JP3689072B2 - Manufacturing method of rocker arm body - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method of manufacturing a main body of a rocker arm that opens and closes a valve provided in a cylinder head in response to a sliding operation by a cam.
[0002]
[Prior art]
An example of this type of rocker arm is shown in FIGS. In the figure, 1 is a cam portion of a camshaft, 2 is a valve stem portion, 3 is a pivot portion of a lash adjuster, and 4 is a rocker arm.
[0003]
The rocker arm 4 has a structure in which a roller 6 is rotatably attached to a rocker arm body 5. The rocker arm main body 5 is manufactured by sheet-metal-metal plate in a substantially U shape when viewed from the side, and includes a pair of roller support wall portions 7 and 8 facing each other substantially in parallel, 8 and a connecting portion 10 having a rectangular through hole 9 in the middle in the longitudinal direction. One end side in the longitudinal direction of the connecting portion 10 is drawn into a substantially U-shaped cross section, thereby forming an inverted concave valve engaging portion 11. Similarly, a substantially hemispherical pivot engaging portion 12 is also formed on the other end in the longitudinal direction of the connecting portion 10 by drawing.
[0004]
The roller 6 is supported between the pair of roller support walls 7 and 8 of the rocker arm body 5 via the shaft 13 so that the roller 6 protrudes slightly from the through hole 9. The roller 6 is in contact with the cam portion 1, the valve engaging portion 11 is engaged with the valve stem portion 2, and the pivot engaging portion 12 is engaged with the pivot portion 3 of the lash adjuster.
[0005]
[Problems to be solved by the invention]
By the way, the rocker arm 4 is configured such that the valve engaging portion 11 side is swung up and down with the pivot engaging portion 12 as a fulcrum as the cam portion 1 rotates. Should be as light as possible.
[0006]
In consideration of such a demand, conventionally, the width of the rocker arm body 5, that is, the distance between the pair of roller support wall portions 7 and 8 is designed to be as narrow as possible. In such a design, the peripheral edge portion of the pivot engaging portion 12 tends to be close to the outer surface of the corresponding portion of the roller support wall portions 7 and 8 in the connecting portion 10, and therefore the pivot engaging portion 12 is formed. When heat treatment is performed later, distortion occurs at different degrees in the width direction (X direction in FIG. 9) and the longitudinal direction (Y direction in FIG. 9) of the pivot engaging portion 12, and as a result, the pivot engaging portion 12. May be oval. When the pivot engaging portion 12 becomes elliptical in this way, the contact area pressure is locally reduced because the pivot portion 3 of the lash adjuster comes into contact with the inner surface of the pivot engaging portion 12 and the contact area becomes small. In addition to causing local wear, the contact position between the pivot engaging portion 12 and the pivot portion 3 of the lash adjuster is shifted according to the tilt angle of the rocker arm 4 that swings. The movement of the valve may fluctuate, and the opening and closing timing of the valve may go wrong.
[0007]
The present invention was devised in view of such circumstances, and provides a method for manufacturing a rocker arm main body in which an inner surface shape of a pivot engaging portion can be formed with high accuracy.
[0008]
[Means for Solving the Problems]
According to the present invention, a connecting portion that spans between both walls on one end side in the longitudinal direction of a pair of roller support wall portions provided so as to extend substantially parallel to each other is used as a valve engaging portion. A method for manufacturing a rocker arm body in a rocker arm having a rocker arm body having a connecting portion spanned between walls as a pivot engaging portion, and a roller rotatably mounted between the roller support wall portions. The metal plate for punching the rocker arm body and the punched metal plate for the rocker arm body are provided so as to extend substantially parallel to each other , and at the position of the connecting portion of the pivot engaging portion. as the lateral portion forms a connecting portion to the pair of roller supporting walls and the longitudinal end portion including a projecting portion which is flared outwardly, and the folding process in substantially U-shape viewed from the side, the The center of the connecting portion of the bot engaging portion, the rollers support walls extending in the cylindrical against the cylindrical receiving mold from side receiving mold contact portion of the overhang of both rollers supporting walls of as the flat portion between the parts and the pivot engaging portion, a step of substantially draw forming a pivot engagement portion of the hemispherical so as to protrude toward the extension side and the same direction of the rollers support wall portion, the rocker arm main body Heat-treating.
[0009]
[Action]
According to the manufacturing method of the present invention, in the connecting portion where the pivot engaging portion is formed, there is a flat portion around the entire pivot engaging portion. Thus, the inner surface of the pivot engaging portion can be made into a substantially spherical surface.
[0010]
Therefore, the pivot engaging portion and the pivot portion of the lash adjuster are in surface contact and the contact area is increased, so that the contact surface pressure is reduced and wear is suppressed, and the rocker arm swing fulcrum is stationary. Therefore, it becomes possible to manufacture a rocker arm body in which the swinging operation is stable and the valve opening / closing timing is properly maintained.
[0011]
【Example】
1 to 6 show an embodiment of the present invention. In these drawings, the same reference numerals are given to the same components as those in the conventional example. In the figure, 1 is a cam portion of a camshaft, 2 is a valve stem portion, 3 is a pivot portion of a lash adjuster, and 40 is a rocker arm.
[0012]
The rocker arm 40 has a structure in which a roller 42 is rotatably attached to a rocker arm main body 41, and the basic structure is substantially the same as the conventional example. The rocker arm main body 41 is manufactured by sheet-metalizing a single metal plate (a metal plate for a rocker arm main body) in a substantially U shape in a side view, and includes a pair of roller support wall portions 43 facing each other substantially in parallel. 44, a connecting portion 45 that integrally connects each side of one end in the longitudinal direction of both roller support wall portions 43, 44, and one side of the other end in the longitudinal direction of both roller support wall portions 43, 44 by welding. And a separate valve engaging member 46 to be bonded. The coupling portion 45 is formed with a substantially hemispherical pivot engaging portion 47 by drawing so as to protrude in the same direction as the protruding direction of the roller support wall portions 43 and 44.
[0013]
The roller 42 is rotatably supported via a shaft 48 between a pair of roller support wall portions 43 and 44 of the rocker arm main body 41, and both the roller support wall portions 43 and 44, the connecting portion 45, and the valve engagement. It protrudes slightly from a rectangular through hole 49 formed by being surrounded by the member 46.
[0014]
The above-described rocker arm body 41 is formed by punching a single metal plate into a shape as shown in FIG. 6A, and then bending it into a substantially U shape when viewed from the side along the broken line in FIG. The state shown in FIG. After that, as shown in FIG. 6C, a substantially hemispherical pivot engaging portion 47 is formed in the approximate center of the connecting portion 45 by drawing, and as shown in FIG. A separate valve engaging member 46 is attached by welding.
[0015]
The feature of this embodiment is that the periphery of the pivot engaging portion 47 of the rocker arm main body 41 is improved. That is, in the pair of roller support wall portions 43 and 44, projecting portions 50 and 51 that are curved with substantially the same curvature as the outer peripheral curvature of the pivot engaging portion 47 are outwardly provided at the side portions of the pivot engaging portion 47. By providing the overhang portions 50 and 51, flat portions 52 and 52 are provided on both sides of the pivot engaging portion 47. Since such flat portions 52 are provided, the entire circumference of the pivot engaging portion 47 is flat in the connecting portion 45. As shown in FIG. 5, a cylindrical receiving mold 53 for forming the pivot engaging portion 47 is applied to the flat portion of the connecting portion 45, so that the pivot engaging portion 47 is squeezed. When molding, both roller support wall portions 43 and 44 are not plastically deformed, and even if heat treatment of the rocker arm main body 41 is performed thereafter, the degree of distortion generated in the pivot engagement portion 47 is reduced. Since the entire circumference of 47 is substantially constant, the inner surface shape of the pivot engaging portion 47 can be made into a substantially perfect spherical surface shape according to the precision at the time of drawing.
[0016]
In addition, this invention is not limited only to the said Example. For example, the overall shape of the rocker arm main body 41 is arbitrary, and a plurality of needle rollers may not be interposed between the roller 42 and the shaft 48. In addition, the valve engaging member 46 is separated from the rocker arm main body 41, but the one formed integrally with the rocker arm main body 41 is also included in the present invention. Further, as illustrated in FIG. 7, the overhang portions 50 and 51 may be provided so as to be parallel to each other as a straight line.
[0017]
【The invention's effect】
As described above, in the present invention, by providing a flat portion on the entire circumference of the pivot engaging portion, the degree of distortion generated by the heat treatment can be made almost constant on the entire circumference of the pivot engaging portion. The inner surface shape of the pivot engaging portion can be formed in a substantially spherical shape. Therefore, the pivot engaging portion and the pivot portion of the lash adjuster can be brought into surface contact with each other, and the contact area can be increased. Since the swing fulcrum can be fixed, the swing operation can be stabilized and the valve opening / closing timing can be optimized. As described above, the present invention can greatly contribute to improvement of reliability as a product.
[Brief description of the drawings]
1 is an exploded perspective view of an embodiment of the rocker arm of the present invention. FIG. 2 is a plan view of the rocker arm of FIG. 1. FIG. 3 is a cross-sectional view of (3)-(3) in FIG. (4)-(4) Enlarged cross-sectional view [FIG. 5] (5)-(5) Enlarged cross-sectional view of FIG. 2 [FIG. 6] Plan view showing the manufacturing procedure of the rocker arm of FIG. FIG. 8 is an exploded perspective view of a conventional rocker arm. FIG. 9 is a plan view of the rocker arm of FIG. 8. FIG. 10 is a cross-sectional view of (10)-(10) in FIG. 11 is an enlarged cross-sectional view of (11)-(11) in FIG. 9. FIG. 12 is an enlarged cross-sectional view of (12)-(12) in FIG.
DESCRIPTION OF SYMBOLS 1 Cam part 40 Rocker arm 41 Rocker arm main body 42 Roller 43, 44 Roller support wall part 45 Connection part 46 Valve engagement member 47 Pivot engagement part 50, 51 Overhang part 52 Flat part

