JP2007263278A - One-way clutch and sprag for one-way clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variation in inclination angle generated in sprags. <P>SOLUTION: A one-way clutch comprises: an inner ring 5 having an outer cylinder face; an outer ring 1 disposed coaxially with the inner ring and having an inner peripheral cylinder face; a plurality of sprags 2 disposed between the cylinder surfaces; and an elastic member 3 urging each of the sprags 2 in an engaging direction. Movement in a circumferential direction in an annular space of each sprag is restricted by mutual contact between adjacent other sprags 2. In a surface of the sprag 2, at least contact portions with adjacent other sprags 2 are coated by DLC coating. Therefore, posture of the sprags 2 is smoothly changed so as to suppress variation in inclination angle. If one or both of idling-side contact faces B, E with respect to each of cylinder faces of each of cam faces 11, 12 is/are coated by DLC coating, abrasion generated in each of the cam faces 11, 12 is reduced so as to suppress variation in inclination angle generated in the srags 2 is suppressed furthermore. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-way clutch that switches between transmission and interruption of power on a power transmission path.

A one-way clutch is a directional coupling that transmits power when the rotational speed on the drive side is faster than the driven side, and reverses the rotational direction on the drive side, or the rotational speed on the driven side is greater than the drive side. If it becomes faster, the transmission of power is cut off.
In this type of one-way clutch, a sprag is interposed between the inner ring and the outer ring, and the sprag is engaged with and disengaged from the inner and outer rings in accordance with the relative movement of the inner and outer rings. There is a sprag type that transmits and blocks torque to the side.

  In the sprag type one-way clutch, for example, as shown in Patent Document 1 and Patent Document 2, a large number of sprags are arranged along the circumferential direction in an annular space between the inner and outer rings, and the sprag is a retainer or the like. Is held at a predetermined interval.

In this sprag, a plurality of cam surfaces corresponding to the outer peripheral cylindrical surface of the inner ring and the inner peripheral cylindrical surface of the outer ring are formed, and each cam surface is formed by the elastic force of a garter spring constituted by an annular coil spring. The sprags are urged in the direction of engaging with the corresponding cylindrical surfaces.
A pair of annular side plates in the direction connecting the inner and outer rings are provided on both sides in the axial direction of the sprags, and components such as the sprags, retainers, and garter springs are stored between the pair of annular side plates. Has been.
JP-A-8-14279 JP-A-8-42603

In addition, there is a one-way clutch having a configuration in which a retainer is omitted as a lower-cost one-way clutch.
As a one-way clutch that does not include this type of retainer, for example, based on FIG. 1 that is an explanatory diagram of an embodiment of the present invention, an axis perpendicular to the axis of the sprag 2 (the axial direction of the one-way clutch C). The cross section is formed in an asymmetric barrel shape having convex and curved cam surfaces 11 and 12 with upper and lower end surfaces protruding outward. Torque is transmitted between the inner ring 5 and the outer ring 1 with the cam surfaces 11 and 12 standing upright in the circumferential direction (the distance between the contacts of the cam surfaces 11 and 12 with the inner surface of the outer ring 1 is relatively large). Accordingly, as the sprag 2 inclines in the circumferential direction, the inner ring 5 slides with respect to the outer ring 1, and the transmission of torque is interrupted (the chain line state in FIG. 3).

At the time of transmission, each sprag 2 has its lower side face in contact with the lower side face of another adjacent sprag 2, and an excessive torque in the engagement direction (direction of arrow f ₁ ) acts on the sprag 2. When the rotational force due to the above acts on the contact surface, the two sprags 2 and 2 that contact each other try to rotate in opposite directions (reaction force in the opposite direction acts), become locked and do not fall any further. ing.
As a result, the engagement / disengagement of the sprag 2 with the outer ring 1 is stabilized and the clutch operation is performed smoothly. Further, the adjacent sprags 2 and 2 come into contact with each other, whereby each sprag 2 is connected to the inner / outer ring 5. , 1 are equally arranged along the circumferential direction in the annular space, and the adjacent sprags 2, 2 come into contact with each other, so that each sprag 2 has an annular shape between the inner and outer rings 5, 1. It is equally divided along the circumferential direction in the space.

