JP2001317311A - Locker arm and method of manufacturing its trunk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tapped hole capable of stably holding an adjusting screw while securing strength even if thickness of a trunk of a locker arm is reduced to make it light, and to restrain distortion of the tapped hole even when it is thermosetting-treated. SOLUTION: The end pivot type locker arm 10 to move to open and close a valve 60 arranged on a cylinder head as it is tilted with its one end side in the longitudinal direction as its fulcrum by a cam 20 has the sheet metal made truck 13 made as the one end side in the longitudinal direction of a pair of opposite side walls 11, 11 is connected by a connecting wall 12b, and thickness of a tapped hole formation planned region 12b2 on the connecting wall is increased as press working with thickness deflecting treatment by plastic flow against a peripheral part 12b1 of the connecting wall before a tapped hole 17 to be a tilting fulcrum is formed on the connecting wall of the truck.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end pivot type rocker arm provided in an engine valve opening / closing mechanism and a method of manufacturing a body thereof.

[0002]

2. Description of the Related Art When a cam rotates in conjunction with a crankshaft, an end pivot type rocker arm is tilted about a pivot portion at one end in a longitudinal direction of a body, so that a valve is received at a valve receiving portion at the other end in the longitudinal direction. To move it up and down.

In such a rocker arm body,
An adjusting screw is screwed into a screw hole at an end serving as a pivot portion, and the adjusting screw is supported by a tilt support portion installed on a cylinder head.

[0004]

The inventor of the present invention has made the body of such a rocker arm made of a sheet metal made of a single metal plate, and reduced the thickness of the body to reduce the weight. However, if the body thickness is reduced,
At one end in the longitudinal direction of the body, the length of the screw hole provided in the mounting portion of the adjusting screw becomes short, and the number of threads for obtaining stable holding of the adjusting screw cannot be secured.

Therefore, the present inventor has disclosed in Japanese Patent Application Laid-Open No. Hei 7-1509.
No. 09, in order to cover the shortage of the length of the screw hole, the adjusting screw mounting portion is subjected to a burring process so as to project from the body in a cylindrical shape, and a long screw hole is formed in the cylindrical portion. By forming the rocker arm, a rocker arm has been proposed in which the number of screw threads is increased as compared with the case described above, so that the stability of the adjusting screw can be improved.

However, in the case of the rocker arm proposed in the above proposal, in order to increase the number of threads that can be formed by lengthening the cylindrical portion in order to stably maintain the adjusting screw, since the body is originally thin, the burring process is required. The increase was limited.

Further, since the rocker arm body is made thinner, if the tubular portion is made longer by burring, the thickness of the tubular portion becomes thinner, so that the tubular portion is passed through an adjusting screw. Depending on the situation in which strong and weak forces are repeatedly applied to the cylindrical portion, there is a possibility that the cylindrical portion will be cracked. From this point, there is a limit in the burring process to lengthen the cylindrical portion.

Further, in the case of the burring process, in the course of a thermosetting treatment for securing rigidity to be performed thereafter, a difference in heat shrinkage caused by a difference in thickness between the adjusting screw mounting portion and the cylindrical portion causes a problem in the cylindrical portion. As a result of the distortion of the screw hole and the loss of roundness of the hole, there is a possibility that the adjusting screw is loosely attached or the adjusting screw is difficult to screw.

In view of the above, the present invention secures a screw hole having a length capable of stably holding the adjusting screw and having excellent mechanical strength, and also makes it possible to suppress distortion of the screw hole due to thermosetting treatment. That is the solution.

[0010]

(1) A rocker arm of the present invention is an end pivot type rocker arm which is tilted by a cam with one longitudinal end as a tilting fulcrum to open and close a valve disposed on a cylinder head. A pair of opposing side walls substantially parallel to each other, having at least one longitudinal end connected by a connecting wall to a body made of sheet metal, and forming a screw hole serving as a tilting fulcrum in the connecting wall of the body. Before performing the process, the thickness of the region where the screw hole is to be formed in the connecting wall is increased by performing a press working with a thickness deviation process by plastic flow on a peripheral portion of the connecting wall.

