U.S. patent application number 16/322247 was filed with the patent office on 2019-05-30 for fluid driven diaphragm pump.
The applicant listed for this patent is Walbro LLC. Invention is credited to Katsuaki Hamataka, Nobuyuki Kuroki, Mark S. Swanson, Tetsuya Takahashi, Teruhiko Tobinai.
Application Number | 20190162177 16/322247 |
Document ID | / |
Family ID | 61073141 |
Filed Date | 2019-05-30 |
United States Patent
Application |
20190162177 |
Kind Code |
A1 |
Kuroki; Nobuyuki ; et
al. |
May 30, 2019 |
FLUID DRIVEN DIAPHRAGM PUMP
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.
Inventors: |
Kuroki; Nobuyuki;
(Sendai?City, JP) ; Hamataka; Katsuaki;
(Sendai-City, JP) ; Swanson; Mark S.; (Concord,
NC) ; Takahashi; Tetsuya; (Shibata-Gun, JP) ;
Tobinai; Teruhiko; (Sendai?City, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Walbro LLC |
Tucson |
AZ |
US |
|
|
Family ID: |
61073141 |
Appl. No.: |
16/322247 |
Filed: |
August 1, 2017 |
PCT Filed: |
August 1, 2017 |
PCT NO: |
PCT/US2017/044837 |
371 Date: |
January 31, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62369541 |
Aug 1, 2016 |
|
|
|
62474136 |
Mar 21, 2017 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02M 37/12 20130101;
F04B 43/06 20130101; F04B 43/0054 20130101; F02M 37/04 20130101;
F04B 53/06 20130101; F02M 17/04 20130101 |
International
Class: |
F04B 43/06 20060101
F04B043/06; F04B 43/00 20060101 F04B043/00 |
Claims
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 of claim 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 of claim 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 of claim 2 which also comprises a third layer and
wherein the first layer is received between the second and third
layer.
5. The diaphragm of claim 4 wherein the third layer is formed from
the second material.
6. The diaphragm of claim 4 wherein the second layer and third
layer are both overmolded on the first layer.
7. The diaphragm of claim 4 wherein the first layer is fully
encapsulated between the second and third layer.
8. The diaphragm of claim 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 of claim 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 of claim 1 wherein the first layer includes a
base material and a coating that prevents vapor permeation
therethrough.
11. The diaphragm of claim 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 of claim 12 wherein the vapor filter includes
charcoal.
14. The fluid pump of claim 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 of claim 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 of claim 15 wherein the vent chamber is more
than 3 times as long as it is wide.
17. The fluid pump of claim 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 of claim 18 wherein the retention features
include voids formed through the rim and circumferentially spaced
apart about the rim.
20. (canceled)
21. (canceled)
22. (canceled)
Description
REFERENCE TO RELATED APPLICATIONS
[0001] 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
[0002] The present disclosure relates generally to a fluid driven
diaphragm pump.
BACKGROUND
[0003] 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
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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
[0011] The following detailed description of certain embodiments
and best mode will be set forth with reference to the accompanying
drawings, in which:
[0012] FIG. 1 is a side view of a fluid driven pump;
[0013] FIG. 2 is a bottom view of the pump of FIG. 1;
[0014] FIG. 3 is a top view of the pump;
[0015] FIG. 4 is a cross-sectional view of the pump taking
generally along line 4-4 in FIG. 3;
[0016] FIG. 5 is a bottom view of the pump with an alternate vent
cavity;
[0017] FIG. 6 is a cross-sectional view of the pump of FIG. 5;
[0018] FIG. 7 is a perspective view of a sheet of material for a
diaphragm;
[0019] FIG. 8 is a perspective sectional view of part of a forming
mechanism for forming a diaphragm from the material of FIG. 7;
[0020] FIG. 9 is a perspective sectional view of a formed
diaphragm;
[0021] FIG. 10 is a perspective view of the formed diaphragm;
[0022] FIG. 11 is a sectional view of a pump;
[0023] FIG. 12 is an enlarged view of the encircled portion of FIG.
