US20190162177A1 - Fluid driven diaphragm pump - Google Patents

Abstract

In at least some implementations, a diaphragm for a fluid pump includes a first layer formed from a first material that inhibits or prevents vapor permeation through the diaphragm, and a second layer coupled to the first layer and formed from a second material different than the first material. The first material may include at least one of fluoropolymers, perfluoroalkoxy (PFA), polyfluoroethylenepropylene (FEP), polytetrafluoroethylene (PTFE), liquid crystal polymers, nylons, thin metal foil or film, or ethylene vinyl alcohol, and the fluoropolymer may be a fluoroelastomer. The first layer may be continuous and without perforations in an area of the diaphragm adapted to be exposed to a fluid. The first layer may include a base material and a coating that prevents vapor permeation therethrough. The second material may include at least one of NBR rubber, H-NBR, NBR coated or impregnated fiber or nylon materials, or a fluoroelastomer.

Description

REFERENCE TO RELATED APPLICATIONS
• This application claims the benefit of U.S. Provisional Application Ser. Nos. 62/369,541 filed on Aug. 1, 2016 and 62/474,136 filed on Mar. 21, 2017, the entire contents of which are incorporated herein by reference in their entireties.
TECHNICAL FIELD
• The present disclosure relates generally to a fluid driven diaphragm pump.
BACKGROUND
• Some fluid pumps utilize a diaphragm a portion of which moves in response to a pressure or force differential acting on opposed sides of the diaphragm to draw fluid into the pump and to deliver fluid from the pump under pressure. The pump diaphragm defines a fluid chamber on one side that receives fluid and a second chamber on its other side which may be open to the atmosphere or communicated with a pressure source to provide a desired pressure in the second chamber. Governmental regulations are being promulgated that limit permitted gaseous emissions (e.g. hydrocarbons) and there is a need for a fluid pump that can significantly inhibit such emissions.
SUMMARY
• In at least some implementations, a diaphragm for a fluid pump includes a first layer formed from a first material that inhibits or prevents vapor permeation through the diaphragm, and a second layer coupled to the first layer and formed from a second material different than the first material. The first material may include at least one of fluoropolymers, perfluoroalkoxy (PFA), polyfluoroethylenepropylene (FEP), polytetrafluoroethylene (PTFE), liquid crystal polymers, nylons, thin metal foil or film, or ethylene vinyl alcohol, and the fluoropolymer may be a fluoroelastomer. The first layer may be continuous and without perforations in an area of the diaphragm adapted to be exposed to a fluid. The first layer may include a base material and a coating that prevents vapor permeation therethrough. The second material may include at least one of NBR rubber, H-NBR, NBR coated or impregnated fiber or nylon materials, or a fluoroelastomer.
• In at least some implementations, a third layer may be provided and the first layer may be received between the second and third layer. The third layer may be formed from the second material. The second layer and third layer may both be overmolded on the first layer. The first layer may be fully encapsulated between the second and third layer. The second and third layers may each include a first portion adapted to be trapped between opposed bodies and the second and third layers may each also include a second portion inboard of the first portion and wherein the first layer is fully encapsulated between the second portions of the second and third layers.
• In at least some implementations, a fluid pump includes a housing having a vent opening, a diaphragm carried by the housing and defining with the housing a fluid chamber for receipt of a fluid, wherein the fuel chamber is on one side of the diaphragm and the vent opening is on the other side of the diaphragm such that liquid fuel does not flow through the vent opening, and a vent chamber communicated with the vent opening and including a vapor filter, the vapor chamber and vapor filter being arranged so that fluid flowing out of the vapor vent flows through the vapor filter. The vapor filter may include charcoal such as activated charcoal to adsorb hydrocarbons. The housing may include multiple vent openings and each vent opening may be communicated with one or more than one vapor filter.
• In at least some implementations, the vent chamber is longer than it is wide and the vapor filter is also longer than it is wide. The vapor filter may fill the volume of at least part of the vent chamber so that vapor must flow into the vapor filter and cannot flow around the vapor filter. The vent chamber may be more than 3 times as long as it is wide, and the vent chamber may have more than one change of direction and may be circuitous.
• In at least some implementations, a diaphragm for a fluid pump includes a planar rim and a center region inboard of the rim, and multiple retention features formed in the rim. The retention features may include voids formed through the rim and circumferentially spaced apart about the rim.
