JPH059653B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in one-way clutches.

Conventionally, two types of one-way clutches are known: a sprag type and a roller type.

A sprag type one-way clutch consisting of an outer ring with an annular inner surface, an inner ring with an outer surface arranged concentrically corresponding to this inner surface, and a plurality of sprags arranged in an annular space formed between these inner and outer surfaces. has been done. In this case, when the inner ring rotates in one direction, its upper and lower cam surfaces are inclined to positions where no torque is transmitted, allowing relative rotation between the inner ring and the outer ring. On the other hand, when the inner ring attempts to rotate in the other direction, the cam surface of the sprag moves and the sprag is inverted, preventing relative rotation between the inner and outer rings, so that torque is transmitted from the inner ring to the outer ring. There is.

On the other hand, a roller type one-way clutch has a configuration in which the roller is housed in a roller storage groove formed on either the inner ring or the outer ring, and is biased by a spring in a direction that narrows the distance between the groove bottom and the circumferential surface. When either the inner ring or the outer ring is driven in one direction, the rollers idle, and when they are driven in the other direction, the rollers roll in the housing groove and get caught between the groove bottom and the circumferential surface, causing the inner ring to It is designed to transmit torque by preventing relative rotation between the outer ring and the outer ring.

The conventional one-way clutch described above has a long service life as long as it is used with a load torque below a predetermined value, but if an accidental excessive torque is applied, the sprag or roller will move beyond the predetermined torque transmission position and When it tries to bite between the inner and outer rings, it may leave impressions on the contact surface between the inner and outer rings, or the sprags or rollers may become chipped or cracked. Further, in such a case, the roller may jump out to the non-torque transmission side, that is, to the side of the spring that urges the roller, and the spring may be damaged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a long-life one-way clutch that eliminates the above-mentioned drawbacks by allowing the sprag to slip stably during excessive torque loads.

The present invention provides an outer ring having an annular inner surface, an inner ring having a concentric annular outer surface corresponding to the outer ring, and an annular space disposed on one of the inner surface or the outer surface in the circumferential direction. a plurality of tiltable sprags and a retainer that holds the sprags, and the direction and angle of tilting of the sprags are determined by the direction of relative rotation and the torque difference generated between the inner ring and the outer ring. The sprag has a first surface portion that reduces its height when tilting in a first direction, and a first surface portion that reduces its height when tilting in a second direction at a tilt angle less than a predetermined angle. a second surface portion whose height gradually increases; and when an excessive torque is applied to tilt in the second direction and reach a predetermined angle, the second surface portion contacts at least one of the inner surface of the outer ring and the outer surface of the inner ring. When the inner ring and the outer ring rotate relative to each other in one direction, the sprag is tilted in the first direction, so that the inner ring, the outer ring, and the sprag The frictional force generated between the inner ring and the outer ring is reduced, and the torque transmission between the inner ring and the outer ring is stopped, and the inner ring and the outer ring are rotated relative to each other in the other direction. In this case, when the sprag tilts in the second direction at a tilting angle less than the predetermined angle, the inner ring, the outer ring, and the second sprag
The frictional force generated between the inner ring and the outer ring increases, and torque is transmitted between the inner ring and the outer ring, and the inner ring and outer ring rotate relative to each other in the other direction. In this case, when an excessive torque is applied and the sprag tilts in the second direction and reaches the predetermined angle, at least one of the outer surface of the inner ring and the inner surface of the outer ring and the substantially flat surface of the sprag By bringing these parts into contact with each other, the increase in frictional force between them is stopped, and if further torque is applied from this state, slipping will occur between the inner ring, the outer ring, and the sprag. Further, the thickness of the sprag increases in the circumferential direction by tilting in the second direction, and the cage is provided with a hole for holding the sprag, and the retainer is provided with a hole for holding the sprag to prevent excessive torque from being applied. When the sprags tilt in the second direction and try to exceed the predetermined angle, the thickness of each sprag in the circumferential direction increases within the hole, and the sprags come into contact with the holes almost simultaneously. Excessive tilting of the slider is prevented, and the sliding is performed stably. This configuration achieves the above objective.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 illustrate one embodiment of a sprag type one-way clutch according to the present invention. This one-way clutch has an annular outer ring 10
, an annular inner ring 20 arranged concentrically inside the outer ring 10 , a large number of sprags 30 arranged between them, and a holding means 40 for holding the sprags 30 .

