JPH0472966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve train for a double overhead cam type internal combustion engine having a pair of camshafts.

(Prior Art) Generally, in a valve train in which a camshaft drives a plurality of valve stems arranged radially in a combustion chamber, it is difficult for the pressing direction of the Rocker arm to match the axial direction of the valve stem. A sub-rocker arm is interposed between the valve stem and the valve stem, thereby pressing the valve stem in the axial direction.

(Problem to be Solved by the Invention) By the way, it is preferable to make the angle of the valve as small as possible in order to reduce the intake and exhaust resistance. In the case where the valve stems are arranged side by side, it is desirable to arrange each valve stem so that its stem end is located closer to the center of the combustion chamber with respect to each camshaft, thereby reducing the angle between the valves. In addition, when each valve stem is driven by each camshaft via the rocker arm and the sub rocker arm as described above, the rocker arm shaft should be moved to the valve stem so that the contact point with the sub rocker arm does not shift significantly laterally when the rocker arm swings. It is preferable to arrange it as far away from the end as possible, and when the stem end is located near the center of the combustion chamber with respect to the camshaft as described above, the rocker armshaft should be placed on the opposite side of the camshaft from the stem end, that is, It is desirable to place it closer to the outside.

However, when the rocker arm shaft is arranged in this way, it is necessary to form a bearing hole for the shaft in the outer part of the cylinder head, and in this case, the shaft of the sub rocker arm must be formed in the outer part of the cylinder head. Since it is also necessary to form a bearing hole for the sub-rocker arm shaft for insertion and support from the outer surface of the head, both bearing holes intersect, which tends to reduce the rigidity of the cylinder head.

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve train that satisfies the above-mentioned needs and also ensures the rigidity of the cylinder head.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a valve train for a double overhead cam type internal combustion engine having a pair of camshafts, which are arranged radially in a combustion chamber. In a device in which a plurality of valve stems are linked to each camshaft via a rocker arm and a subrocker arm, each valve stem is arranged so that its stem end is located closer to the center of the combustion chamber with respect to each camshaft, The shaft of each rocker arm is arranged so as to be located on the opposite side of the stem end with respect to each camshaft, and the shaft of the sub rocker arm is arranged parallel to a plane perpendicular to the shaft of the rocker arm. shall be.

(Function) By placing the valve stem closer to the center of the combustion chamber with respect to the camshaft, the angle of the valve is reduced, reducing intake and exhaust resistance.On the other hand, the Rotsuker armshaft is placed opposite the stem end to the camshaft. By providing it on the side, the distance from the rocker arm shaft to the contact point of the tip of the rocker arm with the sub rocker arm becomes longer, and the amount of lateral shift of the contact point can be suppressed to a small value.

In addition, even if the bearing hole of the rocker arm shaft and the bearing hole of the sub rocker arm shaft intersect, the two bearing holes are perpendicular to each other, making machining easier and minimizing the volume of the intersection, which reduces the rigidity of the cylinder head. There's nothing to lose.

(Example) In the figure, 1 is a cylinder, 2 is a cylinder head, and the combustion chamber of the cylinder head 2 is connected to the intake valve 3.
A double overhead cam type internal combustion engine is constructed by providing two camshafts 10 and 4, and a pair of camshafts 10, 10 arranged side by side on the cylinder head 2.

Valve stems 3a and 4a of the intake and exhaust valves 3 and 4
are arranged radially with respect to the combustion chamber, and each rocker arm 6 is interlocked with each camshaft 10.
is brought into contact with each stem end of each valve stem 3a, 4a via each sub-rocker arm 5, and the intake and exhaust valves 3, 4 are driven to open and close.

Each valve stem 3a, 4a is arranged so that its stem end is located closer to the center of the combustion chamber with respect to each camshaft 10, in order to reduce the angle between the valves 3, 4. One rocker arm shaft 7 is provided for each camshaft 10, located on the opposite side of the stem end, that is, on the outside, and inserted into and supported by a bearing hole formed in the cylinder head 2. a pair of rocker arms 7 interlocked with the camshaft 10,
7 was pivoted at its tail end.

Further, each sub-rocker arm 5 is pivotally supported by a different sub-rocker arm shaft 8 arranged parallel to a plane perpendicular to the rocker arm shaft 7, and the rocker arm 5 is mounted on an outer portion of the cylinder head 2. A bearing hole for a sub-rocker arm shaft 8 is formed perpendicularly intersecting the bearing hole for the arm shaft 7, and the shaft 8 is connected to the cylinder head 2.
Pass the cylinder head 2 through the bearing hole from the outer surface side of the cylinder head 2.
The tip of the shaft 8 is fitted into a recess formed in the peripheral wall of the plug insertion hole in the center of the cylinder head 2, and the shaft 8 is inserted into the spring 9.
The rocker arm shaft 7 is urged outwardly so that its tail end comes into contact with the circumferential surface of the rocker arm shaft 7, and the shaft 8 is supported in the cylinder head 2 with both ends supported.

In the figure, 11 is a valve spring, 12 is an adjustment screw at the tip of the rocker arm 6, and 13 is a head cover.

(Effects of the Invention) As is clear from the above description, according to the present invention, it is possible to reduce the intake and exhaust resistance by reducing the angle of the valve, and also to reduce the amount of lateral deviation of the contact point of the rocker arm with respect to the sub rocker arm. This improves the operating performance of the internal combustion engine, and since the shaft bearing holes of the rocker arm and subrocker arm are perpendicular to each other, machining becomes easier, and the volume of the intersection of the bearing holes is reduced as much as possible. By reducing this, the rigidity of the cylinder head can also be ensured.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a partially cutaway front view, and FIG. 2 is a plan view of the main part. 3a...Valve stem, 4a...Valve stem, 5...Subrotsuker arm, 6...Rotsuker arm, 7...Rotsuker arm shaft, 8...
Subrock car armshaft, 10...camshaft.

Claims (1)

[Claims] 1. A valve operating system for a double overhead cam type internal combustion engine having a pair of camshafts, in which a plurality of valve stems arranged radially in the combustion chamber are linked to each camshaft via a rocker arm and a subrocker arm, respectively. in which each valve stem is arranged so that its stem end is located near the center of the combustion chamber with respect to each camshaft, and the shaft of each rocker arm is located on the opposite side of each camshaft from the stem end. A valve train for an internal combustion engine, characterized in that the shaft of the sub rocker arm is arranged parallel to a plane perpendicular to the shaft of the rocker arm.