JP2014013058A - Needle-shaped roller bearing retainer and needle-shaped roller bearing - Google Patents

Abstract

An object of the present invention is to provide a needle roller bearing retainer that can suppress wear even in a high speed and high load environment and can rotate smoothly without causing seizure, and a needle roller bearing that exhibits excellent durability in a high speed and high load environment. provide.
A needle roller bearing retainer that rotatably supports a planetary gear of a planetary gear mechanism, comprising: an annular portion; and a plurality of column portions extending in an axial direction from the annular portion, A needle roller bearing retainer having a roller between the adjacent column portions and having a lubricating layer made of iron sulfide on the outer peripheral surface as well as being used in the outer ring guide, and the outer ring guide. Needle roller bearing that is a type.
[Selection] Figure 5

Description

  The present invention relates to a needle roller bearing that rotatably supports a planetary gear of a planetary gear mechanism, and a cage incorporated in the needle roller bearing.

  In an automatic transmission mounted on a vehicle or the like, a planetary gear mechanism is generally used. Here, since the needle roller bearing uses a small diameter roller, it can be accommodated in a space where the difference between the inner ring outer diameter and the outer ring inner diameter is small, so that the planetary gear of the planetary gear mechanism can be rotated freely. It is preferable to use it for supporting because it contributes to the compactness of the automatic transmission on which it is mounted.

  By the way, in recent years, there is a tendency to increase the number of stages in an automatic transmission for the purpose of improving fuel consumption. However, if the automatic transmission, which is currently in the 4th speed, is to be multistaged, for example, to the 5th or 6th speed, the rotation speed and revolution speed of the planetary gear of the planetary gear mechanism that transmits power increases. is there. Along with such changes in specifications, needle roller bearings with cages have been developed that have lower friction and better lubricity than conventional needle roller bearings called so-called full rollers that do not use cages. .

  Here, in the planetary gear mechanism, the planetary gear revolves around the sun gear while rotating, but at this time the needle roller bearing supporting the planetary gear also rotates and revolves around the sun gear. In particular, centrifugal force due to revolution is applied to the needle roller bearing. Therefore, when the needle roller bearing is provided with a cage, the cage is pressed against the outer ring (inner peripheral surface of the planetary gear) by centrifugal force based on revolution, so that the sliding between the outer ring and the cage is performed. Movement will occur. Such sliding increases the drag resistance of the needle roller bearing, and may cause premature wear and abnormal heat generation, as well as deformation and seizure of the cage.

  Therefore, in Patent Document 1, local wear due to contact between the guide surface of the pocket of the cage and the roller is suppressed by forming an electroless nickel coating in which a fluororesin is dispersed on the cage. However, since the coating film contains fluorine, the hardness is small, and since the fluororesin easily repels oil, the ability to retain lubricating oil is not high. For this reason, it is worn out in the current situation where further speedup is required.

JP 2004-340270 A

  The present invention has been made in view of the above-mentioned problems, and provides a needle roller bearing retainer that can be smoothly rotated without causing seizure even in a high-speed and high-load environment. Objective. Another object of the present invention is to provide a needle roller bearing that exhibits excellent durability even in a high-speed and high-load environment.

In order to achieve the above object, the present invention provides the following needle roller bearing cage and needle roller bearing.
(1) A needle roller bearing retainer that rotatably supports a planetary gear of a planetary gear mechanism,
It has an annular part and a plurality of pillars extending in the axial direction from the annular part, holds a roller between the neighboring pillars, and is used in an outer ring guide, and has an outer peripheral surface made of iron sulfide. A needle roller bearing retainer comprising a lubricating layer.
(2) The needle roller bearing retainer as described in (1) above, wherein the lubricating layer is formed by electrolytic treatment.
(3) A needle roller bearing that rotatably supports the planetary gear of the planetary gear mechanism,
A needle roller bearing comprising the cage according to the above (1) or (2) and being an outer ring guide type.
(4) The needle roller bearing according to (3), wherein the needle roller bearing is lubricated with a lubricating oil containing an oily agent.

  The cage for a needle roller bearing according to the present invention has an excellent anti-wear effect due to the lubricating layer made of iron sulfide, and hardly causes seizure in a high-speed and high-load environment. Further, since the lubricating layer is soft, the counterpart material (outer ring raceway surface) is not damaged. Furthermore, even if the lubricating layer is worn, irregularities remain and function as an oil sump, the lubricating oil retention capability is high, and the lubricating life is extended. Therefore, the needle roller bearing of the present invention also exhibits excellent durability even in a high speed and high load environment.

