JP2002195011A - Rocker arm - Google Patents

Abstract

(57) [Problem] To provide a rocker arm capable of securing the strength of a molding die and having a freedom in shape. A rocker arm 1 is formed by bending a flat piece of material and has a U-shaped cross section in which a pair of side walls 14 are formed. Further, the rocker arm 1 has a mounting portion 13 provided with a boss portion 132 and a screw hole 131. The mounting portion 13 is provided with the adjacent pieces 1 on both sides of the boss portion 132.
41. The rocker arm 1 makes the thickness t1 of the adjacent piece 141 smaller than the thickness t2 of the material piece so that the distance W1 between the inner side surfaces 145 of the adjacent piece 141 can be reduced.
To the inner surface 1 of the side wall 14 adjacent to the adjacent piece 141.
46 is larger than the interval W2 between the adjacent pieces 141.
A gap 130 is formed between the boss 132 and the boss 132.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm for transmitting a driving force for opening and closing a valve in an engine.

[0002]

2. Description of the Related Art As shown in FIGS. 9 (a), 9 (b) and 10 (a), a rocker arm 9 formed by pressing is formed by bending a flat piece of material to form a U-shaped cross section having a pair of side walls 94. It is formed into a shape. The rocker arm 9 has a support portion 91 at one end for supporting the valve stem portion of the valve, and an attachment portion 93 at the other end, which is attached to a pivot serving as a rotation center. When the mounting portion 93 is mounted on the pivot via an adjusting screw, the mounting portion 93 has a boss 932 for securing the mounting strength and a screw hole 931 for screwing the adjusting screw. Is provided.

[0003]

However, when the boss portion 932 is provided on the side having the side wall 94 in the rocker arm 9, the boss portion 932 and the side wall 94 avoid interference, so that the side walls 94 of the rocker arm 9 are connected to each other. The width B between them and the outer shape of the boss 932 are mutually restricted. Further, as shown in FIG. 10B, the bending is performed by the inner mold 9 located inside the U-shaped cross section.
5 and the outer mold 96 located on the outside,
, And are relatively moved so as to approach each other in opposite directions.

However, in the bending process, the thickness t of the gap disposing portion 951 of the inner die 95, which is a portion disposed adjacent to the boss portion 932, is reduced.
It is necessary to match the width of the gap 930 between the inner wall 94 and the inner surface 941 of the side wall 94. Therefore, for example, when the width B of the rocker arm 9 is reduced, or when the boss 932 is formed.
When increasing the outer shape of the boss, the boss 932 and the side wall 94
The gap 930 between the inner mold 94 and the inner side surface 941 becomes small, and the thickness of the gap arrangement portion 951 in the inner mold 95 becomes thin. Therefore, the strength of the gap arrangement portion 951 is insufficient,
It is difficult to form a rocker arm having a shape with a degree of freedom as described above.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a rocker arm which can ensure the strength of a molding die and has a flexible shape.

[0006]

According to the first aspect of the present invention, a flat plate-shaped piece is bent to form a pair of side walls and has a U-shaped cross section, and one end supports a valve stem portion of a valve. A rocker arm having, at the other end, a mounting portion attached to a pivot serving as a rotation center, and the mounting portion has a boss portion and a screw hole for screwing an adjustment screw. The mounting portion has an adjacent piece formed by extending a part of the side wall adjacent to both sides of the boss portion, and reducing the thickness of the adjacent piece to be smaller than the thickness of the material piece, thereby forming the adjacent portion. The distance W1 between the inner surfaces of the pieces facing each other is made larger than the distance W2 between the inner surfaces of the side walls adjacent to the adjacent pieces, and the adjacent piece and the boss portion are Gap W between
3 is a rocker arm.

It is most remarkable in the present invention that the mounting portion has the adjacent piece, and the thickness of the adjacent piece is smaller than the thickness of the material piece, so that the inner surface of the adjacent piece is formed. The gap between the adjacent pieces and the boss portion is formed to be larger than the gap between the inner side surfaces in the side wall portion.

