JPH11101242A - Needle-like roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability and strength of a holder by setting a connecting round part of an annular part and an inside diameter side part of a pocket wall surface of the holder to a value having the specific relationship to a diameter of a needle-like roller. SOLUTION: A connecting round part R of an inside diameter side part of a pocket wall surface 3al of a holder 3 and an inside surface 3bl of an annular part 3b and a connecting round part R of an inside diameter side part of a pocket wall surface 3a2 and an inside surface 3bl, are set to a value having the relationship of (0.2<R/Dr<=0.5) to a diameter Dr of a needle-like roller 4. In a holder 3, a pocket 3a is punched after machining a steel pipe material, but a radial directional dimension Y1 of the pocket wall surface 3al becomes large by the setting of the connecting round parts R, and contact surface pressure of the pocket wall surface 3al with a contact area Y2 of a needle-like roller 4 end surface reduces, and durability can be improved. Since the connecting round parts R become large, a stress concentration on a connecting part of axial directional both side parts 3c2 of a column part 3c and an annular part 3b is mitigated and strength can be enhanced.

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 and a structure for supporting a connecting rod of an engine using the same.

[0002]

2. Description of the Related Art For example, small two-wheeled
In a cycle engine, a bearing ring and a plurality of needle rollers are assembled at a fitting portion between a large diameter boss portion of a connecting rod and a crankpin and a fitting portion between a small diameter boss portion of a connecting rod and a piston pin. Needle roller bearings without them are often used. This is to reduce the size and weight of the engine by taking advantage of this kind of needle roller bearing, which is lightweight, has a small sectional height, and has a large load capacity.

FIG. 3 shows a conventional needle roller bearing B used for supporting a connecting rod. The needle roller bearing B includes a cage 13 in which a plurality of long window-shaped pockets 13a are formed at predetermined circumferential intervals, and a plurality of needle rollers rotatably housed and held in the pockets 13a of the cage 13. 14.

The retainer 13 is an annular body having an annular portion 13b on both sides in the axial direction of the pocket 13a and a column portion 13c continuous on both sides in the circumferential direction with the annular portion 13b. The axial central portion 13c1 of the column portion 13c is recessed so as to have a smaller diameter than the axial side portions 13c2, and the axial central portion 13c1 and the axial side portions 13c2 are continuous via an inclined portion 13c3. Further, the annular portion 13b protrudes in a flange shape toward the inner diameter side so as to have a smaller diameter than the axially both side portions 13c2 of the column portion 13c. Therefore, the vertical cross-sectional shape including the pillar portion 13c of the retainer 13 is substantially M-shaped as a whole.

[0005] The retainer 13 of the needle roller bearing B as described above.
Is formed by shaving a substantially M-shaped basic shape as shown in the figure from a steel pipe material or the like by turning, and then punching (pressing) the pocket 13a. In consideration of the workability of the above, the connecting radius R ′ (formed at the time of cutting out the substantially M-shaped basic shape) with the annular portion 13b shown in an enlarged scale in FIG. (R '/ Dr ≦ 0.2, where Dr is the diameter of the needle rollers 14).

[0006]

By setting the connecting radius R 'small, the workability of punching the pocket 13a is improved, but the radial dimension Y3 (and the needle) of the pocket wall surface 13a1 on the annular portion 13b side of the pocket 13a is improved. Since the area Y4) in contact with the end face of the roller 14 becomes smaller,
This is disadvantageous in terms of the contact surface pressure at the contact portion of the needle roller 14 with the end face. Also, that the connecting radius R 'is small,
It is also disadvantageous in terms of strength (stress concentration) of a connecting portion between the axially both side portions 13c2 of the column portion 13c and the annular portion 13b. On the other hand, these factors relating to the durability and strength of the cage 13 can be eliminated by increasing the thickness of the axial side portions 13c2 of the column 13c, but the weight of the cage 13 increases. And the advantages of this type of needle roller bearing are reduced.

