JP2003343577A - Roller bearing and belt type non-stage transmission using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To lengthen the life of bearings while a misalignment between both pulleys on which a belt is wound is reduced in radial ball bearings for supporting a pulley shaft of a belt type non-stage transmission. <P>SOLUTION: An inner ring 1 and an outer ring 2 is made of a specific alloy steel (C: 0.10 to 0.90 mass %, CR: 3.0 to 8.0 mass %, Mn: 0.10 to 2.0%, Si: 0.10 to 1.0 mass %). The total content of carbon and nitride of a track surface is set to 1.20 mass % or higher and 2.50 mass % or lower. The remaining amount of austenite is set to 15 to 40 volume %. The surface hardness of the track surface is set to HRC59 to 64. Ri/D is set to 50.1 to 51.9% and Re/D is set to 50.1 to 51.9%. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing for supporting a pulley shaft of a belt type continuously variable transmission of a vehicle.

[0002]

2. Description of the Related Art A belt type continuously variable transmission of a vehicle has a mechanism for continuously changing the radius of a belt driven pulley as a transmission mechanism of an automatic transmission. For example, as shown in FIG. 4, pulleys 7 and 8 are provided on an input shaft (drive shaft) 5 and an output shaft (driven shaft) 6 arranged in parallel, and a metal belt 9 is provided between these pulleys. It's wrapped around.
This belt 9 has a structure in which a large number of thin friction pieces (having a thickness of about 2 mm) 92 are attached to a two-ring ring 91 having a structure in which about 10 thin plates having a thickness of about 0.2 mm are stacked. Power is transmitted by the pressing force when the friction pieces 92 press each other.

A driving force is transmitted from the input shaft pulley (primary pulley) 7 to the output shaft pulley (secondary pulley) 8 via the belt 9. Both pulleys 7 and 8 are
Fixed conical plates 71, 81 fixed to the respective shafts 5, 6 and movable conical plates 72, 82 movable in the axial direction by a hydraulic mechanism.
And the conical plates form a V-shaped pulley groove.

Each movable conical plate 7 of these pulleys 7 and 8
The gear ratio can be changed steplessly by moving 2, 82 in the axial direction to change the groove width and change the position where the belt 9 contacts the pulleys 7, 8 (effective rotation radius of the pulley). For example, if the groove width of the input shaft pulley is reduced and the groove width of the output shaft pulley is increased, the effective rotation radius of the input shaft pulley becomes smaller and the effective rotation radius of the output shaft pulley becomes larger, resulting in a large gear ratio. can get.

Shaft parts (pulley shafts) 71a, 81a, in which the fixed conical plates 71, 81 of the pulleys 7, 8 are integrated, are supported by radial ball bearings 11, 12. These pulley shafts 71a and 81a receive a thrust load as a reaction force when transmitting the shaft output to the subsequent stage. Therefore, it is possible to prevent the radial ball bearings 11 and 12 from axially displacing due to the thrust load so that the centers of the input shaft pulley and the output shaft pulley in the groove width direction are displaced (so-called “center misalignment” occurs). There is a need. If the misalignment becomes large, the belt 9 may meander and the ring 91 and the friction piece 92 may come into contact with each other improperly, resulting in damage. Also, the radial ball bearings 11 and 12 may slip and generate heat. It may grow.

As a countermeasure against it, Japanese Patent Publication No. 8-30526 discloses a ball bearing that supports a pulley shaft, and a ball diameter (D) of a radius of curvature (R) of raceway grooves of an inner ring and an outer ring.
The ratio (R / D) to the normal standard setting value (0.5
Smaller than 3) (50.1-50.9 in the inner ring)
%, And 50.1 to 51.9% for the outer ring).
As the ratio (R / D) is smaller, the ball bearing is less likely to be displaced in the axial direction by the thrust load, so that the above-mentioned misalignment between the pulleys is less likely to occur.

