JP2005121080A - Rolling bearing for supporting belt type continuously-variable transmission pulley shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing for a belt type continuously-variable transmission pulley shaft of long service life, capable of being properly used in the belt type continuously variable transmission by securing the hardness under high temperature environment, the stability in its dimension, the resistance to peeling fatigue and the resistance to white tissue separation, and selecting and strengthening a rolling element. <P>SOLUTION: In this rolling bearing for supporting the belt type continuously-variable transmission pulley shaft, at least one of an outer ring, an inner ring and the rolling element is composed of alloy steel including C of 0.6-1.2 mass%, Cr of 0.8-1.8 mass%, Si of 0.6-1.3 mass% and S of 0.018 mass% or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a belt-type continuously variable transmission pulley shaft supporting rolling bearing, and more particularly to extending the life of a rolling bearing that supports a primary pulley and a secondary pulley shaft.

  The belt-type continuously variable transmission 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. 1, pulleys 3 and 4 are respectively provided on an input shaft (drive shaft) 1 and an output shaft (driven shaft) 2 arranged in parallel, and a metal is provided between these pulleys 3 and 4. A belt 5 made of metal is wound around the belt. This belt 5 has a structure in which a large number of thin (about 2 mm thick) friction pieces 52 are attached to two rings 51 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 52 are pressed against each other.

  The driving force is transmitted from the input shaft pulley (primary pulley) 3 to the output shaft pulley (secondary pulley) 4 via the belt 5. Both pulleys 3 and 4 are composed of fixed conical plates 31 and 41 fixed to the respective shafts 1 and 2 and movable conical plates 32 and 42 movable in the axial direction by a hydraulic mechanism. Thus, a V-shaped pulley groove is formed.

  By moving the movable conical plates 32 and 42 of these pulleys 3 and 4 in the axial direction to change the groove width, and changing the position where the belt 5 contacts the pulleys 3 and 4 (effective rotation radius of the pulley), The gear ratio can be changed steplessly. For example, when the groove width of the input shaft pulley 3 is reduced, the effective rotation radius of the input shaft pulley 3 is increased, and thus a large gear ratio is obtained.

  Shaft portions (pulley shafts) 31 a and 41 a in which the fixed conical plates 31 and 41 of the pulleys 3 and 4 are integrated are supported by radial ball bearings 6 and 7. These pulley shafts 31a and 41a receive a thrust load as a reaction force when the shaft output is transmitted to the subsequent stage. Therefore, the radial ball bearings 6 and 7 are displaced in the axial direction by the thrust load, and the center in the groove width direction is shifted between the input shaft pulley 3 and the output shaft pulley 4 (so-called “center misalignment” occurs). There is a need to prevent. When the misalignment increases, the belt 5 may meander and damage may be caused by improper contact between the ring 51 and the friction piece 52, or the radial ball bearings 6 and 7 may slip and generate heat. Sometimes it grows.

  As a countermeasure, in the ball bearing that supports the pulley shaft, the ratio (R / D) of the curvature radius (R) of the raceway groove (R) of the inner ring and the outer ring to the ball diameter (D) is a normal standard design value (0.53). (50.1-50.9% for the inner ring and 50.1-51.9% for the outer ring) is known (see, for example, Patent Document 1). As the ratio (R / D) is smaller, the ball bearing is less likely to be displaced in the axial direction due to the thrust load.

  On the other hand, as a lubricating oil for a belt type continuously variable transmission, a lubricating oil for an automatic transmission having a high traction coefficient (in order to transmit power by smoothly operating a torque converter, a gear mechanism, a hydraulic mechanism, a wet clutch, etc.) Special oils such as ATF (Automatic Transmission Fluid) and continuously variable transmission fluid (CVTF) are used. In the case of rolling bearings used in these lubricating oils, the tangential force generated between the bearing ring and the rolling element increases, and the part away from the center of the contact ellipse where the normal contact surface pressure is the largest, that is, The PV value (product of contact surface pressure and speed) is the largest, so the lubricating film is destroyed and the frequency of metal contact increases, so that heat often occurs.

