JP4136264B2 - One-way clutch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a one-way clutch having rollers as engaging elements, and more particularly to a one-way clutch suitable for a stator of a torque converter.
[0002]
[Prior art]
Generally, a one-way clutch having a sprag as an engaging member is used as a stator clutch of a torque converter used in an automatic transmission of an automobile. This clutch for the stator is engaged with a stator reaction force that changes the flow direction of the fluid returning from the turbine runner to the pump impeller in one direction by being locked to the stator shaft whose inner ring is a fixed shaft and the outer ring is a stator that is a rotating body. It is what is supported. For the fluid that flows back, low-viscosity oil called automatic transmission fluid is used.
[0003]
The sprag type one-way clutch is configured to turn on and off a clutch by raising and falling a plurality of sprags accommodated between inner and outer rings. For this reason, the sprag type one-way clutch is a normal roller type in which a plurality of rollers as engaging members accommodated between the inner and outer rings are moved in a direction to engage with the inclined cam surface to turn the clutch on and off. The amount of movement of the engagement element in the circumferential direction when the clutch is turned on and off is smaller than that of the direction clutch, so that more engagement elements can be arranged in the circumferential direction, and the torque capacity can be larger than that of the roller type. Therefore, a sprag type one-way clutch is often used as a stator clutch for a torque converter that is compact and requires a large torque capacity.
[0004]
However, in the sprag type one-way clutch, the height of the space between the inner and outer rings for accommodating the sprags is increased in order to raise the sprags, and the diameter dimension is larger than that of the roller type. In addition, since the sliding surface of the sprag with the inner and outer rings during idling is constant, there is a problem that it is more easily worn than the roller.
[0005]
On the other hand, as a one-way clutch with an increased torque capacity of a roller type, there is one disclosed in JP-A-47-43645. As shown in FIGS. 4 and 5, the one-way clutch has an inner shaft member so that the rollers 53 come into contact with each other between the inner peripheral surface of the outer hollow member 51 and the outer peripheral surface of the inner shaft member 52. 52, which is accommodated in a so-called full roller state, and each roller 53 is engaged with a plurality of inclined cam surfaces 54 provided on the inner peripheral surface of the outer hollow member 51 in one direction by a wedge effect. It is.
[0006]
The one-way clutch shown in FIG. 4 is accommodated in a state in which the rollers 53 surround the entire circumference of the inner shaft member 52, and these rotating members 53 when the outer hollow member 51 or the inner shaft member 52 rotates in the rotation direction. The roller 53 is engaged with the cam surface 54 by a frictional force between them. In this embodiment, when a frictional force acts on any one of the rollers 53, all the rollers 53 are engaged with the cam surface 54 by the engagement of the rollers 53.
[0007]
The one-way clutch shown in FIG. 5 is obtained by replacing one of the rollers 53 accommodated in the above-described full-roller state with a spring roller 55. The roller 53 that abuts on the spring roller 55 by the elastic force accompanying its elastic deformation is provided. By pressing, all the rollers 53 that are in contact with each other are engaged with the cam surface 54. In place of the spring roller 55, an elastic roller such as rubber or an elastic body such as a leaf spring may be used.
[0008]
These one-way clutches of the full roller type increase the torque capacity by increasing the number of rollers arranged, enable a compact design without the need for a roller cage, and reduce the cost.
[0009]
[Problems to be solved by the invention]
The conventional full-roller type one-way clutch described above has the following problems. That is, in the one-way clutch shown in FIG. 4, since the generation of the frictional force is unstable, the roller cannot be reliably engaged with the inclined cam surface, and the clutch may not work. On the other hand, in the one-way clutch of the type shown in FIG. 5, an elastic body such as a spring roller interposed between the rollers accommodated in the full roller state may be excessively contracted due to elastic deformation. There is a gap between them or between the elastic bodies, and the pressing force of the elastic bodies cannot be reliably and instantaneously transmitted to all the rollers. There is a problem of delay. Therefore, these one-way clutches cannot be adopted as a stator clutch for a torque converter that requires reliable on / off of the clutch.
[0010]
In order to solve the problems of the conventional one-way clutch of the above-mentioned general roller type, the present inventor invented the one-way clutch described in Japanese Patent Application No. 2000-34811. That is, this one-way clutch locks an elastic body by locking an elastic body that urges a roller as an engaging element in a direction to be engaged with a cam surface to an inner peripheral surface of the outer ring or an outer peripheral surface of the inner ring. All rollers housed in the full roller state can be kept in contact with each other directly or via auxiliary rollers, and the urging force of the elastic body can be reliably and instantaneously applied to all rollers. It can be transmitted to. Therefore, this one-way clutch basically satisfies strict clutch characteristics such as large torque capacity, compactness, and certainty of clutch on / off required for the above-mentioned torque converter stator clutch. If it can be used in clutches, a great merit can be obtained.
