JP2000291755A - Power roller bearing for toroidal type continuously variable transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power roller bearing for a toroidal type continuously variable transmission device which can suppress the shortening of a life. SOLUTION: A power roller bearing 11 is used in a toroidal type continuously variable transmission device used for a transmission of an automobile or the like. The power roller bearing 11 comprises a power roller 10, outer ring 13, plurality of balls 12, holder 14, etc. The outer ring 13 and the power roller 10 are respectively formed in circular annular shape. Raceway grooves 15, 16 are formed in end surfaces 17, 18 opposed to each other of the outer ring 13 and the power roller 10. The raceway grooves 15, 16 are formed respectively in circular annular shape and in a circular arc-shaped section. Surfaces of the raceway grooves 15, 16 are applied with super-finishing and formed in 0.05 Ra or less surface roughness. Low friction layers 23, 24 are formed in the surfaces of the raceway grooves 15, 16, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power roller bearing of a toroidal-type continuously variable transmission used for transmissions for, for example, automobiles, general industries, and transportation equipment.

[0002]

2. Description of the Related Art Toroidal-type continuously variable transmissions used in transmissions for automobiles, general industries and transportation equipment include an input / output disk facing each other, a power roller provided between the input / output disks, and an input / output disk. A loading cam mechanism is provided for pressing at least one of the input and output disks in a direction in which the output disks are brought closer to each other.

An input disk is driven to rotate by a drive source such as an engine. The output disk transmits power based on the rotation of the input disk via a power roller or the like.

[0004] The power roller is swingably provided between an input disk and an output disk. The power roller has a traction portion that comes into contact with both disks. The power roller is supported in a state where its rotation is permitted by a power roller bearing as a thrust bearing.

The power roller bearing includes the above-described power roller as an inner ring, an outer ring, and a spherical ball as a rolling element rotatably provided between the outer ring and the power roller. The power roller is swingably provided between the input disk and the output disk by a trunnion. The power roller changes the transmission ratio of the toroidal-type continuously variable transmission by changing its inclination angle.

[0006] The member configuration of such a power roller bearing is almost the same as a thrust ball bearing used for supporting a rotating shaft on which a thrust load acts, except for the power roller.

Therefore, it has been studied to produce a power roller bearing of a toroidal type continuously variable transmission at low cost by diverting existing parts designed for a thrust ball bearing.

However, the appearance of the power roller bearing is very similar to that of a thrust ball bearing in appearance, but the function of the power roller as the inner ring is completely different from that of a general thrust ball bearing. Consider the differences in the load distribution acting on the power roller itself and the contact behavior between the outer ring and the power roller with the ball interposed between the outer ring and the power roller, as compared to general thrust ball bearings. These various improvements will be indispensable.

For example, the inner ring of a general thrust ball bearing is a shaft support member. In a power roller bearing, a power roller is a power transmission member for transmitting rotation from an input disk to an output disk, and is a multi-stage gear type. It corresponds to a transmission gear in a transmission. Since such a power roller is rotated at a high speed under a strong pressing force from an input disk or an output disk, it generates a large amount of heat, and the heat generated by the power roller heats a ball or the like.

Therefore, as the lubricating oil to be supplied between the outer ring and the power roller, it is essential to use a high-viscosity traction oil developed for the purpose of transmitting power.

Further, the traction portions of the power roller that come into contact with the input disk and the output disk are opposed to each other on the outer peripheral edge of the power roller by 180 degrees from each other. It acts intensively at the opposing position (traction section) as the resultant of the radial load and the thrust load. Therefore, a very high contact surface pressure is generated at the traction portion that comes into contact with the input disk or the output disk.

For example, a general bearing has a contact surface pressure of 2-3G.
On the other hand, in the case of a power roller bearing used for a toroidal type continuously variable transmission for a vehicle, the contact surface pressure is 2.5 to
It becomes 3.5 GPa, and the contact surface pressure may reach 4 GPa at the time of maximum deceleration.

Further, a strong pressing force from the input disk or the output disk is applied to the traction portion of the power roller.
A radial load is concentrated on the opposing position separated by 0 ° to cause radial deformation of the power roller.
Since the power roller is warped by the compression deformation, it is almost impossible to equally share the thrust load acting on the power roller to a plurality of balls interposed between the power roller and the outer ring. That is, the thrust load acting on the ball increases at a position shifted by 90 degrees from the contact position (traction portion) with the input or output disk,
As a result, the contact surface pressure of the ball against the raceway groove varies, and some balls roll on the raceway groove with an extremely high contact pressure.

Therefore, the traction portion which comes into contact with the input disk and the output disk, and the raceway grooves of the power roller and the outer ring which come into contact with the balls, are made of a material for preventing a reduction in the life due to a local action of a high contact surface pressure. In addition, special adjustment of surface hardness and surface roughness is indispensable.

