, the pulley 21 is concentrically disposed on the outer periphery of the shaft body 11 and constitutes the outer ring bodies of the one-way clutch 30, the ball bearing 50, and the roller bearing 55, and the outer periphery thereof. On the surface, a belt groove 22 having a corrugated cross section is formed on which the transmission belt 8 is stretched. The transmission belt 8 is stretched around the pulley of the crankshaft of the engine and transmits the torque of the crankshaft to the pulley 21.

As shown in FIGS. 1 and 2, the one-way clutch 30 includes a shaft body 11 as an inner ring body, a pulley 21 as an outer ring body, and an axial center of an annular space between the shaft body 11 and the pulley 21. In the region, a plurality of rollers 40 arranged at predetermined intervals in the circumferential direction, a coil spring 45 for individually urging these rollers 40 in the lock direction, and a plurality of rollers 40 and the coil spring 45 are held. And a cage 31.
That is, a plurality (eight in the figure) of wedge-shaped spaces are formed at predetermined intervals in the circumferential direction between the opposed peripheral surfaces of the shaft body 11 and the pulley 21. The same number of rollers 40 and coil springs 45 for individually urging each of the rollers 40 in the locking direction (the narrow side of the wedge space) are arranged in a state of being accommodated in the respective pockets 34 of the cage 31. (See FIG. 3).
In the first embodiment, on the outer peripheral surface of the shaft body 11, in order to form a plurality of wedge spaces, the same number of flat cam surfaces 15 (or curved surfaces) as the plurality of wedge spaces are formed in the circumferential direction. As a result, the outer peripheral surface of the shaft body 11 forms a regular polygon (a regular octagon in FIG. 2), while the inner peripheral surface of the pulley 21 is circular.
The coil spring 45 is formed by winding a spring wire into an elliptical shape, a rectangular shape or the like.

As shown in FIGS. 3 and 4, the retainer 31 has a polygonal inner shape that is fitted and fixed (for example, press-fitted and fixed) to the outer peripheral surface of the shaft body 11 with a predetermined gap between both end surfaces in the axial direction of the roller 40. A pair of end plates 32 each having a hole penetrating at the center thereof and a column portion 35 for defining a plurality of pockets 34 between the pair of end plates 32 are integrally formed.
On one side surface (the surface facing the narrow side of the wedge space) of each column portion 35 of the retainer 31, a protrusion 36 into which the proximal end winding portion of the coil spring 45 is inserted is provided.
The coil spring 45 has a proximal winding portion fitted into the protrusion 36 of the column portion 35, and the distal winding portion is supported on the outer peripheral surface of the roller 40 with the base portion of the protrusion 36 supported as a spring seat. The roller 40 is elastically biased toward the narrow side (the side in the locked state) of the wedge-shaped space formed by the cam surface 15 of the shaft body 11 and the inner peripheral surface of the pulley 21.

As shown in FIGS. 3 and 4, one of the opposing surfaces of the axial end surfaces 41 of the roller 40 and the inner surfaces 32a of the side walls in the axial direction of the pocket 34 (the inner surface of the end plate 32) is on the other side. A convex portion 48 is provided as a contact portion that holds the roller 40 so as to be tiltable in a state of being in local contact with the surface.
In the first embodiment, the interval dimension between the side wall inner surfaces 32a of the pocket 34 is set to be appropriately larger than the length dimension of the roller 40, and the side wall inner surface 32a has a convex portion such as a circular arc or hemispherical section. 48 protrudes.

In addition, the distance between the opposite ends of the convex portions 48 of the inner surfaces 32a of both side walls of the pocket 34 is set to be slightly smaller than the length of the roller 40, whereby the length of the roller 40 varies. Even so, when the roller 40 is assembled in the pocket 34, both the convex portions 48 are surely in contact with both end faces of the roller 40 in a point contact state.
Further, when the roller 40 is assembled to the pocket 34, the both side walls (the pair of end plates 32) of the pocket 34 are elastically bent slightly by the both convex portions 48, thereby elastically holding the roller 40. It is like that.
Further, by reducing the thickness and width of both side walls (a pair of end plates 32) of the pocket 34 and thereby reducing the spring constant, the distance between the opposing tips of both convex portions 48, the roller 40 It is desirable to set so that the frictional force between both convex portions 48 and both end faces 41 of the roller 40 is not easily changed due to variations in the length dimension of the roller 40.
Note that the elastic force (biasing force) of the roller 40 by the coil spring 45 resists the mutual contact frictional force between the convex portions 48 of the inner surface 32 a on both side walls of the pocket 34 and the both end surfaces 41 of the roller 40. It is set so that it can be pressed to a state where it is engaged with the wedge surface on the narrow side of the wedge-shaped space (the side that is in the locked state).

