JP2534274Y2 - Decompression device for four-cycle 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 decompression device for a four-valve four-cycle engine in which one cylinder is provided with two intake valves and two exhaust valves.

[0002]

2. Description of the Related Art In a four-cycle engine, when the engine is started, the intake air in the cylinder is released by a decompression device, the compression pressure is reduced, and the crankshaft rotates lightly. Then, the decompression device is released, and the operation is started by starting with a normal compression pressure.

[0003] As a four-stroke engine, there is a four-valve engine in which one cylinder is provided with two intake valves and two exhaust valves. In this four-valve engine, as shown in FIG. 5, the tip of an intake rocker arm A having a forked tip is applied to the upper ends of two intake valves, and the intake rocker arm A is swung by an intake cam C of a cam shaft B. Thus, the two intake valves are pushed open against the valve spring. The decompression cam E is brought into contact with one side of the rocker face D of the intake rocker arm A, and the decompression cam E pushes and opens two intake valves with the intake rocker arm A to decompress.

[0004]

[Problem to be solved by the invention] Intake rocker arm A
The contact surface between the rocker face D and the decompression cam E cannot be made sufficiently large due to space. On the other hand, the decompression cam E pushes and opens the two intake valves against the valve springs of the two intake valves, so that the surface pressure on the sliding surface between the decompression cam E and the rocker face D increases, and the inconvenience of easy wear is increased. is there.

[0005] In view of such a point, the present invention provides a four-valve engine, in which one intake rocker arm pushes and opens two intake valves, and one intake valve is pushed and opened by a decompression arm to decompress. It is an object of the present invention to obtain a four-cycle engine decompression device that has high durability and can be operated easily.

[0006]

In order to achieve the above object, a decompression device for a four-stroke engine according to the present invention is provided.
An intake rocker arm with a forked tip that swings the intake rocker arm with the intake cam of the camshaft to push open two intake valves.The upper end of one intake valve and the tip of the intake rocker arm The end of the decompression arm is inserted between them, and at the time of starting, only one intake valve is pushed open by the decompression cam via the decompression arm to decompress.

[0007]

When decompressing at the start, only one of the intake valves is pushed and opened against the valve spring via the decompression arm with the decompression cam to decompress. Since the other intake valve does not decompress, the reaction force of the valve spring applied to the decompression arm and the decompression cam becomes half that of only one of the intake valves. For this reason, the durability of the decompression cam is improved, and the operating force can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The intake rocker arm 1 and the exhaust rocker arm 2 are each pivotally supported on a rocker shaft 3. The arm 2 is swung. The camshaft 4 rotates in conjunction with a crankshaft with a chain or the like. The intake rocker arm 1 has a bifurcated tip, and two intake valves 7 are arranged side by side to push down and open the intake valve 7 against the valve spring 8.

Thus, a decompression arm 9 pivotally supported on the rocker shaft 3 is provided, and the tip of the decompression arm 9 is inserted between the upper end of one intake valve 7 and the tip of the intake rocker arm 1. The base end of the decompression arm 9 is applied to the decompression cam 10.

At the time of starting, the decompression arm 9 is swung by the decompression cam 10, and one of the intake valves 7 is depressed and opened against the valve spring to decompress. During normal operation, the decompression cam 10 is detached, the decompression arm 9 becomes free, and the decompression arm 9 follows the movement of the intake rocker arm 1.

[0011]

As described above, since the present invention is constructed as described above, one intake rocker arm simultaneously pushes open two intake valves, and the upper end of one intake valve and the intake rocker are opened. The distal end of the decompression arm is inserted between the distal ends of the arms, and only one of the intake valves can be pushed open by the decompression cam through the decompression arm to perform decompression. For this reason, the valve spring applied to the decompression cam is reduced to half for only one intake valve,
The durability of the decompression cam increases and the operating force can be reduced. In addition, the decompression arm and the decompression cam can be made into parts having different functions, so that the strength can be maintained and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a vertical sectional front view showing the embodiment of the present invention.

FIG. 3 is a plan view of the decompression arm alone showing the embodiment of the present invention.

FIG. 4 is a front view of the decompression arm alone showing the embodiment of the present invention.

FIG. 5 is a plan view showing a conventional decompression device.

[Explanation of symbols]

 Reference Signs List 1 intake rocker arm 4 camshaft 5 intake cam 7 intake valve 9 decompression arm 10 decompression cam

Claims (1)

(57) [Scope of request for utility model registration] 1. An intake rocker arm having a forked tip, wherein the intake rocker arm is swung by an intake cam of a camshaft to open and open two intake valves.
The tip of the decompression arm is inserted between the upper end of one intake valve and the tip of the intake rocker arm, and at the time of starting, only one intake valve is pushed open via the decompression arm with the decompression cam to decompress. A decompression device for a four-cycle engine.