Method of forming a diaphragm for a liquid pump

1 . A method of forming a diaphragm for a liquid pump, comprising:

securing a substantially planar piece of material, about a periphery thereof, between a set of opposed clamps;

plastically deforming the piece of material inboard of the clamped periphery by applying a fluid under pressure against the material to cause the piece of material to stretch beyond an elastic limit and retain an offset non-planar shape after removal of the fluid pressure; and

assembling the plastically deformed diaphragm into a pump housing of the liquid pump such that the diaphragm separates a liquid fuel chamber from a pressure chamber and is operable, in response to pressure differentials, to vary the volume of the liquid fuel chamber to pump liquid through an inlet valve and an outlet valve.

2 . The method of claim 1 , wherein the step of plastically deforming the piece of material is done by forming the piece of material into a non-planar shape that includes a rim and an offset portion located inwardly of the rim.

3 . The method of claim 2 , wherein the offset portion is formed into a frustro-conical shape.

4 . The method of claim 2 , wherein the offset portion frustro-conical shape includes a center region that is at a furthest offset distance from the rim, and the offset portion includes a tapered sidewall extending from the center region.

5 . The method of claim 4 , wherein the tapered sidewall has a maximum diameter adjacent to the rim and a minimum diameter adjacent to the center region.

6 . The method of claim 4 , wherein the center region is formed by the fluid under pressure into a flat shape.

7 . The method of claim 1 , wherein the material is formed from a polyamide, polyester, fluoropolymer, polyacetal, polyethylene, or an alloy or copolymer thereof.

8 . The method of claim 1 , wherein the material is formed from a semi-crystalline plastic, nylon 6,6, polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), polyethylene terephthalate (PET), polyoxymethylene (POM), low-density polyethylene (LDPE), or ethylene vinyl alcohol (EVOH).

9 . The method of claim 1 , wherein the material is formed from stainless steel.

10 . The method of claim 1 , wherein, prior to being plastically deformed, the material has a thickness between 0.2 mm to 0.8 mm.

11 . The method of claim 1 , wherein the material is formed from perfluoroalkoxy (PFA), polyfluoroethylenepropylene (FEP), or polytetrafluoroethylene (PTFE).

12 . The method of claim 1 , wherein plastically deforming comprises stretching the piece of material until the material yields plastically while remaining continuous and free of perforations.

13 . The method of claim 1 , further comprising forming voids in a rim portion of the plastically deformed diaphragm, the voids receiving gasket material in assembly to interlock the diaphragm with the pump housing.

14 . The method of claim 1 , wherein assembling the diaphragm into the pump housing further comprises trapping the diaphragm periphery between the pump housing and a cover with a gasket that engages the diaphragm through the voids.

15 . The method of claim 1 , wherein plastically deforming forms the diaphragm with a bead at its periphery adapted to be seated between opposed annular surfaces of the pump housing to seal the liquid fuel chamber.

16 . A method of forming a diaphragm for a liquid pump, comprising:

securing a substantially planar piece of material, about a periphery thereof, through a plurality of apertures between a set of opposed clamps;

plastically deforming the piece of material inboard of the clamped periphery by applying a fluid under pressure against the material to cause the piece of material to stretch beyond an elastic limit and retain an offset non-planar shape;

assembling the plastically deformed diaphragm into a pump housing of the liquid pump to separate a liquid fuel chamber from a pressure chamber; and

in response to pressure differentials, varying the volume of the liquid fuel chamber with the plastically deformed diaphragm to pump liquid through an inlet valve and an outlet valve.

17 . The method of claim 16 , wherein the material is formed from perfluoroalkoxy (PFA), polyfluoroethylenepropylene (FEP), or polytetrafluoroethylene (PTFE).

18 . The method of claim 16 , further comprising forming the plastically deformed diaphragm as a multi-layer structure having at least one barrier layer to inhibit liquid fuel vapor permeation.

19 . The method of claim 16 , wherein the barrier layer is encapsulated between two elastomeric outer layers during forming.

20 . The method of claim 16 , further comprising positioning the plastically deformed diaphragm adjacent a vent opening and a vapor filter so that gases passing through the vent opening flow through the vapor filter to reduce hydrocarbon emissions.

21 . A method of forming a diaphragm for a liquid pump, comprising:

providing a substantially planar piece of material with a periphery and a radially inward portion, inboard of the periphery;

clamping the material by trapping the periphery between opposed clamps, exposing the radially inward portion;

plastically deforming the central portion by pressing the radially inward portion with a central forming member until the substantially planar piece of material deforms beyond an elastic limit to retain an offset non-planar shape including a frustoconical portion with a generally flat center region, while maintaining the diaphragm continuous and without perforations; and

assembling the plastically deformed diaphragm into a pump housing of the liquid pump to separate a liquid fuel chamber from a pressure chamber.

22 . The method of claim 21 , wherein plastically deforming the radially inward portion forms a frustro-conical shape defining a flat central portion and a tapered sidewall extending between the flat central portion and the periphery.

23 . The method of claim 21 , wherein the material is formed from perfluoroalkoxy (PFA), polyfluoroethylenepropylene (FEP), or polytetrafluoroethylene (PTFE).