JP2005030468A - Holder for needle roller bearing, and needle roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holder for a needle roller bearing manufacturable with improved reliability, and to provide a needle roller bearing. <P>SOLUTION: When the needle roller bearing 10 is assembled between a pinion shaft (an inner ring) 4e and a planetary gear (an outer ring) 4c, a clearance Δ1 between a guide part 12d of a cage bar part 12b and the roller 11 held by the guide part becomes smaller than a clearance Δ2 between the cage bar part 12b and a central part of the roller 11. In the case of relatively moving holder 12, to which strong centrifugal force is applied, and the roller 11 at a rolling possible position, since the roller 11 abuts on the guide part 12d on a root side of the cage bar part 12, stress applied to the root of the cage bar part 12 becomes smaller than the case of abutting on a central part 12c. With this structure, fatigue fracture of the holder 12 can be avoided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a needle roller bearing retainer and a needle roller bearing, and more particularly to a needle roller bearing retainer and a needle roller bearing capable of improving reliability.
[0002]
[Prior art]
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. When used for supporting, it is preferable because it contributes to the compactness of the automatic transmission on which it is mounted (see Patent Document 1).
[Patent Document 1]
JP 2002-349647 A [Patent Document 2]
Japanese Patent Laid-Open No. 9-151944
[Problems to be solved by the invention]
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. .
[0004]
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. Centrifugal force combining them is applied to the needle roller bearing. Therefore, when the needle roller bearing is provided with a cage, a large centrifugal force is applied to the cage, an excessive stress is generated, which may cause breakage.
[0005]
In particular, the so-called M-type cage has a shape in which the central portion of the column portion is reduced in diameter. In such a shape, the central portion is more than the base of the column portion. However, since the roller base is close to the outer peripheral surface of the roller, the base of the column where the center of the roller comes into contact with the roller is subjected to strong repetitive stress during the operation of the needle roller bearing. .
[0006]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a needle roller bearing retainer and a needle roller bearing with improved reliability.
[0007]
[Means for Solving the Problems]
The cage of the needle roller bearing of the present invention is
A pair of annular portions arranged at intervals in the axial direction, a plurality of pillar portions intermittently arranged in the circumferential direction, each end portion being connected to both annular portions, and the circumferential direction Is located between each of the adjacent pillars, and is provided with a plurality of pockets for holding the rollers in a freely rollable manner. In a cage for needle roller bearings, which are subjected to machining with a cylindrical surface as an outer peripheral surface by welding the annular portions facing each other,
When the needle roller bearing is assembled between the inner ring and the outer ring, the clearance between the first portion of the column portion and the roller held by the cage is the first portion of the column portion. The clearance is smaller than the gap between the second portion on the center side in the axial direction and the roller.
[0008]
[Action]
The cage of the needle roller bearing of the present invention has a pair of annular portions arranged at intervals in the axial direction, and is intermittently arranged in the circumferential direction, and both ends are connected to both annular portions. And a plurality of pockets, and a plurality of pockets for holding the rollers in a rollable manner between the pillars adjacent to each other in the circumferential direction. In the needle roller bearing retainer formed by punching and forming each of these pockets on a plate and then rounding into a cylindrical shape, welding the opposite annular portions, and machining the outer peripheral surface to a cylindrical surface, When the needle roller bearing is assembled between the inner ring and the outer ring, the clearance between the first portion of the column portion and the roller held by the retainer is less than the first portion of the column portion. It is smaller than the clearance between the second portion on the center side in the axial direction and the roller. Therefore, when the needle roller bearing is in operation, the roller contacts the base side of the column portion, so that the moment force applied to the column portion is compared with the conventional configuration in which the center portion of the column portion contacts. Therefore, the stress at the base of the column part can be suppressed to be small, and fatigue failure can be suppressed.