Further, Japanese Unexamined Patent Publication No. 10-292859 describes the use of a four-point contact ball bearing in which the amount of retained austenite in the inner ring and balls is 5% or less. Here, by setting the amount of retained austenite to 5% or less, the dimensional change due to the decomposition of the retained austenite during heat generation is reduced. On the other hand, the lubricating oil for the belt type continuously variable transmission includes a ball bearing that supports the pulley shaft in order to smoothly operate a torque converter, a gear mechanism, a hydraulic mechanism, a wet clutch, etc. to transmit power. , Traction oil (with a traction coefficient of 0.09 or more and a kinematic viscosity at 40 ° C. of 30.8 × 10 ⁻⁵ m ² / s (3
0.8 cSt) or more, and a lubricating oil containing a special wear modifier and the like) is used.

[0008]

SUMMARY OF THE INVENTION Here, Japanese Patent Publication No. 8-3
When the ratio (R / D) is reduced as in the method of Japanese Patent No. 0526, the contact area between the raceway groove and the ball is increased and the surface pressure is reduced, so that the bearing life is expected to be extended. However, it has been found that in a radial ball bearing lubricated with traction oil, it is difficult to obtain the expected long life by a method of reducing the surface pressure. It is presumed that the reason is that the peeling form is different when the lubricating oil is traction oil and when it is mineral oil.

That is, when the lubricating oil is mineral oil, as shown in FIG.
As shown in (a), the position of the separation starting point is at the center of the groove width direction of the raceway groove, whereas in the case of traction oil, as shown in FIG. It is often located off the center in the width direction. This position is a position where the rotational speed difference V between the bearing ring and the ball is large, and it is considered that not only the surface pressure P between the bearing ring and the ball but also the rotational speed difference V has some influence on the bearing life. . Then, reducing the ratio (R / D) leads to easier contact of the ball with a position deviated from the center of the raceway groove in the groove width direction.

Therefore, in the case of a radial ball bearing that supports the pulley shaft of a belt type continuously variable transmission, the ratio (R /
Only the method of reducing D) cannot achieve both the purpose of reducing the misalignment between the pulleys and the purpose of increasing the bearing life. In addition, it is conjectured that the cause of the short life of the rolling bearing that supports the rotary shaft of the pulley of the belt type continuously variable transmission is as follows.

That is, in the rolling bearing for the above-mentioned application, not only slippage due to the above-mentioned misalignment between the pulleys but also slippage and vibration due to stick-slip friction generated in the metal belt wound between the pulleys, and therefore, the lubricating film Is particularly easily peeled off. As a result, in this bearing, heat generation and surface fatigue due to metal contact are likely to occur, and a new surface is likely to occur on the raceway surface. Then, it is considered that the newly formed surface acts as a catalyst to decompose hydrocarbons and water in the lubricating oil to generate hydrogen and specifically cause early peeling.

The present invention has been made to solve the problems of the prior art, and in a radial ball bearing that supports the pulley shaft of a belt type continuously variable transmission, the core between both pulleys around which the belt is wound. The purpose is to extend the life of the bearing while reducing the deviation.

[0013]

To achieve the above object, the present invention provides a rolling bearing in which a plurality of rolling elements are rotatably arranged between an inner ring and an outer ring, and an inner ring, an outer ring, and At least one of the rolling elements is a mass ratio,
Carbon (C) content is 0.10% or more and 0.90% or less,
Chromium (Cr) content is 3.0% or more and 8.0% or less,
Carburizing after carving alloy steel having a manganese (Mn) content of 0.10% to 2.0% and a silicon (Si) content of 0.10% to 1.0% into a predetermined shape Or obtained by carbonitriding treatment and quenching and tempering, and the raceway surface of the race ring (inner ring and / or outer ring) and / or the rolling surface of the rolling element (these raceway surfaces and / or rolling surfaces are referred to as “raceway surface” Etc.)) and the total content of carbon and nitrogen ([C + N]) is 1.20 mass% or more and 2.50 mass% or less, and the amount of residual austenite on the raceway surface and / or the rolling surface (residual surface). γ) is 15% by volume or more and 40% by volume or less, and the surface hardness of the raceway surface and / or the rolling surface is 59 to 64 in Rockwell C hardness (HRC). To do.