11;
[0024] FIG. 13 is an exploded view of a portion of a pump showing a
diaphragm, gasket and part of a pump housing;
[0025] FIG. 14 is a cross-sectional view of a pump including a
first diaphragm;
[0026] FIG. 15 is a plan view of the first diaphragm;
[0027] FIG. 16 is an enlarged cross-sectional view of a portion of
the first diaphragm illustrating a multi-layer construction;
[0028] FIG. 17 is a perspective view showing one side of a
multi-layer diaphragm; and
[0029] FIG. 18 is a perspective view showing the other side of the
diaphragm of FIG. 17.
DETAILED DESCRIPTION
[0030] Referring in more detail to the drawings, FIGS. 1-4
illustrate a fluid driven diaphragm pump 10 that may be used, for
example, to pump fuel from one location to another in a fuel
system. In at least one implementation, the pump 10 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 the pump 10 is described
herein with regard to pumping fuel, it may be used to pump other
fluids.
[0031] The pump 10 includes a housing 12 and at least one pump
diaphragm 14 (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. The housing 12 may include a main body
16 and one or more covers with a first cover 18 and a second cover
20 shown in the illustrated example. The diaphragm 14 may be a
generally thin sheet of material that is flexible, and, as shown in
FIG. 4, the diaphragm may be trapped about its periphery between
the main body 16 and first cover 18. So arranged, a pressure
chamber 22 is defined between one side of the diaphragm 14 and the
first cover 18, and a fuel chamber 24 is defined between the
opposite side of the diaphragm 14 and the main body 16. The
diaphragm 14 may be generally planar and suitably elastic to permit
movement of at least part of the diaphragm not trapped between the
main body 16 and the first cover 18, or the diaphragm may include
one or more non-planar features, such as pleats, folds, bends,
curved or convoluted portions 26 or other features that facilitate
flexing or movement of the untrapped portion of the diaphragm
relative to the pressure and fuel chambers 22, 24. The diaphragm 14
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.
[0032] The main body 16 may include a circumferentially continuous
and axially extending peripheral skirt or wall 28 adapted to
overlie and in assembly trap the diaphragm 14 as noted above. An
intermediate wall 30 may have a side facing the diaphragm 14 and
arranged to define part of the fuel chamber 24. A divider 34 may
extend from an opposite side of the intermediate wall 30. The
divider 34 and opposite side may each define part of an inlet
chamber 38 into which fuel enters the pump 10 and an outlet chamber
40 from which fuel is discharged from the pump. A first passage or
port 46 may be provided in the intermediate wall 30 to communicate
the inlet chamber 38 with the fuel chamber 24. An inlet check valve
48 may be associated with the first port 46 to permit fuel flow
from the inlet chamber 38 to the fuel chamber 24 and to prevent the
reverse flow. Similarly, a second passage or port 42 may be
provided in the intermediate wall 30 to communicate the fuel
chamber 24 with the outlet chamber 40. An outlet check valve 44 may
be associated with the second port 42 to permit fuel flow from the
fuel chamber 24 to the outlet chamber 40 and to prevent the reverse
flow. The main body 16 may include a fuel inlet 66 through which
fuel from a fuel tank (or other fluid from a fluid source) may flow
into inlet chamber 38. The main body 16 may further include a fuel
outlet 52 through which fuel discharged from the outlet chamber 40
flows. The fuel inlet 66 and fuel outlet 52 may include or comprise
fittings adapted to receive a hose, tube or fluid connector to
facilitate routing fuel to and from the pump 10.
[0033] The first cover 18 may include a peripheral rim 54 adapted
to be received adjacent to the peripheral wall 28 of the main body
16 with the periphery of the diaphragm 14 trapped between the rim
54 and wall 28. So arranged, the pressure chamber 22 is defined
between the first cover 18 and the diaphragm 14. A vent opening 56
formed in the cover 18 communicates the pressure chamber 22 with a
vent chamber 58 that is defined in an enclosure defined by a
chamber wall 60 and the cover 18 on the opposite side of the cover
as the pressure chamber 22. The vent chamber 58 includes a port 62
leading to the atmosphere and atmospheric air flows through the
vent chamber before flowing into the pressure chamber 22 through
the vent opening 56. Likewise, air in the pressure chamber 22 flows
through the vent 56 and then the vent chamber 58 before reaching
the atmosphere. The cover 18 may have any desired shape, may be
formed of any desired material, and may be coupled or connected to
the main body 16 in any desired manner. One or more gaskets or
seals 64 may be received between the diaphragm 14 and one or both
of the first cover 18 and main body 16 to provide a fluid tight
seal between them, as desired. The first cover 18 may also include
a pressure inlet 50 that communicates a pressure source with the
pressure chamber 22 to vary the pressure in the pressure chamber as
will be set forth below.
