JP2000240410A - Rocker arm body using pressing product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive rocker arm body using a pressed product capable of preventing a rocker arm from being released from a valve. SOLUTION: A rocker arm is guided at a top portion 10 of a valve stem 9 fitted to a grooved portion 2b opened downward, thereby preventing the rocker arm from being released from a valve. A top wall 15 of the grooved portion 2b is folded by press molding which using an axial line parallel to a strut of a roller in slide contact with a cam as a starting line. A fabricating cost can be reduced in comparison with the case where a separate part is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm body used for a valve train of an internal combustion engine and transmitting cam drive to a valve.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a reduction in the inertial weight of a valve train of an internal combustion engine. Therefore, it has been desired to reduce the weight of a rocker arm. In such a case, it is difficult to make an optimal design such as a thin curved shape in order to achieve weight reduction, and there is a problem that it is difficult to reduce the weight. Further, post-processing after forming by forging or casting is complicated, and there is a problem that the manufacturing cost is high.

Therefore, it has been proposed to manufacture the main body of the rocker arm by press molding. Generally, ductile materials such as mild steel and aluminum alloys used for press forming do not break by compression, so there is no need to consider the breakage by compression. Therefore, in terms of strength, it is customary to form a groove having a pair of side walls on the compression side of bending, that is, to form a groove that opens upward.

The reason why the groove is opened upward is that there is a need to avoid interference with a lash adjuster for adjusting valve clearance which abuts one end of the rocker arm body from below. . On the other hand, referring to FIG. 12, the other end of the rocker arm main body 91 having the groove shape opened upward as described above has a valve stem 92 (referred to as a rod-shaped portion of the valve) from below.
However, since the rocker arm is not guided left and right by the top of the valve stem 92, the behavior of the rocker arm becomes unstable, and the rocker arm may come off from the valve stem 92.

Therefore, a two-piece structure in which the part for receiving the valve is formed of a separate part and joined to the remaining part is conceivable. However, the number of parts increases and the number of joining steps increases. In addition, it is difficult to secure the dimensional accuracy of the finished product because different parts are combined. The present invention has been made in view of the above problems, and an object of the present invention is to provide an inexpensive rocker arm main body using a press-formed product that can stably guide a valve stem.

[0006]

Means for Solving the Problems As means for solving the problems to achieve the above object, the aspect of the invention described in claim 1 is as follows.
The folded piece formed by press-forming with the axis parallel to the support shaft of the roller that slides on the cam as the starting line forms the top wall of the channel-shaped portion that opens downward to receive the valve stem. It is characterized by the following.

In this aspect, the rocker arm can be received while guiding the rocker arm to the left and right at the top of the valve stem that fits into the groove that opens downward, and the rocker arm can be prevented from coming off. Moreover, since the top wall is formed by folding back by press molding, the number of components and the number of joining steps can be reduced and the manufacturing cost can be reduced as compared with the conventional case using separate components.

According to a second aspect of the present invention, in the first aspect, the groove portion includes a pair of opposed bent pieces bent on both sides of the top wall by press molding. Things. In this embodiment, by forming a pair of bent pieces in advance on both sides of the top wall portion and forming an intermediate body having a channel portion that opens upward, the channel portion that opens upward is folded back. , A channel opening downward can be obtained. It is possible to improve the dimensional accuracy of the groove.

According to the third aspect of the present invention, in the first aspect,
Wherein the folded piece is received by the lower surfaces of a pair of inward flanges respectively continuous with lower ends of a pair of opposed side walls having an insertion hole through which the support shaft of the roller is inserted. . In this embodiment,
Since the folded piece is received by the pair of flanges, the deformation strength of the groove portion can be increased. The folded piece constituting the top wall may be welded to the pair of flanges, and in this case, the deformation of the groove due to the springback of the folded piece can be reliably prevented.

According to a fourth aspect of the present invention, in the first aspect, the top wall is folded between a pair of opposed side walls having an insertion hole through which a support shaft of the roller is inserted. The lower end is received by a pair of inward flanges that are respectively continuous with the lower end, and the groove portion is constituted by the top wall and the pair of inward flanges.

