A pressure damper assembly for a fuel inlet passage in a single piston high pressure fuel pump, comprising:
- an inlet fitting;
- a cover attached to the fitting and having a substantially cylindrical sidewall defining a damper assembly axis, an internal chamber within the sidewall in fluid communication with the fuel inlet passage of the pump, and a bottom sealingly attached to the pump;
- a plurality of diaphragm assemblies supported within the damping chamber, wherein
- each said diaphragm assembly includes first and second metal diaphragms having respective flat rims sealingly secured to respective first and second sides of an imperforate center plate and convex central regions spaced from the center plate, thereby defining first and second independent closed gas volumes radially inward of a surrounding diaphragm assembly rim;
- the center plate and diaphragms are circular and centered at said axis, and have the same radius defining the circumferences of the diaphragms and center plate and a circumferential edge of the diaphragm assembly;
- and
- the rim of each diaphragm is joined by weldment to the center plate at the circumferential edge of the diaphragm assembly;
- a retainer assembly supported within the cover, having first and second elements that bear in axial opposition on the circumferential edge of the diaphragm assembly;
- wherein the retainer assembly supports two distinct, axially spaced upper and lower of said diaphragm assemblies within the cover, including
- a first retainer having a radially outward oblique projection that bears on and biases an upper portion of the circumferential edge of the upper diaphragm assembly;
- a second retainer having a radially outward oblique projection that bears on and biases a bottom portion of the circumferential edge of the lower diaphragm assembly;
- a spacer having a radially outward oblique upper projection that bears on and biases a bottom portion of the circumferential edge of the upper diaphragm assembly and a radially outward oblique lower projection that bears on and biases the upper portion of the circumferential edge of the lower diaphragm assembly;
- and
- an upper portion of the cover as attached to the pump bears axially on the first retainer and the second retainer is axially immobilized by the pump housing, whereby the projections on the retainers are spring loaded against the projections of the spacer;
- whereby the bias on the circumferential edges maintains the diaphragm assemblies in place within the retainer assembly and feed fuel delivered to the pump through the inlet fitting flows through said damping chamber at a pressure that acts on the first and second diaphragms of each diaphragm assembly before entry into the inlet passage of the pump.