Next, the function and effect of the present invention will be described.
In the rocker arm according to the present invention, a gap is formed between the adjacent pieces and the boss portion by increasing a distance between inner surfaces of the adjacent pieces facing each other. Therefore, the gap can be formed even if the lateral width, which is the width between the side walls of the rocker arm, is reduced, or if the outer shape of the boss is increased.

Since this gap can be formed, when the rocker arm is formed by bending a flat plate-shaped piece of material, the thickness of a portion corresponding to the gap in the forming die for performing the bending is reduced. It can be prevented from becoming thin. Therefore, the strength of the mold can be ensured, and a rocker arm having a flexible shape can be formed. The adjacent piece is formed by making its thickness smaller than the thickness of the material piece. Therefore, a rocker arm having a flexible shape can be formed without increasing the width of the rocker arm.

Next, it is preferable that the thickness of the adjacent piece is not less than 1/2 of the thickness of the side wall. Thereby, sufficient strength can be ensured for the adjacent piece.

Next, as in the third aspect of the present invention, it is preferable that the width of the gap W3 is at least の of the thickness of the material piece. Thereby, the strength of the mold can be easily secured.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows a rocker arm according to an embodiment of the present invention.
This will be described with reference to FIGS. 1 (a), 1 (b), 2
As shown in (a) and (b), the rocker arm 1 in this example is formed by bending a flat plate material piece.
It has a U-shaped cross section in which a pair of side walls 14 are formed.
Further, the rocker arm 1 has a support portion 11 for supporting the valve stem portion 31 of the valve 3 at one end, and a mounting portion 13 for mounting to a pivot 44 which is a center of rotation at the other end. The mounting portion 13 has a boss portion 132 and a screw hole 131 for screwing the adjusting screw 41 (see FIG. 3).

The mounting portion 13 is provided with the boss portion 13.
2 has an adjacent piece 141 formed by extending a part of the side wall 14 adjacent to both sides. Then, as shown in FIG. 2 (a), the rocker arm 1 makes the thickness t1 of the adjacent piece 141 smaller than the thickness t2 of the material piece so that the adjacent piece 141 is located between the inner surfaces 145 facing each other. Of the side wall 1 adjacent to the adjacent piece 141
The distance W2 between the inner side surfaces 146 where the portions 4 are opposed to each other
The adjacent piece 141 and the boss 1
A gap 130 is formed between the gap 130 and the gap 32.

The details will be described below. FIG. 1 (a),
As shown in FIGS. 2 (b) and 2 (a) and 2 (b), the rocker arm 1 has a side wall 14 at a position corresponding to both sides of the U-shaped cross section and a position corresponding to the bottom of the U-shaped cross section. Has a support portion 11 and a mounting portion 13. An opening 18 is provided between the support 11 and the mounting 13 at a position corresponding to the bottom. The rocker arm 1 has a support portion 11 and a mounting portion 13 on a side wall 14.
And a bearing portion 1 provided with a pair of shaft holes 121 for mounting a main shaft 211 of a roller 21 described later.
Two.

[0015] As shown in FIG.
The thickness t1 of 1 is 値 of the thickness t2 of the side wall 14. In addition, the width W3 of the gap 130 has a value of １ ／ of the thickness t2 of the material piece. In this example, the thickness t2 of the side wall 14 is substantially the same as the thickness t2 of the material piece. However, the thickness of the side wall 14 becomes smaller than the thickness of the material piece by bending performed in a U-shaped bending step described later. It may be slightly thinner than that.

The structure of the mounting portion 13 is effective both when the boss 132 is located on an imaginary plane extending from the inner surface 146 of the side wall 14 and when it is not located. In the present example, the boss 132 is not located on the virtual surface, and thus the gap 130 is formed even if the adjacent piece 141 is not provided. That is, the gap 130 in the present example is formed so as to increase the width W3.

