JP2003001361A - Rocker arm manufacturing method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To secure a required dimensional accuracy, form a housing for accommodating a roller with high productivity and at low cost, and increase the rigidity of a wall forming the housing. Reduce the size and weight of rocker arms. SOLUTION: The rocker arm of the valve train for an internal combustion engine including a housing portion for accommodating a roller contacting a cam is manufactured by a working process including a cold forging process. The cold forging step includes a first step of forming a second material 42 by performing sizing by die forging on a first material 40 having a prepared hole 41, and forming a punch 64 in a prepared hole 41 of the second material 42. At the same time as forming a through-hole forming the housing portion by performing sizing processing by punching, the punch 64 during punching exerts pressure on the molding material to completely seal the second material 42. And a finishing step of forming the rocker arm material 43 by performing die forging in the above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a rocker arm that constitutes a valve operating system of an internal combustion engine, the rocker arm having a housing for housing a roller that makes rolling contact with a rotating cam.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a rocker arm which constitutes a valve train of an internal combustion engine and which has a roller in rolling contact with a cam, a housing portion of the roller is formed as follows. That is, in the case where the rocker arm is formed by forging, the accommodating portion is formed by cutting, and as disclosed in Japanese Patent Laid-Open No. 11-13443, the rocker arm is formed by injection molding metal powder and then sintering. In the case of molding by (1), the accommodating portion was formed at the same time when the rocker arm was molded.

[0003]

By the way, forming the accommodating portion of the roller by cutting has a problem that productivity is low and cost is high because the processing requires time. Further, a rocker arm made of a sintered metal is difficult to obtain good dimensional accuracy because it shrinks during sintering, and since it has a void, it generally has low rigidity, and it is necessary to secure the required dimensional accuracy and rigidity. Further, additional processing and treatment such as cold working and heat treatment are required, which again has the drawback of low productivity and high cost.

Further, since the wall forming the accommodating portion supports the roller contacting the cam and is adjacent to the swinging base portion through which the rocker shaft is inserted, it is a portion requiring rigidity, but In order to secure the required rigidity in the vicinity of the housing, it is necessary to increase the size of the wall,
Sometimes the rocker arm became large and its weight increased.

The present invention has been made in view of such circumstances, and the inventions according to claims 1 to 5 are:
The accommodating part for accommodating the rollers is formed with high productivity and low cost while ensuring the required dimensional accuracy.
It is an object of the present invention to reduce the size and weight of a rocker arm in which the rigidity of the wall forming the housing is increased. And claim 5
It is another object of the invention described above to improve the retaining capacity of the lubricating oil in the accommodating portion of the roller.

[0006]

According to a first aspect of the present invention, there is provided a pair of rollers for accommodating a roller in rolling contact with a rotating cam and supporting a roller shaft for rotatably supporting the roller. A rocker shaft having an accommodating portion formed by a wall including a support wall and a swing base portion that is radially adjacent to a first radial wall that is the wall of the accommodating portion, and is inserted into the swing base portion. A rocker arm of an internal combustion engine valve operating device that is swingably supported by the cam and that defines a swinging motion that opens and closes an engine valve by a working process including a cold forging process that molds the swinging base. In the method of manufacturing a rocker arm to be manufactured, the cold forging step includes a first forging step of forming a second material by subjecting a first material having a pilot hole to a sizing process by die forging except for the pilot hole, The second
With the sizing part of the material closely fitted to the mold,
The prepared hole is subjected to sizing processing by punching with a punch that is a component of the forming die to form a through hole for forming the accommodation portion, and at the same time, the punch being punched is By forcing the wall forming the pilot hole to exert a pressure on the molding material of the second material, the second material is die-forged by the molding die in a completely sealed state at the end of the punching process. And a finish forging step of forming a rocker arm material which is a finished member by cold forging of the rocker arm.

According to the first aspect of the present invention, in the finish forging step, the accommodating portion of the roller is formed by sizing by punching with a punch inserted in the pilot hole, and the punching process is performed. When punching,
By pressing from the punching direction to a direction orthogonal to the punching direction and applying a pressure to the molding material, the molding material is compressed and flows, so that the pair of support walls and the first diameter forming the accommodating portion are formed. On the walls including the direction walls, a work-hardened layer is formed and the crystal structure of the molding material becomes dense in the pressing direction, so that the rigidity increases, and at the end of the punching process, a completely closed state is obtained. By the die forging, the sizing process is performed even when the second material has a portion that has not been sized in the first forging process, and the finished member by cold forging including the through hole and the swing base of the rocker arm. The rocker arm material that is is molded.

As a result, the following effects are obtained. That is, since the accommodation portion of the roller is formed by utilizing the through hole formed by punching with the punch in the step of finish cold forging, the accommodation portion can be secured with a required dimensional accuracy. It can be formed with high productivity and at low cost. Moreover, the pair of support walls forming the accommodation portion and the first
The wall including the radial wall has a high rigidity because a work-hardened layer is formed by pressing with a punch and a region becomes dense in the direction in which the crystalline structure of the molding material is pressed. Therefore, the rigidity of the pair of support walls supporting the roller shaft and the rigidity of the first radial wall adjacent to the swing base are increased, and the required rigidity can be ensured and the rocker arm can be made smaller and lighter.

According to a second aspect of the present invention, in the rocker arm manufacturing method according to the first aspect, the rocker arm comprises:
A peripheral portion of the opening of the accommodating portion has a receiving portion with which a lost motion mechanism that biases the rocker arm toward the cam abuts, and the receiving portion has an opening on the end side of the punching process in the through hole. The cold forging step is formed on the peripheral portion of the portion.

According to the second aspect of the present invention, at the time of punching, in the portion of the wall of the through hole on the end side of punching, the flow of the molding material by pressing with the punch is caused by the molding die. Since it is blocked, the crystal structure of the molding material pressed by the punch becomes dense also in the punching direction of the punch, so that the end side portion has a high rigidity. As a result, in addition to the effect of the invention described in claim 1, the following effect is exhibited. That is, in the wall of the accommodating portion, since the receiving portion on which the biasing force of the lost motion mechanism acts is formed at the edge of the opening portion on the end side of the punching process of the accommodating portion, which has a high rigidity, has a required rigidity The receiving portion can be formed without increasing the size, and the rocker arm can be reduced in size and weight.

According to a third aspect of the present invention, in the method of manufacturing a rocker arm according to the first aspect, the accommodating portion is formed by the through hole itself, and the rocker arm is provided with an abutting portion that abuts against the engine valve. An operating part, the operating part being radially adjacent to the second radial wall facing the first radial wall with the through hole interposed therebetween, and being formed in the cold forging step Is.

According to the invention of claim 3, in addition to the effect of the invention of claim 1, the following effect is exhibited. That is, since the work hardening and the crystallographic structure of the molding material are dense in the pressing direction, the rigidity of the second radial wall adjacent to the actuating portion, which is the wall forming the housing portion, increases. The rigidity with respect to the load from the engine valve that acts on the actuating portion is increased, and the rocker arm can be reduced in size and weight while ensuring the required rigidity.

According to a fourth aspect of the present invention, in the rocker arm manufacturing method according to the third aspect, the punch is inserted from an opening of the prepared hole on the cam side.

According to the invention described in claim 4, for the same reason as described in claim 2, the end side portion of the wall forming the accommodating portion is a portion having high rigidity.
As a result, in addition to the effect of the invention described in claim 3, the following effect is exhibited. That is, since the end side of the wall of the accommodating portion has a large rigidity, the rigidity against the load struck by the cam acting on the rocker arm via the roller rollingly contacting the cam is increased, and the required rigidity is secured. In addition, the rocker arm can be made smaller and lighter.

According to a fifth aspect of the present invention, in the rocker arm manufacturing method according to any one of the first to fourth aspects, the wall surfaces of the pair of support walls are between the roller and the roller. Form a small gap in the axial direction that can slide, and the opening on the end side of the punching process of the through hole,
It is located below the rocker arm.