  Particularly, in recent years, a belt type continuously variable transmission applicable to a large engine exceeding 2.5L is eagerly desired. However, in the case of a bearing used in such a belt type continuously variable transmission, it is very high. It is estimated that torque is applied and heat generation is likely to occur.

  Further, in a dry belt type continuously variable transmission whose belt is made of resin, torque is transmitted by the belt in an oil-free environment. For this reason, in the case of a rolling bearing used in such a continuously variable transmission, since oil lubrication is difficult, grease lubrication is performed, but heat is more likely to occur than in oil lubrication.

  Such heat generation causes a decrease in bearing hardness and a decomposition of retained austenite. Therefore, a rolling bearing applied to a belt-type continuously variable transmission requires maintenance of hardness and dimensional stability under a high temperature environment. Further, in rolling bearings applied to belt type continuously variable transmissions, in addition to the above-described problems under high temperature environments, peeling fatigue due to use under severe lubrication conditions is also a problem.

  As a countermeasure, it is known to use a four-point contact ball bearing in which the total austenite amount of the inner ring and ball is 5% or less and the retained austenite amount of the raceway surface of the inner ring or outer ring is 10% or more ( For example, see Patent Document 2.) Here, by reducing the total austenite amount to 5% or less, the dimensional change due to decomposition of residual austenite during heat generation is reduced, and the surface austenite amount on the raceway surface is suppressed to 10% or more to suppress surface fatigue. doing.

On the other hand, the bearing usage environment in belt-type continuously variable transmissions is significantly different from that of conventional automatic transmissions (small amount of lubricating oil, high vibration, high load, high temperature, special additives contained in ATF and CVTF The influence of the above, etc.), which has not been a problem in the past, has become a problem, such as white tissue peeling and a decrease that peeling occurs preferentially in the rolling element rather than the inner and outer rings, which are usually the weakest parts.
Japanese Patent Publication No. 8-30526 (Fig. 1) JP-A-10-292859 (page 3, FIG. 1)

  However, since the technique described in Patent Document 1 has been made to increase the durability of the belt of the belt-type continuously variable transmission, there is no mention of the life of the rolling bearing that supports the rotating shaft of the pulley. .

  Moreover, since the technique described in Patent Document 2 does not have resistance to decomposition of retained austenite in a high temperature environment, wear or peeling fatigue caused by hardness reduction and dimensional stability deterioration at high temperatures, There is still room for improvement in terms of suppressing the fatigue characteristic of belt-type continuously variable transmissions.

  Furthermore, the techniques described in Patent Documents 1 and 2 have not improved problems peculiar to bearings used in belt-type continuously variable transmissions such as white tissue peeling and preferential peeling of rolling elements.

  The present invention has been made paying attention to the above-mentioned problems, ensuring hardness, dimensional stability, anti-peeling fatigue properties, and anti-white tissue peeling properties under high temperature environments, and selecting rolling elements. The purpose of the present invention is to provide a long-life belt-type continuously variable transmission pulley shaft-supporting rolling bearing that can be suitably used for a belt-type continuously variable transmission.