In this aspect, since the top wall folded between the pair of side walls is received by the pair of inward flanges, the strength of the groove portion can be increased. Since the pair of inward flanges are used as they are as the side walls of the channel, the manufacturing cost can be further reduced. In addition, the folded top wall may be subjected to the projection welding to the pair of inward flanges, and in this case, the deformation strength of the groove portion can be further increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a mounted state of a rocker arm according to a first embodiment of the present invention. With reference to FIG. 1, the rocker arm 1 is a cam follower type rocker arm, which is attached to a rocker arm main body 2 via a support shaft 3 at the center of the rocker arm main body 2 and engages with a cam 20. And a roller 4. The rocker arm body 2 has first and second ends 5,6. The first end 5 is received on a lifter post 8 as a fulcrum extending upward from a cylinder head 7 of the internal combustion engine. The second end 6 is a valve stem 9
Is engaged with the upper end 10.

In FIG. 1, reference numeral 16 denotes a compression coil spring that urges the valve stem 9 in a lifting direction (that is, a direction in which the valve is opened), and 17 denotes a retainer spring that holds the compression coil spring 16. Referring to FIG. 2 which is a perspective view of the rocker arm,
Has a main body 2a including a first end 5 and having a groove shape that opens upward. Rocker arm body 2
The second end 6 is provided with a downwardly open channel 2b.

The rocker arm main body 2 has first and second side wall portions 11 and 12 which face each other and have insertion holes 14 through which both ends of the support shaft 3 of the roller 4 are inserted.
In a part of the main body portion 2a, the first and second side wall portions 11, 1
The lower edges of the two are connected by the bottom wall portion 13 to form a groove opening upward and the overall strength is secured. In addition, a part of the main body 2a is opened both up and down,
Exposure of the roller 4 up and down is allowed. Numeral 34 is a cylindrical projection formed of a deep drawing portion formed on the bottom wall portion 13 for receiving the lifter post 8.

Referring to FIG. 4, channel 2b is open downwardly to receive valve stem 9, and channel 2b
The top wall 15 has an axis 33, which will be described later, parallel to the support shaft 3 of the roller 4 that slides on the overhead cam 20 as a starting line.
Folded piece 22 formed by press forming
It consists of. With reference to FIGS. 3 and 4, on both sides of the folded piece 22 constituting the ceiling wall 15,
A pair of opposing bent pieces 23, 23 bent by press molding are formed, and the folded piece 22 and the pair of bent pieces 23, 23 form a channel 2 b.

The folded piece 22 constituting the top wall 14 is received by the lower surfaces 25 (see FIG. 3) of a pair of inward flanges 24, 24 which are respectively connected to the lower ends of the first and second side walls 11, 12. ing. In FIG. 4, reference numeral 26 denotes a U-shaped bent portion that connects one end of each inward flange 24 to the folded piece 22. Referring to FIG. 3, the upper end 10 of the valve stem 9 is introduced into the groove 2 b, is received by the top wall 15, and is restricted from moving in the left-right direction by the left and right bent pieces 23, 23. Valve stem 9
Extends upward from the cylinder head 7 through the compression coil spring 16. This compression coil spring 16
In a state surrounding the valve stem 9, the cylinder stem 7 is in contact with the annular retainer spring 17 attached to the valve stem 9. Retainer spring 17
A pair of cotter pins 19 fitted in a circumferential groove 18 of the valve stem 9 are engaged in a wedge shape on the inner peripheral portion of the valve stem 9.

Referring again to FIG. 1, when the overhead cam 20 engaged with the roller 4 rotates, the rocker arm 1 is swung to move the valve stem 9 below the valve stem 9 when the valve stem 9 moves in the longitudinal direction. An end valve (not shown) opens and closes. The lifter post 8 is constituted by a plunger of a hydraulic lash adjuster. The lash adjuster automatically adjusts the valve clearance by the action of internal oil. When the valve opens, the oil inside acts to prevent the plunger from lowering. When the valve closes, the plunger rises by a small amount due to the function of the internal return spong (not shown), and the valve clearance becomes zero.

