U.S. patent application number 11/797211 was filed with the patent office on 2007-11-08 for stepped cylinder piston pump.
Invention is credited to Heiner Ophardt.
Application Number | 20070257064 11/797211 |
Document ID | / |
Family ID | 38565080 |
Filed Date | 2007-11-08 |
United States Patent
Application |
20070257064 |
Kind Code |
A1 |
Ophardt; Heiner |
November 8, 2007 |
Stepped cylinder piston pump
Abstract
A piston pump in which, when the piston is stored or when the
pump is not operative, the piston is received inside a portion of
the chamber with the piston in a position having a larger diameter
than portions of the chamber in which the piston is received when
the piston is operative for pumping.
Inventors: |
Ophardt; Heiner; (Vineland,
CA) |
Correspondence
Address: |
RICHES, MCKENZIE & HERBERT, LLP
SUITE 1800
2 BLOOR STREET EAST
TORONTO
ON
M4W 3J5
CA
|
Family ID: |
38565080 |
Appl. No.: |
11/797211 |
Filed: |
May 1, 2007 |
Current U.S.
Class: |
222/251 |
Current CPC
Class: |
B05B 11/3069 20130101;
F04B 9/14 20130101; B05B 11/3059 20130101; B05B 11/3094 20130101;
B05B 11/3001 20130101 |
Class at
Publication: |
222/251 |
International
Class: |
B65D 88/54 20060101
B65D088/54 |
Foreign Application Data
Date |
Code |
Application Number |
May 5, 2006 |
CA |
2,545,905 |
Claims
1. A pump for dispensing fluid from a reservoir comprising: a
piston-chamber forming member having an inner cylindrical chamber
and an outer cylindrical chamber, the inner chamber and outer
chamber each having a diameter, a chamber wall, an inner end and an
outer end, the diameter of the inner chamber being different than
the diameter of the outer chamber, the inner chamber and outer
chamber being coaxial with the outer end of the inner chamber
opening into the inner end of the outer chamber, the inner chamber
in fluid communication with the reservoir, a piston forming element
received in the piston-chamber forming member axially slidable
inwardly and outwardly therein, a disc on the piston forming
element extending radially outwardly, the piston forming element
slidably received in the piston-chamber forming member for
reciprocal axial inward and outward movement therein in a cycle of
operation between an extended position and a retracted position to
pump fluid from the reservoir out a pump outlet, intermediate
positions between the extended position and the retracted position,
one of the extended position and the retracted position being a set
position, in the set position and between the set position and the
intermediate positions the disc is in the one of the inner chamber
and outer chamber having the larger diameter, in the intermediate
positions, the disc is in the one of the inner chamber and outer
chamber having the smaller diameter, when the disc is in the one of
the inner chamber and outer chamber having the smaller diameter,
the disc engaging the chamber wall thereof circumferentially
thereabout to substantially prevent fluid flow in that chamber past
the disc in at least one of an inward direction and an outward
direction, the pump, after assembly of the piston-chamber forming
member and the piston forming element, being in the set position or
between the set position and the intermediate positions: (a) when
the pump is stored prior to initial use, (b) when the pump is,
after initial use, between cycles of operation, or, (c) when the
pump is stored prior to initial use and when the pump is, after
initial use, between cycles of operation.
2. A pump as claimed in claim 1 wherein the set position is the
extended position.
3. A pump as claimed in claim 1 wherein the set position is the
retracted position.
4. A pump as claimed in claim 1 wherein the diameter of the inner
chamber being lesser than the diameter of the outer chamber.
5. A pump as claimed in claim 1 wherein the diameter of the inner
chamber being greater than the diameter of the outer chamber.
6. A pump as claimed in claim 1 wherein the outer disc has an
inherent diameter when unbiased in a range of 0.1% to 2% greater
than the diameter of the inner chamber and the outer chamber having
the lesser diameter.
7. A pump as claimed in claim 6 wherein the difference in diameters
between the inner chamber and the outer chamber is in the range of
about 0.5% to 1%.
8. A pump as claimed in claim 1 wherein the difference in diameters
between the inner chamber and the outer chamber is not greater than
an amount selected from the group consisting of: 5% of the diameter
of the inner chamber, 2% of the diameter of the inner chamber, 1%
of the diameter of the inner chamber, 0.5% of the diameter of the
inner chamber, 1 mm, 0.1 mm, and 0.05 mm.
9. A pump as claimed in claim 8 wherein when the disc is in the one
of the inner chamber and outer chamber having the larger diameter,
the disc engages the chamber wall thereof circumferentially
thereabout to substantially prevent fluid flow in that chamber past
the disc in at least one of an inward direction and an outward
direction.
10. A pump as claimed in claim 1 wherein the disc having
resiliently deformable edge portion with elastic properties biasing
the edge portion radially outwardly into engagement with the
chamber wall of the one of the inner chamber and outer chamber
having the smaller diameter.
11. A pump as claimed in claim 10 wherein the deformable edge
portion is formed from material which is subject to a reduction of
its elastic properties biasing the edge portion radially outwardly
when: (a) the edge portion is held in the set position for a period
of time or (b) the edge portion is held in the set position for a
period of time at temperatures above 30 degrees Celsius.
12. A pump as claimed in claim 11 wherein the deformable edge
portion is formed from plastic material.
13. A pump as claimed in claim 12 wherein the deformable edge
portion is formed from plastic material selected from polyethylene
and polypropylene.
