JP2001055913A - Rocker arm and manufacture of rocker arm body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To configure rocker arms against increases in their weight in freedom from design changes to their finished configuration and against defects during their manufacturing process at the same time. SOLUTION: A valve fitting portion 11 of a body is an inverted reentrant formed when one connecting wall once thickened id pressed. The thickening step compresses the perimeter of the connecting wall under pressure from the end face side. This obviates such problems or defects posed by forcible guided bending operations in conventional processes as cracks and surface sinks, and obviates reductions in rigidity posed by conventional processes when those regions of a metal plate which are to form sidewalls are compressed in the direction of thickness or thinned down, which as a result dispenses with thick metal plates used in conventional processes and requires no design change to a finished configuration for the rocker arm body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm which is tilted by a cam to open and close a valve provided on a cylinder head, and more particularly to a rocker arm having a sheet metal body.

[0002]

2. Description of the Related Art As a conventional rocker arm of this type, for example, a rocker arm disclosed in Japanese Patent Application Laid-Open No. 4-259611 is known.

This rocker arm is called an endpipod type in which a valve is opened and closed by being tilted by a cam with one end in a longitudinal direction as a fulcrum, and has a structure in which a roller is attached to a body.

The body has a pair of opposed side walls formed by bending a single metal plate into a substantially U-shaped cross section, and connecting walls connecting them at both ends in the longitudinal direction. And a pivot receiving portion into which the upper end of the pivot portion installed on the cylinder head is inserted into the connecting wall at the other end in the longitudinal direction.

[0005] The roller is rotatably supported on a pair of side walls of the body via a support shaft so as to partially protrude from a through hole provided between two connecting walls of the body.

In this prior art example, the valve fitting portion of the body is subjected to a bending process of making the body substantially U-shaped in section, and then one connecting wall of the body is pushed up to a position in the vertical direction between the pair of side walls. The shape is obtained by performing a bending process of forming an inverted M-shape when viewed from the end face.

[0007]

By the way, in the above-mentioned conventional example, since the valve fitting portion of the body is obtained by performing an unreasonable mold bending process for bending the body into an inverted M-shape, for example, FIG. As shown in (c), the outer surface of the bent portion between the pair of side walls 51 and 52 and the connecting wall 53 is liable to have a crack that causes a reduction in strength and a sink that causes a reduction in shape accuracy. be pointed out. Incidentally, shrinkage leads to an increase in the defective product occurrence rate, for example, the width dimension W of the valve fitting portion 50 varies.

[0008] On the other hand, the applicant of the present application has proposed connecting wall 53.
In order to increase the thickness by gathering the meat of other areas
It is considered that the bottom surface of the thickened connecting wall 53 is depressed to form an inverted concave valve fitting portion 50. For example, it has been considered that the inner surfaces of the pair of side walls 51 and 52 are pressed and compressed to reduce the thickness, and the plastic flowing wall portion accompanying the inner surfaces is gathered to the connecting wall 53. In this case, the thickness of the side walls 51 and 52 is thin. Therefore, the rigidity may be reduced. In order to avoid such a decrease in rigidity, it is necessary to take measures such as using a metal plate having a large thickness as a base material of the body or changing the design of the finished shape of the rocker arm body. Incidentally, in the former measure, the weight is forced to increase, and in the latter measure, the cost for design change is increased. There is room for improvement here.

In view of such circumstances, an object of the present invention is to provide a rocker arm having a shape capable of avoiding the occurrence of defects in the manufacturing process, and a shape capable of avoiding an increase in weight and a change in design of a finished shape.

[0010]

The first rocker arm of the present invention is tilted by a cam to open and close a valve provided on a cylinder head, and is formed by bending a single metal plate into a substantially U-shape. It has a body made of sheet metal provided with a pair of band-shaped opposing side walls and a connecting wall connecting them, and the thickness of the connecting wall of the body is increased by pressurizing and compression from the peripheral end surface thereof. An inverted concave valve fitting portion is formed to be depressed on the lower surface of the connecting wall.