The rocker arm body 2 is obtained by stamping and forming a sheet metal by press molding, as shown in FIGS.
It is formed using an intermediate A as shown in (a). That is, as shown in FIG. 5A and FIG. 6A, the intermediate body A is formed by bending inward flanges 24 at the lower ends of the first and second side walls 11 and 12 at right angles. In this state, connecting pieces 27, 27 as first portions extending from one end of each flange 24 on the same plane of each flange 24.
And the tips of the connecting pieces 27, 27 are connected to each other via a connecting portion 28 as a second portion parallel to the support shaft 3 of the roller 4. The ceiling wall 1 is connected to the connecting portion 28.
5 is provided.
Between the connecting portion 28 and the third portion 29, a pair of cuts 30 having a predetermined depth are formed at positions facing each other.

The third portion 2 is formed by using each of the cuts 30.
9 is bent at right angles about an axis 31 perpendicular to the support shaft 3 of the roller 4 to form an intermediate portion having a groove 32 that opens upward as shown in FIGS. 5 (b) and 6 (b). Form body B. Next, an axis 3 extending through the connecting pieces 27 of the intermediate body B and extending in a direction parallel to the support shaft 3 of the roller 4.
The third portion 29 is turned 180 degrees around 3 to form a downwardly open channel 2b as shown in FIGS. 4 and 6C. At this time, the central portions of the connecting pieces 27, 27 are folded back to form bent portions 26. Also, a channel 2 that opens downward
The folded piece 22 that is the top wall 15 b abuts on the lower surfaces 25 of the inward flanges 24, 24. Thereby, the rocker arm main body 2 is completed.

In the present embodiment, the rocker arm can be received while guiding the rocker arm to the left and right at the top 10 of the valve stem 9 fitted in the groove 2b which opens downward, thereby preventing the rocker arm from coming off the valve. can do. Moreover, since the top wall 15 is obtained by folding back by press molding, the number of parts and the number of joining steps can be reduced and the manufacturing cost can be reduced as compared with the conventional case using separate parts.

Further, a pair of bent pieces 23, 23 are formed on both sides of the third portion 29 serving as the top wall 15 in advance to form an intermediate body B having a groove-shaped portion 32 that opens upward. By folding back the upwardly opening channel portion 32 of the intermediate body B, the downwardly opening channel portion 2b can be obtained. Since the upwardly directed groove 32 can be formed by one press die, the dimensional accuracy of the groove 2b can be improved.

Further, since the folded piece 22 serving as the top wall 15 is received by the pair of inward flanges 24, 24, the deformation strength of the groove 2b can be increased. Further, the width between the bent pieces 23 can be freely set in accordance with the top 10 of the valve stem 9. Then, FIG.
FIG. 11 shows a second embodiment of the present invention. FIG.
Referring to FIG. 5, the second embodiment is different from the first embodiment in FIG. 1 in that a channel 2c is formed instead of the channel 2b. 8 and 9, the channel 2
The top wall 35c is composed of a folded piece 36 folded between the first and second side walls 11 and 12, and a pair of folded pieces 36 connected to the lower ends of the first and second side walls 11 and 12, respectively. The pair of inward flanges 2 are received by the upper surfaces 37 of the inward flanges 24, 24.
4, 24 and the top wall 35 constitute the channel 2c.

The rocker arm body 2 is obtained by stamping a sheet metal by press molding, as shown in FIGS.
It is formed using an intermediate C as shown in (a). That is, as shown in FIG. 10 and FIG. 11A, each of the intermediate bodies C is formed by bending inward flanges 24 at the lower ends of the first and second side walls 11 and 12, respectively. And connecting portions 27, 27 as first portions extending on the same plane of each flange 24 from one end of the connecting portion 27, and a second portion 38 for forming the ceiling wall 35 at the tip of the connecting portions 27, 27. Is extended.

Next, through each connecting piece 27, 27,
With the axis 39 extending in the direction parallel to the support shaft 3 of the roller 4 as a starting line, the second portion 38 is turned upward by 180 °, and FIG.
A downwardly opening channel 2c as shown in FIG. 1 (b) is formed. At this time, the central portions of the connecting pieces 27, 27 are folded back to form bent portions 26. In addition, the folded piece 36 which is the top wall 35 of the channel portion 2b that opens downward is
4 and 24 are in contact with the upper surface 37. Thereby, the rocker arm main body 2 is completed.