14. A pump as claimed in claim 1 wherein said piston forming
element having an axially extending hollow stem having a central
passageway having an outlet proximate an outer end and an inlet
located on the stem between the inner disc and the outer disc, the
disc comprising an outer disc on the stem substantially preventing
fluid flow in the inner chamber past the outer disc in an outward
direction, an inner disc on the stem spaced axially inwardly from
the outer disc extending radially outwardly from the stem to
proximate the chamber wall of the inner chamber circumferentially
thereabout, the inner disc substantially preventing fluid flow in
the inner chamber past the inner disc in an inward direction, the
inner disc elastically deforming away from the chamber wall of the
inner chamber to permit fluid flow in the inner chamber past the
inner disc in an outward direction.
15. A pump as claimed in claim 14 wherein the outer disc
substantially preventing fluid flow in the inner chamber past the
outer disc in an inward direction.
16. A pump as claimed in claim 1 wherein said piston forming
element having an axially extending hollow stem having a central
passageway having an outlet proximate an outer end and an inlet
located on the stem between the inner disc and the outer disc, the
disc comprising an inner disc on the stem, an outer disc on the
stem spaced axially outwardly from the inner disc extending
radially outwardly from the stem to proximate the chamber wall of
the outer chamber circumferentially thereabout, the outer disc
substantially preventing fluid flow in the outer chamber past the
inner disc in an inward direction, the outer disc elastically
deforming away from the chamber wall of the outer chamber to permit
fluid flow in the outer chamber past the outer disc in an outward
direction.
17. A pump for dispensing fluid from a reservoir comprising: a
piston-chamber forming member having an inner cylindrical chamber,
an intermediate chamber and an outer cylindrical chamber, the inner
chamber, intermediate chamber and outer chamber each having a
diameter, a chamber wall, an inner end and an outer end, the
diameter of the inner chamber being less than the diameter of the
intermediate chamber, the diameter of the intermediate chamber
being less than the diameter of the outer chamber, the inner
chamber, intermediate chamber and outer chamber being coaxial with
the outer end of the inner chamber opening into the inner end of
the intermediate chamber and with the outer end of the intermediate
chamber opening into the inner end of the outer chamber, the inner
chamber in fluid communication with the reservoir, a piston forming
element received in the piston-chamber forming member axially
slidable inwardly and outwardly therein, an inner disc on the
piston forming element extending radially outwardly, an outer disc
on the piston forming element extending radially outwardly, the
outer disc located on the piston axially outwardly from the inner
disc, the piston forming element slidably received in the
piston-chamber forming member for reciprocal axial inward and
outward movement therein in a cycle of operation between an
extended position and a retracted position to pump fluid from the
reservoir out a pump outlet, intermediate positions between the
extended position and the retracted position, in the retracted
position and between the retracted position and the intermediate
positions the inner disc is in the inner chamber and the outer disc
is in the intermediate chamber, in the extended position and
between the extended position and the intermediate positions the
inner disc is in the intermediate chamber and the outer disc is in
the outer chamber, when the inner disc is in the inner chamber, the
inner disc engaging the chamber wall thereof circumferentially
thereabout to substantially prevent fluid flow in the inner chamber
past the inner disc in at least one of an inward direction and an
outward direction, when the outer disc is in intermediate chamber,
the outer disc engaging the chamber wall thereof circumferentially
thereabout to substantially prevent fluid flow in the intermediate
chamber past the outer disc in at least one of an inward direction
and an outward direction, the pump, after assembly of the
piston-chamber forming member and the piston forming element, being
in the extended position or between the extended position and the
intermediate positions: (a) when the pump is stored prior to
initial use, (b) when the pump is, after initial use, between
cycles of operation, or, (c) when the pump is stored prior to
initial use and when the pump is, after initial use, between cycles
of operation.
18. A pump as claimed in claim 17 wherein said piston forming
element having an axially extending hollow stem having a central
passageway having an outlet proximate an outer end and an inlet
located on the stem between the inner disc and the outer disc, the
inner disc provided on the stem extending radially outwardly from
the stem, the outer disc on the stem spaced axially outwardly from
the inner disc and extending radially outwardly from the stem, the
inner disc when in the inner chamber substantially preventing fluid
flow in the inner chamber past the inner disc in an inward
direction, the outer disc when in the intermediate chamber
substantially preventing fluid flow in the intermediate chamber
past the outer disc in an outward direction.
19. A pump as claimed in claim 18 including a one-way valve between
the reservoir and the inner chamber preventing fluid flow inwardly
from the inner chamber to the reservoir.
20. A pump for dispensing fluid from a reservoir comprising: a
piston-chamber forming member having an inner cylindrical chamber,
an intermediate chamber and an outer cylindrical chamber, the inner
chamber, intermediate chamber and outer chamber each having a
diameter, a chamber wall, an inner end and an outer end, the
diameter of the intermediate chamber being greater than the
diameter of the inner chamber, the diameter of the intermediate
chamber being greater than the diameter of the outer chamber, the
inner chamber, intermediate chamber and outer chamber being coaxial
with the outer end of the inner chamber opening into the inner end
of the intermediate chamber and with the outer end of the
intermediate chamber opening into the inner end of the outer
chamber, the inner chamber in fluid communication with the
reservoir, a piston forming element received in the piston-chamber
forming member axially slidable inwardly and outwardly therein, a
disc on the piston forming element extending radially outwardly,
the piston forming element slidably received in the piston-chamber
forming member for reciprocal axial inward and outward movement
therein in a cycle of operation between an extended position and a
retracted position to pump fluid from the reservoir out a pump
outlet, when the disc is in the intermediate chamber, the disc
engaging the chamber wall thereof circumferentially thereabout to
substantially prevent fluid flow in the intermediate chamber past
the disc in at least one of an inward direction and an outward
direction, in the retracted position, the disc is in the inner
chamber, in the extended position, the disc is in the outer
chamber, the pump, after assembly of the piston-chamber forming
member and the piston forming element, being in a position that the
disc is in the inner chamber or in the outer chamber: (a) when the
pump is stored prior to initial use, (b) when the pump is, after
initial use, between cycles of operation, or (c) when the pump is
stored prior to initial use and when the pump is, after initial
use, between cycles of operation, when the disc is in the one of
the inner chamber or outer chamber, the disc engages the chamber
wall thereof circumferentially thereabout to substantially prevent
fluid flow in that chamber past the disc in at least one of an
inward direction and an outward direction.
