Low pressure fuel supply system for a fuel injection pump

A low pressure fuel supply system for supplying fuel which tends partially to solidify at low temperatures and whose viscosity increases with decreasing temperature, comprising:

• a fuel tank;
• a fuel injection pump having an inlet, a high pressure outlet and a fuel return outlet;
• a fuel filter;
• fuel pipe means including pipes defining a fuel supply line extending from said tank, via said filter, to said injection pump inlet and a fuel recirculation circuit for recirculating fuel warmed by said injection pump along a path extending from said injection pump return outlet, through said filter to said injection pump inlet;
• and
• a permanent bleed pipe extending to said fuel tank from a portion of said recirculating circuit between said injection pump return outlet and said filter, said permanent bleed pipe having flow-resistance-determining dimensions such that said pipe presents increasing resistance to the flow of fuel therein with decreasing fuel temperature so that said permanent bleed pipe carries little flow at low temperature of the fuel therein, most of the warmed fuel from said injection pump return outlet being directed into said filter, and so that under normal operating conditions when the fuel temperature is higher, said permanent bleed pipe returns more of said warmed fuel from said injection pump return outlet to said fuel tank, thus preventing overheating of the fuel and of said injection pump, said permanent bleed pipe being substantially smaller in cross-sectional area than any of the pipes of said fuel pipe means.

A low pressure fuel supply system for supplying fuel which tends partially to solidify at low temperatures and whose viscosity increases with decreasing temperature, comprising:

• a fuel tank;
• a fuel injection pump having an inlet, a high pressure outlet and a fuel return outlet;
• a fuel filter;
• a fuel supply line extending from said tank, via said filter, to said injection pump inlet;
• a fuel recirculation circuit for recirculating fuel warmed by said injection pump along a path extending from said injection pump return outlet, through said filter to said injection pump inlet;
• and
• a permanent bleed pipe extending to said fuel tank from a portion of said recirculating circuit between said injection pump return outlet and said filter, said permanent bleed pipe having flow-resistance-determining dimensions such that said pipe presents increasing resistance to the flow of fuel therein with decreasing fuel temperature so that said permanent bleed pipe carries little flow at low temperatures of the fuel therein, most of the warmed fuel from said injection pump return outlet being directed into said filter, and so that under normal operating conditions when the fuel temperature is higher, said permanent bleed pipe returns more of said warmed fuel from said injection pump return outlet to said fuel tank, thus preventing overheating of the fuel and of said injection pump, said permanent bleed pipe having a nonuniform cross-section, and including a first bleed pipe portion connected in series with a flow-resistance-determining bleed pipe portion of smaller cross-sectional area than said first bleed pipe portion.

A low pressure fuel supply system for supplying fuel which tends partially to solidify at low temperatures and whose viscosity increases with decreasing temperature, comprising:

• a fuel tank;
• a fuel injection pump having an inlet, a high pressure outlet and a fuel return outlet;
• a fuel filter;
• a fuel supply line extending from said tank, via said filter, to said injection pump inlet;
• a fuel recirculation circuit for recirculating fuel warmed by said injection pump along a path extending from said injection pump return outlet, through said filter to said injection pump inlet;
• a permanent bleed pipe extending to said fuel tank from a portion of said recirculating circuit between said injection pump return outlet and said filter, said permanent bleed pipe having flow-resistance-determining dimensions such that said pipe presents increasing resistance to the flow of fuel therein with decreasing fuel temperature so that said permanent bleed pipe carries little flow at low temperatures of the fuel therein, most of the warmed fuel from said injection pump return outlet being directed into said filter, and so that under normal operating conditions when the fuel temperature is higher, said permanent bleed pipe returns more of said warmed fuel from said injection pump return outlet to said fuel tank, thus preventing overheating of the fuel and of said injection pump;
• said fuel tank including a first fuel tank portion partially separated from a second fuel tank portion by a baffle;
• and
• said recirculating circuit including said first fuel tank portion, a fuel return line portion of said recirculating circuit being positioned to return fuel to said first fuel tank portion, said fuel supply line being positioned to draw fuel from said first fuel tank portion and said permanent bleed pipe being positioned to return fuel to said second fuel tank portion.

A low pressure fuel supply system for supplying fuel which tends partially to solidify at low temperatures and whose viscosity increases with decreasing temperature, comprising:

• a fuel tank;
• a fuel injection pump having an inlet, a high pressure outlet and a fuel return outlet;
• a fuel filter;
• a fuel supply line extending from said tank, via said filter, to said injection pump inlet;
• a fuel recirculation circuit for recirculating fuel warmed by said injection pump along a path extending from said injection pump return outlet, through said filter to said injection pump inlet;
• and
• a permanent bleed pipe extending to said fuel tank from a portion of said recirculating circuit between said injection pump return outlet and said filter, said permanent bleed pipe having flow-resistance-determining dimensions such that said pipe presents increasing resistance to the flow of fuel therein with decreasing fuel temperature so that said permanent bleed pipe carries little flow at low temperatures of the fuel therein, most of the warmed fuel from said injection pump return outlet being directed into said filter, and so that under normal operating conditions when the fuel temperature is higher, said permanent bleed pipe returns more of said warmed fuel from said injection pump return outlet to said fuel tank, thus preventing overheating of the fuel and of said injection pump, and including at least one further permanent bleed pipe connected in parallel with said first-mentioned permanent bleed pipe.