[0009]
When assembling the needle roller bearing, rollers are loaded in the pocket of the cage from the inside in the radial direction. By doing so, a unique configuration of the present invention can be obtained. You may shape | mold so that the center part outer-diameter side width | variety of a holder | retainer pillar part may become small in order to prevent roller rolling. Moreover, you may perform a pocket punching process, a cutting process, etc. so that the width | variety of the center part of a pillar part may be narrowed without using a roller anti-barre part.
[0010]
Further, the cage is preferably subjected to a carbonitriding process or a carburizing process.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of an automatic transmission 1 for a vehicle including a needle roller bearing according to the present embodiment. In FIG. 1, torque output from the crankshaft 2 of the engine is transmitted through a torque converter 3 and further decelerated to a plurality of stages through a plurality of planetary gear mechanisms 4, 5, 6, etc. The power is output to a wheel (not shown) via the differential gear 7 and the drive shaft 8.
[0012]
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.
[0013]
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. 3A, a large reduction ratio can be obtained by setting the sun gear 4b to the drive side, the planetary gear 4c (carrier) to 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.
[0014]
FIG. 4 is a view showing the needle roller bearing of the present embodiment incorporated in a 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 cage 12 that holds them. In the pinion shaft 4e, there is formed an oil passage 4f extending along the axis from the right side in FIG. 4 and generally passing through the outer peripheral surface or the inner peripheral surface at the center. The cage 12 is used for outer ring guidance.
[0015]
FIG. 5 is a perspective view of the cage of the needle roller bearing according to the present embodiment. 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 part 12b has a central part 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 the diameter is increased from both sides in the axial direction of the central part 12c to the annular part 12a. The part is a guide part 12d. The cage 12 having such a shape is called an M-type cage.
[0016]
At the time of manufacturing the cage 12 of the present embodiment, as shown in FIG. 10, the pockets p are punched and formed at equal intervals on the band-shaped metal plate m, and then rolled into a cylindrical shape. The end portions e1 and e2 to be welded are formed to form a pair of annular portions 12a (FIG. 5), and machining is performed with the outer peripheral surface being a cylindrical surface. Since carburizing and quenching is subsequently performed, the cage strength and seizure resistance are excellent.
[0017]
FIG. 6 is a view of the cage 12 shown in FIG. 5 taken along the line VI-VI and viewed in the direction of the arrow, but FIG. 6A shows that the angular tolerance of the column portion 12b is a reference value. FIG. 6B shows the maximum angle tolerance of the column portion 12b, and FIG. 6C is an enlarged view of the configuration of FIG. The roller 11 indicated by a dotted line is in a rollable position sandwiched between the pinion shaft 4e and the planetary gear 4c, and the roller 11 indicated by a solid line is in a free state before being assembled to the planetary gear mechanism.
[0018]
In FIG. 6, the guide portion 12d is plastically deformed by being pressed from the outside in the radial direction after assembling the roller 11 in the pocket portion formed between the adjacent column portions 12b in order to prevent roller rolling. The taper surface 12f has a circumferential width that increases outward in the radial direction. In the present embodiment, the cross section of the central portion 12c is rectangular.
[0019]
In this embodiment, as shown in FIG. 6C, when the needle roller bearing 10 is assembled between the pinion shaft (inner ring) 4e and the planetary gear (outer ring) 4c, the guide of the column portion 12b is guided. The clearance Δ1 between the portion (first portion) 12d and the end portion side of the roller 11 to be held is smaller than the clearance Δ2 between the central portion (second portion) 12c of the column portion 12b and the central portion side of the portion 11b. It has become. Therefore, in the rollable position indicated by the dotted line, when the cage 12 or 11 that receives a strong centrifugal force is relatively moved as described above, the roller 11 always contacts the guide portion 12d on the base side of the column portion 12b. Compared with the case where it hits the central portion 12c, the stress acting on the base of the column portion 12b is reduced. Thereby, fatigue failure of the cage 12 can be avoided. Furthermore, the M-shaped cage 12 has a shape with a reduced diameter at the central portion 12c of the column portion 12b, and the central portion 12c has a portion in which the circumferential width on the axis side of the cage 12 is widened. Therefore, a shape that can be easily incorporated into the inner ring can be obtained.
