Internal combustion engine for natural gas compressor operation

A method, comprising:

• supplying a fuel gas to a bimodal piston-cylinder assembly of an internal combustion engine from a fuel gas source, the bimodal piston-cylinder assembly including a piston configured to travel in a cylinder and being operable in a compression mode to compress fuel gas in the cylinder with alternating intake and compression strokes of the piston without combusting the fuel gas, and in a combustion mode to receive fuel gas for combustion in the cylinder as fuel, the bimodal piston-cylinder assembly being fluidly connected to a first pressure tank and a second pressure tank;
• compressing fuel gas supplied from the fuel gas source in the bimodal piston-cylinder assembly with the piston such that compressed fuel gas flows into the first and second pressure tanks;
• supplying compressed fuel gas from the first pressure tank to the bimodal piston-cylinder assembly when the first and second pressure tanks reach a predetermined pressure;
• and further compressing the compressed fuel gas in the bimodal piston-cylinder assembly with the piston such that compressed fuel gas flows into the second pressure tank at a pressure higher than the predetermined pressure.

A reciprocating internal combustion engine configured to compress natural gas for storage onboard an automobile, comprising:

• a plurality of piston-cylinder assemblies including a piston configured to travel in a cylinder, at least one of the piston-cylinder assemblies being a bimodal piston-cylinder assembly operable to receive natural gas for combustion in the cylinder as fuel when operating in a combustion mode, and to compress natural gas in the cylinder with alternating intake and compression strokes of the piston without combusting the natural gas to provide compressed natural gas when operating in a compression mode;
• a cylinder head located above the plurality of piston-cylinder assemblies, the cylinder head including at least one intake valve and at least one exhaust valve in fluid communication with each respective piston-cylinder assembly, the intake valves being configured to supply a natural gas fuel-air mixture to the respective piston-cylinder assemblies before a combustion stoke of the respective pistons, the exhaust valves being configured to exhaust combustion gases from the respective piston-cylinder assemblies after the combustion stroke of the respective pistons;
• and one or more compressor valves located in the cylinder head in fluid communication with the bimodal piston-cylinder assembly and with at least one pressure tank through a manifold in the cylinder head.