Pumping element for a fluid pump and method

A fuel pump for an internal combustion engine, the fuel pump having a housing forming an inlet port, an outlet port, and a return port, the fuel pump operating to pump fuel from the inlet port to the outlet port, the fuel pump comprising:

• a cooling fuel inlet port formed in the housing,
• a cooling fuel supply passage formed in the housing in fluid communication with the cooling fuel inlet port;
• a barrel disposed within the housing, the barrel defining a bore extending through the barrel and having a centerline;
• a plunger at least partially disposed within the bore, the plunger arranged for reciprocal motion within the bore;
• a pressurization cavity at least partially defined between an end of the plunger and an end portion of the bore, the pressurization cavity adapted for pressurizing an amount of fuel supplied through the inlet port and provided to the outlet port;
• an annular clearance defined between an outer surface of the plunger and an inner surface of the bore, the annular clearance in fluid communication with the pressurization cavity;
• an annular collector defined around the inner surface of the bore, the annular collector surrounding a portion of the plunger, the annular collector being in fluid communication with the annular clearance;
• an annular reservoir defined peripherally around the barrel and between the barrel and the housing, the annular reservoir being in fluid communication with the return port;
• at least one weep opening formed in the barrel, the at least one weep opening fluidly connecting the annular collector with the annular reservoir;
• wherein the annular reservoir is in fluid communication with the cooling fuel supply passage.

A method of operating a fluid pump at a high pressure, the fluid pump including a barrel having a bore extending therethrough, the bore reciprocally accepting a plunger, the reciprocating motion of the plunger including a pressurization stroke and a refill stroke, the plunger moving toward the barrel during the pressurization stroke, the method comprising:

• admitting fluid into a pressurization chamber during the refill stroke, the pressurization chamber at least partially defined between the plunger and the bore;
• pressurizing the fluid during the pressurization stroke;
• flowing fluid out of the pressurization chamber and along a clearance between the plunger and the bore;
• collecting the fluid flowing along the clearance into a collection chamber, the collection chamber defined in the barrel around a portion of the plunger adjacent to the bore;
• routing a flow of fluid out of the collection chamber through at least one weep opening;
• collecting the flow of fluid from the at least one weep opening into an annular reservoir, the annular reservoir defined peripherally around a portion of the barrel;
• and
• supplying a flow of cooling fluid into the annular reservoir;
• mixing the flow of cooling fluid with the flow of fluid from the collection chamber to form a mixture in the annular reservoir;
• and
• conducting heat away from the plunger by removing the mixture from the annular reservoir.