JP3497373B2 - Rocker arm and method of manufacturing the same - Google Patents

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 opening and closing a valve provided on a cylinder head in accordance with rotation of a cam in a valve mechanism for an internal combustion engine of a vehicle, and a method for manufacturing the rocker arm.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing a valve mechanism in an internal combustion engine of a vehicle. As shown in the figure, the valve mechanism includes a cam (3) that rotates in conjunction with the crankshaft (2).
A rocker arm (1) is provided for converting the rotational movement of the above into a reciprocating linear movement of a valve stem (5) in a valve (4) such as an intake valve and an exhaust valve.

This rocker arm (1) has a pair of side walls (1) arranged in parallel as shown in FIGS. 8 and 9.
1) and one end connecting wall (12) and the other end connecting wall (13) connecting one end part and the other end part of both side walls (11). Then, the support shaft (8) of the roller (7) is fixed in the shaft fixing hole provided in the longitudinal intermediate region of the side walls (11), and the roller (7) and the cam (3) are It is configured to be in rolling contact. Further, a pivot engaging recess (13a) is formed on the lower surface side of the other end connecting wall (13) of the rocker arm (1), and a pivot part (6) fixed to the cylinder head is formed in this recess (13a). ) Is arranged in an engaged state, and the tip of the valve stem (5) is arranged in contact with the lower surface of the one end coupling wall (12). In addition, one end connecting wall (12)
A valve stem guide groove (12a) is formed on the lower surface side of the valve stem (5a).
a), and the valve stem tip is placed in the groove wall (both side walls 1
The locker arm (1) is prevented from being displaced in the horizontal direction with the pivot part (6) side as a fulcrum by locking the rocker arm (1) at the lower edge part (1).

[0004]

The rocker arm (1) as described above has a complicated shape, for example, a guide groove (12a) for accommodating the tip of the valve stem is provided in the one end connecting wall (12). In addition, since it is necessary to have sufficient rigidity, it is customary to manufacture it by forging or precision casting (lost wax).

However, the rocker arm (1) is
When it is manufactured by a low-efficiency machining such as forging or precision casting, there is a problem that the production efficiency is lowered and the cost is increased.

On the other hand, in recent years, the weight of rocker arms is desired to be reduced in order to reduce the inertial weight as the internal combustion engine is rotated at high speed and output is increased. Have been proposed.

However, since the rocker arm has a complicated shape such as the guide groove (12a), the number of man-hours increases in the conventional press working, and it is difficult to form the guide groove (12a) with sufficient accuracy. Therefore, there is a problem that the production efficiency is lowered and the cost is increased.

The present invention solves the above-mentioned problems of the prior art, improves the production efficiency and reduces the cost, and provides a rocker arm having a highly accurate valve stem guide groove and a manufacturing method thereof. To aim.

[0009]

In order to achieve the above object, the rocker arm of the first aspect of the present invention connects a pair of both side walls and one end portion of the both side walls, and a valve stem tip is provided on the lower surface side. A valve stem guide groove for accommodating the tip of the valve stem by pressing a punch into the one end connecting wall from the lower surface side and plastically deforming the one end connecting wall. Formed and before
The width of the pressing punch is “W”, and the inner spacing between the both side walls is
When “S” is set, the dimensions are set so that the relational expression W ≧ S holds.
What is set is the gist.

In the rocker arm according to the first aspect of the present invention, the valve stem guide groove is formed in the one end connecting wall by the pressing punch being driven and plastically deformed. For example, forging, precision casting, etc. Pressing with excellent productivity without using low-efficiency machining (pressing)
Thereby, the valve stem guide groove can be formed efficiently.

Further, since the valve stem guide groove is formed corresponding to the shape of the pressing punch, the dimensional accuracy does not vary and high accuracy can be obtained.

In the first aspect of the invention, it is preferable to adopt a structure in which the bottom surface of the valve stem guide groove is formed into a predetermined curved surface by driving the pressing punch.

That is, when this structure is adopted, for example, when assembled in a valve mechanism of an internal combustion engine, the tip of the valve stem can be smoothly brought into sliding contact with the bottom surface of the valve stem guide groove, and the valve can be opened and closed. The operation can be performed smoothly. Furthermore, by driving the pressing punch, the valve stem guide groove and the curved surface can be formed at the same time.
As compared with the case where these are performed in separate steps, the manufacturing can be performed more efficiently.

On the other hand, the method of manufacturing the rocker arm of the second aspect of the present invention comprises a step of obtaining a metal plate-like processed product having a predetermined shape,
By bending the plate-shaped product, a pair of both side walls,
A step of obtaining a bent product having one end connecting wall configured to connect one ends of both side walls thereof and to which a valve stem tip is brought into contact with a lower surface side; and one end of the bent product By forming a valve punch guide groove for accommodating the valve stem tip at the same time by forming a pressing punch from the lower surface side into the connecting wall to plastically deform, the bottom surface of the valve stem guide groove is formed into a predetermined curved surface. "W" and a step <br/> seen including, the width of the pressing punches, the inside of the side walls
When the interval is “S”, the relational expression W ≧ S holds.
The gist is that the dimensions are set .