In order to achieve this object, the present invention has the following configuration.
(1) An outer ring having a rolling surface on the inner circumferential surface, an inner ring having a rolling surface on the outer circumferential surface, and a rolling surface disposed between the rolling surface of the outer ring and the rolling surface of the inner ring. In a belt-type continuously variable transmission pulley shaft support rolling bearing provided with a plurality of rolling elements,
At least one of the outer ring, the inner ring, and the rolling element has C of 0.6 to 1.2% by mass, Cr of 0.8 to 1.8% by mass, Si of 0.6 to 1.3% by mass, S A belt-type continuously variable transmission pulley shaft-supporting rolling bearing, characterized in that the alloy steel is 0.018% by mass or less.
(2) The alloy steel is characterized in that the amount of retained austenite on the rolling surface is 15% by volume or less, and the sum of the surface carbon concentration and the surface nitrogen concentration is 0.8 to 1.4% by mass (1) A rolling bearing for supporting a belt-type continuously variable transmission pulley shaft as described in 1.
(3) The belt-type continuously variable transmission pulley shaft supporting rolling bearing according to (1) or (2), wherein the alloy steel is subjected to carburizing or carbonitriding.
(4) The rolling bearing for supporting a belt-type continuously variable transmission pulley shaft according to any one of (1) to (3), wherein at least the rolling element is the alloy steel.
(5) The rolling bearing for supporting a belt-type continuously variable transmission pulley shaft according to any one of (1) to (4), further comprising sealing means for sealing the bearing space.

  According to the rolling bearing having the configuration of (1), since an appropriate amount of Si is contained, the structure can be stably maintained even at a high temperature, so that dimensional stability and hardness are not deteriorated. Moreover, since the penetration | invasion of hydrogen which causes white structure formation can be suppressed by reducing S, a rolling bearing becomes long life.

Further, according to the rolling bearing having the configuration (2), by adjusting the residual austenite amount, the surface carbon concentration, and the surface nitrogen concentration to appropriate amounts, it is possible to strengthen against surface fatigue, so that it has a longer life. Become. Here, the rolling surface includes at least one of rolling surfaces of the outer ring and the inner ring and a rolling surface of the rolling element.
Furthermore, according to the rolling bearing having the configuration of (3), a compressive residual stress can be applied to the rolling surface, and it can be made strong against surface fatigue, so that it has a long life.

Further, according to the rolling bearing having the configuration of (4), by selecting and strengthening the rolling element, it is possible to prevent the rolling element peeling, which is a problem peculiar to the rolling bearing for supporting the belt type continuously variable transmission pulley shaft. Long service life.
Furthermore, according to the rolling bearing having the configuration of (5), since contamination can be remarkably reduced by the seal, the life is further prolonged.

  Hereinafter, the action of the alloy component used in the present invention, the reason for limiting the component range, and other critical significance will be described.

[C: 0.6 to 1.2% by mass]
C is an element necessary for improving the hardness after quenching and tempering. When carbonitriding, the surface carbon concentration increases. For this reason, this value is the C content in the raw material stage.
If the C content exceeds 1.2% by mass, enormous carbides are generated at the raw material stage, so that machinability and toughness are deteriorated. Therefore, the upper limit of the C content is set to 1.2% by mass.
On the other hand, if the content is less than 0.6% by mass, sufficient hardness cannot be obtained as it is. In the case of carbonitriding, when using it as a bearing, it is necessary to lengthen the carburizing and carbonitriding treatment time in order to obtain a carbon concentration that can obtain the required hardness up to the depth at which shear stress acts by the load, The heat treatment productivity is lowered and the cost is disadvantageous. Therefore, the lower limit of the C content is set to 0.6% by mass.

[Cr: 0.8 to 1.8% by mass]
Cr is an element effective for improving hardenability and temper softening resistance. Further, by precipitation hardening that uniformly forms fine carbides, sufficient surface hardness can be obtained even if high temperature tempering is performed, and the toughness of the base can be improved. And it has a function which improves abrasion resistance with hard and fine Cr carbide. Furthermore, since Cr is a carbide forming element, as a result of increasing the C concentration of the carbonitriding layer, the carbonitriding property of the material can be enhanced even if a large amount of Si having carburization inhibition is contained.
In order to exhibit these actions and effects and ensure the required surface hardness of HRC 60 or more, the lower limit of the Cr content was set to 0.8 mass%.
On the other hand, if the content exceeds 1.8% by mass, a huge carbide is generated at the raw material stage, and there is a problem that the bearing life is reduced due to stress concentration around the carbide. Further, an increase in Cr content more than necessary is disadvantageous in terms of cost, and when trying to refine giant carbides, quenching at high temperatures is required, and heat treatment productivity is reduced. Therefore, in the present invention, the upper limit value is set to 1.8% by mass.

