JPH1082435A - Two-ways clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a low temperature engaging characteristic in a two-way clutch. SOLUTION: In a twoways clutch, plural sprags 3 having cam surfaces 14, 15 in periphery direction both sides and diameter direction both sides are installed so as to erect and slant-move freely between the outer periphery surface of a rotary shaft 2 and the inner periphery surface of an input gear 1 and a rotation torque is intercepted between the rotary shaft 2 and the input gear 1 by erecting of the sprag 3 and the rotation torque is transmitted between the rotary shaft 2 and the input gear 1 by the slant-moving of the prescribed amount of the sprag 3. The cam surfaces 14, 15 of the sprag 3 are composed of a torque transmission area for transmitting the rotation torque after pressure connecting to the outer periphery surface of the rotary shaft 2 and the inner periphery surface of the input gear 1 by the slant-moving of the prescribed amount of the sprag 3 and a standby area for shifting from a torque intercept state to a transmission state gradually in response to the slant-moving of the sprag 3 and a swelled part 16 is formed in the standby area of the cam surfaces 14, 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-way clutch, and more particularly, to a two-way clutch for switching transmission / disconnection of rotational torque in two directions by engaging / disengaging a sprag interposed between an inner ring and an outer ring.

[0002]

2. Description of the Related Art A conventional two-way clutch includes, for example, a plurality of sprags, which are torque transmitting members having cam surfaces formed on inner and outer portions, between an outer ring as an input member and an inner ring as an output member. Placed along the circumferential direction, each sprag,
There is one having a structure that can be engaged with and disengaged from a peripheral surface of an inner and outer ring while being held by an outer retainer and an inner retainer interposed between the inner and outer rings.

[0003] In this two-way clutch, in the neutral state where the sprags stand upright between the inner and outer wheels, the cam surface of the sprags is disengaged from the peripheral surfaces of the inner and outer wheels, whereby the rotational torque from the outer wheel as the input member is reduced. Cut off. On the other hand, when the sprag tilts by a predetermined amount due to the differential rotation of the inner cage with respect to the outer cage, the cam surface of the sprag presses and engages with the peripheral surface of the inner and outer races, whereby the rotational torque from the outer race as the input member is increased. Is transmitted to the inner ring, which is an output member, via a sprag.

[0004]

By the way, the aforementioned 2
When the directional clutch is used at a low temperature, switching from torque interruption to torque transmission may not be performed smoothly. This is because a thick oil film is formed between the peripheral surface of the inner and outer rings and the cam surface of the sprag due to the decrease in the viscosity of the lubricating oil, and the cam surface of the inner and outer rings in the region (standby region) before shifting to the torque transmission region. It is considered that there is a cause for slipping on the peripheral surface.

[0005] Therefore, in order to improve the low-temperature engagement characteristics, various factors should be improved so that the cam surface of the sprag, particularly the standby area, tends to be boundary lubricated with the peripheral surfaces of the inner and outer rings. Factors for improving the low-temperature engagement characteristics include lowering the viscosity of the lubricating oil, decreasing the engagement speed, and increasing the surface pressure at which the oil film is cut.

Therefore, the present invention increases the above-mentioned factor, that is, the surface pressure at which the oil film is cut, by increasing the surface pressure so that the cam surface of the sprag tends to be boundary lubricated with respect to the peripheral surfaces of the inner and outer rings as described above. An object is to improve the meshing characteristics.

[0007]

SUMMARY OF THE INVENTION As a technical means for achieving the above object, the present invention relates to a cam surface between an outer peripheral surface of an inner ring and an inner peripheral surface of an outer ring on both circumferential sides and both radial sides. A plurality of sprags having a two-way clutch are arranged so as to be able to stand up and tilt freely, interrupt the rotation torque between the inner and outer wheels by standing up the sprags, and transmit the rotation torque between the inner and outer wheels by tilting the sprags by a predetermined amount. The cam surface of the sprag has a torque transmission region for transmitting rotational torque by pressing against the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring by a predetermined amount of tilting of the sprag, and a torque interruption with the tilting of the sprag. And a standby area for gradually shifting from the state to the torque transmission state, wherein the cam surface has a raised portion in the standby area.

[0008]

1 to 5 show an embodiment of the present invention.
And will be described.

