Jet pump including flexible venturi

#The present invention relates to a jet pump, and more particularly, to a jet pump for use with an in-tank fuel pump system for an automobile.

#In recent years, an increasing number of automobiles have included fuel systems wherein the fuel pump for the system is incorporated within the fuel tank of the automobile. In such systems, the fuel pump is typically located within a canister in the fuel tank and the canister is overfilled with fuel supplied from a fuel return line for returning an oversupply of fuel from the automobile's engine. As the fuel returns from the engine through the return line, it is typically caused to pass through a venturi orifice and into an inlet passage leading into the canister. The inlet passage is submerged in fuel within the fuel tank and the fuel exiting the venturi orifice creates a pressure drop in the area of the inlet passage such that additional fuel from the fuel tank is conveyed into the canister along with fuel jetted from the venturi orifice into the inlet passage. The amount of fuel returning through the fuel return line generally varies from between 20 to 180 liters/hr. Currently, venturis are of a low performance design wherein the average aspirated fuel is sufficient to keep the fuel canister filled under most operating conditions. However, there is a trend toward providing higher performance venturis which maintain sufficient canister filling at fuel return line flow rates as low as 20 liters/hr.

#The venturis currently in use are generally formed as fixed nozzles wherein the orifice size is optimized for the anticipated use. In order for the venturi to draw sufficient fuel into the canister from the fuel tank along with the fuel stream from the venturi, it is necessary to select a small enough orifice size for the venturi to provide the required pressure drop across the orifice to draw fuel from the fuel tank into the inlet passage of the canister. Thus, in order to increase the flow rate of fuel into the canister at low fuel return line pressures, it is necessary to decrease the orifice size of the venturi whereby a larger pressure drop across the venturi orifice is obtained and a larger flow of fuel from the fuel tank is drawn into the canister inlet passage.

#FIG. 1 illustrates the jet pump of the present invention in cross section in combination with a fuel system;

#FIG. 2 is an enlarged cross sectional view of the jet pump of the present invention;

#FIG. 3 is a diagrammatic view depicting fluid flows around the venturi of the jet pump;

#Referring to FIG. 1, the jet pump 10 of the present invention is shown in combination with an automobile fuel system including a fuel tank 12 and a fuel pump 14 contained within a canister 16. The fuel pump 14 supplies fuel from the canister 16 to an engine (not shown) through a supply line 18. Excess fuel from the engine is returned to the fuel tank 12 through a return supply line 20. The supply line 20 is connected to the jet pump 10 for feeding the fuel from the supply line 20 into the canister 16 along with additional fuel from the fuel tank 12 surrounding the jet pump 10. The jet pump 10 will generally provide an oversupply of fuel to the canister 16 such that the fluid level 22 of fuel within the canister 16 may exceed the fluid level 24 of the fuel exterior of the canister 16.

#Referring to FIG. 2, an enlarged view of the jet pump 10 is shown. The jet pump 10 includes a venturi mount 26 supported on a housing 28. The housing 28 includes a forward end 30 defining an inlet passage 32. The inlet passage 32 is adapted to be placed in fluid communication with the interior of the canister 16, as illustrated in FIG. 1.

#The venturi mount 26 includes a fluid supply end 34 defining a central fluid supply passage 36. The venturi mount 26 further includes a valve seat 38 mounted to the end 34 and in engagement with the housing 28. The valve seat 38 includes a central opening 40 and a plurality of radially located vent apertures 42 surrounding the opening 40.