JP2500114B2 - Valve mechanism of SOHC type internal combustion engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a SOHC type valve operating mechanism for an internal combustion engine in which a spark plug is provided at the center of the upper part of a combustion chamber and a rocker arm on the intake side and a rocker arm on the exhaust side are commonly supported by one rocker arm shaft.

[0002]

2. Description of the Related Art In a SOHC type valve operating mechanism, it has been conventionally performed to support a rocker arm on the intake side and a rocker arm on the exhaust side with a common rocker arm shaft.
In No. 12 and Japanese Utility Model Application No. 60-37252, a camshaft is arranged above the rocker arm shaft, and
SOHC equipped with 4 valves for each cylinder with a spark plug arranged in the upper center of the combustion chamber for improving combustion efficiency
A mold valve mechanism is disclosed.

[0003]

However, when the camshaft is arranged above the rocker arm shaft, the rocker arm can be downsized and the number of rotations can be increased, but the head height can be increased and the camshaft can be increased. There is a problem in that a cam holder for supporting the rocker arm and a rocker holder for supporting the rocker arm shaft are separately required, resulting in a large number of assembling steps.

For the center plug system which is most advantageous for knocking, it is necessary to dispose the rocker arm shaft above so as not to interfere with the spark plug.
Moreover, unless the rocker arm shaft is located approximately in the center between the intake valve and the exhaust valve, one of the rocker arms becomes large and the number of rotations cannot be increased.

Since the camshaft which requires a large support rigidity is at a high position, the cam holder which stands upright above the cylinder head and supports the camshaft requires a large member cross-sectional dimension, which makes the structure of the cylinder head larger. It was inevitable.

An object of the present invention is to reduce the number of parts and the number of assembling steps and to secure the supporting rigidity of the cam shaft and the rocker arm shaft while improving the combustion efficiency by the center plug system, thereby making the valve operating chamber compact. It is to provide a valve mechanism for an internal combustion engine that contributes.

[0007]

In order to solve the above problems, one camshaft and one rocker arm shaft are arranged above the cylinder head on the cylinder bore, and intake valves are provided on both sides of the rocker arm shaft. An internal combustion engine in which an exhaust valve is disposed, an intake side rocker arm and an exhaust side rocker arm are commonly supported by the one rocker arm shaft, and a spark plug is disposed in the upper center of the combustion chamber of the cylinder head, Above the cylinder head, the rocker arm shaft is arranged substantially in the center between the intake valve and the exhaust valve, and the cam shaft is arranged close to either side of the valve. The upper deck has a shaft holder that supports the rocker arm shaft and the cam shaft. A plug insertion cylinder that is inclined to the side opposite to the cam shaft on the side of the shaft holder and reaches the spark plug portion is formed upright integrally with the cylinder head, and between the shaft holder and the plug insertion cylinder. A connecting wall for connecting and fixing them above the upper deck is integrally formed with the cylinder head.

[0008]

[Operation] The center plug system has excellent combustion efficiency, and the rocker arm shaft is located approximately in the center of the intake valve and the exhaust valve to bring the camshaft closer to either the intake side or the exhaust side, while the spark plug is Since it is tilted to the opposite side, interference between the plug insertion cylinder and the camshaft can be avoided, the head height can be reduced, and the plug insertion cylinder is arranged on the side of the shaft holder, Compactness can be achieved.

By forming the cam holder and the rocker holder, which are shaft holders, integrally with the cylinder head, the number of parts and the number of assembly steps can be reduced, and the plug insertion cylinder is also integrally formed with the cylinder head.
There is no need to provide a separate plug insertion pipe, and a connecting wall that connects and fixes the shaft holder and the plug inserting cylinder to each other above the upper deck is formed integrally with the cylinder head, so the number of parts does not increase and the cam does not increase. The support rigidity of the shaft and the rocker arm shaft can be significantly improved.

[0010]

Embodiments Embodiments will be described below with reference to the accompanying drawings.

1 to 3 show an embodiment according to the present invention, in which 1 is a cylinder head, 11 and 15 are valves, 21 is a spark plug, 31 is a rocker arm shaft, 41 and 45 are rocker arms, 51 is a camshaft,
71 is a head cover.

A cylinder head 1 is mounted and fixed by bolts 9 on a cylinder block having a plurality of cylinder bores (not shown), and a pair of intake ports 3 are arranged from the right side in a combustion chamber 2 facing each cylinder bore. A pair of exhaust ports 4 are opened from the left side. An intake valve 11 and an exhaust valve 15 are provided at the openings of the ports 3 and 4, and 14 and 18 are valve springs.

Further, an electrode 22 of a spark plug 21 is provided in the upper center of the combustion chamber 2 surrounded by a total of four ports 3 and 4.
Is provided, and this spark plug 21 is provided with the intake valve 11
A water jacket 5 is provided that is inclined to the side and around the exhaust port 4.

V-shaped intake valve 11 and exhaust valve 1
One rocker arm shaft 3 is located above the center of 5
1, the rocker arm shaft 31 is arranged with the axis C1 slightly offset from the cylinder bore axis C0 toward the exhaust valve 15 side.

Exhaust side rocker arms 45, 45 are provided in common on both sides of the rocker arm shaft 31 above the cylinder bore axis C0, and intake side rocker arms 41, 41 are commonly supported on the outside of the rocker arm shafts 45, 45, respectively. The drive parts 42 and 46 at the tip end of the valve contact the stems 12 and 16 of the valves 11 and 15 via the adjusting screws 43 and 47.