• In at least some implementations, a method of forming a diaphragm for a fluid pump includes clamping a substantially planar piece of material about a periphery, and plastically deforming the piece of material inboard of the clamped periphery. The material may be deformed by pressing a forming member against the material, and/or the material may be deformed by applying a fluid under pressure against the material.
• The various features and components noted above may be used in any suitable combination, as can the various method and process steps, as supported in this and the other sections of this specification including the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The following detailed description of certain embodiments and best mode will be set forth with reference to the accompanying drawings, in which:
• FIG. 1 is a side view of a fluid driven pump;
• FIG. 2 is a bottom view of the pump ofFIG. 1;
• FIG. 3 is a top view of the pump;
• FIG. 4 is a cross-sectional view of the pump taking generally along line4-4 inFIG. 3;
• FIG. 5 is a bottom view of the pump with an alternate vent cavity;
• FIG. 6 is a cross-sectional view of the pump ofFIG. 5;
• FIG. 7 is a perspective view of a sheet of material for a diaphragm;
• FIG. 8 is a perspective sectional view of part of a forming mechanism for forming a diaphragm from the material ofFIG. 7;
• FIG. 9 is a perspective sectional view of a formed diaphragm;
• FIG. 10 is a perspective view of the formed diaphragm;
• FIG. 11 is a sectional view of a pump;
• FIG. 12 is an enlarged view of the encircled portion ofFIG. 11;
• FIG. 13 is an exploded view of a portion of a pump showing a diaphragm, gasket and part of a pump housing;
• FIG. 14 is a cross-sectional view of a pump including a first diaphragm;
• FIG. 15 is a plan view of the first diaphragm;
• FIG. 16 is an enlarged cross-sectional view of a portion of the first diaphragm illustrating a multi-layer construction;
• FIG. 17 is a perspective view showing one side of a multi-layer diaphragm; and
• FIG. 18 is a perspective view showing the other side of the diaphragm ofFIG. 17.
DETAILED DESCRIPTION
• Referring in more detail to the drawings,FIGS. 1-4 illustrate a fluid drivendiaphragm pump10 that may be used, for example, to pump fuel from one location to another in a fuel system. In at least one implementation, thepump10 takes in fuel from a fuel tank and pumps the fuel to a carburetor or throttle body. In the carburetor or throttle body, the fuel is mixed with air and the fuel and air mixture is then delivered to an engine to support combustion in the engine. While thepump10 is described herein with regard to pumping fuel, it may be used to pump other fluids.
• Thepump10 includes ahousing12 and at least one pump diaphragm14 (FIG. 4) carried by the housing and having a portion movable relative to the housing to create a pumping action as is generally known in the art. Thehousing12 may include amain body16 and one or more covers with afirst cover18 and asecond cover20 shown in the illustrated example. Thediaphragm14 may be a generally thin sheet of material that is flexible, and, as shown inFIG. 4, the diaphragm may be trapped about its periphery between themain body16 andfirst cover18. So arranged, apressure chamber22 is defined between one side of thediaphragm14 and thefirst cover18, and afuel chamber24 is defined between the opposite side of thediaphragm14 and themain body16. Thediaphragm14 may be generally planar and suitably elastic to permit movement of at least part of the diaphragm not trapped between themain body16 and thefirst cover18, or the diaphragm may include one or more non-planar features, such as pleats, folds, bends, curved or convolutedportions26 or other features that facilitate flexing or movement of the untrapped portion of the diaphragm relative to the pressure andfuel chambers22,24. Thediaphragm14 may be formed of any material suitable for use in the fluid being pumped (e.g. fuel). Some representative but not limiting examples include NBR rubber (i.e. acrylonitrile butadiene rubber), NBR coated or impregnated fiber or nylon materials, polymeric films and thin metal foil or film.
• Themain body16 may include a circumferentially continuous and axially extending peripheral skirt orwall28 adapted to overlie and in assembly trap thediaphragm14 as noted above. Anintermediate wall30 may have a side facing thediaphragm14 and arranged to define part of thefuel chamber24. Adivider34 may extend from an opposite side of theintermediate wall30. Thedivider34 and opposite side may each define part of aninlet chamber38 into which fuel enters thepump10 and anoutlet chamber40 from which fuel is discharged from the pump. A first passage orport46 may be provided in theintermediate wall30 to communicate theinlet chamber38 with thefuel chamber24. Aninlet check valve48 may be associated with thefirst port46 to permit fuel flow from theinlet chamber38 to thefuel chamber24 and to prevent the reverse flow. Similarly, a second passage orport42 may be provided in theintermediate wall30 to communicate thefuel chamber24 with theoutlet chamber40. Anoutlet check valve44 may be associated with thesecond port42 to permit fuel flow from thefuel chamber24 to theoutlet chamber40 and to prevent the reverse flow. Themain body16 may include afuel inlet66 through which fuel from a fuel tank (or other fluid from a fluid source) may flow intoinlet chamber38. Themain body16 may further include afuel outlet52 through which fuel discharged from theoutlet chamber40 flows. Thefuel inlet66 andfuel outlet52 may include or comprise fittings adapted to receive a hose, tube or fluid connector to facilitate routing fuel to and from thepump10.