[0015] From such a background, the applicant of the present application aims to improve the durability against the local action of the contact surface pressure and improve the bearing life, and therefore, the ball is formed of medium carbon steel or high carbon steel. A technique for adjusting the hardness and strength of the surface of a ball by carbonitriding or quenching and tempering has been proposed (see JP-A-7-208568).

[0016] The applicant of the present invention provides a grinding finish after carburizing the input disk and the output disk and a power roller in contact with them, or a grinding finish after carbonitriding. After the treatment, the hardness of the surface and the effective hardened layer depth of these members are adjusted to an appropriate value (4 mm at 2 mm or more) to withstand the action of local contact surface pressure.
mm or less).
No. 71555).

[0017]

However, a special traction oil is used as a lubricating oil to be supplied between the power roller and the outer ring, and the hardness and effective hardening of the power roller and the ball by selecting materials and surface treatment. Even if the depth of the layer and the surface roughness are adjusted, it is not enough.

In particular, the molecular structure of the traction oil, which is a synthetic oil, may be decomposed by the heat generated by the heat generated by the power roller. In this case, the traction coefficient is degraded, and the safety factor against gloss slip is also reduced. Also, it becomes difficult to form an oil film on the surfaces of the power roller and the balls, etc., and there is a possibility that the traction portion of the power roller and the surfaces of the raceway grooves of the power roller and the outer ring may peel off relatively early. Was. In this case, the life of the power roller bearing is reduced.

Since power transmission is the primary purpose of a power roller bearing, it is important to reduce the dynamic torque loss in the bearing as much as possible and to improve the torque transmission efficiency. In some cases, for example, depending on the dimensions of the raceway grooves and balls of the power roller and the outer ring, the dynamic torque loss in the bearing may increase and the torque transmission efficiency may decrease.

Even if the hardness of the surface of the power roller or the like and the depth of the effective hardened layer are adjusted, sometimes,
In some cases, problems such as shortening of the bearing life may occur due to early damage of the edge of the raceway groove or the ball, or damage to the contact surface between the raceway groove and the ball.

Accordingly, an object of the present invention is to provide a power roller bearing for a toroidal-type continuously variable transmission that can suppress a reduction in bearing life.

[0022]

In order to solve the above-mentioned problems and to achieve the object, a power roller bearing of a toroidal type continuously variable transmission according to the present invention comprises: an input disk which is rotationally driven by a drive source; In the power roller bearing of the toroidal-type continuously variable transmission that is swingably provided between the output disk and the output disk that is provided to face the outer ring,
A power roller rolling in contact with the input disk and the output disk, and a ball rotatably provided between the outer ring and the power roller, wherein both the outer ring and the power roller have an annular shape and an arc-shaped cross section. A raceway groove is formed and the ball rolls, and the raceway groove of the outer race and the raceway groove of the power roller are super-finished to have a surface roughness of 0.05R.
a, and a low friction layer is formed on at least one surface of the raceway groove of the outer race and the raceway groove of the power roller.

The power roller bearing of the toroidal-type continuously variable transmission configured as described above has a super-finished raceway groove for the outer ring and the power roller, and a surface roughness of 0.05 Ra.
A low friction layer is formed on at least one of the surface of the raceway groove of the outer ring and the surface of the raceway groove of the power roller.

For this reason, friction when the ball rolls in the raceway groove of the outer race and the raceway groove of the power roller can be suppressed, and the amount of heat generated at this time can be suppressed. Therefore, peeling is less likely to occur on the surface of the raceway groove, and a reduction in the life of the power roller bearing can be suppressed.

According to the present invention, the dynamic torque of the power roller bearing is reduced, and the power transmission efficiency of the entire toroidal type continuously variable transmission is improved. Thereby, when applied to an automobile, the effect of improving fuel efficiency can be obtained at the same time.

As the low friction layer, gold, silver, lead, molybdenum disulfide (MoS ₂ ), tungsten disulfide (W
S ₂ ), it is desirable to be composed of at least one of fluororesins. Among these, gold, silver, lead, and fluororesin are used to gradually scrape the lubricating substance from the original film forming surface due to the frictional force generated with the rotation of the bearing, and the scraped wear particles are transferred to the mating surface. Then, lubrication is performed by forming a thin film on the surface. On the other hand, molybdenum disulfide and tungsten disulfide form a layer and have a lubricating surface itself, so that the lubricating surface develops lubricity while being gradually worn. Molybdenum disulfide (MoS ₂ ), tungsten disulfide (W
S ₂ ) is formed on the surface of each of the raceway groove of the ball or the power roller and the raceway groove of the outer race by the sputtering process.

In these cases, it is possible to more reliably suppress the amount of generated heat and to suppress a reduction in the life of the power roller bearing.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG.