  In a one-way clutch that does not include this type of retainer, depending on the sprag attachment posture, the sprag may move in the circumferential direction due to the influence of its own weight or the like, and the equally divided arrangement may not be maintained.

If the sprags are not evenly arranged, the sprags repeatedly change their postures of engagement (locking) and disengagement (idling), thereby causing variation in the tilt angle of the sprags.
This variation tends to become prominent especially when the friction coefficient of the contact portion of the sprag surface with the other adjacent sprags is large. In such a state, there is a risk of adversely affecting full fading. is there.

  Further, among the cam surfaces of the sprag, the frictional coefficient of the contact surface (opposite surface) to the idle contact side with respect to each cylindrical surface of the inner and outer rings, that is, the contact surface (opposite surface) to each cylindrical surface when the sprag is in the idling posture. In addition, the drag torque increases and the wear generated on the contact surface increases, which is also not preferable because it leads to a significant variation in the tilt angle generated in the sprags.

  In view of this, an object of the present invention is to suppress the variation in the tilt angle generated in the sprags.

  In order to solve the above problems, the present invention includes an inner ring having an outer peripheral cylindrical surface, an outer ring having an inner peripheral cylindrical surface disposed coaxially with the inner ring and facing the outer peripheral cylindrical surface, and the outer periphery. A plurality of sprags disposed in an annular space between a cylindrical surface and the inner peripheral cylindrical surface and having a plurality of cam surfaces corresponding to the outer peripheral cylindrical surface and the inner peripheral cylindrical surface; Each cam surface includes an elastic member that biases each sprag in a direction in which the cam surface engages with the outer peripheral cylindrical surface and the inner peripheral cylindrical surface, and each sprag is formed into the annular shape by mutual contact with another adjacent sprag. In a one-way clutch in which movement in the circumferential direction in the space is restricted, a structure in which a diamond-like carbon coating is applied to at least a contact portion of the surface of the sprag with a neighboring sprag. It was adopted.

A diamond-like carbon coating (hereinafter referred to as “DLC coating”) is known to be amorphous because it has a very smooth surface and a low coefficient of friction. For this reason, by applying DLC coating to the contact portion of the sprag surface with another adjacent sprag, the sprag posture change can be smoothed and the variation in the tilt angle can be suppressed.
The DLC film formed by DLC coating is a general term for amorphous carbon films in which carbon is arranged like a diamond crystal, and has a low friction coefficient and wear resistance and adhesion resistance over a long period of time. It is rich and has the characteristics of low aggression. In addition, since it has high chemical stability, it can withstand use in a corrosive atmosphere. Further, since the base material can be directly coated and no special pretreatment is required, the film can be formed at low cost. The DLC film can be coated on a product using various well-known thin film forming techniques such as ion spraying, plasma CVD, and ion beam adhesion.

  Moreover, the following structure can be employ | adopted as another means. That is, an inner ring formed with an outer peripheral cylindrical surface, an outer ring formed coaxially with the inner ring and formed with an inner peripheral cylindrical surface facing the outer peripheral cylindrical surface, and between the outer peripheral cylindrical surface and the inner peripheral cylindrical surface A plurality of sprags arranged in an annular space and having a plurality of cam surfaces corresponding to the outer peripheral cylindrical surface and the inner peripheral cylindrical surface; and the cam surfaces abutting on the sprags and elastically acting on the cam surfaces An elastic member that urges each sprag in a direction to engage with the circumferential cylindrical surface, and each sprag is restricted from moving in the circumferential direction in the annular space by mutual contact with another adjacent sprag. In the one-way clutch, at least one or both of the idling side contact surfaces of the cam surfaces with respect to the cylindrical surfaces among the surfaces of the sprags are provided with dalc coating.

