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Inlet pressure attenuator for single plunger fuel pump

Inlet pressure attenuator for single plunger fuel pump description/claims

This application claims priority under 35 U.S.C. 119(e) from U.S. Provisional Application No. 60/879,738 filed Jan. 10, 2007 for “Inlet Pressure Attenuator for Single Plunger Fuel Pump”, the entire disclosure of which is hereby incorporated by reference.

The present disclosure relates generally to fuel pumps, and is more particularly concerned with a new and improved single plunger fuel pump.

Practitioners in the field of fuel pump design and development for vehicles readily understand the main components of a typical single plunger pump and their function and operation. The engine drive shaft carries a lobed cam that reciprocates the pumping plunger within a pumping sleeve secured to the housing, between charging (intake) and discharging (output) phases. The pumping end of the plunger is situated in the pumping chamber, which fills with fuel at a feed pressure of up to about 4 bar during the charging phase and, preferably subject to initial spill control, pressurizes the fuel in the pumping chamber up to about 200 bar for delivery to, e.g., a common rail.

The feed fuel is fed directly to the pumping chamber through an inlet valve, which receives flow from an inlet damping chamber. The fuel passes one or more attenuator diaphragms in the damping chamber along the flow path to the pumping chamber. The diaphragms encapsulate fixed masses of gas, such as helium at two bars. The flexibility of the diaphragms can adjust the volumes of the gas in response to pressure variations in the feed line and thereby maintain a substantially constant feed pressure to the inlet valve.

A problem encountered with known welded diaphragms, is that the substantially continual accommodation of normal pressure fluctuations and the occasional attenuation of spurious pressure transients, stresses the welds and causes leakage, with resulting deterioration of performance or even failure.

It is an object of the present invention to provide an improved technique for stress relieving the junction of juxtaposed thin rims of a pressurized bellows type diaphragm attenuator that is integrated with the inlet feed train of a single plunger fuel pump.

One embodiment is directed to an attenuator diaphragm assembly for a fuel injection pump. The diaphragm assembly includes a diaphragm formed of two half-shells, having mated flat rims that are welded together along their peripheral edges. A compression joint is formed at inward, unwelded portions of the rims and a carrier or frame captures the joined and welded rims.

Another embodiment is directed to a fuel pump having a single plunger that reciprocates into and out of a pumping chamber situated within a pump housing. The pump features a pressurized inlet line through the housing to an inlet valve that feeds the pumping chamber. A damping chamber is integrated with the housing, in which fuel passes around at least one gas filled and sealed attenuator diaphragm along a flow path to the inlet valve. Each diaphragm is formed of two half-shells, having central convex bulges and mated flat rims which are supported in a diaphragm carrier within the damping chamber. The rims are welded together along their outer edges and a compression joint is formed at inward, unwelded portions of the rims to reduce stresses transmitted to the welded edges.

Preferably, each half-shell is substantially circular and each rim circumscribes a respective convex bulge. The rims are bent over at a circumferential bend line that forms the compression joint. The bent over portion of the rims forms a circumferential ridge that is substantially coaxial with the axis of the diaphragm. The diaphragm carrier has a radial slot including upper and lower walls between which the ridge is captured. Each rim has a flat portion radially inward of the bend line. The upper wall extends closely over said flat portions of the rims and the welded outer edges are supported by the lower wall.

The compression joint isolates the weld from excessive stresses associated with the expansion and contraction of the diaphragm, thereby avoiding leakage of the gas and deterioration or failure of pressure attenuating capability of the diaphragm.

In the accompanying drawing, like elements are numbered alike in the several Figures:

FIG. 1 is a perspective view of a one plunger fuel pump having a substantially cubic housing or body, with the fuel inlet connector projecting on the right, the single plunger actuation assembly projecting from the left, and the inlet control valve projecting from the top;

FIG. 2 is staggered section view of the pump of FIG. 1, through the inlet connection with associated attenuator, and the inlet control valve;

FIGS. 3A and 3B are enlarged plan and section views of the split diaphragm carrier for the two pressurized diaphragms shown in FIG. 2, with the section line indicated by A-A;

• Provisional Patent
• Utility Patent

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