JPH076368B2 - SOHC type multi-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention has a spark plug arranged facing the ceiling surface of a combustion chamber and rotatably arranged above the combustion chamber. The intake side and exhaust side rocker arm shafts are supported by holder members on both sides of one cam shaft, and the intake side rocker arm shaft has 1
An intake side rocker arm that interlocks and connects one intake valve and cam shaft per cylinder, and an exhaust side rocker arm that interlocks and connects the exhaust valve and cam shaft is swingably supported on the exhaust side rocker arm shaft. SOHC type multi-cylinder internal combustion engine.

(2) Related Art Conventionally, in such a SOHC type multi-cylinder internal combustion engine, the spark plug is generally arranged at a position displaced from the center of the ceiling surface of the combustion chamber.

(3) Problems to be Solved by the Invention However, in the above-mentioned conventional one, knocking is likely to occur.
Moreover, in order to insert the spark plug from the side of the cylinder head, it is necessary to build up the periphery of the spark plug on the ceiling surface of the combustion chamber, which makes the shape of the combustion chamber unfavorable.

The present invention has been made in view of the above circumstances, and solves the above problems by disposing an ignition plug in the center of a combustion chamber and enables shortening of the engine body along the axial direction of the camshaft. An object is to provide a SOHC type multi-cylinder internal combustion engine.

B. Configuration of the Invention (1) Means for Solving the Problems According to the present invention, the intake valve and the intake valve are connected to the center of the ceiling surface of the combustion chamber so as to insert the ignition plug into the center of the ceiling surface, and the intake valve and A cylinder portion forming an insertion hole inclined to one side of the exhaust valve is integrally provided with the holder member, and in the cylinder at the outermost end along the axial direction of the cam shaft, the intake air on the side where the cylinder portion is arranged is provided. Side or exhaust side rocker arm is arranged on the inner side of the tubular portion along the axial direction of the cam shaft.

(2) Action The spark plug is disposed so as to face the center of the ceiling surface of the combustion chamber by the insertion hole, and knocking can be prevented. Moreover, in the outermost cylinder along the axial direction of the camshaft, by disposing the rocker arm on the side where the tubular portion is arranged inside the tubular portion, the distance of the cylinder head along the axial direction of the camshaft is increased. It can be shortened to contribute to downsizing of the cylinder head.

(3) Embodiment Hereinafter, an embodiment in which the present invention is applied to a SOHC type four cylinder internal combustion engine will be described with reference to the drawings. First, referring to FIG. 1 and FIG. 2 showing a first embodiment of the present invention, an engine main body will be described. E is provided with a cylinder block 1 and a cylinder head 2 which is superposed on and bonded to the upper portion of the cylinder block 1 via a gasket 3, and is formed in the cylinder block 1 by 4
Pistons 5 are slidably fitted in the respective cylinders 4.
A combustion chamber 6 is defined by the cylinder block 1, the cylinder head 2 and the piston 5, and the ceiling surfaces of the combustion chamber 6 are formed in the shape of a roof facing each other and inclined.

One intake valve port 7 is opened on one side of the ceiling surface of each combustion chamber 6, and an intake port 9 communicating with this intake valve port 7 is bored in the cylinder head 2. Moreover, the intake port 9 is connected to a fuel supply device such as a carburetor via an intake manifold (not shown). On the other side of the ceiling of the combustion chamber 6,
One exhaust valve port 8 is opened, and this exhaust valve port 8 is connected to an exhaust manifold (not shown) via an exhaust port 10 formed in the cylinder head 2.

The cylinder head 2 has an intake valve 11 that opens and closes the intake valve port 7.
And an exhaust valve 12 for opening and closing the exhaust valve port 8 are slidably supported in the vertical direction. Moreover, the intake valve 11 and the exhaust valve 12
Are arranged on both sides of the central axis 13 of the cylinder 4 with their upper ends inclined so that they are away from each other.

Between the intake valve 11 and the exhaust valve 12, a single cam shaft 14 common to each cylinder is rotatably arranged above the combustion chamber 6 and near the central axis 13. This camshaft 14 and intake valve 11
Between the camshaft 14 and the exhaust valve 12, a total of three intake-side rocker arm shafts 15 are fixedly arranged in parallel with the camshaft 14 in a position above the camshaft 14 between the camshaft 14 and the exhaust valve 12. An exhaust side rocker arm shaft 16 common to all the cylinders is fixedly arranged in parallel with the cam shaft 14 at a position above the cam shaft 14.