According to the invention described in claim 5, for the same reason as described in claim 2, the end of the wall forming the accommodating portion in which the crystal structure of the molding material pressed by the punch becomes particularly dense. In the side portion, since a slight springback occurs after the through hole is formed, the springback further reduces the slight axial gap between the pair of support walls and the roller. As a result, in addition to the effect of the invention described in claim 1, the following effect is exhibited. That is, in the end portion of the pair of support walls, the slight axial gap between the pair of support walls and the roller becomes slightly narrower, and the end portion is located below the rocker arm. Since it is located, the lubricating oil holding capacity in the gap is improved, and the retained lubricating oil improves the lubricity of each sliding part that slides due to the rotation of the roller, thus improving the durability of the roller and the rocker arm. To do. Moreover, since the structure for improving this holding ability is obtained by forming with a punch,
Its formation is easy.

In this specification, the axial direction means the direction of the rotation axis of the roller, and the radial direction means the radial direction extending from the rotation axis of the roller.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 to 14 show the first embodiment of the present invention.
In the first embodiment, an internal combustion engine is
An intake port and an exhaust port are provided in a cylinder head that is a DOHC-type multi-cylinder four-cycle internal combustion engine mounted on a vehicle and that is coupled to a cylinder block into which a piston is reciprocally fitted. Then, one intake port is provided for each cylinder in the valve operating chamber formed by the cylinder head and the cylinder head cover connected to the upper surface thereof.
An intake valve 1 that is a pair of engine valves that open and close a pair of intake valve openings, and an exhaust valve (not shown) that is a pair of engine valves that open and close a pair of exhaust valve openings of an exhaust port are provided. The intake valves 1 are opened / closed by an intake valve operating device V1 including an intake cam shaft 2, and the exhaust valves are opened / closed by an exhaust valve operating device including an exhaust cam shaft.

The intake side valve operating device V1 corresponding to one cylinder will be described in detail below, but the exhaust side valve operating device also has the same structure as the intake side valve operating device V1. Referring to FIGS. 1 and 2, the valve stem 1a of each intake valve 1 is slidably fitted to the valve guide 3 press-fitted into the cylinder head, and the valve stem 1a
The intake valve 1 is urged to close the intake valve opening by a valve spring 5 provided between the retainer 4 and the cylinder head, which are coupled to each other.

In the intake side valve operating device V1, the power of the crankshaft which is rotationally driven by the piston is transmitted via a transmission mechanism such as a timing belt and is rotationally driven at a rotational speed of 1/2 of the crankshaft. The intake camshaft 2 and the first and second rocker arms 6 for opening and closing the pair of intake valves 1, respectively.
7, a rocker shaft 8 having a central axis L1 parallel to the rotation axis of the intake camshaft 2 and fixed to the cylinder head and supporting both rocker arms 6 and 7 in a swingable manner, and both rocker arms 6 and 7. And a connection switching mechanism C1 for switching connection and disconnection between them.

On the intake camshaft 2, a first cam 9 for defining the swinging motion of a first rocker arm 6 for opening and closing one intake valve 1 and a swinging of a second rocker arm 7 for opening and closing the other intake valve 1. A second cam 10 is formed which defines the movement. The first cam 9 has a profile that opens and closes the intake valve 1 with a predetermined operating angle and a predetermined lift amount.
The cam 10 has a profile that keeps the other intake valve 1 closed or a valve that opens slightly but remains substantially at rest.

Swiveling bases 6a and 7a having insertion holes 6b and 7b, respectively, through which the rocker shaft 8 is inserted, are provided at one ends of the first and second rocker arms 6 and 7, respectively. 7 is swingably supported on the rocker shaft 8 by the swing bases 6a and 7a, and is further adjacent to the central axis L1 (or swing axis) of the rocker shaft 8 (also the axial direction A1). Will be placed. Further, the other end of each of the first and second rocker arms 6 and 7 is screwed into a screw hole so that the advancing / retreating position can be adjusted, and abuts on the tip surface 1b of the valve stem 1a. There are provided operating parts 6c and 7c each having a tappet screw 11 which is a contact part with 1.

The first rocker arm 6 has a cylindrical roller 16 which is rotatably supported by the roller shaft 14 between the swing base 6a and the operating portion 6c and is in rolling contact with the first cam 9.
An accommodating portion 12 for accommodating the The accommodating portion 12 includes a through hole 20 penetrating in the vertical direction, and is a wall that faces in the radial direction with a first support wall 6d and a second support wall 6e that are a pair of walls that face each other in the axial direction A1. An inner side wall 6f adjacent to the swing base 6a and forming a part thereof, and an operating part 6c are formed adjacent to the outer side wall 6g. In addition, in the first embodiment, a part of the operating portion 6c is provided over the first support wall 6d.

Referring to FIGS. 3 to 5 together, the first support wall 6d is provided with bottomed cylindrical first fitting holes 6h and 6k which open toward the second support wall 6e. In the second support wall 6e,
A cylindrical second fitting hole 6k penetrating the second support wall 6e is formed coaxially with the first fitting hole 6h, and the first and second fitting holes 6h, 6k are formed.
A cylindrical roller shaft 14 having a central axis line that coincides with the rotation axis lines L2 of the rollers 16 and 17 is fitted and supported on the. Therefore, the first and second fitting holes 6h and 6k serve as support portions for the roller shaft 14. The roller 16 is rotatably supported by the roller shaft 14 via a large number of needles 18 arranged on the outer circumference thereof. In addition, the wall surface 6d of the first and second support walls 6d and 6e
1, 6e1 are opposed to the end surface of the roller 16 in the axial direction A1 via a slight gap in the axial direction A1, and are in a state capable of sliding contact with the wall surfaces 6d1, 6e1. In addition, in order to restrict the movement of the roller shaft 14 in the axial direction A1, the retaining ring 22 is mounted across the annular mounting grooves provided in the second support wall 6e and the roller shaft 14, respectively.

Both openings 12 in the vertical direction of the accommodating portion 12
Of the a and 12b, the edge 6m of the upper opening 12a that is located closer to the first cam 9 and opens upward, closer to the swing base 6a, that is, the upper surface from the inner wall 6f to the swing base 6a in the radial direction is , The first opening, the second opening on the extension surface of the wall surface 6f1 of the inner wall 6f, having a width substantially equal to the width of the upper opening 12a in the axial direction A1 (see FIG. 5).
It is located below the upper surfaces of the support walls 6d and 6e, and is adjacent to the upper opening 12a on the upper surface of the first rocker arm 6 by a part of these three walls 6d, 6e and 6f and the swing base 6a. As a result, the recess 23 is formed. Then, of the lubricating oil supplied into the valve operating chamber, the lubricating oil that has fallen or flowed into the recess 23 is
Guided by this concave portion 23, it flows into the accommodating portion 12, and the roller
16 and needle 18, roller 16 and wall surfaces 6d1 and 6e1, roller shaft 14
And is used for lubrication of each sliding portion such as the needle 18.

On the other hand, the second rocker arm 7 has a swing base portion.
An accommodating portion 13 that accommodates a cylindrical roller 16 that is rotatably supported by the roller shaft 15 and that is in rolling contact with the second cam 10 is provided between the 7a and the operating portion 7c. The accommodating portion 13 includes a through hole 21 penetrating in the up-down direction, and is a wall that is radially opposed to the first support wall 7d and the second support wall 7e, which are walls that face each other in the axial direction A1, and that swings. It is formed of an inner wall 7f adjacent to and forming a part of the base 7a, and an outer wall 7g provided adjacent to the actuating portion 7c.

Referring also to FIGS. 5 to 7, the first support wall 7d has a cylindrical first fitting hole penetrating the first support wall 7d.
7h is formed, and the second support wall 7e has a cylindrical bottomed second shape that opens coaxially with the first fitting hole 7d toward the first support wall 7d.
The fitting hole 7k is formed, and the cylindrical roller shaft 15 having a central axis line coinciding with the rotation axis line L2 of the roller 17 is fitted and supported. Therefore, the first and second fitting holes 7h and 7k are supporting portions of the roller shaft 15. And the roller 17
The roller shaft 15 has a large number of needles 19 arranged on the outer periphery thereof.
Is rotatably supported via. Further, the wall surfaces 7d1 and 7e1 of the first and second support walls 7d and 7e face the end surface of the roller 17 in the axial direction A1 with a slight gap, and are in a state capable of sliding contact with the wall surfaces 7d1 and 7e1. . In addition, in order to restrict the movement of the roller shaft 15 in the axial direction A1, the retaining ring 22 is mounted across the annular mounting grooves provided in the first support wall 7d and the roller shaft 15, respectively.

