U.S. patent application number 16/460729 was filed with the patent office on 2020-01-09 for bypass and demand pump and valve system for bypass and demand pump.
The applicant listed for this patent is Delavan AG Pumps, Inc.. Invention is credited to David BEAUDRY, Logan CIPALA, Matt JOHNSON.
Application Number | 20200011320 16/460729 |
Document ID | / |
Family ID | 69101364 |
Filed Date | 2020-01-09 |
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United States Patent
Application |
20200011320 |
Kind Code |
A1 |
CIPALA; Logan ; et
al. |
January 9, 2020 |
BYPASS AND DEMAND PUMP AND VALVE SYSTEM FOR BYPASS AND DEMAND
PUMP
Abstract
A diaphragm pump such as a three-chamber diaphragm pump includes
a head having an inlet port and an outlet port and defining an
inlet side including inlet chambers; and an outlet side having a
center outlet chamber. Each of the inlet chambers includes an
associated inlet valve. A single shutoff valve controlling fluid
flow to the center outlet chamber and a single bypass valve in
fluid communication between the center outlet chamber and the inlet
side. The single shutoff valve has a plunger with an oval
cross-section extending into the center outlet chamber. The single
shutoff valve and the single bypass valve have adjustable pressure
set points that are adjustable independently of one another.
Inventors: |
CIPALA; Logan; (Ellsworth,
WI) ; JOHNSON; Matt; (Champlin, MN) ; BEAUDRY;
David; (Minneapolis, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Delavan AG Pumps, Inc. |
Minneapolis |
MN |
US |
|
|
Family ID: |
69101364 |
Appl. No.: |
16/460729 |
Filed: |
July 2, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62693781 |
Jul 3, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 43/04 20130101;
F16K 27/003 20130101; F04B 43/02 20130101; F04B 49/24 20130101;
F04B 43/026 20130101; F04B 53/16 20130101; F16K 1/301 20130101 |
International
Class: |
F04B 43/02 20060101
F04B043/02; F16K 1/30 20060101 F16K001/30; F16K 27/00 20060101
F16K027/00 |
Claims
1. A diaphragm pump comprising: a head comprising an inlet port and
an outlet port and defining an inlet side including a plurality of
inlet chambers; and an outlet side having a center outlet chamber
intermediate the plurality of chambers; a plurality of inlet
valves, wherein each of the inlet chambers includes an associated
inlet valve; a single shutoff valve controlling fluid flow to the
center outlet chamber; a single bypass valve in fluid communication
between the center outlet chamber and the inlet side.
2. A diaphragm pump according to claim 1, the single shutoff valve
comprising a plunger extending into the center outlet chamber.
3. A diaphragm pump according to claim 2, wherein the plunger
comprises an oval cross section.
4. A diaphragm pump according to claim 1, wherein the plunger
comprises a stem, the stem including a recess receiving a
spring.
5. A diaphragm pump according to claim 1, wherein the plunger
comprises a head with an oval cross section and a stem connected to
the head, the stem including a recess receiving a spring.
6. A diaphragm pump according to claim 1, wherein the single
shutoff valve and the single bypass valve have adjustable pressure
set points.
7. A diaphragm pump according to claim 6, wherein the pressure set
points are independently adjustable.
9. A diaphragm pump according to claim 1, wherein the pump
comprises three inlet chambers.
10. A diaphragm pump according to claim 1, wherein head comprises
three inlet chambers arranged in a triangular configuration with
the central outlet chamber intermediate the three inlet
chambers.
11. A diaphragm pump according to claim 1, further comprising a
wobbler device actuating the inlet valves.
12. A diaphragm pump according to claim 1, comprising a single
shutoff switch.
13. A diaphragm pump system comprising: a head having a modular
upper housing assembly, the modular housing assembly comprising: a
first interchangeable upper housing assembly configured for
operation of the pump system solely as a demand pump; a second
interchangeable upper housing assembly configured for operation of
the pump system solely as a bypass pump; a third interchangeable
upper housing assembly configured for operation of the pump system
as a demand pump or as a bypass pump.
14. A diaphragm pump system according to claim 13, wherein each of
the interchangeable upper housing assemblies includes three
chambers in a triangular configuration and a central outlet chamber
intermediate the three chambers.
