JP2636218B2 - Rocker arm and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm used for an OHC valve mechanism of an engine, and more particularly to a roller rocker arm having rollers and a method of manufacturing the same.

(Prior Art) A roller rocker arm that reduces 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 arms are forged or cast products made of steel. The roller is supported by a hardened support shaft that is press-fitted into the rocker arm main body, crimped and fixed. This support shaft is hardened only at the center portion in order to caulk and deform both end portions. Also,
At one end of the rocker arm is provided an adjuster that contacts the valve stem.

(Problems to be Solved by the Invention) When the support shaft for rotatably supporting the roller is fixed by caulking, there is a problem that the parallelism between the rotation center axis of the roller support shaft and the rotation center axis of the rocker arm is deviated. is there. Further, when the roller support shaft is pressed into the rocker arm main body, there is another problem that abrasion damage occurs on the surface of the support shaft and hinders the rotation of the roller. In addition, the quenching of the support shaft is partial, which increases the cost of the shaft.

Further, in a rocker arm having a roller, a concave portion into which the roller is fitted and an adjuster mounting portion into which the adjuster is fitted are provided. When the rocker arm is cast, in addition to the upper and lower dies, the concave portion is used. And a plurality of movable dies for forming the mounting portion must be prepared and moved in different directions, and the molding cost is high. Further, it is desirable that the movable portion of the valve train is as light as possible.

(Means for Solving the Problems) The present invention provides a rocker arm body made of an aluminum alloy and integrally having a pair of roller support arms, and a material harder than the rocker arm body hardened over its entire length, The roller support arm has a chamfered portion over the entire outer peripheral surface thereof, and is press-fitted and fixed from a fitting hole provided on one of the roller support arms to a fitting hole provided on the other of the roller support arms. And a cam follower roller rotatably supported by the roller support shaft and abutting against a driving cam. The roller support shaft has the chamfered portion at one end thereof, The other roller support arm is press-fitted so as not to be exposed to the outer surface, and the chamfered portion on the other end is formed around the fitting hole of the one roller support arm. The rocker arm is fixed to the roller support arm by caulking the roller support arm side of the roller support arm, and a concave portion and a lash adjuster into which the roller is fitted when the rocker arm of aluminum alloy die casting is formed are mounted. Wherein the moving directions of the movable dies forming the mounting portions are the same.

According to the first aspect of the invention, since the roller supporting shaft is quenched with a material having a higher hardness than the rocker arm main body over its entire length, the outer peripheral surface serving as the sliding surface of the roller when the roller supporting shaft is press-fitted. Scratch is not caused, and the quenching process becomes easier compared to masking, partial quenching, and the like in the case of performing a conventional partial quenching process. The roller support shaft has chamfers at both ends thereof, and the chamfer at one end of the roller support shaft is press-fitted so as not to be exposed on the other outer surface of the roller support arm. The side chamfering portion caulks the roller support arm side around one fitting hole of the roller support arm to the chamfered portion, so that the chamfered portions on one end side and the other end side of the roller support shaft are formed. The roller support arm functions as a stopper in the axial direction, and the roller support shaft itself is not caulked and fixed, so that an impact load does not act in the axial direction. In addition, since the rocker arm main body is made of an aluminum alloy and the rocker arm main body side is caulked and fixed, the load for caulking is low, the size of equipment for caulking can be reduced, and the weight of the valve mechanism can be reduced.

According to the second aspect, the first mold and the second mold divided by a plane that is orthogonal to the rotation center axis of the rocker arm and that passes through the recess into which the cam follower roller is fitted are combined with each other, and a space corresponding to the recess is further provided. And a fourth mold forming a space corresponding to the adjuster mounting portion in a plane orthogonal to the rotation center axis of the rocker arm.
After inserting the aluminum alloy melt into the space formed by the second mold and the second mold, the first mold and / or the second mold are opposed to each other along the rotation center axis of the rocker arm. The third mold and the fourth mold are removed in the same direction by moving the third mold and the fourth mold in the same direction.
Since the moving directions of the molds are the same, the apparatus for moving the molds can be shared.