[0011] In this configuration, since the valve fitting portion of the body is formed by increasing the thickness and depressing the body, the defects such as cracks and sinks which occur in the conventional bending process of the mold are eliminated. This eliminates the need for occurrence, and allows the width dimension of the valve fitting portion to be managed with high precision. In addition, in order to increase the thickness of the connecting wall, it is possible to cope with the problem by setting the external dimensions around the connecting wall to be large in advance as a prepared metal plate. This is advantageous in that, in addition to being able to avoid a decrease in rigidity that can occur when the material is compressed in the thickness direction to make it thin, it is easy to cope with an increase or decrease in the amount of increase in thickness when the thickness is increased.

According to the second rocker arm of the present invention, in the first rocker arm, a pair of side walls is provided at a longitudinally intermediate position between the pair of side walls.
The roller with which the cam comes into contact is rotatably supported via a support shaft in a state where the roller partially projects from a through hole provided in the middle of the connecting wall in the longitudinal direction.

In this configuration, the rocker arm is limited to the configuration having the body and the rollers, and the characteristic configuration of the valve fitting portion of the body is the same as that of the first invention.

The first method of manufacturing the rocker arm body according to the present invention is based on the premise that the body of the first or second rocker arm is manufactured, and the valve fitting portion is formed on a single metal plate punched into a required shape. Crushing the periphery of the region to be formed by pressurizing and compressing from the end face, collecting the plastically flowing meat portion with the region to increase the plate thickness, and depressing one surface of the region by press working A step of obtaining an inverted concave valve fitting portion, and by bending both sides of the metal plate in a region in which the valve fitting portion is provided in a manner to rise in the same direction as the recessed direction of the valve fitting portion. Obtaining a pair of side walls.

In this configuration, since the valve fitting portion is formed by the thickening process and the depressing process, the same effects as those of the first invention can be obtained.

According to the second manufacturing method of the rocker arm body of the present invention, the metal plate in the first manufacturing method is provided on two opposing sides in a region where the valve fitting portion is to be formed.
An overhanging piece that is to be crushed to increase the thickness of the region is provided.

In this configuration, when increasing the area where the valve fitting portion is to be formed, the overhanging piece provided in the area is crushed. This is advantageous in stabilizing the finished state of the rocker arm body as compared with the form of compressing the rocker arm.

According to the third method of manufacturing a rocker arm body of the present invention, in the thickening step in the first or second manufacturing method, one side of a metal plate is bulged.

With this configuration, in the process of depressing the thickened area after the thickening, it becomes easy to position the ceiling surface of the inverted concave valve fitting portion. This is because it becomes possible to specify the depression depth when forming the valve fitting portion with the non-bulging surface of the increasing connecting wall as a reference position.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on embodiments shown in the drawings.

FIG. 1 to FIG. 5 show an embodiment of the present invention. 1 is a side view of the rocker arm, FIG. 2 is an exploded perspective view of the rocker arm, FIG. 3 is a plan view of the rocker arm, FIG. 4 is an end view of the rocker arm viewed from the valve fitting portion side, and FIG. FIG. 4 is a view showing a manufacturing procedure of the first embodiment.

The rocker arm 1 shown in the figure has a cam 3 with one longitudinal end supported by a lash adjuster 2 as a fulcrum.
This is called an end-pipod type in which the valve 4 is opened and closed by being tilted by the body, and is composed of two elements of a body 5 and a roller 6.

The body 5 is provided with a pair of opposed side walls 7, 8 and two connecting walls 9, 10 by pressing and bending a single metal plate into a substantially U-shaped cross section by press working. The connecting wall 9 at one end is provided with an inverted recessed valve fitting portion 11 for receiving the upper end of the valve 4, and the connecting wall 10 at the other end in the longitudinal direction is a hemispherical convex pivot receiver 12 for receiving the upper end of the lash adjuster 2. Is provided.

The roller 6 is provided with a support shaft 14 and a plurality of shafts 14 on a pair of side walls 7 and 8 of the body 5 in a state where a part of the roller 6 projects from a through hole 13 provided between the two connecting walls 9 and 10 of the body 5. It is rotatably supported via a needle roller 15.

This embodiment is characterized in the method of manufacturing the body 5, particularly in the shape of the valve fitting portion 11 and the step of forming the same. Hereinafter, a method for manufacturing the body 5 will be described in detail.