• Thefirst cover18 may include aperipheral rim54 adapted to be received adjacent to theperipheral wall28 of themain body16 with the periphery of thediaphragm14 trapped between therim54 andwall28. So arranged, thepressure chamber22 is defined between thefirst cover18 and thediaphragm14. Avent opening56 formed in thecover18 communicates thepressure chamber22 with avent chamber58 that is defined in an enclosure defined by achamber wall60 and thecover18 on the opposite side of the cover as thepressure chamber22. Thevent chamber58 includes aport62 leading to the atmosphere and atmospheric air flows through the vent chamber before flowing into thepressure chamber22 through thevent opening56. Likewise, air in thepressure chamber22 flows through thevent56 and then thevent chamber58 before reaching the atmosphere. Thecover18 may have any desired shape, may be formed of any desired material, and may be coupled or connected to themain body16 in any desired manner. One or more gaskets or seals64 may be received between thediaphragm14 and one or both of thefirst cover18 andmain body16 to provide a fluid tight seal between them, as desired. Thefirst cover18 may also include a pressure inlet50 that communicates a pressure source with thepressure chamber22 to vary the pressure in the pressure chamber as will be set forth below.
• In at least some implementations such as that shown inFIGS. 1-4, thepump10 may include asecond diaphragm68. Hereafter, thediaphragm14 described above will hereafter be referred to as thefirst diaphragm14 to avoid confusion with thesecond diaphragm68.
• Thesecond diaphragm68 may be carried by thehousing12 to define part of theinlet chamber38 and theoutlet chamber40. In the example shown, thesecond diaphragm68 is a generally flat and somewhat flexible sheet of material that has its periphery trapped between themain body16 and thesecond cover20 carried by or coupled to the main body. Thesecond diaphragm68 may also be trapped between thedivider34 and thesecond cover20, and a gasket orother seal70 may be provided between the second diaphragm and one or both of themain body16 andsecond cover20 to provide a fluid tight seal between them, as desired. In this way, the inlet andoutlet chambers38,40 are fluid tight and defined between thesecond cover20, thedivider34 and themain body16. If desired, aspring72 or other biasing member may be received between thesecond cover20 andsecond diaphragm68 opposite to and overlying theoutlet chamber40. Thespring72 biases the portion of thesecond diaphragm68 that is exposed to theoutlet chamber40 toward the outlet chamber. When fuel under pressure is provided under pressure into theoutlet chamber40, thespring72 may be compressed, and may subsequently provide a force on the fuel through thesecond diaphragm68 to increase the outlet pressure of fuel discharged from thefuel outlet52.
• Thesecond cover20 may include one or more vent openings. A first vent opening76 formed in thesecond cover20 communicates with afirst space78 between thesecond diaphragm68 and thesecond cover20 and overlying theinlet chamber38. A second vent opening80 formed in thesecond cover20 communicates with asecond space82 between thesecond diaphragm68 and thesecond cover20 and overlying the outlet chamber40 (e.g. the space in which thespring72 is received). The first andsecond vent openings76,80 each communicate with a separatesecond vent chamber84 and thechambers84 are defined between an enclosure orwall85 and thesecond cover20 on the opposite side of the second cover as thesecond diaphragm68. Thesecond vent chambers84 include aport86 leading to the atmosphere and thefirst space78 andsecond space82 communicate with the atmosphere through thevent openings76,80 andsecond vent chambers84. Thesecond cover20 may have any desired shape, may be formed of any desired material, and may be coupled or connected to themain body16 in any desired manner. Instead of twoseparate vent chambers84, thevent openings76,80 could both lead to a single vent chamber.
• In at least some implementations, thepump10 uses a pressure differential produced by an engine with which the pump is used to move the exposed portion of thefirst diaphragm14 relative to thefuel chamber24. This pressure differential is generally transferred via a pulse tube to thepressure chamber24 through the pressure inlet50. In a two-stroke engine the pressure inlet50 is connected to or communicated with the engine crankcase. Movement of an engine piston creates positive and negative pressure pulses that are communicated with thefirst diaphragm14 to move it relative to thefuel chamber24. As thefirst diaphragm14 moves toward thefirst cover18, the volume of thefuel chamber24 increases, a pressure drop exists across theinlet valve48 which opens to permit fuel in theinlet chamber38 to enter thefuel chamber24. Then, when the engine pressure signal changes to a positive, superatmospheric pressure (or just pressure greater than before, which could be atmospheric), thefirst diaphragm14 is displaced away from thefirst cover18. This decreases the volume of thefuel chamber24 and pushes the fuel through theoutlet valve44 and into theoutlet chamber40. Fuel in theoutlet chamber40 may exit thepump10 through thefuel outlet52, and the flow of fuel into theoutlet chamber40 may also displace the associated portion of thesecond diaphragm68 and compress thespring72. Then, when the pressure in theoutlet chamber40 reduces, thespring72 may decompress and apply a force on the fuel through thesecond diaphragm68 to assist in the discharge of fuel from theoutlet chamber40. The alternating pressure signal from the engine oscillates the exposed portion of thefirst diaphragm14 and thereby takes fuel into thefuel chamber24 and discharges fuel from the fuel chamber as noted above.
