U.S. patent number 3,711,222 [Application Number 05/105,544] was granted by the patent office on 1973-01-16 for pumping system.
Invention is credited to Ezra D. Hartley.
United States Patent |
3,711,222 |
Hartley |
January 16, 1973 |
PUMPING SYSTEM
Abstract
A pumping system comprising a pump, a drive mechanism for
driving the pump, and a differential pressure switch responsive to
the pressure of the fluid in a sensing zone on a discharge side of
the pump for turning the pump on and off. A restricted fluid
passage is interposed between the pump discharge and the sensing
zone.
Inventors: |
Hartley; Ezra D. (Los Angeles,
CA) |
Family
ID: |
22306422 |
Appl.
No.: |
05/105,544 |
Filed: |
January 11, 1971 |
Current U.S.
Class: |
417/44.9;
200/83J |
Current CPC
Class: |
F04C
14/06 (20130101) |
Current International
Class: |
F04B
49/00 (20060101); F04b 049/00 () |
Field of
Search: |
;200/82C,82A,83T,83S,83SA,89.1 ;417/44,38 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kaufman; Milton
Assistant Examiner: Grossman; Barry
Claims
I claim:
1. A pumping unit comprising:
a pump for moving a fluid;
drive means for driving the pump;
a pressure responsive member;
means defining a valve seat;
conduit means for providing communication between the discharge
side of said pump and the valve seat;
means for mounting said pressure responsive member for movement
between a low pressure position in which said pressure responsive
member engages said valve seat and a first area of said pressure
responsive member is exposed to the fluid pressure and a high
pressure position in which said pressure responsive member is moved
away from said valve seat to expose a second area of the pressure
responsive member to the fluid;
yieldable means for urging said pressure responsive member toward
the low pressure position, said second area having a greater
effective area than the first area whereby the pressure responsive
member is moved from the low pressure to the high pressure position
in response to a first pressure level and cannot return from the
high pressure position to the low pressure position until the
pressure level drops below the first pressure level;
first means responsive to movement of the pressure responsive
member to the low pressure position for causing said drive means to
drive said pump and responsive to movement of the pressure
responsive member to the high pressure position for causing said
drive means to cease driving said pump; and
said conduit means including a restricted passage section of
relatively small cross sectional area intermediate said pressure
responsive member and the pump discharge to thereby interpose a
time delay between the instant at which a change in the pressure of
the fluid on one side of said restricted passage section occurs and
the instant at which such change occurs on the other side of said
restricted passage section.
2. A pumping unit as defined in claim 1 wherein said restricted
passage section includes means defining a circumscribing passage
section.
3. A pumping unit as defined in claim 1 including a restrictor
member in said conduit means defining said restricted passage
section, said restricted passage section circumscribing said
restrictor member, said first means including a switch having an
actuating member engageable with said pressure responsive member at
least in said high pressure position, a flexible valve element
mounted on said restrictor member adjacent the upstream end of said
restricted passage section, means defining a valve seat against
which the flexible valve element can bear, and a support member on
the upstream side of said flexible valve element for supporting the
latter, said support member having means defining an opening
therethrough.
4. A pumping unit as defined in claim 1 including a housing, a
first wall dividing said housing into an inlet chamber and an
outlet chamber, said pump being in said housing and having an inlet
and an outlet communicating with said inlet chamber and said outlet
chamber, respectively, said pressure responsive member being at a
sensing zone, a second wall separating said sensing zone from said
outlet chamber, said second wall having an aperture therein and
said first wall having a restrictor member thereon projecting into
said aperture to define said restricted passage section between
said outlet chamber and said sensing zone.