The present invention has been made in view of the tendency of further downsizing and weight reduction of an engine, high speed rotation and high output, and the like, while maintaining the advantages of this type of needle roller bearing, while maintaining its durability and strength, in particular, An object is to improve the durability and strength of the cage.

[0008]

According to the present invention, there is provided a joint R between an inner diameter side portion of a wall surface of a pocket of a retainer and an annular portion.
(Curvature radius) with respect to the diameter Dr of the needle roller is 0.2 <
The value was set to have a relationship of R / Dr ≦ 0.5. By setting the connecting radius R within a range of 0.2 <R / Dr ≦ 0.5, preferably within a range of 0.3 ≦ R / Dr ≦ 0.5, the conventional cage (R ′) /Dr≦0.2, R ′ <
Compared with R), the radial dimension of the pocket wall surface on the annular portion side of the pocket can be made larger, so that the contact surface pressure at the contact portion with the end surface of the needle roller is reduced, and the durability of the cage is improved. . In addition, as the connecting radius R increases, stress concentration at the connecting portion between the pillar portion and the annular portion is reduced, so that the strength of the retainer is improved.

[0009] If R / Dr is less than 0.2, the above effects intended by the present application cannot be obtained. Conversely, if R / Dr exceeds 0.5, the workability at the time of punching the pockets becomes poor. It decreases significantly. Therefore, the connecting radius R is 0.2 <R / Dr ≦
0.5, preferably 0.3 ≦ R / Dr ≦ 0.
Setting the value within the range of 5 is the best in terms of reduction of the contact surface pressure, improvement of the strength of the retainer, and workability of punching pockets.

[0010]

Embodiments of the present invention will be described below.

FIG. 1 shows a crankshaft 1 and a connecting rod 2 of an engine. The crankshaft 1 is disposed inside a crank chamber (not shown), and includes a rotation center shaft 1a, a balance weight 1b, and a crankpin 1c. The crankpin 1c may be formed integrally with the balance weight 1b, or may be formed separately. The connecting rod 2 has a large-diameter boss portion 2a at one end and a small-diameter boss portion 2b at the other end, and the large-diameter boss portion 2a is fitted to the crankpin 1c via a needle roller bearing A in a form described below. You. The small-diameter boss portion 2b of the connecting rod 2 is fitted to a piston pin of a piston (not shown) via a bearing. As the bearing, a needle roller bearing described below can be used.

An air-fuel mixture of gasoline and lubricating oil is fed into the crankcase, and further guided into the combustion chamber of the cylinder according to the vertical movement of the cylinder, where it is burned. The piston moves up and down due to the combustion force of the air-fuel mixture in the cylinder chamber.
The rotation is converted into the rotational motion of the rotation center shaft 1a by the crank pin 1c and the engine rotates. Needle roller bearing A
(And a bearing interposed between the inner peripheral surface of the small diameter boss portion 2b of the connecting rod 2 and the outer peripheral surface of the piston pin of the piston)
It has a role to smoothly guide the operation of the connecting rod 2 accompanying the eccentric rotational movement of c.

FIGS. 2A and 2B show the needle roller bearing A of this embodiment interposed between the inner peripheral surface of the large diameter boss portion 2a of the connecting rod 2 and the outer peripheral surface of the crankpin 1c.
Is shown. The needle roller bearing A includes a cage 3 in which a plurality of long window-shaped pockets 3a are formed at predetermined circumferential intervals.
It comprises a plurality of needle rollers 4 rotatably accommodated and held in a pocket 3a of the retainer 3.

The retainer 3 is an annular body having an annular portion 3b on both sides in the axial direction of the pocket 3a and pillars 3c continuous on both sides in the circumferential direction with the annular portion 3b (the crank pin 1c is integrated with the balance weight 1b). When it is formed, it may have a two-part structure in order to enable mounting.) Column 3c
The axial center portion 3c1 is recessed so as to have a smaller diameter than the axial side portions 3c2, and the axial center portion 3c1 and the axial side portions 3c2 are continuous via the inclined portion 3c3. In addition, the annular portion 3b is formed on both sides 3c in the axial direction of the column portion 3c.
It protrudes in a flange shape toward the inner diameter side so as to have a diameter smaller than 2. Therefore, the vertical cross-sectional shape including the pillar portion 3c of the retainer 3 is substantially M-shaped as a whole.