The values of [C + N], residual γ, and surface hardness of the raceway surface and the like are values on the raceway surface and rolling surface in a completed state after grinding and finishing. As a form of the rolling bearing of the present invention, a ball is used as the rolling element, and the radius of curvature of the raceway grooves of the inner ring and the outer ring is 50.1% or more of the diameter of the ball.
The content is preferably 1.9% or less (preferably 51.0% or more and 51.9% or less).

According to the rolling bearing of the present invention, at least one of the inner ring, the outer ring, and the rolling element is formed of the above-mentioned specific alloy steel, and the raceway surface and the like [C + N].
By setting the residual γ and the surface hardness as described above,
Lubricated with traction oil, the radius of curvature (R) of the raceway grooves of the inner and outer rings is 5 (D) of the ball (rolling element).
Even if 0.1% or more and 51.9% or less, conventional alloy steel (bearing steel such as SUJ2, SCR420 or SCM42)
The bearing life can be made longer than that of a rolling bearing made of case hardening steel such as 0).

The critical significance of limiting the numerical values of each component of the alloy steel is as follows. [Carbon (C) content rate: 0.10% or more and 0.90% or less]
C is an element that forms a solid solution in the matrix to give hardness to the steel, and at the same time combines with elements such as Cr, Mo, V and W to form carbides to give wear resistance. In order to secure the hardness and wear resistance required for a rolling bearing after heat treatment, it is necessary to contain 0.10% or more.

If the content exceeds 0.90%, coarse eutectic carbides are likely to be formed during steelmaking, and rolling fatigue life and mechanical strength may be significantly reduced. Further, the cold workability and the turning workability become low, and the processing cost becomes high. The C content is preferably 0.55% or more and 0.80% or less. [Chromium (Cr) content: 3.0% or more and 8.0% or less]
Cr forms a solid solution in the matrix to improve hardenability, temper softening resistance, corrosion resistance, and the like, and forms fine carbides to prevent coarsening of crystal grains during heat treatment to prolong rolling fatigue life. And an element that increases wear resistance and heat resistance. It is also an element that stabilizes the structure to improve the dimensional stability and significantly suppresses the life reduction due to hydrogen invasion. If the Cr content is less than 3.0%, these effects cannot be sufficiently obtained.

If the Cr content is high, coarse eutectic carbides are likely to be formed during steelmaking, and rolling fatigue life and mechanical strength may be significantly reduced. Further, the cold workability and the turning workability become low, and the processing cost becomes high. In particular, if the Cr content exceeds 8.0%, carburizing and carbonitriding becomes difficult. Cr content is 4.0%
It is preferably at least 7.0%. [Manganese (Mn) Content: 0.10% to 2.0%] Mn is an element that acts as a deoxidizer during steelmaking. Further, like Cr, it has a function of forming a solid solution in the matrix to enhance the hardenability. Mn content is 0.10
If it is less than%, these effects cannot be substantially obtained.

When the Mn content exceeds 2.0%, not only cold workability and turning workability are lowered, but also the martensite transformation start temperature is lowered and sufficient hardness cannot be obtained. There is. The preferable range of the Mn content is 0.
It is 10% or more and 1.5% or less. [Silicon (Si) content of alloy steel: 0.10% or more and 1.0
% Or less] Si, like Mn, is an element that acts as a deoxidizer during steelmaking. Also, like Cr and Mn, it has a function of forming a solid solution in the matrix to enhance the hardenability.
It is also an effective element for strengthening the martensite of the matrix and extending the life of the bearing. Further, it also has the effect of increasing temper softening resistance, dimensional stability, and heat resistance. If the Si content is less than 0.10%, these effects cannot be substantially obtained.