Description
SCOPE OF THE INVENTION
[0001] This invention relates to piston pumps and, more
particularly, to a stepped piston pump with a stepped cylinder to
accommodate piston shrinkage or setting.
BACKGROUND OF THE INVENTION
[0002] Piston pumps are well known in which a piston reciprocally
slides within a chamber. For many piston pumps, the piston includes
an annular disc with an inherent resiliency biasing a periphery of
the disc into engagement with an inner wall of the chamber to form
a seal therewith. Frequently such discs may permit fluid flow in
one direction therepast by a pressure differential across the disc
urging the disc against its bias away from sealed engagement with
the inner wall of the chamber and with the inherent bias of the
disc causing the disc to assume a sealed position.
[0003] The present inventor has appreciated that under various
conditions, the inherent resiliency of the disc may become impaired
such that the disc will not adequately perform its function and the
pump may have its performance reduced or fail. For example, the
present inventor has appreciated that with pistons incorporating
resilient discs which are made of plastic material, that the disc
can be subject to setting and shrinkage. Setting arises, for
example, when a disc is received in a chamber which disc has an
initial inherent bias to assume a diameter larger than the diameter
of the inner wall of the chamber such that the disc's inherent bias
urges the disc into engagement with the inner wall of the chamber.
That is, the disc is compressed inside the chamber. If, however,
such disc may be left in such compressed condition in the chamber
for an extended period of time, then the disc may loose its
inherent resiliency as, for example, tending to set and retain the
shape in which it is held for an extended period of time and losing
its bias to expand further outwardly. The extent to which setting
or set may arise will determine the extent to which the disc member
forms a functional seal with the inner wall of the chamber. Set is
increased with the time during which the disc is retained in one
position. Set with most plastic materials increases with increased
temperature. For example, with many relatively inexpensive plastic
materials as may preferably be used to form pistons for pumps,
leaving a disc of a piston in a fixed condition within a cylinder
for a number of days at temperatures in excess of 35.degree. C. and
higher can significantly increase the extent to which a set is
developed. Nevertheless, where the assembled pumps are left, for
example, in storage in many climatic conditions, it may not be
unrealistic for the pumps to be subjected for temperatures in the
range of 35.degree. C. to 60.degree. C. for hours if not days as in
transit, storage and the like.
[0004] The present inventor has also appreciated that set and the
reduced inherent resiliency of a disc may arise when the disc may
be subjected to certain fluids to be dispensed by the pump
including chemicals which negatively affect the properties of the
plastic with the time that they are left in a particular
position.
[0005] The present inventor has also appreciated that there are
plastic materials which may be preferred for use with pistons in
pumps which can be subject to shrinkage when exposed to increased
temperatures for periods of time. Thus, many plastic discs in
piston pumps will also be subject to shrinkage when exposed to
temperatures above, say, 35.degree. C. for an extended period of
time which shrinkage can be enhanced and rendered more permanent as
when a disc is retained in a compressed condition within the
cylinder during the time that it is subjected to the elevated
temperatures.
SUMMARY OF THE INVENTION
[0006] To at least partially overcome these disadvantages of
previously known devices, the present invention provides a piston
pump in which, when the piston is stored or when the pump is not
operative, the piston is received inside a portion of the chamber
with the piston in a position having a larger diameter than
portions of the chamber in which the piston is received when the
piston is operative for pumping.
[0007] An object of the present invention is to provide an improved
piston pump assembly to overcome difficulties which may arise due
to setting, the loss of resiliency or shrinkage of a piston-forming
member.
[0008] Another object is to provide a piston pump which provides
for useful operation of the pump even after a piston sealing member
may have shrunk or become set to adopt an effectively smaller
diameter.
[0009] A pump in accordance with the present invention has a piston
reciprocally axially slidable within a chamber, with the piston
assuming an axial set position within the chamber when the piston
is not in use or when it is stored as after initial assembly. While
the piston is in such set position, the piston is received within a
set portion of the chamber having a larger circumference than other
portions of the chamber into which the piston will slide when moved
for pumping. The piston may, due to engagement in the larger
diameter set portion of the chamber, become set to assume the
diameter of the larger diameter set portion of the chamber or may
shrink as to assume the diameter of the larger diameter set portion
of the chamber which may impair the engagement of the piston in the
larger diameter set portion. However, on movement of the piston in
use into the other portions of the chamber having smaller
diameters, the effects of set or shrinkage of the piston on
engagement with the chamber will be reduced. Preferably, when the
piston is in the set portion of the chamber, even after reasonably
expected setting or shrinkage, the piston will continue to engage
the wall of the chamber. It is within the scope of the invention,
however, that when the piston is in the set position that the disc
not engage the wall of the chamber. Pumps in accordance with the
present invention provide a stepped chamber with a larger diameter
set portion of the chamber to be a portion or portions in which the
piston is received when not operative and/or is being in storage
preferably with the set position or positions being a fully
retracted position or a fully withdrawn position. Preferably, the
difference between the diameter of the larger diameter set portion
and the other portion of the chamber is selected to be as small as
possible to reasonably accommodate expected set or shrinkage.