Further, like the first rocker arm 6, of the upper and lower openings 13a and 13b of the accommodating portion 13 in the vertical direction, the swing base portion 7a of the upper opening portion 13a which is located closer to the cam 10 and opens upward.
The edge 7m nearer, that is, the swing base in the radial direction from the inner wall 7f
The upper surface toward 7a has a width substantially equal to the width of the upper opening 13a in the axial direction A1, and is lower than the upper surfaces of the first and second support walls 7d and 7e on the extension surface of the wall surface 7f1 of the inner wall 7f. Is located at a portion of these three walls 7d, 7e, 7f and the swing base 7a.
As a result, a recess 24 is formed on the upper surface of the first rocker arm 7 adjacent to the upper opening 13a. Then, of the lubricating oil supplied into the valve operating chamber, the lubricating oil that has fallen or flowed into the recess 24 flows into the accommodating portion 13 guided by the recess 24, and the roller 17, the needle 19, and the roller 17 Walls 7d1, 7e1,
It is used for lubrication of each sliding portion such as the roller shaft 15 and the needle 19.

Then, as will be described later, the through holes 20 and 21 formed by the punching process have a punching direction A2 (see FIG. 14).
The cross-sectional shape in a plane orthogonal to the reference (see) is a rectangle having rounded portions at four corners, that is, portions formed in an arc shape having a predetermined radius. Therefore, by increasing the radius of this rounded portion, the walls 6d, 6 forming the receiving portions 12, 13 are formed.
The rigidity of e, 6f, 6g; 7d, 7e, 7f, 7g can be increased.

By the way, the connection switching mechanism C1 includes the first and second
A cylindrical connecting piston 25 for switching connection and disconnection of the rocker arms 6 and 7, a cylindrical restricting member 26 having a bottom portion contacting the connecting piston 25, and the restricting member 26 contacting the connecting piston 25. And a return spring 27 for urging.

The connecting piston 25 is fitted inside the roller shaft 14 so as to be slidable in the axial direction A1 and forms a hydraulic chamber 28 with the bottom portion 6h1 of the first fitting hole 6h of the first support wall 6d. To do. further,
A part of the connecting piston 25 includes the first and second rocker arms 6, 6.
When 7 is connected, it is also slidably fitted inside the roller shaft 15. On the other hand, the regulating member 26 is located inside the roller shaft 15 in the axial direction.
The bottom part that is slidably fitted to A1 and has the through hole 26a in the center part contacts the end surface of the connecting piston 25. Return spring 27
Is provided between the bottom portion of the restriction member 26 and the bottom portion 7k1 of the second fitting hole 7k of the second support wall 7e. Further, the bottom portion 7k1 is located in the central portion thereof, and vents and injects and discharges the lubricating oil, further abuts on the connecting piston 25, and the axial direction A1
To know the position of the connecting piston 25 at
A through hole 29 into which a rod-shaped jig for confirming the operation of the connecting piston 25 is inserted is formed.

The hydraulic chamber 28 is located at the center of the bottom 6h1.
Communication oil passage 30 formed in the first support wall 6d so as to open at
Through a hydraulic fluid passage 31 formed inside the rocker shaft 8 and the hydraulic pressure of the hydraulic fluid in the hydraulic fluid passage 31 is controlled by a control valve (not shown) according to the engine speed of the internal combustion engine. Reference numeral 32 is a communication hole for always communicating the hydraulic oil passage 31 and the communication oil passage 30 regardless of the rocking state of the first rocker arm 6.

The operation of the connection switching mechanism C1 will now be described. In the low speed rotation range of the internal combustion engine, since the hydraulic oil controlled to a low pressure by the control valve exists in the hydraulic chamber 28, the hydraulic chamber 28
Is in a low hydraulic pressure state, and the contact surface between the connecting piston 25 and the regulating member 26 is between the first and second rocker arms 6 and 7, as shown in FIG. Therefore, the first and second rocker arms 6 and 7 are in the disconnected state, and both rocker arms 6 and 7 are
7 can swing independently of each other, the first rocker arm 6 opens and closes the corresponding intake valve 1 at the opening and closing timing and the lift amount defined by the first cam 9, and the second rocker arm 7 corresponds. The intake valve 1 is closed or substantially closed according to the profile of the second cam 10.

Further, in the high speed rotation range of the internal combustion engine, since the hydraulic oil controlled to a high pressure by the control valve exists in the hydraulic chamber 28, the hydraulic chamber 28 is in a high hydraulic state and the connecting piston 25
Is displaced toward the second rocker arm 7 while pressing the regulating member 26 against the spring force of the return spring 27, and the roller shaft 14
And occupies a position fitted to the roller shaft 15. for that reason,
The first and second rocker arms 6 and 7 are in an interlocking state in which they are integrally connected, and both rocker arms 6 and 7 open and close both intake valves 1 at an opening / closing timing and a lift amount defined by the first cam 9. Activate.

After that, when the internal combustion engine shifts from the high speed rotation range to the low speed rotation range, the hydraulic pressure is controlled by the control valve to bring the hydraulic chamber 28 into the low hydraulic pressure state, and the connecting piston 25 is
It is pushed back into the roller shaft 14 by the spring force of the return spring 27 and occupies the position shown in FIG.

Next, a method of manufacturing the first and second rocker arms 6 and 7 will be described with reference to FIGS. The molding material of both rocker arms 6 and 7 is, for example, chrome steel, and first, by hot forging in die forging, the first material having the pilot holes for forming the through holes 20 and 21 serving as the accommodating portions is molded. Then, the outer shape of the first material, excluding the inner shape formed by the pilot hole, of the first material is subjected to sizing by die forging, which is cold forging, to form the second material. . Next, with the sizing portion of the second material tightly fitted in the mold of the press machine, in the pilot hole of the second material,
The sizing is performed by punching with the punching punch to form the through holes 20 and 21, and at the same time, the punching punch during punching presses the wall forming the pilot hole to apply pressure to the molding material. By causing the second material to undergo die forging, which is cold forging with a forming die that is completely sealed at the end of the punching process, the first and second rocker arms are
A rocker arm material that is a finished member is formed by cold forging.

The method of manufacturing the first rocker arm 6 will be described in detail below. The manufacturing process of the second rocker arm 7 up to the formation of the housing portion 13 formed of the through hole 21 is the same as that of the first rocker arm 6. Is.

Referring to FIGS. 8-10, the first material 40
Is formed by hot forging using a forming die that is divided into an upper die and a lower die (not shown). For the first material 40,
A lower hole 41 for forming the through hole 20 forming the housing portion 12 is formed, and the lower hole 41 has a substantially rectangular cross-sectional shape in a plane orthogonal to the punching direction A2. The lower hole 41 is a pair of support wall forming walls 40d and 40e formed on the first and second support walls 6d and 6e by finish cold forging including punching, and similarly the inner wall 6f and the outer side. Formed by a wall 40f for forming an inner side wall and a wall 40g for forming an outer side wall, which are respectively formed on the wall 6g,
Each of the walls 40d, 40e, 40f, 40g has a through hole 2 formed by finish cold forging, as shown by the solid line in FIGS.
0, that is, the inner side of the lower hole 41 than the wall surfaces 6d1, 6e1, 6f1, 6g1 of each wall 6d, 6e, 6f, 6g forming the housing portion 12 (indicated by a chain double-dashed line in FIGS. 9 and 10) It has a raised wall surface 40d1, 40e1, 40f1, 40g1 that is tapered so as to protrude to form a pilot hole 41. The raised wall surfaces 40d1, 40e1, 40f1 and 40g1 are arranged on both sides of the wall surface 6d1, 6e1, 6f1 and 6g1 on both sides of the parting line L3 which is substantially located on a plane that passes through the central axis L2 and is orthogonal to the hole-piercing direction A2. Tops Fd1 and F that have the surface most protruding from and parallel to the punching direction A2
e1, Ff1, Fg1 and taper parts Td1, Te forming a draft
1, Tf1, and Tg1. Also, the outer surface of the first material 40,
On both sides of the parting line L4 that is located on a plane that passes through the central axis L1 and is orthogonal to the hole-piercing direction A2,
It is a raised wall surface having a top portion F having a surface parallel to and a taper portion T forming a draft.