The two-way clutch in the embodiment shown in FIGS. 1A and 1B has a rotating shaft 2 serving as an inner wheel [output member].
An input gear 1 which is an outer ring [input member] meshed with a gear on the engine side of the vehicle (not shown); and a plurality of sprags 3 interposed between the outer peripheral surface of the rotating shaft 2 and the inner peripheral surface of the input gear 1. The outer retainer 4 and the inner retainer 5 for storing and holding the sprags 3 interposed between the rotary shaft 2 and the input gear 1 are frictionally fixed to the inner retainer 5 by a retaining ring 7 via a disc spring 6. The friction plate 8 forms a main part.

A rolling bearing 9 is interposed between the outer periphery of the rotating shaft 2 and the inner periphery of the input gear 1, and a rolling bearing is provided between the outer periphery of the rotating shaft 2 and the inner periphery of the inner retainer 5. 10
Is interposed. An output gear 11 that meshes with an output gear (not shown) is spline-connected to the outer periphery of the rotating shaft 2. Further, the rotating shaft 2 has rolling bearings 12 and 13.
Thus, the casing is rotatably supported by a casing (not shown).
At least one claw portion 8a is integrally formed on the outer periphery of the friction plate 8 to be engaged with a concave portion such as a casing (not shown) in the rotational direction.

As shown in FIG. 2A, the sprag 3 has a substantially cocoon-shaped cross section orthogonal to the axis, and is provided on both sides in the circumferential direction of the outer diameter portion in contact with the inner circumferential surface of the input gear 1. The cam surface 14 has cam surfaces 15 on both sides in the circumferential direction of an inner diameter side portion in contact with the outer peripheral surface of the rotating shaft 2. The outer diameter side portion of the sprag 3 is formed in a pocket 18 [FIG.
The inner diameter side portion is accommodated in a pocket 19 (see FIG. 4) of the inner retainer 5 via a pair of leaf springs (not shown).

A feature of the present invention lies in the shape of the sprag 3. That is, as shown in FIGS. 2 (a) and 2 (b), raised portions 16 projecting from the reference surface a by a predetermined dimension are formed at both ends in the axial direction over the entire circumference including the cam surfaces 14 and 15 of the sprag 3. The reference surface a is a surface having a general size and shape of a sprag in this type of clutch.

FIG. 3 shows the contact state of the cam surface 15 with the rotating shaft 2 when the sprag 3 is tilted, and the contact state of the cam surface 14 with the input gear 1 is not shown.

The cam surface (14) 15 of the sprag 3 is in contact with the outer peripheral surface of the rotating shaft 2 (inner peripheral surface of the input gear 1) and the outer peripheral surface of the rotary shaft 2 by a predetermined amount of tilting of the sprag 3, thereby transmitting torque. The cam surface (14) 15 includes a region m and a standby region n in which a transition from a torque cutoff state to a torque transmission state is gradually performed as the sprag 3 tilts.
Has a raised portion 16 in the standby area n.

The protrusion of the raised portion 16 from the reference surface a is set so as to provide boundary lubrication in the standby area n of the cam surfaces 14 and 15. The present inventor has confirmed the effect with a protrusion size of about 10 μm, but this protrusion size is determined in consideration of the oil film formation thickness, switching response speed, etc. related to the operating temperature, lubricating oil viscosity, surface condition, and the like. May be set appropriately.

In the two-way clutch of the present invention, the sprag 3
Is in the neutral position, the sprag 3 is in the upright position as shown in FIG. 4 and separates from the inner peripheral surface of the input gear 1 and the outer peripheral surface of the rotary shaft 2 to cut off the rotational torque from the input gear 1. I do. On the other hand, when the sprag 3 is tilted in one of the forward and reverse rotation directions, the cam surfaces 14 and 15 are respectively brought into pressure contact with the inner peripheral surface of the input gear 1 and the outer peripheral surface of the rotary shaft 2 as shown in FIG. Thus, the rotational torque from the input gear 1 is transmitted to the rotating shaft 2 (and the output gear 11).

The above-described tilting of the sprag 3 is realized by the differential rotation of the inner retainer 5 with respect to the input gear 1 (and the outer retainer 4). That is, when the input gear 1 rotates, the outer retainer 4 rotates synchronously with the input gear 1. Here, the friction plate 8 is prevented from rotating with respect to the casing by the engagement of the claw portions 8 a, so that slippage occurs between the friction plate 8 and the inner retainer 5, and the inner retainer 5 receives a frictional force from the friction plate 8. As a result, the inner retainer 5 rotates differentially with respect to the input gear 1 and the outer retainer 4, and the sprags 3 tilt.

