JP2581973Y2 - Cam follower - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam follower used for a valve train of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine of an overhead camshaft type or the like, a cam follower such as a rocker arm having a roller that comes into rolling contact with a cam is used for a valve train. As a material for the roller of the rocker arm, bearing steel such as SUJ2 is generally used. After so-called quenching of the bearing steel, the steel is tempered and adjusted so that the hardness of the rolling surface becomes HRC 60 to 62. ing.

[0003]

The roller of the rocker arm is a portion that directly contacts the cam, which is strictly lubricated among the components constituting the internal combustion engine, and is located in the boundary lubrication region. Under such severe lubrication conditions, the roller and the cam basically come into rolling contact with each other, but, for example, at a timing when the applied load from the cam fluctuates rapidly, a slight slippage occurs between the two. For this reason, there has been a problem that the rolling surface of the roller is worn, and sufficient durability cannot be secured.

[0004] The present invention has been made in view of the above problems, and provides a rocker arm that can suppress the abrasion of the rolling surface of the roller and exhibit excellent durability. With the goal.

[0005]

According to the present invention, there is provided a cam follower which is used in a valve train of an internal combustion engine and includes a roller made of JIS standard bearing steel which is in rolling contact with a cam. carbonitriding to the roller
Subjected to heat treatment with a reduction in the rolling surface of the roller
Form carbon / nitride, 0.1m from the outermost surface of this surface
Set the hardness at a depth of m to a value of HRC 63 or more
This reduces wear on the roller surface due to friction with the cam.
It is characterized in that it is reduced .

[0006]

According to the cam follower having the above structure, the JIS regulations
Roller made of high grade bearing steel is heat treated with carbonitriding.
By doing so , carbon / nitride
To a depth of 0.1 mm from the outermost surface of this surface.
Is set to a value of HRC 63 or higher ,
Excellent abrasion resistance can be secured, and friction with the cam
Abrasion of the roller surface due to the above can be reduced.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a schematic view showing a main part of a valve train of an internal combustion engine equipped with a rocker arm 1 as a cam follower of the present invention. The rocker arm 1 is provided with a rotatable roller 2 substantially at the center thereof.
Is pressed in rolling contact with the cam 3 to swing up and down about the base end 1a to which the pivot shaft 5 is attached, and the valve stem 4
Press.

In the rocker arm 1, the roller 2
It is constituted by bearing steel of JIS standard such as SUJ2, at least the rolling surface part, carbonitriding treatment
Has been subjected, the hardness of the rolling surface portion, at a depth of at least 0.1mm good wear resistance ensure all Ku outermost surface, Ru der than HRC63.

[0009] The roller 2 is subjected <br/> carbonitrided processing the surface portion, after the quenching and simultaneously forming a carbonitride compound to the surface portion, the normal tempering temperature (150 ℃ ~200 ℃)
It can be obtained by tempering at a higher temperature (200 ° C. to 250 ° C.). For example, when SUJ2 is used as the bearing steel, carbonitriding treatment is performed at about 870 ° C. for several hours, followed by quenching, and then tempering at about 210 ° C.
HRC62 in a depth range of 0.20 mm from the outermost surface
Can be obtained (see FIG. 2).

[0010] Incidentally, more to the carbonitriding treatment, since the carbon-nitride in the surface portion is formed, after conducting the above high-temperature tempering can also be allowed to remain an appropriate amount of austenite on the surface portion As a result, a good rolling fatigue life can be secured. Further, after the carburizing nitriding, if Hodokose the sub-zero treatment can be in the normal tempering temperature is obtained similar to the above roller 2.

FIG. 3 shows the roller 2 of the embodiment shown in FIG.
And after normal quenching the same bearing steel, about 180 ℃
5 shows the results of measuring the amount of wear of each roller after operating the roller (comparative example) obtained by tempering under the same conditions for the same time. As is clear from this drawing, the wear amount of the roller using the roller of the example is much smaller than that of the roller using the roller of the comparative example.

[0012]

[Effects of the Invention] As described above, according to the cam follower of the invention, the roller made of JIS standard bearing steel is carburized.
Rolling of the roller by heat treatment with
Form carbon / nitride on the surface, and from the outermost surface of this surface
Hardness at a depth of 0.1mm to a value of HRC63 or higher
Setting ensures excellent wear resistance.
Greatly reduces wear on the roller surface due to friction with the cam.
Can be For this reason, it has a unique practical effect that excellent durability can be exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a main part of a valve train equipped with a rocker arm of the present invention.

FIG. 2 is a graph showing a hardness distribution near a rolling surface portion of a roller.

FIG. 3 is a graph showing measurement results of the amount of wear in Examples and Comparative Examples.

[Explanation of symbols]

 1 rocker arm 2 roller 3 cam

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F01L 1/00-1/46 F16C 33/34 F16H 53/06

Claims (1)

(57) [Scope of request for utility model registration] [Claim 1] used in the valve train of an internal combustion engine, in the cam follower with a JIS standard bearing steel roller in rolling contact with the cam, heat treated with carbonitriding into the roller rolling surface of the roller Forming charcoal / nitride
And at a depth of 0.1 mm from the outermost surface of this surface portion.
By setting the hardness to a value of HRC 63 or more,
A cam follower characterized by reducing abrasion of a roller surface due to friction with the cam follower.