JPH0130567Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a valve train for a SOHC four-valve internal combustion engine.

Conventionally, in order to improve intake and exhaust efficiency and improve output performance, two intake and exhaust valve ports are opened in the combustion chamber, and these valve ports are opened and closed by the two intake and exhaust valves, respectively. I did it like this
SOHC type four-valve internal combustion engines are known.

By the way, in such engines, it is desirable to place the spark plug in the center of the combustion chamber in order to increase the combustion efficiency of the air-fuel mixture in the combustion chamber, but in conventional SOHC engines, it is preferable to place the spark plug in the center of the combustion chamber. Since the valve drive camshaft and the intake and exhaust side rocker arm shafts are disposed in the combustion chamber, it has been difficult to dispose the spark plug in the center of the combustion chamber because these obstacles get in the way.

The present invention was developed in view of the above circumstances, and its purpose is to provide a valve train for a SOHC four-valve internal combustion engine, in which the spark plug can be placed in the center of the combustion chamber. .

According to the present invention, in order to achieve the above objective, SOHC
The four-valve type internal combustion engine is characterized in that a through hole for insertion of a spark plug, which is attached to the upper wall of the central part of the combustion chamber, is formed on either the intake side or exhaust side rocker arm shaft.

An embodiment of the present invention will be described below with reference to the drawings.

The engine body E of the SOHC type four-valve internal combustion engine includes a cylinder block 1 and a cylinder head 2 which is polymerically bonded to the cylinder block 1 via a gasket 3. The piston 5 is slidably fitted. Further, a combustion chamber 6 facing the upper surface of the piston 5 is formed on the inner surface of the cylinder head 2, and a roof surface 7 of this combustion chamber 6 is formed.
are roof-shaped with opposing slopes. Two intake valve ports 8a, 8b with the same diameter are opened in parallel on one side of the roof surface 7 of each combustion chamber 6, and two intake valve ports 8a, 8b with a slightly smaller diameter than the intake valve ports 8a, 8b are opened on the other side. Exhaust valve ports 12a and 12b are bored in parallel. Thus, the two intake valve ports 8a, 8b are connected to the two exhaust valve ports 12a, 1, respectively.
It faces 2b.

Intake ports 9a and 9b formed in the cylinder head 2 are communicated with the two intake valve ports 8a and 8b, and these intake ports 9a and 9b are gathered into one in the cylinder head 2 and connected to the cylinder head. 2, and communicates with a fuel supply device, such as a carburetor, through an intake manifold. The two exhaust valve ports 12a and 12b are exhaust ports 13a and 13b formed in the cylinder head 2.
These exhaust ports 13a, 13b
are gathered into one line within the cylinder head 2, opened on the other side of the cylinder head 2, and communicated with the exhaust system via an exhaust manifold.

The cylinder head 2 has the intake valve ports 8a, 8.
A pair of intake valves 11a, 11b that open and close b, and a pair of exhaust valves 14a, 14b that open and close the exhaust valve ports 12a, 12b are supported slidably up and down, respectively, and the intake valves 11a, 11b and the exhaust valve 14a and 14b refer to the central axis L- of the cylinder 4.
They are arranged so that their upper ends on both sides of L are inclined away from each other. The intake valve 11a, 1
A valve operating camshaft 17 is rotatably supported on the cylinder head 2 directly above the combustion chamber 6 between the exhaust valve 1b and the exhaust valves 14a and 14b. The valve drive camshaft 17 is rotationally driven in conjunction with the crankshaft as usual. In addition, two intake valves 11a, 11
b and the valve drive camshaft 17, and the two exhaust valves 14.
a, 14b and the valve drive camshaft 17, the cylinder head 2 has an intake side rocker arm shaft 1, respectively.
9 and the exhaust side rocker arm shaft 20 are connected to the camshaft 17.
are fixedly supported in parallel with each other. Two intake-side rocker arms 23a, 23b per cylinder are swingably supported on the intake-side rocker arm shaft 19, and these rocker arms 23a, 23b
The outer ends of the two abut against the upper ends of the intake valves 11a and 11b via the adjuster 25, and the respective slipper surfaces 27 at the inner ends abut on the intake side valve drive cams 29 of the valve drive camshaft 17, respectively. being touched.
In addition, the exhaust side Rotsuka arm shaft 20 has two cylinders per cylinder.
Two exhaust side rocker arms 24a and 24b are pivotably supported, and these rocker arms 24a and 24b are pivotably supported.
The outer ends of a and 24b are brought into contact with the upper ends of the exhaust valves 14a and 14b via the adjuster 26, and each slipper surface 28 at the inner end is brought into contact with the exhaust side valve cam 30 of the valve camshaft 17. being touched. Then, when the valve drive camshaft 17 is rotated, the intake side and exhaust side rocker arms 23a, 23b and 24a, 24
b swings around rocker arm shafts 19 and 20, respectively, and has intake and exhaust valves 11a, 11b, 14a, 14.
b can be opened and closed in cooperation with valve springs 15 and 16.