According to the present invention, the thickness of the peripheral portion of the connecting wall is gathered to the region where the screw hole is to be formed and the thickness of the region is increased, so that the length of the screw hole becomes longer. The adjusting screw can be stably held by increasing the number of threads formed on the adjusting screw.

Further, since the thickness of the peripheral wall of the screw hole is increased, even if a strong force is applied to the adjusting screw, there is no possibility that the peripheral wall will be cracked. It will be excellent.

Further, even if a heat curing treatment is performed after the above-mentioned thickening treatment, the thickness of the peripheral wall of the screw hole is increased, so that the distortion of the screw hole is suppressed, and the reliability of the adjustment screw in maintaining stableness is improved. Is high.

In the above, when the connecting wall is disposed above the pair of opposing side walls and the body is substantially inverted U-shaped when viewed from one longitudinal end, the mechanical strength of the screw hole is increased. Is preferred.

In the above, when an oil hole for discharging oil from the inside of the screw hole toward the roller side is formed in the thickened portion of the connecting wall, the lubricating oil in the screw hole is supplied through the oil hole to the roller, for example. Is preferably supplied to a bearing or the like for supporting the lubrication, thereby achieving lubrication.

(2) A method for manufacturing a rocker arm body according to the present invention is a method for manufacturing the rocker arm body,
A step of punching a single metal plate to obtain a developed shape of a sheet-metal body in which at least one longitudinal end of a pair of opposed side walls substantially parallel to each other is connected by a connecting wall; and a body in the developed shape. Pressing the peripheral portion of the connecting wall of the connecting wall with a thickness unevenness process by plastic flow to increase the thickness of a region where the screw hole is to be formed in the connecting wall; Forming a screw hole that penetrates through the hole.

According to the manufacturing method of the present invention, the peripheral portion of the connecting wall is gathered to the area where the screw hole is to be formed and the thickness of the area is increased, so that even if the body thickness is reduced, the screw is formed. The hole can be made sufficiently long, and a rocker arm body having a screw hole capable of stably holding the adjusting screw while securing strength unlike the burring process can be manufactured.

Further, according to the manufacturing method of the present invention, the thickness of the peripheral wall of the screw hole is increased, so that even if a strong force acts on the adjusting screw, there is no possibility that the peripheral wall will be cracked. A body having high strength and excellent reliability can be manufactured.

Further, according to the manufacturing method of the present invention, even if a thermosetting treatment is performed after the above-mentioned thickening treatment, the thickness of the peripheral wall of the screw hole can be increased as compared with the case of burring. The rocker arm body in which the distortion of the screw hole can be suppressed even by the hardening process can be manufactured.

In the above-mentioned manufacturing method of the present invention, the press-processed peripheral portion is bent substantially at right angles to the connecting wall of the unfolded body so that the pressed surfaces face each other, and the body is connected to one end in the longitudinal direction. It is preferable to include a step of forming a substantially U-shape when viewed from the side, since a rocker arm body in which the peripheral wall strength of the screw hole is further increased can be manufactured.

[0021]

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

1 to 3 show an end pivot type rocker arm according to an embodiment of the present invention.
1 is a longitudinal side view, FIG. 2 is a plan view thereof, and FIG.
It is the front view.

In these figures, 10 is a rocker arm, 20 is a cam, 30 is an adjusting screw, 40
Is an nut, 50 is an adjusting screw receiving member, 6
0 is a valve.

The rocker arm 10 shown in the figure has a body 13 having a pair of opposed side walls 11, 11 facing in parallel in the longitudinal direction, both ends of which in the longitudinal direction are integrally or separately connected by connecting walls 12a, 12b. ing.

A roller 1 supported between the opposing side walls 11 and 11 against which the cam 20 abuts is disposed in the middle of the body 13 in the longitudinal direction.
4 is rotatably attached to the support shaft 15 via a bearing 16. In this mounted state, the roller 14 is in a state of partially projecting from the through hole 11a between the connecting walls 121 and 12b.