[0010] Piston pumps may have pistons with more than one disc to
engage the inner walls of a piston chamber and a separate stepped
arrangement may be provided for each disc although this may not be
necessary and merely to provide a stepped configuration for one of
the discs may be adequate to ensure reasonable operation of the
pump.
[0011] The present invention provides by use of a stepped chamber a
mechanism for accommodating adequate function of the pump
notwithstanding set or shrinkage and, as well, permits the piston
for the pump to be made from more easily handled and less expensive
materials as, for example, plastics having lower melting and
increased likelihood of set and shrinkage.
[0012] The invention is for use not only with pistons which have
discs which extend radially outwardly to engage an inner wall of
the chamber but also with arrangements in which a chamber may have
a annular disc which extends radially inwardly as to engage a
cylindrical surface on a piston. In the latter case, the diameter
of the piston to be engaged by the radially outwardly extending
disc should be reduced when the piston is in a set position it
assumes when not in use.
[0013] In one aspect, the present invention provides a pump for
dispensing fluid from a reservoir comprising:
[0014] a piston-chamber forming member having an inner cylindrical
chamber and an outer cylindrical chamber, the inner chamber and
outer chamber each having a diameter, a chamber wall, an inner end
and an outer end,
[0015] the diameter of the inner chamber being different than the
diameter of the outer chamber,
[0016] the inner chamber and outer chamber being coaxial with the
outer end of the inner chamber opening into the inner end of the
outer chamber,
[0017] the inner chamber in fluid communication with the
reservoir,
[0018] a piston forming element received in the piston-chamber
forming member axially slidable inwardly and outwardly therein,
[0019] a disc on the piston forming element extending radially
outwardly,
[0020] the piston forming element slidably received in the
piston-chamber forming member for reciprocal axial inward and
outward movement therein in a cycle of operation between an
extended position and a retracted position to pump fluid from the
reservoir out a pump outlet,
[0021] intermediate positions between the extended position and the
retracted position,
[0022] one of the extended position and the retracted position
being a set position,
[0023] in the set position and between the set position and the
intermediate positions, the disc is in the one of the inner chamber
and outer chamber having the larger diameter,
[0024] when the disc is in the one of the inner chamber and outer
chamber having the smaller diameter, the disc engaging the chamber
wall thereof circumferentially thereabout to substantially prevent
fluid flow in that chamber past the disc in at least one of an
inward direction and an outward direction,
[0025] the pump, after assembly of the piston-chamber forming
member and the piston forming element, being in the set position or
between the set position and the intermediate positions: (a) when
the pump is stored prior to initial use, (b) when the pump is,
after initial use, between cycles of operation, or, (c) when the
pump is stored prior to initial use and when the pump is, after
initial use, between cycles of operation.
[0026] In another aspect, the present invention provides a pump for
dispensing fluid from a reservoir comprising:
[0027] a piston-chamber forming member having an inner cylindrical
chamber, an intermediate chamber and an outer cylindrical chamber,
the inner chamber, intermediate chamber and outer chamber each
having a diameter, a chamber wall, an inner end and an outer
end,
[0028] the diameter of the inner chamber being less than the
diameter of the intermediate chamber,
[0029] the diameter of the intermediate chamber being less than the
diameter of the outer chamber,
[0030] the inner chamber, intermediate chamber and outer chamber
being coaxial with the outer end of the inner chamber opening into
the inner end of the intermediate chamber and with the outer end of
the intermediate chamber opening into the inner end of the outer
chamber,
[0031] the inner chamber in fluid communication with the
reservoir,
[0032] a piston forming element received in the piston-chamber
forming member axially slidable inwardly and outwardly therein,
[0033] an inner disc on the piston forming element extending
radially outwardly,
[0034] an outer disc on the piston forming element extending
radially outwardly,
[0035] the outer disc located on the piston forming element axially
outwardly from the inner disc,
[0036] the piston forming element slidably received in the
piston-chamber forming member for reciprocal axial inward and
outward movement therein in a cycle of operation between an
extended position and a retracted position to pump fluid from the
reservoir out a pump outlet,
[0037] intermediate positions between the extended position and the
retracted positions,
[0038] in the retracted position and between the retracted position
and the intermediate positions, the inner disc is in the inner
chamber and the outer disc is in the intermediate chamber,
[0039] in the extended position and between the extended position
and the intermediate position, the inner disc is in the
intermediate chamber and the outer disc is in the outer
chamber,
[0040] when the inner disc is in inner chamber, the inner disc
engaging the chamber wall thereof circumferentially thereabout to
substantially prevent fluid flow in the inner chamber past the
inner disc in at least one of an inward direction and an outward
direction,
[0041] when the outer disc is in intermediate chamber, the outer
disc engaging the chamber wall thereof circumferentially thereabout
to substantially prevent fluid flow in the intermediate chamber
past the outer disc in at least one of an inward direction and an
outward direction,
[0042] the pump, after assembly of the piston-chamber forming
member and the piston forming element, being in the extended
position or between the extended position and the intermediate
positions: (a) when the pump is stored prior to initial use, (b)
when the pump is, after initial use, between cycles of operation,
or, (c) when the pump is stored prior to initial use and when the
pump is, after initial use, between cycles of operation.