15. A method for making an upper housing of a diaphragm pump, the
method comprising: molding using a first mold for creating a first
interchangeable housing; or molding with the first mold and a first
insert for creating a second interchangeable housing; or molding
with the first mold and a second insert different from the first
insert for creating a second interchangeable housing.
16. A method according to claim 15, comprising adding a switch to
the diaphragm pump housing created with only the first mold.
17. A method according to claim 15, comprising adding an attachment
to the diaphragm pump housing created with the first mold and the
first insert.
18. A method of operating a diaphragm pump as a demand pump and as
a bypass pump, the diaphragm pump comprising: a head comprising an
inlet port and an outlet port and defining an inlet side including
a plurality of inlet chambers; and an outlet side having a center
outlet chamber intermediate the plurality of chambers; a plurality
of inlet valves, wherein each of the inlet chambers includes an
associated inlet valve; a single shutoff valve controlling fluid
flow to the center outlet chamber; a single bypass valve in fluid
communication between the center outlet chamber and the inlet side;
the method comprising: setting the single shutoff valve to a
predetermined shutoff pressure; and setting the single bypass valve
to a predetermined bypass pressure.
19. A method of operating a diaphragm pump as a demand pump and as
a bypass pump according to claim 18, wherein the bypass pressure is
greater than the shutoff pressure.
20. A method of operating a diaphragm pump as a demand pump and as
a bypass pump according to claim 18, wherein the bypass pressure
and shutoff pressure are independently adjustable.
21. A method of operating a diaphragm pump as a demand pump and as
a bypass pump according to claim 18, wherein the bypass pressure
and shutoff pressure are independently adjustable from an exterior
of the pump.
22. A head for a diaphragm pump; the head comprising: an inlet port
and an outlet port and defining an inlet side including a plurality
of inlet chambers; and an outlet side having a center outlet
chamber intermediate the plurality of chambers; a plurality of
inlet valves, wherein each of the inlet chambers includes an
associated inlet valve; a single shutoff valve controlling fluid
flow to the center outlet chamber; a single bypass valve in fluid
communication between the center outlet chamber and the inlet side.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention is directed to an improved pump and
valve system operable in a bypass mode and a demand mode and to a
method of operating such a pump.
Description of the Prior Art
[0002] Positive displacement pumps and in particular diaphragm
pumps, are used for various types of applications. Depending upon
the type of application, the requirements for the pump and
controlling flow and pressure may vary widely. Such pumps are often
broadly categorized as either a demand pump or a bypass pump.
[0003] Demand type pumps are often used where a set flow and
pressure are required. Common applications may include a spray wand
for agricultural spot spraying. For such a use, when the release
valve such as found in a wand is closed, pressure increases to a
preset limit and the pressure switch shuts off the motor. However,
the pump has valves that trap pressure in the line. Therefore, when
the end release valve is open, the wand is turned back on and
pressure in the line may decrease until falling below a set point
that restarts the pump. Operating in such a demand mode is
typically more stressful to the pump. However, this may not be a
satisfactory configuration where variable rates are required.
[0004] In contrast to demand pumps, bypass pumps are suited for use
where a wide range of flows and pressures may be required. An
example of a common use as is a spray bar having nozzles that are
independently controlled and may have independent flow needs. In a
bypass pump, the pump remains on regardless of the pressure in the
system. For such systems, flow rate may vary such as when one
nozzle is in operation as opposed to two or more nozzles are being
utilized. If there are nozzles that are not utilized, the excess
flow is not delivered from the pump, but is bypassed within the
pump. Such pumps must be configured to accommodate the highest flow
requirements for the system. Bypass pumps prevent problems
associated with repeated on and off cycling of the pumps, which may
burn out the pump motor.
[0005] Although it may be possible to utilize both a bypass
operating configuration and a demand operating configuration, the
added control and flow for each operating mode typically requires
additional control and/or flow elements that may enlarge the pump
and may make it impractical for many applications. Although pumps
have been developed that may be able to function as a demand pump
or a bypass pump, the compact configuration of lower flow diaphragm
pumps does not provide sufficient space for valves and controls to
operate satisfactorily in both demand mode and a bypass mode
without increasing the size of the head.
[0006] Moreover, demand pumps and bypass pumps of similar
capacities require different housings. The same capacity bypass
pump and demand pump would typically have a different style
housing. The manufacture of such housings, which are typically
molded, would be improved if a single mold with removable mold
inserts could be utilized in a method for creating a bypass pump
housing, a demand pump housing, or a combination bypass and demand
pump housing mountable to the same motor.