Then, as shown in FIG. 11, the first material 40 is set on a hydraulic press machine P and cold forged by the press machine P to further accommodate the second material 42 (see FIG. 14). A rocker arm material 43 (see FIG. 14) having the portion 12, the swing base portion 6a and the operating portion 6c is formed.

Referring also to FIG. 14, this press machine P comprises a fixed lower mold 51 and a movable upper mold 52. The lower molding die 51 includes a lower die 53 and the lower die 53.
Ring die 54 mounted on the upper surface of the
The 53 and the ring die 54 are fixed on a bed 55 of the press machine P by die holders 56, 57 and 58. Lower die
On the upper surface of 53, a molding surface 53a which is a finished shape of the lower surface of the outer shape of the first rocker arm 6 by forging is formed.
Further, in the lower die 53, a punching punch 64 described later is inserted at a position aligned with the through hole 20 which is a finished hole of the lower hole 41 in the punching direction A2, and has a shape substantially aligned with the through hole 20. And an opening edge portion 53b forming an opening having the opening edge portion 53b.
A hole punching space 5 connected to the lower side of the opening 5 and having a diameter larger than the opening edge 53b.
9 and are formed. The opening edge 53b cooperates with the punching punch 64 to form a shearing blade. On the inner surface of the ring die 54, a molding surface 54a, which is the finished shape of the peripheral side surface of the outer shape of the first rocker arm 6 by forging, is formed.

Further, a scrap discharging section 60 is provided below the lower die 53. In the scrap discharge part 60, the surplus molding material in the punching process is used for punching punch 64 and the opening edge.
Scrap 61 formed by shearing with 53b (Fig. 14 (C))
(See) to the outside of the lower mold 51,
A scrap discharge path 60a and an exhaust air supply device 60b including a blower and the like are provided. The scrap discharge path 60a is
The lower die 53 and the die holder 58 are formed so as to extend substantially horizontally and communicate with the lower end of the punching space 59. Then, one end of the scrap discharge path 60a communicates with the discharge air supply device 60b,
The other end communicates with a recovery section (not shown) for scrap 61, and the scrap 61 dropped into the scrap discharge path 60a through the hole punching space 59 is returned to the recovery section by the air flow from the discharge air supply device 60b. Is discharged.

Further, the bed 55 is provided with a knockout portion 62 for taking out the rocker arm material 43 after molding from the lower molding die 51, and a knockout pin 62b which is lifted and lowered by a knockout bar 62a is provided on the lower surface of the rocker arm material 43. Abutment, rocker arm material 43 after molding
The rocker arm material 43 is taken out from the lower molding die 51 by pushing up.

On the other hand, the upper forming die 52 having the forming punch 63 and the punching punch 64 is provided on the upper plate 66 fixed to the ram 65 which can be moved up and down in the vertical direction of the press machine P. The forming punch 63 fixed to the piston 70b forming the cylinder device 70 via the punch holders 67, 68, 69 includes:
A through hole 63 into which a punching punch 64 fixed to an upper plate 66 via the punch holders 71, 72, 73 is slidably fitted.
b is formed.

The cylinder device 70 includes a cylinder chamber 70a and a piston 70b. The cylinder chamber 70a has an upper plate 66
And a cylinder holder 74 integrally formed with the upper plate 66, and the cylinder chamber 70a is connected to a hydraulic pressure source via a hydraulic circuit to control the supply and discharge amount of the pressure oil to the cylinder chamber 70a and the hydraulic pressure. To be done. Also, punch holder
The annular piston 70b on which 73 slides oil-tightly in the center is
Cylinder chamber is slidably fitted to the piston holder 74.
It moves vertically depending on the amount of pressure oil supplied to 70a. The lower end position of the piston 70b with respect to the cylinder chamber 70a is defined by the piston holder 74 that contacts the lower surface of the piston 70b.
Is defined by the locking portion 74a.

The punch holder 68 is an upper plate.
A plurality of guide posts 75 fixed to 66 and extending vertically
The forming punch 63 is vertically slidable relative to the punching punch 64 integrally fixed to the ram 65 according to the hydraulic pressure in the cylinder chamber 70a.

Further, the molding punch 63 which is tightly fitted to the ring die 54 has a molding surface 63a which is a finished shape of the upper surface of the outer shape of the first rocker arm 6. Referring also to FIGS. 9 and 10, the hole punching punch 64 has a tip portion 64a and a base portion 64b connected to the tip portion 64a, and has a constant outer diameter in the axial direction of the hole punching punch 64. 64b is provided with an outer peripheral surface that forms the finished shape of the through hole 20 that serves as the housing portion 12 that forms the inner shape of the first rocker arm 6. Therefore, the cross-sectional shape of the base portion 64b corresponds to the cross-sectional shape of the through hole 20, and is a rectangle with four corners formed in rounded portions. Then, the tip end portion 64a of the punching punch 64 is smoothly inserted into the lower hole 41 and presses the walls 40d, 40e, 40f, 40g, so that the molding material is
A tapered outer peripheral surface 64a1 is provided so as to be pressed, compressed and allowed to flow from the punching direction A2 to the direction orthogonal to the punching direction A2. The taper angle α of this tip 64a
Is set to a draft angle β or more and the punching punch 64
At the time of descending, the punching punch 64 does not peel off the molding material during punching while maintaining the lubricating action of the lubricating film formed between the tip portion 64a and the wall surface of the pilot hole 41. As described above, the walls 40d, 40e, 40f, 40g forming the pilot hole 41 are smoothly pressed so that the molding material can be sufficiently compressed and flowed.

Next, the cold forging process of the first rocker arm 6 by the press machine P will be described. First, as shown in FIGS. 11 and 14 (A), the first material 40 is set in the lower molding die 51. Then, the ram 65 is lowered, and the sizing process by die forging is performed on the first material 40 except the prepared hole 41 by the forming punch 63. I.e. ram 65
And the forming surface 63a of the forming punch 63 comes into contact with the upper surface of the first material 40, the forging of the first material 40 is started, and the ram 65 continues to descend, as shown in FIGS. ), The bottom surface of the punch holder 67 is
When the forming punch 63 is brought into contact with the upper surface of the first puncher 63 and the lowering of the forming punch 63 is finished, the dicing process by the die forging in the first cold forging of the first rocker arm 6 is finished. During this sizing process, the forming punch 63 is acted on by a hydraulic pressure of a predetermined value in the cylinder chamber 70a, the piston 70b is in contact with the locking portion 74a, and the punching punch 64 is different from the forming punch 63. It is relatively stopped.

In this die forging, a forming punch is used.
By the pressing of 63, the first material 40 formed to be larger than the finished size in the vertical direction is compressed in the vertical direction, and the molding material is changed into the lower die 53, the ring die 54 and the molding punch 63.
Flows so as to fill the gap between the first material 40 and the first material 40, the raised wall surface on the outer surface thereof is almost eliminated, and most of the outer shape of the first rocker arm 6 excluding the shape dimension of the pilot hole 41 is its finished dimension. The outer shape of the first material 40 is formed into the shape of the outer shape of the rocker arm material 43 which is a finished member obtained by cold forging of the first rocker arm 6. On the other hand, the pilot hole 41 is formed by the flow of the molding material caused by the pressing by the molding punch 63, whereby the walls 40d, 40e,
The raised wall surfaces 40d1, 40e1, 40f1, 40g1 of 40f, 40g become a wall 42w having a further raised wall surface 42w1, and the opening area or inner diameter thereof becomes smaller than that of the first material 40.