The rocker arm manufacturing method of the second aspect of the invention specifies one mode of the manufacturing process of the rocker arm of the first aspect of the invention.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a rocker arm which is an embodiment of the present invention will be described in detail according to a manufacturing procedure with reference to the drawings. In the following drawings, the rocker arm (including the intermediate processed product) is shown in a state in the manufacturing process, that is, a state in which the rocker arm is vertically inverted with respect to the actual use state. However, in the following description, The “upper side” of the drawing will be described as “lower side” according to the actual use state.

First, in manufacturing the present rocker arm, as shown in FIG.
A substantially rectangular punched plate having arcuate convex portions on both edges is obtained, and the center of the punched plate is punched to obtain a blank processed product (20a) having a drum-shaped hole.

Next, a semi-spherical pivot engaging recess (24), which will be described later, is formed in a predetermined region of the blank processed product (20a) by overhanging, and then the blank processed product (20a) is formed as shown in FIG. Then, a bending process is performed to obtain a bent product (20b).

This bent product (20b) is formed in a U-shape in end view, and has a pair of opposite side walls (2).
2), one end connecting wall (30) connecting between one end lower ends of both side walls (22) and the other end connecting wall (23) connecting other end lower ends, and a pair of both side walls An opening for accommodating and allowing the roller to be seen is provided between the one end connecting wall (30) and the other end connecting wall (23) between (22). The pivot engaging recess (24) described above is
It is arranged in the center of the lower surface side of the other end connecting wall (23).

Next, the bent product (20
b) One end connecting wall (30) has a valve stem guide groove (4
0) is formed by pressing.

That is, in this pressing process, the restraining mold (50) and the pressing mold (60) shown in FIGS. 5 and 6 are used. Restraint die (50) is a bent product (20b)
Of the side wall (22) on one end side (end part of the valve stem abutting side) of the side wall of the two side wall restraining recesses (51) capable of restraining the inner side surface, the outer side surface and the end surface of the side wall (22). An area corresponding to the upper surface is formed on a predetermined curved surface (52) described later. Further, the pressing die (60) has a guide groove forming pressing punch (62) corresponding to the lower surface side intermediate region of the one end connecting wall (30) of the bent product (20b),
Further, guide wall forming recesses (61) are formed on both sides of the pressing punch (62).

Then, at a predetermined position of the restraining die (50),
The bent product (20b) is set, the pressing die (60) is driven in as shown in FIG. 6, and the pressing punch (62) is set.
Thus, the one end connecting wall (30) is pressed and deformed from the lower surface side to the upper surface side.

As a result, one end side of the bent product (21) is plastically deformed into a shape corresponding to the inner surfaces of the restraining mold (50) and the pressing mold (60), and specifically, the one end connecting wall (3).
The intermediate region of 0) is deformed so as to be depressed upward, and both sides thereof are deformed so as to be bulged by the movement of the workpiece material, thereby forming the guide groove (40) having the guide walls (41) on both sides. Further, as shown in FIG. 7, the bottom surface of the guide groove (40) is
Corresponding to the curved surface (52) of the restraining die (50), it is formed as a curved surface (42) having a predetermined radius of curvature so that it can be smoothly slidably contacted with the tip of the valve stem. In addition, in FIG. 6, for reference, a bent product (20
The state of b) is shown by a broken line.

Thus, as shown in FIG. 3, the pressed product (2) having the guide groove (40) in the one end connecting wall (30) is provided.
0c) is obtained.

Here, as shown in FIGS. 5 and 6, the width dimension of the pressing punch (62) of the pressing die (60) is "W", the inner spacing of the side walls (22) is "S", and the side walls are When the width dimension (plate thickness) of (22) is “T”, it is necessary to set the dimensions so that the relational expression W ≧ S is satisfied, and more preferably W ≧ 1 / 3T + S + 1 / 3T, W ≦ 2 / 3T + S +
It is preferable to set the dimensions so that the relational expression of 2 / 3T is satisfied. That is, when the width W of the pressing punch (62) is too large, the plate thickness of the guide wall (41) becomes too thin,
It may be difficult to obtain sufficient strength, and conversely, if the width dimension W is too small, at the time of press working, the inner corner portion between the one end connecting wall (30) and the both side walls (22) and The shear phenomenon may occur between the bottom surface of the guide groove (42) and the inner corner between the guide walls (41), and cracks may occur.

On the other hand, after the pressing work is completed, punching punches are punched from both sides, for example, in the longitudinal middle portion of the both side walls (22), and as shown in FIG. A shaft fixing hole (21) is formed at the position so that the shaft centers thereof coincide with each other.

This completes the manufacture of the rocker arm (20).

According to the manufacturing method of this embodiment, the rocker arm (20) is manufactured only by press working such as outer diameter punching, bending, pressing and punching. It is possible to improve production efficiency and reduce costs without requiring low-efficiency machining such as forging and precision casting.