The annular outer ring 10 has an annular inner surface 12 .
On the other hand, the annular inner ring 20 has an annular outer surface 22 that faces the inner surface 12 of the outer ring 10 . In this embodiment, the inner ring 20 is a torque transmission member that is engaged with a drive shaft (not shown), rotates together with the drive shaft, and transmits torque, and the outer ring 10 is arranged in one direction (first direction) of the inner ring 20.
It is a torque-transmitted member to which torque is transmitted by rotation only in the clockwise rotation direction (in the figure). Contrary to this embodiment, it is also possible to use the outer ring 10 as a torque transmitting member and the inner ring 20 as a torque transmitted member.

A large number of sprags 30 are arranged in the circumferential direction within an annular space 14 formed between the inner surface 12 of the outer ring 10 and the outer surface 22 of the inner ring 20. Each sprag 30 has cam surfaces 32 and 34 that abut on the inner surface 12 and the outer surface 22, respectively. The front and rear side surfaces 36 and 38 in the rotation direction that are connected to the cam surfaces 32 and 34 are
A holding means 40 which has a recessed portion in its center and will be described later.
is maintained by.

The cam surface 32 is formed of a curved surface having a single predetermined curvature centered at ₀₀ . On the other hand, the cam surface 34 is composed of a curved surface 34a having a predetermined curvature centered on a center _0i different from the center ₀₀ , and a flat surface 34b continuously connected to the curved surface 34a. center here
0 ₀ is in the direction in which the outer ring 10 is rotated (to the right in Fig. 2),
The center 0 _i is eccentric in the opposite direction to 0 ₀ (to the left in Figure 2). Centers 0 ₀ and 0 _i and each cam surface 32 and 3
The curvature of 4a is a value determined by the relationship between the magnitude of the transmitted torque and the distance J between the space 14 between the inner ring 20 and the outer ring 10, and this is a conventionally known technique.

An inflection point 34a' of the plane 34b from the curved surface 34a of the cam surface 34 is determined by the maximum transmitted torque.

The method of setting the inflection point 34a' and the plane 34b will be explained below using FIGS. 2 to 5.

In FIG. 3, the inner ring 20 and the sprag 30
Let A be a contact point with the outer ring 10 and a contact point B with the sprag 30, and the distance therebetween is the sprag height H. On the other hand, a line passing through the contact point A and extending outward from the rotation center 0 of the inner ring 20 and the outer ring 10 and the contact point A
The angle sandwiched by the line connecting B and B is the wedge angle θ.

In the case of the sprag shape shown in Fig. 2, the relationship between the sprag height H and the wedge angle θ is as shown in Fig. 4.
Non-torque transmission of cam surface 34 (i.e. curved surface 34a
As the sprag 30 rotates from the right end of the sprag in the direction of the torque transmission section (i.e., left rotation), the wedge angle θ gradually increases, and after passing the sprag height _H1 , the wedge angle θ increases rapidly. There is. In this case, a predetermined maximum torque is transmitted at the sprag height H ₁ , and this point is at the sprag 30 in FIG.
In this case, the inflection point 34a' is set from the curved surface 34a to the plane 34b. plane 34b
is formed to intersect at an angle of 90 degrees or more (preferably 97 degrees) with the line connecting the center _0i and the inflection point 34a'.

