WO2003044332A1

WO2003044332A1 - Rocker arm

Info

Publication number: WO2003044332A1
Application number: PCT/JP2002/012160
Authority: WO
Inventors: Eishi Shibuya
Original assignee: Nsk Ltd.
Priority date: 2001-11-22
Filing date: 2002-11-21
Publication date: 2003-05-30
Also published as: AU2002366031A1

Abstract

A rocker arm comprising an arm main body, a shaft, and a roller, wherein the arm main body has a pair of sidewalls, connecting walls for connecting the pair of sidewalls, an opening passing between the connecting walls, and through-holes in registered positions in the pair of sidewalls. An opening in the arm main body is formed by the deformation of a punched hole when an integral construction of U-shaped cross-section consisting of a pair of sidewalls and a connecting wall is formed by applying draw-forming to a metal sheet having a pre-punched hole relieved at the corners. The shaft is inserted into a pair of through-holes and supported by the pair of sidewalls. The roller is rotatably supported on the shaft.

Description

Description Rocker arm Technical field

The present invention relates to a rocker arm that constitutes a valve train of an internal combustion engine, and more particularly, to a technique for preventing a work from cracking during a drawing process. Background art

In recent years, in order to suppress power loss due to friction with the camshaft and wear of the contact surface, a valve-type rocker arm equipped with a roller that comes into contact with the cam lobe has been adopted for the valve mechanism of the internal combustion engine in recent years. There are many. Conventionally, forged or forged arm bodies have been used for roller-type rocker arms. However, in order to reduce the inertial mass of the valve train and the manufacturing cost, Japanese Patent Laid-Open No. 3-172 As described in Japanese Unexamined Patent Publication No. 506/1996, Japanese Unexamined Patent Publication No. 7-15009, etc., various arm bodies of press-formed products of steel plates have been developed.

The arm body of a steel sheet press-formed product is obtained by punching a steel sheet or the like into a predetermined shape to obtain a blank, and then plastically deforming the blank with a press die to connect a pair of side walls and a connecting wall connecting these side walls. It is manufactured through a process of forming into a substantially U-shaped cross-section consisting of A rectangular opening for exposing the roller on the camshaft side is formed in the arm body.This opening can be formed by punching the blank at the same time as blanking, or by punching the arm body after press forming. It is formed by either. Incidentally, the boss to which the pivot shaft is screwed is formed by a parling process when the arm body is formed, and the through-hole into which the roller shaft is pressed and fitted is generally formed after the arm body is formed. is there.

By the way, the punched hole that becomes the opening after molding is simultaneously punched when punching the plank. When the method was adopted, cracks 61 often appeared at the four corners of the opening 41 as shown in FIG. This is because, since the drawing depth of the arm body 11 is large, an unacceptable tensile stress acts on the periphery of the opening 41, which is a major obstacle in improving the product yield. Was. Disclosure of the invention

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a mouthpiece arm that prevents a work from cracking during a drawing process.

In order to solve the above-mentioned problems, in the present invention,

A rocking arm composed of an arm body, a shaft, and rollers,

(1) The arm body

(l a) — twin side walls,

(l b) a connecting wall connecting the pair of side walls,

(1 c) an opening penetrating between the connecting walls,

(Id) having a through hole at a position where the pair of side walls are aligned with each other,

(1 e) The opening of the arm body is formed by drawing a metal plate in which a punched hole with a relief at each corner is formed in advance, so that the pair of side walls and the connection wall can be separated from each other. When forming an integrated structure having a U-shaped cross section, it is formed by deformation of the punched hole,

(2) the shaft is inserted into the pair of through-holes, is bridged between the pair of side walls, (3) the roller is rotatably supported by the shaft,

Suggest something.

According to the present invention, even if the opening is pushed and expanded by the mold during the drawing process, the work is plastically deformed at the escape portion and the spread is smoothly performed, and no tensile stress which causes a crack is generated. . BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a vertical sectional view of a main part showing a valve train according to a first embodiment of the present invention. FIG. 2 is an enlarged sectional view taken along the line AA in FIG.

FIG. 3 is a perspective view showing the arm main body according to the first embodiment.

FIG. 4 is a plan view of the blank.

FIG. 5 is a perspective view showing an arm body according to the second embodiment.

FIG. 6 is a plan view of the blank.

FIG. 7 is a perspective view showing an example of a conventional arm body.

Hereinafter, an embodiment in which the present invention is applied to an outer fulcrum type rocker arm used in an 0H C engine will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a main part of the valve train according to the first embodiment, and FIG. 2 is an enlarged sectional view taken along the line AA in FIG.

As shown in these figures, the valve train of the first embodiment includes a camshaft 1 driven by a crankshaft (not shown) via a timing belt or the like, and a pivot shaft 3 formed on a cylinder head. The rocker arm 5 swings around a fulcrum, and the valve 7 is driven up and down in contact with the free end of the mouth rocker arm 5.