[0043] In another aspect, the present invention provides a pump for
dispensing fluid from a reservoir comprising:
[0044] a piston-chamber forming member having an inner cylindrical
chamber, an intermediate chamber and an outer cylindrical chamber,
the inner chamber, intermediate chamber and outer chamber each
having a diameter, a chamber wall, an inner end and an outer
end,
[0045] the diameter of the intermediate chamber being greater than
the diameter of the inner chamber,
[0046] the diameter of the intermediate chamber being greater than
the diameter of the outer chamber,
[0047] the inner chamber, intermediate chamber and outer chamber
being coaxial with the outer end of the inner chamber opening into
the inner end of the intermediate chamber and with the outer end of
the intermediate chamber opening into the inner end of the outer
chamber,
[0048] the inner chamber in fluid communication with the
reservoir,
[0049] a piston forming element received in the piston-chamber
forming member axially slidable inwardly and outwardly therein,
[0050] a disc on the piston forming element extending radially
outwardly,
[0051] the piston forming element slidably received in the
piston-chamber forming member for reciprocal axial inward and
outward movement therein in a cycle of operation between an
extended position and a retracted position to pump fluid from the
reservoir out a pump outlet,
[0052] when the disc is in the intermediate chamber, the disc
engaging the chamber wall thereof circumferentially thereabout to
substantially prevent fluid flow in the intermediate chamber past
the disc in at least one of an inward direction and an outward
direction,
[0053] in the retracted position the disc is in the inner,
[0054] in the extended position the disc is in the outer
chamber,
[0055] the pump, after assembly of the piston-chamber forming
member and the piston forming element, being in a position that the
disc is in the inner chamber or in the outer chamber: (a) when the
pump is stored prior to initial use, (b) when the pump is, after
initial use, between cycles of operation, or (c) when the pump is
stored prior to initial use and when the pump is, after initial
use, between cycles of operation,
[0056] when the disc is in the one of the inner chamber or outer
chamber, the disc engages the chamber wall thereof
circumferentially thereabout to substantially prevent fluid flow in
that chamber past the disc in at least one of an inward direction
and an outward direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] Further aspects and advantages of the present invention will
become apparent from the following description taken together with
the accompanying drawings in which:
[0058] FIG. 1 is a schematic cross-sectional side view of a piston
pump in accordance with a first embodiment of the present invention
in an extended position;
[0059] FIG. 2 is a view the same as in FIG. 1, however, with the
piston in an intermediate position;
[0060] FIG. 3 is a view the same as in FIG. 1, however, with the
piston in a retracted position;
[0061] FIG. 4 is a schematic cross-sectional side view of a piston
pump in accordance with a second embodiment of the present
invention in an extended position;
[0062] FIG. 5 is a view the same as in FIG. 4, however, with the
piston in an intermediate position;
[0063] FIG. 6 is a view the same as in FIG. 4, however, with the
piston in a retracted position;
[0064] FIG. 7 is a schematic cross-sectional side view of a piston
pump in accordance with a third embodiment of the present invention
in a retracted position;
[0065] FIG. 8 is a schematic cross-sectional side view of a piston
pump in accordance with a fourth embodiment of the present
invention in a retracted position;
[0066] FIG. 9 is a schematic cross-sectional side view of a piston
pump in accordance with a fifth embodiment of the present invention
in a retracted position;
[0067] FIG. 10 is a schematic cross-sectional side view of a piston
pump in accordance with a sixth embodiment of the present invention
in an retracted position;
[0068] FIG. 11 is a view the same as in FIG. 10, however, with the
piston in an inner intermediate position;
[0069] FIG. 12 is a view the same as in FIG. 10, however, with the
piston in an outer intermediate position; and
[0070] FIG. 13 is a view the same as in FIG. 10, however, with the
piston in an extended position.
DETAILED DESCRIPTION OF THE DRAWINGS
[0071] Reference is made to FIGS. 1 to 3 which show a liquid
dispenser 10 having a pump assembly 12 attached to a reservoir 13
in accordance with the present invention.
[0072] The reservoir 13 is a container with a threaded neck 14. The
pump assembly 12 has a piston chamber-forming body 16 defining a
chamber 18 therein in which a piston forming element or piston 20
is slidably disposed for reciprocal movement to dispense fluid from
the reservoir. The chamber 18 is defined inside side walls 42 of an
inner tube 26. The chamber 18 is closed at an inner end wall 23 and
open at an outer end 24. Openings 22 in the end wall 23 of the
chamber 18 are in communication with the fluid in the reservoir 13.
A one-way valve 25 across the opening 22 permits fluid flow
outwardly from the reservoir 13 into the chamber 18 but prevents
fluid flow inwardly.
[0073] The piston chamber-forming body 16 has the cylindrical inner
tube 26 defining the chamber 18 therein. An outer tubular member 28
is provided radially outwardly of the inner tube 26 joined by a
radially extending shoulder 27 to the inner tube 26. The outer
tubular member 28 carries threads 29 thereon which engages the
threaded neck 14 of the reservoir 13 to form a fluid impermeable
seal therewith.
[0074] Fluid from the reservoir 13 is in communication with the
piston chamber 18 via the opening 22.
[0075] The one-way valve 25 has a shouldered button 30 which is
secured in a snap-fit inside a central opening in the end wall 23
of the chamber 18. A flexible annular rim 31 is carried by the
button 30 and extends radially outwardly to the side wall 42 of the
inner tube 26. When the pressure in the chamber 18 is less than
that in reservoir 13, the rim 31 is deflected away from the walls
of the inner tube 26 and fluid may flow from the reservoir 13
through exit openings 22 and past the rim 31 into the chamber 18.
Fluid flow in the opposite direction is blocked by rim 31, which is
biased radially outwardly into the side wall 42 of the inner tube
26.
[0076] The piston-forming element or piston 20 is preferably a
unitary element formed of plastic. The piston 20 has a hollow stem
32.