The retaining means 40 of the sprag 30 is disposed within the annular space 14 between the outer ring 10 and the inner ring 20, as shown in FIG. The holding means 40 includes a first annular holding member 42 disposed on the outer ring 10 side, a second annular holding member 44 disposed on the inner ring 20 side, and an annular biasing spring 46 disposed between them. It is made up of. First holding member 42, second holding member 4
4. Rectangular holes are provided at equal intervals on the circumference of each biasing spring 46, and the sprag 30 is held within these holes. Biasing spring 46
is the sprag 3 when the inner ring 20 is stopped or idling.
0 is biased near the bottom of the recesses provided in the side surfaces 36 and 38 of the sprag 30 to provide a moment in the direction of torque transmission (left rotation in FIG. 1).

In this embodiment, the holding means 40 is composed of a first holding member 42 and a second holding member 44, but in other embodiments, the holding member 40 includes a first holding member 42 and a second holding member 44.
Either one of the holding members 42 or 44 may be used, and a single holding member may be attached to the sprag 30.
It may be provided near the recessed portions of the side surfaces 36 and 38.

The operation of the sprag type one-way clutch having the above configuration will be explained below.

When the inner ring 20 is stopped, each component is in the state shown in FIG. In this diagram,
When the inner ring 20 rotates to the left, the sprag 30
rotates to the right, then the front and rear sides 36 of the sprag 30
and 38 come into contact with the first holding member 42 and the second holding member 44 as shown in FIG. 5, and are held in that position. The sprag height H at this position is the inner ring 2
Height J of the annular space between 0 and outer ring 10 (see Figure 3)
More sufficient (even considering the installation eccentricity of the outer and inner rings)
Since the inner ring 20 is set to be small, the inner ring 20 rotates relative to the outer ring 10, that is, it rotates idly.

On the other hand, when the inner ring 20 rotates to the right, the sprag 30 rotates to the left, the sprag height H of the cam surface 34a increases, and the sprag 30 finally meshes with the inner ring 20 and the outer ring 10. In this state, outer ring 1
0 rotates together with the inner ring 20, and the torque is applied to the inner ring 20.
This will further transmit the signal to the outer ring 10.

However, if the torque exceeds a predetermined value, the inner ring 20
When the sprag 30 is rotated to the right, the sprag 30 is rotated further to the left than the normal torque transmission position, and the cam surface 34 moves beyond the point 34a' giving the sprag height H of the curved surface 34a so that the flat surface 34b or a portion of those flat surfaces A point on the curved surface 34a comes into contact with the outer surface 22 of the inner ring 20.

Incidentally, the rectangular holes of the first holding member 42 and the second holding member 44 have an appropriate circumferential length that is slightly longer than the circumferential thickness of the sprag 30. Therefore, in the above-mentioned case, the sprag 30 changes its attitude by rotating slightly to the left from the torque transmission position, and the circumferential thickness of the sprag 30 in the hole increases, as shown in FIG. Front and rear sides 3 of sprag 30 as shown
8 and 36 come into contact with the edges of the rectangular hole, respectively. Furthermore, the rectangular hole is connected to the second holding member 4.
4, the sprags 30 are spaced at equal intervals in the circumferential direction, so that the sprags 30 are spaced at equal intervals, so that contact between the sprags and the edge is provided over the entire circumference of the one-way clutch. Since the sprags 30 are generated at the same time, the plurality of sprags 30 contact the second holding member 44 at the same time and are stably held in that position. Therefore, the frictional force generated between the inner ring 10 and outer ring 20 and the sprag 30 will not increase beyond a predetermined value even if, for example, excessive torque of the one-way clutch occurs, and therefore the friction will increase by the amount of increased torque. The force is insufficient, causing the sprag 30 to slide relative to the rotation of the inner ring 20. Since the behavior of the sprag 30 is very unstable near the critical value of the wedge angle as shown in FIG. 6, stable sliding cannot be expected unless there is contact between the holding member and the sprag. Note that in this embodiment, the edges of the rectangular holes of the first holding member 42 and the second holding member 44 are provided so as to constitute the restraining means, but the edges of the rectangular holes of either one of the holding members The same effect can be obtained even if only the edge is used as a restraining means and the sprag 30 is brought into contact with only the edge.