A seal packing 21 is placed on the cylinder head 2.
A head cover 22 is attached through the cap.

Thus, the intake side rocker arm shaft 19 and the two intake side rocker arms 23a, 2 supported thereon.
3b has a special structure. This structure will be explained mainly with reference to FIG. 3. A flat expanded portion 31 is formed on the intake side rocker arm shaft 19 between the two intake side rocker arms 23a and 23b. , a circular through hole 32 is formed. In addition, two intake side rocker arms 23
The bearing portions 33a and 33b of the bearing portions 33a and 23b are formed in a U-shape with an open top surface.
a and 33b are attached to and supported by the rocker arm shaft 19 from below so as to be able to swing freely. Note that since the force from the valve operating cam 29 and the intake valves 11a, 11b is applied only from bottom to top on the rocker arms 23a, 23b, the bearing portion 33 is
There is no problem even if a and 33b are U-shaped.

Above the combustion chamber 6, a hollow cylindrical plug guide tube 34 is erected in the cylinder header 2, and the central axis l-l of the plug guide tube 34 is aligned with the combustion chamber 6.
It is oriented approximately at the center of Further, the plug guide tube 34 is connected to the through hole 32 of the intake side rocker arm shaft 19.
The upper end of the opening is opened to the outside. A fitting hole 35 formed in the head cover 22 is fitted into the upper end of the plug guide tube 34, and a packing 36 is interposed between the outer periphery of the plug guide tube 34 and the inner surface of the head cover 22.

The spark plug P is inserted into the guide tube 34 from the upper end of the opening of the plug guide tube 34, and the plug P
is a screw hole 37 opened in the center of the upper wall of the combustion chamber 6.
is screwed onto.

When the valve train camshaft 17 is rotated by engine operation, each of the two intake and exhaust side rocker arms 23
a, 23b and 24a, 24b swing around the intake and exhaust side rocker arm shafts 19 and 20, respectively, and cooperate with valve springs 15, 16 to close the two intake valves 11a, 11b and the exhaust valves 14a, 14b.
can be opened and closed at predetermined timing.

In the above embodiment, the intake side rocker arm shaft 19
In the above description, the enlarged portion 31 having the through hole 32 is formed, and the bearing portions 33a, 33b of the two intake side rocker arms 23a, 23b are formed in a U-shape.
0 and rocker arms 24a, 24b may be formed into such a special structure.

As described above, according to the present invention, in a SOHC four-valve internal combustion engine, there is a through hole for insertion of a spark plug attached to the upper wall of the central part of the combustion chamber on either the intake side or the exhaust side rocker arm shaft. Since we have formed
The spark plug can be disposed approximately in the center of the combustion chamber without being obstructed by the valve drive camshaft or rocker arm shaft, and the combustion efficiency in the engine can be greatly improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the device according to the present invention; FIG. 1 is a longitudinal sectional view thereof, FIG. 2 is a view taken along the line shown in FIG. 1, and FIG. 3 is a perspective view of the main parts of the device according to the present invention. be. P...Spark plug, 6...Combustion chamber, 8a, 8b
...Intake valve port, 11a, 11b...Intake valve, 12
a, 12b... Exhaust valve port, 14a, 14b... Exhaust valve, 19, 20... Intake, exhaust side rocker arm shaft, 23a, 23b... Intake side rocker arm, 2
4a, 24b... Exhaust side rocker arm, 29, 3
0...Intake, exhaust side valve operating cam, 32...Through hole.

Claims (1)

[Scope of utility model registration request] Two combustion chambers each having an intake valve port and an exhaust valve port open, two intake valves and an exhaust valve each opening and closing the intake valve port and exhaust valve port, respectively, and an intake side rocker arm above the combustion chamber. two intake side rocker arms that are swingably supported on a shaft and connect the valve drive cam and the two intake valves; and two intake side rocker arms that are swingably supported on a shaft of the exhaust side rocker arm on the combustion chamber and connect the valve drive cam and the valve drive cam. In a valve operating system for a SOHC four-valve internal combustion engine, comprising two exhaust-side rocker arms that connect the two exhaust valves, on either one of the intake-side and exhaust-side rocker arm shafts,
A SOHC characterized by having a through hole for inserting a spark plug attached to the upper wall of the central part of the combustion chamber.
A valve train for a type 4-valve internal combustion engine.