If the Si content exceeds 1.0%, cold workability, turning workability, and forgeability may deteriorate. S
The preferable range of the content rate of i is 0.10% or more and 0.50.
% Or less. [Other Alloy Components of Alloy Steel, Inevitable Impurities] Oxygen (O) contained in the alloy steel forms oxide-based inclusions that cause a reduction in bearing life. Titanium (Ti) contained in the alloy steel forms titanium-based inclusions that cause a reduction in bearing life. Therefore, the O content is 10p
It is preferable that the pm or less and the Ti content be 20 ppm or less. [C + N] of raceway surface: 1.20 mass% or more 2.50
Mass% or less] [C + N] of the raceway surface, that is, the total content of carbon and nitrogen in the raceway surface of the raceway ring (inner ring and / or outer ring) and / or the rolling surface of the rolling element is 1.20 mass%. If it is less than 100%, it becomes difficult to reduce surface fatigue while ensuring sufficient rolling life and heat resistance. If it exceeds 2.50% by mass, carbides on the grain boundaries will be 10
In some cases, the rolling life may be shortened by coarsening to a size of μm or more or growing in a net shape.

Since the coarsening of the carbide can be reduced by substituting a part of carbon with nitrogen, it is preferable that the content of nitrogen in the raceway surface is 0.10% by mass or more. However, if the nitrogen content exceeds 0.30% by mass, grindability and the like are significantly reduced, leading to an increase in cost. That is, the content of nitrogen in the raceway surface is 0.10 mass% or more and 0.30 mass% or more.
The following is preferable. [Amount of retained austenite on the raceway surface: 15 vol% or more 4
0 volume% or less] Retained austenite has an effect of remarkably reducing surface fatigue, but in the case of a rolling bearing that supports the rotary shaft of a pulley of a belt type continuously variable transmission, the amount of retained austenite is less than 15 volume%. And this effect is not fully obtained. The amount of retained austenite on the raceway surface or the like is preferably 20% by volume or more.

When the amount of retained austenite on the raceway surface exceeds 40% by volume, the surface hardness may be lowered, or the race may be deformed when assembled. The amount of retained austenite on the raceway surface or the like is preferably 35% by volume or less. [Surface hardness of raceway surface: HRC 59 or more and 64 or less] If the surface hardness of the raceway surface (raceway surface and / or rolling surface) is less than 59 in Rockwell C hardness (HRC), wear resistance and surface I cannot reduce fatigue enough. The surface hardness of the raceway surface or the like is preferably HRC61 or more. The upper limit was set to 64 in consideration of toughness.

According to the present invention, at least one of the inner ring, the outer ring, and the rolling element is made of the above-mentioned specific alloy steel, and the above-mentioned specific alloy steel is formed into a predetermined shape and then carburized or carbonitrided. The total content of carbon and nitrogen on the raceway surface of the bearing ring and / or the rolling surface of the rolling elements is 1.20 mass% or more and 2.50 mass% or less, which is obtained by quenching and tempering. And / or the amount of residual austenite on the rolling surface is 15% by volume or more and 40% by volume or less, and the surface hardness of the raceway surface and / or the rolling surface is 59 or more and 64 or less in Rockwell C hardness (HRC), It has balls as rolling elements, the radius of curvature of the raceway groove of the inner ring and the outer ring is 50.1% or more and 51.9% or less of the diameter of the balls, and the rotation axis of the pulley around which the belt of the belt type continuously variable transmission is wound is To support Providing a rolling bearing used (radial ball bearing) with Applications.

According to this radial ball bearing, the ratio (R /
Since D) is reduced to the same range as in Japanese Patent Publication No. 8-30526 and the ball bearing is not easily displaced in the axial direction by the thrust load, misalignment between the pulleys is less likely to occur.
Further, since the above-mentioned specific alloy steel is used and the [C + N] of the raceway surface, the residual γ and the surface hardness are configured as described above, even if the conventional alloy steel (bearing steel such as SUJ2) is lubricated with traction oil. , SCR420 and SCM
Bearing life is longer than when using case hardening steel such as 420).