[0034] In at least some implementations such as that shown in FIGS.
1-4, the pump 10 may include a second diaphragm 68. Hereafter, the
diaphragm 14 described above will hereafter be referred to as the
first diaphragm 14 to avoid confusion with the second diaphragm
68.
[0035] The second diaphragm 68 may be carried by the housing 12 to
define part of the inlet chamber 38 and the outlet chamber 40. In
the example shown, the second diaphragm 68 is a generally flat and
somewhat flexible sheet of material that has its periphery trapped
between the main body 16 and the second cover 20 carried by or
coupled to the main body. The second diaphragm 68 may also be
trapped between the divider 34 and the second cover 20, and a
gasket or other seal 70 may be provided between the second
diaphragm and one or both of the main body 16 and second cover 20
to provide a fluid tight seal between them, as desired. In this
way, the inlet and outlet chambers 38, 40 are fluid tight and
defined between the second cover 20, the divider 34 and the main
body 16. If desired, a spring 72 or other biasing member may be
received between the second cover 20 and second diaphragm 68
opposite to and overlying the outlet chamber 40. The spring 72
biases the portion of the second diaphragm 68 that is exposed to
the outlet chamber 40 toward the outlet chamber. When fuel under
pressure is provided under pressure into the outlet chamber 40, the
spring 72 may be compressed, and may subsequently provide a force
on the fuel through the second diaphragm 68 to increase the outlet
pressure of fuel discharged from the fuel outlet 52.
[0036] The second cover 20 may include one or more vent openings. A
first vent opening 76 formed in the second cover 20 communicates
with a first space 78 between the second diaphragm 68 and the
second cover 20 and overlying the inlet chamber 38. A second vent
opening 80 formed in the second cover 20 communicates with a second
space 82 between the second diaphragm 68 and the second cover 20
and overlying the outlet chamber 40 (e.g. the space in which the
spring 72 is received). The first and second vent openings 76, 80
each communicate with a separate second vent chamber 84 and the
chambers 84 are defined between an enclosure or wall 85 and the
second cover 20 on the opposite side of the second cover as the
second diaphragm 68. The second vent chambers 84 include a port 86
leading to the atmosphere and the first space 78 and second space
82 communicate with the atmosphere through the vent openings 76, 80
and second vent chambers 84. The second cover 20 may have any
desired shape, may be formed of any desired material, and may be
coupled or connected to the main body 16 in any desired manner.
Instead of two separate vent chambers 84, the vent openings 76, 80
could both lead to a single vent chamber.
[0037] In at least some implementations, the pump 10 uses a
pressure differential produced by an engine with which the pump is
used to move the exposed portion of the first diaphragm 14 relative
to the fuel chamber 24. This pressure differential is generally
transferred via a pulse tube to the pressure chamber 24 through the
pressure inlet 50. In a two-stroke engine the pressure inlet 50 is
connected to or communicated with the engine crankcase. Movement of
an engine piston creates positive and negative pressure pulses that
are communicated with the first diaphragm 14 to move it relative to
the fuel chamber 24. As the first diaphragm 14 moves toward the
first cover 18, the volume of the fuel chamber 24 increases, a
pressure drop exists across the inlet valve 48 which opens to
permit fuel in the inlet chamber 38 to enter the fuel chamber 24.
