JP2000074072A - Needle roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of a skew produced on a needle roller, to secure load capacity of a bearing and to extend longevity of the bearing. SOLUTION: This needle roller bearing 41 to support a planetary gear 5 free to rotate against a carrier 6 is roughly constituted of a cylindrical holer 42 made of a resin material and needle rollers 48, 48 stored in a pocket 45 formed on the holder 42 and separated into two pieces in the axial direction. Consequently, bending stress due to a skew is reduced by reducing length of the needle roller 48. In the meantime, load capacity is secured as two pieces of the needle type rollers 48 become one piece of the needle roller. Accordingly, longevity of the needle roller bearing 41 is extended by reducing abrasion of the needle rollers 48, a rolling contact surface, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle roller bearing suitable for use in, for example, a planetary gear reduction device having a portion for receiving low-speed large torque.

[0002]

2. Description of the Related Art Generally, among bearings that rotatably support a shaft, a roller bearing using a plurality of rollers as rolling elements has a retainer formed in a substantially cylindrical shape as a whole, and the retainer is rotatable on the retainer. And a plurality of rollers that are held in the vehicle.

Therefore, a case where the needle roller bearing according to the prior art as described above is used for a planetary gear reduction mechanism of a turning device shown in FIG. 5 will be described as an example.

[0004] Reference numeral 1 denotes a planetary gear reduction mechanism. The planetary gear reduction mechanism 1 includes a cylindrical housing 3 having an internal gear 2 formed on the entire inner circumference and a sun gear housed in the housing 3. 4, a plurality of planetary gears 5 (only one is shown) that mesh with the sun gear 4 and the internal gear 2 of the housing 3 and revolve around the sun gear 4 while rotating, and the respective planetary gears 5 will be described later. A carrier 6 is rotatably supported by using a needle roller bearing 8 or the like.

The carrier 6 comprises internal teeth 6A formed on the inner peripheral side, an upper pin support 6B and a lower pin support 6C opposed to each other with the planetary gear 5 interposed therebetween. The pin 7 is supported between the support 6B and the lower pin support 6C.

Reference numeral 8 denotes a needle roller bearing provided between the planetary gear 5 and the pin 7 and rotatably supporting the planetary gear 5 with respect to the carrier 6. The needle roller bearing 8 has a planetary gear on its outer peripheral side. 5, a cylindrical retainer 9 having a pin 7 inserted through the inner peripheral side thereof, and a plurality of needle rollers rotatably held in the retainer 9 at equal intervals. 1
And 5.

Here, the configuration of the needle roller bearing 8 will be described with reference to FIGS.

The retainer 9 is formed as a cylindrical body, and has a pair of annular portions 10 spaced apart in the axial direction.
0, and each annular portion 1
A plurality of struts 11 connecting between the zeros, a plurality of pockets 12 arranged between the struts 11 and formed as rectangular openings for accommodating the needle rollers 15, and a plurality of needle rollers. In order to hold the rotatable member 15 rotatably, it is composed of a plurality of protrusions 13 protruding from the inner peripheral side and the outer peripheral side of the side surface 11A of each column 11 facing the pocket 12 therebetween.

An oil path 14 is formed between the side surface 11A of each column 11 and the needle roller 15, and the oil path 14 allows lubricating oil to easily flow into the gap between the pocket 12 and the needle roller 15. The lubricating property is increased by circulating the oil.

Then, the needle roller 1 held by the holder 9 is
The planetary gear 5 revolves around the pin 7 while rotating between the planetary gear 5 and the pin 7, so that the planetary gear 5 rotates smoothly with respect to the pin 7.

Reference numerals 16 and 16 denote annular sliding plates provided between the axial ends of the needle roller bearing 8 and the upper pin support 6B and the lower pin support 6C of the carrier 6, respectively. The moving plate 16 improves the slidability of the axial end surface of the needle roller bearing 8 and assists the smooth rotation of each planetary gear 5 with respect to the carrier 6.

Reference numeral 17 denotes an output shaft rotatably supported in the housing 3 via a bearing or the like (not shown). The output shaft 17 is sandwiched between a sun gear 4 and a plate 18 as a sliding plate.
And are arranged coaxially. A tooth portion 17A is formed on the outer periphery of the upper end side of the output shaft 17, and the tooth portion 17A meshes with the internal teeth 6A of the carrier 6.