FIG. 1 is a sectional view showing a part of an automobile transmission 21 using a single-cavity half-toroidal stepless transmission 20 as a toroidal stepless transmission. FIG. 2 is a sectional view of the toroidal stepless transmission. FIG. 2 is a sectional view showing a power roller bearing 11 as a thrust bearing of the transmission 20.

As shown in FIG. 1, a single-cavity half-toroidal type continuously variable transmission 20 used for a transmission 21 for an automobile has an input shaft 1 rotated by a drive source E including an engine and the like, and an input disk 2. , An output disk 3, a power roller 10, and a loading cam mechanism 6 as a pressing means.

The input disk 2 is supported by the input shaft 1 and rotates in conjunction with the input shaft 1. Output disk 3
Is supported on the input shaft 1 so as to face the input disk 2. The output disk 3 rotates in conjunction with an output shaft that extracts power based on the rotation of the input shaft 1.

The power roller 10 is provided between the input disk 3 and the output disk 3 so as to be swingable, and comes into rolling contact with both disks 2 and 3. The loading cam mechanism 6 is provided on the back side of the input disk 2.

The loading cam mechanism 6 has a cam disk 4 and a cam roller 5. The cam disk 4
The spline engages with the input shaft 1 and rotates in conjunction with the input shaft 1. On a surface of the cam disk 4 facing the input disk 2, a cam surface 22 formed with irregularities along the circumferential direction is formed. The cam disk 4 rotates in conjunction with the drive source E.

The cam roller 5 is provided between the cam disk 4 and the input disk 2. The cam roller 5 is provided so as to be rotatable around an axis Q along the radial direction with respect to the axis P of the input shaft 1. A plurality of cam rollers 5 are arranged around the axis P of the input shaft 1.

With the above-described configuration, the loading cam mechanism 6 causes the cam surface 22 to rotate when the cam disk 4 rotates in conjunction with the driving source E including the engine.
Is pressed toward the input disk 2. Then, the input disk 2 is pressed via the cam roller 5 in a direction in which the input disk 2 and the output disk 3 approach each other. Also,
A pressing force generating mechanism such as a hydraulic piston may be used instead of the loading cam mechanism 6 as the pressing means.

A trunnion 8 is provided between the input disk 2 and the output disk 3. The trunnion 8 can swing about the pivot 7 in the direction indicated by the arrow R in FIG. A displacement shaft 9 is provided at the center of the trunnion 8. A power roller 10 is rotatably supported on the displacement shaft 9.

The power roller 10 is used for the input disk 2
And a traction portion 10a that comes into contact with the output disk 3
have. The power roller 10 changes the inclination angle between the input disk 2 and the output disk 3 according to the speed ratio of the toroidal-type continuously variable transmission 20.
The power roller 10 forms an inner ring of a power roller bearing 11 as a thrust bearing described later.

A power roller bearing 11 as a thrust bearing is provided between the trunnion 8 and the power roller 10. As shown in FIG. 2, the power roller bearing 11 includes the power roller 10 described above as an inner ring and the outer ring 1.
3. A ball 12 as a plurality of rolling elements and a retainer 14 are provided.

The outer ring 13 is formed in an annular shape and is supported by the trunnion 8. The balls 12 are each formed in a spherical shape. The balls 12 are provided so as to roll freely between the power roller 10 and the outer ring 13. Cage 1
4 is formed in an annular shape, and is provided between the outer ring 13 and the power roller 10. The retainer 14 holds the plurality of balls 12 so as to roll freely.

With the configuration described above, the power roller bearing 11 is provided between the input disk 2 and the output disk 3 so as to be swingable. When the loading cam mechanism 6 moves the input / output disks 2 and 3 toward each other,
, The rotational driving force of the input disk 2 rotated by the drive source E is transmitted to the output disk 3 via the power roller 10 and taken out as power.

The loading cam mechanism 6 presses the input disk 2 against the power roller 10 to push the input / output disks 2,
(3) When rolling contact with both, a load in the thrust direction is applied.
The power roller bearing 11 supports a load in the thrust direction applied to the power roller 10 from the input disk 2 and the output disk 3 and allows the power roller 10 to rotate.

As shown in FIGS. 3 and 4, the outer race 13 and the power roller 10 have raceway grooves 15 and 16 respectively formed on end faces 17 and 18 facing each other. The raceway grooves 15, 16 are formed in annular shapes on the end faces 17, 18, respectively. The raceway grooves 15 and 16 are each formed in an arc shape in cross section.

In the base material of each of the outer ring 13 and the power roller 10, the surfaces of the raceway grooves 15, 16 are super-finished. The raceway grooves 15 and 16 have a surface roughness of 0.0
It is formed to 5Ra or less. These track grooves 15,1
As shown in FIG. 3A and FIG. 4A, low friction layers 23 and 24 are formed on the surface of No. 6, respectively.

