JP3497374B2 - 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. 9 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. 9 and 10.
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. And one end connecting wall configured to be contacted with each other, and pressing processing is performed on both side regions of the one end connecting wall from an upper surface side, and a pair of convex strips is formed on both lower surface sides of the one end connecting wall. There is formed in a downward projecting shape, between the pair of convex portions, the valve stem guide groove is formed Rutotomoni to guide wall the ridge, of the side walls and the end connecting wall
The area around the pressure groove at the corner is buckled and deformed,
The gist of the present invention is that one side surface is in close contact with the bottom surface of the pressing groove .

In the rocker arm of the first aspect of the present invention, a pair of projecting ridges is formed on both sides of the lower surface of the one end connecting wall so as to project downward by the protrusion pressing process, and between the ridges, Since the valve stem guide groove is formed by using the ridge portion as the guide wall, for example, compared with the case where the guide groove is formed by using low-efficiency machining such as forging or precision casting,
The valve stem guide groove can be formed easily and accurately.

Further, in the first aspect of the present invention, the periphery of the pressing groove
Buckle and deform one side of the pressing groove to the bottom surface.
Therefore, the joints between both side walls and the one end connecting wall have sufficient rigidity.
The rocker arm itself.
The rigidity of can be improved.

On the other hand, according to the second aspect of the present invention, a step of obtaining a metal plate-shaped processed product having a predetermined shape, and bending the plate-shaped processed product to form a pair of both side walls and both side walls thereof. A method of manufacturing a rocker arm, comprising the step of obtaining a bent product having one end connecting wall configured to connect the one end portions to each other and a valve stem tip contacting the lower surface side, Before the bending process, a pressing process is performed from the upper surface side on both sides of the region corresponding to the one end connecting wall in the plate-shaped product, and a pair of convex strips is formed on both lower surface sides of the corresponding region. The gist of the present invention is that the valve stem guide groove is formed between the pair of convex ridges and has the convex ridges as guide walls.

The rocker arm manufacturing method of the second aspect of the present invention specifies one form of the manufacturing process of the rocker arm of the first aspect of the present invention. Particularly, in the present manufacturing method, at the stage of a plate-shaped processed product. Since the guide wall is formed by the protrusion pressing process, it is possible to perform the process more easily and accurately as compared with the case where the pressing process is performed after the bending process, for example.

In the second aspect of the invention, the plate-shaped product is bent by using the pressing groove provided on the upper surface side of the plate-shaped product as a bending portion to form the bent product. On the other hand, it is preferable to adopt a configuration in which one side surface of the pressing groove is brought into close contact with the bottom surface of the pressing groove by press-forming both side walls of the bent processed product toward the one end connecting wall side.

That is, when this structure is adopted, sufficient rigidity can be secured in the connecting portion between both side walls and the one end connecting wall.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A rocker arm that is an embodiment of the present invention will be described in detail below 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, "Upper side" of the drawing according to actual usage
Will be described as "lower side".

The rocker arm (20) of the present invention is shown in FIG.
A pair of opposite side walls (22), as shown in FIG.
And 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. Further, on the lower surface (32) of the one end connecting wall (30), a valve stem guide groove (40) having a pair of projecting ridges (41a) provided on both sides thereof as a guide wall (41) is formed. At the center of the lower surface side of the other end connecting wall (23), the pivot engaging recess (2
4) is formed. Further, shaft fixing holes (21) whose axial centers coincide with each other are formed in the longitudinal middle portions of the side walls (22).

In order to manufacture this rocker arm (20), first, as shown in FIG. 1, a predetermined area of a steel plate is punched out to obtain a punching plate of a substantially rectangular shape having arcuate convex portions on both side edges, The center of the punched plate is punched to obtain a blank processed product (20a) having a drum-shaped hole.

Next, a hemispherical pivot engagement recess (24) is formed in the region corresponding to the center of the lower surface of the other end connecting wall (23) of the blank processed product (20a) by overhanging.