5. A pumping unit comprising:
a pump for moving a fluid;
drive means for driving the pump;
means defining a fluid passage for conducting the fluid from the
discharge side of said pump;
wall means defining a conduit leading from said fluid passage;
a restrictor member in said conduit and spaced from said wall means
by a radially narrow clearance space which substantially
circumscribes the restrictor member to define a restricted passage
section, said conduit on the side of said restricted passage
section downstream from said fluid passage defining a sensing zone
with said restricted passage section causing a time delay for the
transmission of pressure changes between said sensing zone and the
other side of said restricted passage section; and
means responsive to a first fluid pressure level at said sensing
zone for causing said drive means to drive said pump and responsive
to a second fluid pressure level at said sensing zone for causing
said drive means to cease driving said pump, said second level
being higher than said first level.
6. A pumping unit as defined in claim 5 including a flexible valve
element mounted on said restrictor member adjacent the upstream end
of said restricted passage section, means defining a valve seat
against which the flexible valve element can bear, and disc-like
support means mounted on the upstream side of said flexible valve
element for supporting said flexible valve element against
substantial movement in the upstream direction whereby said
flexible valve element serves as a check valve to prevent reverse
flow to the pump, said support means having means defining at least
one opening therethrough.
7. A device responsive to fluid under a variable pressure
comprising:
a conduit for conducting the fluid under pressure from a first zone
to a second zone;
means defining a restriction in said conduit between said zones,
said restriction delaying the flow of fluid between said zones to
thereby interpose a time delay between the instant at which a
pressure change occurs at said first zone and the instant at which
such change occurs at said second zone;
a pressure responsive member;
means defining a valve seat at said second zone;
means for mounting said pressure responsive member for movement
between a low pressure position in which said pressure responsive
member engages said valve seat and a first area of said piston is
exposed to the fluid under pressure and a high pressure position in
which said pressure responsive member is moved away from said seat
to expose a second area of the piston to the fluid under
pressure;
yieldable means for urging the pressure responsive member toward
the low pressure position;
said second area having a greater effective area than said first
area whereby the pressure responsive member is moved from the low
pressure position to the high pressure position in response to a
first pressure level at said second zone and cannot return from the
high pressure position to the low pressure position until the
pressure level at said second zone drops below the first pressure
level;
a control device for performing first and second control functions;
and
means responsive to movement of the pressure responsive member to
the low pressure position for causing said control device to
perform said first control function and responsive to movement of
the pressure responsive member to the high pressure position for
causing said control device to perform a second control
function.
8. A device as defined in claim 7 wherein said control device
includes a switch having an actuating member for causing the switch
to perform said control functions, said pressure responsive member
being engageable with said actuating member in said high pressure
position.
9. A device as defined in claim 7 including a restrictor member in
said conduit and spaced from the wall of said conduit to define
said restriction, said restriction circumscribing said restrictor
member.
10. A pumping unit comprising:
a pump for moving a fluid;
drive means for driving the pump;
a pressure responsive member;
means defining a valve seat;
conduit means for providing communication between the discharge
side of said pump and the valve seat;
means for mounting said pressure responsive member for movement
between a low pressure position in which said pressure responsive
member engages said valve seat and a first area of said pressure
responsive member is exposed to the fluid pressure and a high
pressure position in which said pressure responsive member is moved
away from said valve seat to expose a second area of the pressure
responsive member to the fluid;
yieldable means for urging said pressure responsive member toward
the low pressure position, said second area having a greater
effective area than the first area whereby the pressure responsive
member is moved from the low pressure position to the high pressure
position in response to a first pressure level and cannot return
from the high pressure position to the low pressure position until
the pressure level drops below the first pressure level;
first means responsive to the pressure responsive member being in
the low pressure position for causing said drive means to drive
said pump and responsive to the pressure responsive member being in
the high pressure position for causing said drive means to cease
driving said pump;
means defining a fluid passage leading from the pump discharge for
carrying the fluid from the pump discharge;
a check valve seat in said fluid passage;
a flexible washer-like valve element;
means for mounting said flexible valve element in said fluid
passage so that said flexible valve element can bear against said
check valve seat; and
a disc-like support member mounted on the upstream side of said
flexible valve element for supporting said flexible valve element
against substantial movement in the upstream direction wherein said
flexible valve element serves as a check valve to prevent backflow
to the pump, said support member having means defining at least one
opening therethrough.