[0011]
Further, as described above, since the stator clutch of the torque converter is exposed to a low-viscosity automatic transmission fluid, there is a problem that even when the roller is used as an engagement element, the roller is easily worn during idling.
[0012]
Accordingly, an object of the present invention is to provide a full-roller type one-way clutch that has a large torque capacity, compactness and certainty of clutch engagement / disengagement that can be employed in a stator clutch of a torque converter and the roller is not easily worn. Is to provide.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the one-way clutch of the present invention has a plurality of inclined cam surfaces formed on the outer periphery, an inner ring having torque transmission means formed on the inner periphery, and a cylindrical surface formed on the inner periphery. An outer ring, a plurality of rollers housed between the cam surface and the cylindrical surface, and at least one elastic body mounted on the outer periphery of the inner ring and biasing the roller in a direction to engage the cam surface consists of a, the elastic body is loaded circumferential position, the interposed small diameter auxiliary rollers than rollers, wherein at each roller circumferential sides, either abut each other directly, or the auxiliary rollers A configuration is adopted in which the urging force of the elastic body is transmitted to all the rollers via the rollers that are in contact with each other.
[0014]
That is, torque transmitting means is formed on the inner periphery of the inner ring, a plurality of inclined cam surfaces are formed on the outer periphery, and at least one elastic body that urges the rollers in a direction to engage the cam surface is mounted. All rollers are kept in contact with each other either directly or via auxiliary rollers so that the urging force of the elastic body can be reliably and instantaneously applied to all rollers. To ensure high torque capacity, compactness and certainty of clutch on / off. The cam surface and the elastic body provided on the inner ring side are not affected by centrifugal force when the outer ring rotates, such as a stator clutch of a torque converter, and the idling characteristics are stabilized.
[0015]
As the elastic body, a steel plate spring having a tongue for pressing the roller can be adopted.
[0016]
The torque transmission means formed on the inner periphery of the inner ring can be an uneven surface.
[0017]
By integrally forming the torque transmission means on the outer periphery of the outer ring, the number of parts can be reduced and the assembling work of the clutch can be simplified.
[0018]
The torque transmission means formed on the outer periphery of the outer ring can be an uneven surface.
[0019]
By interposing the auxiliary roller at a position where the elastic body is locked, a large space for locking the elastic body is secured, and the urging force of the roller is increased by using a larger-sized elastic body. be able to.
[0020]
By forming innumerable independent minute depressions on the surface of the roller at random, a sufficient oil film is formed on the surface of the roller to reduce idling torque and to suppress wear due to sliding during idling. it can.
[0021]
When the surface of the roller in which the dents are randomly formed is represented by an average surface roughness by a least mean square RMS, the average surface roughness RMS (L) in the axial direction of the roller and the average surface roughness RMS in the circumferential direction. The ratio RMS (L) / RMS (C) to (C) is 1.0 or less, and the parameter SK value of the surface roughness is -1.6 or less in both the axial direction and the circumferential direction of the roller. Thus, an oil film is more easily formed with respect to the circumferential sliding of the roller, and the effect of suppressing wear due to sliding during idling can be further enhanced.
[0022]
The surface of the roller as described above can be formed by special barrel polishing. The parameter SK value represents the balance of the unevenness distribution of the surface roughness with respect to the reference surface, and becomes 0 when the unevenness is distributed symmetrically with respect to the reference surface, and the ratio of the recesses to the protrusions. As the number increases, the negative value increases. Therefore, by setting the SK value to −1.6 or less, it is possible to sufficiently provide a recess for holding the lubricating oil.
[0023]
By forming an annular groove on the inner peripheral cylindrical surface of the outer ring, it is possible to increase the lubricating oil retaining ability on the cylindrical surface and reduce idling torque.
[0024]
Each of the one-way clutches described above is incorporated into the stator of the torque converter, thereby ensuring excellent clutch characteristics and reducing costs.
[0025]
Embodiment
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. 1 and 2 show a first embodiment. The one-way clutch 1 is for a stator of a torque converter used in an automatic transmission of an automobile. As shown in FIGS. 1 (a) and 1 (b), a plurality of inclined cam surfaces 3 are provided on an outer peripheral surface of an inner ring 2. The rollers 5 are accommodated between these cam surfaces 3 and the inner peripheral cylindrical surface of the outer ring 4 so as to contact each other in the state of full rollers. Both the inner ring 2 and the outer ring 4 are made of sintered metal.