Particularly in the pressing process, the pressing punch (6
Since the valve stem guide groove (40) is formed by driving 2), the guide groove (40) is formed corresponding to the shape of the die punch (62). Therefore, the dimensional accuracy of each product does not vary, and the rocker arm (20) having the guide groove (40) with high dimensional accuracy can be efficiently produced.

The rocker arm (20) of this embodiment is also used.
Since the bottom surface of the guide groove (40) is formed into a curved surface (42) having a predetermined radius of curvature, the valve stem tip is attached to the bottom surface of the guide groove (40) when assembled in the valve mechanism. The sliding contact can be made smoothly, and the opening / closing operation of the valve can be smoothly performed.

Moreover, in this embodiment, the guide groove (40) is formed by driving the die punch (62).
Since the curved surface (42) is formed at the same time, the curved surface (42) can be manufactured more efficiently as compared with the case where these are performed in separate steps, and further, low efficiency machining such as cutting is used. Since it does not exist, it can be produced more efficiently.

[0032]

As described above, according to the rocker arm of the first aspect of the present invention, the valve stem guide is formed by driving the pressing punch into the one end connecting wall that connects the one end portions of the both side walls to plastically deform it. Since the groove is formed, it can be produced more efficiently and the cost can be reduced as compared with the case where the guide groove is formed by using low efficiency machining such as forging and precision casting. it can. Further, since the valve stem guide groove is formed corresponding to the shape of the pressing punch, there is an effect that there is no variation in dimensional accuracy and a high dimensional accuracy can be obtained as a guide groove.

Further, in the first aspect of the present invention, when the bottom surface of the valve stem guide groove is formed into a predetermined curved surface by driving with the pressing punch, the tip end of the valve stem is smoothly fitted to the bottom surface of the valve stem guide groove. Since they can be brought into sliding contact with each other, the opening / closing operation of the valve can be smoothly performed. Furthermore, since the valve stem guide groove and the curved surface are formed at the same time by driving the pressing punch, it is possible to more efficiently produce them as compared with the case where they are performed in separate steps. Moreover, since low efficiency machining such as cutting is not used, there is an advantage that the production efficiency can be further improved.

On the other hand, since the rocker arm manufacturing method of the second aspect of the invention specifies one mode of the manufacturing process of the rocker arm of the first aspect of the invention, it is possible to manufacture a rocker arm having the above effects. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a perspective view showing a blank processed product as an intermediate processed product in a rocker arm manufacturing method according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a bent product as an intermediate product in the manufacturing method of the embodiment.

FIG. 3 is a perspective view showing a pressed product as an intermediate product in the manufacturing method of the embodiment.

FIG. 4 is a perspective view showing a rocker arm manufactured by the manufacturing method of the embodiment.

FIG. 5 is a cross-sectional view showing the bent product of the embodiment immediately before pressing.

FIG. 6 is a cross-sectional view showing the bent product of the embodiment in the state of being pressed.

FIG. 7 is a cross-sectional view showing a rocker arm of the embodiment.

FIG. 8 is a sectional view showing a valve mechanism of an internal combustion engine in a conventional vehicle.

FIG. 9 is a cross-sectional view showing a rocker arm applied to a conventional valve mechanism.

[Explanation of symbols]

20 ... Rocker arm 20a ... Blank processed product (plate processed product) 20b: bent product 22 ... Both side walls 30 ... One end connection wall 40 ... Valve stem guide groove 42 ... Curved surface 62 ... Press punch

Continuation of the front page (56) Reference JP-A-63-194837 (JP, A) JP-A-6-79383 (JP, A) JP-A-5-86819 (JP, A) JP-A-4-272310 (JP , A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01L 1/18 B21D 53/84

Claims (3)

(57) [Claims] 1. A pair of both side walls, and one end connecting wall configured to connect between one end portions of the both side walls and to contact a tip end of a valve stem on a lower surface side, the one end connecting wall to, from the lower surface side is driven pressing punch by plastic deformation, the valve stem guide groove for accommodating the valve stem tip is formed, the width of the pressing punch "W", the inner spacing of the side walls
When “S” is set, the dimensions are set so that the relational expression W ≧ S holds.
Rocker arm characterized by being set . 2. The rocker arm according to claim 1, wherein the bottom surface of the valve stem guide groove is formed into a predetermined curved surface by driving the pressing punch. 3. A step of obtaining a metal plate-shaped product having a predetermined shape, a bending process being performed on the plate-shaped product, and a pair of both side walls,
A step of obtaining a bent product having one end connecting wall configured to connect one end portions of both side walls thereof and to which a valve stem tip is brought into contact with a lower surface side, and one end of the bent product By forming a pressing punch from the lower surface side on the connecting wall to plastically deform it, a valve stem guide groove for accommodating the tip of the valve stem is formed, and at the same time, the bottom surface of the valve stem guide groove is formed into a predetermined curved surface. and a step of viewing including, the width of the pressing punch "W", the inside space of the two side walls
When “S” is set, the dimensions are set so that the relational expression W ≧ S holds.
The rocker arm manufacturing method that has been set .