Then, when the engine pressure signal changes to a positive,
superatmospheric pressure (or just pressure greater than before,
which could be atmospheric), the first diaphragm 14 is displaced
away from the first cover 18. This decreases the volume of the fuel
chamber 24 and pushes the fuel through the outlet valve 44 and into
the outlet chamber 40. Fuel in the outlet chamber 40 may exit the
pump 10 through the fuel outlet 52, and the flow of fuel into the
outlet chamber 40 may also displace the associated portion of the
second diaphragm 68 and compress the spring 72. Then, when the
pressure in the outlet chamber 40 reduces, the spring 72 may
decompress and apply a force on the fuel through the second
diaphragm 68 to assist in the discharge of fuel from the outlet
chamber 40. The alternating pressure signal from the engine
oscillates the exposed portion of the first diaphragm 14 and
thereby takes fuel into the fuel chamber 24 and discharges fuel
from the fuel chamber as noted above.
[0038] 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 the first
diaphragm 14 and fuel pressures from the pump 10 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 inlet 50 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 the first
diaphragm 14 and move the first diaphragm when the negative
pressure signal returns to approximately atmospheric pressure.
[0039] Some engines may provide a negative biased or more negative
pressure signal, and to offset this or otherwise control the
movement of the first diaphragm 14 as desired, one or more biasing
members may be provided acting on the first diaphragm. In the
example shown, one spring 88 is provided in the fuel chamber 24
between the main body 16 and the first diaphragm 14 and a second
spring 90 is provided in the pressure chamber 22 between the first
cover 18 and first diaphragm 14. The springs 88, 90 provide
opposing forces on the first diaphragm 14. The springs 88, 90 may
also reduce the affect of the engine pressure on the first
diaphragm 14 and assist movement of the diaphragm to provide more
consistent operation of the pump 10. To avoid damage to the first
diaphragm 14, spring retainers or spacers 92 may be provided
between the springs 88, 90 and the first diaphragm 14, as desired.
The retainers or spacers 92 may be fixed to the first diaphragm 14
(e.g. by adhesion, weld or otherwise) or simply trapped against the
diaphragm.
[0040] Gasseous matter, such as hydrocarbon fuel vapor from the
fuel in the fuel chamber 24, inlet chamber 38 and outlet chamber 40
may permeate through the diaphragms 14, 68 and escape to the
atmosphere through the vent openings 56, 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/all vent chambers 58, 84 may
include a filter 94 designed to reduce vapor emissions. In at least
one implementation, the filter 94 includes activated charcoal or
the like which is known to adsorb hydrocarbon vapors. Hence, the
outflow of gasses from the pressure chamber 22, and first and
second spaces 78, 82, may be restricted to flow through a filter
94. And the inflow of air from the atmosphere into those chambers
likewise occurs through the filter 94. 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. The filters 94 may
be carried by the pump housing 12, or they may be remotely located
in which case the vent openings would lead to remote vent chambers
58, 84 via a tube, passage or other conduit.
[0041] The vent chambers 58, 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 the
chamber port 62, 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 the filter
94.
[0042] In this regard, FIGS. 5 and 6 illustrate another
implementation of a pump 100 that, includes one circuitous vent
chamber 102 for the first vent opening 104 and a second circuitous
vent chamber 106 for the second vent opening 108 (these may both be
called second vent chambers, or they may collectively define a
single second vent chamber). These vent chambers 102, 106 may be
separate or they may be communicated with each other (such as by a
cross passage), as desired. Both vent chambers 102, 106 may be of
similar shape and construction, or they could be different, as
desired. In the version shown, the vent chambers 102, 106 have a
circuitous interior chamber that is filled with a filter 110 or
filter material and that terminates at a port 105, 107. The
circuitous path provides a chamber 102, 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 walls 112 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
the first vent chamber 58, if desired. Also, while separate vent
chambers 58, 102, 106 are shown for each vent opening 56, 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 the second cover 20 and may be filled with filter material to
provide an increased amount of filter material. In at least some
implementations, the vent chamber port 105, 107 is at one end of
the vent chamber 102, 106 and the vent openings 104, 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 the chamber ports 105, 107 to the vent openings 104, 108.
[0043] As noted above, the first diaphragm 14 and the second
diaphragm 68 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 in
FIGS. 7-10, a flat, planar piece of diaphragm material 150 (FIG. 7)
is formed into a diaphragm 152 (FIGS. 9 and 10) with an offset,
non-planar and generally frustoconical pump portion 154 by
stretching or otherwise forming the flat sheet 150 so that at least
some of the pump portion 154 of the diaphragm 152 (e.g. the portion
exposed within the pump in assembly) is offset from a peripheral
rim 156 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. The
diaphragm 152 may have a thickness between about 0.02 mm to 0.8
mm.