When the first cold forging is completed, the second material is
The sized portion of 42 is tightly fitted to the lower die 53, the ring die 54 and the forming punch 63.
Further, from the state shown in FIG. 14B, the ram 65 is further lowered, so that the punching punch 64 causes the upper opening 41a of the lower hole 41, that is, the upper opening of the accommodating portion 12 on the first cam 9 side. After being inserted from 12a, the through hole 20 is formed by subjecting the lower hole 41 to sizing processing by punching. During the punching process, the pressure oil in the cylinder chamber 70a is discharged through the hydraulic pressure control circuit, and the amount of oil in the cylinder chamber 70a decreases, and the oil pressure causes the forming punch 63 to contact the ring die 54. The size is set to maintain the contact state.

As the ram 65 descends, the punching punch 64
The tapered outer peripheral surface 64a1 of the tip portion 64a flows into the prepared hole 41 of the molding material by the first cold forging by the molding punch 63, so that the raised wall surfaces 40d1, 40e1, 40f1 and 40g1 of the first material 40.
(See FIGS. 9 and 10) The wall 42w, which is further raised inward of the lower hole 41, is pressed from the punching direction A2 to a direction orthogonal to the punching direction A2 to apply pressure to the molding material. To compress and flow the molding material,
While forming the wall surfaces 6d1, 6e1, 6f1, 6g1 so that b becomes the through hole 20 having the finished size of the lower hole 41, the second material
The inside of the pilot hole 41 of 42 is moved in the punching direction A2. Further, at this time, a part of the molding material, including the one that will eventually become the scrap 61, is pressed by the punching punch 64 and flows in the pilot hole 41 in the punching direction A2.

Then, as shown in FIGS. 13 and 14C, the ram 65 approaches the bottom dead center of the stroke,
The punching punch 64 enters the punching space 59 of the lower die 63,
When the excess molding material is sheared at the opening edge portion 53b, the ram 65 reaches the bottom dead center, and the formation of the through hole 20 is completed. Then, at this point, the forming die including the lower die 53, the ring die 54, the forming punch 63, and the punching punch 64,
The completely sealed state is applied to the portion which has not been sized in the first cold forging, and the finish cold forging process including the punching and the die forging causes the first rocker arm 6 to cool. A rocker arm material 43, which is a finished member by forging, is formed. The sheared molding material falls as scrap 61 in the hole punching space 59, reaches the scrap discharge path 60a, and is discharged toward the recovery section by the discharge air from the discharge air supply device 60b.

With this punching process, the punching punch 64 presses the crystal grains of the molding material in the above-mentioned pressing direction, so that the first and second support walls of the through hole 20 (or the accommodating portion 12). 6d, 6e, inner wall 6f and outer wall 6g (see FIGS. 1 and 5)
A work-hardened layer is formed on the
As compared with the case where the pressing is not performed, the denser crystal structure is formed in the pressing direction and the rigidity is increased. The regions where the crystal structure is dense are the first and second support walls 6d and 6e,
From the wall surfaces 6d1, 6e1, 6f1, 6g1 of the inner wall 6f and the outer wall 6g, those walls 6 corresponding to each other in a direction orthogonal to the hole-piercing direction A2.
It reaches the outer surface of d, 6e, 6f, 6g, but the walls 6d, 6e, 6
The closer to f and 6g the crystal structure is, the denser the structure is and the larger the rigidity is.

The degree of work hardening and the degree to which the crystal structure becomes dense are determined by the punching punch 64 because the compression and flow of the molding material by the punching punch 64 are prevented from moving downward by the lower die 53. Since the crystal structure of the molding material to be pressed becomes dense in the punching direction A2, each wall 6d,
In 6e, 6f, and 6g, a lower end portion (a portion closer to the opening 12a on the start side of the accommodation portion 12) that is a start side portion of the punching processing is a lower end portion that is an end side of the punching processing ( Housing
It is larger at the end side of 12 toward the opening 12b), and therefore the rigidity becomes larger. Speaking of this in relation to the through holes 20, the degree of work hardening and the degree of dense crystal structure are as follows in each wall 6d, 6e, 6f, 6g.
The opening 20a on the start side of the punching process (see FIGS. 3 and 4) is closer to the opening 20b on the end side of the punching (see FIGS. 3 and 4). .

Further, in each of the walls 6d, 6e, 6f, 6g, the raised wall surfaces 40d1, 40e1, 40e1, 40f, 40g of the pilot hole 41,
The parts of 40f1 and 40g1 that are provided along the parting line L3 and correspond to the highest ridges Fd1, Fe1, Ff1, and Fg1 (see FIGS. 9 and 10) are also pressed more strongly. The degree of work hardening and the degree of denseness of the crystal structure are increased, and the rigidity is increased. And
In the first and second support walls 6d and 6e, as shown in FIG. 10, the respective fitting holes are arranged in the diametrical direction of the first and second fitting holes 6d and 6e.
Since the tops Fd1 and Fe1 extend beyond the formation range of 6h and 6k in the direction substantially orthogonal to the load acting on the roller 16 from the first cam 9 between the inner wall 6f and the outer wall 6g,
Top Fd remaining after forming the first and second fitting holes 6h and 6k
1, the portion corresponding to Fe1, the first and second fitting holes 6h, 6k
Compensating for the decrease in the rigidity of the first and second support walls 6d, 6e due to the formation of.

After the finishing cold forging is completed, the ram 65 is
Rises and returns to the top dead center of its stroke, pressure oil is also supplied to the cylinder chamber 70a, and returns to the initial state of FIG.

With reference to FIGS. 1 and 3, the rocker arm blank 43 is then ground on both end surfaces of the swing base 6a in the axial direction A1. Next, an insertion hole 6b through which the rocker shaft 8 is inserted is formed in the swing base 6a by drilling. Then, with respect to the rocker arm material 43, in order to form the communication oil passage 30 formed in the first support wall 6d, by a drill inserted from the opening 6b1 of the insertion hole 6b near the first support wall 6d, After the blind hole reaching the region where the crystal structure of the molding material becomes dense is formed from the peripheral wall surface of the insertion hole 6b, the crystal structure of the molding material of the first and second support walls 6d and 6e becomes dense. By forming the first and second fitting holes 6h and 6k by drilling in the region, the communication oil passage 30 opening to the bottom portion 6h1 of the first fitting hole 6h is formed in the region.
At this time, the first and second fitting holes 6h, 6k are
The second fitting hole, which corresponds to 40e1, 40f1, 40g1
As shown in FIG. 10 regarding 6k, it is formed so that its central axis is located approximately on the parting line L3. Next, the tapped screw 11 is screwed into the screw hole and snap ring.
A mounting groove for mounting the 22 is sequentially formed by machining, and a carburizing treatment is further applied to the entire surface including the outer surface and the inner surface.

As for the second rocker arm 7, similarly to the first rocker arm 6, the rocker arm material, which is a finished member in the finish cold forging, is ground to both end surfaces of the swing base 7a in the axial direction A1. Processing is performed, and then the insertion hole 7b through which the rocker shaft 8 is inserted is formed in each swing base portion 7a by drilling, and then the first and second fitting holes 7h and 7k are formed as described above. It is formed by drilling in a region where the crystal structure is dense. Then, the first and second fitting holes 7h, 7k
Like the fitting holes 6h and 6k of the first rocker arm 6, is a portion corresponding to the raised wall surface of the wall forming the pilot hole for forming the through hole 21, and is substantially on the parting line. It is formed such that the central axis is located. Furthermore, FIG.
As shown in FIG. 5, a through hole 29 is formed in the central portion of the bottom portion 7k1 of the second fitting hole 7k by drilling in the region. Next, a screw hole into which the tappet screw 11 is screwed, a mounting groove into which the retaining ring 22 is mounted, and the like are sequentially formed by machining, and further carburizing treatment is performed on the entire outer surface and inner surface.