One intake-side rocker arm shaft 17 per cylinder is swingably supported on each intake-side rocker arm shaft 15. The outer end of each rocker arm 17 is connected to the upper end of each intake valve 11 via an adjuster 19. The slipper surface 20 provided at each inner end is in sliding contact with the intake side valve operating cam 21 of the cam shaft 14.
Further, one exhaust side rocker arm 18 per cylinder is swingably supported on the exhaust side rocker arm shaft 16, and the outer end of each rocker arm 18 contacts the upper end of the exhaust valve 12 via an adjuster 22. The slipper surface 23 provided in contact with each other and slidably attached to the exhaust side valve operating cam 24 of the cam shaft 14 is in sliding contact with the slipper surface 23. Therefore, as the camshaft 14 rotates,
The intake side and exhaust side rocker arms 17, 18 swing around the intake side and exhaust side rocker arm shafts 15, 16, respectively,
The intake and exhaust valves 11 and 12 can be opened and closed in cooperation with the valve springs 25 and 26.

The cam shaft 14 is rotatably supported by a cam holder 31, which is a holder member composed of a lower holder 27 integrally provided on the upper part of the cylinder head 2 and an upper holder 28 connected to the lower holder 27 with bolts 29 and 30. To be done. Moreover, the lower holder 27 is provided integrally with the upper portion of the cylinder head 2 by including the central axis 13 of each cylinder 4 and protruding upward in a plane orthogonal to the axis of the cam shaft 14.

The exhaust side rocker arm shaft 16 is fixedly arranged so as to pass through each upper holder 28, and both ends of the exhaust side rocker arm shaft 16 are located at both ends of the cylinder head 2 along the axial direction of the cam shaft 14.
It is supported by a holder 32 attached to 2a.

The exhaust side rocker arm 18 is swingably supported on the exhaust side rocker arm shaft 16 outside the respective cam holders 31 along the axis of the cam shaft 14, and between the holder 32 and the exhaust side rocker arm 18, and the cam holder. A coil spring 33 surrounding the exhaust side rocker arm shaft 16 is interposed between the exhaust side rocker arm 18 and the exhaust side rocker arm 18 in order to fix the axial position of each exhaust side rocker arm 18.

On the intake valve 11 side of the upper holder 28, there is integrally provided a support portion 35 having a larger axial thickness than the portion supporting the cam shaft 14 and the exhaust side rocker arm shaft 16. The lower holder 27 and the upper holder 28 that form the cam holder 31 are coaxially connected to each other via a seal member 47, and also have a support portion.
A cylindrical portion 37 that forms an insertion hole 36 that extends obliquely from the outer side portion of the combustion chamber 6 toward the center of the ceiling surface of the combustion chamber 6 is integrally provided. A screw hole 38 communicating with the central portion is provided. A spark plug P is inserted into the insertion hole 36, and the spark plug P is screwed into the screw hole 38 so that the tip of the spark plug P faces the center of the ceiling surface of the combustion chamber 6.

In both outermost cylinders along the axis of the camshaft 14, the intake side rocker arm 17 is arranged on the inner side of the cylinder portion 37 along the axis of the camshaft 14, and the inner side along the axis of the camshaft 14. Even in the two cylinders on the side, the intake-side rocker arm 17 is arranged on the inner side of the cylinder portion 37 along the axis of the cam shaft 14. The intake side rocker arm shaft 15 that pivotally supports the intake side rocker arm 17 is
It is fixedly arranged between the bearing portions 35 of the cylinders adjacent to each other. That is, one intake side rocker arm shaft 15 is provided between the bearing portions 35 of the cylinders at both outer ends and the bearing portions 35 of the cylinders that are adjacent to the outer end cylinders on the inner side.
One intake-side rocker arm shaft 15 is provided between the bearing portions 35 of the two inner cylinders. That is, the four intake-side rocker arms 17 are swingably supported by the three intake-side rocker arm shafts 15. A coil spring 34 surrounding the intake-side rocker arm shaft 15 is interposed between each intake-side rocker arm 17 and the support portion 35 so as to fix the axial position of the intake-side rocker arm 17.

The cylinder head 2 has a head cover 40 for covering the valve gear.
Are coupled via a seal member 39, and the head cover 40
A pressing portion 42 that comes into contact with the upper end of the tubular portion 37 via a seal member 41 is integrally provided in the. The pressing portion 42 is provided with a hole 43 continuous with the tubular portion 37, and the hole 43 is closed by a cap 45 provided on a cord 44 connected to the spark plug P so as to be openable and closable.

Next, the operation of this embodiment will be described. When the cam shaft 14 is rotationally driven according to the operation of the engine, the intake side and exhaust side rocker arms 17 and 18 swing around the intake side and exhaust side rocker arm shafts 15 and 16. Move, in cooperation with the valve springs 25, 26,
The intake valve 11 and the exhaust valve 12 are opened and closed at a predetermined timing.