[Si: 0.6 to 1.3% by mass]
Si is an element effective in delaying the decomposition of retained austenite at a high temperature to stabilize the structure and improving the temper softening resistance. In order to sufficiently obtain the effect, the lower limit of the Si content was set to 0.6% by mass. However, since the increase in the content leads to a decrease in mechanical strength, a machinability, and a carbonitridability, the upper limit of the Si content is set to 1.3% by mass.

[S: 0.018 mass% or less, preferably 0.008 mass% or less]
S is an impurity in steel and is usually present in steel as an A-based inclusion such as MnS.
A-based inclusions act as a chip breaker, have the effect of improving the machinability of steel, and are often used effectively. From the viewpoint of life, B-type inclusions and D-type inclusions are used. However, since it has been considered that the bearing life is not greatly affected, it has not been considered sufficiently important to reduce S as much as possible.
However, like a rolling bearing for a belt type continuously variable transmission pulley support shaft, the bearing is used in a special lubricating oil in a usage environment in which specific conditions such as high temperature, high vibration, high speed, and high load are satisfied. In some cases, hydrogen generated by decomposition of moisture and base oil in the lubricating oil in the contact surface penetrates into the steel due to interaction with MnS in the steel, resulting in a significant decrease in service life. There is. This is due to the intrusion of hydrogen that accumulates in a high strain field, thereby reducing the yield strength of the steel and causing a structural change called a white structure with local plastic flow.
The inventors of the present application have clarified that the life can be improved by setting S to 0.018% or less with respect to the early peeling due to the above specific tissue change. Therefore, the upper limit of S is set to 0.018%. The upper limit is preferably 0.008%.

[The sum of the carbon concentration and the nitrogen concentration in the surface layer portion forming the rolling surface is 0.8 to 1.4% by mass]
In order to obtain sufficient rolling fatigue strength as a bearing, the sum of the surface carbon concentration and the surface nitrogen concentration needs to be 0.8% by mass or more. In addition, when the sum of the surface carbon concentration and the surface nitrogen concentration exceeds 1.4% by mass, it becomes easy to form giant charcoal / nitride, and such giant charcoal / nitride becomes a defect, rolling fatigue life. May fall, the upper limit was made 1.4 mass%.

[The amount of retained austenite in the surface layer portion forming the rolling surface is 3 to 15% by volume]
Residual austenite is effective in suppressing surface fatigue such as indentation origin peeling and peeling fatigue in an environment where wear powder or the like is mixed in the bearing. In order to sufficiently exhibit this effect, the lower limit is set to 3% by volume in the present invention.
On the other hand, the retained austenite transforms into martensite in a high temperature environment, and at this time, a dimensional change occurs, and the clearance between the inner and outer rings of the bearing is reduced, which is a factor that accelerates peeling fatigue. For this reason, it is preferable to make the amount of residual austenite 15 volume% or less in the rolling surface which is a part with the highest residual austenite by tempering. The tempering temperature at this time is preferably about 200 to 400 ° C. in order to make the retained austenite 15 volume% or less.

[Significance of carburizing or carbonitriding]
Conventionally, it has been known that peeling resistance is improved by generating compressive residual stress in the vicinity of the surface (for example, JP-A-5-288257). In the present invention, medium or high carbon steel is subjected to carburizing or carbonitriding treatment to give a carbon concentration gradient in the vicinity of the surface, thereby imparting compressive residual stress to the surface and improving peelability.

  Moreover, in this invention, it can selectively add in the range of the quantity which described the following element together as needed.

