LOW-PRESSURE PUMP FOR FUEL SYSTEM AND VENT CHECK VALVE THEREFOR

Abstract

A fuel system for an internal combustion engine includes a low-pressure pump with a vent check valve. The vent check valve extends into the outlet flow path at a junction of the outlet flow path and a vent flow path connecting an inlet flow path of the low-pressure pump to the outlet flow path.

Claims

[1] A fuel system for an internal combustion engine, the fuel system comprising: a low-pressure pump having an inlet flow path for receiving fuel from a fuel source, the low-pressure pump having an outlet flow path for discharging pressurized fuel, the low-pressure pump including: a vent flow path extending from the inlet flow path to the outlet flow path, the vent flow path including a vent path seat; and a pumping flow path connected to the inlet flow path downstream of the venting flow path, the pumping flow path further connected to the outlet flow path upstream of the venting flow path; and a vent check valve connecting the vent flow path to the outlet flow path, the vent check valve including a valve element and a valve seat in the outlet flow path, the valve element engaging the vent path seat to close the vent flow path and sliding into engagement with the valve seat in the outlet flow path to open the vent flow path. [2] The fuel system of claim 1, further comprising: a high-pressure pump downstream of the low-pressure pump; and a fuel tank upstream of the low-pressure pump. [3] The fuel system of claim 2, further comprising an electric lift pump in the fuel tank, the electric lift pump operable to provide pressurized fuel to the low pressure pump to displace the valve element from the vent seat to the valve seat during venting of the fuel system. [4] The fuel system of claim 1, wherein the low pressure pump includes a gear assembly in the pumping flow path, the gear assembly being driven by a camshaft to pump fluid from the inlet flow path to the outlet flow path, and the camshaft being driven by an output shaft of the internal combustion engine. [5] The fuel system of claim 4, wherein the gear assembly includes a first gear and a second gear meshing with the first gear. [6] The fuel system of claim 1, wherein the vent check valve includes: a base engaging the low pressure pump; a shaft extending from the base into the outlet flow path, the valve seat being disposed at one end of the shaft; and a spring around the shaft, the spring engaging the valve element to bias the valve element toward the vent path seat. [7] The fuel system of claim 6, wherein the outlet flow path includes a cross-sectional width and the wave extends over at least one-third of the cross-sectional width of the outlet flow path. [8] A fuel system according to claim 7, wherein the wave extends over at least half the cross-sectional width of the outlet flow path. [9] A fuel system according to claim 6, wherein the valve element is a ball valve and the valve seat is a concave recess in the end of the shaft. [10] The fuel system of claim 6, wherein the spring extends from the base through the outlet flow path to bias the valve element to the vent path seat. [11] The fuel system of claim 10, wherein the shaft is disposed in the outlet flow path and supports the spring in the outlet flow path. [12] The fuel system of claim 6, wherein the shaft includes at least one bore extending transversely through the shaft to allow fuel flow in the outlet flow path through the shaft. [13] The fuel system of claim 1, wherein the low pressure pump includes a pressure relief valve in fluid communication with the outlet flow path, the pressure relief valve configured to open the outlet flow path to fluidly connect the outlet flow path to the inlet flow path in response to a fluid pressure in the outlet flow path exceeding a pressure threshold. [14] A vent check valve for a low-pressure pump of a fuel system, the vent check valve comprising: a base engageable with the low pressure pump; an elongated shaft extending from the base, the elongated shaft including a valve seat at an end of the shaft opposite the base; a spring positioned around the shaft; and a valve element supported by the spring, the spring biasing the valve element away from the valve seat to a first position, the spring being compressed as the valve element is moved toward engagement with the valve seat, the shaft supporting a majority of a length of the spring in the first position. [15] A vent check valve according to claim 14, wherein: the valve seat is a concave recess in the end of the shaft; and the valve element is a ball valve which is received in the concave recess when the valve element engages the valve seat. [16] A vent check valve according to claim 14, wherein: the shaft has a length extending from the base to the end of the shaft; and the shaft includes at least one bore extending transversely to the length through the shaft. [17] A vent check valve according to claim 16, wherein the shaft includes a plurality of bores extending therethrough transversely to the length of the shaft. [18] The vent check valve of claim 14, further comprising a head extending from the base opposite the shaft, and wherein the base projects radially outwardly from the shaft and the head projects radially outwardly from the base. [19] Low-pressure pump for a fuel system of an internal combustion engine, the low-pressure pump comprising: a housing that contains the following: an inlet flow path for receiving fuel from a fuel source; an outlet flow path for discharging pressurized fuel; a vent flow path extending from the inlet flow path to the outlet flow path, the vent flow path including a vent path seat; and a pumping flow path connected to the inlet flow path downstream of the venting flow path, the pumping flow path further connected to the outlet flow path upstream of the venting flow path; a vent check valve engaged with the housing, the vent check valve including: a shaft extending into the exhaust flow path to a valve seat in the exhaust flow path; a spring around the shaft; and a valve element supported by the spring, the spring biasing the valve element into engagement with the vent flow path seat to close the vent flow path, and the valve element being displaced to compress the spring and engage the valve seat in the outlet flow path to open the vent flow path. [20] A low pressure pump according to claim 19, wherein the valve element is partially located in the outlet flow path and in the vent flow path while engaging the valve seat.

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