Description
BACKGROUND OF THE INVENTION
Pumping systems typically include a pump for pumping liquid from a
source to a preselected destination and control means for
controlling the operation of the pump. In many pumping systems,
such as in a pumping system utilized for providing water in a
recreational vehicle, the control means turns the pump on in
response to the pressure downstream of the pump dropping to a
predetermined low level and turns the pump off when the downstream
pressure reaches a desired maximum level.
With this type of water supply system, the pump cycles on and off
substantially simultaneously with the opening and closing of the
faucet or other water utilization control valve. As the minimum
on-time for the faucet cannot be predicted and may be only a
fractional portion of a second, the pump may be cycled on and off
very rapidly. This may damage the pump and the pump motor. If the
water demand is low but continuous, the pump will cycle on and off
rapidly. This causes vibration and causes the water to spurt
through the faucet outlet rather than flow evenly.
To avoid rapid cycling of the pump, conventional systems employ an
accumulator. An accumulator, however, adds to the cost of the
system and to the cost of assembling the system. In addition, the
accumulator takes up space which is often at a premium in a
recreational vehicle.
SUMMARY OF THE INVENTION
The present invention provides a pumping system which eliminates
the accumulator and still prevents rapid cycling of the pump. This
invention establishes a minimum cycle time for the pump which is
substantially independent of the rate or frequency of fluid
utilization thereby providing protection for the pump and pump
motor. The minimum cycle time is set so as to avoid vibration and
the water spurting problem noted above.
The present invention uses two separate principles, either
individually or in combination, to establish the minimum cycle
time. Optimum results are achieved when the two principles are used
in combination.
First, the present invention uses a differential pressure control
device to turn the pump on when the pressure downstream thereof is
at a relatively low level and to turn the pump off when the
downstream pressure reaches a relatively high level. The time
required to obtain this pressure change constitutes a first
increment of the minimum cycle time.
The pressure levels to which the differential pressure control
device is responsive can be selected by those having ordinary skill
in the art. Generally, however, the larger the differential
pressure, the longer is the resulting time increment. On the other
hand, the size and cost of the unit generally increases as the
pressure differential is increased.
The differential pressure control device preferably includes a
pressure responsive member at a sensing zone, a valve seat, conduit
means for providing communication between the discharge side of the
pump and the sensing zone and means for mounting the pressure
responsive member for movement between the low pressure position in
which the pressure responsive member engages the valve seat and a
first area of the pressure responsive member is exposed to the
fluid pressure and a high pressure position in which the pressure
responsive member is moved away from the seat to expose a second
area of the piston to the fluid pressure. Yieldable means such as a
spring urges the pressure responsive member toward the low pressure
position. The second area includes the first area and has a greater
effective area. Accordingly, the pressure responsive member is a
differential area member.
The pressure responsive member is moved from the low pressure
position to the high pressure position in response to a relatively
high pressure and cannot return from the high pressure position to
the low pressure position until the pressure drops to a lower
level. The force of the yieldable means and the relative effective
areas of the first and second faces determine the differential
pressures at which the pressure control device is operative. This
construction is preferred because of its low cost, compactness and
simplicity.
The pressure responsive member can actuate various control devices
such as a switch for controlling the pump motor in various ways.
The pressure responsive member may engage the actuating member of a
switch in the high pressure position and be out of contact with the
actuating member in the low pressure position.
Secondly, the present invention uses a restriction between the pump
discharge and the sensing zone at which the pressure responsive
member senses system pressure. The restriction is sufficient to
provide a pressure drop thereby providing a time delay between the
instant at which a pressure change occurs in the system and the
instant at which a corresponding pressure change occurs at the
sensing zone. This constitutes the second increment of the minimum
time cycle and is additive with the first increment to establish
the minimum cycle time of the pump.