The outer side surface 147 of the side wall is
There is no step between the portion and the portion of the bearing portion 12 which is a portion adjacent to the portion, and the portion has a planar shape.
In this example, the side wall 1 adjacent to the adjacent piece 141
The portion 4 is a portion of the bearing portion 12 and the adjacent piece 14
1, the distance W1 between the inner side surfaces 145 is
The gap 130 is formed to be larger than the interval W2 between the inner side surfaces 146 in FIG. The boss portion 132 is a protrusion protruding around the screw hole 131 in order to increase the length of the female screw in the screw hole 131, and is formed in a cylindrical shape in this example.

As shown in FIG. 3, a valve 3 for inhaling and / or exhausting a mixed gas or the like in the engine 6 is opened and closed by transmitting a driving force by rotation of a cam 22 by a rocker arm 1. When the cam 22 rotates, the roller 21 attached to the rocker arm 1 is driven to rotate, and at the same time, the cam 22 pushes down the rocker arm 1. At this time, the rocker arm 1 is moved to the pivot center 44 of the pivot 44.
1 and the bearing surface 111 of the bearing 11
Valve stem portion 3 of valve 3 abutting on bearing surface 111
1 is pushed down to open the valve 3. And
When the cam 22 further rotates, the valve 3 is closed by the retainer 33 fixed to the valve 3 being pushed up by the pushing force of the spring 32. Thus, the opening and closing operation of the valve 3 is performed.

The mounting portion 13 of the rocker arm 1
Is screwed into an adjusting screw 41 into a threaded hole 131 provided with a female thread, and this screwing is fixed with a nut 42, and is attached to the pivot 44. A spring 43 extends between the mounting portion 13 and the pivot 44.

In the present embodiment, the boss 132 is provided on the side of the rocker arm 1 on which the bearing surface 111 is formed. In contrast, FIG.
As shown in (b), the boss 132 may be provided on the side opposite to the side on which the bearing surface 111 is formed. Further, as shown in FIG.
May be formed so as to surround the periphery of the boss portion 132.

Next, a method of manufacturing the rocker arm 1 will be described. The rocker arm 1 in this example is formed by press working. First, as a thinning step, a portion of the flat material piece 101 where the adjacent piece 141 is formed is pressed to reduce the thickness of this portion to a thickness t1 (see FIG. 5A). A boss portion 132 and a screw hole 131 are provided in a portion where the mounting portion 13 is formed, and the mounting portion 13 is formed. The mounting portion 13 may be formed by forming a vertical wall around the hole, performing punching, and then cutting the internal thread. Alternatively, a weld nut serving as the boss portion 132 may be formed in the through hole. It may be formed by welding.

Next, as a punching step, unnecessary portions of the flat plate-shaped material piece 101 are cut off by a punching die (not shown), and the material piece 101 is expanded 102 of the rocker arm 1.
Formed. At this time, a punched hole 17 is provided in the central portion of the developed shape 102 (see FIG. 5A).

Next, as a U-shaped bending step, the material piece 101 is bent into a U-shaped cross section having a pair of side walls 14 with the bending lines L located on both sides 171 of the punched hole 17 as a starting point of bending (FIG. FIG. 5 (b)).
At this time, the punched hole 17 becomes the opening hole 18. After the bending, the interval W1 between the inner side surfaces 145 of the adjacent pieces 141 is determined by the bearing portion 12
Is larger than the interval W2 between the inner side surfaces 146 in the above, and between the boss portion 132 and the inner side surface 145,
The gap 130 having the width W3 is formed.

Next, as a bearing part forming step, the bearing surface 111 of the bearing part 11 is
It is formed so as to have a convex curved surface, and the shaft hole 1 is formed in the bearing portion 12 on the pair of side walls 14 as a shaft hole forming step.
21 is drilled. Thus, the rocker arm 1 is formed.

Next, the U-shaped bending step will be described in more detail. As shown in FIGS. 6 (a) and 6 (b), in the U-shaped bending step, in order to perform the above-mentioned bending, an inner mold 51 positioned inside a U-shaped cross section and an outer mold 52 positioned outside the U-shape.
Is used. The inner mold 51 has a concave portion 512 for avoiding interference with the mounting portion 13 and a gap arrangement portion 511 for forming the gap 130. The gap arrangement portion 511 is formed on both sides of the concave portion 512, and has a width W3 of the gap 130 formed by the thickness W4.
It is almost the same.

