Arrangement and Method for an Internal Combustion Engine with Direct Dual Fuel Injection

Abstract

An arrangement and a method for a combustion engine with direct injection and in particular for switching between two types of fuel. A high-pressure pump is connected to a combustion engine and the high-pressure rail for the direct injection of a fuel. At least two fuel storages containing petrol and liquefied gas are present. The arrangement allows for switching from one fuel to another. Switching occurs by purging a fuel from the high-pressure pump and the fuel supply line connected thereto by temporarily collecting the fuel in a purge unit. The purge unit is arranged for purging the high-pressure pump, thus forcing out the prevailing fuel and replacing it with the new fuel.

1 - 24 . (canceled) 
     
     
         25 . Arrangement for a combustion engine with direct injection, comprising at least one high pressure pump connectable to the internal combustion engine for the direct injection of fuel, wherein said arrangement comprises at least two fuel storages for a first fuel and a second fuel, for example liquefied vapour and petrol respectively, as well as two lines running from the storages to an inlet of the high-pressure pump for supplying the fuels to said pump, said lines being provided with non-return valves, wherein a control valve is mounted across a non-return valve in the petrol fuel line. 
     
     
         26 . Arrangement for the supply of fuel to a combustion engine with direct injection, comprising at least one high pressure pump connectable with the internal combustion engine for the direct injection of fuel, wherein said arrangement comprises at least two fuel storages for a first LPG fuel storage and a second liquid fuel storage, as well as two lines running from the fuel storages to an inlet of the high-pressure pump for supplying the fuels to said pump, said lines being provided with non-return valves, wherein said arrangement is provided with a purge unit for purging the fuel line connected to said high-pressure pump. 
     
     
         27 . The arrangement according to  claim 26 , wherein said purge unit is arranged for equalizing the pressure in the fuel line. 
     
     
         28 . The arrangement according to  claim 26 , wherein said arrangement comprises a control unit, connected to said purge unit, and which is arranged so as to activate the purge unit when switching from LPG to liquid fuel. 
     
     
         29 . The arrangement according to  claim 26 , wherein said purge unit is incorporated in the line of the liquid fuel storage to the high-pressure pump. 
     
     
         30 . The arrangement according to  claim 26 , wherein the purge unit comprises an intensifier for increasing the fuel pressure in said fuel line. 
     
     
         31 . The arrangement according to  claim 30 , wherein the intensifier is a hydraulic pressure intensifier. 
     
     
         32 . The arrangement according to  claim 31 , wherein the pressure intensifier comprises two pistons with different diameters and a cylinder with a constriction. 
     
     
         33 . The arrangement according to  claim 30 , wherein the pressure intensifier comprises a discharge with a return line to the fuel storage. 
     
     
         34 . The arrangement according to  claim 30 , wherein the fuel line comprises a non-return valve in the form of a bypass of the intensifier. 
     
     
         35 . The arrangement according to  claim 26 , wherein the fuel lines have a junction upstream of the high-pressure pump, wherein at least one fuel line comprises a return line to the fuel storage upstream of said junction. 
     
     
         36 . The arrangement according to  claim 33 , wherein a shutter is incorporated in the line between the connection of the return line and the line junction. 
     
     
         37 . The arrangement according to  claim 26 , wherein the high-pressure pump also comprises a return fuel line, wherein the purge unit is connected to the return line. 
     
     
         38 . The arrangement according to  claim 37 , wherein the high-pressure pump return line is connected to the liquefied fuel storage means. 
     
     
         39 . The arrangement according to  claim 26 , wherein an inlet of the purge unit is connected to the liquid fuel storage. 
     
     
         40 . The arrangement according to  claim 26 , wherein the purge unit comprises a pressure accumulator. 
     
     
         41 . The arrangement according to  claim 40 , wherein a supply line of the pressure accumulator is connected to a high-pressure rail arranged downstream from the high-pressure pump. 
     
     
         42 . Method for the alternate injection of two types of fuel, comprising the provision of a first LPG fuel storage and a second liquid fuel storage, switching between the fuels by alternately supplying the fuels to a high-pressure pump, increasing the pressure of the supplied fuel, and the subsequent injection of the fuel into a combustion engine, wherein switching from the LPG fuel to the liquid fuel comprises purging the fuel supplied to the high-pressure pump, and wherein said purging action comprises equalizing the pressure of the supplied fuels. 
     
     
         43 . The method according to  claim 42 , wherein said purging action comprises at least the temporary accumulation of the other fuel and the subsequent supply and injection of the accumulated fuel. 
     
     
         44 . The method according to  claim 42 , wherein said purging action comprises the supply of the liquid fuel under increased pressure, wherein the increased pressure is obtained by the use of a hydraulic stroke of a displacement means. 
     
     
         45 . The method according to  claim 42 , wherein switching from the one fuel to the other fuel comprises activating the other fuel pump, using said fuel pump to generate a predefined pressure level, and, after the predefined pressure level is reached, the displacement of the one fuel downstream. 
     
     
         46 . The method according to  claim 45 , wherein switching off the one fuel pump occurs after a predefined pressure is reached. 
     
     
         47 . The method according to  claim 42 , wherein switching from the second fuel to the first fuel comprises the reduction of the supply of fuel to the engine of 10-40% vol. 
     
     
         48 . The method according to  claim 42 , wherein the purging operation comprises the evacuation of the supplied fuel via the high-pressure pump.