[0007] It can be seen then that a new and improved pump and valve
system are needed that can be operated as both a demand pump and as
a bypass pump. Moreover, such a pump should be simple and
inexpensive to manufacture. Such a pump should be sufficiently
compact and have a compact valve system so that it does not occupy
additional volume to make the valve system impractical. Moreover,
such a pump system should be configured so that the same housing
may be utilized with different mold inserts to allow for making
interchangeable housings for a demand pump, for a bypass pump, or
for a combination demand and bypass pump. The demand and bypass
pressure settings should be adjustable independently of one another
in the same pump. The present invention addresses these as well as
other problems associated with demand and bypass pumps.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to a diaphragm pump with a
valve system operable in bypass mode and in a demand mode. The pump
includes a head and a motor. The head includes a lower housing
assembly and an upper housing assembly. A valve plate assembly is
mounted intermediate the upper housing assembly and the lower
housing assembly. A shutoff switch housing mounts to the upper
housing assembly.
[0009] A drive shaft extends from the motor, drives the components
in the head, and operates the diaphragm and valves. A cam mounts on
the drive shaft and within a bearing and drives a wobbler. As the
drive shaft rotates the wobbler or wobble plate with a face angled
at approximately 3-4.5 degrees "wobbles" to convert axial motion
into linear motion of the wobbler. The linear motion of the wobbler
stretches and deforms the diaphragm to create a pumping action. The
pump may typically include three or more chambers and includes an
inlet valve for each chamber. As the wobbler rotates and oscillates
back and forth by the cam, the diaphragm is deformed back and forth
to pump fluid. The valves fit into the valve plate assembly that
spaces the three valves and chambers and is engaged by the
diaphragm. The discharge valve mounts on the opposite side of the
valve plate assembly. The discharge valve forms a seal that engages
an inner portion of the upper housing assembly, as explained
hereinafter.
[0010] The upper housing assembly includes sliding connectors at
the fluid ports. Such connectors allow for snapping in
complementary fluid lines to provide a quick disconnect.
Alternatively, the ports may have a conventional threaded connector
for connection to a complementary threaded connector of a fluid
line. The connectors are able to accommodate adapters to mount
fluid lines of different diameters to the pump.
[0011] The pumped fluid generally flows into an inlet port through
the head and exits out an outlet port. The pumped fluid is
initially drawn from the inlet port into the pumping chambers
through the valve plate assembly by the diaphragm. The pumped fluid
then passes through an opening in the center of the valve plate
assembly and through the outlet cavity to the outlet port.
[0012] The pump of the present invention is configured for
operation as either a bypass pump or a demand pump. To accomplish
this dual operation, a switch adapter mounts to the upper housing
and provides for mounting the shutoff valve switch assembly for the
shutoff valve to the upper housing. The switch adapter includes a
gasket on one side and a neoprene seal on the opposite face. The
upper housing also receives a bypass valve housing in a triangular
recess aligned with the bypass valve. The bypass valve includes a
flexible disc received in a complementary shutoff valve chamber
formed in the upper housing. The bypass valve chamber also spans
the interior and exterior of the outlet cavity. The triangular
recess on the exterior of the upper housing leads to the bypass
valve chamber in the interior of the upper housing assembly. A
bypass spring is engaged by guides that seat in the bypass valve
housing. An adjustment screw engages the bypass spring and provides
for setting a pressure at which fluid bypasses the outlet, as
explained hereinafter. Rotation of the adjustment screw in a first
direction compresses the bypass spring and rotation of the
adjustment screw in an opposite direction allows the bypass spring
to extend, thereby providing for adjustment of the force of the
spring acting on the disc and to control the backpressure at which
the disc deforms and allows fluid to pass.
[0013] In addition, the pump functions as a demand pump with a
shutoff switch including a housing base, a switch lever arm, a low
pressure spring, and a micro-switch, all fitting into the switch
housing, mounting onto the upper housing. The shutoff pressure may
be adjusted independently by turning shutoff valve low pressure
adjustment screw. Both the bypass pressure and the low pressure
operating points for the pump can be manually adjusted
independently by accessing the bypass adjustment screw and the
low-pressure adjustment screw from the exterior of the pump.