  As described above, DLC coating is a general term for an amorphous carbon film mainly composed of carbon and hydrogen, and its hardness is close to that of diamond. For this reason, by applying DLC coating to one or both of the idling side contact surfaces of the cam surfaces of the sprags, the hardness of the contact surfaces can be increased and the wear resistance can be improved. As a result, wear that occurs on the contact surface is reduced, and variation in the tilt angle that occurs in the sprags can be suppressed.

  The DLC coating may be applied to one or both of the contact surfaces of the cam surfaces with respect to the cylindrical surfaces in addition to contact portions with other adjacent sprags. good.

  In the present invention, since the DLC coating is applied to at least one of the sprag surfaces in contact with the adjacent sprags, or one or both of the idling contact surfaces of the cam surfaces, variation in the tilt angle generated in the sprags is achieved. Can be suppressed.

1 to 3 show an embodiment of the present invention, FIG. 1 is a front view, FIGS. 2A, 2B, and 2C are enlarged views of main parts of different embodiments, and FIG. 3 is an operational view of a sprag. Indicates.
Since the function of the one-way clutch C is the same as that of the conventional example, the description thereof will be omitted, and the movement of the sprag 2 will be described below.

First, the outer ring 1 is the driving side, when the inner ring 5 is driven, if the rotational force arrow -f ₁ direction of the outer ring 1 becomes a direction to upright sprags 2 from the chain line state to the solid line position shown in FIG. 3 , Thus, the inner ring 5 of the clutch C is stationary engaged rotated in the same direction (direction of arrow f _2).
On the other hand, if the rotational force to the outer ring 1 is in the opposite direction, the sprags 2 are tilted in the opposite direction against the elastic force of the elastic member 3, so that the solid line state shown in FIG. The sprags 2 are inclined from the upright state, the rotational force is not transmitted to the inner ring 5, and the clutch is turned off (disengaged).

Next, when the inner ring 5 is on the driving side and the outer ring 1 is on the driven side, the clutch C is engaged if the rotational force applied to the inner ring 5 is in the direction of the arrow f _{1 in} a completely opposite relationship. If the outer ring 1 that is stationary is rotated in the same direction (the direction of the arrow -f ₂ ) and the rotational force to the inner ring is the opposite direction (the direction of the arrow f ₂ ), the rotational force to the outer ring 1 is transmitted. In other words, the clutch is turned off (disengaged).

On the surface of the sprag 2, as shown in FIGS. 1 and 2A, a DLC coating layer _RA is provided at a contact portion with another adjacent sprag (2).
For this reason, the surface of the sprag 2 where the DLC coating layer _RA is provided has higher wear resistance than the base material surface of the sprag 2 and the friction coefficient of the surface is low. It has become a thing.

When an excessive torque in the direction of engagement (f ₁ arrow) is applied, the sprags 2, as shown in FIG. 3, in contact with the lower side surface D of the other sprags 2 in which the lower side surface A is adjacent, The sprag 2 is restricted from rotating so that it will be locked and will not fall further.
At this time, since the friction coefficient of the sprag mutual contact portion is reduced by the DLC coating layer _RA , it is possible to prevent both from being completely engaged and to move, and to return from the locked state to the idling direction. Is smooth. For this reason, the attitude | position change of a sprag is smoothed and the dispersion | variation in the fall angle between each sprag 2 is suppressed.
Further, the provision of the DLC coating layer _RA improves the wear resistance of the contact portion. For this reason, the abrasion accompanying the contact between the sprags 2 is reduced.