Inside the annular portion 3b (on the pocket side), there is formed a pocket wall surface 3a1 that comes into contact with the end face of the needle roller 4. As shown in FIG. 3B, the radial dimension of the pocket wall surface 3a1 is Y1, and the area in contact with the end face of the needle roller 4 is Y2. This pocket wall surface 3a
The inner diameter side portion 1 is connected to the inner side surface 3b1 of the annular portion 3b via the connecting radius R.

A pocket wall surface (roller stopper) 3a2 for preventing the needle roller 4 from slipping to the outer diameter side is formed inside the axially opposite side portions 3c2 (pocket side) of the pillar portion 3c. As shown in FIG. 3B, the inner wall surface of the annular portion 3b has an inner diameter portion at one end of the pocket wall surface 3a2 via a connecting radius R (the same size as the connecting radius R of the pocket wall surface 3a1). It is continuous. A pocket wall surface 3a3 that is in contact with the rolling surface of the needle roller 4 on a pitch circle (pitch circle of the needle roller) is formed inside the inclined portion 3c3 of the column portion 3c, and is formed in the axial direction of the column portion 3c. Inside the central portion 3c1, a pocket wall surface (roller stopper) 3a4 for preventing the needle rollers 4 from falling toward the inner diameter side is formed. The thickness of the column 3C is the same as that of the conventional cage.

The inner diameter (diameter) dimension D1 of the annular portion 3b may be at the same level as the inner diameter (diameter) dimension of the axial center portion 3c1 of the column portion 3c. For example, the inscribed circle diameter D0 of the needle roller 4
+ (Diameter Dr of needle roller × 0.15 to 0.2)｝, the inner diameter (diameter) dimension D1 is set to ((diameter) dimension D1 to improve the flowability of lubricating oil to the inside of the bearing and the discharge of contaminants from the inside of the bearing. D0
+ 0.35Dr) ≦ D1 ≦ (D0 + 0.45Dr).

In this embodiment, an inner diameter side portion of the pocket wall surface 3a1 of the retainer 3 and an inner side surface 3b1 of the annular portion 3b are provided.
And the connecting radius R (radius of curvature) between the inner diameter side portion of the pocket wall surface 3a2 and the inner side surface 3b1 of the annular portion 3b are 0.1 mm with respect to the diameter Dr of the needle roller 4. 2 <R / Dr ≦ 0.5, preferably 0.3 ≦
The value is set to have a relationship of R / Dr ≦ 0.5.
More preferable value of (R / Dr) is (R / Dr)
= 3.2, and values in the vicinity thereof (± around 3.2)
(Value within 0.5).

The cage 3 is formed by shaving a steel pipe blank or the like into a substantially M-shaped basic shape as shown in FIG. 1 (at this point, a connecting radius R is also formed), and then the pocket 3a. Is formed by punching (pressing or the like). At this time, since the connecting radius R is set to the above value (R> R ′ with respect to the conventional connecting radius R ′),
Radial dimension Y1 of pocket wall surface 3a1 formed by punching (and contact area Y with end face of needle roller 4)
2) becomes larger than before. Therefore, the contact surface pressure in the contact region Y2 between the pocket wall surface 3a1 and the end surface of the needle roller 4 is reduced as compared with the conventional case, and the durability of the retainer 3 is improved. In addition, as the connecting radius R increases, stress concentration on the connecting portion between the axial side portions 3c2 of the pillar portion 3c and the annular portion 3b is reduced, so that the strength of the retainer 3 is improved. Furthermore, since it becomes difficult for the contamination to stay at the connecting portion, the discharge property of the contamination is improved.