• In at least some engine applications, the pressure differential may be between about 0.5 psi and 15 psi. This pressure differential may be transferred generally directly to thefirst diaphragm14 and fuel pressures from thepump10 may be nearly the same as the pressure differential of the crankcase. In some four-stroke engines, the engine crankcase contains lubricating oil. Therefore, the pressure inlet50 is connected to or communicated with the engine intake manifold instead (although many four-stroke engines use crankcase pressure signals). As the engine piston ascends and descends, the pressure in the intake manifold transitions between approximately atmospheric pressure and a negative pressure. This pressure differential is usually less than in a two-stroke engine (e.g. about 2 psi). Because of this lower pressure differential, a spring may be added to act on thefirst diaphragm14 and move the first diaphragm when the negative pressure signal returns to approximately atmospheric pressure.
• Some engines may provide a negative biased or more negative pressure signal, and to offset this or otherwise control the movement of thefirst diaphragm14 as desired, one or more biasing members may be provided acting on the first diaphragm. In the example shown, onespring88 is provided in thefuel chamber24 between themain body16 and thefirst diaphragm14 and asecond spring90 is provided in thepressure chamber22 between thefirst cover18 andfirst diaphragm14. Thesprings88,90 provide opposing forces on thefirst diaphragm14. Thesprings88,90 may also reduce the affect of the engine pressure on thefirst diaphragm14 and assist movement of the diaphragm to provide more consistent operation of thepump10. To avoid damage to thefirst diaphragm14, spring retainers orspacers92 may be provided between thesprings88,90 and thefirst diaphragm14, as desired. The retainers orspacers92 may be fixed to the first diaphragm14 (e.g. by adhesion, weld or otherwise) or simply trapped against the diaphragm.
• Gasseous matter, such as hydrocarbon fuel vapor from the fuel in thefuel chamber24,inlet chamber38 andoutlet chamber40 may permeate through thediaphragms14,68 and escape to the atmosphere through thevent openings56,76,80. Emission to the atmosphere of at least certain vapors, or certain emission rates of vapors, may be undesirable. To reduce the emission to the atmosphere of such vapors, one or both/allvent chambers58,84 may include afilter94 designed to reduce vapor emissions. In at least one implementation, thefilter94 includes activated charcoal or the like which is known to adsorb hydrocarbon vapors. Hence, the outflow of gasses from thepressure chamber22, and first andsecond spaces78,82, may be restricted to flow through afilter94. And the inflow of air from the atmosphere into those chambers likewise occurs through thefilter94. And desorption of gasses during the inflow of air simply moves the vapors into the chambers and does not discharge the vapors to the atmosphere. Hence, the emission of vapor to the atmosphere is reduced. Thefilters94 may be carried by thepump housing12, or they may be remotely located in which case the vent openings would lead toremote vent chambers58,84 via a tube, passage or other conduit.
• Thevent chambers58,84 may be longer than they are wide to provide a relatively narrow space in which the filter material is contained and through which the gasses flow, so that the vapors are forced to engage more of the filter material before reaching thechamber port62,86 and the atmosphere. The vapor filter may also be longer than it is wide and the vapor filter may fill the volume of the vent chamber (i.e. engage the surfaces defining the vent chamber in a cross-section of the vent chamber) so that vapor must flow into the vapor filter and cannot flow around the vapor filter. This increases the likelihood that vapors will be adsorbed by the filter material and hence, increases the efficiency of thefilter94.