On the other hand, the outer die 52 has a concave groove 521 having a width W5 between the outer surfaces 147 of the bearing portion 12 of the rocker arm 1 to be formed. Then, with the material piece 101 having the developed shape 102 interposed between the inner mold 51 and the outer mold 52, the inner mold 51 and the outer mold 52 are relatively moved so as to approach each other in a direction facing each other and bent. I do.

Next, the operation and effect of this embodiment will be described. In this example, before performing the bending in the U-shaped bending step, the adjacent piece 141 is required in the thinning step.
Is thinned so as to have a thickness t1. Therefore, when performing the above-mentioned bending, the above-mentioned inner mold 5
The thickness of the gap disposing portion 511 is determined by the thickness t of the material piece 101.
It is possible to increase the thickness by subtracting the thickness t1 of the adjacent piece 141 from 2.

Therefore, the above-mentioned bearing portion 1 of the rocker arm 1 is provided.
In the case where the distance W2 between the inner side surfaces 146 of the inner mold 2 is narrow or the outer shape of the mounting portion 13 of the rocker arm 1 is large, the above-mentioned thickness W4 which is required for the gap arrangement portion 511 of the inner die 51 is secured. can do. Therefore, the strength of the molding die 5 can be ensured, and the rocker arm 1 having a flexible shape can be molded.

The adjacent piece 141 is formed by making the width W1 between the inner side surfaces smaller and making the thickness t1 smaller than the thickness t2 of the material piece. That is, since the width W5 of the rocker arm 1 between the outer surfaces 147 is not increased, the space occupied by the rocker arm 1 in the engine 6 does not increase.

Second Embodiment This embodiment is an example in which the rocker arm 1 is formed by a manufacturing method different from the manufacturing method described in the first embodiment.
That is, in the first embodiment, the thickness of the portion where the adjacent piece 141 is formed is reduced before the U-shaped bending step, whereas in the present embodiment, FIG.
As shown in (b), the thickness of the portion where the adjacent piece 141 is formed is reduced after the U-shaped bending step.

Hereinafter, a method of manufacturing the rocker arm 1 of the present embodiment will be described. First, in the same manner as in the first embodiment, the mounting portion 13 is formed, the blank 101 is formed into the developed shape 102 of the rocker arm 1 as a punching step, and the blank 101 is formed as a U-shaped bending step. The section U
Fold it into a letter shape. As shown in FIG.
In the character bending step, a protrusion 142 is formed by projecting the outer surface 147 of the portion forming the adjacent piece 141 of the side wall 14 outward, and the gap 130 is formed.

Next, as shown in FIG. 7 (b), as a handling step, the protrusion 142 is pressed on the U-shaped material piece 101 to reduce the thickness of the protrusion 142.
The adjacent piece 141 is formed. Then, as the bearing part forming step, the bearing surface 111 is formed, and as the shaft hole forming step,
The shaft hole 121 is formed. Thus, the rocker arm 1 is formed.

Next, the handling process will be described in more detail. As shown in FIGS. 8A and 8B, in the handling step, an inner mold 61 located inside the U-shaped cross section and an outer mold 62 located outside the U-shaped section are formed in order to form the adjacent piece 141.
Is used. The inner die 61 has a concave portion 612 for avoiding interference with the mounting portion 13 and gap arrangement portions 611 formed on both sides of the concave portion 612. 130. On the other hand, the outer die 62 is provided on the outer surface 14 of the bearing portion 12 of the rocker arm 1 to be formed.
7 has a concave groove 621 having a lateral width W5.

Then, the inner mold 51 is connected to the material piece 10.
The inner mold 61 and the outer mold 62 are relatively moved so as to approach each other in a direction in which the molds are arranged inward of each other. At this time, the protruding portion 142 is crushed by the outer mold 62, and the outer side surface 147 is formed as a flat surface between the adjacent piece 141 of the side wall 14 and the bearing portion 12. Thus, the adjacent piece 1
41 is formed. Other configurations are the same as those of the first embodiment. If possible, the bending in the U-shaped bending step and the handling in the handling step may be performed using the same molding die.