First, one metal plate A is subjected to a stamping process by press working to obtain an outer shape as shown in FIG. At this time, the through holes 13 and the insertion holes 16 and 16 of the support shaft 14 are formed in required areas, and the projecting pieces 17 and 17 to be crushed in a later thickening step are formed.

Then, in the metal plate A, the area A1 where the valve fitting portion 11 is to be formed is increased. That is, the two overhanging pieces 17, 17 connected to the above-described area A1 are pressurized and compressed so as to be sandwiched from their end faces, as shown in FIG.
Fig. 5 shows the meat part which is crushed as shown in FIG.
As shown in (c), the sheets are gathered in the area A1 and the plate thickness is increased (thickening processing). At this time, although not shown, the upper surface of the area A1 is pressed down with a mold so that the area A1 swells only to the lower surface side.

Next, a semispherical convex pivot receiver 12 projecting upward from the connecting wall 10 at the other longitudinal end of the metal plate A.
Is obtained by performing a drawing process by press working. The step of forming the pivot receiver 12 may be performed after the step of forming the valve fitting portion 11 and the step of bending the metal plate A described below.

Thereafter, as shown in FIG. 5D, a half-punching process is performed on the region A1 having the thicker plate by pressing using two molds B and C as shown in FIG. An inverted concave valve fitting portion 11 that is depressed upward is formed. Note that the ceiling surface of the valve fitting portion 11 is curved in a semicircular arc shape, and this shape is formed by being transferred from the end surface shape of the lower mold C.

The two side portions A2 and A2 of the metal plate A
A2 is bent into a substantially U-shape along a dashed line in FIG. 5A by performing a mold bending process by press working using a mold D as shown in FIG. 5E. Thus, a pair of side walls 7, 8 and connecting walls 9, 10 are obtained. here,
When the mold D is applied to the metal plate A, the pivots of the regions A2 and A2 that can be the side walls 7 and 8 in the metal plate A are taken into consideration in consideration of a case where there is no more clearance for mounting the mold D on both sides of the pivot receiver 12. Both sides of the receiver 12 are thin.

The above-described forming process of the insertion hole 16 may be performed after the bending process of the side walls 7 and 8, and the forming process of the pivot receiver 12 may be performed after the forming process of the side walls 7 and 8. It may be performed after the bending process.

As described above, the valve fitting portion 11 is obtained by a half-punching process in which one of the connecting walls 9 is thickened so as to be depressed into an inverted concave shape. Variations in strength and shape accuracy due to defects can be eliminated, such as the occurrence of defects such as cracks and sinks, which have become problems in the complicated die bending process. As a result, it is possible to contribute to improvement in productivity and reduction in manufacturing cost, such as improvement in the production yield of the body 5. Furthermore, since the inner surface of the valve fitting portion 11 is obtained by shearing during the half-punching process, the width dimension W can be managed with higher precision, and the operability of the valve 4 by the valve fitting portion 11 is stabilized. For example, the operation stability of the valve 4 can be improved.

In the above embodiment, the metal plate A is provided with the overhanging pieces 17, 17 which are originally unnecessary.
Since one of the connecting walls 9 is thickened by crushing the walls 7 and 17, a reduction in rigidity that can occur when the region where the side wall is to be formed is compressed in the plate thickness direction to be thin as described in the conventional example. Can be avoided. Therefore, it is not necessary to use a thick metal plate A as in the conventional example, and it is advantageous in that the finished shape of the body 5 of the rocker arm 1 does not need to be changed. By adjusting the size of や す く, it is easy to cope with an increase or decrease in the amount of bulging during thickening, which is advantageous in that the degree of freedom in design can be increased.

In the above-described embodiment, since only one side of one connecting wall 9 is bulged in the thickening step, one side of this connecting wall 9 is depressed to fit the inverted concave valve. In the process of forming the part 11, the ceiling surface of the valve fitting part 11 is easily positioned. I mean,
This is because it becomes possible to specify the depression depth when the valve fitting portion 11 is formed with the non-bulging surface of the increasing connecting wall 9 as a reference position.

