JP2560173Y2 - Needle roller bearing device for connecting rod - Google Patents

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 for a connecting rod small end provided between a small end of a connecting rod and a piston pin, for example, in an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, with an increase in the speed of an internal combustion engine, it has been attempted to mount a rolling bearing on a connecting portion between a connecting rod and a piston pin. As this rolling bearing, a needle roller bearing (cage and roller) having no inner and outer races using a piston pin as an inner race and a large end or a small end of a connecting rod as an outer race is employed. Normally, both the needle rollers and the cage are formed of a metal material. The needle rollers are made of SUJ2 or the like.
M and other materials. Recently, attempts have been made to make the large end needle rollers from ceramics.

[0003]

By the way, the needle roller bearing used for the above-mentioned small end portion is required to be used at a high speed swing , to be subjected to a high load due to an explosion in a combustion chamber, and to be used in a high temperature atmosphere. Because it is used under severe conditions such as being exposed to light and the rotational speed being fluctuated by the crank mechanism, various damages occur to the needle rollers at an early stage and the seizure life is shortened. Has occurred.

Further, since both the retainer and the needle rollers are made of metal and have a large total weight, the rotational balance in the high-speed rotation range becomes unstable, which hinders the high-speed rotation of the engine. It is pointed out that it is easy.

In order to solve such a problem, a needle roller bearing made of ceramics used for the large end has been considered. However, the small end does not have a rotational movement like the large end. Due to the oscillating movement, the needle-shaped rollers made of ceramics caused severe step wear at the portion corresponding to the roller end face of the piston pin, and as in the above case, the bearing life was quickly shortened. The present invention has been made in view of such circumstances, and has as its object to prevent step wear of a piston pin and achieve stable high-speed rotation operation.

[0006]

SUMMARY OF THE INVENTION In order to achieve the object, the present invention provides a needle roller bearing device for a connecting rod small end having a small end of a connecting rod as an outer ring and a piston pin as an inner ring. The following configuration is adopted.

[0007] The present invention of the connecting rod small end needle-roller bearing device is composed of a plurality of substantially cylindrical needle rollers, needle rollers and cage that Soo coercive and the needle roller is It is characterized by being formed of ceramics mainly composed of silicon nitride, and having both ends of the needle roller in the axial direction crowned.

The retainer may be formed of a synthetic resin having heat resistance, or the piston pin may be formed of ceramic.

[0009]

[Function] Needle rollers formed of ceramics are superior to ordinary metal needle rollers in terms of high hardness, light weight, and heat resistance. As a result, the PV value is reduced, the temperature rise between the small end of the connecting rod where the needle roller is rolled and the piston pin is suppressed, and various damages of the needle roller are less likely to occur for a longer time than before. Is advantageous. Since the axial ends of the needle roller are crowned, local concentration of contact stress on the piston pin is suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present invention. In the figure, 1 is a connecting rod, 2 is a piston, 3 is a piston pin, and 4 is a needle roller bearing.

Needle roller bearing 4 is connected rod 1
A plurality of ceramic needle rollers 6 and a plurality of ceramic needle rollers 6.
And a so-called cage-and-roller without inner and outer races, comprising a heat-resistant plastic cage 7 guided by the inner peripheral surface of the small end portion 5 of the connecting rod 1.

The needle rollers 6 are made of ceramics made of a sintered body mainly composed of silicon nitride, and have both ends in the axial direction formed with the shape of both ends in the axial direction of full crowning over the entire length in the axial direction. Is formed, and an intermediate portion of the needle roller 6 is formed flat. Such a partial crowning 8 is formed as follows using a super polishing apparatus as shown in FIG. That is, first, the needle roller 6 is placed on the central valley portion of the corrugated portion of the pair of rollers 20 having the shape shown in FIG. By rotating the pair of rollers 20 in a state where is pressed, full crowning is formed on the peripheral surface of the needle roller 6. The needle roller 6 on which the full crowning is formed is moved to a flat portion on the pair of rollers 20, 20, and a grinding stone 22 having a flat tip with respect to the needle roller 6.
By rotating the pair of rollers 20, 20 while pressing the roller, the central portion of the needle roller 6 is polished flat. As a result, the partial crowning 8 remains at both axial ends of the needle roller 6.