• In this regard,FIGS. 5 and 6 illustrate another implementation of apump100 that, includes onecircuitous vent chamber102 for thefirst vent opening104 and a secondcircuitous vent chamber106 for the second vent opening108 (these may both be called second vent chambers, or they may collectively define a single second vent chamber). These ventchambers102,106 may be separate or they may be communicated with each other (such as by a cross passage), as desired. Both ventchambers102,106 may be of similar shape and construction, or they could be different, as desired. In the version shown, thevent chambers102,106 have a circuitous interior chamber that is filled with afilter110 or filter material and that terminates at aport105,107. The circuitous path provides achamber102,106 that is more than three times as long as it is wide, and in some implementations is 8 or more times as long as it is wide, where the length is measured along a center of the circuitous chamber and the width is the average width between the walls112 that define the circuitous chamber taken generally perpendicular to the direction of gas flow in the chamber. A similar chamber or chambers may be provided for thefirst vent chamber58, if desired. Also, whileseparate vent chambers58,102,106 are shown for each vent opening56,104,108, all vent openings may all communicate with a single chamber (e.g. through tubes, passages or other conduits), or with more than two chambers, as desired. Further, an alternate second vent chamber may overlie or define at least 75% and up to the entire outer surface of thesecond cover20 and may be filled with filter material to provide an increased amount of filter material. In at least some implementations, thevent chamber port105,107 is at one end of thevent chamber102,106 and thevent openings104,108 are at the other end of the vent chamber so that gasses must flow through the entire length (or at least 75% of the length) of the vent chamber from thechamber ports105,107 to thevent openings104,108.
• As noted above, thefirst diaphragm14 and thesecond diaphragm68 may be generally planar, or they may have features to facilitate movement of exposed areas of the diaphragms for increased movement of those areas in use. In one form, as shown inFIGS. 7-10, a flat, planar piece of diaphragm material150 (FIG. 7) is formed into a diaphragm152 (FIGS. 9 and 10) with an offset, non-planar and generallyfrustoconical pump portion154 by stretching or otherwise forming theflat sheet150 so that at least some of thepump portion154 of the diaphragm152 (e.g. the portion exposed within the pump in assembly) is offset from aperipheral rim156 portion of the diaphragm. The diaphragm may be formed from any suitable material such as polyamides, polyesters, fluoropolymers, polyacetals, polyethylenes, or alloys or copolymers thereof, and thin metal films or sheets such as stainless steel. Some more specific examples include, semi-crystalline plastics, nylon 6,6, polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), polyethylene terephthalate (PET) (e.g., Mylar by Dupont), polyoxymethylene (POM), low-density polyethylene (LDPE), or ethylene vinyl alcohol (EVOH). Polymeric materials may optionally include fillers or modifiers such as colorants, stabilizers, reinforcements, electrical conductors, etc. Thediaphragm152 may have a thickness between about 0.02 mm to 0.8 mm.
• The frustoconical shape of theexample diaphragm152 includes a generallyflat center region158 that is at the farthest offset distance from therim156, and atapered sidewall160 that extends from a maximum diameter adjacent to therim156 to a minimum diameter at thecenter region158. Theflat center region158 may facilitate use of a spring with thediaphragm152 after the diaphragm is formed. Of course, other shapes and configurations may be used. For example, folds, bends or other non-planar features may be provided in thediaphragm152 by the stretching or other formation methods. The non-planar regions facilitate flexing and movement of the portion of thediaphragm152 exposed to the pressure/force differential to improve the pumping action of the diaphragm.
• In one form, the sheet of material is trapped about its periphery betweenopposed clamps160 and a central formingmember162 is pressed into the unclamped and exposed center of thesheet150 and advanced until the material stretches and plastically deforms, without rupturing. In the example shown, the formingmember162 is a round disc having a diameter less than an interior diameter of theclamps160 and adapted to define theflat center region158 in the formeddiaphragm152. The plastically formed material retains at least some of the non-planar shape achieved during the forming process (i.e. there may also be some elastic deformation and the material may resiliently return at least partly toward its planar and unformed condition). In addition to or instead of the forming member, a fluid pressure (gas or liquid or both) may be applied to a portion of the diaphragm to be stretched or otherwise deformed out of its planar and unformed condition.
• Prior diaphragms often included an enlarged bead at the periphery of the diaphragm. The bead was received within a circular channel in one or both of the cover and main body of the pump housing to retain the position of the diaphragm relative to the housing in use of the pump. With adiaphragm152 having aflat rim156 adapted to be trapped between themain body16 and acover18, as shown inFIGS. 7-12, there is no bead or other non-planar retention feature. Accordingly, thediaphragm152 set forth herein, which may be entirely planar as shown inFIG. 7 or include at least onenon-planar portion154 as shown inFIGS. 8-12, may include retention features164 within theplanar rim156. In the example shown, the retention features are defined byvoids164 formed in therim156. Thevoids164 do not increase the thickness or render therim156 non-planar. Instead, as shown inFIG. 