However, the pressure points are typically set at the factory with
customers prescribing a particular bypass pressure setting and a
low pressure shutoff setting. It can also be appreciated that the
two pressure set points for bypass and shutoff are independently
adjustable of one another without removal of the head or any
components. With both a shutoff valve and a bypass valve, the pump
is always in both a demand and a shutoff mode and has the superior
characteristics and advantages of each type of pump.
[0014] The three chambers each have an inlet valve and are opened
and closed as the wobbler rotates and stretches and deforms the
molded diaphragm. An oval shaped outlet cavity is formed by a
cavity wall. The outlet cavity at least partially intersects with
each of the three chambers. The check valve includes a plunger
biased by a plunger spring. An oval O-ring provides a seal against
an oval cylinder receiving the plunger. It can be appreciated that
the oval shape of the plunger provides for sufficient volume and
overlap with each of the three chambers. The present invention
therefore avoids having three separate bypass valves for each of
the three chambers. The present invention saves further space by
having the plunger spring positioned within a void formed in the
stem extending from the plunger.
[0015] The outlet chamber is also shaped as an oval to mate to the
oval outlet cavity and includes both a full circular valve portion
as well as a semi-circular valve portion to adapt to the oval
configuration. The location and shape of the outlet valve provides
for fluid communication with each of the triangular spaced
chambers. Moreover, the wobble plate provides for deforming
different portions of the diaphragm so that at all times, one of
the chambers is substantially closed, one of the chambers is
substantially pumping fluid out and one of the chambers is drawing
fluid into the chamber. Therefore, constant flow is maintained
while the pump is in operation.
[0016] In operation, the pump may be shut off with zero flow; in
another operating condition, the pump may be in a free flowing
operating condition; and in a further operating condition, the pump
may be operating, but bypassing fluid. In the first operating
condition, there is no flow inside the pump head. The shutoff check
valve is in the fully closed position and the bypass valve is in
the fully closed position. In such a state, there is insufficient
demand or backpressure to open the shutoff valve.
[0017] In a second operating condition, the pump is in an open flow
condition with no restriction and no backpressure inside the pump
head. The shutoff check valve is in a fully opened position.
Moreover, the bypass valve remains fully closed. There is no
backpressure within the head and all fluid to be pumped passes
through the pump.
[0018] In a third operating condition, the pump is in a bypass
mode. There is restricted flow inside the pump head and there is
built up backpressure. The shutoff check valve is in a fully open
position. The bypass valve is in an open position due to
restriction of flow and the associated backpressure. In such a
condition, the flexible stamped disc is deformed to act as a valve
member and allow the fluid to bypass back into the pump head. The
fluid to be pumped flows through the bypass valve chamber and
circulates within the head in the volume exterior of the outlet
cavity and on the inlet side of the upper housing. The pump remains
in this state until there is sufficient pressure so that the
shutoff valve engages. The pump of the present invention therefore
avoids the problems related to repetitive cycling on and off and
possibly burning out pump motors and wearing other pump
elements.
[0019] It can be appreciated that the compact geometry of the pump
head is critical in achieving a demand and bypass pump that is
operable in both modes and has each of the pressure points
adjustable independently. Moreover, the present invention is able
to achieve such a demand and bypass pump with a single shutoff
switch and a single check valve. The oval geometry of the plunger
and the complimentary oval cylinder achieve a sufficient valve area
to function in a satisfactory manner without requiring enlargement
of the surrounding pump components. Moreover, the bypass valve
chamber and the bypass valve are also configured for providing
operation to the multiple chambers with a single bypass valve.
[0020] The unique geometry also achieves production advantages for
such a pump. The upper housing assembly provides for receiving both
a shutoff switch assembly, a check valve and a bypass valve
assembly. However, for many applications, such flexibility of both
demand and bypass may not be needed. With the present invention,
the molded upper housing assembly may simply include a separate
insert to block the shutoff check valve for use while retaining the
bypass valve so that the pump is a bypass valve and functions in
that mode. However, with a second different insert, the head may be
molded with the bypass valve blocked, while the shutoff valve
remains so that the pump functions as a demand pump. In a third
configuration of molding the upper housing assembly, the mold is
configured so that both the oval cylinder and bypass valve chamber
are molded into the upper housing assembly. Therefore, the same
basic housing assembly with different mold inserts may be molded
for use as a demand pump, for use as a bypass pump, or for use as a
combination bypass and demand pump. The other shutoff valve
components are simply eliminated if the pump is configured as a
bypass pump and the other bypass valve components are eliminated if
the pump is configured as a demand pump.
