Inlet pressure attenuator for single plunger fuel pump

Abstract

An attenuator diaphragm assembly for a fuel injection pump, comprising a diaphragm formed of two half-shells, having mated flat rims that are welded together along their peripheral edges and a compression joint formed at inward, unwelded portions of the rims, and a carrier that captures the joined and welded rims.

1 . In a fuel pump having single plunger that reciprocates into and out of a pumping chamber situated within a pump housing; a pressurized inlet line through the housing to an inlet valve that feeds the pumping chamber; a damping chamber 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 being formed of two half-shells, having central convex bulges and mated flat rims which are supported in a diaphragm carrier within the damping chamber; wherein the improvement comprises that 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. 
     
     
         2 . The fuel pump of  claim 1 , wherein the rims are bent over at a bend line that forms said compression joint. 
     
     
         3 . The fuel pump of  claim 1 , wherein each half-shell is substantially circular and each rim circumscribes a respective convex bulge. 
     
     
         4 . The fuel pump of  claim 3 , wherein the rims are bent over at a circumferential bend line that forms said compression joint. 
     
     
         5 . The fuel pump of  claim 4 , wherein the bent over portion of the rims forms a circumferential ridge that is substantially coaxial with the axis of the diaphragm. 
     
     
         6 . The fuel pump of  claim 4 , wherein the circumferential bend line is located within the radially inward 75 percent of the radial dimension of the rim. 
     
     
         7 . The fuel pump of  claim 3 , wherein the diaphragm carrier has a radial slot including upper and lower walls that closely confront the inner radial portion of the rim but not the circumferential weld. 
     
     
         8 . The fuel pump of  claim 7 , wherein the radial slot circumferentially surrounds said weld. 
     
     
         9 . The fuel pump of  claim 8 , wherein the slot has a radially inner portion where the walls are clamped against the rim and a radially outer portion forming a space surrounding said weld. 
     
     
         10 . The fuel pump of  claim 7 , wherein the radial slot is one of a plurality of said slots circumferentially spaced apart around the rim. 
     
     
         11 . The fuel pump of  claim 10 , wherein each slot has a radially inner portion where the walls are clamped against the rim and a radially outer portion forming a space surrounding said weld. 
     
     
         12 . The fuel pump of  claim 1 , wherein each half-shell is substantially circular; each rim circumscribes a respective convex bulge; the rims are bent over at a circumferential bend line that forms said 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; and the ridge is captured between the upper and lower walls. 
     
     
         13 . The fuel pump of  claim 12 , wherein 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. 
     
     
         14 . An attenuator diaphragm assembly for a fuel injection pump, comprising: a diaphragm formed of two half-shells, having mated flat rims that are welded together along their peripheral edges and a compression joint formed at inward, unwelded portions of the rims; and a carrier that captures the joined and welded rims. 
     
     
         15 . The attenuator diaphragm of  claim 14 , wherein each half-shell is substantially circular; each rim circumscribes a respective convex bulge; the rims are bent over at a circumferential bend line that forms said 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; and the ridge is captured between the upper and lower walls. 
     
     
         16 . The attenuator diaphragm of  claim 15 , wherein 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.