The cage 7 has needle pockets 6 in its pockets 9.
Is rotatably held in a state in which it can be freely pulled out in and out of the radial direction. For example, PPS (polyphenylene sulfide), 46 nylon, aromatic polyamide,
Aromatic polyimide, aromatic polyamideimide, PEEK
(Polyetheretheretherketone) and other selected heat-resistant plastics. In order to handle the needle roller 6 while holding it in the retainer 7, Japanese Utility Model Application No. 2-100386 and Japanese Utility Model Application No. 2-1
For example, a fall prevention device described in No. 00387 is used.

In the needle roller bearing 4 of the present embodiment, the hardness of the ceramic needle roller 6 is much higher than that of the metal needle roller 6, and the weight of the needle roller is about 1/2 or less of that of the metal needle roller. And is excellent in heat resistance. Needle roller 6
PV weight (P = bearing average pressure kgf /
cm ² , V = peripheral velocity m / s) can be reduced.
However, because of its high hardness, load-bearing performance can be improved. In addition, since the partial crowning 8 is formed at both ends of the needle roller 6 in the axial direction, edge load can be suppressed. That is, simply using the ceramic needle roller 6 causes the roller pin end corresponding portion of the piston pin 3 to wear stepwise due to the edge load, causing early seizure. For this reason, a partial crowning 8 is applied to both end portions of the needle roller 6 in the axial direction.

Since the cage 7 is made of synthetic resin in addition to the needle roller 6 made of ceramics, the total weight of the needle roller bearing can be reduced. For example, a conventional metal needle roller bearing weighs about 18 g, while that of the present embodiment weighs about 5 g. In addition to this, in the present embodiment, the piston pin 3 is also made of a ceramic made of a sintered body mainly composed of silicon nitride, thereby reducing the weight, increasing the rigidity and preventing step wear. It is aimed at. Therefore, the weight reduction at the small end portion 5 side of the connecting rod 1, that is, at the upper end side of the reciprocating motion is achieved, so that the operation in the high-speed rotation region can be stably performed. Furthermore, when the ceramic needle roller 6 of this embodiment is employed, it can sufficiently withstand use in a region where peeling occurs when a metal needle roller is used. Therefore, even when used under severe conditions in which the amount of lubricating oil in the air-fuel mixture is low, such as a connecting rod support portion of a two-stroke engine, the needle rollers 6 can be used as compared with the conventional case using metal needle rollers. As a result, it is possible to extend the seizure life.

[0017]

[Effect of the Invention] As described above, in the present invention, high hardness, high heat resistance and light weight are realized by using ceramic needle rollers, and both ends of the needle rollers in the axial direction are realized. Because of the partial crowning, it is possible to prevent the needle roller and the piston pin from causing various damages over a longer period of time than with a general metal needle roller, It is possible to suppress an edge load with a contact partner. Therefore, even if it is not a rotary motion like the small end of the connecting rod ,
Oscillating movement is the main component, and during the engine explosion process
Severe operating conditions such as momentary impact of
Under operating conditions where the lubricating oil is diluted ,
It can operate stably for a long time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a connecting rod support structure according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view schematically showing a needle roller bearing.

FIG. 3 is a schematic structural view of a super-polishing apparatus used for peripheral surface treatment of needle rollers.

FIG. 4 is a side view showing a grindstone and rollers of the super polishing apparatus of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connecting rod 2 Piston 3 Piston pin 4 Needle roller bearing device 6 Needle roller 7 Cage 8 Partial crowning

Continuation of the front page (56) References JP-A-55-126115 (JP, A) JP-A-64-55412 (JP, A)

Claims (3)

(57) [Scope of request for utility model registration] 1. A needle roller bearing device for a connecting rod small end having a small end portion of an connecting rod as an outer race and a piston pin as an inner race, comprising a plurality of substantially cylindrical needle rollers and a needle roller. consists of a coercive Soo that retainer and the needle roller is was formed with a ceramic mainly composed of silicon nitride, crowning in the axial direction end portion of the needle-shaped roller is applied, it Needle roller bearing device for a connecting rod small end . 2. A needle roller bearing apparatus for a connecting rod small end according to claim 1, wherein the retainer is formed of a synthetic resin having heat resistance, the needle connecting rod eye, characterized in that Roller bearing device. 3. A needle roller bearing apparatus for a connecting rod small end according to claim 1, wherein the piston pin is formed of ceramics, it connecting rod small end for needle roller bearing apparatus according to claim.