[0021] These features of novelty and various other advantages that
characterize the invention are pointed out with particularity in
the claims annexed hereto and forming a part hereof. However, for a
better understanding of the invention, its advantages, and the
objects obtained by its use, reference should be made to the
drawings that form a further part hereof, and to the accompanying
descriptive matter, in which there is illustrated and described a
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Referring now to the drawings, wherein like reference
numerals and letters indicate corresponding structure throughout
the several views:
[0023] FIG. 1 is a perspective view of a pump according to the
principles of the present invention;
[0024] FIG. 2 is an exploded perspective view of the pump in FIG.
1;
[0025] FIG. 3 is a front elevational view of the upper housing
assembly for the pump shown in FIG. 1;
[0026] FIG. 4 is a rear elevational view of the upper housing
assembly shown in FIG. 3;
[0027] FIG. 5 is a side view of the upper housing assembly shown in
FIG. 3;
[0028] FIG. 6 is an exploded view of the upper housing assembly
shown in FIG. 3;
[0029] FIG. 7 is a sectional view taken along line 7-7 of FIG. 4
with the pump in a first operating condition with the check valve
and the bypass valve both fully closed and no flow inside the
head;
[0030] FIG. 8 is a sectional view taken along line 7-7 of FIG. 4
with the pump in a second operating condition with the check valve
fully open, the bypass valve fully closed and open flow in the
head;
[0031] FIG. 9 is a sectional view taken along line 7-7 of FIG. 4
with the pump in a third operating condition with the check valve
fully open, the bypass valve open due to back pressure and
restricted flow in the head;
[0032] FIG. 10 is a sectional view taken along line 10-10 of FIG. 4
and fluid flow through the upper housing assembly; and
[0033] FIG. 11 is an exploded side view of the head showing fluid
flow.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] Referring now to the drawings and in particular to FIG. 1,
there is shown a diaphragm pump, generally designated (100). The
pump (100) includes a head (102) and a motor (104). The pump (100)
mounts with a bracket (180) to other structure and is powered by a
cord (182). The head (102) includes a lower housing assembly (106)
and an upper housing assembly (110). A valve plate housing assembly
(108) is mounted intermediate the upper housing assembly (110) and
the lower housing assembly (106). A shutoff valve housing (150)
mounts to the upper housing assembly (110). The housings (106, 108,
110, 150) are connected together and to the motor (104) with
hardware (168).
[0035] Referring now to FIG. 2, extending from the motor (104) is a
drive shaft (126) that drives the components in the head (102) and
actuates a molded diaphragm (116) and valves (114) and (122). A cam
(118) mounts on the drive shaft (126) and within a bearing (120)
and drives a wobbler (112). As the drive shaft (126) rotates the
wobbler (112) or wobble plate moves with an angled face at an angle
of approximately 3-4.5 degrees to convert axial motion into linear
motion of the wobbler (112). The linear motion of the wobbler (112)
stretches and deforms portions of the molded diaphragm (116). In
the embodiment shown, the pump (100) includes three chambers and
includes three inlet valves (114). As the wobbler (112) rotates and
oscillates back and forth or "wobbles" by the cam (118), the fluid
is pumped through the upper housing assembly (110). The inlet
valves (114) fit into the valve plate assembly (108) that spaces
the three valves and chambers and are engaged by the diaphragm
(116). The discharge valve (122) mounts on the opposite side of the
valve plate assembly (108). The discharge valve (122) forms a seal
(124) that engages an inner portion of the upper housing assembly
(110), as explained hereinafter.
[0036] The head (102) includes sliding connectors (172) at inlet
fluid port (170A) and outlet port (170B). Such connectors (172)
allow for a quick connect/disconnect of complementary fluid lines.
It can also be appreciated that the ports (170A, 170B) may have
conventional threaded connectors for connection to complementary
threaded connectors of a fluid line. The sliding connectors (172)
are able to accommodate an adapter to mount fluid lines of
different diameters to the pump (100).
[0037] Referring now to FIG. 11, there is shown the general fluid
flow through the pump head (102). The pumped fluid generally flows
through an inlet port (170A) through the head (102) and exits
through an outlet port (170B). The pumped fluid is initially drawn
from the inlet port (170A) into the pumping chambers (200A), (200B)
and (200C) through the valve plate assembly (108) by the diaphragm
(116). The pumped fluid then passes through an opening in the
center of the valve housing plate (108) and through the outlet
cavity (202) to the outlet port (170B).