The time delay afforded by the restriction increases as the cross
sectional area of the restricted passage section decreases;
however, the effective area of the restricted passage section
should not be made too small because the tendency of the restricted
passage section to clog increases as the passage section is made
smaller.
To facilitate production particularly when the components of the
device are molded, the restriction can advantageously be formed as
a circumscribing passage. This can be accomplished by utilizing a
first member for defining a conduit and inserting a second member
into the first member with the two members being spaced by a
clearance space which circumscribes the inner member. It is much
easier to form the restriction in this manner than by molding a
small diameter hole.
Another feature of this invention is a novel check valve which can
be interposed between the pump discharge and the restricted passage
section. The check valve includes a flexible valve element of
washer-like configuration and a valve seat against which the
flexible valve element can be seated. To prevent collapse of the
flexible element, a support member on the upstream side of the
flexible valve element is provided. In order that fluid can flow
through the check valve with minimum resistance, the support member
preferably includes opening means.
The invention can best be understood by reference to the following
description taken in connection with the accompanying illustrative
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a pumping unit constructed in accordance
with the teachings of this invention.
FIG. 2 is a fragmentary side elevational view taken generally along
line 2--2 of FIG. 1.
FIG. 3 is a sectional view of the pumping unit taken generally
along line 3--3 of FIG. 1 and with other portions of a typical
water supply system being shown diagrammatically.
FIG. 4 is an enlarged sectional view showing the restricted passage
section and taken generally along line 4--4 of FIG. 3.
FIG. 5 is a sectional view taken generally along line 5--5 of FIG.
3.
FIG. 6 is an enlarged fragmentary plan view of the support member
for the flexible check valve element.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1-3 show a pumping unit 11 which generally includes housing
sections 13 and 15 each of which is preferably integrally molded of
plastic material. The housing section 13 defines an inlet 17 and an
outlet 19 adapted for connection to conduits leading to other
portions of a fluid system such as a source of water 20 and a water
distribution system 20a for a recreational system, respectively.
The distribution system 20a may include a plurality of water valves
20b. Water is drawn in through the inlet 17 by a pump 21 (FIG. 3)
which is driven by a motor 23 such as a dc motor with the motor
being drivingly connected to the pump 21 by an adaptor 25. The
motor 23 is turned on and off by a switch 27 which in turn is
controlled by the pressure responsive means of this invention.
More specifically, the housing sections 13 and 15 are
interconnected by a plurality of bolts 29 (FIGS. 1 and 2) and nuts
32. The pump 21 and a portion of the adaptor 25 are securely and
suitably mounted within the housing section 13, and the housing
section 13 is suitably affixed to the adaptor 25. Leakage from the
housing section 13 to the motor 23 is prevented by a seal 32. The
pump 21 is preferably a positive displacement pump such as a roller
pump; however, other pump constructions can be utilized.
With reference to FIGS. 3 and 5, the housing section 13 has a wall
33 which divides the housing into an inlet chamber 41 and an outlet
chamber 71. The wall has a pair of bosses 35 and 37 thereon which
define portions of the outlet chamber. Water enters the inlet 17
and passes through a filter 43 in the form of a screen which is
mounted in the inlet chamber 41.
The pump 21 in the embodiment illustrated has a pair of inlets 45
(the location of which is shown in dashed lines in FIG. 5) in the
inlet chamber 41 and a pair of outlets 47 (only one being shown in
FIG. 3) communicating with the passages formed by the bosses 35 and
37, respectively, and suitably sealed thereto. Accordingly, the
pump 21 draws water from the inlet chamber 41 into the inlets 45
and discharges the latter under pressure into the passages formed
by the bosses 35 and 37, respectively.
