JPH0732881Y2 - Rocker arm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a rocker arm used for an OHC valve operating mechanism of an engine, specifically a roller rocker arm provided with a roller.

(Prior Art) A roller rocker arm that reduces a friction loss by providing a roller at an end contacting a cam is already known. Most of the rocker arm bodies of the conventional roller rocker arm are steel forged products or cast products.
At one end of the rocker arm main body, a cam follower roller that is brought into contact with a driving cam by a roller support shaft to roll is provided.

By the way, it is desirable that the movable portion of the valve mechanism be as light as possible. Therefore, it is conceivable that the rocker arm body is made of aluminum alloy die casting. Since the cam follower roller contacts the cam, it is necessary to form the cam follower roller with a material having a hardness much higher than that of the rocker arm body.

(Problems to be solved by the invention) Therefore, there is a problem that the facing surfaces of the cam follower roller and the rocker arm body are scraped by being scraped by the end surface of the cam follower roller. Further, it is conceivable to rotatably support the cam follower roller on the rocker arm via the needle belling, but there is a fear that the needle bearing may fly out in the axial direction and damage the rocker arm body.

(Means for Solving the Problems) The present invention is intended to provide a rocker arm that solves the above problems, and is pivotally supported by a rocker shaft so that the rocker arm is swingably supported at one end and at a cam facing end and the other end. A rocker arm body made of an aluminum alloy having a valve facing end, a pair of roller supporting arms in which the cam facing end portion of the rocker arm body is formed into a bifurcated shape, and a fitting hole formed in the roller supporting arm. It is arranged between a roller support shaft that is press-fitted and fixed between the support arms, and a cam follower roller that is rotatably supported by the roller support shaft and that abuts on a driving cam and rolls. A needle bearing, a sliding contact plane of each of the roller support arms facing the end surface of the cam follower roller and the needle bearing, and the roller support. A lubricating alumite treatment is applied to the fitting hole into which the holding shaft is fitted, and a quenching treatment is applied to the entire length of the roller support shaft.

(Operation) The cam facing end of the rocker arm main body made of aluminum alloy is formed as a bifurcated roller support arm, and the hardened roller support shaft is press-fitted into the fitting hole of the roller support arm. Since the cam follower roller is supported by the roller support shaft via the needle bearing, the sliding resistance of the cam follower roller is reduced, and the friction of the sliding contact surface of the roller support shaft with the needle bearing is reduced. In addition, since the sliding abutment surface facing the end surfaces of the cam follower roller and the needle bearing of the roller support arm is subjected to lubricating alumite treatment, the friction resistance between the end surface of the cam follower roller and the needle bearing is reduced,
Further, since the fitting hole into which the roller support shaft is inserted is subjected to the lubricating alumite treatment, the work of press-fitting the roller support shaft into the fitting hole becomes easy.

(Structure) Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings.

First, referring to FIG. 1, the outline of a rocker arm having rollers will be described. The rocker arm 1 is swingably supported by a rocker shaft 2. Rocker arm 1
Comprises a rocker arm body 3 of an aluminum alloy die cast, an adjusting screw 4 provided at one end 3a thereof, and a cam follower roller 5 rotatably provided at the other end thereof. Cam follower roller (hereinafter simply “roller”)
5) is brought into contact with a driving cam 7 fixed to a cam shaft 6. The adjusting screw 4 is fixed by a lock nut 8 after the adjustment, and the lower end portion of the adjusting screw 4 is brought into contact with the upper end portion of the valve stem 9.

Next, the shape of the rocker arm body 3 will be described with reference to FIGS. 1 and 2. The rocker arm body 3 is formed with a swing center hole 3b inserted through the rocker shaft 2, an internal thread portion 10 as an adjuster mounting portion, and a pair of roller support arms 12 and 13 facing each other with a recess 11 therebetween. ing. A fitting hole into which a hollow roller support shaft 14 that rotatably supports the roller 5 is press-fitted into the roller support arms 12 and 13.
12a and 13a are formed respectively. The roller 5 is made of steel, preferably ceramic, and has a fourth
As shown in the figure, a rotation center hole 5a into which the roller support shaft 14 is fitted and inserted through a needle bearing 16 is formed. The roller support shaft 14 is made of a material having a hardness higher than the hardness of the aluminum alloy forming the rocker arm body 3, and has a hole 14a for oil supply formed substantially in the longitudinal center thereof. The roller support shaft 14 is hardened over its entire length.

Inner side surfaces of the pair of roller supporting arms 12 and 13, that is, side surfaces facing both end surfaces of the roller 5 (see FIG. 4) 12b and 13b.
Is subjected to a lubricating alumite treatment for hardening the surface. This process is performed on the side surfaces 12b and 13b as sliding contact planes.
Is applied to the entire surface of. Although the illustrated embodiment shows the adjusting screw as the lash adjuster, an auto lash adjuster may be mounted.