The cage 31 is integrally formed by pressing a metal plate material or injection molding a synthetic resin material.
When the cage 31 is formed by pressing a metal plate material, convex portions 48 as contact portions are formed by pressing on both side wall inner surfaces 32 a of the pockets 34 of the cage 31.
Further, when the cage 31 is formed by injection molding of a synthetic resin material, a convex portion 48 as a contact portion is formed simultaneously with the injection molding.

As shown in FIG. 1, in an annular space between the shaft body 11 and the pulley 21, a plurality of ball bearings 51 serving as rolling bearings are formed on one of both sides of the cage 31 of the one-way clutch 30. The ball 52 is disposed so as to be able to roll while being held by the cage 53. Further, a plurality of rollers 57 constituting a roller bearing 56 as a rolling bearing are arranged on the other of both sides of the cage 31 so as to be able to roll while being held by the cage 58.
Further, seal rings 60 and 61 for sealing the annular space are mounted in the vicinity of both openings of the annular space.

The pulley unit including the one-way clutch according to the first embodiment is configured as described above.
Accordingly, when the rotational speed of the pulley 21 is higher than the rotational speed of the shaft body 11, the one-way clutch 30 is locked, so that the shaft body 11 rotates integrally with the pulley 21.
Further, when the roller 40 is locked to the narrow side of the wedge-shaped space, even if there is a wedge surface of the wedge-shaped space or a variation in processing accuracy of the roller 40, the inner surfaces 32a of the side walls of the pocket 34 are not affected. By the tilting of the roller 40 held between the convex portions 48, the roller 40 can be satisfactorily engaged with the wedge surface on the narrow side of the wedge-shaped space, and torque can be transmitted.

Further, when the rotation speed of the pulley 21 becomes slower than the rotation speed of the shaft body 11, the roller 40 of the one-way clutch 30 moves out of the lock position and moves to the wider side of the wedge-shaped space and switches to the free state. Thereby, transmission of torque from the pulley 21 is interrupted, but the shaft body 11 corresponding to the alternator rotor continues to rotate after the interruption because the alternator rotor has a large rotational inertia.
In particular, when the engine is stopped, the rotation of the pulley (outer ring body) is stopped with the stop, and the shaft body 11 continues to rotate until the rotational inertia force of the rotor of the alternator disappears.
Then, in a quiet state where the engine is stopped, the roller 40 causes stick-slip just before the rotation of the shaft body 11 stops, for example, after the rotation of the shaft body 11 reaches 800 rpm / min or less and stops. Cheap.
At this time, stick slip (self-excited vibration) of the roller 40 can be suppressed by the holding force due to mutual contact friction between the convex portions 48 of the side wall inner surfaces 32a of the pocket 34 and the end surface of the roller 40. It is possible to prevent the generation of abnormal noise.

Further, in the first embodiment, when the cage 31 is formed by pressing a metal plate material, the convex portions 48 can be easily formed on the inner surfaces of both side walls of each pocket 34 of the cage 31 by pressing. It becomes.
Further, when the retainer 31 is formed by injection molding of synthetic resin, the convex portion 48 can be formed simultaneously with the injection molding.
As described above, the cost can be reduced by forming the convex portions 48 on the inner surfaces of both side walls of each pocket 34 of the cage 31.

(Example 2)
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is an enlarged plan view showing a state in which a roller and a coil spring are housed in a pocket of a cage of a one-way clutch used in a pulley unit according to Embodiment 2 of the present invention. FIG. 6 is an enlarged side view showing a state in which a roller and a coil spring are stored in a pocket of the cage.
As shown in FIGS. 5 and 6, in the second embodiment, the roller 40 is projected between the inner surfaces 32a of the side walls in the axial direction of the pocket 34 (the inner surfaces of the pair of end plates 32) so as to be tiltable. The part 148 protrudes from the substantially center part of both end surfaces 41 in the axial direction of the roller 40 in a circular arc shape, a hemispherical shape, or the like.
In addition, the distance between the inner surfaces 32a of both side walls of the pocket 34 is set slightly smaller than the distance between the opposite ends of the two convex portions 148 of the roller 40, whereby the distance between the inner surfaces 32a of both sides of the pocket 34 is set. Even if the distance between the tips of the convex portions 148 of the roller 40 varies, when the roller 40 is assembled to the pocket 34, the both convex portions 148 of the roller 40 are formed on the inner surfaces 32a on both side walls of the pocket 34. The tip is surely contacted in a point contact state.
When the roller 40 is assembled in the pocket 34, both the side walls (the pair of end plates 32) of the pocket 34 are elastically bent slightly by the both convex portions 148, thereby elastically moving the roller 40 in the pocket 34. It is supposed to hold on.
Since other configurations of the second embodiment are configured in the same manner as the first embodiment, the same components are denoted by the same reference numerals, and the description thereof is omitted.