In addition to the DLC coating layer _RA , the location where the DLC coating is applied is shown in FIG. 2B on the idle side contact surface B with respect to the cylindrical surface of the inner ring of the cam surfaces 11 and 12 of the sprag 2. as it may be subjected to DLC coating layer _{R B.}
Furthermore, as shown in FIG. 2 (c), of the cam surfaces 11 and 12 of the sprags 2, the idling side contact surface E against the cylindrical surface of the outer ring 1 may be subjected to DLC coating layer _{R E.}
DLC coating layer R _B, by providing the DLC coating layer R _E, is improved wear resistance of the respective cylindrical surfaces of the sprags 2 and the inner and outer rings during idling. For this reason, wear on the cam surfaces 11 and 12 of the sprag 2 is reduced, and drag torque is reduced to facilitate the posture change of the sprag 2, and as a result, the variation in the tilt angle between the sprags 2 is further increased. It is suppressed.

  Moreover, you may provide a DLC coating layer in the contact part D with the adjacent other sprags 2 shown in FIG. 3 among the surfaces of the sprags 2, and if necessary, out of the cam surfaces 11 and 12 of the sprags 2 A DLC coating layer may be provided on the engagement side contact surface C with respect to the cylindrical surface of the inner ring.

The partially cut front view which shows the one-way clutch of one Embodiment 1 is an enlarged view of the main part of FIG. Enlarged view of the main part showing the action of sprags

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Sprag 3 Elastic member 4 Groove 5 Inner ring 11 Outer ring side cam surface 12 of sprag Inner ring side cam surface R _A , R _B , R _E DLC coating layer C of sprag One-way clutch

Claims (4)

An inner ring (5) formed with an outer peripheral cylindrical surface, an outer ring (1) formed coaxially with the inner ring (5) and formed with an inner peripheral cylindrical surface facing the outer peripheral cylindrical surface, the outer peripheral cylindrical surface and the A plurality of sprags (2) disposed in an annular space between inner peripheral cylindrical surfaces and having a plurality of cam surfaces (11, 12) corresponding to the outer peripheral cylindrical surface and the inner peripheral cylindrical surface, and each sprag (2) And an elastic member (3) for urging the sprags (2) in a direction in which the cam surfaces (11, 12) engage with the outer peripheral cylindrical surface and the inner peripheral cylindrical surface by elastic force. In the one-way clutch, each sprag (2) is restricted from moving in the circumferential direction in the annular space by mutual contact with another adjacent sprag (2).
A one-way clutch characterized in that a diamond-like carbon coating is applied to at least a contact portion between the surface of the sprag (2) and another adjacent sprag (2). An inner ring (5) formed with an outer peripheral cylindrical surface, an outer ring (1) formed coaxially with the inner ring (5) and formed with an inner peripheral cylindrical surface facing the outer peripheral cylindrical surface, the outer peripheral cylindrical surface and the A plurality of sprags (2) disposed in an annular space between inner peripheral cylindrical surfaces and having a plurality of cam surfaces (11, 12) corresponding to the outer peripheral cylindrical surface and the inner peripheral cylindrical surface, and each sprag (2) And an elastic member (3) for urging the sprags (2) in a direction in which the cam surfaces (11, 12) engage with the outer peripheral cylindrical surface and the inner peripheral cylindrical surface by elastic force. In the one-way clutch, each sprag (2) is restricted from moving in the circumferential direction in the annular space by mutual contact with another adjacent sprag (2).
Of the surface of the sprag (2), at least one or both of the idling side contact surfaces (B, E) of the cam surfaces (11, 12) with respect to the cylindrical surfaces are provided with a diamond-like carbon coating. And one-way clutch.   The one-way clutch according to claim 1, wherein a diamond-like carbon coating is applied to one or both of the idle contact surfaces (B, E) of the cam surfaces (11, 12) of the sprags (2) with respect to the cylindrical surfaces. A one-way clutch characterized by having been applied.   A sprag (2) for use in a one-way clutch, wherein the sprag (2) has a diamond-like carbon coating on the surface thereof.

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