In the planetary gear reduction mechanism 1 of the last stage configured as described above, when the sun gear 4 is rotated by the planetary gear reduction mechanism of the preceding stage by driving a motor (not shown), each planetary gear 5 is rotated by the sun gear 4. Revolves around the sun gear 4 while rotating between the inner gear 2 of the housing 3 and
As the respective planetary gears 5 revolve, the carrier 6 rotates about the sun gear 4. Thus, the rotation of the output shaft of the motor is reduced and transmitted to the output shaft 17 connected to the internal teeth 6A of the carrier 6 using the tooth portions 17A, and the torque of the output shaft 17 increases according to the reduction ratio. I do.

[0014]

By the way, the planetary gear reduction mechanism 1 located at the final stage outputs a torque increased by reducing the output of the motor. Uses a gear with a long tooth width. Along with this, a needle roller bearing 8 that rotatably supports the planetary gear 5 on the pin 7 also needs to have a high load capacity.

In general, the load capacity of the needle roller bearing 8 is defined by JIS B 1518 (a method of calculating the dynamic load rating and the rated life of the rolling bearing), and is determined by the basic dynamic load rating and the basic static load rating. ing. As one means for increasing the basic dynamic load rating and the basic static load rating, it is conceivable that the needle roller 15 may be a roller having a longer overall length than its diameter.

However, when a long needle roller 15 is used, a moment is easily generated as long as the needle roller 15 is long.
The phenomenon that the needle rollers 15 are inclined with respect to the normal rotation axis (hereinafter, referred to as
Skew). Therefore, when skew occurs in the needle rollers 15, the needle rollers 15
Are in contact with the inner peripheral surface of the planetary gear 5 to be in a bridge state.
When a load P0 in the radial direction is applied from the
It is also generally known that a bending moment is generated at 5 and a bending stress .sigma.

[0017]

(Equation 1) Here, L: length of needle roller 15 [mm] D: diameter of needle roller 15 [mm]

As can be seen from Equation 1, the bending stress σ
Is proportional to the length L of the needle roller 15, so that a large bending stress σ is likely to be generated in the needle roller 15, and the needle roller 15 may be worn out early.

Further, a force corresponding to the bending stress .sigma. Is applied to the rolling surfaces such as the inner peripheral side of the planetary gear 5 and the outer peripheral surface of the pin 7 which come into contact when the needle rollers 15 rotate. Wear may also occur on the moving surface.

Here, in order to solve the problem of skew generated in the needle rollers 15, it is conceivable to use a needle roller bearing 21 instead of the needle roller bearing 8 as shown in FIG. The needle roller bearing 21 has a large number of pockets 23A, 23B formed over the entire circumference at positions axially separated by annular portions 22A, 22B, 22C and columns (not shown) which are axially separated. A retainer 22 having
And a needle roller 24 disposed in the pockets 23A and 23B of the retainer 22. The length of the needle roller 24 is shorter than that of the needle roller 15. In the needle roller bearing 21, a pocket is divided into pockets 23A and 23B by an annular portion 22B located at an axially intermediate position, and needle rollers 24 are arranged in the pockets 23A and 23B.

As another means, as shown in FIG. 9, needle roller bearings 31A, 31A are used instead of needle roller bearings 8.
It is also conceivable to use B. One needle roller bearing 31
A is a holder 32A which is substantially half the axial length of the holder 9 and has a large number of pockets 33A over the entire circumference;
A needle roller 34A held in each pocket 33A of the retainer 32A, and the other needle roller bearing 31B
Also, similarly to the needle roller bearing 31A, a retainer 32B having a pocket 33B and a pocket 33 of the retainer 32B are provided.
B, and the needle rollers 34B held in B. Then, the needle roller bearings 31A and 31B are combined to be applied instead of the needle roller bearing 8.