[0026]
Axial grooves 6 are provided at two locations on the outer peripheral surface of the inner ring 2, and steel plate springs 7 as elastic bodies are attached to the grooves 6, and the rollers 5 a abutting on the tongue pieces 7 a are cams. The pressing force of the tongue 7a is transmitted to all the rollers 5 by the contact of the rollers 5, and each roller 5 is engaged with the cam surface 3 in one direction. It is supposed to be combined. A small-diameter auxiliary roller 8 is interposed between the rollers 5a and 5b on both sides at the mounting position of each spring 7. Therefore, the urging force of each spring 7 toward the cam surface 3 and the engagement side is transmitted through the auxiliary roller 8 at the interposed portion of the auxiliary roller 8.
[0027]
The inner ring 2 is provided with a wide stepped portion on the inner peripheral side, and a serration 9 which is an unevenness as a torque transmitting means is formed on the inner periphery. As shown in FIG. To be fixed to the stator shaft 18. Further, the outer ring 4 is also formed with a plurality of protrusions 10 which are unevenness as torque transmitting means on the outer periphery, and is connected to the inner periphery of the stator 19 as a rotating body by the protrusions 10. Therefore, in the one-way clutch 1, when the inner ring 2 is fixed and the outer ring 4 rotates counterclockwise, all the rollers 5 are engaged by the cam surface 3, and the engagement is released by rotation in the opposite direction. Thus, the outer ring 4 idles together with the stator 19.
[0028]
An infinite number of independent dents are randomly formed on the surface of each roller 5, and the surface roughness is determined by the average surface roughness RMS (L) in the axial direction of the roller 5 and the average surface in the circumferential direction. The ratio RMS (L) / RMS (C) to the roughness RMS (C) is 1.0 or less, and the parameter SK value of the surface roughness is −1.6 in both the axial direction and the circumferential direction of the roller 5. It is as follows. Therefore, a sufficient oil film is formed with respect to the circumferential sliding of the roller 5, so that wear of the roller 5 due to sliding during idling is effectively suppressed, and idling torque is also reduced. Further, an annular groove 11 is formed on the inner peripheral cylindrical surface of the outer ring 4, and the lubricating oil retaining ability on this cylindrical surface is enhanced to reduce idling torque.
[0029]
FIG. 2 shows a state in which the one-way clutch 1 is incorporated in a torque converter 12 of an automatic transmission. The torque converter 12 includes a pump impeller 14 connected to an output shaft 13 of the engine, a turbine runner 16 disposed opposite to the pump impeller 14 and connected to an input shaft 15 of the transmission, a pump impeller 14 and a turbine runner. The stator 19 is disposed between the stator shafts 18 and fixed to the casing 17 via the one-way clutch 1.
[0030]
The stator 19 changes the flow direction of the fluid when returning the fluid recirculated between the pump impeller 14 and the turbine runner 16 formed in a bowl shape to the pump impeller 14 from the turbine runner 16 on the inner diameter side thereof. A forward rotational force is applied to the pump impeller 14 to amplify the transmission torque.
[0031]
As described above, the inner ring 2 of the one-way clutch 1 is fixed to the stator shaft 18 by the serration 9, and the outer ring 4 is coupled to the inner periphery of the stator 19 by the protrusion 10, and the stator 19 is in the fluid flow direction. Each roller 5 engages with the cam surface 3 to support this reaction force.
[0032]
3A and 3B show a reference example . In this one-way clutch, a plurality of inclined cam surfaces 22 are formed on the outer peripheral surface of the inner ring 21, and the rollers 24 are in contact with each other in a full roller state between these cam surfaces 22 and the inner peripheral cylindrical surface of the outer ring 23. Contained in contact. The inner ring 21 and the outer ring 23 are formed by punching a steel plate.
[0033]
An axial groove 25 is provided at one place on the outer peripheral surface of the inner ring 2, and a spring 26 made of a steel plate as an elastic body is attached to the groove 25, and the roller 24 a abutted on the tongue piece 26 a is connected to the cam surface 22. The urging force generated by the pressing of the tongue piece 26 a is transmitted to all the rollers 24 by the contact of the rollers 24, and each roller 24 is engaged with the cam surface 22 in one direction. It is like that.
[0034]
The inner circumference of the inner ring 21 is formed in a rectangular hole 27 having a rounded corner as torque transmission means, and the outer peripheral cylindrical surface of the outer ring 23 has chamfers 28 as torque transmission means at four positions with a phase of 90 °. Yes. In this one-way clutch, when the inner ring 21 rotates clockwise or the outer ring 23 rotates counterclockwise, all the rollers 24 are engaged with the cam surface 22, and in the case of rotation opposite to these, the rollers 24 are engaged. Is released.
[0035]
Similar to the first embodiment, innumerable independent minute depressions are randomly formed on the surface of each roller 24, and the surface roughness is equal to the average surface roughness RMS (L) in the axial direction of the roller 24. The ratio RMS (L) / RMS (C) to the average surface roughness RMS (C) in the circumferential direction is 1.0 or less, and the parameter SK value of the surface roughness is in the axial direction and circumferential direction of the roller 24. Both are below -1.6. An annular groove 29 is also formed on the inner peripheral cylindrical surface of the outer ring 23, so that an excellent wear suppression effect of the roller 24 and good idling characteristics can be obtained.