It is sectional drawing which shows an example of the automatic transmission of the vehicle containing a needle roller bearing. It is an exploded view of a planetary gear mechanism. It is a figure which shows the operating principle of a planetary gear mechanism. It is a figure shown in the state which incorporated the needle roller bearing in the planetary gear mechanism. It is a perspective view which shows an example of the retainer for needle roller bearings. It is a schematic diagram which shows a carrier revolution tester. It is the figure which measured the holder outer diameter surface of the comparative example 1 after an abrasion test with the non-contact-type shape measuring device. It is the figure which measured the holder outer diameter surface of the comparative example 2 after an abrasion test with the non-contact-type shape measuring device. It is the figure which measured the holder outer diameter surface of Example 1 after an abrasion test with the non-contact type shape measuring device.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of an automatic transmission for a vehicle including a needle roller bearing. In the automatic transmission 1 shown in the figure, the torque output from the crankshaft 2 of the engine is transmitted through the torque converter 3 and is further transmitted through a plurality of stages through planetary gear mechanisms 4, 5, 6, etc. combined in a plurality of rows. And then output to a wheel (not shown) via the differential gear 7 and the drive shaft 8.

  FIG. 2 is an exploded view of the planetary gear mechanism 4 (5 and 6 are basically the same). In FIG. 2, the planetary gear mechanism 4 includes a ring gear 4a having internal teeth, a sun gear 4b having external teeth, three planetary gears 4c meshing with the ring gear 4a and the sun gear 4b, and three pinion shafts 4e. The gear 4c is rotatably supported, and has a carrier 4d that can also rotate.

  The operating principle of the planetary gear mechanism 4 is shown in FIG. First, in the case of the first speed, as shown in FIG. 2A, a large reduction ratio can be obtained by setting the sun gear 4b on the drive side, the planetary gear 4c (carrier) on the driven side, and fixing the ring gear 4a. . Next, in the case of the second speed, as shown in FIG. 3 (b), the sun gear 4b is fixed, the planetary gear 4c (carrier) is set to the driven side, and the ring gear 4a is set to the drive side. A ratio is obtained. Further, in the case of the third speed, as shown in FIG. 3 (c), the sun gear 4b is fixed, the planetary gear 4c (carrier) is set to the drive side, and the ring gear 4a is set to the driven side, thereby obtaining a small reduction ratio. It is done. In the case of reverse, as shown in FIG. 3 (d), the sun gear 4b is driven, the planetary gear 4c (carrier) is fixed, and the ring gear 4a is driven, so that output is output with respect to the input. Can be reversed. In addition, the above shows an example of the operation of the planetary gear mechanism 4, and the operation is not necessarily limited to this operation.

  FIG. 4 is a view showing the needle roller bearing incorporated in the planetary gear mechanism. As shown in FIG. 4, the needle roller bearing 10 is disposed between a pinion shaft (inner ring) 4e and a planetary gear (outer ring) 4c, and rotatably supports the planetary gear 4c. The needle roller bearing 10 includes a plurality of rollers 11 and a needle roller bearing retainer (hereinafter simply referred to as “retainer”) 12 that holds them. In the pinion shaft 4e, an oil passage 4f extending along the axis from the right side in FIG. 4 and extending to the outer peripheral surface at the center is formed, and lubricating oil is supplied. The cage 12 is used for outer ring guidance. A washer 4g is disposed between the carrier 4d and the planetary gear 4c.

  FIG. 5 is a perspective view of the cage 12. As shown in the figure, the cage 12 has a configuration in which a pair of annular portions 12a are connected by a plurality of column portions 12b. A space for holding the rollers 11 is formed between the adjacent column portions 12b. Each column portion 12b has a reduced diameter portion 12c that is reduced in diameter in the center in the axial direction (that is, close to the axial line of the cage 12), and expands from both sides in the axial direction of the reduced diameter portion 12c to the annular portion 12a. The outer peripheral surface (indicated by double hatching in the figure) is an outer diameter guide surface (that is, a surface in sliding contact with the outer ring) 12d. The cage 12 having such a shape is called an M-type cage. Moreover, the holder | retainer 12 is formed by punching one steel plate, forming a pillar part, and then rolling and welding both ends.

  In the present invention, a lubricating layer made of iron sulfide is formed on the cage 12. In order to form the lubricating layer, for example, electrolysis is performed in a molten salt (NaSCN + KSCN) bath at 190 ° C. using the cage 12 as an anode and the bathtub as a cathode. The iron source is supplied from a steel material forming the cage 12. By this electrolytic treatment, iron sulfide diffuses on the surface of the cage 12 to form a layer. Iron sulfide is soft and does not wear itself and damage the mating material. Further, the surface of the cage 12 is eluted and roughened during the electrolytic treatment, and fine irregularities remain when the lubricating layer is worn, and functions as a reservoir of lubricating oil for lubrication.

