LPG Fuel System

Abstract

Disclosed is a liquefied petroleum fuel system for internal combustion engines that improves fuel economy by mixing vaporized liquid petroleum gas (LPG) and ambient air at substantially equal random kinetic energies. The system maintains a certain vapor pressure in the LPG tank and delivers the LPG in a gaseous phase to an LPG burning device at a set pressure and temperature. The cycle repeats as necessary to maintain the desired pressure in the tank.

I claim: 
     
         1 . A liquefied petroleum fuel system that improves fuel economy by mixing vaporized liquid petroleum gas and ambient air at substantially equal random kinetic energies, wherein vaporized liquid petroleum gas is delivered to a liquid petroleum burning device at a set pressure and temperature. 
     
     
         2 . The liquefied petroleum fuel system of  claim 1  wherein an electric pump pumps liquid petroleum gas from a fuel tank through a heat exchanger, wherein the heat exchanger vaporizes the liquid petroleum gas. 
     
     
         3 . The liquefied petroleum fuel system of  claim 2  wherein vaporized liquid petroleum gas is returned to the fuel tank. 
     
     
         4 . The liquefied petroleum fuel system of  claim 3  wherein vaporized liquid petroleum gas is pushed from the fuel tank through a second filter and a pressure regulator into an engine's fuel rail and injected into the air stream to be mixed with the ambient air. 
     
     
         5 . A liquefied petroleum fuel system comprising:
 a pressure sensor that monitors the vapor pressure in a fuel tank and activates an electric pump that circulates liquid propane through a heat exchanger; and   a pressure switch that eliminates power to the electric pump and solenoid valves to stop the circulation of liquid propane.   
     
     
         6 . The liquefied petroleum fuel system of  claim 5  wherein:
 A first vapor outlet connects a solenoid valve, a manual valve, a pressure switch, a filter, a pressure regulator, and a pressure gauge to an internal combustion engine via a flow communication means. 
 
     
     
         7 . The liquefied petroleum fuel system of  claim 6  wherein a second vapor outlet of the said fuel tank is connected, via said flow communication means, to one solenoid switch, one manual valve, and a hot outlet of the said heat exchanger. 
     
     
         8 . The liquefied petroleum fuel system of  claim 7  wherein the liquid outlet of the said fuel tank is connected, via said flow communication means, to a solenoid valve, a manual valve, a filters, said fuel pump, another of said solenoid valves, then to the cold inlet of the said heat exchanger. 
     
     
         9 . The liquefied petroleum fuel system of  claim 8  wherein engine coolant is metered. 
     
     
         10 . The liquefied petroleum fuel system of  claim 9  wherein said pressure gauge checks the pressure in the fuel rail. 
     
     
         11 . The liquefied petroleum fuel system of  claim 10  wherein said pressure gauge determines the condition of a liquefied petroleum fuel filter. 
     
     
         12 . The liquefied petroleum fuel system of  claim 11  further defined by a built in safety mechanism wherein if the solenoid valve fails to open the engine will not start. 
     
     
         13 . The liquefied petroleum fuel system of  claim 12  wherein liquid petroleum gas passes through a filter and is routed into the pressure regulator, wherein the pressure regulator regulates the vapor output to a set pressure. 
     
     
         14 . The liquefied petroleum fuel system of  claim 13  wherein the solenoid valves isolate the tank contents from the fuel system and engine rail when the engine is shut off. 
     
     
         15 . The liquefied petroleum fuel system of  claim 14  wherein multiple solenoid valves may be powered on and off at the same time via the pressure switch. 
     
     
         16 . The liquefied petroleum fuel system of  claim 15  wherein the solenoid valve shuts off the liquid line when the pressure switch senses that the tank pressure has reached the threshold pressure. 
     
     
         17 . A method of mixing equalized kinetic energies of vaporized liquid petroleum gas and air by:
 obtaining a liquid petroleum gas fuel system comprising of a fuel tank, a heat exchanger, a pressure sensor, at least one pressure switch, an electric pump;   pumping liquid petroleum gas from a fuel tank through a heat exchanger, wherein heat from engine coolant is used to vaporize the liquid petroleum gas; returning the vaporized liquid petroleum gas to the fuel tank so that liquid petroleum gas and vaporized liquid petroleum gas occupy the fuel tank; and,   mixing vaporized liquid petroleum gas with air from the atmosphere.