However, when the needle roller bearings 21 and 31 are used in place of the needle roller bearing 8 as described above, the length of the needle rollers 24 and 34 is shortened. As shown in FIG. 1, although the bending stress σ due to skew can be reduced, there is a problem that the basic dynamic load rating and the basic static load rating of the bearing are reduced. In addition, there is a problem that the cost increases in any case as compared with the case where the needle roller bearing 8 according to the related art is used alone.

The present invention has been made in view of the above-mentioned problems of the prior art, and provides a needle roller bearing capable of reducing the influence of skew generated in the needle rollers and ensuring a large load capacity of the bearing. It is intended to be.

[0024]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a retainer which is formed as a cylindrical body and has a large number of pockets all around the circumference, and each of which has a pocket therein. In a needle roller bearing comprising a rotatably held needle roller, the needle rollers are arranged so as to be separated into a plurality in the axial direction of each pocket.

With such a configuration, the length of each of the needle rollers separated in the pocket in the axial direction can be reduced, and the occurrence of skew in the needle rollers can be reduced. Moreover, even if skew occurs in the needle rollers,
The bending stress of each needle roller can be reduced. Also,
Since the needle rollers separated in the axial direction are arranged in one pocket, each needle roller can be regarded as a roller having a longer effective roller length than the prior art, and receives a low speed and large torque. A sufficient load capacity can be secured.

According to the second aspect of the present invention, the retainer includes a pair of annular portions which are spaced apart in the axial direction, and a plurality of annular portions which are arranged at intervals between the annular portions and connect the annular portions. The support part is constituted by pockets provided between the support parts to accommodate the needle rollers, and the retainer is formed by integrally molding the annular part and the support part using a resin material. is there.

As described above, the cage made of a resin material is
The cage can be integrally formed by injection molding, and the retainer can be easily formed.

According to the third aspect of the present invention, a plurality of projections for separately holding a plurality of needle rollers are provided on the side surface of each of the columns facing each other across the pocket.

[0029] With this configuration, the projections located on the side surfaces of the respective support portions can rotate the needle rollers in the pockets while securing an oil path between the side surfaces and the needle rollers. Can be held. In addition, when the cage is formed from a resin material, each of the protrusions can be easily provided.

According to a fourth aspect of the present invention, two needle rollers are held in each pocket.

Thus, when the number of the needle rollers is two, the load capacity of the bearing can be secured as compared with the case where the number of the needle rollers is three or more.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS. In the embodiments, the same components as those of the above-described conventional technology are denoted by the same reference numerals, and description thereof will be omitted.

Reference numeral 41 denotes a needle roller bearing according to the present embodiment. The needle roller bearing 41 can rotate each planetary gear 5 with respect to the pin 7 supported on the carrier 6 constituting the planetary gear reduction mechanism 1. It is to support. The needle roller bearing 41 is substantially the same as the needle roller bearing 8 shown in FIG.
An outer peripheral side is fitted into a bearing hole 5A of the planetary gear 5 and a pin 42 is inserted into the inner peripheral side, and a plurality of needles rotatably held in the retainer 42 at equal intervals. And a roller 48.

Numeral 42 denotes a cylindrical retainer which constitutes the needle roller bearing 41. The retainer 42 is provided between a pair of annular portions 43 which are spaced apart in the axial direction and each annular portion 43. And a plurality of support portions 44 connecting the annular portions 43 with each other, and each of the support portions 44 is located between each of the support portions 44 and is separated into two in the axial direction. 4
A large number of pockets 45 formed as rectangular openings for accommodating 8, 48, and respective strut portions 44 opposed to each other with the pocket 45 interposed therebetween to rotatably hold the two needle rollers 48, 48. And a plurality of protrusions 46 protruding from the inner peripheral side and the outer peripheral side of the side surface 44A. Also,
Each of the protrusions 46 is provided on the inner peripheral side and the outer peripheral side of the side surface 44A so as to be separated by four in the axial direction, and two needle rollers 48,
48 are kept separately.

An oil path 47 is formed between the side surface 44A of the support 44 and the needle roller 48, and these oil paths 47 are formed.
As a result, the lubricating oil is easily circulated in the gap between the pocket 45 and the needle roller 48, thereby improving lubricity.