[Mn: 0.2 to 2.0% by mass]
Mn acts as a deoxidizing and desulfurizing agent at the time of steelmaking, and plays a major role in improving hardenability, so at least 0.2% by mass is necessary. For this reason, the minimum of Mn content was made into 0.2 mass%.
However, if the content is more than 2.0% by mass, a lot of nonmetallic inclusions are produced, so that the life is reduced, and in addition, machinability such as forgeability and machinability is lowered. Therefore, the upper limit of the Mn content is set to 2.0% by mass.

[O: 10 ppm or less]
Since O is an oxide-based nonmetallic inclusion (in particular, Al ₂ O ₃ ) generating element, it has an effect of reducing the life, so that its content needs to be reduced as much as possible. Therefore, the upper limit of the O content is preferably 10 ppm.
In addition, since Al produces oxide-based nonmetallic inclusions such as Al ₂ O _3, it is detrimental to the service life in the same way as O. However, since Al itself has an effect of preventing coarsening of crystal grains, it is effective to contain 100 to 400 ppm or less.

[P: 0.02 mass% or less]
P is an element that reduces rolling life and toughness. For this reason, the P content is preferably as small as possible. In this respect, the P content is preferably suppressed to 0.02% by mass or less.

[Ni: 2.0% by mass or less]
Ni is a strong austenite-stabilizing element, has the effect of suppressing the formation of δ ferrite, further improving the toughness by solid solution in the matrix and enhancing the high temperature characteristics. However, if it is added more than necessary, a large amount of retained austenite is generated and sufficient quenching hardness cannot be obtained. Considering these points, the upper limit is made 2.0 mass% or less.

[Cu: 0.05 to 2.0% by mass]
Cu is an element having a slight austenite stabilizing effect similar to Ni, and has the effect of suppressing the formation of δ ferrite and improving the corrosion resistance and acid resistance, so it should be added selectively to the steel of the present invention. Can do. The lower limit at that time is 0.05% by mass or more, preferably 0.5% by mass or more. Moreover, since a hot crack may be produced in the hot forging process of the bearing manufacturing process if added in a large amount, the upper limit is set to 2.0% by mass.

[Other inevitable impurities]
As elements other than the above alloy elements and Fe, inevitable impurities such as Ti and Nb are each included in an amount of 100 ppm or less.

[Seal member that seals bearing space]
Since the belt-type continuously variable transmission is a device incorporating a gear mechanism and a clutch mechanism, there is a concern that the wear metal powder from these devices may be mixed into the bearing. Therefore, it is preferable to provide a seal structure in order to further improve the reliability of the bearing life.

  According to the present invention, the belt type continuously variable transmission is ensured by ensuring hardness, dimensional stability, anti-peeling fatigue characteristics, and white tissue peeling resistance in high temperature environments, and by selecting and strengthening rolling elements. A long-life belt-type continuously variable transmission pulley shaft-supporting rolling bearing that can be suitably used in a machine can be provided.

  The present invention aims to improve the durability by devising the material characteristics of the rolling bearing for supporting a belt type continuously variable transmission pulley shaft. The structure illustrated in carrying out the present invention is the same as that of a conventionally known belt-type continuously variable transmission pulley shaft supporting rolling bearing including the structure shown in FIG. Therefore, description of the specific structure of the belt-type continuously variable transmission pulley shaft support rolling bearing is omitted.

Hereinafter, specific material characteristics of the rolling bearing of the present invention will be described using experimental results.
In the experiment, life evaluation under oil bath lubrication was performed using a deep groove ball bearing of JIS model number 6207. Here, the outer ring and the inner ring were molded into a predetermined shape with the material having the composition shown in Table 1, then heated to 840 to 1050 ° C., carburized or carbonitrided for 1 to 20 hours, and then oil-quenched. . Then, the tempering which heats at 200-400 degreeC for 1.5 to 2.0 hours was performed, and the polishing finishing process and the superfinishing process were performed. Table 2 shows the sum of the surface carbon concentration and the surface nitrogen concentration (mass%) and the amount of surface retained austenite (volume%) of each steel at the time when the finishing is performed.

