JPS603925Y2 - Internal combustion engine decompression device - Google Patents

Description

[Detailed description of the invention] The present invention is a device for lifting an exhaust valve to remove compression in order to make rotation easier when starting an internal combustion engine.
This is usually referred to as a decompression device.

Various types of such decompression devices have been proposed in the past.

For example, engaging a cam at one end of the rocker arm of an engine exhaust valve (the end opposite to the end engaged by the bushing rod);
The exhaust valve is held open by rotating this cam when the engine is started, or a collar is provided in the middle of the bushing rod of the exhaust valve, and a decompression cam is provided to engage with this collar. A decompression lever is installed on the rocker arm shaft of the exhaust valve.
-43944) etc.

However, these have the following drawbacks.

In other words, in the first example above, the shaft of the decompression cam is often installed on the bonnet of the engine, and in such cases, the bonnet must be removed during engine maintenance (for example, to adjust the valve gap). Sometimes the decompression operation becomes impossible.

Furthermore, in the second example, the space surrounding the bushing rod is too large to be used in small engines.

Furthermore, in the third example, the structure of the rocker arm shaft is complicated.

The present invention is an attempt to eliminate the above-mentioned drawbacks of conventional decompression devices, and the present invention aims to eliminate the above-mentioned drawbacks of conventional decompression devices. A rotary shaft 6 having a protruding collar 9 and an eccentric portion 10 that engages with the lower surface of the annular collar 9 is rotatably supported on the outer surface of the cylinder block 1, and the outer end of the rotary shaft 6 is operated. The feature is that the lever 7 is fixedly installed.

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

In the figure, a tappet 4, which constitutes a part of an exhaust valve device, is fitted and supported in a cylinder block 1 so as to be able to reciprocate, and the tappet 4 comes into sliding contact with a cam 3 of a camshaft 2 at its bottom surface.

5 is a bushing rod of an exhaust valve (not shown).

An annular collar 9 that extends outward is integrally protruded from the upper end of the tappet 4, and the collar 9 has an eccentric portion 10 (this portion has a semicircular cross section) of the rotating shaft 6, which has an eccentric portion on the lower surface. shape, and its flat portion contacts the lower surface of the collar 9 at a small distance), with a small distance 1 between them.

The rotating shaft 6 is pivotally supported by the cylinder block 1, and an operating lever 7 is fixed to the outer end of the rotating shaft 6.

8 is a stopper of the operating lever 7.

During normal operation of the engine, the eccentric portion 10 of the rotating shaft is located at the collar 9.
Since the rotating shaft 6 does not directly contact the lower surface of the engine, the presence of the rotating shaft 6 has no effect on the engine.

When starting the engine, the operating lever 7 is rotated and the rotating shaft 6 is rotated approximately 90' to 180 degrees.

By doing so, the eccentric portion 10 of the rotating shaft 6 lifts the collar 9 by an eccentric amount S', and as a result the exhaust valve is pushed down via a rocker arm (not shown), releasing the compression of the engine ( In other words, it will be decompressed).

According to the present invention, since the eccentric portion 10 of the rotating shaft 6 having the operating lever 7 fixed to the outer end is engaged with the lower surface of the annular collar 9 of the tappet 4, the decompression operation of the engine can be performed easily. This can be easily done by rotating the operating lever 7.

Furthermore, since the collar 9 is an annular collar that expands outward, a predetermined displacement can be applied to the tappet 4 no matter where the eccentric portion 10 engages with the lower surface of the collar 9. Thereby, there is no risk that a specific portion of the lower surface of the collar 9 will be worn out due to engagement with the eccentric portion 10, resulting in uneven displacement.

Further, by providing an annular collar 9 that expands outward at the upper end of the tappet 4, it is possible to prevent the tappet from falling off when the camshaft is removed.

Also, a rotating shaft 6 having an operating lever 7 and an eccentric portion 10 is provided.
Since it is pivotally supported on the outer surface of the cylinder block 1 of the engine, it can be operated even when the bonnet is removed, such as during engine repair work.

In addition, since the eccentric portion 10 of the rotating shaft 6 and the collar 9 that engages with the eccentric portion 10 of the rotating shaft 6 are located in the space around the upper end of the tappet 4, there is no risk of increasing the overall size, and the structure is extremely simple, making it easy to manufacture. This is easy and there is no risk of cost increase.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a side sectional view of a decompression device according to the present invention, and FIG. 2 is a sectional view taken along the line A--A in FIG. 1. 1... Cylinder block, 2... Camshaft, 3... Cam, 4... Tappet, 5...
...Butsch rod, 6... Rotation shaft, 7
...Lever, 8...Stopper, 9...
...Brim, 10...Eccentric part.

Claims (1)

[Scope of utility model registration request] An annular flange 9 extending outward is protruded from the upper end of the tappet 4 constituting an exhaust valve device of an internal combustion engine, and a rotating shaft 6 having an eccentric portion 10 that engages with the lower surface of the annular flange 9 is attached to a cylinder block. A decompression device for an internal combustion engine, which is rotatably supported on the outer surface of a rotary shaft 6 and has an operating lever 7 fixed to the outer end of the rotating shaft 6.