A camshaft 51 is arranged below the rocker arm shaft 31, and the camshaft 51 is arranged with its axis C2 offset relatively large from the rocker arm shaft axis C1 toward the exhaust valve 15 side. On the exhaust side cams 53, 53 on both sides of the journal 52 of the cam shaft 51 and the intake side cams 54, 54 on the outside thereof, the slipper parts 44, 48 at the base ends of the rocker arms 41, 45 are provided.
Are in contact with each other.

In the above, the cam holder 50, the rocker holder 30, and the plug insertion cylinder 20 are arranged in a line above the upper deck 5a of the cylinder bore axis C0 of the cylinder head 1 on the same plane orthogonal to the axis of the cam shaft 51. And molded integrally with the cylinder head 1,
Further, the journal 52 of the cam shaft 51 is connected to the cams 53, 5
The diameter is larger than 4.

By thus forming the journal 52 of the camshaft 51 to have a larger diameter than the cams 53 and 54, the camshaft 51 is integrally formed on the cylinder head 1 together with the rocker holder 30 and the plug insertion cylinder 20. It can be easily inserted and supported.

A cam holder 50 having a circular receiver in which a journal 52 of a cam shaft 51 is rotatably fitted.
A rocker holder 30 having a circular rocker arm shaft support portion and a plug insertion cylinder 20 having a plug insertion hole 29 are formed upright integrally with the upper deck 5a of the cylinder head 1, and the plug insertion cylinder 20 and the rocker holder 30 are formed. And a second connecting wall 50a connecting and fixing the rocker holder 30 and the cam holder 50 to each other above the upper deck 5a, and a second connecting wall 50d connecting and fixing the rocker holder 30 and the cam holder 50 to each other above the upper deck 5a.
And integrally molded with.

Further, the plug insertion cylinder 20 and the first connecting wall 50
Since the cam holder 50 is arranged in a line, the a, the rocker holder 30, the second connecting wall 50d, and the cam holder 50 are arranged in a row, so that high rigidity can be obtained while being compact.

The rocker arm shaft 31 is inserted into the rocker holder 30 of the shaft holder so as to be rotatably supported, or as shown by an imaginary line, a screw hole 50b is formed on the upper side of the rocker shaft support portion of the shaft holder to provide a screw. Stop rotation by 50c. The shaft holder and the upper end of the plug insertion cylinder 20 are connected by a connecting wall 50a, and sufficient rigidity can be ensured even if the screw hole 50b is provided in the upper portion of the shaft holder.

Two intake side rocker arms 41, 41
Is bent so as to come close to the upper part of the plug insertion tube 20,
A web washer 39 is provided on the rocker arm shaft 31 outside the intake-side rocker arm 41 so as to be interposed between adjacent rocker arms on the cylinder side.

A head cover 71 for covering the above valve operating mechanism is mounted and fixed on the cylinder head 1, and the head cover 71 is provided.
The plug insertion hole portion 72 provided in is connected to the plug insertion cylinder 20.

[0024]

As described above, according to the present invention, the SO in which the rocker arms on the intake side and the exhaust side are commonly supported by one rocker arm shaft by the center plug method.
In the HC type valve operating mechanism, it is possible to reduce the number of parts and the number of assembling steps while improving the combustion efficiency. In particular, the supporting rigidity of the cam shaft and the rocker arm shaft is improved and the valve operating chamber is made compact. be able to.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a valve mechanism showing an embodiment.

FIG. 2 is a plan view of the main part.

FIG. 3 is a perspective view of the main part.

[Explanation of symbols]

1 ... Cylinder head, 2 ... Combustion chamber, 5a ... Upper deck, 11 ... Intake valve, 15 ... Exhaust valve, 20 ... Plug insertion cylinder, 21 ... Spark plug, 30 ... Rocker holder (shaft holder), 31 ... Rocker arm shaft, 4
DESCRIPTION OF SYMBOLS 1 ... Rocker arm, 45 ... Rocker arm, 50 ... Cam holder (shaft holder), 50a ... 1st connection wall (connection wall), 50b ... Screw hole, 50c ... Screw, 50d ... 2nd connection wall, 51 ... Cam shaft, 71 ... Head cover, C0
… Cylinder bore axis.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area F02F 1/24 F02F 1/24 R

Claims (2)

(57) [Claims] 1. A camshaft and a rocker arm shaft are arranged above a cylinder head on a cylinder bore, intake valves and exhaust valves are arranged on both sides of the rocker arm shaft, and an intake side rocker arm is provided. An internal combustion engine in which an exhaust side rocker arm is commonly supported by the one rocker arm shaft, and a spark plug is arranged in the upper center of the combustion chamber of the cylinder head,
Above the cylinder head, the rocker arm shaft is arranged substantially in the center between the intake valve and the exhaust valve, and the cam shaft is arranged close to either side of the valve. On the upper deck of the cylinder head, there is provided a shaft holder for supporting the rocker arm shaft and the cam shaft, and a plug insertion cylinder that is inclined to the side opposite to the cam shaft on the side of the shaft holder and reaches the spark plug portion. A moving wall of the SOHC type internal combustion engine, characterized in that it is integrally formed upright and a connecting wall for connecting and fixing the shaft holder and the plug insertion cylinder to each other is formed integrally with the cylinder head between the shaft holder and the plug insertion cylinder. Valve mechanism. 2. The rocker arm shaft support portion formed on the shaft holder above the support portion above,
A screw hole for attaching the rotation preventing member of the rocker arm shaft is formed, and an upper end portion of the shaft holder having the screw hole and an upper end portion of the plug insertion cylinder are connected by the connecting wall. Valve mechanism for SOHC type internal combustion engine.