  In addition, as for the surface roughness of the holder | retainer 12 after forming a lubricating layer, 0.5-2.0 micrometers is preferable by calculated average roughness Ra. Moreover, it is preferable that Vickers hardness is Hv200 or less. By setting it as such surface roughness and Vickers hardness, the recessed part which has an oil sump effect can be formed, without wearing an other party material. When the calculated average roughness Ra is less than 0.5, it is difficult to form a recess that can sufficiently obtain an oil retention effect, and when the calculated average roughness Ra is more than 2.0 or the Vickers hardness is more than Hv200, abrasive wear occurs. The other material is easily damaged.

  Moreover, although there is no restriction | limiting in the thickness of a lubricating layer, 1-10 micrometers is preferable. Such surface roughness, hardness, and thickness can be adjusted by electrolytic treatment conditions.

  There is no limitation on the lubricating oil, and various automatic transmission oils (ATF) can be used. However, it is preferable to contain an oily agent because the adsorptivity to the lubricating layer is enhanced and the wear prevention effect is enhanced. Examples of oily agents include fatty acids such as oleic acid and stearic acid, fatty acid alcohols such as oleyl alcohol, fatty acid esters such as polyoxyethylene stearic acid ester and polyglyceryl oleic acid ester, phosphoric acid, tricresyl phosphate, lauric acid ester or poly Phosphoric acid esters such as oxyethylene oleyl ether phosphoric acid can be used.

  Moreover, you may add other additives, such as antioxidant and an antiwear agent, to lubricating oil as needed.

  Examples The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereby.

Example 1
The steel material was processed to produce a needle roller bearing cage as shown in FIG. Then, in a 190 ° C. molten salt (NaSCN + KSCN) bath, a cage was used as an anode, and a bathtub was used as a cathode to form a lubrication layer made of iron sulfide, whereby Test Holder A was obtained.

(Comparative Example 1)
A cage having the same shape as that of Example 1 was prepared, a phosphate chemical conversion treatment was performed to form a manganese phosphate coating, and test cage B was obtained.

(Comparative Example 2)
A cage having the same shape as that of Example 1 was produced, and a nickel-phosphorus film was formed by electroless plating to obtain a test cage C.

(Abrasion test)
The test cages A to C produced above were incorporated into needle roller bearings to form test bearings, and the test bearings were mounted on a carrier revolution tester shown in FIG. 6 and operated under the following conditions. After the test, the outer diameter surface of the test bearing, the test cage, and the inner diameter surface of the mating planetary gear were observed. The results are shown in Table 1.
-Number of career revolutions: 7600 min ^-1
Pinion rotation number: 9300 min ⁻¹
・ Lubricant: ATF
-Lubricating oil supply amount: 0.03 L / min
・ Oil temperature: 120 ℃
・ Test time: 200 hours ・ Number of test bearings: 6 each

  As shown in Table 1, in Comparative Examples 1 and 2, galling is observed in the test bearing, and in Comparative Example 1, the gear inner diameter surface is greatly deformed. In Comparative Example 2, the electroless nickel-phosphorus coating is largely peeled off. It was. On the other hand, in Example 1, there is no galling and the gear inner diameter surface is not damaged.

  Moreover, the outer diameter surface of the test holder after the test was measured with a non-contact type shape measuring instrument. The measurement results are shown in FIG. 7 for Comparative Example 1, FIG. 8 for Comparative Example 2, and FIG. 9 for Example 1. In each figure, the upper figure shows the surface, and the lower figure shows the cross section.

  As shown in the drawing, no film remains on the surfaces of the test cages of Comparative Examples 1 and 2, and since the surface roughness Ra is a flat surface of about 0.01 μm, no oil sump effect is obtained. . Although the surface roughness before the test was large, it is considered that the surface was worn by sliding with the planetary gear as the counterpart material.

  On the other hand, many deep concave portions and high convex portions remain on the surface of the test cage of Example 1, and a good evaluation result is obtained due to the oil sump effect.

DESCRIPTION OF SYMBOLS 1 Automatic transmission 4-6 Planetary gear mechanism 10 Needle roller bearing 11 Roller 12 Cage

Claims (4)

A needle roller bearing retainer that rotatably supports a planetary gear of a planetary gear mechanism,
It has an annular part and a plurality of pillars extending in the axial direction from the annular part, holds a roller between the neighboring pillars, and is used in an outer ring guide, and has an outer peripheral surface made of iron sulfide. A needle roller bearing retainer comprising a lubricating layer.   The needle roller bearing retainer according to claim 1, wherein the lubricating layer is formed by electrolytic treatment. A needle roller bearing that rotatably supports a planetary gear of a planetary gear mechanism,
3. A needle roller bearing comprising the cage according to claim 1 and being of an outer ring guide type.   4. The needle roller bearing according to claim 3, wherein the needle roller bearing is lubricated with a lubricating oil containing an oily agent.