A cutout is provided on a part of the inner side of the outer retainer 4, and a stopper pin 17 is protruded from the cutout on the inner retainer 5 at a position facing the cutout. Therefore, the tilting of the sprag 3 is restricted by the differential rotation of the inner cage 5 until the stopper pin 17 of the inner cage 5 comes into contact with the notch end face of the outer cage 4 (see FIG. 1). You.

Here, the sprag 3 of the present invention has a raised portion 16 at a part of the standby area n of the cam surfaces 14 and 15, that is, at both ends in the axial direction of the sprag 3, as described above. When tilted (see FIG. 5),
A standby area n of the cam surfaces 14, 15 which gradually shifts from a neutral state to a pressure contact state in a torque transmission area m (see FIG. 3).
Then, only the raised portion 16 in the axial direction of the sprag 3 comes into contact with the inner peripheral surface of the input gear 1 and the outer peripheral surface of the rotating shaft 2.

As a result, the pressure receiving area on the inner peripheral surface of the input gear 1 and the outer peripheral surface of the rotary shaft 2 is reduced, so that the surface pressure by the sprags 3 is increased, and the inner peripheral surface of the input gear 1 and the outer peripheral surface of the rotary shaft 2 are increased. The oil film existing on the surface can be easily cut. Thereby, the transition from the standby area n to the torque transmission area m can be performed smoothly.

The torque transmission region m is weak to receive a large pressing force, but the standby region n is not subjected to a large pressing force, so that the cam surfaces 14 and 15 have a small set and the surface pressure is large. Can last. In the embodiment, the bulging portions 1 are provided at both ends of the sprag 3 in the axial direction.
Although 6 is provided, it may be provided at any position in the axial direction.

[0022]

According to the present invention, when the sprags are tilted by a predetermined amount, a torque transmission region for pressing the outer peripheral surface of the inner race and the inner peripheral surface of the outer race to transmit rotational torque, and a torque associated with the tilting of the sprags. On the cam surface of the sprag, which comprises a standby region for gradually shifting from the cut-off state to the torque transmitting state, by having a raised portion in the standby region of the cam surface, when the sprag is tilted, the sprag is moved to the standby region of the cam surface of the sprag. Since only the formed raised portion comes into contact with the peripheral surface of the inner and outer rings, the pressure receiving area can be reduced, the surface pressure can be increased, the oil film can be easily cut, and the low-temperature meshing characteristics can be improved. Can be easily realized.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view taken along line BB of FIG. 1B, showing an embodiment of a two-way clutch according to the present invention; FIG.
Sectional view along line AA in FIG.

FIG. 2A is a front view showing a sprag constituting a two-way clutch of the present invention, and FIG. 2B is a side view of FIG.

FIG. 3 is an enlarged sectional view of a main part showing a state in which an inner cam surface of a sprag contacts an outer peripheral surface of a rotating shaft.

FIG. 4 is a partially enlarged cross-sectional view showing a two-way clutch with a sprag in a neutral state.

FIG. 5 is a partially enlarged sectional view showing the two-way clutch in a state where the sprag is tilted.

[Explanation of symbols]

 Reference Signs List 1 outer ring [input gear] 2 inner ring [rotary shaft] 3 sprag 14 cam surface 15 cam surface 16 bulge m torque transmission area n standby area

Claims (1)

[Claims] 1. Between an outer peripheral surface of an inner ring and an inner peripheral surface of an outer ring,
A plurality of sprags having cam surfaces on both sides in the circumferential direction and on both sides in the radial direction are arranged so as to be able to stand up and tilt freely, the rotation torque is cut off between the inner and outer wheels by the uprightness of the sprags, and the inner and outer wheels are tilted by a predetermined amount of tilting of the sprags. A cam surface of the sprag, the cam surface of the sprag being pressed against the outer peripheral surface of the inner race and the inner peripheral surface of the outer race by a predetermined amount of tilt of the sprag to transmit the rotational torque. And a standby area for gradually shifting from a torque interrupted state to a torque transmitting state as the sprags tilt, and having a raised portion in the standby area on the cam surface thereof.