[0038] The pump (100) of the present invention is configured for
operation as a bypass pump and as a demand pump. As shown in FIGS.
3-6, to accomplish this dual operation, a shutoff check valve (128)
is actuated by a shutoff valve switch (140) that attaches to a
switch adapter (138) mounted to the upper housing (110) and
provides for mounting the shutoff valve switch assembly (140) to
the upper housing (110). The switch adapter (138) includes an
O-ring (136) on one side and a seal (154) on the opposite face.
[0039] A bypass valve (156) includes a bypass valve housing (164)
inserting into a triangular recess (210) in the exterior of the
upper housing (110) aligned with a bypass valve chamber (208) on
the interior of the upper housing (110). The bypass valve (156)
includes a flexible disc (158) received in a complementary bypass
valve chamber (208) formed in the upper housing (110). The bypass
valve chamber (208) intersects the interior and exterior of the
outlet cavity (202), as shown in FIG. 4. The triangular recess
(210) on the exterior of the upper housing (110) leads to and
fluidly connects to the bypass valve chamber (208) in the interior
of the upper housing assembly (110). A bypass spring (160) is
engaged by guides (162) that seat into the bypass valve housing
(164). Adjustment screw (166) engages the bypass spring (160) and
provides for setting a pressure at which fluid bypasses the outlet,
as explained hereinafter. Rotation of the adjustment screw (166) in
a first direction compresses the bypass spring (160) and rotation
of the adjustment screw (166) in an opposite direction allows the
bypass spring (160) to extend, thereby providing for adjustment of
the force of the spring (160) acting on the disc (158) to control
the backpressure at which the disc (158) deforms and allows fluid
to pass.
[0040] In addition, the pump (100) functions as a demand pump with
the check valve (128) controlled by the shutoff switch (140). The
shutoff switch assembly (140) includes a housing base (144), a
shutoff switch lever arm (142), a low pressure spring (146), and a
micro-switch (160), all fitting into the shutoff switch housing
(150), mounting onto the upper housing (110). The shutoff pressure
may be adjusted independently by turning shutoff valve low pressure
adjustment screw (152). Rotation of the adjustment screw (152) in a
first direction compresses the low pressure spring (146) and
rotation of the adjustment screw (152) in an opposite direction
allows the low pressure spring (146) to extend, thereby providing
for adjustment of the force of the spring (146) acting on the
shutoff switch lever arm (142) and to control the pressure at which
the micro-switch (160) activates to open or close the check valve
(128) and allow fluid to pass. Therefore, both the bypass pressure
and the low pressure operating points for the pump (100) can be
manually adjusted independently by accessing the bypass adjustment
screw (166) and the low pressure adjustment screw (152) from the
exterior of the pump (100). However, the pressure points are
typically set at the factory with customers prescribing a
particular bypass pressure setting and a low pressure shutoff
setting. It is also appreciated that the two pressure set points
for bypass and shutoff are independently adjustable of one another
without removal of the head or any components. As the pump (100)
has both a shutoff valve (128) and a bypass valve (156), the pump
(100) is always in both a demand mode and a shutoff mode and has
the superior characteristics and advantages of each type of
pump.
[0041] The three chambers (200A), (200B), (200C) each have an inlet
valve (114) and are opened and closed as the wobbler (112) rotates
to deform portions of the molded diaphragm (116). An oval outlet
cavity (202) is formed by a cavity wall (204). The outlet cavity at
least partially intersects with each of the three chambers (200A),
(200B), (200C). The bypass valve (156) includes a plunger (130)
biased by a plunger spring (132). An oval gasket (134) provides a
seal against an oval cylinder (206) receiving the plunger (132). It
can be appreciated that the oval shape of the plunger (130)
provides for sufficient volume in a small space with the outlet
cavity (202) that overlaps with each of the three chambers (200A),
(200B) and (200C). The present invention therefore avoids having
three separate bypass valves, one for each of the three chambers,
as needed with other systems. The present invention saves further
space by having the plunger spring (132) within a cylindrical space
formed in the rod extending from the back of the plunger (130).