That is, in this radial ball bearing, the ratio (R / D) is reduced to reduce the misalignment between the two pulleys, the specific alloy steel described above is used, and [C + N] such as the raceway surface remains. The bearing life is lengthened by making γ and the surface hardness as described above. As a result, in the radial ball bearing that supports the pulley shaft of the belt type continuously variable transmission, it is possible to extend the bearing life while reducing the misalignment between the pulleys around which the belt is wound.

The present invention also provides a belt type continuously variable transmission in which the rotating shaft of the pulley around which the belt is wound is supported by the rolling bearing of the present invention.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

[0028]

[Table 1]

First, alloy steels A-1 to A-9 and B-1 to B5 having alloy compositions shown in Table 1 were prepared. Table 1 also shows the Cr equivalent of each alloy steel. Table 1
In the above, those whose alloy component contents are out of the range of the present invention are underlined. Using these alloy steels, radial ball bearings with a nominal number of 6208 (inner diameter 40 mm, outer diameter 80
mm, width 18 mm) to produce an inner ring and an outer ring. At that time, the radius of curvature Ri of the raceway groove 10 of the inner ring 1 shown in FIG.
The radius of curvature Re of the raceway groove 21 of the outer ring 2 was formed to various values.

After forming each alloy steel into a predetermined shape,
As the heat treatment, (A) carburizing or carbonitriding treatment and quenching and tempering, or (B) quenching and tempering only (soaking) were performed. In (A), after heating to 930 to 960 ° C. and carburizing or carbonitriding treatment for 1 to 3 hours,
After soaking for 1 hour, oil quenching was performed as it was. Tempering was performed at 160 ° C. In (B), 840 to 1050
Quenching at 160 ° C. and tempering at 160 ° C. were performed.

After the heat treatment, grinding finishing processing and super finishing processing were performed. The surface roughness of the raceway grooves 10 and 21 is 0.01 to
It was set within the range of 0.04 μmRa. Also, a ball 3 having a diameter (D) of 11.906 mm and made of SUJ2 and having a grade of 20 was prepared. This ball 3 is carbonitrided. A test bearing was assembled using the balls 3, the inner ring 1 and the outer ring 2 described above, and a metal corrugated press cage (the cage is omitted in FIG. 1).

Inner ring 1 and outer ring 2 for each test bearing
"Material", C concentration on raceway surface (carbon content), N concentration on raceway surface (nitrogen content rate), [C + N] (total content of carbon and nitrogen) on raceway surface, "Surface hardness of raceway surface""," Remaining γ of the raceway surface (retained austenite amount) "and" curvature radius of raceway groove (R) / diameter of ball (D) "have various configurations shown in Table 2. The radial internal clearance was set to be "C3 clearance" or less.

Ten test bearings were prepared for each and mounted on a ball bearing life tester manufactured by Nippon Seiko Co., Ltd., and a life test was conducted by rotating them under the following conditions. Vibration was measured during rotation, and the rotation was terminated when the vibration value of the bearing became 5 times the initial vibration value, and the rotation time up to this point was defined as the life. In addition, it was investigated which of the raceway surfaces of the inner and outer races had peeling at this point. When the vibration value of the bearing was not 5 times the initial vibration value, the test termination time was 3 times the calculated life under these conditions.

Next, the results of 10 test bearings of each type were plotted on a graph of the Weibull distribution (cumulative damage probability-life), and from this graph, peeling occurred in 10% of the bearings from the short life side. The total rotation time (L10 life) was calculated. Regarding the measured L10 life of each test bearing, a relative value was calculated with the calculated life set to "1". <Life test conditions> Rotational speed: 3900 rpm Radial load: 4800 N Axial load: 2000 N, 2 Hz oscillating lubricating oil: Showa Shell's continuously variable transmission lubricating oil "NS-1" classified as "traction oil" 2 tap water
Volume% mixture Oil temperature: 130 ° C. Rotating wheel: Inner ring The results are also shown in Table 2 below.