Claims (1)

A pair of roller support wall portions extending so as to face each other in parallel are connected to each other on both ends on one end in the longitudinal direction, and are connected between both walls on the other end in the longitudinal direction. A method for manufacturing a rocker arm body in a rocker arm having a rocker arm body having a connecting portion to be pivoted as a pivot engaging portion, and a roller rotatably mounted between the two roller support wall portions,
A process of punching out a single metal plate to make a metal plate for the rocker arm body,
A metal plate for the rocker arm body that has been punched out is provided so as to extend substantially parallel to each other , and a projecting portion whose lateral portion projects outward at the position of the connecting portion of the pivot engaging portion is provided. Including a pair of roller support wall portions and a longitudinal end portion so as to form a connecting portion, and a step of bending the substantially U shape in a side view;
A cylindrical receiving mold is applied to the center of the connecting part on the pivot engaging part side from the extending side of the both roller supporting wall parts, and the cylindrical receiving mold contact part is placed on the tension of the both roller supporting wall parts . as the flat portion between the output portion and the pivot engaging portion, a step of substantially draw forming a pivot engagement portion of the hemispherical so as to protrude toward the extension side and the same direction of the rollers supporting walls,
Heat-treating the rocker arm body;
The manufacturing method of the rocker arm main body containing this.

Images