Patent GB-1418489-A (GB)
Title: Pre-combustion chamber internal combustion engines
IPC: F02B19/10
Filed: 1972-12-09
Abstract: 1418489 Pre-combustion chamber IC engines THERMO ELECTRON CORP 9 Dec 1972 57105/72 Heading F1B [Also in Division G3] Fuel is delivered directly to the pre-combustion chamber 52 in each engine cycle, two or fourstroke, and the pressure applied to the fuel to be delivered is constant or substantially constant at least during the cycle. The applied pressure is in excess of the pressure in the pre-combustion chamber over a period in each engine cycle, e.g. during exhaust and charging of the main combustion chamber 56, and fuel is delivered to the pre-combustion chamber over at least part of the period at a rate dependent upon the difference between the fuel and pre-combustion chamber pressures. Fuel-air mixture or fuel and air separately are supplied to the main combustion chamber. In the embodiment shown an engine driven pump 196 supplies fuel at a rate proportional to engine speed to manifolds 132 and 150 connected respectively to the four chambers 52 and the intake passages of the four chambers 56. The flow of fuel to the manifold 150 is controlled by an adjustable throttle 148 and the valve 208 controlling fuel return from the pump 196 to the tank 202 is preferably adjusted so that the pressure of fuel in the manifold 132 is such that with the throttle 148 closed sufficient fuel is fed to the chambers 52 to operate the engine at idling. Increasing opening of the throttle 148 increases the fuel supply to the chambers 56 and the resulting fall in pressure in the manifold 132 causes the fuel supply to the chambers 52 to be reduced. The manifold 132 is connected to the chambers 52 through spring-biased ball non-return valves 164 and fuel lines (166a), Fig. 3 (not shown), having a diameter to length ratio considerably less than 1, e.g. 0.0003, and fuel is injected into the chambers 52 over substantially the complete period of each cycle during which the fuel pressure exceeds the pre-combustion chamber pressure. In another embodiment, Fig. 5 (not shown), fuel is supplied at a constant pressure by an electrically-driven pump (262) to solenoid-operated injectors (252 and 254) supplying the pre- and main combustion chambers. The injectors include check valves so that fuel can be injected only when the fuel pressure exceeds the pressure in the associated chamber. The solenoids are operated by a control circuit (274) receiving signals from a pulse generator (278) in accordance with engine speed. The control circuit is adjusted by the operator to vary the timing or duration of opening of the injectors. There is a separate control circuit for each cylinder of a multi-cylinder engine. The precombustion chamber injectors (252) are opened at a constant crank angle for a time period which varies with load but not speed. The main chamber injectors (254) may be opened by the solenoids at a constant crank angle for an operator controllable period or the valves may be opened for the same period in each engine cycle with operator control of the relationship between the timing of the period of opening and the end of the period over which the combustion chamber pressure is below the fuel pressure. The control may be provided by a variable delay circuit or an R-C network having a variable time constant. For over-running the injectors (252, 254) may remain closed to terminate fuel injection. The engine may be a rotary piston engine.