Liquid propane fuel delivery system

A method of storing liquid propane fuel on a vehicle and supplying liquid propane fuel to an automotive internal combustion engine of the vehicle equipped with fuel injectors and an on-board computerized electronic engine control unit (EECU), the engine being operable for developing driving power to the vehicle in response to vehicle-operator input control commands, said method comprising the steps of:

• (1) providing a fuel storage tank constructed to withstand interior pressures sufficient to maintain propane fuel in a liquid state in a tank interior chamber at least up to normal elevated ambient vehicle operational temperatures,
• (2) communicating liquid propane fuel via conduit means between the tank interior and the engine fuel injectors during engine operation by delivering fuel from the tank interior chamber to the injectors and returning excess fuel from the injectors to the tank interior chamber via the conduit means in bypass relation to injector output to the engine,
• (3) causing fuel pressure at the input to the fuel injectors to exceed tank interior chamber pressure by a given pressure differential amount in the conduit means,
• (4) just prior to engine start-up causing delivery of propane from the tank interior chamber in a liquid state past the fuel injectors and back to the tank interior chamber via the conduit means with a relatively high flow rate by proportionately reducing the pressure differential amount in the conduit means just prior to engine fuel delivery output operation of said fuel injectors to thereby purge propane vapor from the conduit means at the input to the injectors, and
• (5) then starting the engine while continuing to pump propane to the fuel injectors via the conduit means in a liquid state concurrently with engine fuel delivery operation thereof by again causing fuel delivery pressure at the input to the injectors to exceed tank interior chamber pressure by at least said given pressure differential amount in the conduit means.

A liquid propane fuel storage and fuel delivery system for supplying liquid propane fuel to a vehicle-installed automotive internal combustion engine equipped with fuel injectors and an on-board computerized electronic engine control unit (EECU), the engine being operable for developing driving power to the vehicle in response to vehicle-operator input control commands, said system comprising:

• (1) a fuel storage tank constructed to withstand interior pressures sufficient to maintain propane fuel in a liquid state in a tank interior chamber even at elevated ambient temperatures sufficient to generate a propane vapor pressure in the tank interior chamber of at least about 312 psig, said tank containing a tank level sensor operable to provide an electrical signal indicating the level of liquid propane in the tank interior chamber,
• (2) an engine fuel delivery conduit operably coupled for communicating propane fuel between the tank interior chamber and the engine fuel injectors and including a supply line for delivering propane fuel from the tank interior chamber to the injectors and a return line for returning excess fuel from the injectors to the tank interior chamber in bypass relation to injector output to the engine,
• (3) a pair of first and second electric fuel pumps having a common pump inlet conduit disposed in the lowest elevation of the tank interior chamber and having a common pump outlet operably coupled in series with said fuel delivery conduit for pumping liquid propane from the tank interior chamber to said supply line at a pressure above tank interior chamber pressure,
• (4) a fuel handling component and passageway module removably mounted on a top wall of said tank and containing the following components and associated passageways intercoupled between said tank interior chamber, said common pump outlet and said fuel delivery conduit,
• (a) a solenoid-operated fuel supply valve for opening and closing communication between said common pump outlet and said supply line,
• (b) a fuel return check valve for opening communication from said return line to said tank interior chamber in response to return line fuel pressure exceeding tank interior chamber pressure by a given pressure differential amount, and preventing reverse flow from the tank interior chamber into said return line,
• (c) a bypass valve for bypassing fuel from said return line past said fuel return check valve into the tank interior chamber in response to a flow direction pressure differential thereacross much less than said given pressure differential amount and also being operable as a reverse flow check valve for preventing reverse flow from the tank interior chamber to said return line,
• (d) a tank fill passageway for admitting liquid propane from a tank-external source of supply to the tank interior chamber, and an associated solenoid-operated two-stage tank fuel fill valve having a primary stage solenoid operated valve member for automatically opening and closing said fill passageway in response to a tank level control signal, and a second stage valve member operable upstream of said primary valve member as a hydrostatic back check valve for closing communication between the tank interior chamber and said fill passageway when said primary stage valve member is operated in a non-tank filling phase of system operation, and
• (5) system electronic control means (SECU) operably electrically coupled in controlling relation to said pumps, said fuel supply valve, said bypass valve, said fill valve and operably slave coupled to control said EECU and for automatically causing:
• (a) operation of one and/or two of said pumps as required to deliver liquid propane from the tank interior chamber to the common pump outlet,
• (b) engine fuel delivery operation of said fuel supply valve to deliver liquid propane pumped from said common pump outlet to said fuel delivery conduit supply and return lines,
• (c) tank fill opening and closing operation of the fuel fill valve,
• (d) pre-engine-start-up opening and closing of the return check bypass valve via purge operation opening and closing of the primary stage valve member of said fill valve, and
• (e) closing operation of said fill valve to stop filling of said tank at approximately the 80% liquid full level as determined from the tank level control signal from said tank level sensor.

A method of storing pressurized fluid fuel and supplying such fuel to apparatus adapted to consume such fuel by combustion thereof in use, said method comprising the steps of:

• (1) providing a fuel storage tank constructed to withstand interior pressures sufficient to maintain such fuel liquid in a tank interior chamber at least up to normal elevated ambient operational temperatures of such apparatus,
• (2) communicating such fuel via conduit means between the tank interior and the fuel consuming apparatus during operation thereof by delivering fuel from the tank interior chamber to the apparatus and returning excess fuel from the apparatus input to the tank interior chamber via the conduit means in bypass relation to the apparatus,
• (3) causing fuel pressure at the input to the fuel consuming apparatus to exceed tank interior chamber pressure by a given pressure differential amount in the conduit means,
• (4) just prior to apparatus start-up causing delivery of fuel from the tank interior chamber in a liquid state past the apparatus fuel input and back to the tank interior chamber via the conduit means with a relatively high flow rate by proportionately reducing the pressure differential amount in the conduit means just prior to apparatus start-up to thereby purge the conduit means at the input to the apparatus, and
• (5) then starting fuel combustion in the apparatus while continuing to pump fuel via the conduit means concurrently with apparatus fuel consuming operation by again causing fuel delivery pressure at the input to apparatus to exceed tank interior chamber pressure by at least said given pressure differential amount in the conduit means.