[0077] Two circular inner and outer discs 33 and 34 are located on
the stem 32 spaced from each other. The inner disc 33 resiliently
engages the side wall of the chamber 18 to permit fluid flow
outwardly therepast by resilient deflection away from the side wall
when the pressure in the chamber 18 inward of the disc 33 is
greater than the pressure outward of the disc 33. Inner disc 33
prevents fluid flow inwardly therepast. Thus, the inner disc 33
functions as a second one-way valve. The outer disc 34 engages the
side wall of the chamber 18 to prevent fluid flow outwardly
therepast.
[0078] The piston stem 32 has a hollow passageway 35 extending
along the axis 40 of the piston 20 from a blind inner end 38 to an
outlet 36 at an outer end. Inlets 37 to the passageway 35 are
provided on the stem 32 between the inner disc 33 and outer disc
34. By reciprocal movement of the piston 20 in the chamber 18,
fluid is drawn from reservoir 13 through exit openings 22 past the
inner disc 33 and via the inlets 37 into the passageway 35 and
along the passageway 35 to exit the outlet 36.
[0079] The piston chamber-forming body 16 is preferably injection
moulded as a unitary element. The one-way valve 24 and the piston
forming element 20 are separate elements.
[0080] In FIGS. 1 to 3, the piston 20 is reciprocally movable in a
single stroke of operation from an extended position as shown in
FIG. 1 to the retracted position shown in FIG. 3 and then back to
the extended position of FIG. 1. In moving between the extended
position of FIG. 1 and the retracted position of FIG. 3, the piston
moves through the intermediate position shown in FIG. 2.
[0081] In accordance with the first embodiment illustrated in FIGS.
1 to 3, the piston 20 is, after each stroke of operation, to be
retained in the extended position until next activated. In this
regard, in accordance with the first embodiment, a spring member
(not shown) biases the piston 20 to the extended position with a
stop mechanism (not shown) preventing further outward movement of
the piston than the extended position of FIG. 1. Such spring biased
soap dispensers are well known in which a user will move the piston
from the extended position to the retracted position against the
bias of a spring and the spring will return the piston to a fixed
extended position in which position the piston will remain until
next activation by a user.
[0082] As seen in FIGS. 1 to 3, the side wall 42 of the chamber has
three portions, an inner chamber portion 44 of a constant diameter,
an outer chamber portion 48 of a constant diameter greater than the
diameter of the inner portion and a transition portion 46 which
decreases in diameter outwardly from the inner portion 44 to the
outer portion 48. As seen, a first transition line 45 is disposed
between the inner chamber portion 44 and a transition portion 46.
Another transition line 47 is disposed between the transition
chamber portion 46 and the outer chamber portion 48.
[0083] In the extended position as shown in FIG. 1, the outer disc
34 is received in the outer chamber portion 48 and the inner disc
33 is in the inner chamber portion 44. In moving the piston
inwardly from the extended position shown in FIG. 1, the outer disc
passes through the transition portion into the intermediate
position illustrated in FIG. 2 in which the outer disc 34 is first
received within the inner chamber portion 44. In moving between the
intermediate position shown in FIG. 2 and the retracted position in
FIG. 3, the outer disc 34 is maintained within the inner chamber
portion 44. A pump may be left in the extended position shown in
FIG. 1 for long periods of time and under elevated temperature
conditions. In the extended position as seen in FIG. 1, the outer
disc 34 preferably, at least when initially constructed, has an
inherent bias such that the peripheral edges of the disc 34 are,
due to the inherent bias of the disc, urged outwardly into the
inner wall of the outer chamber portion 48. With the passage of
time, the outer disc 34 may become subject to set or shrinkage such
that it loses its resiliency and is biased outwardly with reduced
force. Notwithstanding any setting or shrinkage of the outer disc
34, on movement of the outer disc 34 to the intermediate position
of FIG. 2, the outer disc 34 becomes received within the inner
chamber portion 44 having a reduced diameter increasing the extent
to which the outer disc 34 engages the inner wall of the chamber,
thus providing for improved pumping as contrasted with a pump in
which the entirety of the chamber had the diameter of the outer
chamber portion 48.
[0084] Reference is made to FIGS. 4 to 6 which illustrate a pump
assembly similar to that in FIGS. 1 to 3 and which the same
reference numerals are used to refer to the same elements. One
difference in the second embodiment in FIGS. 4 to 6 is that the
inner wall 42 of the chamber 18 has five portions, an inner chamber
portion 50, an inner transition chamber portion 52, an intermediate
chamber portion 54, an outer transition chamber portion 56 and an
outer chamber portion 58. Each of the inner chamber portion 50,
intermediate chamber portion 54 and outer chamber portion 58 have a
constant diameter, however, with the diameter of the inner chamber
portion 50 being less than the diameter of the intermediate chamber
portion 54 and the diameter of the intermediate chamber portion 54
being less than the diameter of the outer chamber portion 58. In
the embodiment of FIGS. 4 to 5, the pump is to remain in the
extended position of FIG. 4 when not in use and is to be moved in a
cycle of operation from the extended position of FIG. 4 through the
intermediate position of FIG. 5 to the retracted position of FIG. 6
then back through the intermediate position of FIG. 5 to the
extended position of FIG. 4. In the extended position, the outer
disc 34 is in the outer chamber portion 58 and the inner disc 33 is
in the intermediate chamber portion 54. From this position, the
piston is initially moved inwardly to the intermediate position of
FIG. 5 in which the outer piston 34 is in the intermediate chamber
portion 54 and the inner disc 33 is in the inner chamber portion
50. In sliding between the intermediate position of FIG. 5 and the
retracted position of FIG. 6, the outer disc 34 continues to remain
in the constant diameter intermediate chamber portion 54 and the
inner disc 33 remains in the constant diameter inner chamber
portion 50.