  On the other hand, the material of the rolling element is the test bearing No. in Table 2. 1 and no. In No. 4, the same material as the inner and outer rings was used for comparison, and the other materials were carbonitrided to JIS steel type SUJ2. However, test bearing No. in Table 2 For No. 17, the indicated material was applied only to the rolling elements, and SUJ2 was applied to the inner and outer rings.

  Here, the “surface layer portion” indicates a portion from the surface to a depth of 20 μm. The surface carbon / nitrogen concentration and the amount of retained austenite on the surface were measured with an emission analyzer and an X analyzer, respectively.

  After assembling the test bearing using the inner ring, outer ring, and rolling element completed as described above, and a metal cage, the gap formed between the inner ring and the outer ring and containing the ball is sealed. Sealed with members. However, test bearing No. in Table 2 No. 19 does not have a seal member for comparison.

  The groove curvature of the outer ring and inner ring of the assembled bearing is 51% of the rolling element diameter, the radial internal clearance is C3 clearance or less, and the rolling element surface roughness of the inner ring and outer ring is about 0.01 to 0.04 μm. is there.

  The bearings were evaluated for life using the belt type continuously variable transmission unit shown in FIG. In this belt type continuously variable transmission unit, the input shaft 1 of the primary pulley 3 and the output shaft 2 of the secondary pulley 4 are supported by a pair of rolling bearings 6a, 6b, 7a, 7b, respectively. Of these four rolling bearings, each test bearing was attached as a primary front bearing (that is, a rolling bearing that supports the input shaft 1 on the engine side relative to the primary pulley 3) 6a. The other rolling bearings 6b, 7a, and 7b were the same in each test. In addition, the belt 5 of this belt type continuously variable transmission unit has 280 sheets of 2 mm thick, in a two-row ring 51 having a structure in which ten steel sheets having a thickness of 0.2 mm are stacked, as in FIG. The friction piece 52 is attached, and the belt length is 600 mm. The life test was conducted under the following conditions. In the evaluation, the vibration generated in the bearing during the rotation test was measured, and the bearing life was determined when the vibration value during rotation became twice the initial vibration value. The results are also shown in Table 2. The life in Table 2 is the test bearing no. The relative value when the lifetime of 26 is set to 1 is shown.

[Life test conditions]
Test bearing: 6207 deep groove ball bearing rotational speed: 1000-6500 min ⁻¹
P (load load) / C (dynamic load rating): max0.2
Lubricating oil: Commercially available CVT exclusive oil (Showa Shell, NS-1)
Oil temperature: 100-160 ° C

  As can be seen from the results in Table 2, no. Test bearings 1 to 19 have C of 0.6 to 1.2% by mass, Cr of 0.8 to 1.8% by mass, Si of 0.6 to 1.3%, and S of 0.018% or less. No. 2 which does not satisfy these requirements. Compared with 20 to 26 test bearings, it is possible to suppress deterioration in dimensional stability at high temperatures, decrease in hardness, and formation of a white structure, thereby extending the bearing life.

  Test bearing No. 1-19. Nos. 1 to 12 all have a longer life of 5 or more. 13 to 19 all had a lifetime of less than 5. From this result, S is 0.008% by mass or less, sufficiently strengthened against white structure-resistant peeling, and the amount of retained austenite on the rolling surface is 3 to 15% by volume, or the surface carbon concentration and When the sum of the surface nitrogen concentration is 0.8 to 1.4% by mass, it can be strengthened against surface fatigue, and it can be seen that a longer life bearing can be obtained.