Subsequently, as shown in FIGS. 2 and 5, the one end connecting wall (3) in the blank processed product (20a).
Pressing is performed on both sides of the region (30a) corresponding to 0) so that a pressing punch (not shown) is driven from the upper surface side. As a result, both sides of the corresponding area (30a) are plastically deformed so that the material inside the corresponding area (30a) moves downward, and a pair of pressing grooves (45) are formed on both sides of the upper surface of the corresponding area (30a).
At the same time that the ridges are formed, a pair of ridge portions (41a) are formed in a downward protruding shape on both sides of the lower surface side of the corresponding area (30a). In this way, between the pair of ridges (41a) on the lower surface side of the corresponding area (30a), the ridges (41a) serve as guide walls (41), and the lower surface (32) of the corresponding area (30a) forms the bottom surface (valve). A valve stem guide groove (40) serving as a stem contact surface) is formed.

Here, in this embodiment, as shown in FIG. 5, the pressing groove (45) has a bottom surface (45) on the opening side.
Both side surfaces (45a) are formed as inclined surfaces having a predetermined angle (θ) with respect to the pressing direction line (P) so as to be larger than b). As a result, it is possible to prevent the pressing punch from sticking to the blank processed product (20a) during the pressing process, and it is possible to smoothly perform continuous processing.

Next, as shown in FIGS. 3 and 6, the blank processed product (20a) is folded at the corner portions of the side surface (45a) and the bottom surface (45b) located on the outer side of the pair of pressing grooves (45). The bending process is performed as a bending line.

As a result, the one end lower end and the other end lower end of the both side walls (22) are connected by the one end connecting wall (30) and the other end connecting wall (23), and between the pair of both side walls (22). A U-shaped bent product (20b) in end view is obtained which has an opening for accommodating and allowing the roller to be seen between the one end connecting wall (30) and the other end connecting wall (23). Needless to say, the valve stem guide groove (40) is arranged on the lower surface side of the one end coupling wall (30) in the bent product (20b), and the pivot engagement recess (23) is
It is arranged on the lower surface side of the other end connecting wall (23).

Next, as shown in FIG. 7, a bent product (20
Both side walls (22) on one end side of b) are pressure-molded toward the lower side to form both side walls (22) and one end connecting wall (30).
The inner corner, that is, the periphery of the pressing groove (45) is subjected to buckling deformation so that the side surface (45a) located outside the pressing groove (45) is brought into close contact with the bottom surface (45b) of the pressing groove (45). Note that, in FIG. 7, for reference, the state of both side walls (22) of the bent product (20b) before pressure forming is shown by a broken line.

Next, as shown in FIG. 4, for example, both side walls (2
A punch for punching holes is punched from both sides in the middle portion in the lengthwise direction of 2) to form shaft fixing holes (21) whose axial centers coincide with each other at predetermined positions on both side walls (22).

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

According to the manufacturing method of this embodiment, the rocker arm (2) is formed only by press working such as outer diameter punching, pressing, bending, pressing and punching.
Since 0) is manufactured, it is possible to improve production efficiency and reduce costs without requiring low-efficiency machining such as forging and precision casting.

Further, since the guide wall (41) is formed by projecting and pressing at the stage of the plate-shaped blank processed product (20a), compared with the case where pressing is performed after bending, for example. Further, the machining can be performed easily and accurately, the positional accuracy and the dimensional accuracy of the guide wall (41) and the guide groove (40) can be improved, and the productivity can be further improved.

Further, in the present embodiment, both side walls (22) of the bent product (20b) are pressure-molded, and the periphery of the pressing groove (45) is buckled and deformed so that one of the pressing grooves (45) is deformed. Since the side surface (45a) is in close contact with the bottom surface (45b),
Sufficient rigidity can be ensured in the connecting portion between the side walls (22) and the one end connecting wall (30), and thus the rigidity of the rocker arm itself can be improved.