[0035]

[Table 2]

The relationship between the Cr content in the alloy steel used for the inner and outer rings of each test bearing and the obtained life ratio (relative value of L10 life) is shown in a graph in FIG. Further, the relationship between the total content ratio of C and N on the raceways of the inner ring and the outer ring of each test bearing and the obtained life ratio (relative value of L10 life) is shown in a graph in FIG. The range H1 in FIG.
Is the range of the Cr content of the alloy steel specified in the present invention (3.
0 to 8.0 mass%), and the range H2 in FIG. 3 is the range (1.2) of the total content of C and N on the raceway surface defined by the present invention.
0 to 2.50 mass%).

Further, when the bearing was kept at 130 ° C. for 1000 hours or more, and the outer diameter of the bearing was measured before and after that to measure the amount of dimensional change, in the test bearings No. 1 to 18 corresponding to the examples of the present invention, The dimensional change was so small that it could be ignored. As can be seen from these results, the test bearings of Nos. 1 to 18 have alloy components within the range of the present invention while the (R / D) of the inner ring and the outer ring is 50.1% or more and 51.9% or less. Using a certain alloy steel of A-1 to A-10 as a material, the total content of C and N on the raceway surface is in the range of 1.20 mass% or more and 2.50 mass% or less, and residual austenite on the raceway surface is used. The amount is in the range of 15% by volume or more and 40% by volume or less, and the surface hardness of the raceway surface is 59 or more and 6 in HRC.
Since it is in the range of 4 or less, the bearing life when lubricated with traction oil can be extended as compared with the test bearings of Nos. 19 to 29 which do not satisfy any one of the above items.

As described above, the inner ring and the outer ring have Nos. 1 to 18 satisfying the range of the present invention, so that both belts are wound as a radial ball bearing for supporting the pulley shaft of the belt type continuously variable transmission. Even if slippage occurs between the pulleys, surface fatigue does not easily occur even when slippage occurs, and a bearing having a long bearing life under traction oil lubrication can be obtained.

That is, according to the present invention, by using an alloy steel having a high chromium content and increasing the [C + N] of the raceway surface by carburizing or carbonitriding treatment, the structural stability and the surface fatigue resistance are improved. It was possible to extend the life of rolling bearings used in environments where slippage is likely to occur. Further, by setting the amount of retained austenite on the raceway surface within a predetermined range, heat resistance and dimensional stability are secured even when the amount of heat generated by slippage increases, and the seizure life is extended.

Particularly, the test bearings of Nos. 10 to 18 were carbonitrided, and the nitrogen concentration on the raceway surface was 0.1% by mass or more and 0.3% by mass or less.
The life ratio is higher than that of the test bearings of Nos. 10-19. The test bearings of Nos. 19 to 21 were obtained by smoldering using B-1 corresponding to the conventional bearing steel, and the "R / D" of the inner ring and the outer ring of each test bearing was obtained. Is changing. Here, the "R / D" of the inner ring is 50.1%
No. 20 and 53.0% No. 21 are 52.
The L10 life was shorter than that of No. 20, which was 0% (0.2 times the calculated life). From this result, it can be seen that when the conventional bearing steel is used, the bearing life is shortened when “R / D” is set to 50.1% or more and 51.9% or less.

[0041]

As described above, according to the present invention,
Specified alloy steel is used, and [C + N] such as raceway surface and residual γ
And surface hardness are reduced by heat generation and surface fatigue due to metal contact, and new surfaces are less likely to occur on the raceway surface, so they are lubricated with traction oil and the radius of curvature of the raceway grooves of the inner and outer rings is reduced. Even if (R) is 50.1% or more and 51.9% or less of the diameter (D) of the ball, conventional alloy steel (bearing steel such as SUJ2, SCR42
Bearing life can be made longer than that of a rolling bearing made of case hardening steel such as 0 or SCM420).

That is, the radius of curvature (R) of the raceway grooves of the inner ring and the outer ring is 50.1% or more of the diameter (D) of the ball and 51.9.
% Or less, a specific alloy steel is used, and [C + N] of the raceway surface, residual γ, and surface hardness are set to a specific configuration, thereby supporting the radial shaft that supports the pulley shaft of the belt-type continuously variable transmission. In the ball bearing, the bearing life can be extended while reducing the misalignment between the pulleys around which the belt is wound.