The connecting wall 12a at one longitudinal end of the body 13
Is a chip-shaped member separate from the body 13 and serves as a valve receiving portion that comes into contact with the valve 60.

The connecting wall 12b at the other end in the longitudinal direction of the body 13
Has a flat surface integral with the body 13 and is formed with a screw hole 17 penetrating in the plate thickness direction, and the adjusting screw 30 is screwed into the screw hole 17 to form an adjusting screw mounting portion.

The adjusting screw 30 has a nut 40 screwed to the upper protruding portion from the body 13, and the hemispherical head portion 30 a of the lower protruding portion is received by a receiving member 50 provided on a cylinder head of the engine. ing.

The hemispherical head 30a of the body 13 is received by the receiving concave surface of the receiving member 50 in a state where the adjusting screw 30 has its lower protrusion amount adjusted by the nut 40.

The body 13 has a screw hole 17 as a tilting fulcrum.

In the rocker arm 10 of this embodiment, a screw hole 17 is provided which allows the adjusting screw 30 to be stably held while maintaining the strength even if the plate thickness is reduced in order to make the body 13 lightweight. Further, it is characterized in that it has a structure in which the distortion of the screw hole 17 can be suppressed even by the heat curing treatment.

More specifically, the rocker arm 10 according to the present embodiment has a structure in which the peripheral wall 12b of the connecting wall 12b is formed before the screw hole 17 serving as a tilting fulcrum is formed in the connecting wall 12b of the body 13.
b1 is subjected to press working with uneven thickness treatment by plastic flow, and a screw hole forming region 1 in the connecting wall 12b is formed.
The structure is such that the thickness of 2b2 is increased.

With the above structure, this rocker arm 10
Is that the thickness of the peripheral portion 12ba of the connecting wall 12b is gathered in the screw hole forming area 12b2 and the thickness of the area is increased, so that even if the body 13 is thin, the screw hole is formed. It is possible to form the screw hole 17 whose strength is increased with respect to the predetermined area 12b2 and which can hold the adjusting screw 30 stably.

Further, in this case, even if a heat hardening treatment is performed after the above-mentioned thickening treatment, since the thickness of the peripheral wall of the screw hole 17 is increased, the distortion of the screw hole 17 is suppressed, and the adjustment is performed. The screw 30 does not become loose in the screw hole 17 and the reliability of the holding thereof is high.

Next, a procedure for manufacturing the body 13 of the rocker arm 10 will be described with reference to FIGS.

Here, FIG. 4A is a plan view of the fuselage in an unfolded state for explanation of the first step of the method of manufacturing the fuselage, and FIG. 4B is a plan view of FIG. a) View from the arrow line, FIG.
FIG. 5A is a plan view of the body for explaining the second step, and FIG.
FIG. 5B is a view taken along line (b)-(b) of FIG.
FIG. 6A is a plan view of a body used for explaining a third step, and FIG.
(B) is a view taken along line (c)-(c) of FIG.
FIG. 7A is a plan view of the body used for explaining the fourth step, and FIG.
FIG. 7B is a view taken along line (d)-(d) of FIG.
FIG. 8A is a plan view of a body used for explaining a fifth step, and FIG.
FIG. 9B is a view taken along line (e)-(e) of FIG.
FIG. 9 is a cross-sectional view of a main part of the body for explaining a method of forming an oil hole.

One metal plate was punched out, and FIG.
A body 13 having a developed shape as shown in FIG.
The body 13 has no screw hole 17 formed therein.

Next, as shown in FIGS. 5A and 5B,
A pressurizing and compressing process is performed on the peripheral portion 12b1 of the connecting wall 12b by a press process accompanied by a thickness variation process by plastic flow.

Due to the press working, the flesh of the peripheral portion 12b1 plastically flows by the above-mentioned pressurizing and compressing process and gathers in the screw hole forming area 12b2 to form the screw hole forming area 12b.
The thickness of the sheet No. 2 is increased.

