Piston engine comprising member to cover bottom face of valve head of poppet valve

Abstract

To achieve high compression ratio and lower temperature of the exhaust poppet valve in an engine provided with a poppet valve on an extend part of a combustion chamber outside a main cylinder, disclosed is a valve cover having a cylindrical side face and upper face, an compression ring either the cylindrical side face and an inner wall of the sub cylinder, means to contact closely a bottom face of a poppet valve and the upper face of the valve cover, the upper part of the valve cover occupying most part of the combustion chamber facing with the bottom face, the valve cover moves along with the poppet valve when the poppet valve is lifted, a combination of overhead valves and the poppet valve including one intake valve and one exhaust valve, and total number of the overhead valve and poppet valve is not less than 3.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a piston engine comprising a member to cover a bottom face of a valve head of a poppet valve. When the combustion chamber extends outside the main cylinder, the member occupies a space facing with the bottom face of the poppet valve provided outside a main cylinder in a combustion chamber.[0003]2. Description of the Related Art[0004]The suction resistance and exhaust resistance of a four cycle engine are high when it rotates at high speed. The suction lifts in this engine are extremely small in the initial stages of the periods when the suction valve is open. The initial stages are shorter when the engine rotates at a higher speed. This restricts the inflow of suction gas. As a result, in the initial stages of the periods when the suction valve is open, the pressure in the cylinder is lower than the pressure at the back of the piston.[0005]Under this condition, the piston keeps moving do...

AI Technical Summary

Benefits of technology

[0025]A second object is to lower a temperature of the valve when it is used as an exhaust valve.

[0058]Further, a total area of the intake and exhaust valves of the engine according to the three aspects of the present invention is larger than engines provided with overhead valves only in a main cylinder. Therefore, intake and exhaust resistance reduces especially when rotating at high speed. Output power of the engine of the invention thus can increase.

Problems solved by technology

As a result, the negative work increases.

This increases the loss caused by the suction resistance, so that the torque lowers.

As a result, just after the piston leaves the bottom dead point, the exhaust resistance causes a great loss.

Consequently, the combustion chamber having a suction valve facing the top of the piston and a side valve cannot have a high combustion ratio, so that the engine efficiency is low.

As a result, knocking occurs.

If the strokes of the piston are longer than its diameter, the combustion gas conversion efficiency is high, but the suction efficiency is low when the engine rotates at high speed.

The low suction efficiency leads to low torque.

If the piston strokes are shorter than the piston diameter, the suction efficiency is high when the engine rotates at high speed, but the combustion gas conversion efficiency is low.

Therefore, long strokes of the pistons of conventional spark ignition engines have been incompatible with torque increases that may be caused when the engines rotate at high speed.

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