At this time, since the ignition plug P is disposed so as to face the center of the ceiling surface of the combustion chamber 6, the flame propagation distances from the ignition point to the peripheral edges of the combustion chamber 6 are substantially equal, and therefore the combustion time is shortened and the high output is obtained. It is possible to prevent the occurrence of knocking, and it is not necessary to turn a padding on the ceiling surface of the combustion chamber 6.

In addition, the intake side rocker arms are attached at both outer ends along the axis of the camshaft 14.
Since 17 is arranged on the inner side of the cylindrical portion 37, the camshaft
It is possible to shorten the distance between both end portions 2a of the cylinder head 2 and the cylindrical portion 37 along the axis of 14, and it is possible to contribute to downsizing of the engine body E. Moreover, since the intake-side rocker arm shaft 15 is not provided in common for each cylinder, but is provided as a necessary part divided into three,
It can contribute to weight reduction.

FIG. 3 shows a second embodiment of the present invention, in which parts corresponding to those of the first embodiment are designated by the same reference numerals.

The exhaust-side rocker arm shaft 16 'is provided between the holder 32 and the cam holder 31 in the cylinders at the outermost ends along the axis of the cam shaft 14 and between the cam holders 31 of the two cylinders along the axis of the cam shaft 14. To be That is, four exhaust side rocker arms 18 are swingably supported by the three exhaust side rocker arm shafts 16 '.

In addition, in the two cylinders on the inner side along the axis of the camshaft 14, the intake side rocker arm 17 is arranged on the axially outer side of the tubular portion 37, and the intake side rocker arm 17 axially supports the intake side rocker arm 17. The rocker arm shaft 15 'is provided between the bearing portions 35 of the outermost cylinder along the axis of the cam shaft 14 and the cylinder adjacent to the cylinder on the inner side. That is, the four intake side rocker arms 17 are swingably supported by the two intake side rocker arm shafts 15 '. Moreover, the web washers 48 are respectively interposed between the intake side rocker arms 17 adjacent to each other.

According to this embodiment, the same effect as that of the first embodiment can be obtained, and the weight can be further reduced.

In the above embodiments, the case where the tubular portion 37 is provided on the intake valve 11 side has been described.
It is also possible to provide 31. In the above embodiment, the cam shaft 14 and the rocker arm shafts 15, 16 are supported by the cam holder 31, but a holder member for supporting the rocker arm shafts 15, 16 is provided separately from the cam holder for supporting the cam shaft 14. The present invention can also be applied to the products.

C. Effects of the Invention As described above, according to the present invention, either one of the intake valve and the exhaust valve is connected to the center of the ceiling surface of the combustion chamber so as to insert the spark plug and is connected to the center of the ceiling surface and goes upward. In the cylinder at the outermost end along the axial direction of the cam shaft, the cylinder portion forming the inclined insertion hole is integrally provided with the holder member, and the intake side or exhaust side rocker arm on the side where the cylinder portion is arranged has the cam portion. Since it is arranged on the inner side of the cylinder along the axial direction of the shaft, the spark plug can be arranged at the center of the ceiling surface of the combustion chamber to prevent knocking, and the cylinder is provided. As a result, it is possible to avoid increasing the length of the cylinder head along the axial direction of the cam shaft, which contributes to downsizing.

[Brief description of drawings]

1 and 2 show a first embodiment of the present invention. FIG. 1 is a vertical side view, FIG. 2 is a plan view of FIG. 1 with a head cover removed, and FIG. It is a top view corresponding to FIG. 2 of the 2nd Example of this invention. 6 ... Combustion chamber, 14 ... Cam shaft, 15, 15 '... Intake side rocker arm shaft, 16, 16' ... Exhaust side rocker arm shaft, 17 ...
… Intake side rocker arm, 18 …… Exhaust side rocker arm, 31
...... Cam holder as holder member, 36 …… Insertion hole, 37
…… Cylinder, P …… Spark plug

Claims (1)

[Claims] 1. A spark plug is disposed facing a ceiling surface of a combustion chamber, and intake and exhaust side rocker arm shafts are holder members on both sides of a single cam shaft rotatably disposed above the combustion chamber. The intake side rocker arm shaft has an intake side rocker arm that links and connects one intake valve and cam shaft per cylinder, and the exhaust side rocker arm shaft also links and connects the exhaust valve and cam shaft. In a SOHC type multi-cylinder internal combustion engine in which each side rocker arm is swingably supported, in order to insert a spark plug into the central portion of the ceiling surface of the combustion chamber, the intake valve and exhaust valve A cylinder portion that forms an insertion hole that is inclined to one side is integrally provided in the holder member, and in the cylinder at the outermost end along the axial direction of the cam shaft, the intake side cylinder on the side where the cylinder portion is arranged is located. The SOHC type multi-cylinder internal combustion engine is characterized in that the rocker arm on the exhaust side is arranged on the inner side of the cylinder portion along the axial direction of the camshaft.