Are needle rollers housed in the respective pockets 45, and the respective needle rollers 48 are arranged in the pocket 45 so as to be separated into two in the axial direction. As shown in FIG. 2, the two needle rollers 48, 48 arranged in the axial direction are retained by the retainer 42 in a state where they are individually prevented from being pulled out by the respective projecting portions 46.

As shown in FIG. 1, the needle roller bearing 41 is inserted into the bearing hole 5A of the planetary gear 5, and supports the planetary gear 5 in which the needle roller bearing 41 is incorporated, by supporting the upper pin of the carrier 6. After the sliding plate 16 is vertically arranged between the portion 6B and the lower pin supporting portion 6C, the pins 7 are press-fitted from the upper pin supporting portion 6B to the lower pin supporting portion 6C, thereby making each The planetary gear 5 is assembled to the carrier 6 using the needle roller bearing 41 and the pin 7.

The needle roller bearing 41 according to the present embodiment is
With the configuration as described above, there is no particular difference in the planetary gear reduction device including the needle roller bearing 41.

However, according to the present embodiment, the holder 4
Since the needle rollers 48 separated into two in the axial direction are arranged in the pocket 45 formed in the second roller 2, each needle roller 48 is provided one by one.
Can be shortened, and the effect of skew generated on one needle roller 48 can be reduced. In addition, even if the skew occurs in the needle rollers 48, the bending stress of each needle roller (see Equation 1 above) can be reduced as compared with the prior art. Thus, the wear of the needle rollers 48 and the wear of the rolling surfaces can be reduced, and the life of the needle roller bearing 41 can be extended.

As described in the prior art, the load capacity of the needle roller bearing 41 is defined by the basic dynamic load rating and the basic static load rating.
In this configuration, two needle rollers 48 which are separated in the axial direction into one pocket 45 are arranged. This allows
After securing this load capacity, the needle roller bearing 41 can be realized, and the needle roller bearing 41 is used for the planetary gear reduction mechanism 1 that is the last stage of the planetary gear reduction device that receives low-speed and large torque. Can be used.

Further, since the retainer 42 is made of resin, the retainer 42 can be integrally formed by injection molding, and the manufacturing cost of the needle roller bearing 41 can be greatly reduced. In addition, the number of the protrusions 46 for accommodating and holding the two separated needle rollers 48 in the pocket 45 can be easily increased.

Next, FIGS. 3 and 4 show first and second modifications of the retainer 42 according to the above-described embodiment. In addition,
In each modified example shown in FIGS. 3 and 4, the same components as those of the retainer 42 shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.

In the first modified example shown in FIG. 3, reference numeral 51 denotes a retainer, and three retainers 51 are provided on the inner peripheral side and the outer peripheral side of the side surface 44A of each column 44 constituting the retainer 51, respectively. Protrusions 52 are protruded from each other, and an oil path 53 is formed between each protrusion 52, the side surface 44 </ b> A of the support 44 and the needle roller 48.

When the cage 51 according to the first modified example is used for the needle roller bearing 41, each needle roller 4
8 can be separately held in the pockets 45, and the same operation and effect as when the retainer 42 according to the embodiment is used can be obtained. In addition, by reducing the number of projections 52, a large oil passage 53 can be secured, and the lubricating oil can be efficiently circulated.

In the second modification shown in FIG.
Numeral 61 denotes a retainer, and each column 44 constituting the retainer 61
On the inner peripheral side of the side surface 44A, three protruding portions 62 are provided in the axial direction, and on the outer peripheral side of the side surface 44A, two protruding portions 63 are provided in the axial direction. An oil path 64 is formed between each of the projections 62 and 63, the side surface 44A of the support 44, and the needle roller 48.

When the cage 61 according to the second modified example is used for the needle roller bearing 41, each needle roller 4
8 can be separately held in the pockets 45, and the same operation and effect as when the retainer 42 according to the embodiment is used can be obtained. In addition, by reducing the number of the protrusions 62 and 63, a large oil passage 64 can be secured, and the lubricating oil can be circulated more efficiently.

In the embodiment, the needle rollers 48 which are separated into two parts in the axial direction in the pocket 45 are arranged. However, the present invention is not limited to this. Needless to say, needle rollers separated into individual pieces may be arranged. However, the number of parts to be separated may be such that the load capacity of the bearing does not decrease.