12, thevoids164 provide an open area into which a gasket or seal166 may protrude in assembly, when thecover18 andmain body16 are connected together with the gasket/seal166 anddiaphragm152 trapped between them. This mechanically interconnects or interlocks thediaphragm152 with the gasket orseal166, and the position of thediaphragm152 may be maintained in use of the pump. In the implementation shown inFIGS. 11 and 12, a pair ofgaskets166 are used, with a gasket on each side of therim156. In this arrangement, thegaskets166 may engage each other through thevoids164, providing improved retention of thediaphragm152 relative to thegaskets166. A plurality ofvoids164 may be provided spaced apart circumferentially about therim156, as desired. Further, thevoids164 may have any desired shape and size. In the example shown, thevoids164 are circular and of uniform spacing and uniform size, but these details are not required and may be changed as desired.
• FIG. 13 illustrates another example of adiaphragm170 including a generallyplanar rim172 to be trapped between amain body173 and a cover (not shown) of apump174. Thediaphragm170 may be either planar or non-planar, as desired. The example shown is the second diaphragm (corresponding to diaphragm68 inFIGS. 1-4), which spans or covers theinlet chamber38 andoutlet chamber40, as well as thedivider34, although the concepts discussed herein could also be applied to thefirst diaphragm14.Voids176 are provided in therim172 and are of a size, shape and location to receive locator tabs or pins178 extending from themain body16, cover18 or both. The position of thediaphragm170 is then retained relative to themain body173 in assembly. Further, agasket180 may be trapped between thediaphragm170 and themain body173, cover or both. Thegasket180 may also include aperipheral rim182 and one ormore voids184 may be formed in therim182 and be of a size, shape and location to receive a locator tab or pin178 to retain the position of thegasket180. Thegasket180 and thediaphragm170 may be separate components which facilitates the manufacture of each of them. Thediaphragm170 andgasket180 may be combined together before assembly (e.g. by an adhesive, weld, connector or the like), or they may be separately installed into thepump174, as desired. Some prior diaphragms formed from thin film polymers were overmolded with a rubber gasket but it was found to be difficult to cure the rubber gasket without damaging or changing the properties of the film, it was difficult to form the rubber gasket without burrs or other imperfections than can affect the performance of the gasket and diaphragm, and burrs or pieces of the gasket may come loose in the pump.
• FIG. 14 illustrates adiaphragm pump200 that may be similar in many aspects to the previously described pumps, and to facilitate description of this pump, similar components have been given the same reference numbers used in description of the other pumps. For example, the pump may include ahousing12 with amain body16, afirst cover18, asecond cover20, and afirst diaphragm202 trapped about its periphery between themain body16 andfirst cover18, and asecond diaphragm68 trapped about its periphery between themain body16 andsecond cover20. The first and second covers18,20 may be coupled to themain body16 in any suitable way, such as by fasteners or welding the bodies together.
• As shown inFIGS. 15 and 16, thefirst diaphragm202 may include abead204 at or adjacent to its periphery. Thebead204 may be circumferentially continuous and of any desired cross-sectional shape, such as circular or elliptical, although other shapes may be used and the bead need not have a constant shape about its circumferential length. Thebead204 may be adapted to be received betweenopposed surfaces206,208 of themain body16 andfirst cover18. One or both of theopposed surfaces206,208 of the first cover and main body may include annular channels, indentations or other features designed to increase the surface area of contact between thefirst diaphragm bead204 and themain body16 andfirst cover18 to provide improved retention of thefirst diaphragm202 and to provide an improved seal between thebodies16,18 and202.
• Asidewall210 of thediaphragm202 extends radially inwardly from thebead204. Thesidewall210 may be contoured as desired to provide a desired flexibility of thediaphragm202 and/or permit a desired range of movement of the untrapped portion of the diaphragm (which is the portion not trapped between thefirst cover18 and main body16) relative to the trapped portion. In the implementation shown, and when viewed from the top side of thediaphragm202 as shown inFIG. 15, thesidewall210 includes a flat or concavefirst portion212 that is coupled to thebead204 and which leads to a convex inner orsecond portion214 providing a generally sinuous or ‘s-shaped’ sidewall. Thesecond portion214 may be generally frustoconical or otherwise shaped, and may lead to acentral portion216. Thecentral portion216 may be generally planar, if desired, to provide a flat surface against which one ormore springs88,90 may act, as previously described.