[0020]
Here, in the cage 12 in which the roller 11 is incorporated, a predetermined play is given so that the roller 11 can move in the pocket. This play is determined by the amount of roller protrusion and the amount of roller fall. The amount of roller protrusion refers to the amount of outward protrusion in the radial direction when the roller 11 contacts the tapered surface 12f of the guide portion 12d, and the roller drop amount refers to when the roller 11 contacts the side surface of the central portion 12c. This is the amount of protrusion inward in the radial direction. However, as shown in FIG. 6C, when Δ1 <Δ2, there is a problem that the amount of roller drop increases because the clearance Δ2 increases. Such a problem will be described below by comparing the cage shown in FIG. 6 (a) with the cage shown in FIG. 6 (b).
[0021]
As described above, in the case of the cage 12 formed by welding as in the present embodiment, the pocket 12 is rounded into a cylindrical shape after the pocket window processing, so that the cross-sectional shape of the central portion 12c is rectangular. Cross section. In the case of a rectangular cross section, the roller drop amount greatly changes depending on the angle tolerance. To prevent this, it is necessary to narrow the allowable tolerance range including the dimensional tolerance of the central portion 12c, thereby increasing the cost. In order to prevent this, there is an idea that the central portion 12c is positioned more radially inward, but there is a risk that the flow of the lubricant toward the axial direction may be hindered.
[0022]
In particular, as in the case of the cage 12 shown in FIG. 6A, when the angle tolerance of the column portion 12b is a reference value, even if the roller drop amount δ1 is within the reference range, FIG. As in the cage 12 shown, when the angle tolerance of the column portion 12b becomes the maximum value within the allowable range, the roller drop amount δ2 may be out of the reference range. When the roller drop amount is out of the reference range, when the needle roller bearing 10 is assembled into the pinion shaft 4e, the roller 11 becomes in the way and the assemblability deteriorates. Such a problem can be solved by the second embodiment described below.
[0023]
FIG. 7 is a cross-sectional view similar to FIG. 6 of the cage 112 according to the second embodiment. FIG. 7A shows the angular tolerance of the column portion 112b as a reference value, and FIG. ) Is the maximum value of the angle tolerance of the column part 112b within the allowable range. As shown in FIG. 7, the cage 112 of the present embodiment has a tapered shape in which the cross-sectional shape of the central portion surface 112 c increases in the circumferential width as it goes inward in the radial direction of the cage 112. Such a central portion 112c can be obtained by forming the retainer 112 and then scraping the central portion 112c or pressing it from the inside in the radial direction for plastic deformation. Since other configurations are the same as those in the above-described embodiment, the description thereof is omitted.
[0024]
As shown in FIG. 7, since the cross-sectional shape of the central portion 112c is tapered, the roller 11 in the free state has a radius more than that of the embodiment of FIG. 6 when contacting the side surface of the central portion 112c. The direction will be outward. That is, when the angle tolerance of the column portion 112b is a reference value as in the cage 112 shown in FIG. 7A, a roller drop amount δ3 smaller than the roller drop amount δ1 shown in FIG. 6A is obtained. Even when the angle tolerance of the column part 112b becomes the maximum value within the allowable range as in the cage shown in FIG. 7B, the roller drop amount δ2 shown in FIG. A small roller drop amount δ4 can be obtained, and the roller drop amount can be within an allowable sub-range without driving the central portion 112c inward in the radial direction.
[0025]
FIG. 8 is a cross-sectional view similar to FIG. 7 of the cage 212 according to the third embodiment. In the cage 212 of the present embodiment, the shape of the central portion 212c of the column portion 212b is different from that of the embodiment shown in FIG. More specifically, as for the cross-sectional shape of the central portion 212c, only the radially outer side is a tapered shape, and the radially inner side is a parallel side surface. Since other configurations are the same as those in the above-described embodiment, the description thereof is omitted. According to the present embodiment, the roller 11 can be easily assembled.