In the embodiment, the retainer of the needle roller bearing used for the portion supporting the planetary gear of the planetary gear reduction mechanism has been described as an example. However, the present invention is not limited to this. For example, the present invention can be widely applied to a needle roller bearing that rotatably supports a rotating body such as a rotating shaft, a support pin, and a rotating rod.

[0049]

As described above in detail, according to the first aspect of the present invention, the length of each of the needle rollers separated in the axial direction in the pocket can be reduced, and skew occurs in the needle rollers. Can be reduced. Moreover, even if skew occurs in the needle rollers, the bending stress of each needle roller can be reduced. In addition, by placing the separated needle rollers in one pocket, the length of the needle rollers can be regarded as a longer roller compared to the conventional technology, and a load capacity sufficient to receive low-speed large torque is secured. can do. Thus, wear on the needle rollers and the rolling surfaces of the needle rollers can be eliminated, and smooth rotation of the members supported via the needle roller bearings can be compensated for a long time.

According to the second aspect of the present invention, since the annular portion and the support portion are integrally formed of a resin material, they can be formed by injection molding, and the manufacturing cost of the roller bearing can be reduced.

According to the third aspect of the present invention, since a plurality of protrusions for separately holding a plurality of needle rollers are provided on the side surface of each of the pillar portions facing each other with the pocket interposed therebetween, the side surfaces and the needle rollers are separated from each other. After securing an oil path between the needle rollers, the needle rollers can be rotatably held in the pocket. In addition, when the cage is formed of a resin material, the respective protrusions can be easily formed integrally, and the manufacturing cost of the bearing can be reduced.

According to the fourth aspect of the present invention, since the two needle rollers held in the pocket are formed, the load capacity of the bearing can be ensured as compared with the case where three or more needle rollers are formed. Can be.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state in which a needle roller bearing according to an embodiment is used in a planetary gear reduction mechanism.

FIG. 2 is an enlarged longitudinal sectional view showing a retainer used for the needle roller bearing in FIG.

FIG. 3 is an enlarged longitudinal sectional view showing a first modified example of the cage according to the embodiment.

FIG. 4 is an enlarged vertical sectional view showing a second modified example of the retainer according to the embodiment.

FIG. 5 is a longitudinal sectional view showing a state in which a conventional needle roller bearing is used for a planetary gear reduction mechanism.

6 is a perspective view showing a retainer used for the needle roller bearing in FIG.

FIG. 7 is an enlarged vertical sectional view showing a retainer used for a needle roller bearing.

FIG. 8 is a longitudinal sectional view showing a state in which a needle roller bearing according to another conventional technique is used in a planetary gear reduction mechanism.

FIG. 9 is a longitudinal sectional view showing a state where a needle roller bearing according to still another conventional technique is used in a planetary gear reduction mechanism.

[Explanation of symbols]

 41 Needle roller bearings 42, 51, 61 Cage 43 Annular part 44 Support part 44A Side surface 45 Pocket 46, 52, 62, 63 Projection part 48 Needle roller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinobu Yamamoto 650, Kandate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Inside the Tsuchiura Plant (72) Inventor Takeshi Shibukawa 650, Kandamachi, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd.F-Term in the Tsuchiura Plant (reference)

Claims (4)

[Claims] 1. A needle roller bearing comprising a retainer formed as a cylindrical body and having a large number of pockets all around its circumference, and needle rollers each rotatably held in a pocket of the retainer. The needle roller bearing is characterized in that the needle rollers are arranged so as to be separated into a plurality in the axial direction of each pocket. 2. The retainer includes a pair of annular portions that are spaced apart in the axial direction, a plurality of struts disposed between the annular portions and connecting the annular portions, and the needle. 2. The retainer according to claim 1, further comprising pockets provided between the columns to accommodate the rollers, wherein the retainer is formed by integrally molding the annular portion and the columns using a resin material. Needle roller bearing. 3. The needle roller according to claim 1, wherein a plurality of protrusions for separately holding the plurality of needle rollers are provided on a side surface of each of the pillar portions facing the pocket. bearing. 4. The needle roller bearing according to claim 1, wherein the needle rollers held in each pocket are constituted by two pieces.