Next, the operation and effect of the first embodiment configured as described above will be described focusing on the first rocker arm 6, but the same applies to the second rocker arm 7. In the finish forging process, the housing portion 12 of the roller 16 is
It is formed by sizing by punching with a punching punch 64 inserted in 41, and at the time of punching,
A wall surface where the punching punch 64 forms the pilot hole 41 of the second material 42.
The wall 42w having 42w1 is removed from the punching direction A2 to the punching direction A2.
Since the molding material is compressed and flows by pressing the molding material in a direction orthogonal to and compressing the molding material, the first and second support walls 6d and 6e, the inner wall 6f, and The outer side wall 6g has a work hardened layer and a region where the crystal structure of the molding material becomes dense in the pressing direction, so that its rigidity is increased, and at the end of the punching process, the rigidity is increased. Due to the die forging in a closed state, the second material 42 is sized even if there is a portion that has not been sized in the first cold forging step, and the first rocker arm 6 is finished by cold forging. A rocker arm material 43 including the housing portion 12 which is a member and the swing base portion 6a is formed.

As a result, the accommodating portion 12 of the roller 16 is formed by utilizing the through hole 20 formed by the punching process by the punching punch 64 in the finish cold forging step, so that the accommodating portion 12 is formed.
Can be formed with high productivity and low cost while ensuring the required dimensional accuracy.

Moreover, a work-hardened layer is formed on the first and second support walls 6d and 6e, the inner side wall 6f and the outer side wall 6g forming the accommodating portion 12 by pressing with the punching punch 64, and The rigidity is increased by forming the region where the crystal structure of the molding material is dense, so that the rigidity of the first and second support walls 6d and 6e for supporting the roller shaft 14 and the rocking base 6a are adjacent. The rigidity of the inner wall 6f is increased, and the required rigidity can be secured, and the first rocker arm 6 can be made smaller and lighter. Similarly, since the rigidity of the outer side wall 6g adjacent to the operating portion 6c is increased, the rigidity with respect to the load from the intake valve 1 acting on the operating portion 6c is increased, and the first rocker arm 6 is secured with a required rigidity. Can be made smaller and lighter.

Particularly, the first and second support walls 6d, 6e are pressed by the punching punch 64 to be molded, so that both support walls 6d, 6e are formed.
6d and 6e have a work-hardened layer and a region where the crystal structure of the molding material becomes dense in the pressing direction, so that the rigidity is increased in that region, and the roller shaft is located in that region. Since the first and second fitting holes 6h and 6k for supporting 14 are formed, the first rocker arm 6 having the first and second supporting walls 6d and 6e having the required rigidity for supporting the roller shaft 14. Can be made smaller and lighter.

Further, the raised wall surfaces 40d1, 40e1, 40f1, 40g1
Is formed at the time of forming the first material 40, so that it does not depend on the shape of the protrusion of the wall 42w including the wall for forming the support wall of the prepared hole 41 due to the flow of the forming material in the first cold forging step. The raised wall surfaces 40d1, 40e1, 40f1, 40 are surely made to correspond to the portions of the first and second support walls 6d, 6e that require large rigidity.
g1 can be formed, and the flow of the molding material into the pilot hole 41 in the first cold forging step further bulges the raised wall surfaces 40d1 and 40e1 of the support wall forming walls 40d and 40e, thereby punching a punch hole. The degree of pressing of the wall by 64 increases, the degree of work hardening and the degree of dense crystal structure increase,
Therefore, the rigidity of the first and second support walls 6d and 6e can be increased.

In each of the walls 6d, 6e, 6f and 6g forming the accommodating portion 12, the portion on the end side of the punching process has a flow of the molding material by the pressing by the punching punch 64 during the punching process. Since it is blocked by the lower die 53, the crystal structure of the molding material pressed by the punching punch 64 becomes dense in the punching direction A2 as well, so that the rigidity is large. As a result, the housing
Since the end portions of the walls 6d, 6e, 6f, 6g of 12 have a large rigidity, the rollers that make rolling contact with the first cam 9
First cam 9 acting on first rocker arm 6 via 16
The rigidity with respect to the load of being hit by is increased, and it is possible to reduce the size and weight of the first rocker arm 6 while ensuring the required rigidity.

Among the walls 6d, 6e, 6f and 6g forming the accommodating portion 12, at the end side of the punching process where the crystal structure of the molding material pressed by the punching punch 64 becomes particularly dense, the penetration is performed. Since a slight springback occurs after the hole 20 is formed, the springback causes the first and second support walls 6d,
The slight gap in the axial direction A1 between 6e and the roller 16 becomes smaller. As a result, in the portion on the end side of the first and second support walls 6d and 6e, the axial direction between the support walls 6d and 6e and the roller 16 is increased.
Since the slight gap in A1 is further narrowed and the end side portion is located under the first rocker arm 6, the oil retaining ability in the gap is improved, and the retained lubricating oil allows the roller to be retained. Each sliding part that slides by 16 rotations,
For example, roller 16 and needle 18, roller 16 and wall surfaces 6d1 and 6e
1, the lubricity of the sliding portions such as the needle 18 and the roller shaft 14 is improved, and the durability of the roller 16 and the first rocker arm 6 is improved. Moreover, since the structure for improving the holding ability is obtained by forming with the punching punch 64,
Its formation is easy.

The upper opening 12 is formed on the upper surface of the first rocker arm 6.
A concave portion 23 is formed adjacent to a, and among the lubricating oil supplied into the valve operating chamber, the lubricating oil that has dropped or flowed into the concave portion 23 is guided by the concave portion 23 and flows into the housing portion 12. ,
Since it is used for lubrication of each sliding part that slides by the rotation of the roller 16, the lubricity of each sliding part is improved.

In the first support wall 6d of the first rocker arm 6, the communication oil passage 30 is a region where the crystal structure is dense and is formed in a portion where the rigidity is increased, so that the first support wall 6d.
In addition, although the communication oil passage 30 that communicates with the hydraulic chamber 28 is formed, it is possible to suppress the decrease in the rigidity of the first support wall 6d.

In the second support wall 7e of the second rocker arm 7, the through hole 29 into which the jig is inserted is a region where the crystal structure is dense and is formed in a portion where the rigidity is increased. 2 Even though holes are formed in the support wall 7e, the second
It is possible to suppress a decrease in rigidity of the support wall 7e.

Walls 40d, 40 forming the pilot hole 41 of the first material 40
The raised wall surfaces 40d1, 40e1, 40f1 and 40g1 of e, 40f and 40g use the draft required when the first material 40 is hot forged by the forming die including the upper die and the lower die. Since it is molded, its molding becomes easy.

Next, a second embodiment of the present invention will be described with reference to FIGS. This second embodiment is the first
Only the valve operating device is different from the embodiment, and other parts have basically the same configuration. Therefore, the description of the same parts will be omitted or simplified, and different points will be mainly described. The same reference numerals are used for the same or corresponding members as those of the first embodiment.

This intake side valve operating device V2 is provided with the intake camshaft 2
And the first to third rocker arms 6, 7, 80 for opening and closing a pair of intake valves, respectively, and these rocker arms 6, 7, 80
A rocker shaft 8 for swingably supporting the rocker and a connection switching mechanism C2 for switching connection and disconnection of the first to third rocker arms 6, 7, 80.

The intake camshaft 2 has a first cam 9 for defining the swinging motion of the first rocker arm 6 and a second rocker arm 7.
The second cam 10 that defines the swinging movement of the third rocker arm 80 and the third cam 81 that defines the swinging movement of the third rocker arm 80 are formed between the two cams 9 and 10. The first cam 9 has a profile that opens and closes the intake valve with a predetermined opening timing and a predetermined lift amount, and the second cam 10 has a profile that keeps the intake valve in a resting state or slightly opens. A third cam 81 having a profile that causes the valve to remain substantially dormant.
Has a profile that opens and closes the intake valve with a larger operating angle and lift amount than the first cam 9.

Similar to the first embodiment, the first and second rocker arms 6 and 7 are provided with rocking bases 6a and 7a at one end thereof through which the rocker shaft 8 is inserted, and at the other ends thereof. , And operating portions 6c and 7c each having a tappet screw 11 serving as a contact portion with the intake valve are provided, and the first and second cams 9 and 10 are provided between the swing base portions 6a and 7a and the operating portions 6c and 7c. Are provided with accommodating portions 12 and 13 for accommodating cylindrical rollers 16 and 17 that are in rolling contact with each other.

