Dual fuel natural gas/diesel 2-stroke engine

Claim 1

In a dual fuel, natural gas/diesel two-stroke engine having 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, the improvement according to which the gas injection means includes 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.

Claim 8

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).

Claim 9

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).