As a result, assuming that the initial thickness of the connecting wall 12b of the body 13 before the press working in the developed shape is t0, the thicknesses of the peripheral portion 12b1 and the screw hole forming area 12b2 before the press working are equal. Although it is t0, the plate thickness of the peripheral portion 12b1 after the press working is the connecting wall 12b.
T1 (<t0), which is smaller than the initial plate thickness t0, and
The plate thickness of the screw hole forming region 12b2 is t2 (> t0) which is larger than the plate thickness t0.

Next, the pressed peripheral portion 12b1 is bent substantially at right angles to the connecting wall 12b of the expanded body 13 so that the pressed surfaces face each other, and the body 13 is bent at one end in the longitudinal direction. Almost reverse U
It should be a letter shape. Thus, the body 13 shown in FIGS. 6A and 6B is obtained.

In this case, the peripheral portion 12b1 of the connecting wall 12b
The end portions on the side of the opposing side walls 11
Since they are connected to the end portions 1 and 11, they are further away from the side surface of the screw hole forming area 12 b 2 toward the opposite end portion, and are separated by the distance d at the opposite end portion. .

If the peripheral portion 12b1 is separated from the side surface of the screw hole forming area 12b2 in this way, it is disadvantageous in strength, and also comes into contact with parts around the engine where the rocker arm is arranged and interferes with each part. Because it ’s easier to do
As shown by arrows in FIG. 6B, both peripheral portions 12b1 are pressed toward the side surface of the screw hole forming area 12b2, and FIG.
(A) As shown in (b), both the peripheral portions 12b1 are brought into contact with the side surfaces of the screw hole formation scheduled region 12b2.

As a result, the strength of the connecting wall 12b itself is sufficiently ensured.
By 1, the strength can be ensured in addition, and interference due to contact with parts around the engine can be prevented.

The plate thickness of the screw hole forming area 12b2 of the connecting wall 12b of the body 13 manufactured in this way is sufficiently large, and therefore, as shown in FIGS. The screw hole 17 penetrating in the plate thickness direction of the predetermined area 12b2 can be formed, and as a result, the long screw hole 17 can be formed.

As shown in the side sectional view of FIG. 9, an oblique oil hole 12c through which oil is discharged from the screw hole 17 toward the roller 14 is formed through the connection wall 12b in a thickened portion thereof.

The oblique oil hole 12c is formed as a conical hole 12c1.
And a large-diameter through-hole 12c2 and a small-diameter through-hole 12c3. The small-diameter through-hole 12c3 is located on the screw hole 17 side, and the large-diameter through-hole 12c2 is connected to the connecting wall 12b.
It is located on the top side.

The small-diameter through-hole 12c3 is appropriately set to a diameter and a length that can secure the pressure of the oil to be discharged. The large-diameter through-hole 12c2 is appropriately set to a diameter that can ensure workability.

The adjusting screw 30 has an axial oil hole 30b extending from the hemispherical head 30a to an intermediate portion of the main body, and a radial oil hole 30c communicating with the oil hole 30b.
And an annular groove 30d is formed in the circumferential direction passing through the radial oil hole 30c.

When the adjusting screw 30 is attached to the screw hole 17, the hemispherical head 3
Oil between the oil receiving hole 0a and the concave receiving surface of the receiving member 50 passes through the oil holes 30b and 30c of the adjusting screw 30, and further passes through the oil holes 12c of the connecting wall 12b to lubricate the cam 20 and the bearing 16 of the roller 14. Supplied as oil.

[0051]

As described above, according to the rocker arm of the present invention, the region in which the screw hole is to be formed has a structure in which the wall thickness of the peripheral portion of the connecting wall is gathered to increase the thickness. Therefore, even if the body is thin, the length of the screw hole formed in the screw hole forming area is sufficiently long, so that the adjusting screw can be stably held in the screw hole. Since the peripheral wall of the screw hole is thickened, the strength of the screw hole is also increased.

In the rocker arm of the present invention, the thickness of the peripheral wall of the screw hole is large, so that when a strong force acts on the just screw, there is no possibility that the peripheral wall is cracked, and the mechanical strength is high. It will be excellent.