Also in the present embodiment, the strength of the forming die and the forming die 6 to be bent in the U-shaped bending step can be ensured, and the rocker arm 1 having a flexible shape can be formed. In addition, the same functions and effects as those of the first embodiment can be obtained.

[0036]

As described above, according to the present invention, it is possible to provide a rocker arm which can secure the strength of a molding die and has a degree of freedom in shape.

[Brief description of the drawings]

FIG. 1 is a diagram showing a rocker arm according to a first embodiment, (a) a perspective view, and (b) a side view.

FIGS. 2A and 2B are diagrams showing a rocker arm according to the first embodiment, wherein FIG. 2A is a plan view and FIG.

FIG. 3 is an explanatory view showing a rocker arm mounting structure according to the first embodiment.

FIG. 4 is a plan view showing (a) a rocker arm provided with a boss on the side opposite to the side on which the bearing surface is provided, and (b) a cross-sectional view taken along the line AA in (a) of the first embodiment. ,
(C) A plan view showing a rocker arm formed so that an adjacent piece surrounds the periphery of the boss.

5A and 5B are diagrams illustrating a method of manufacturing the rocker arm according to the first embodiment, wherein FIG. 5A is an explanatory diagram illustrating a punching process, and FIG.
Explanatory drawing which shows a U-shaped bending process.

FIGS. 6A and 6B are views showing a U-shaped bending step in the rocker arm manufacturing method according to the first embodiment, and are explanatory views showing (a) a state before bending and (b) a state after bending.

FIGS. 7A and 7B are diagrams illustrating a method of manufacturing the rocker arm according to the second embodiment, and FIG.
(B) Explanatory drawing which shows a handling process.

FIG. 8 is a view showing a handling step in a rocker arm manufacturing method according to the second embodiment, in which (a) a state before pressurization,
(B) Explanatory drawing which shows the state after pressurization.

9A is a perspective view of a rocker arm and FIG. 9B is a side view of the rocker arm in a conventional example.

10 (a) is a plan view of a rocker arm and FIG. 10 (b) is an explanatory view showing a molding die of the rocker arm in a conventional example.

[Explanation of symbols]

 1. . . Rocker arm, 11. . . Bearing, 13. . . Mounting part, 130. . . Gap, 131. . . Screw holes, 132. . . Boss part, 14. . . Side wall, 141. . . Adjacent pieces, 145,146. . . Inner surface, 3. . . Valve, 31. . . Valve stem section, 41. . . Adjusting screw, 44. . . Pivot, W1, W2. . . Interval, W3. . . Gap width, t1, t2. . . Thickness,

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G016 AA06 AA19 BA18 BB18 BB22 CA04 CA11 CA16 CA25 CA33 DA13 EA03 FA07 FA12 FA38 GA01

Claims (3)

[Claims] A flat plate-shaped piece is bent to form a pair of side walls, and has a U-shaped cross section. One end has a support for supporting a valve stem of a valve, and the other end has a turn. In a rocker arm having a mounting portion attached to a pivot serving as a moving center, the mounting portion having a boss portion and a screw hole for screwing an adjusting screw, the mounting portion is provided on both sides of the boss portion. By forming a part of the side wall extending adjacently to the adjacent piece and making the thickness of the adjacent piece smaller than the thickness of the material piece,
The distance W1 between the inner surfaces of the adjacent pieces opposing each other is made larger than the distance W2 between the inner surfaces of the side walls adjacent to the adjacent pieces opposing each other, so that the adjacent piece and the boss A rocker arm, wherein a gap W3 is formed between the arm and the part. 2. The rocker arm according to claim 1, wherein the thickness of the adjacent piece is at least half the thickness of the side wall. 3. The gap W3 according to claim 1, wherein
The width of the rocker arm is at least half the thickness of the material piece.