It should be noted that the present invention is not limited to only the above-described embodiment, and various applications and modifications are conceivable. (1) In the above embodiment, in order to increase the thickness of the connecting wall 9, the projecting pieces 17, 17 are provided only on two opposing sides of the metal plate A around the area A <b> 1 that can be the connecting wall 9. Although not shown, projecting pieces are further provided in the side wall forming regions A2 and A2 on both sides of the region A1.
All the overhanging pieces may be thickened by pressing and compressing them from four directions. (2) In the above embodiment, the roller 6 is supported on the support shaft 13 via the plurality of needle rollers 14. However, the roller 6 can be rotationally supported by sliding contact without using the needle roller 14. That is, the roller 6 is directly fitted to the support shaft 13 by a clearance fit,
Alternatively, although not shown, they can be fitted via a slide bearing such as a bush. (3) In the above embodiment, the end pivot type rocker arm 1 is illustrated, but the present invention can be applied to a center pivot type rocker arm (not shown).

[0036]

According to the present invention, defects such as cracks and sinks, which are problems in the unreasonable mold bending treatment presented in the conventional example, can be prevented from occurring in the valve fitting portion of the body, and the strength caused by the defects can be eliminated. And variations in shape accuracy can be eliminated. As a result, the production yield of the rocker arm body can be improved, thereby contributing to improvement in productivity and reduction in production cost. In addition, since the width dimension of the inner surface of the valve fitting portion can be managed with high precision, it is possible to contribute to improvement of the operation stability of the valve, such as stabilization of the valve operability by the valve fitting portion.

Further, in the present invention, the compression form when increasing the thickness of the connecting wall of the body is devised. Therefore, as described in the conventional example, the region where the side wall of the metal plate is to be formed is compressed in the plate thickness direction. In this case, it is possible to avoid a decrease in rigidity that occurs when the thickness is reduced. This is advantageous in that a thick metal plate as in the conventional example does not need to be used, and the finished shape of the rocker arm body does not need to be changed in design.

[Brief description of the drawings]

FIG. 1 is a side view of a rocker arm according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the rocker arm of the embodiment.

FIG. 3 is a plan view of a rocker arm.

FIG. 4 is an end view of the rocker arm viewed from a valve fitting portion side.

FIG. 5 is a view showing a manufacturing procedure of a rocker arm body;

FIG. 6 is an explanatory diagram for pointing out a defect of the conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rocker arm 2 lash adjuster 3 cam 4 valve 5 body of rocker arm 6 roller of rocker arm 7 one side wall of body 8 the other side wall of body 9 one connecting wall of body 10 other connecting wall of body 11 valve fitting part 12 pivot receiver 14 Roller spindle

Claims (5)

[Claims] 1. A rocker arm which is tilted by a cam to open and close a valve provided on a cylinder head, wherein a single metal plate is bent in a substantially U shape to form a pair of band-shaped opposed side walls and a pair of opposed side walls. A sheet metal body provided with a connecting wall to be connected, the thickness of the connecting wall of the body being increased by pressurization and compression from the peripheral end face thereof, and an upside down in which the connecting wall is depressed on the lower surface of the connecting wall; A rocker arm, wherein a concave valve fitting portion is formed. 2. The rocker arm according to claim 1, wherein a roller contacting a cam is provided at a middle of the pair of side walls in a longitudinal direction, with a roller partially projecting from a through hole provided at a middle of the connecting wall in a longitudinal direction. A rocker arm rotatably supported via a support shaft. 3. A method for manufacturing a body of a rocker arm according to claim 1, wherein a pressure is applied from a peripheral surface of a region where a valve fitting portion is to be formed to an end surface of one metal plate punched into a required shape. A step of crushing by compression and bringing together the plastic part which flows plastically to the area to increase the plate thickness, and a step of obtaining an inverted concave valve fitting part by depressing one surface of the area by pressing. Obtaining a pair of side walls by bending both side portions of the metal plate in a region where the valve fitting portion is provided in such a manner that both side portions rise in the same direction as the recessed direction of the valve fitting portion. A method for manufacturing a rocker arm body, which is characterized by the following. 4. The method for manufacturing a body of a rocker arm according to claim 3, wherein the metal plate has two sides facing each other in a region where the valve fitting portion is to be formed, for increasing the thickness of the region. A method for manufacturing a rocker arm body, characterized in that an overhanging piece to be crushed is provided. 5. The method for manufacturing a body of a rocker arm according to claim 3, wherein the thickening step is configured to bulge one side of the metal plate. Manufacturing method of the rocker arm body.