A multifuel internal combustion Stirling engine for producing power from combustion of fuels, and comprising:
- an engine cylinder, comprising a gas cylinder head at one end of said cylinder, and further comprising an exhaust port, an air port, an air transfer port, and a burned gas port;
- said exhaust port opening into said engine cylinder, and being located at the gas cylinder head end of said engine cylinder;
- said burned gas port opening into said engine cylinder, and being located at the gas cylinder head end of said engine cylinder;
- a displacer piston, operative within said engine cylinder, and comprising:
- a displacer piston gas crown at that end of said displacer piston facing said gas cylinder head, and said cylinder volume between said displacer piston gas crown and said gas cylinder head comprising a gas volume;
- a compressor piston, sealably operative within said engine cylinder, and comprising:
- a compressor piston air crown at that end of said compressor piston facing said displacer piston;
- said displacer piston further comprising a displacer piston air crown at that end of said displacer piston facing away from said gas cylinder head and facing said compressor piston, and said cylinder volume between said displacer piston air crown and said compressor piston air crown comprising an air volume;
- compressor driver means for driving said compressor piston to move back and forth, within said engine cylinder, through a variable compressor piston displacement volume, on said air chamber side of said compressor piston, and so that said variable compressor piston displacement volume is a minimum of zero when said compressor piston is closest to said gas cylinder head, and is a maximum when said compressor piston is furthest away from said gas cylinder head;
- the length of said back and forth motion of said compressor piston being the compressor piston stroke length;
- said air intake port opening into said engine cylinder and being located along that portion of said engine cylinder through which said compressor piston moves back and forth, and further being located so that said air intake port is fully uncovered by said compressor piston when said variable compressor piston displacement volume is a maximum;
- said air transfer port opening into said engine cylinder, and being located beyond that portion of said engine cylinder through which said compressor piston moves back and forth, in the direction of said gas cylinder head;
- the distance between said burned gas port, and said air transfer port, being greater than the length of said displacer piston, between the gas side of said displacer piston gas crown, and the air side of said displacer piston air crown;
- a divided combustion chamber, comprising an inlet connected to said air transfer port, and a gas outlet connected to said burned gas port, and further comprising a burner air channel and a separate bypass air flow channel;
- an exhaust passage connected to said exhaust port, and comprising an exhaust valve with actuator means for opening and closing said exhaust passage;
- exhaust valve driver means for opening and closing said exhaust passage, so that said exhaust passage is opened somewhat before said compressor piston uncovers said air intake port while moving away form said gas cylinder head, and so that said exhaust passage is subsequently closed somewhat after said compressor piston commences moving toward said gas cylinder head;
- displacer driver means for driving said displacer piston to move through a displacer piston variable swept volume cycle, comprising the following sequence of time periods and displacer piston motions in time order;
- a gas transfer time period during which the displacer piston moves toward the compressor piston, and increases said burned gas volume from a minimum value and decreases said air volume;
- said gas transfer time period commencing somewhat before said variable compressor piston displacement volume reaches a minimum value on said air chamber side of said compressor piston;
- said displacer piston motion, in combination with said compressor piston motion, during said gas transfer time period, causing gas to transfer from said air volume into said combustion chamber, via said combustion chamber air inlet;
- said gas transfer time period ending somewhat after said variable compressor piston displacement volume passes said minimum value on said air chamber side of said compressor piston, and when said displacer piston motion has moved the displacer piston air crown past said air transfer port in a direction away from said gas cylinder head;
- an expansion time period during which the displacer piston continues to move toward said compressor piston, and further increases said gas volume, said expansion time period following next after said gas transfer time period;
- said expansion time period ending when said exhaust passage is opened somewhat before said compressor piston has passed said air inlet port, in a motion direction away from said gas cylinder head;
- a scavenge time period during which the displacer piston motion reverses from first continuing to move toward said compressor piston, to next moving rapidly away from said compressor piston;
- said scavenge time period commencing when said exhaust passage is opened and ending when said compressor piston has again passed said air inlet port, in a motion direction toward said gas cylinder head;
- a compression time period during which the displacer piston essentially stops moving and said gas chamber volume remains essentially constant at its minimum value;
- said compression time period following next after said scavenge time period, and ending when said compressor piston motion, toward said gas cylinder head, stops when said variable compressor piston displacement volume reaches a minimum value on said air chamber side of said compressor piston;
- said displacer piston variable swept volume cycle being repeated, concurrently with said back and forth motion of said compressor piston through said variable compressor piston displacement volume;
- said compressor driver means and said displacer piston driver means additionally operating, concurrently relative to each other, so that the volume of said air volume is always greater than zero;
- said displacer piston driver means additionally operating relative to said gas cylinder head, so that the volume of said gas volume is always greater than zero;
- a source of engine fuel;
- fuel transfer means for transferring engine fuel from said engine fuel source into said burner air flow channel of said combustion chamber, so that said engine fuel is contacted with that air portion transferring through said burner air flow channel from said combustion chamber air inlet toward said combustion chamber gas outlet, during said gas transfer time period;
- igniter means for igniting fuel and air within said combustion chamber during said gas transfer time period;
- whereby said internal combustion Stirling engine carries out a power producing engine cycle, while operating through each said displacer piston variable swept volume cycle, the work input of compression, during said compression time period, being less than the work output of expansion, during said expansion time period, since occurrence of combustion, during said gas transfer time period, increases expansion pressures above compression pressures;
- these power producing cycles are repeated by discarding the burned gases to exhaust and refilling the engine cylinder with air during each scavenge time period.