Two-phase lpg fuel supply

Abstract

A fuel supply system for propane and other LPG fuels is disclosed for internal combustion engines such as spark-ignited direct-injection (SIDI) engines, with features that help manage both liquid and gaseous phases of the LPG fuel. Preferably adapted for use with replaceable fuel canisters, the ECM-managed system has a hot-soak vapor purge system as well as various sensors and valves to prevent excessive boil-off and to otherwise manage the heat and the related liquid-vapor balance of the fuel supply. Although various control strategies are contemplated in different respects, the system preferably uses an intermediate pressure vessel in which the amount of gravity-fed liquid LPG is monitored using a float sensor or the equivalent, and the system is programmed to intervene through valve controls to vent excessively hot LPG vapors from the pressure vessel directly to the engine's intake manifold as a way of managing the heat and liquid-vapor balance in the pressure vessel, accommodating the vented flow by blending the vented fuel vapors with fuel from liquid rail injectors to still produce the desired overall mass flow rate of the fuel to produce the appropriate power levels from the engine.