Further, according to the belt type continuously variable transmission of the present invention, the rolling shaft of the pulley around which the belt is wound is supported by the rolling bearing of the present invention, so that the center misalignment between both pulleys can be reduced and the length can be increased. Since the pulley can be stably rotated during the period, the durability of the belt can be maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a rolling bearing and a radius of curvature of raceway grooves of an inner ring and an outer ring.

FIG. 2 is a graph showing the relationship between the content ratio of chromium (Cr) in the alloy steel forming the material and the life ratio (relative value of L10 life) obtained from the results of the embodiment.

FIG. 3 is a graph showing the relationship between the total content of carbon (C) and nitrogen (N) in the raceways of the inner ring and the outer ring and the life ratio (relative value of L10 life) obtained from the results of the embodiment. Is.

FIG. 4 is a sectional view showing an example of a belt type continuously variable transmission of a vehicle.

5A and 5B are diagrams showing a separation form of a bearing ring, wherein FIG. 5A shows a case where the lubricating oil is mineral oil, and FIG. 5B shows a case where the lubricating oil is traction oil.

[Explanation of symbols]

1 inner ring 10 Inner ring raceway groove 11 Radial ball bearings (rolling bearings) 12 Radial ball bearings (rolling bearings) 2 outer ring 21 outer raceway groove 3 balls (rolling elements) 5 Input shaft (drive shaft) 6 Output shaft (driven shaft) 7 Input shaft pulley (primary pulley) 71 Fixed conical plate 72 Movable conical plate 8 Output shaft pulley (secondary pulley) 81 Fixed conical plate 82 Movable conical plate 9 belt 91 ring 92 Friction piece Diameter of D ball Ri radius of curvature of raceway groove of inner ring Re Radius of raceway raceway groove radius of curvature

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16C 19/06 F16C 19/06 33/66 33/66 Z F16H 9/12 F16H 9/12 B (72) Inventor Nobuaki Mitamura 1-5-50, Shinmei Kugenuma, Fujisawa-shi, Kanagawa F-Term (reference) at NSK Ltd. 3J050 AA03 BA03 BB03 CD10 DA01 3J101 AA02 AA42 AA52 AA62 BA53 BA54 BA55 BA70 CA40 DA02 DA03 EA02 FA31 FA41 GA01 GA11 4K AA22 BA03 BA04 CA06 CA07 DA01 DA02 DA06 DC02 DC03 DD02 DE02

Claims (4)

[Claims] 1. In a rolling bearing in which a plurality of rolling elements are rotatably arranged between an inner ring and an outer ring, at least one of the inner ring, the outer ring and the rolling elements is carbon (in mass ratio) C) content is 0.10% or more 0.9
0% or less, chromium (Cr) content of 3.0% or more 8.
Forming alloy steel with a content of manganese (Mn) of 0% or less, 0.10% or more and 2.0% or less, and a content of silicon (Si) of 0.10% or more and 1.0% or less into a predetermined shape After that, it is obtained by carburizing or carbonitriding treatment and quenching and tempering, and the total content of carbon and nitrogen in the raceway surface of the bearing ring and / or the rolling surface of the rolling element is 1.20 mass% or more and 2.50.
The amount of residual austenite on the raceway surface and / or the rolling surface is 15% by volume or more and 40 volume% or less, and the surface hardness of the raceway surface and / or the rolling surface is Rockwell C hardness (HRC). ) Is 59 or more and 64 or less. 2. A ball is used as a rolling element, and the radius of curvature of the raceway grooves of the inner ring and the outer ring is 50.1% or more of the diameter of the ball.
The rolling bearing according to claim 1, which is 9% or less. 3. A belt type continuously variable transmission used for supporting a rotary shaft of a pulley around which a belt is wound.
Rolling bearing described. 4. A belt type continuously variable transmission in which the rotating shaft of a pulley around which a belt is wound is supported by the rolling bearing according to claim 2.