[0085] With the embodiments of FIGS. 4 to 6, both the outer disc 34
and the inner disc 33, are in the extended position, in which they
may remain when not in use in a larger diameter portion of the
chamber than in a portion immediately inwardly therefrom in which
they are substantially constantly retained during use of the pump
in pumping. Thus, shrinkage or set by either of the outer disc 34
or the inner disc 33 is, to some extent, accommodated without
performance reduction.
[0086] FIG. 7 illustrates a third embodiment of a piston pump in
accordance with the present invention in which the same reference
numerals are used to refer to the same elements as in FIG. 1. In
the embodiment of FIG. 7, however, the pump is intended to be
maintained in the retracted position, shown in FIG. 7, when not in
use. In use, the piston 20 is to be moved from the retracted
position to an extended position. In the retracted position, the
outer disc 34 is received in an enlarged diameter inner chamber
portion 44. With outward movement of the piston, the outer disc 34
moves over a transition chamber portion 46 to an intermediate
position in which the outer disc 34 first enters the outer chamber
portion 48 of reduced diameter. In reciprocal use of the pump,
advantageous pumping occurs in sliding between an intermediate
position and a fully extended position or in between such positions
during which the outer disc 34 is maintained in the outer chamber
portion and the inner disc 33 is maintained in the constant
diameter inner chamber portion 44.
[0087] Reference is now made to FIG. 8 which illustrates a fourth
embodiment in which in a manner analogous to that described with
reference to FIGS. 4 to 6, but as in the embodiment in FIG. 7, the
piston is to be retained in a retracted position when not in use.
In FIG. 8, there are five portions in the chamber, namely, an inner
chamber portion 50, an inner transition chamber portion 52, an
intermediate chamber portion 54, an outer transition chamber
portion 56 and an outer chamber portion 58 of the chamber with the
inner chamber portion 50, intermediate chamber portion 54, outer
chamber portion 58 having substantially constant but different
diameters and with the diameter of the inner chamber portion 50
being greater than the diameter of the intermediate chamber portion
54 which is greater than the diameter of the outer chamber portion
58. In a fully retracted position as seen in FIG. 8 in which the
piston pump assumes at rest, each of the outer disc 34 and the
inner disc 33 are received in an enlarged diameter chamber portions
compared to the diameter of the chamber portions in which the discs
are to slide in operation of the pump from an intermediate position
to an extended position.
[0088] The pump assembly in each of FIGS. 1 to 8 includes the
one-way valve 25 and a piston 20 with two discs 33 and 34. FIG. 9
illustrates a pump assembly which avoids use of a separate one-way
valve and the piston 20 carries three discs to provide, in effect,
two one-way valves.
[0089] Referring to FIG. 9, the piston has three discs, namely, an
outer disc 34, an intermediate disc 33 and an inner disc 70. The
pump shown is intended to be maintained in the extended position
shown in FIG. 9 when not in use. The outer disc 34 in the extended
position is received in an enlarged diameter outermost chamber
portion 58 such that on movement of the piston inwardly for
pumping, the outer disc 34 comes to be engaged within the smaller
diameter intermediate chamber portion 54. The intermediate disc 33
is always received in the constant diameter intermediate chamber
portion 54. The inner disc 70 is always received in the constant
diameter inner chamber portion 50. A step shoulder 52 is between
inner chamber portion 50 and intermediate chamber portion 54. A
transition chamber portion 56 is between intermediate chamber
portion 54 and outer chamber portion 58.
[0090] Reference is made to FIG. 10 which illustrates a sixth
embodiment in accordance with the present invention. As seen in
FIG. 10, the inner tube 26 is shown to have an inner chamber
portion 50 of a first constant diameter, an inner transition
chamber portion 52, an intermediate chamber portion 54 of a
constant diameter, an outer transition chamber portion 56 and an
outer chamber wall portion 58 of constant diameter. The inner
transition chamber portion 52 bridges between the inner chamber
portion 50 and the intermediate chamber portion 54, and has a
diameter less than the diameter of the intermediate chamber portion
54. The outer chamber portion 58 has a diameter less than the
intermediate chamber portion 54. The pump is shown in four
positions, a fully retracted position as illustrated in FIG. 10, an
inner intermediate position as shown in FIG. 11, an outer
intermediate position as shown in FIG. 12 and a fully extended
position as shown in FIG. 13. The pump of FIGS. 10 to 13 is
intended to be stored and shipped in the fully retracted position
as illustrated in FIG. 10, for example, as (a) merely assembled and
not coupled to a bottle reservoir or (b) assembled and coupled to a
bottle but not engaged on a dispenser. In the fully retracted
position, the outer disc 34 is received within the reduced diameter
inner transition chamber portion 52. U.S. Pat. No. 5,975,360 issued
Nov. 2, 1999 to Ophardt discloses in FIG. 8 a piston pump which is
assembled and coupled to a bottle in a retracted position but
which, when coupled to a dispenser as shown in FIG. 8 of that
patent, is at rest in an extended position.