In the rocker arm of the present invention, even if a heat hardening treatment is performed after the above-mentioned thickening treatment, since the peripheral wall of the screw hole is thickened, the distortion of the screw hole is suppressed, and the adjusting screw is stably held. Has high reliability.

Further, according to the method of manufacturing the rocker arm body of the present invention, the peripheral portion of the connecting wall is gathered to the area where the screw hole is to be formed and the thickness of the area is increased, so that the body is made thinner. Also, the screw hole can be made sufficiently long, and a body having a screw hole capable of stably holding the adjusting screw while ensuring strength can be manufactured. Also,
According to this manufacturing method, it is possible to manufacture a body in which the distortion of the screw holes is suppressed even when the thermosetting treatment is performed after the thickening treatment.

[Brief description of the drawings]

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

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a front view of FIG. 1;

FIG. 4 (a) is a plan view of the fuselage for explaining the first step in the method of manufacturing the fuselage, and FIG. 4 (b) is (a) of FIG.
ー (a) View from line

FIG. 5A is a plan view of the body used for explaining a second step in the method of manufacturing the body, and FIG. 5B is a plan view of the body shown in FIG.
ー (b) View from line

FIG. 6A is a plan view of the body used for explaining a third step in the method of manufacturing the body, and FIG.
ー (c) View from arrow

FIG. 7A is a plan view of a body for explaining a fourth step in the method of manufacturing the body, and FIG. 7B is a plan view of FIG.
ー (d) View from arrow

FIG. 8A is a plan view of the body used for explaining a fifth step in the method of manufacturing the body, and FIG.
ー (e) View from the arrow

FIG. 9 is a cross-sectional view of a main part of the fuselage for explaining formation of an oil hole in the method of manufacturing the fuselage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rocker arm 11 Opposite side wall 12a, 12b Connecting wall 13 Body 14 Roller 15 Support shaft 16 Bearing 17 Screw hole 20 Cam 30 Adjust screw 40 Nut 50 Adjust screw receiving member 60 Valve

Claims (6)

[Claims] An end pivot type rocker arm which is tilted by a cam with one longitudinal end as a tilting fulcrum to open and close a valve disposed on a cylinder head, wherein a pair of opposing side walls substantially parallel to each other are provided. At least one longitudinal end thereof is connected by a connecting wall, and the connecting wall of the body has plasticity with respect to a peripheral portion of the connecting wall before a screw hole serving as a tilting fulcrum is formed in the connecting wall. A rocker arm, wherein a thickness of a region where a screw hole is to be formed in the connecting wall is increased by performing a press process with a thickness deviation process by a flow. 2. The rocker arm according to claim 1, wherein said connecting wall is disposed above a pair of opposing side walls, and said body is substantially inverted U-shaped when viewed from one longitudinal end. Rocker arm. 3. The rocker arm according to claim 2, wherein a roller abutting the cam at an intermediate portion in the longitudinal direction of the body is supported in a state in which the roller partially projects from a through hole provided at an intermediate portion in the longitudinal direction of the connecting wall. A rocker arm rotatably supported via a shaft. 4. The rocker arm according to claim 1, wherein an oil hole for discharging oil from inside the screw hole toward the roller is formed in the thickened portion of the connecting wall. . 5. A method for manufacturing a body of a rocker arm according to claim 1, wherein one metal plate is punched out and at least one longitudinal end of a pair of opposing side walls substantially parallel to each other is connected. A step of obtaining a developed shape of the body made of sheet metal joined by a wall, and performing a press working with a thickness deviation process by plastic flow on a peripheral portion of the connecting wall of the body in the developed shape, A method for manufacturing a rocker arm body, comprising: a step of increasing a thickness of a region in which a screw hole is to be formed; and a step of forming a screw hole penetrating in a thickness direction in the increased thickness portion. 6. The method of manufacturing a rocker arm body according to claim 5, wherein said pressed peripheral portions are bent substantially at right angles to a connecting wall of said expanded body in such a manner that pressed surfaces face each other. A method for manufacturing a rocker arm body, comprising a step of making the body substantially U-shaped when viewed from one longitudinal end side.