As shown in FIGS. 3 and 5, the wall 33 contains apertures 49 and 51
which communicate with the bosses 35 and 37, respectively. Back
flow through the apertures 49 and 51 is normally prevented by a
flexible valve element 53 which, in the embodiment illustrated, is
in the form of a rubber washer. The wall 33 defines a valve seat 55
against which the flexible valve element 53 can be seated by the
pressure downstream thereof. The wall 33 has a post or restrictor
member 57 projecting upwardly therefrom and the flexible valve
element 53 has an opening therein which permits the latter to be
mounted over the post. The flexible valve element 53 is retained in
position on the post 57 by a tubular section 59 of an isolating
plate 61 which clamps an inner annular region of the valve element
against the wall 33.
To prevent the fluid pressure downstream of the check valve 53 from
depressing the flexible valve element 53 into the ports defined by
the bosses 35 and 37, a thin disc-like support member 63 is mounted
on an annular shoulder 64 of the wall 33 immediately beneath the
post 57 and immediately upstream of the valve element as shown in
FIGS. 3 and 6. The support member 63 must possess sufficient
rigidity to support the flexible valve element 53 against collapse
and must underlie a sufficient area of the flexible valve element
to prevent such collapse.
A preferred configuration of the support member 63 is shown in FIG.
6, it being understood that other configurations suitable to
support the flexible valve element against collapse and provide it
with a capability of allowing water passage therethrough can also
be utilized. The support member 63 includes a peripheral ring
section 65 and a plurality of fingers 67 extending radially
inwardly of the ring section. The fingers 67 are circumferentially
spaced to define openings 69 to permit fluid passage through the
support member. In addition, the periphery of the support member 63
is spaced radially inwardly of the outer regions of the apertures
49 and 51 to provide further room for water passage. As shown in
FIG. 3, the ring section 65 of the support member 63 is curved
downwardly. The support member 63 is preferably constructed of a
thin sheet of metal such as stainless steel.
The water discharged by the pump 21 passes through the apertures 49
and 51 of the outlet chamber 71 and from there through the outlet
19 to the water distribution system 20a. To provide control of the
cycling of the pump 21, a radial port 73 and an annular restricted
passage section 75 (FIGS. 3 and 4) provide communication between
the outlet chamber 71 and a sensing zone 77. The isolating plate 61
separates the outlet chamber 71 from the sensing zone 77. The
restricted passage section 75 is in the form of an annular
clearance space between the post 57 and the tubular section 59 and,
in the embodiment illustrated, the post 57 and the interior of the
tubular section 59 are cylindrical and concentric.
A pressure responsive member such as a flexible diaphragm 79 is
clamped between the housing sections 13 and 15 and is adapted to
sealingly engage an annular valve seat 81 formed integrally with
the isolating plate 61. A plunger 83 is mounted for movement on the
side of the diaphragm 79 opposite the valve seat 81. The plunger 83
is biased toward the valve seat 81 by a coil spring 85.
Although different kinds of control devices could be used, the
illustrated embodiment of the invention employs the switch 27 as
the control device for the motor 23. The switch 27 has an actuating
member 87. With the actuating member fully extended as shown in
FIG. 3, the switch 27 closes the circuit to the motor 23 and with
the actuating member 87 depressed, i.e., moved further into the
housing of the switch 27, the switch opens the circuit to the motor
23. Although the switch 27 can be mounted in various ways, in the
embodiment illustrated the housing section 15 includes a bracket 89
(FIGS. 1 and 2) to which the switch 27 is secured by a pair of
threaded fasteners 91. The switch 27 has a pair of terminals 93 and
95 for attachment to the power supply circuit (not shown) to the
motor 23.