Then, a third rocker arm which is arranged between the first and second rocker arms 6 and 7 and is arranged on the rocker shaft 8.
One end of 81 is a swing base 80a having an insertion hole 80b through which the rocker shaft 8 is inserted, and the other end is rotatably supported by the roller shaft 83 and is supported by the third cam 81. An accommodating portion 82 that accommodates a cylindrical roller 84 that makes rolling contact is provided. The accommodating portion 82 is a slit 86 formed by forming a through hole by the same punching process as in the first embodiment and then cutting the tip side of the wall forming the through hole. It is formed of a first support wall 80d and a second support wall 80e facing each other in the axial direction A1 which are also formed walls, and an inner side wall 80f forming a part adjacent to the swing base portion 80a.

The first and second support walls 80d and 80e include the support walls.
Cylindrical first and second fitting holes 80h, 80k that pass through 80d, 80e
Are formed coaxially, and the first and second fitting holes 80 are formed.
A cylindrical roller shaft 83 is fitted to h and 80k. The roller 84 is rotatably supported by the roller shaft 83 via a large number of needles 85 arranged on the outer circumference thereof. The wall surfaces 80d1 and 80e1 of the first and second support walls 80d and 80e are the rollers 84
Is opposed to the end surface of the wall surface via a slight gap in the axial direction A1, and is in a state capable of sliding contact with the wall surfaces 80d1 and 80e1. In addition,
In order to restrict the movement of the roller shaft 83 in the axial direction A1, the retaining ring 22 is mounted across the annular mounting grooves provided on the second support wall 80e and the roller shaft 83, respectively. Furthermore the first
A recess 87 similar to the recesses 23, 24 of the embodiment is formed.

Further, the cylinder head 88 below the third rocker arm 80 is provided with a lost motion mechanism 89 for exerting an urging force for rollingly contacting the roller 84 with the third cam 81 to the third rocker arm 80. This lost motion mechanism 89 has a bottomed holding hole formed in the cylinder head 88.
Lifter 90 with a bottom fitted slidably into 88a and holding hole 8
A compression coil spring 91 as an elastic member arranged between the bottom of 8a and the lifter 90 is provided. Then, the third rocker arm 80 has a receiving portion 80n that abuts the lifter 90 to receive the spring force of the compression coil spring 91 as an urging force. It is formed by cold forging that projects from the lower surface of the first support wall 80d, which is also the edge of the side opening, and forms the rocker arm material.

The connection switching mechanism C2 includes a cylindrical connecting piston 25 for switching connection and disconnection of the first and third rocker arms 6 and 80, and the second and third rocker arms 7 and 80.
Cylindrical connecting pin 92 for switching connection and disconnection of
A cylindrical restricting member 26 having a bottom portion that abuts the connecting pin 92, and a return spring that urges the connecting pin 92 to abut the connecting piston 25 and the restricting member 26 to abut the connecting pin 92. 27 and.

The connecting piston 25 is fitted inside the roller shaft 14 so as to be slidable in the axial direction A1 and forms a hydraulic chamber 28 with the bottom of the first fitting hole 6h of the first rocker arm 7. Further, a part of the connecting piston 25 is also slidably fitted inside the roller shaft 83 when the first and third rocker arms 6 and 80 are connected. The connecting pin 92 is fitted inside the roller shaft 83 so as to be slidable in the axial direction A1, and a part thereof is connected to the roller shaft 15 when the second and third rocker arms 7 and 80 are connected.
It is also slidably fitted inside. On the other hand, the regulation member 26
The bottom portion, which is slidably fitted in the roller shaft 15 in the axial direction A1 and has the through hole 26a at the center, abuts on the end surface of the connecting pin 92. The return spring 27 is provided between the bottom of the regulation member 26 and the bottom of the second fitting hole 7k. Also, on the bottom 7k1,
A through hole 29 is formed at the central portion.

The operation of the connection switching mechanism C2 will now be described. In the low speed rotation range of the internal combustion engine, as in the first embodiment,
Since the hydraulic oil controlled to a low pressure by the control valve exists in the hydraulic chamber 28, the hydraulic chamber 28 is in a low hydraulic pressure state, and as shown in FIG. 15, the contact surface between the connecting piston 25 and the connecting pin 92 is the first. Between the first and third rocker arms 6 and 80, the contact surface between the connecting pin 92 and the regulating member 26 is the second and third rocker arms 7 and 80.
Between Therefore, the first to third rocker arms 6,
7, 80 are respectively in the released state, the first rocker arm 6 opens and closes the corresponding intake valve at the opening and closing timing and the lift amount defined by the first cam 9, and the second rocker arm 7 corresponds. The intake valve is closed or substantially closed depending on the profile of the second cam 10.
The third rocker arm 80 is a lost motion mechanism.
The spring force of 89 causes the roller 84 to swing in a state of rolling contact with the third cam 81 regardless of the opening / closing operation of both intake valves.

Further, in the high speed rotation range of the internal combustion engine, since the hydraulic oil controlled to a high pressure by the control valve exists in the hydraulic chamber 28, the hydraulic chamber 28 is in a high hydraulic state and the connecting piston 25
Is displaced toward the third rocker arm 80 while pressing the connecting pin 92 against the spring force of the return spring 27, and both roller shafts
The connecting pin 92 occupies the position where it is fitted to 14, and 83
While displacing the regulating member 26 against the spring force of 27, the regulating member 26 is displaced toward the second rocker arm 7 and occupies a position where both roller shafts 83, 7 are fitted. Therefore, the first to third rocker arms 6, 7 and 80 are in an interlocking state in which they are integrally connected, and the first and second rocker arms 6 and 7 respectively have both intake valves,
The opening / closing operation is performed at the opening / closing timing and the lift amount defined by the third cam 81 slidingly contacting the roller 84 of the third rocker arm 80.

After that, when the internal combustion engine shifts from the high speed rotation range to the low speed rotation range, the hydraulic pressure control of the control valve causes the hydraulic pressure chamber 28 to be in the low hydraulic pressure state, and the connecting piston 25 and the connecting pin 92 are returned. Due to the spring force of spring 27, roller shaft 14
15 is pushed back into the roller shaft 83 and the inside of the roller shaft 83, respectively.
Occupies the position shown in.

In the second embodiment, the first and second rocker arms 6 and 7 are molded by the same manufacturing method as in the first embodiment. Also, the third rocker arm 80
Processing process of the slit 86 that configures the housing portion 82, the communication oil passage 30
And the first and second rocker arms 6 and 7 except for the processing step of the through hole 29. Then, as described above, the slit 86 has the first and second support walls 80d and 80e forming the through hole formed by the punching process of the first embodiment.
It is formed by cutting the wall corresponding to the tip end portion and the outer wall of the.

Therefore, according to the second embodiment, it is the same as the first embodiment except that the communication oil passage 30 and the through hole 29, which are the structures peculiar to the first and second rocker arms 6 and 7, are concerned. In addition to the actions and effects of, the following actions and effects are exhibited. That is, in the first support wall 80d of the accommodating portion 82, the receiving portion 80n on which the spring force of the lost motion mechanism 89 acts is provided at the edge portion of the opening of the through hole on the end side of the punching process that increases the rigidity. Since the receiving portion 80n having the required rigidity can be formed without increasing the size, the third rocker arm 80 can be reduced in size and weight.

Hereinafter, an example in which a part of the configuration of the above-described example is modified will be described with respect to the modified configuration.
In the above-described embodiment, the sizing process in the first cold forging step may cause a part of the outer shape of the rocker arm material 43 to be the finished shape in the cold forging, but in the first cold forging step, The entire outer shape of the rocker arm material 43 may be formed into a finished shape by sizing. Further, in the second embodiment, the receiving portion 80n may be the peripheral edge portion of the opening on the end side of the punching process in the through hole formed by the punching process, and therefore the second supporting portion 80n.
It may be formed on the lower surface of the e or inner wall 80f. further,
The recesses 23, 24, 87 may not be provided.

In the above embodiment, the raised wall surface was formed of the first material, but the wall surface of the pilot hole was formed by the first cold forging.
Since the molding material also rises when it flows into the pilot hole, in order to form a region where the work-hardened layer and the crystal structure of the molding material become dense, the raised wall surface must be punched As long as it is molded on the second material before processing,
The first material does not necessarily have to have the raised wall surface.