[0036]
The implementation described above, an elastic body for urging the rollers has been a steel spring, it is also possible to use a rubber, other elastic bodies. Moreover, as a torque transmission means formed on the inner periphery of the inner ring, a spline, a key groove, a notch, or the like can be employed.
[0037]
【The invention's effect】
As described above, the one-way clutch of the present invention forms torque transmitting means on the inner periphery of the inner ring, forms a plurality of inclined cam surfaces on the outer periphery, and urges the rollers in a direction to engage the cam surfaces. At least one elastic body is mounted, and the elastic body is not interposed between the rollers in the full roller state, so that all the rollers are always kept in contact with each other directly or via the auxiliary roller. Since the urging force can be transmitted to all rollers instantly and reliably, large torque capacity, compactness and certainty of clutch engagement / disengagement can be secured, and the cam surface and elastic body are provided on the inner ring side. In the case of outer ring rotation, such as a stator clutch for a torque converter, these are not affected by centrifugal force, and the idling characteristics can be stabilized.
[0038]
In addition, by forming innumerable independent minute depressions on the surface of the roller, a sufficient oil film is formed on the surface of the roller to reduce idling torque and suppress wear due to sliding during idling. Can do.
[0039]
When the surface of the roller in which the dents are randomly formed is represented by an average surface roughness by a least mean square RMS, the average surface roughness RMS (L) in the axial direction of the roller and the average surface roughness RMS in the circumferential direction. The ratio RMS (L) / RMS (C) to (C) is 1.0 or less, and the parameter SK value of the surface roughness is -1.6 or less in both the axial direction and the circumferential direction of the roller. Thus, an oil film is more easily formed with respect to the circumferential sliding of the roller, and the effect of suppressing wear due to sliding during idling can be further enhanced.
[0040]
Furthermore, by forming an annular groove on the inner peripheral cylindrical surface of the outer ring, it is possible to increase the lubricating oil retention capacity on this cylindrical surface and further reduce idling torque.
[Brief description of the drawings]
1 is a front view showing a one-way clutch according to the first embodiment; FIG. 1 is a side sectional view of a; FIG. 2 is a longitudinal sectional view showing a state in which the one-way clutch of FIG. Fig. 3a is a front view showing a one-way clutch of a reference example , b is a side sectional view of a, Fig. 4 is a partially omitted sectional view showing a conventional one-way clutch, and Fig. 5 is another conventional one-way clutch. Partially omitted cross-sectional view showing [signs]
1 one-way clutch 2 inner ring 3 cam surface 4 outer ring 5, 5 a, 5 b roller 6 groove 7 spring 7 a tongue piece 8 auxiliary roller 9 serration 10 ridge 11 annular groove 12 torque converter 13 engine output shaft 14 pump impeller 15 mission input shaft 16 Turbine runner 17 Casing 18 Stator shaft 19 Stator 21 Inner ring 22 Cam surface 23 Outer rings 24, 24a Roller 25 Groove 26 Spring 26a Tongue piece 27 Rectangular hole 28 Chamfer 29 Annular groove

Claims (5)

A plurality of inclined cam surfaces are formed on the outer periphery, an inner ring having torque transmission means formed on the inner periphery, an outer ring having a cylindrical surface formed on the inner periphery, and the cam ring is accommodated between the cam surface and the cylindrical surface. A plurality of rollers and at least one elastic body that is mounted on the outer periphery of the inner ring and urges the rollers in a direction to engage the cam surface, and in the circumferential position where the elastic body is mounted, by interposing a small-diameter auxiliary rollers than rollers, wherein at each roller circumferential sides, disposed is brought into contact with each other via whether to mutually abut directly, or the auxiliary rollers, the biasing force of the elastic member Is a one-way clutch which transmits all the rollers through the abutting rollers. The one-way clutch according to claim 1 , wherein innumerable independent minute depressions are randomly formed on a surface of the roller. When the surface of the roller in which the dents are randomly formed is represented by an average surface roughness as a least mean square RMS, the average surface roughness RMS (L) in the axial direction of the roller and the average surface roughness RMS in the circumferential direction. The ratio RMS (L) / RMS (C) with (C) is 1.0 or less, and the parameter SK value of the surface roughness is -1.6 or less in both the axial direction and the circumferential direction of the roller. Item 3. A one-way clutch according to item 2 . The one-way clutch according to any one of claims 1 to 3 , wherein an annular groove is formed on an inner peripheral cylindrical surface of the outer ring. The one-way clutch according to any one of claims 1 to 4 , wherein the one-way clutch is incorporated in a stator of a torque converter.

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