  In the pulley unit including the one-way clutch according to the second embodiment configured as described above, the convex portion 148 as the contact portion is formed at the substantially central portion of the both end surfaces 41 of the roller 40, so that the roller 40 is It can be kept tiltable in a stable state at all times. As a result, even if there are variations in the wedge surface of the wedge-shaped space and the processing accuracy of the roller 40, the roller 40 can be tilted stably with the substantially center portions of the both end surfaces 41 of the roller 40 being supported. As a result, the roller 40 can be satisfactorily engaged with the wedge surface on the narrow side of the wedge-shaped space. Further, the effect of suppressing stick-slip of the roller 40 is great.

The present invention is not limited to the first and second embodiments.
For example, in the first and second embodiments, the cam surface 15 is formed on the outer peripheral surface of the shaft body 11 and the wedge-shaped space is formed by the inner peripheral surface of the pulley 21 and the cam surface 15. Alternatively, a cam surface may be formed, and a wedge-shaped space may be formed by the outer peripheral surface of the shaft body 11 and the cam surface.
However, in this case, the pair of end plates 32 of the cage 31 are fixed (for example, press-fitted and fixed) to the inner peripheral surface of the pulley 21.

In the first and second embodiments, the inner ring body of the one-way clutch 30 is the shaft body 11 and the outer ring body is the pulley 21. However, the inner ring body is formed separately from the shaft body 11. Thus, the outer ring body may be assembled to the outer peripheral surface of the shaft body 11, or the outer ring body may be formed separately from the pulley 21 and assembled to the inner peripheral surface of the pulley 21.
Further, in the first and second embodiments, the case where the pulley unit is provided with a one-way clutch corresponding to an alternator which is one of engine auxiliary machines is exemplified. However, the compressor for the air conditioner, the water pump, It can be used as a pulley unit provided with a one-way clutch corresponding to engine accessories such as a cooling fan, or a one-way clutch assembled to the pulley unit.
Further, the one-way clutch of the present invention can be adopted even with gears or sprockets other than the pulley unit.

It is a sectional side view which shows the pulley unit provided with the one way clutch which concerns on Example 1 of this invention. It is sectional drawing based on the II-II line of FIG. It is a top view which expands and shows the state in which the roller and the coil spring were similarly accommodated in the pocket of the holder | retainer. It is a side view which expands and shows the state in which the roller and the coil spring were similarly accommodated in the pocket of the holder | retainer. It is a top view which expands and shows the state by which the roller and the coil spring were accommodated in the pocket of the holder | retainer of the one-way clutch used for the pulley unit which concerns on Example 2 of this invention. It is a side view which expands and shows the state in which the roller and the coil spring were similarly accommodated in the pocket of the holder | retainer.

Explanation of symbols

11 Shaft (Inner ring)
21 Pulley (outer ring body)
30 One-way clutch 31 Cage 32 Pair of end plates 34 Pocket 35 Column 36 Projection 40 Roller 45 Coil spring 48, 148 Convex (contact)

Claims (3)

A one-way clutch that switches between a locked state in which an inner ring body and an outer ring body that are concentrically arranged inside and outside in a radial direction are synchronously rotated and a free state in which the inner ring body is relatively rotated,
A plurality of wedge-shaped spaces are formed at predetermined intervals in the circumferential direction between the opposed peripheral surfaces of the inner ring body and the outer ring body,
In the plurality of wedge spaces, the same number of rollers and coil springs individually energizing the rollers in the locking direction for engaging each of the rollers in the wedge-shaped spaces are arranged in a state of being accommodated in the pockets of the cage. And
As a contact portion that holds the roller in a tiltable manner on one surface of the opposing surfaces of the both axial end surfaces of the roller and the inner surfaces of both side walls in the axial direction of the pocket while being in point contact with the other surface. projections provided, et al are of
The one-way clutch , wherein when the roller is assembled in the pocket, the roller is elastically held by elastically deflecting both side walls of the pocket by the convex portion . The one-way clutch according to claim 1,
The convex portion of the contact portion, the one-way clutch, characterized in that it is protruded on both side walls the inner surface of the pocket of the cage. The one-way clutch according to claim 1,
The convex portion of the contact portion, the one-way clutch, characterized in that it is projected from the substantially central portion of the end surfaces of the roller.

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