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

First, an outline of a rocker arm having rollers in FIG. 1 will be described. The rocker arm 1 is slidably supported on a rocker shaft 2. Rocker arm 1
Is an aluminum alloy die-cast rocker arm body 3,
It comprises an adjuster screw 4 provided at one end 3a and a cam follower roller 5 rotatably provided at the other end. A cam follower roller (hereinafter simply referred to as a “roller”) 5 is brought into contact with a driving cam 7 fixed to a cam shaft 6. Adjustable screw 4
Is fixed by a lock nut 8 after adjustment, and a lower end thereof is brought into contact with an upper end of the valve stem S.

Next, the shape of the rocker arm body 3 will be described with reference to FIGS. The rocker arm body 3 is formed with a swing center hole 3b inserted into the rocker shaft 2, an internal thread 9 as an adjuster mounting portion, and a pair of roller support arms 11 and 12 facing each other with a recess 10 therebetween. ing. The roller support arms 11 and 12 are formed with fitting holes 11a and 12a into which a hollow roller support shaft 13 for rotatably supporting the roller 5 is press-fitted. The roller 5 is formed of steel, preferably ceramic, and has a rotation center hole 5a slightly larger than the roller support shaft 13 at the center thereof. The roller support shaft 13 is formed of a material having a hardness higher than the hardness of the aluminum alloy constituting the rocker arm body 3, and has an oil supply hole 13a formed at a substantially central portion in the longitudinal direction. Also, the roller support shaft 13
Has been quenched over its entire length.
As shown in FIG. 5 and FIG. 5, a chamfered portion 13c is provided over the entire outer circumference of the one end side, and a chamfered portion 13d is provided over the entire circumference of the outer circumference of the other end.

Next, a method of manufacturing the rocker arm body 3 will be described with reference to FIG. The rocker arm body 3 is vertically divided in a plane (indicated by a dashed line) perpendicular to the rotation center axis (oscillation center hole 3b) and passing through the concave portion 10 and includes a lower portion including the roller support arm 11. A first mold (not shown) for molding the half 3A, a second mold (not shown) for molding the upper half 3B including the roller support arm 12, and a space 10 corresponding to the recess 10;
The third die 14 for forming A and the fourth die 15 for forming the space 9A corresponding to the adjuster mounting portion 9 are formed by pouring the molten aluminum alloy into the gap formed by pressurizing. . Although the first mold and the second mold are well-known and not shown, it is needless to say that a projection for forming the swing center hole 3b and the fitting holes 11a and 12a is provided. One of the first mold and the second mold, for example, the second mold is movable in a direction away from the other first mold along the rotation center axis of the roller rocker arm. The third die 14 and the fourth die 15 are movable dies, and are extracted in the directions of the arrows a and b after the rocker arm main body 3 is formed. The directions indicated by the arrows a and b are parallel to each other on a plane orthogonal to the swing center axis of the rocker arm body 3. In other words, the third mold 14 and the fourth mold 15 are provided movably in the same direction. Then, after assembling each of the above-described molds to form a space corresponding to the rocker arm main body 3 and press-fitting the aluminum alloy melt, the second mold is separated from the first mold along the rotation center axis of the rocker arm, The third mold 14 and the fourth mold 15 are extracted in the directions of arrows a and b, which are the same direction. That is, when removing the mold, the movable mold only needs to be moved in two directions.

The rocker arm body (3) after the die is formed with an adjuster mounting portion 9A before processing and a concave portion (10) before processing. The adjuster mounting portion 9A is machined into the female screw portion 9 by a screw cutting device, and the concave portion 10 is provided with the roller support arms 11,12.
The opposing surfaces 11b and 12b are preferably cut and polished. The swing center hole 3b and the fitting holes 11a and 12a may also be cut. Regardless of whether or not processing is performed, the diameters of the fitting holes 11a and 12a before press-fitting the roller support shaft 13 are set to be slightly smaller than the diameter of the roller support shaft 13. In the illustrated embodiment, an adjuster screw is shown as a lash adjuster.However, in a rocker arm of a type to which an auto lash adjuster is mounted, after a hole having a size larger than the adjuster mounting portion 9A and having a ceiling is formed, a cutting finish is performed. And an oil passage (not shown) is formed between the oil passage and the swing center hole 3b.