Also, a low friction layer 25 is formed on the surface of the ball 12 as shown in FIG. These low friction layers 23, 24, and 25 are made of gold, silver, lead, molybdenum disulfide (MoS ₂ ), tungsten disulfide (WS ₂ ), respectively.
It is composed of at least one of fluororesins.
Of these, the low friction layers 23, 24, 25 made of gold, silver, lead, and fluororesin are
The lubricating substance is lubricated by gradually scraping the above-mentioned lubricating substance from the original film forming surface, and transferring the shaved wear particles to a mating surface to form a thin film on the surface.

On the other hand, molybdenum disulfide (MoS ₂ ) and tungsten disulfide (WS ₂ ) are layered and have a lubricating surface itself, so that the lubricating surface develops lubricity while being gradually worn. It is. These molybdenum disulfide (MoS ₂ ) and tungsten disulfide (WS ₂ ) are sputtered to form the surface of the ball 12 and the raceway groove 1.
5 and 16 are formed on the respective surfaces.

According to the above-described configuration, the surfaces of the raceway grooves 15 and 16 of the outer race 13 and the power roller 10 are super-finished to form a surface roughness of 0.05 Ra or less, and the raceway grooves 15 and 16 are formed of respective surfaces. On the surface and the surface of the ball 12,
A low friction layer 23 made of molybdenum disulfide or the like,
24 and 25 are formed.

Therefore, the amount of heat generated when the ball 12 rolls in the raceway grooves 15 and 16 can be suppressed. Therefore, the surfaces of the raceway grooves 15 and 16 are less likely to be separated, and a reduction in the life of the power roller bearing 11 of the toroidal-type continuously variable transmission 20 can be suppressed.

In this embodiment, the low friction layers 23 and 24 are formed on both the surface of the raceway groove 15 of the outer race 13 and the surface of the raceway groove 16 of the power roller 10. 16, low friction layers 23, 24
May be formed. Also in this case, the reduction in the life of the power roller bearing 11 can be reliably suppressed.
As described above, by forming the friction layers 23 and 24 on at least one of the surface of the raceway groove 15 of the outer race 13 and the surface of the raceway groove 16 of the power roller 10, the toroidal-type continuously variable transmission 20 is formed. A reduction in the life of the power roller bearing 11 can be suppressed.

As described above, according to the present invention, the dynamic torque of the power roller bearing 11 is reduced, and the power transmission efficiency of the entire toroidal-type continuously variable transmission 20 is improved. Thereby, when applied to an automobile, the effect of improving fuel efficiency can be obtained at the same time.

[0050]

According to the power roller bearing of the toroidal type continuously variable transmission of the present invention, the surface of the raceway groove of each of the outer ring and the power roller is super-finished, the surface roughness is formed to be 0.05 Ra or less, and the outer ring A low friction layer is formed on at least one of the surface of the raceway groove and the surface of the raceway groove of the power roller. For this reason, the friction when the ball rolls is suppressed, and the amount of heat generated at this time is suppressed. Therefore, peeling is less likely to occur on the surface of the raceway groove, and a reduction in the life of the power roller bearing can be suppressed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a part of a single-cavity half-toroidal type continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is an exemplary sectional view showing the power roller bearing of the embodiment;

FIG. 3 is a diagram showing an outer ring of the power roller bearing according to the embodiment.

FIG. 4 is a view showing a power roller of the power roller bearing according to the embodiment.

FIG. 5 is a view showing a ball of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 2 ... Input disk 3 ... Output disk 10 ... Power roller 11 ... Power roller bearing 12 ... Ball 13 ... Outer ring 15 ... Raceway groove 16 ... Raceway groove 20 ... Single cavity type toroidal type continuously variable transmission (toroidal type continuously variable transmission) 23, 24, 25: Low friction layer

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Goto 1-50-5 Kugenuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (Reference) 3J051 AA03 BA03 BB02 BD02 BE09 CA05 CB07 EC03 ED20 FA02

Claims (1)

[Claims] 1. A power roller bearing of a toroidal type continuously variable transmission device which is swingably provided between an input disk which is rotationally driven by a drive source and an output disk provided opposite to the input disk. , An outer ring, a power roller that rolls in contact with the input disk and the output disk, and a ball that is rotatably provided between the outer ring and the power roller, wherein both the outer ring and the power roller are annular. And while having a raceway groove which is formed in an arcuate cross section and on which the ball rolls, the raceway groove of the outer ring and the raceway groove of the power roller have a surface roughness of 0.05 Ra or less by superfinishing, A power rod for a toroidal-type continuously variable transmission, wherein a low friction layer is formed on at least one surface of the raceway groove of the outer ring and the raceway groove of the power roller. La bearings.