Further, in the above embodiment, the lower molding die 51 molded the lower surface and the peripheral side surface of the outer shape of the first rocker arm 6, and the upper molding die 52 molded the upper surface of the outer shape of the first rocker arm 6. The lower mold of the first rocker arm 6 may form the upper surface and the peripheral side surface of the outer shape of the first rocker arm 6, and the movable upper mold may mold the lower surface of the outer shape of the first rocker arm 6. The punching punch 64 is inserted into the pilot hole 41 from the opening (the portion corresponding to the opening 12b in FIG. 3) of the surface corresponding to the lower surface of the first rocker arm 6 with respect to the second material 42, and the knockout pin 62b.
Is the first rocker arm 6 against the rocker arm material 43.
Will come into contact with the upper surface (surface on the cam side) of. By doing so also, except for the action and effect based on the difference in the insertion direction of the punch punch 64 with respect to the second material 42,
The same operation and effect as those of the embodiment are exhibited.

[Brief description of drawings]

FIG. 1 is a side view, partly in section, of a valve train for an internal combustion engine in which a rocker arm according to a first embodiment of the present invention is used.

FIG. 2 is a sectional view taken along line II-II of FIG.

[FIG. 3] III-III of FIG. 2 when a roller or the like is removed
It is a line sectional view.

4 is a sectional view taken along line IV-IV of FIG. 2 when a roller and the like are removed.

FIG. 5 is a plan view of the first rocker arm with the rollers and the like removed.

6 is a sectional view taken along line VI-VI of FIG. 2 when a roller and the like are removed.

7 is a VII-VII of FIG. 2 when a roller and the like are removed.
It is a line sectional view.

FIG. 8 is a plan view of the first material of the first rocker arm.

9 is a sectional view taken along line IX-IX in FIG.

10 is a cross-sectional view taken along line XX of FIG.

FIG. 11 is a cross-sectional view of the press machine in which the first material is set.

FIG. 12 is a sectional view of the press machine in a state where the first cold forging is applied to the first material.

FIG. 13 is a cross-sectional view of the press machine in a state where the second material is subjected to finish cold forging.

FIG. 14 is a cross-sectional view of essential parts of the press machine when the states of FIGS. 11 to 13 are cut along planes different from each other by 90 °.

FIG. 15 is a sectional view showing a second embodiment of the present invention and corresponding to FIG. 2 of the first embodiment.

16 is a sectional view taken along line XVI-XVI of FIG.

[Explanation of symbols]

1 ... Intake valve, 2 ... Intake cam shaft, 3 ... Valve guide, 4 ... Retainer, 5 ... Valve spring, 6,7 ... Rocker arm, 6a, 7a ... Swing base, 6c, 7c ... Actuating part, 6d, 6e, 7d, 7e ... Support wall, 8
… Rocker shaft, 9, 10… Cam, 11… Tappet screw, 12, 13
… Accommodating parts, 14, 15… Roller shafts, 16,17… Rollers, 18,19
... Needle, 20, 21 ... Through hole, 22 ... Retaining ring, 23, 24 ... Recess, 25 ... Connecting piston, 26 ... Restricting member, 27 ... Return spring,
28 ... Hydraulic chamber, 29 ... Through hole, 30 ... Communication oil passage, 31 ... Hydraulic oil passage, 32 ... Communication hole, 40 ... First material, 40d, 40e, 40f, 40g ...
Wall, 40d1, 40e1, 40f1, 40g1 ... Raised wall surface, 41 ... Prepared hole, 42
… Second material, 42w… Wall, 43… Rocker arm material, 51… Lower mold, 52… Upper mold, 53… Lower die, 54… Ring die, 55… Bed, 56 ～ 58… Die holder, 59… Drilling hole Space, 60 ... Scrap discharge part, 61 ... Scrap, 62 ...
Knockout part, 63 ... forming punch, 64 ... punching punch,
65 ... Ram, 66 ... Upper plate, 67, 68, 69 ... Punch holder, 70 ... Cylinder device, 71, 72, 73 ... Punch holder,
74 ... Piston holder, 75 ... Guide post, 80 ... Rocker arm, 80n ... Receiving part, 81 ... Cam, 82 ... Receiving part, 83 ... Roller shaft, 84 ... Roller, 85 ... Needle, 86 ... Slit, 87 ...
Recessed portion, 88 ... Cylinder head, 89 ... Lost motion mechanism, 90 ... Lifter, 91 ... Compression coil spring, 92 ... Connection pin,
V1, V2 ... Intake side valve operating device, C1, C2 ... Connection switching mechanism, A1 ...
Axial direction, A2 ... Hole punching direction, L1 ... Central axis line, L2 ... Rotation axis line, L3, L4 ... Parting line, P ... Press machine.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01L 1/18 F01L 1/18 N 13/00 301 13/00 301V (72) Inventor Tetsuo Kubota Fuchu-gun, Kyoto 22, Chitose, Mineyama-cho Nisshin Seisakusho Co., Ltd. (72) Inventor Takeya Harada 1-4-1, Chuo, Wako-shi, Saitama Honda R & D Co., Ltd. (72) Inventor Hisaki Kobayashi, Wako-shi, Saitama 1-4-1 Incorporated Honda Technical Research Institute (72) Inventor Noriyuki Yamada 1-4-1 Chuo, Wako-shi, Saitama Honda Technical Research Institute F-term (reference) 3G016 AA06 AA19 BA18 BB09 BB10 BB12 BB17 BB22 CA02 CA04 CA12 CA21 CA44 CA52 DA08 DA22 EA02 FA04 GA01 3G018 AA05 AA06 AB03 AB04 AB16 BA11 BA12 BA13 BA17 CA19 CB02 CB06 DA08 DA11 DA14 DA28 DA81 FA02 FA03 FA07 GA 14 GA17 GA18 4E087 AA10 CA11 CA13 CB03 DA04 EC12 HA61

Claims (5)

[Claims] 1. An accommodating portion formed by a wall including a pair of supporting walls for accommodating a roller in rolling contact with a rotating cam and supporting a roller shaft for rotatably supporting the roller, and the accommodating portion. A first radial wall that is a wall of the rocking base, which is adjacent in the radial direction, and is rockably supported by a rocker shaft inserted through the rocking base, and the cam opens and closes the engine valve. In a rocker arm manufacturing method for manufacturing a rocker arm of a valve operating device for an internal combustion engine, in which a rocking motion is defined by a working process including a cold forging process for molding the rocking base, the cold forging process includes: A first forging step of forming a second material by subjecting a first material having a hole to a sizing process by die forging except for the prepared hole; and a state in which a sizing part of the second material is closely fitted to a forming die. Then, in the pilot hole, A wall that forms a through hole for forming the accommodating portion by performing a sizing process by punching with a punch that is a component of the shape mold, and at the same time, the punch that is performing the punching process forms a pilot hole. By pressing on the molding material of the second raw material, the second raw material is subjected to die forging with the molding die that is in a completely sealed state at the end of the punching process, and the rocker arm. A finisher forging step of forming a rocker arm material, which is a finished member by cold forging, and a method of manufacturing a rocker arm, comprising: 2. The rocker arm has a receiving portion with which a lost motion mechanism for biasing the rocker arm toward a cam abuts on a peripheral portion of an opening of the accommodating portion, and the receiving portion is provided in the through hole. The method for manufacturing a rocker arm according to claim 1, wherein the cold forging step is formed on a peripheral portion of the opening on the end side of the punching process. 3. The accommodating portion is constituted by the through hole itself, and the rocker arm has an operating portion provided with an abutting portion that abuts against the engine valve, and the operating portion sandwiches the through hole. The rocker arm manufacturing method according to claim 1, wherein the rocker arm is formed by being radially adjacent to a second radial wall facing the first radial wall and being formed in the cold forging step. 4. The method of manufacturing a rocker arm according to claim 3, wherein the punch is inserted from an opening of the pilot hole on the cam side. 5. The wall surface of the pair of support walls forms a small gap in the axial direction with which the roller can slide, and the side of the through hole where the punching process ends. The rocker arm manufacturing method according to any one of claims 1 to 4, wherein the opening of the rocker arm is located below the rocker arm.