[0091] The pump, after being stored in the retracted position of
FIG. 10, may then be coupled to a dispenser which dispenser firstly
holds the pump in a rest position between strokes in the extended
position of FIG. 13 and in use moves the piston inwardly and
outwardly between the fully extended position of FIG. 13 and the
inner intermediate position of FIG. 11. Thus, the operation of the
pump is preferably selected such that after being placed in a
dispenser, the piston 20 is not moved inwardly past the inner
intermediate position of FIG. 11 and, hence, is not again moved to
the storage, retracted position of FIG. 10. In the operative
stroking of the pump in use, the piston 20 is moved between the
extended position of FIG. 13 and the inner intermediate position of
FIG. 11. The pump is intended to be held when not in use in the
extended position of FIG. 13 in which the outer disc 34 is engaged
in the enlarged diameter outer chamber portion 58. In operation,
the inner disc 34 substantially only engages and moves along the
constant diameter inner chamber portion 50 in all movement between
the retracted position and the extended position. The inner chamber
portion 50 is shown to have a diameter the same as the intermediate
chamber portion 54, however, it may have a diameter which is
greater or lesser than the intermediate chamber portion 54 with the
inner transition chamber portion 52 suitably modified.
[0092] This embodiment of FIG. 10 has the advantage that when the
pump may be stored prior to use as, for example, in the stored
retracted position of FIG. 10, the outer piston 34 is in the
enlarged diameter inner chamber portion 50 of the chamber and, as
well, when incorporated into a dispenser for use, when not in use,
the outer disc 34 is in another enlarged diameter outer chamber
portion 58 of the chamber.
[0093] In accordance with the present invention, pump arrangements
are preferred wherein the position of the piston when stored or
assembled, whether or not coupled to a bottle reservoir and whether
or not coupled to a dispenser, is the same as the position of the
piston when at rest in between cycles of operation. Storage of the
piston can include storage as when a piston pump is assembled but
before it may be coupled to a bottle reservoir and after the pump
assembly may be coupled to a bottle reservoir before the pump and
reservoir as a sub assembly may become coupled to a dispenser.
Storage can also include a condition of being coupled to a
dispenser ready for use.
[0094] While not necessary, it is preferred in accordance with the
present invention that the piston disc when in a larger diameter
portion of a chamber continues to provide some seal and engagement
between the outer disc and the inner wall of the chamber. In this
regard, it is preferred that the difference in diameter, for
example, in the context of FIG. 1, between the inner chamber
portion 44 and the outer chamber portion 48 is selected to be not
greater than a difference required to accommodate for expected set
and/or shrinkage. Minimizing this difference in diameter can be
advantageous at least in reducing the extent to which the
transitional chamber portion 46 may be required and providing for
smooth sliding of the piston when subjected to relatively constant
axial forces. Preferably, this difference in diameter is not
greater than an amount selected from the group consisting of: 5% of
the diameter of the inner chamber portion; 2% of the diameter of
the inner chamber portion; 1% of the diameter of the inner chamber
portion and 0.5% of the diameter of the inner chamber portion and
0.2% of the diameter of the inner chamber portion.
[0095] The inner and outer discs 33 and 34 illustrated in the
preferred embodiments preferably have resiliently deformable edge
portions with elastic properties biasing the edge portion radially
outwardly into engagement with the chamber wall. Such deformable
edge portion may be formed from plastic material which is subject
to reduction of its elastic properties biasing the edge portion
radially outwardly when the edge portion is held in a set position
for a period of time or when the edge portion is held in the set
position for a period of time at temperatures above 35.degree. C.
or 40.degree. C. or 50.degree. C. or 60.degree. C. In accordance
with preferred embodiments of the present invention, the piston
element is made from a plastic material preferably injection
moulded as an unitary element from plastic material and, thus, the
deformable edge portion is preferably formed from a plastic
material.
[0096] In accordance with the present invention, the deformable
edge portion may be formed from relatively inexpensive plastics
including polyethylene, low density polyethylene and polypropylene
so as to advantageously reduce the costs of materials.
[0097] Having regard to typical such plastics which may be used for
construction of the piston, when the discs on the piston may have a
diameter in the range of 5 to 40 mm, it is preferred that the
difference in diameter between the inner chamber portion and the
outer chamber portion be in the range of about 0.25% and 2%, more
preferably, about 0.5% to about 1% with the disc having an inherent
unbiased diameter of about 0.5% to 4% greater than the diameter of
the inner chamber portion, more preferably, about 1% to 2% greater
than the diameter of the inner chamber portion. In the embodiment
of FIG. 1, each of the inner disc 33 and outer disc 34 most
preferably has an inherent diameter when unbiased or compressed of
about 1.5% greater than the diameter of the inner chamber portion
44; and the outer chamber portion 48 preferably has a diameter of
about one half the sum of the inherent diameter of the disc 34 and
the diameter of the inner chamber portion 44. In one preferred
embodiment utilizing a low density polyethylene plastic material,
the diameter of the inner chamber portion 44 is about 12.15 mm, the
diameter of the outer chamber portion 46 is about 12.25 mm and the
inherent diameter of the outer disc 34 is about 12.33 mm.
[0098] Embodiments as illustrated in FIGS. 7, 8 and 10 have at
least one chamber portion of a smaller diameter inward of a chamber
portion of larger diameter. However, preferably, the piston-chamber
forming member 16 is formed by injection moulding as a unitary
element. Due to the inherent resiliency of the plastic of the
piston-chamber forming member 16 during injection moulding, a
centrally extending core may be provided with an enlarged portion
to form the undercut, smaller diameter inward chamber portion. The
relative difference between the diameter of the inner chamber
portion and outer chamber portion is preferably limited to be no
more than about 2%, more preferably, 1% or 0.5% to assist in
permitting manufacture with such a removable core.
[0099] While the invention has been described with reference to the
preferred embodiments many variations and modifications will now
occur to persons skilled in the art. For a definition of the
invention reference is made to the following claims.
* * * * *