The roller 5 is mounted on the rocker arm body 3 that has been cut as described below. In FIG.
The roller 5 fitted in 10 is supported by the roller support arms 11 and 12 by a temporary shaft 16. The roller support shaft 13 applied to the fitting hole 11a of one roller support arm 11 is pressed in the direction indicated by an arrow by a pressing means (not shown) to
Into the fitting holes 11a and 12a. At this time, the fitting holes 11a, 12a
Is slightly expanded. Further, the temporary shaft 16 is pushed out as the roller support shaft is pressed. Then, as shown in FIG. 5, the end surface 13b of the roller support shaft 13 is
The press-fitting is stopped when it is inserted to a position where it becomes flush with the outer side surface 12c. Roller support shaft 1 pressed into fitting hole 11A
3, the other end side chamfered portion 13d is swaged by the roller support arm 11, as shown in FIG.

In the embodiment shown in FIG. 5, the roller 5 is directly fitted on the roller support shaft 13, but a needle bearing 17 may be interposed between them as shown in FIG.

(Effects of the Invention) As described above, according to the rocker arm of the present invention, since the rocker arm main body is made of die-cast aluminum alloy, the movable portion of the valve train can be greatly reduced in weight. Besides, not only the material of the rocker arm body was simply changed,
Since the roller support shaft for supporting the roller is fixed by press-fitting, there is no disturbance in the parallelism between the support shaft and the rocker shaft due to the caulking of the support shaft. Further, since the partner to which the roller support shaft is press-fitted is an aluminum alloy, there is no abrasion damage on the roller support shaft surface during press-fitting. Furthermore, just by caulking one end of the roller support shaft, the roller support shaft can be firmly fixed to the roller support arm,
The roller support shaft does not shift in the axial direction. Also, since the roller support shaft is quenched along its entire length, the quenching process becomes easier as compared with masking, partial quenching, and the like when performing a partial quenching process.

Further, according to the method of manufacturing the rocker arm of the present invention, since the moving directions of the third mold and the fourth mold are the same, the molding cost of the rocker arm can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a valve operating mechanism showing an example of a rocker arm provided with rollers, FIG. 2 is an exploded perspective view of the rocker arm showing one embodiment of the present invention, and FIG. 3 is a method for manufacturing a rocker arm of the present invention. FIG. 4 is a cross-sectional view showing the process of press-fitting the roller support shaft, FIG. 5 is a cross-sectional view showing the state after the press-fit of the roller support shaft, and FIG. 6 is another view of the present invention. It is sectional drawing which shows an Example. 3 ... rocker arm body, 4 ... adjuster, 5 ... cam follower roller, 11, 12 ... roller support arm, 13 ...
... roller support shaft, 14 ... third mold, 15 ... fourth mold,

Continuation of the front page (56) References Practical application Microfilm (JP, U) Principal application Sho59-165770 (JP, U) Microfilm (JP, U) which photographed the contents of the specification and drawings attached to the application for Japanese Patent Application No. 162421

Claims (2)

(57) [Claims] 1. A rocker arm body made of an aluminum alloy and integrally having a pair of roller support arms, and a material harder than the rocker arm body is quenched over its entire length, and the entire outer peripheral surfaces of both ends thereof are provided. A roller support shaft having a chamfered portion over the circumference and press-fitted and fixed in a direction from a fitting hole provided on one of the roller supporting arms to a fitting hole provided on the other of the roller supporting arms; A cam follower roller rotatably supported by a roller support shaft and abutting against a driving cam, and the roller support shaft is configured such that the chamfered portion at one end thereof is outside the other roller support arm. The beveled portion on the other end side is press-fitted so as not to be exposed to the side surface, and the roller support arm side around the fitting hole of the one roller support arm faces the face. Portion by caulking to Ri, rocker arm, characterized in that fixed to the roller supporting arm. 2. A concave portion comprising a pair of roller support arms into which a cam follower roller which rolls in contact with a driving cam is fitted at one end, and an adjuster mounting portion to which an adjuster which comes into contact with a valve stem is mounted at the other end. A method for manufacturing an aluminum alloy die-casting rocker arm having
A third part, which is divided by a plane perpendicular to the rotation center axis of the rocker arm and passing through the concave part, forms a space corresponding to the concave part by combining the first die and the second die forming the rocker arm body. And a fourth die forming a space corresponding to the adjuster mounting portion are inserted into a space formed by the first die and the second die in a plane perpendicular to the rotation center axis of the rocker arm. Then, after the aluminum alloy melt is pressed into the space formed by each of the molds and molded, the first
And / or one of the molds is moved in opposite directions along the center axis of rotation of the rocker arm.
A method for manufacturing a rocker arm, comprising: moving the first mold and the fourth mold in the same direction and removing the mold.