FIG. 3 shows a press-fitting process in which the roller 5 having a needle bearing (not shown) is assembled between the pair of roller supporting arms 12 and 13. Here, the roller 5 is the center hole of its rotation.
A needle bearing (not shown) is arranged in advance on 5a, and the temporary bearing 15 is used to prevent the needle bearing from falling off, and then fitted into the recess 11.
Then, the roller support shaft 14 applied to the fitting hole 12a of the one roller support arm 12 is pressed in the direction of the arrow by a pressing means (not shown) to press-fit the support shaft 14 into the fitting holes 12a, 13a. . Further, the temporary shaft 15 is pushed out as the roller support shaft is press-fitted. Then, as shown in FIG. 4, the roller support shaft 14
The press-fitting is stopped when the end surface 14b is inserted to a position where it is flush with the outer surface 13c of the roller support arm 14.

When the needle bearing 16 is used as described above, the side surface of the arm facing both ends of the needle bearing 16 is also subjected to the lubricating alumite treatment. Further, when the roller support shaft 14 is press-fitted, in order to prevent the tip portion 14b of the shaft from rubbing the inner surfaces of the fitting holes 12a, 13a of each arm, a lubricating alumite treatment is also applied to the inner peripheral surfaces of these fitting holes. Give.

Then, when the rocker arm is attached to the engine and rocked, the roller 5 is rotated according to the cam 7. The end surface of the rotating roller 5 has roller support arms 12, 13
Lubricate the inner surface, which has been lubricated and anodized. Further, although the phenomenon that the needle bearing is often extended in the axial direction often occurs, the protruding end portion of the needle bearing 16 also rubs the lubricated alumite treated inner side surfaces 12b, 13b.

(Effect of the Invention) As described above, according to the rocker arm of the present invention,
The rocker arm body can be made lighter by making it from an aluminum alloy.In particular, the roller support shaft that is press-fitted into the fitting hole of the bifurcated roller support arm is subjected to quenching treatment, and this roller support shaft is inserted through a needle bearing. Supports the cam follower roller. Therefore, abrasion of the sliding contact surface of the roller support shaft with the needle bearing is prevented in advance, and the sliding resistance can be reduced permanently.

In particular, the sliding surface of the roller support arm facing the cam follower roller and the needle bearing is lubricated by alumite treatment, and the fitting hole into which the roller support shaft is inserted is also lubricated by alumite treatment. Wear and frictional resistance of the sliding contact surface due to the end surface of the bearing can be reduced, and when the roller support shaft is press-fitted into the fitting hole, the inner peripheral surface of the fitting hole is hardened so that galling is prevented and smooth press-fitting is possible. The workability is improved and the roller support shaft can be accurately fixed to a predetermined position of the support arm.

[Brief description of drawings]

FIG. 1 is a schematic front view of a valve mechanism showing an example of a rocker arm equipped with rollers, and FIG. 2 is an exploded perspective view schematically showing a needle bearing of an embodiment of the rocker arm of the present invention.
FIG. 3 is a cross-sectional view of essential parts showing a needle bearing in a press-fitting process of a roller support shaft of a rocker arm, and FIG.
It is a principal part sectional view of the rocker arm of the figure. 3 ... rocker arm body, 5 ... cam follower roller,
12,13 …… Roller support arm, 14 …… Roller support shaft, 12
a, 13a …… Mating hole, 12b, 13b …… Side surface as sliding contact plane, 1
6 …… Needle bearing.

Continuation of the front page (56) Reference JP-A-59-162310 (JP, A) Actually opened 61-21804 (JP, U) Actually opened 61-6609 (JP, U) Actually opened 59-117812 (JP , U) Jikkou 41-22324 (JP, Y1)

Claims (1)

[Scope of utility model registration request] 1. A rocker arm body made of an aluminum alloy, which is swingably pivotally supported by a rocker shaft and has a cam facing end at one end and a valve facing end at the other end, and the cam facing in the rocker arm body. A pair of roller supporting arms whose end portions are formed in a bifurcated shape, a roller supporting shaft press-fitted into a fitting hole formed in the roller supporting arm and fixed between the supporting arms, and the roller supporting shaft. A cam follower roller which is rotatably supported and which is arranged between the cam follower roller and the drive cam so as to roll, and the cam follower roller and the needle bearing of each roller support arm. The sliding contact surface facing the end face of the roller support shaft and the fitting hole into which the roller support shaft is fitted are subjected to lubricating alumite treatment, and the entire roller support shaft is Rocker arm, characterized in that subjected to quenching treatment over.