[0044] The frustoconical shape of the example diaphragm 152
includes a generally flat center region 158 that is at the farthest
offset distance from the rim 156, and a tapered sidewall 160 that
extends from a maximum diameter adjacent to the rim 156 to a
minimum diameter at the center region 158. The flat center region
158 may facilitate use of a spring with the diaphragm 152 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 the diaphragm 152 by the stretching or other
formation methods. The non-planar regions facilitate flexing and
movement of the portion of the diaphragm 152 exposed to the
pressure/force differential to improve the pumping action of the
diaphragm.
[0045] In one form, the sheet of material is trapped about its
periphery between opposed clamps 160 and a central forming member
162 is pressed into the unclamped and exposed center of the sheet
150 and advanced until the material stretches and plastically
deforms, without rupturing. In the example shown, the forming
member 162 is a round disc having a diameter less than an interior
diameter of the clamps 160 and adapted to define the flat center
region 158 in the formed diaphragm 152. 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.
[0046] 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 a diaphragm 152 having a flat rim
156 adapted to be trapped between the main body 16 and a cover 18,
as shown in FIGS. 7-12, there is no bead or other non-planar
retention feature. Accordingly, the diaphragm 152 set forth herein,
which may be entirely planar as shown in FIG. 7 or include at least
one non-planar portion 154 as shown in FIGS. 8-12, may include
retention features 164 within the planar rim 156. In the example
shown, the retention features are defined by voids 164 formed in
the rim 156. The voids 164 do not increase the thickness or render
the rim 156 non-planar. Instead, as shown in FIG. 12, the voids 164
provide an open area into which a gasket or seal 166 may protrude
in assembly, when the cover 18 and main body 16 are connected
together with the gasket/seal 166 and diaphragm 152 trapped between
them. This mechanically interconnects or interlocks the diaphragm
152 with the gasket or seal 166, and the position of the diaphragm
152 may be maintained in use of the pump. In the implementation
shown in FIGS. 11 and 12, a pair of gaskets 166 are used, with a
gasket on each side of the rim 156. In this arrangement, the
gaskets 166 may engage each other through the voids 164, providing
improved retention of the diaphragm 152 relative to the gaskets
166. A plurality of voids 164 may be provided spaced apart
circumferentially about the rim 156, as desired. Further, the voids
164 may have any desired shape and size. In the example shown, the
voids 164 are circular and of uniform spacing and uniform size, but
these details are not required and may be changed as desired.
[0047] FIG. 13 illustrates another example of a diaphragm 170
including a generally planar rim 172 to be trapped between a main
body 173 and a cover (not shown) of a pump 174. The diaphragm 170
may be either planar or non-planar, as desired. The example shown
is the second diaphragm (corresponding to diaphragm 68 in FIGS.
1-4), which spans or covers the inlet chamber 38 and outlet chamber
40, as well as the divider 34, although the concepts discussed
herein could also be applied to the first diaphragm 14. Voids 176
are provided in the rim 172 and are of a size, shape and location
to receive locator tabs or pins 178 extending from the main body
16, cover 18 or both. The position of the diaphragm 170 is then
retained relative to the main body 173 in assembly. Further, a
gasket 180 may be trapped between the diaphragm 170 and the main
body 173, cover or both. The gasket 180 may also include a
peripheral rim 182 and one or more voids 184 may be formed in the
rim 182 and be of a size, shape and location to receive a locator
tab or pin 178 to retain the position of the gasket 180. The gasket
180 and the diaphragm 170 may be separate components which
facilitates the manufacture of each of them. The diaphragm 170 and
gasket 180 may be combined together before assembly (e.g. by an
adhesive, weld, connector or the like), or they may be separately
installed into the pump 174, 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.
[0048] FIG. 14 illustrates a diaphragm pump 200 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 a housing 12 with a main
body 16, a first cover 18, a second cover 20, and a first diaphragm
202 trapped about its periphery between the main body 16 and first
cover 18, and a second diaphragm 68 trapped about its periphery
between the main body 16 and second cover 20. The first and second
covers 18, 20 may be coupled to the main body 16 in any suitable
way, such as by fasteners or welding the bodies together.