[0030]

As described above, according to the rocker arm of the first aspect of the present invention, a pair of projecting ridges are formed on both sides of the lower surface of the one end connecting wall by projecting and pressing to project downward. Since the valve stem guide groove having the ridge portion as the guide wall is formed between the ridge portions, for example, when the guide groove is formed by using low efficiency machining such as forging or precision casting. As compared with the above, the valve stem guide groove can be formed easily and accurately, so that the guide groove having high positional accuracy and dimensional accuracy can be formed, and production efficiency can be improved and cost can be reduced . Buckling around the pressing groove
Shaped so that one side of the pressing groove is in close contact with the bottom.
Therefore, ensure sufficient rigidity for the joints between both side walls and one end joint wall.
Can be kept, and thus the rigidity of the rocker arm itself
There is an effect that can improve .

On the other hand, the rocker arm manufacturing method of the second aspect of the present invention specifies one form of the manufacturing process of the rocker arm of the first aspect of the present invention, and therefore, a rocker arm having the above-described effects is produced. You can In particular, in this manufacturing method, since the guide wall is formed by projecting and pressing at the stage of a plate-shaped product, it is much simpler than, for example, the case where pressing is performed after bending. And can be processed accurately, guide wall,
That is, there is an effect that the positional accuracy and the dimensional accuracy of the valve stem guide groove can be further improved and the productivity can be further improved.

Further, in the second invention, when one side surface of the pressing groove is brought into close contact with the bottom surface by pressure forming both side walls of the bent product, the connecting portion between both side walls and one end connecting wall is formed. There is an advantage that sufficient rigidity can be ensured and the rigidity of the rocker arm itself can be improved.

[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 blank processed product after a protrusion pressing process in the manufacturing method of the embodiment.

FIG. 3 is a perspective view showing a bent 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 a blank processed product of the embodiment after a protrusion is pressed.

FIG. 6 is a cross-sectional view showing a bent product of the embodiment.

FIG. 7 is a cross-sectional view showing the bent product of the embodiment after pressure molding.

FIG. 8 is a cross-sectional view showing a rocker arm of the embodiment.

FIG. 9 is a sectional view showing a valve mechanism of an internal combustion engine in a conventional vehicle.

FIG. 10 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 30a ... Corresponding area 40 ... Valve stem guide groove 41 ... Guiding wall 41a ... ridge 45 ... Press groove 45a ... side surface 45b ... bottom surface

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 5-106409 (JP, A) JP 5-86819 (JP, A) JP 5-272310 (JP, A) JP 2- 6034 (JP, A) (58) Fields investigated (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 Both side areas of the ridge are pressed from the upper surface side, and a pair of convex ridges are formed in a downward projecting shape on both sides of the lower surface side of the one end coupling wall. When the valve stem guide groove and guide wall is Ru is formed
Both of the pressing grooves are formed in the inner corners of the both side walls and the one end connecting wall.
The periphery is buckled and the one side surface of the pressing groove is
A rocker arm that is closely attached to the bottom of the pressure groove . 2. A step of obtaining a metal plate-shaped product having a predetermined shape, bending the plate-shaped product to connect a pair of both side walls and one end of the both side walls, And a step of obtaining a bent product having a one-end connecting wall configured such that the tip of the valve stem is brought into contact with the lower surface side, the rocker arm manufacturing method comprising: The press-work is applied from the upper surface side to both sides of the region corresponding to the one end connecting wall in the plate-shaped processed product, and a pair of ridges is formed to project downward on both sides of the lower surface side of the corresponding region. , Between the pair of ridges,
A method for manufacturing a rocker arm, characterized in that a valve stem guide groove having the ridge as a guide wall is formed. 3. The plate-shaped product is bent by using a pressing groove provided on the upper surface side of the plate-shaped product as a bending portion to form the bent product, while the bending process is performed. The rocker arm manufacturing method according to claim 2, wherein one side surface of the pressing groove is brought into close contact with the bottom surface of the pressing groove by press-molding both side walls of the product toward the one end connecting wall side.