In the above embodiments, the flat part is set on the cam surface that contacts the inner ring of the sprag, but this flat part may also be set on the cam surface that contacts the outer ring of the sprag, or it can be set on both cam surfaces. You may do so.

As explained above, according to the present invention, the sprag is structured to slide when subjected to excessive torque exceeding a predetermined value, so that the sprag, inner ring, and outer ring are prevented from being destroyed or damaged. This eliminates the problem and provides a long-life one-way clutch.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing one embodiment of a sprag type one-way clutch according to the present invention, and FIG.
The figure is an enlarged front view of the sprag shown in Fig. 1, and Fig. 3 is an enlarged front view of the sprag shown in Fig. 1.
Figure 4 is a diagram showing the relationship between sprag height and wedge angle when the plug shown in Figure 2 is used, Figure 5 is a one-way clutch sprag and retention when the inner ring is idling. FIG. 6 is a front sectional view of the one-way clutch when the sprag is in a sliding state; FIG. [Explanation of symbols of main parts], 10...Outer ring, 1
2... Inner surface of outer ring, 20... Inner ring, 22... Outer surface of inner ring, 30... Sprag, 32... Outer ring side cam surface, 34... Inner ring side cam surface, 40... Holding means,
42...first holding member, 44...second holding member,
46...Biasing spring, H...Sprag height, θ...
...Wedge angle.

Claims (1)

[Scope of Claims] 1. An outer ring having an annular inner surface, an inner ring having a concentric annular outer surface corresponding to the outer ring, and a circular space formed on one of the inner surface or the outer surface. It has a plurality of tiltable sprags arranged in a direction, and a retainer that holds the sprags, and the direction of tilting and the tilting angle of the sprags are determined by the direction of relative rotation occurring between the inner ring and the outer ring. and a torque difference, wherein the sprag has a first surface portion that reduces its height when tilting in a first direction and a tilting angle less than a predetermined angle in a second direction. a second surface portion whose height gradually increases; and when an excessive torque is applied and tilts in the second direction and reaches a predetermined angle, at least one of the inner surface of the outer ring and the outer surface of the inner ring. When the inner ring and the outer ring rotate relative to each other in one direction, the sprag is tilted in the first direction so that the inner ring and the outer ring are in contact with each other. Frictional force generated between the sprag and the first surface portion is reduced, torque transmission between the inner ring and the outer ring is stopped, and the inner ring and the outer ring are moved in the other direction. In the case of relative rotation, when the sprag tilts in the second direction at a tilting angle less than the predetermined angle, the inner ring, the outer ring, and the second sprag rotate according to the tilting angle.
The frictional force generated between the inner ring and the outer ring increases, and torque is transmitted between the inner ring and the outer ring, and the inner ring and outer ring rotate relative to each other in the other direction. In this case, when an excessive torque is applied and the sprag tilts in the second direction and reaches the predetermined angle, at least one of the outer surface of the inner ring and the inner surface of the outer ring and the substantially flat surface of the sprag By bringing these parts into contact with each other, the increase in frictional force between them is stopped, and if further torque is applied from this state, slipping will occur between the inner ring, the outer ring, and the sprag. Further, the thickness of the sprag increases in the circumferential direction by tilting in the second direction, and the cage is provided with a hole for holding the sprag, and the retainer is provided with a hole for holding the sprag to prevent excessive torque from being applied. When the sprags tilt in the second direction and try to exceed the predetermined angle, the thickness of each sprag in the circumferential direction increases within the hole, and the sprags come into contact with the holes almost simultaneously. A one-way clutch that prevents excessive tilting of the clutch and ensures stable sliding.