• Thefirst diaphragm202 may include or be formed from multiple layers of material, and at least two layers may be formed from different materials. In at least some implementations, including the example shown inFIG. 16, the diaphragm may include more than two layers. As shown inFIG. 16, the diaphragm includes three layers with twoouter layers218,220 and amiddle layer222 between the outer layers. At least one of the layers218-222 may be formed from a material that inhibits fuel vapor permeation therethrough, to inhibit or prevent fuel vapor permeation through the first diaphragm. In the example shown, themiddle layer222 is formed from a fuel vapor barrier material. Representative but not limiting examples of fuel vapor barrier materials include, fluoropolymers (including but not limited to perfluoroalkoxy (PFA), polyfluoroethylenepropylene (FEP), polytetrafluoroethylene (PTFE)), liquid crystal polymers, nylons, polymeric films, thin metal foil or film, and ethylene vinyl alcohol.
• Theouter layers218,220 may be formed from any desired material which may be chosen, for example, to resist degradation in liquid fuel (at least for the side exposed to the fuel chamber), to resist degradation due to abrasion or contact with thefirst cover18 ormain body16, to resist degradation due to contact with the spring(s) or retainers for the springs, to facilitate movement of the untrapped portion of the diaphragm, to facilitate formation of the diaphragm and/or to reduce the cost of the diaphragm. Some representative but not limiting examples of materials for the outer layers include NBR rubber (i.e. acrylonitrile butadiene rubber), H-NBR, NBR coated or impregnated fiber or nylon materials, or various fluoroelastomers. In one implementation, theouter layers218,220 are formed of NBR and themiddle layer222 is formed from PFA.
• In at least some implementations, themiddle layer222 may be fully encapsulated by theouter layers218,220, at least in the untrapped area of thediaphragm202. Further, opposed sides orsurfaces224,226 of thebead204 may be defined by the material of the outer layers to facilitate sealing engagement with thefirst cover18 andmain body16. Theouter layers218,220 may be adhered to theinner layer222 or the inner layer may be overmolded by the material defining the outer layers. With some materials, bonding of the inner and outer layers218-222 can be problematic so an adhesive may be used even when theinner layer222 is overmolded with the material of theouter layers218,220. While described above with regard to thefirst diaphragm202, thesecond diaphragm68 may be formed in a similar manner.
• FIGS. 17 and 18 illustrate analternate diaphragm250 having more than one layer and which may have any desired shape, including that described above with regard todiaphragm202. As shown, thediaphragm250 includes two layers, each formed of a different material. Afirst layer252 may be formed from a material described above with regard to theouter layers218,220, and thesecond layer254 may be formed from a material described above with regard to theinner layer222. In at least some implementations, when thediaphragm250 is installed in a pump, thesecond layer254 is exposed to liquid fuel in thefuel chamber24 and thefirst layer252 is exposed to thepressure chamber22. Of course, the opposite could be true if desired. At least thesecond layer254 inhibits or prevents fuel vapor from permeating through thediaphragm250. Thesecond layer254 may be continuous, that is, without voids, to provide a continuous barrier against fuel vapor permeation. And the second layer may span the entirety of at least the untrapped portion of thediaphragm250. In at least some implementations, thesecond layer254 is trapped between thefirst layer252 and either themain body16 or first cover18 (depending upon the orientation of thediaphragm250 within the pump). A periphery of thesecond layer254 may instead be embedded within abead256 which, in some implementations, may be formed from the material of thefirst layer252 so that the bead is trapped between thefirst cover18 andmain body16 to seal thediaphragm250 to the first cover and main body. Alternatively, as shown inFIGS. 17 and 18, thebead256 can be formed by the material of bothlayers252,254. Of course, one or more gaskets may also be used between thediaphragm250 and thefirst cover18 and/ormain body16, if desired. In applications where a sufficient seal is achieved with the diaphragm alone, without any gaskets, the part count is reduced and handling and assembly of the components is facilitated.
• Instead or in addition to the configurations and constructions noted herein, in a single layer or multiple layer diaphragm, one or both sides of the diaphragm may include a base material or layer that is coated with a material or substance to inhibit fuel vapor permeation through the diaphragm. In at least some implementations, at least part of the diaphragm may be covered with a fluorine coating. In the example of a two-layer diaphragm as inFIGS. 17 and 18, the entire diaphragm or only the first layer of the diaphragm may be coated. Alternatively, the diaphragm may be formed from or include a fluoroelastomer like FKM, FFKM or FEPM.
• While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention. For example, while the vent chamber ports were noted as communicating with the atmosphere, they may communicate with any ambient or outside chamber, where outside is taken to mean some space not internal to the pump.