[0026]
FIG. 9A is an axial cross-sectional view of the cage 312 according to the fourth embodiment, and FIG. 9B shows the cage 312 shown in FIG. FIG. 9C is a diagram of the cage 312 shown in FIG. 9A cut along the line CC and viewed in the arrow direction. In the cage 312 of the present embodiment, the cross-sectional shape of the central portion of the column portion 312b is not uniform in the axial direction unlike the embodiment shown in FIG. More specifically, the central portion of the column portion 312b has two tapered portions 312c having a tapered cross-sectional shape and a rectangular parallel portion 312c ′ formed therebetween. According to this configuration, since the parallel portion 312c ′ is provided, the radial clearance of the cage 312 is further increased compared to the case where the central portion is entirely the tapered portion 312c, and the supply is supplied from the oil passage 4f of the pinion shaft 4e. This has the effect of increasing the flow of lubricant. Since other configurations are the same as those in the above-described embodiment, the description thereof is omitted.
[0027]
The present invention has been described with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate.
[0028]
【The invention's effect】
The cage of the needle roller bearing of the present invention has a pair of annular portions arranged at intervals in the axial direction, and is intermittently arranged in the circumferential direction, and both ends are connected to both annular portions. And a plurality of pockets, and a plurality of pockets for holding the rollers in a rollable manner between the pillars adjacent to each other in the circumferential direction. In the needle roller bearing retainer formed by punching and forming each of these pockets on a plate and then rounding into a cylindrical shape, welding the opposite annular portions, and machining the outer peripheral surface to a cylindrical surface, When the needle roller bearing is assembled between the inner ring and the outer ring, the clearance between the first portion of the column portion and the roller held by the retainer is less than the first portion of the column portion. It is smaller than the clearance between the second portion on the center side in the axial direction and the roller. Therefore, when the needle roller bearing is in operation, the roller contacts the base side of the column portion, so that the moment force applied to the column portion is compared with the conventional configuration in which the center portion of the column portion contacts. Therefore, the stress at the base of the column part can be suppressed to be small, and fatigue failure can be suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an automatic transmission for a vehicle including a needle roller bearing according to an embodiment.
FIG. 2 is an exploded view of the planetary gear mechanism 4;
FIG. 3 is a diagram illustrating an operation principle of a planetary gear mechanism.
FIG. 4 is a view showing the needle roller bearing according to the first embodiment incorporated in a planetary gear mechanism.
FIG. 5 is a perspective view of a cage of a needle roller bearing.
6 is a view of the cage 12 shown in FIG. 5 taken along line VI-VI and viewed in the direction of the arrow.
FIG. 7 is a radial cross-sectional view of a cage for a needle roller bearing according to a second embodiment.
FIG. 8 is a radial sectional view of a cage for a needle roller bearing according to a third embodiment.
FIG. 9 is a view showing a cage for a needle roller bearing according to a fourth embodiment.
10 is a view showing a material of the cage according to the first embodiment in a state where a pocket portion is punched out. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Automatic transmission 4-6 Planetary gear mechanism 10 Needle roller bearing 11 Roller 12, 112, 212, 312 Cage

Claims (3)

A pair of annular portions arranged at intervals in the axial direction, a plurality of pillar portions intermittently arranged in the circumferential direction, each end portion being connected to both annular portions, and the circumferential direction Is located between each of the adjacent pillars, and is provided with a plurality of pockets for holding the rollers in a freely rollable manner. In a cage for needle roller bearings, which are subjected to machining with a cylindrical surface as an outer peripheral surface by welding the annular portions facing each other,
When the needle roller bearing is assembled between the inner ring and the outer ring, the clearance between the first portion of the column portion and the roller held by the cage is the first portion of the column portion. A retainer for a needle roller bearing, characterized by being smaller than a clearance between the second portion on the center side in the axial direction and the roller. The needle roller bearing cage according to claim 1, wherein the cage is subjected to carbonitriding or carburizing treatment. A needle roller bearing comprising the cage according to claim 1 and a roller held by the cage.

Images