Dual fuel natural gas/diesel 2-stroke engine

A duel fuel, natural gas/diesel two stroke engine comprising:

• at least one cylinder,
• a piston in the cylinder,
• inlet port means around the cylinder to be uncovered by downward movement of the piston in the cylinder,
• air means for forcing air through said inlet port means when uncovered,
• an exhaust port and valve means for opening said exhaust port once each cycle to exhaust combustion gases from said cylinder,
• diesel injection means to inject diesel fuel into the cylinder once each cycle,
• and gas injection means for injecting natural gas into the cylinder once each cycle, said gas injection means including a delivery conduit for natural gas, which conduit opens into the cylinder at a location above said inlet port means, whereby the piston when descending completely uncovers said conduit before beginning to uncover said inlet port means.

A method of operating a dual fuel, natural gas/diesel two stroke engine, the engine comprising:

• at least one cylinder,
• a piston in the cylinder,
• inlet port means around the cylinder positioned to be uncovered by downward movement of the piston in the cylinder,
• air means for forcing air through said inlet port means when uncovered,
• an exhaust port and valve means for opening said exhaust port once each cycle to exhaust combustion gases from said cylinder,
• diesel injection means to inject diesel fuel into the cylinder once each cycle,
• and gas injection means for injecting natural gas into the cylinder once each cycle, said gas injection means including a delivery conduit for natural gas, which conduit opens into the cylinder at a location above said inlet port means, whereby the piston when descending completely uncovers said conduit before beginning to uncover said inlet port means;
• said method comprising the steps:
• a) as the piston approaches top dead center, injecting diesel fuel into the cylinder to initiate combustion of an ignitable gaseous mixture previously placed in the cylinder,
• b) as the piston descends on the power stroke, beginning the opening of the exhaust port and initiating exhaust prior to the point where the descending piston uncovers the said conduit,
• c) uncovering the conduit due to the further descent of the piston,
• d) after the descending piston has uncovered said inlet port means, forcing air into the cylinder,
• e) after the descending piston has passed bottom dead centre initiating injection of natural gas into the cylinder,
• f) after the ascending piston covers inlet port means, ceasing the forcing of air into the cylinder,
• g) closing the exhaust port, as the piston closes the inlet port means,
• h) halting the injection of natural gas before the ascending piston covers said conduit, but after the piston has closed said inlet port means,
• i) closing the said conduit after halting the injection of natural gas, and
• retracing steps a) through i).