In operation of the device, the switch 27 controls the cycling of
the motor 23. Assuming that the components of the pumping unit 11
are in the low pressure position shown in FIG. 3, the switch 27
will complete a circuit to the motor 23 to energize the latter and
start the pump 21. The pump 21 draws in water through the inlet 17
and the inlet chamber 41 to the pump inlets 45 and discharges the
water through the pump outlets 47, the ports defined by the bosses
35 and 37 and the apertures 49 and 51. The pressure of the water in
the apertures 49 and 51 forces the flexible valve element 53 off
its seat and accordingly the water passes through the apertures and
the outlet 19 to the water distribution system 20a. Water flow
through the apertures 49 and 51 is assisted by the openings 69
(FIG. 6) and by the peripheral gap separating the support member 63
from the periphery of the apertures 49 and 51.
Some of the water in the outlet chamber 71 will flow through the
port 73 (FIGS. 3 and 4) and the restricted passage section 75 to
the sensing zone 77. As the pump continues to operate, the pressure
of the water in the outlet chamber 71 increases; however, because
of the small effective cross sectional area of the restricted
passage 75, there is a pressure drop thereacross. Accordingly,
there is a time delay between the instant at which a pressure
increase occurs in the outlet chamber 71 and the instant at which a
corresponding pressure change occurs at the sensing zone 77.
The pressure of the fluid in the sensing zone 77 acts on the area
of the diaphragm 79 which is circumscribed by the valve seat 81.
When the force acting on the diaphragm 79 exceeds the force of the
spring 85 urging the diaphragm against the seat 81, the diaphragm
is lifted off of the seat 81. As soon as the diaphragm 79 leaves
the valve seat 81, substantially the full area thereof is exposed
to fluid under pressure with the result that the diaphragm and the
plunger 83 snap upwardly to a high pressure position. In the high
pressure position, the plunger 83 engages the actuating member 87
of the switch 27 to open the circuit to the motor 23.
If the water pressure in the outlet chamber 79 decreases, as may
occur, for example, by utilization of the water in the distribution
system, there will be a corresponding decrease in pressure at the
sensing zone 77. However, such decrease in pressure at the sensing
zone 77 will lag the pressure drop in the outlet chamber 71 due to
the time delay interposed by the restricted passage section 75.
When the pressure at the sensing zone 77 multiplied by the full
exposed area of the diaphragm 79 drops to a value less than the
force of the spring 85, the spring is operative to urge the
diaphragm 79 back to the low pressure position in which the
diaphragm sealingly engages the valve seat 81. Because of the
differential areas of the diaphragm 79 which are exposed to the
fluid pressure in the low pressure and high pressure positions, the
diaphragm will not return to the low pressure position until the
pressure at the sensing zone is reduced substantially below the
value necessary to move the diaphragm to the high pressure
position.
It is apparent that the illustrated embodiment of the invention
operates to interpose a minimum on-time and a minimum off-time for
the pump 21 and motor 23 which are independent of the rate of
utilization of water by the water distribution system 20a. This
minimum cycle time is established by the time delay caused by the
restricted passage section 75 plus the time necessary to increase
or decrease the pressure at the sensing zone 77 an amount equal to
the difference in actuating pressures of the device.
The flexible valve element 53 remains open so long as the pressure
upstream thereof exceeds the downstream pressure. If this pressure
condition reverses, the downstream pressure urges the flexible
valve element 53 against the seat 55 to prevent reverse flow. The
support member 63 supports the flexible valve element 53 and
prevents it from being depressed into the apertures 49 and 51.
The pressure responsive control apparatus of this invention
including the restricted passage section 75 and the differential
area diaphragm 79 can obviously be utilized as a pressure
responsive device in other environments. The diaphragm 79 is not
limited to actuating a switch such as the switch 27. The check
valve formed by the flexible valve element 53, the seat 55 and the
support member 63 can also be utilized with other devices.
Although an exemplary embodiment of the invention has been shown
and described, many changes, modifications and substitutions may be
made by one having ordinary skill in the art without necessarily
departing from the spirit and scope of this invention.
* * * * *