[0020]

The present invention has the following effects.

(1) Compared with the conventional cage, the dimension of the pocket wall surface on the annular portion side of the pocket in the radial direction can be made larger, so that the contact surface pressure at the contact portion with the end face of the needle roller is reduced, and the holding is performed. The durability of the vessel is improved.

(2) Since the connecting radius R is increased, the concentration of stress at the connecting portion between the pillar portion and the annular portion is reduced, so that the strength of the retainer is improved.

(3) Contaminants are less likely to stay at the joint between the pillar portion and the annular portion of the retainer, so that the contaminants can be easily discharged.

(4) Due to the above effects, while maintaining the advantages of this kind of needle roller bearing, that is, light weight, small sectional height, and large load capacity, its durability, strength, and contamination discharge property are maintained. In particular, high durability and reliability can be secured as a supporting bearing for a connecting rod of an engine.

(5) Further, since the connecting rod supporting structure using the needle roller bearing of the present invention as described above is compact and excellent in durability, it is possible to further reduce the size and weight of the engine and increase the speed. Contributes to rotation and high output.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a supporting structure of a connecting rod of an engine.

FIG. 2 is a partial cross-sectional view of a needle roller bearing A according to the embodiment.

FIG. 3 is a partial sectional view of a needle roller bearing B according to a conventional embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankshaft 1c Crank pin 2 Connecting rod 2a Large diameter boss part 2b Small diameter boss part 3 Cage 3a Pocket 3a1 Pocket wall surface 3a2 Pocket wall surface 3b Annular part 3c Column part 4 Needle roller R Connecting radius

Claims (4)

[Claims] 1. A pocket is formed at a plurality of positions in a circumferential direction, an annular portion is formed on both sides in the axial direction of the pocket, a column portion is formed on both sides in the circumferential direction of the annular portion, and a central portion of the column portion in the axial direction is formed. In a needle roller bearing including a retainer recessed to have a smaller diameter than both axial side portions and a plurality of needle rollers accommodated in a pocket of the retainer, an inner diameter side portion of a wall surface of the pocket and A needle roller bearing, wherein a connecting radius R (radius of curvature) with the annular portion has a relationship of 0.2 <R / Dr ≦ 0.5 with respect to a diameter Dr of the needle roller. 2. The needle roller bearing according to claim 1, which is used for supporting a connecting rod of an engine. 3. A pocket for accommodating a needle roller is formed at a plurality of positions in a circumferential direction, and both sides in the axial direction of the pocket are annular portions, and both sides in the circumferential direction are pillar portions continuous with the annular portion, and In a needle roller bearing retainer in which a central portion in the axial direction of the pillar portion is recessed so as to have a smaller diameter than both side portions in the axial direction, a connecting radius R (curvature) between the inner diameter side portion of the wall surface of the pocket and the annular portion Radius) is the diameter D of the accommodated needle roller
A needle roller bearing retainer, wherein r has a relationship of 0.2 <R / Dr ≦ 0.5. 4. A large-diameter boss at one end of a connecting rod is fitted to a crankpin of a crankshaft via a bearing,
In a supporting structure for a connecting rod of an engine in which a small-diameter boss portion at the other end is fitted to a piston pin of a piston via a bearing, a bearing supporting at least one of the large-diameter boss portion and the small-diameter boss portion is arranged in a circumferential direction. Pockets are formed at a plurality of locations, and both sides in the axial direction of the pocket are annular portions, both sides in the circumferential direction are pillar portions continuous with the annular portion, and the central portion in the axial direction of the pillar portion has a smaller diameter than both axial portions. And a plurality of needle rollers housed in a pocket of the cage, and a connecting radius R (radius of curvature) between an inner diameter side portion of a wall surface of the pocket and the annular portion is provided, Needle roller diameter Dr
A connecting roller support structure for an engine, wherein the needle roller bearing has a relationship of 0.2 <R / Dr ≦ 0.5 with respect to