In the present embodiment, the second portion 38 is folded back between the pair of side walls 11 and 12 to form the top wall 35, and the pair of inward flanges 24 and 24 are used as they are as the side walls of the channel 2c. In addition, the manufacturing cost can be reduced. The top wall 35 is connected to the pair of inward flanges 24,
24, the strength of the channel 2c can be increased.

The present invention is not limited to the above embodiments, but the top walls 15 and 35 made of folded pieces.
To the side walls 11 and 12 or the inward flange 2
4 and 24 by projection welding.
The deformation strength of c may be increased. In addition, various changes can be made within the scope of the present invention.

[0027]

According to the first aspect of the present invention, the rocker arm can be received while guiding the rocker arm to the left and right at the top of the valve stem that fits into the groove that opens downward, thereby preventing the rocker arm from coming off. Can be. Moreover, since the top wall is obtained by folding back by press molding,
Compared with the conventional method using a separate part, the number of parts and the number of joining steps can be reduced, and the manufacturing cost can be reduced.

According to the second aspect of the present invention, a pair of bent pieces are formed on both sides of a portion serving as a ceiling wall, and an intermediate body having a groove opening upwardly is formed in advance. By folding the upwardly open channel, a downwardly open channel can be obtained. The dimensional accuracy of the channel can be improved. According to the third aspect of the present invention, since the folded piece is received by the pair of flanges, the deformation strength of the groove portion can be increased.

According to the fourth aspect of the present invention, since the top wall folded between the pair of side walls is received by the pair of inward flanges, the strength of the groove portion can be increased. Since the pair of inward flanges are used as they are as the side walls of the channel, the manufacturing cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a mounted state of a rocker arm according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a rocker arm.

FIG. 3 is a sectional view of a main part of a valve stem and a rocker arm.

FIG. 4 is a perspective view of a main part of the rocker arm main body.

FIGS. 5A and 5B are perspective views sequentially showing a manufacturing process of the rocker arm main body.

FIGS. 6 (a), (b) and (c) are perspective views sequentially showing the steps of manufacturing the rocker arm main body.

FIG. 7 is a schematic diagram illustrating a state of attachment of a rocker arm according to a second embodiment of the present invention.

FIG. 8 is a perspective view of a rocker arm.

FIG. 9 is a sectional view of a main part of the valve stem and the rocker arm.

FIG. 10 is a perspective view showing one step of manufacturing the rocker arm main body.

FIGS. 11A and 11B are perspective views sequentially showing a manufacturing process of the rocker arm main body.

FIG. 12 is a front view of a portion for receiving a valve stem of a conventional rocker arm main body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rocker arm 2 Rocker arm main body 2b, 2c Channel-shaped part 3 Support shaft 4 Roller 5 1st end part 6 2nd end part 9 Valve stem 10 Upper end 11 1st side wall part 12 2nd side wall part 15 Top wall 22 Folded Piece 23 Folded Piece 24 Inward Flange 25 Lower Surface 31 Axis 32 Groove 33 Axis 35 Top Wall 36 Folded Piece 37 Upper Surface 39 Axis

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuyuki Kotani 3-5-8 Minamisenba, Chuo-ku, Osaka Koyo Seiko Co., Ltd. F-term (reference) 3G016 AA06 AA19 BB18 BB22 CA13 CA27 CA41 CA44 DA20 FA07 GA00

Claims (4)

[Claims] 1. A folded wall formed by press forming with an axis line parallel to a support shaft of a roller that slides on a cam as a starting line, a top wall of a groove-shaped portion that opens downward to receive a valve stem. A rocker arm body using a press-formed product characterized by comprising. 2. A rocker arm body using a press-formed product according to claim 1, wherein said groove-shaped portion includes a pair of opposing bent pieces bent on both sides of said top wall by press forming. . 3. The method according to claim 1, wherein the folded pieces are received by lower surfaces of a pair of inward flanges respectively connected to lower ends of a pair of opposed side walls having an insertion hole through which a shaft of the roller is inserted. The rocker arm body according to claim 1. 4. The top wall is folded back between a pair of opposed side walls having an insertion hole through which the support shaft of the roller is inserted, and is formed by upper surfaces of a pair of inward flanges respectively connected to lower ends of the pair of side walls. The rocker arm body using a press-formed product according to claim 1, wherein the groove-shaped portion is formed by the top wall and the pair of inward flanges.