Claims (22)

1. A diaphragm for a fluid pump, comprising:

a first layer formed from a first material that inhibits or prevents vapor permeation through the diaphragm; and

a second layer coupled to the first layer and formed from a second material different than the first material.

2. The diaphragm ofclaim 1 wherein the first material includes at least one of fluoropolymers, perfluoroalkoxy (PFA), polyfluoroethylenepropylene (FEP), polytetrafluoroethylene (PTFE), liquid crystal polymers, nylons, thin metal foil or film, or ethylene vinyl alcohol.

3. The diaphragm ofclaim 2 wherein the second material includes at least one of NBR rubber, H-NBR, NBR coated or impregnated fiber or nylon materials, or a fluoroelastomer.

4. The diaphragm ofclaim 2 which also comprises a third layer and wherein the first layer is received between the second and third layer.

5. The diaphragm ofclaim 4 wherein the third layer is formed from the second material.

6. The diaphragm ofclaim 4 wherein the second layer and third layer are both overmolded on the first layer.

7. The diaphragm ofclaim 4 wherein the first layer is fully encapsulated between the second and third layer.

8. The diaphragm ofclaim 4 wherein the second and third layers each include a first portion adapted to be trapped between opposed bodies and the second and third layers each also include a second portion inboard of the first portion and wherein the first layer is fully encapsulated between the second portions of the second and third layers.

9. The diaphragm ofclaim 1 wherein the first layer is continuous and without perforations in an area of the diaphragm adapted to be exposed to a fluid.

10. The diaphragm ofclaim 1 wherein the first layer includes a base material and a coating that prevents vapor permeation therethrough.

11. The diaphragm ofclaim 2 wherein the fluoropolymer is a fluoroelastomer.

12. A fluid pump, comprising:

a housing having a vent opening;

a diaphragm carried by the housing and defining with the housing a fluid chamber for receipt of a fluid, wherein the fuel chamber is on one side of the diaphragm and the vent opening is on the other side of the diaphragm such that liquid fuel does not flow through the vent opening; and

a vent chamber communicated with the vent opening and including a vapor filter, the vapor chamber and vapor filter being arranged so that fluid flowing out of the vapor vent flows through the vapor filter.

13. The fluid pump ofclaim 12 wherein the vapor filter includes charcoal.

14. The fluid pump ofclaim 12 wherein the housing includes multiple vent openings and each vent opening is communicated with one or more than one vapor filter.

15. The fluid pump ofclaim 12 wherein the vent chamber is longer than it is wide and wherein the vapor filter is longer than it is wide and the vapor filter fills the width of the vent chamber so that vapor must flow into the vapor filter and cannot flow around the vapor filter.

16. The fluid pump ofclaim 15 wherein the vent chamber is more than 3 times as long as it is wide.

17. The fluid pump ofclaim 15 wherein the vent chamber has more than one change of direction and is circuitous.

18. A diaphragm for a fluid pump, comprising:

a planar rim, a center region inboard of the rim and multiple retention features formed in the rim.

19. The diaphragm ofclaim 18 wherein the retention features include voids formed through the rim and circumferentially spaced apart about the rim.

20. (canceled)

21. (canceled)

22. (canceled)

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