[0042] The outlet valve (122) is a molded element shaped as an oval
to mate to the oval outlet cavity (202) and includes both a full
circular valve portion as well as a semi-circular valve portion to
adapt to the oval configuration. The location and shape of the
outlet valve (122) and outlet cavity (202) provides for fluid
communication with each of the triangular spaced chambers (200A),
(200B) and (200C). Moreover, the wobble plate (112) provides for
stretching the diaphragm (116) so that at all times, one of the
chambers (200A), (200B) or (200C) is substantially closed; one of
the chambers is substantially pumping fluid out; and one of the
chambers is drawing fluid into the chamber. Therefore, constant
flow is maintained while the pump (100) is in operation.
[0043] In operation, the pump (100) the pump (100) may be shut off
with zero flow; in another operating condition, the pump (100) may
be in a freely flowing operating condition; and in a further
operating condition, the pump (100) may be bypassing fluid.
Referring now to FIGS. 7-9, the pump configuration of each of the
modes and operating conditions is shown. In FIG. 7, there is no
flow inside the pump head (102). The shutoff check valve (128) is
in the fully closed position and the bypass valve (156) is in the
fully closed position. In such a state, there is insufficient
demand or backpressure to open the shutoff valve (128).
[0044] Referring now to FIG. 8, the pump (100) is in an open flow
operating condition with no restriction and no backpressure inside
the pump head (102). The shutoff check valve (128) is in a fully
opened position. Moreover, the bypass valve (156) remains fully
closed. There is no backpressure within the head (102) and all
fluid to be pumped flows through the pump (100).
[0045] Referring to FIG. 9, the pump is in a bypass operating
condition. There is restricted flow inside the pump head (102) and
there is built up backpressure. The shutoff check valve (128) is in
an open position. The bypass valve (156) is in an open position due
to restriction of flow and the associated backpressure. In such a
condition, the flexible stamped disc (158) bows outward. When the
disc (158) is deformed in this manner, the disc (158) acts as a
valve member and allows the fluid to flow around the periphery of
the disc (158) and bypass back into the pump head (102). The fluid
to be pumped flows through the bypass valve chamber (208) and
circulates within the head (102) in the volume exterior of the
outlet cavity (202) and on the inlet side of the upper housing
(110). The pump (100) remains in this state until there is
sufficient pressure that the shutoff valve (128) engages. The pump
(100) of the present invention therefore avoids the problems
related to repetitive cycling on and off and burning out pump
motors and wearing other pump elements.
[0046] It can be appreciated that the geometry of the pump head
(102) is critical in achieving a demand and bypass pump that is
operable in both demand and bypass modes and has each of the
pressure points adjustable independently. Moreover, the present
invention is able to achieve such a demand and bypass pump with a
single check valve (128) and a single bypass valve (156). The oval
geometry of the plunger (130) and the complimentary oval cylinder
(206) achieve a sufficient valve area to function in a satisfactory
manner without requiring enlargement or rearrangement of the
surrounding pump components. Moreover, the bypass valve chamber
(208) and the bypass valve (156) are also configured for providing
operation to all of the multiple chambers with a same single bypass
valve. The oval profile of the plunger (130) and cylinder (206)
also achieve adequate engagement and sealing.
[0047] The unique geometry also provides for advantages for
producing such a pump. It can be appreciated that in the embodiment
shown, the upper housing assembly (110) provides for receiving both
a shutoff valve assembly (128) and a bypass valve assembly (156).
However, for certain applications, such flexibility of both demand
and bypass may not be needed. With the present invention, the
molded upper housing assembly (110) may simply include a separate
insert to block the shutoff check valve for use while retaining the
bypass valve so that the pump is a bypass valve and functions in
that mode. However, with a second insert, the head (102) may be
molded with the bypass valve blocked, while the shutoff valve (128)
remains so that the pump functions as a demand pump. In a third
configuration of molding the upper housing assembly (110), the mold
is configured so that both the oval cylinder (206) and bypass valve
chamber (208) are molded into the upper housing assembly (110).
Therefore, the same basic housing assembly with different mold
inserts may be molded for use as a demand pump, for use as a bypass
pump, or for use as a combination bypass and demand pump. The inlet
and outlet valves and chambers do not need to be modified.
Moreover, the shutoff valve components are simply eliminated if the
pump is configured as a bypass pump and the bypass valve components
are simply eliminated if the pump is configured as a demand
pump.
[0048] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
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