  Here, the test bearing No. 5 and no. 18 shows that the alloy components, the heat treatment, and the quality such as the surface carbon / nitrogen concentration and the amount of retained austenite after the heat treatment are different from each other in test bearing No. 18. 2 and no. This is an example in which the long-life effect could not be sufficiently exhibited because no carbonitriding treatment was performed. From this result, it can be seen that the rolling bearing of the present invention has a longer life effect by performing carbonitriding.

  In addition, test bearing No. 1 and no. No. 4 shows that the alloy components, the heat treatment, and the quality such as the surface carbon / nitrogen concentration and the amount of retained austenite after the heat treatment are different in test bearing No. 4, respectively. 2 and no. This is an example in which it is confirmed that the life is further extended when the material characteristics of the present invention are applied not only to inner and outer rings but also to rolling elements. Test bearing No. No. 17 is an example in which the indicated material is applied only to rolling elements, and the inner and outer rings are confirmed to have a long life even when SUJ2 is applied. From this result, it can be seen that the rolling bearing of the present invention can have a long life when applied to at least a rolling element.

  Similarly, the test bearing no. No. 19 shows the test bearing No. 19 in terms of alloy components, heat treatment, and quality such as surface carbon / nitrogen concentration and retained austenite amount after heat treatment. This is an example in which the long-life effect could not be sufficiently exhibited because the seal member is not mounted, although it is the same as that of 16. From this result, it is understood that the rolling bearing of the present invention has a longer life by adopting the seal member.

As described above, according to the rolling bearing for supporting a belt-type continuously variable transmission pulley shaft of the present invention, at least the rolling element is formed of a specific alloy steel, and the carbon concentration of the surface layer portion forming the rolling surface is By limiting the sum of nitrogen concentration and the amount of retained austenite to a specific range, it is possible to improve the hardness, dimensional stability, peeling resistance and white structure-resistant peeling characteristics under high temperature environment, resulting in long life It can be.
In addition, the belt type continuously variable transmission to which the rolling bearing of the present invention is applied can stably rotate the pulley for a long period of time by supporting the rotating shaft of the pulley with a long-life rolling bearing. Can be held for a long time.

1 is a schematic cross-sectional view of a belt type continuously variable transmission that is an object of the present invention. It is the schematic of the belt-type continuously variable transmission unit used for the experiment of this embodiment.

Explanation of symbols

1 Input shaft 2 Output shaft 3 Primary pulley 4 Secondary pulley 5 Belts 6, 7, 6a, 6b, 7a, 7b Radial ball bearings (rolling bearings)

Claims (5)

An outer ring having a rolling surface on the inner circumferential surface, an inner ring having a rolling surface on the outer circumferential surface, and a plurality of rolling wheels disposed between the rolling surface of the outer ring and the rolling surface of the inner ring. In a belt-type continuously variable transmission pulley shaft support rolling bearing provided with a moving body,
At least one of the outer ring, the inner ring, and the rolling element has C of 0.6 to 1.2% by mass, Cr of 0.8 to 1.8% by mass, Si of 0.6 to 1.3% by mass, S A belt-type continuously variable transmission pulley shaft-supporting rolling bearing, characterized in that the alloy steel is 0.018% by mass or less.   2. The alloy steel according to claim 1, wherein the amount of retained austenite on the rolling surface is 15% by volume or less, and the sum of the surface carbon concentration and the surface nitrogen concentration is 0.8 to 1.4% by mass. Rolling bearing for belt type continuously variable transmission pulley shaft support.   The rolling bearing for supporting a belt-type continuously variable transmission pulley shaft according to claim 1 or 2, wherein the alloy steel is subjected to carburizing or carbonitriding.   The rolling bearing for supporting a belt-type continuously variable transmission pulley shaft according to any one of claims 1 to 3, wherein at least the rolling element is the alloy steel.   The rolling bearing for supporting a belt type continuously variable transmission pulley shaft according to any one of claims 1 to 4, further comprising sealing means for sealing the bearing space.

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