High efficiency steam engine, steam expander and improved valves therefor

A steam expander of an engine comprising:

• at least one engine cylinder having a cylinder head and a working piston slideably mounted therein and operatively related to a crankshaft for imparting rotation to the crankshaft;
• a steam inlet valve;
• wherein the steam inlet valve further comprises an inlet valve body that is slideably mounted within a valve bore in the cylinder head of the engine;
• the valve body having a valve closure surface for contact with a valve seat when moved axially in the valve bore;
• said expander having a steam expansion chamber between the working piston and the valve body;
• wherein the valve body has a valve face on a free end thereof that confronts the working piston for establishing face-to-face contact therewith;
• wherein the steam expander has a steam supply passage for introducing steam into the steam expansion chamber when the valve body is raised off of the valve seat;
• wherein the face on the free end of the valve body is located to contact the working piston throughout the area of an end of the working piston to thereby enhance a reduction of the clearance volume between the steam cylinder head and the working piston as a bump force from working piston motion moves the valve body off of the valve seat;
• wherein the engine is devoid of a lifter element projecting from either the inlet valve or piston for operative interaction therebetween and
• wherein a valve bore diameter for the steam inlet valve body is at least as large as a diameter of the engine piston whereby the engine piston moves the inlet valve in a direction to open the inlet valve.

An engine having a Rankine cycle steam expander therein for transmitting power to a crankshaft comprising:

• at least one engine cylinder having a steam cylinder head and a working piston slidably and sealingly mounted in the at least one engine cylinder with a steam expansion chamber therein having a cylindrical side wall and two ends and the piston being operatively connected to a crankshaft for imparting rotation thereto,
• a steam inlet valve having a valve body that is slidably mounted in a bore in the steam cylinder head and having a face at a free end thereof that forms all of an end of the expansion chamber confronting the working piston,
• wherein the valve body of the steam inlet valve is yieldably biased by a first relatively strong biasing force to seal a valve seat in the engine that surrounds both the inlet valve face and a port that communicates between the bore and the expansion chamber,
• wherein the valve body of the steam inlet valve has a sidewall positioned to reciprocate within the bore in the steam cylinder head during operating for admitting steam when moved away from the expansion chamber and off of the valve seat,
• wherein the entire face of the inlet valve contacts one end of the expansion chamber defined by the working piston to enhance a reduction of engine clearance volume within the at least one engine cylinder at an end of an exhaust stroke,
• wherein a steam exhaust valve that has a face on a free end thereof that forms a portion of a top of the working piston and the steam exhaust valve is yieldably urged toward an open position by a second biasing force that is less than the first biasing force,
• wherein the exhaust valve is closed by contact with the face of the inlet valve,
• wherein confronting surfaces associated with the working piston and the steam inlet valve come into contact with one another as piston motion applies a bump force to the steam inlet valve,
• wherein the relationship between the first and second biasing forces causes the steam exhaust valve to close at or before the opening of the steam inlet valve,
• wherein the steam inlet valve is at least as large in diameter as the working piston and contact between the working piston and the inlet valve produces a zero clearance throughout the cross-sectional area of the working piston as the bump force applied by working piston motion elevates the inlet valve off of the inlet valve seat,
• such that the working piston opens the inlet valve by imparting movement to the inlet valve, and
• such that clearance in the expansion chamber is reduced thereby reducing residual steam remaining in the expansion chamber as the working piston in the at least one engine cylinder reaches a dead center position between a power stroke and an exhaust stroke.