The kicker arm 5 includes an arm body 11 of a press-formed product made of a cold-rolled steel plate or the like, a pivot shaft 13 screwed to one end (base end) of the arm body 11, and an arm body. A roller 15 which is located substantially at the center of the cam 11 and is in contact with the cam lobe 1a of the camshaft 1 is a main component. The pivot shaft 13 is screwed into a boss 17 formed in the rocker arm 5 and then locked by a lock nut 19. Further, the mouthpiece 15 is rotatably fitted to the mouthpiece 23 press-fitted into the arm main body 11 via a needle bearing 21.

FIG. 3 is a perspective view of the arm main body 11. As shown in this figure, the arm body 11 has a U-shaped cross section including a pair of side walls 31 and 33 and a connecting wall 35 connecting the side walls 31 and 33. The arm body 11 has a roller holding portion 39 having a through hole 37 into which a roller pin 23 is inserted at a substantially central portion thereof, and a connecting wall 35 of the roller holding portion 39 has a lug 15. A rectangular opening 41 that exposes the upper part of the frame is formed. A female screw 43 with which the pivot shaft 13 is screwed is formed at the base end.

Hereinafter, the manufacturing process of the arm body 11 will be described.

In the case of the first embodiment, the operator first punches out a steel plate using a punch (not shown) to obtain a blank 51 shown in FIG. The blank 51 is formed in advance with a rectangular punched hole 55 that becomes an opening 41 during molding, and escapes 57 are further provided at the four corners of the punched hole 55.

Next, the worker draws the blank 51 (one or more times) using a drawing die (not shown) to obtain a peak in which the roller holding portion 39 protrudes upward. At this time, in the present embodiment, the reliefs 57 are provided at the four corners of the punched hole 55, so that even if the punched hole 55 is expanded by deep drawing, the work is plastically deformed at the location of the relief 57. The expansion will be carried out smoothly. The boss 17 is formed by bulging during the drawing process.

Next, the worker processes the work with a punch or tap (not shown) to complete an arm body 11 (FIG. 3) having a through hole 37 and a female screw 43.

In the present embodiment, since the arm body 11 is manufactured in such a process, an excessive tensile stress does not act around the formed opening 41, so that the crack which has been a problem in the conventional product can be prevented. Almost no generation occurred, and the product yield was greatly improved.

FIG. 6 is a perspective view showing an arm body according to the second embodiment, and FIG. 7 is a plan view showing the blank. As shown in FIG. 6, in the arm body of the second embodiment, the upper edge of the roller holding portion 39 has an arc shape. Therefore, as shown in Figure 7 As described above, the center of the punched hole 55 formed in the blank 53 is narrowed in an arc shape. Also in the case of the second embodiment, escapes 57 are formed at the four corners of the punched hole 55, and the crack of the arm main body 11 is prevented as in the first embodiment.

This concludes the description of the specific embodiment, but aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the present invention is applied to the outer fulcrum type rocker arm, but may be applied to the inner fulcrum type rocker arm. Also, various relief shapes can be adopted, and the location of the relief can be appropriately set according to the shape of the punched hole. Also, in a valve train employing a lash adjuster for the pivot, an adjustable pivot shaft is not required, so that a pivot projection can be integrally formed at the base end of the arm body. In addition, the specific configuration of the valve mechanism, including the specific shape and manufacturing process of the arm body, can be appropriately changed without departing from the gist of the present invention.

As described above, according to the present invention, there is provided a rocker arm including an arm body, a shaft, and a roller, wherein the arm body includes: a pair of side walls; a connection wall connecting the pair of side walls; An opening penetrating between the walls, and a through hole at a position where the pair of side walls are aligned with each other, wherein the opening of the arm main body has a punched hole formed with a relief at each corner. By forming a preformed metal plate by drawing, when forming an integrated structure of a U-shaped cross section composed of the pair of side walls and the connecting wall, it is formed by deformation of the punching hole. The shaft is inserted into the pair of through-holes and spans between the pair of side walls, and the roller is rotatably supported by the shaft. Even if the opening is pushed and expanded by The work is plastically deformed at the part, and the spread is performed smoothly, and the tensile stress that causes cracks is not generated, and the product yield is improved.

Claims

The scope of the claims

1. a rocker arm consisting of an arm body, a shaft, and rollers,

(1) The arm body is

(l a) — twin side walls,

(l b) a connecting wall connecting the pair of side walls,

(1 c) an opening penetrating between the connecting walls,

(1 d) having a through hole at a position where the pair of side walls are aligned with each other,

(1 e) The opening of the arm body is formed of the pair of side walls and the connection wall by performing drawing on a metal plate in which a punched hole having a relief formed in each corner is formed in advance. When forming an integrated structure with a U-shaped cross section, it is formed by deformation of the punched hole,

(2) the shaft is inserted into the pair of through holes, and is bridged between the pair of side walls;

(3) the roller is rotatably supported by the shaft,

Rocker arm.