[0049] As shown in FIGS. 15 and 16, the first diaphragm 202 may
include a bead 204 at or adjacent to its periphery. The bead 204
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. The bead 204 may be adapted
to be received between opposed surfaces 206, 208 of the main body
16 and first cover 18. One or both of the opposed surfaces 206, 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 the first diaphragm bead 204 and the main
body 16 and first cover 18 to provide improved retention of the
first diaphragm 202 and to provide an improved seal between the
bodies 16, 18 and 202.
[0050] A sidewall 210 of the diaphragm 202 extends radially
inwardly from the bead 204. The sidewall 210 may be contoured as
desired to provide a desired flexibility of the diaphragm 202
and/or permit a desired range of movement of the untrapped portion
of the diaphragm (which is the portion not trapped between the
first cover 18 and main body 16) relative to the trapped portion.
In the implementation shown, and when viewed from the top side of
the diaphragm 202 as shown in FIG. 15, the sidewall 210 includes a
flat or concave first portion 212 that is coupled to the bead 204
and which leads to a convex inner or second portion 214 providing a
generally sinuous or `s-shaped` sidewall. The second portion 214
may be generally frustoconical or otherwise shaped, and may lead to
a central portion 216. The central portion 216 may be generally
planar, if desired, to provide a flat surface against which one or
more springs 88, 90 may act, as previously described.
[0051] The first diaphragm 202 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 in FIG. 16, the diaphragm may include
more than two layers. As shown in FIG. 16, the diaphragm includes
three layers with two outer layers 218, 220 and a middle layer 222
between the outer layers. At least one of the layers 218-222 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, the middle layer 222 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.
[0052] The outer layers 218, 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 the first cover
18 or main body 16, 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, the outer layers
218, 220 are formed of NBR and the middle layer 222 is formed from
PFA.
[0053] In at least some implementations, the middle layer 222 may
be fully encapsulated by the outer layers 218, 220, at least in the
untrapped area of the diaphragm 202. Further, opposed sides or
surfaces 224, 226 of the bead 204 may be defined by the material of
the outer layers to facilitate sealing engagement with the first
cover 18 and main body 16. The outer layers 218, 220 may be adhered
to the inner layer 222 or the inner layer may be overmolded by the
material defining the outer layers. With some materials, bonding of
the inner and outer layers 218-222 can be problematic so an
adhesive may be used even when the inner layer 222 is overmolded
with the material of the outer layers 218, 220. While described
above with regard to the first diaphragm 202, the second diaphragm
68 may be formed in a similar manner.
[0054] FIGS. 17 and 18 illustrate an alternate diaphragm 250 having
more than one layer and which may have any desired shape, including
that described above with regard to diaphragm 202. As shown, the
diaphragm 250 includes two layers, each formed of a different
material. A first layer 252 may be formed from a material described
above with regard to the outer layers 218, 220, and the second
layer 254 may be formed from a material described above with regard
to the inner layer 222. In at least some implementations, when the
diaphragm 250 is installed in a pump, the second layer 254 is
exposed to liquid fuel in the fuel chamber 24 and the first layer
252 is exposed to the pressure chamber 22. Of course, the opposite
could be true if desired. At least the second layer 254 inhibits or
prevents fuel vapor from permeating through the diaphragm 250. The
second layer 254 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 the diaphragm 250. In at least some implementations, the
second layer 254 is trapped between the first layer 252 and either
the main body 16 or first cover 18 (depending upon the orientation
of the diaphragm 250 within the pump). A periphery of the second
layer 254 may instead be embedded within a bead 256 which, in some
implementations, may be formed from the material of the first layer
252 so that the bead is trapped between the first cover 18 and main
body 16 to seal the diaphragm 250 to the first cover and main body.
Alternatively, as shown in FIGS. 17 and 18, the bead 256 can be
formed by the material of both layers 252, 254. Of course, one or
more gaskets may also be used between the diaphragm 250 and the
first cover 18 and/or main body 16, 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.
[0055] 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
in FIGS. 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.
[0056] 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.
* * * * *