U.S. patent number 3,816,034 [Application Number 05/362,727] was granted by the patent office on 1974-06-11 for diaphragm pumps and actuating system therefor.
This patent grant is currently assigned to Dorr-Oliver Incorporated. Invention is credited to John B. Rosenquest, Jr..
United States Patent |
3,816,034 |
Rosenquest, Jr. |
June 11, 1974 |
DIAPHRAGM PUMPS AND ACTUATING SYSTEM THEREFOR
Abstract
An improved fluid pressure-actuated timer controlled diaphragm
pump featuring an auxiliary or booster spring action device
containing spring means which store energy from the power stroke,
and release the energy to effect the return or suction stroke of
the diaphragm.
Inventors: |
Rosenquest, Jr.; John B. (New
Canaan, CT) |
Assignee: |
Dorr-Oliver Incorporated
(Stamford, CT)
|
Family
ID: |
26821760 |
Appl.
No.: |
05/362,727 |
Filed: |
May 22, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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123652 |
Mar 12, 1971 |
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Current U.S.
Class: |
417/395; 92/13.8;
92/13.2 |
Current CPC
Class: |
F04B
43/073 (20130101) |
Current International
Class: |
F04B
43/06 (20060101); F04B 43/073 (20060101); F04b
043/06 () |
Field of
Search: |
;417/392,394,395,390,401,454 ;92/13.2,13.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Husar; C. J.
Assistant Examiner: Smith; Leonard
Attorney, Agent or Firm: Kearns; Burtsell J. Jablon;
Theodore M.
Parent Case Text
This is a continuation, of application Ser. No. 123652, filed Mar.
12, 1971, now abandoned.
Claims
I claim:
1. A pumping system which comprises a diaphragm pump having a pump
housing, a diaphragm dividing the housing into a pumping chamber
having means for pump discharge and for pump intake, and a pump
actuating chamber having an opening substantially concentric with
said diaphragm, said actuating chamber adapted to receive a fluid
pressure medium acting upon the diaphragm to produce the pumping
stroke, and also adapted to be vented during a dwell period
following said pumping stroke during which period the fluid
pressure supply is interrupted to allow for the pump filling return
stroke of the diaphragm,
an actuating rod extending from said diaphragm through said
opening, so that a major portion of its length is outwardly exposed
of the pumping chamber,
a compression coil spring encircling said exposed length of rod,
confined between said opening in the pump chamber and an adjustable
stop means provided upon the outer end portion of said rod, said
stop means being operable to adjust the preload tension upon the
spring, and thus the energy storing capacity thereof, effective to
retract the diaphragm during said pump filling stroke,
a casing surrounding the exposed length of the rod, rigidly
connected to said opening in pressure-sealed connection therewith,
and having a disconnectible portion to allow for access to said
stop means for adjusting the preload tension of the spring,
said casing comprises a tubular member coextensive and concentric
with said actuating rod, and a hollow base member coaxial with said
tubular member, one end of said base member having threaded
connection with the inner end of said tubular member, the other end
of said base member having threaded connection with said opening in
the housing, and
control means apart from said casing and said pump housing for
governing the pumping cycle, which comprise time controlled valve
means operable from the timer between one valve position which
connects the actuating chamber with a fluid pressure supply for the
duration of the pumping stroke, said supply providing a pressure
high enough to effect the pumping stroke while also overcoming the
resistance of the spring in storing energy therein, and another
valve position which interrupts the pressure supply, while
connecting the pumping chamber to exhaust, and allowing said spring
energy to effect the suction stroke while expelling spent fluid
medium from said actuating chamber.
2. In a single acting pressure fluid actuated diaphragm pump, the
combination which comprises a flanged pump housing member of dished
configuration, provided with a central opening,
a diaphragm facing the hollow of said housing member, concentric
with said central opening, and constituting with said housing
member a pump actuating chamber,
an actuating rod extending from the center of said diaphragm
through said central opening, so that a major portion of its length
is outwardly exposed of said housing,
a compression coil spring encircling said exposed length of the
rod, and confined between said central opening and adjustable stop
means provided on the outer end portion of said rod, said stop
means being operable to adjust a preload tension upon said
spring,
a casing surrounding said exposed length of the rod and comprising
a tubular member coextensive and concentric with said actuating
rod,
means rigidly connecting said casing to said opening in
pressure-sealed relationship therewith, said connecting means
including a hollow base member coaxial with said tubular casing and
having one end in threaded connection with an inner end of said
tubular casing and the other end of said base member having a
threaded connection with said housing, at said central opening
therein, and
said opposite end of said tubular casing having a disconnectible
portion to allow for access to said stop means for adjusting the
same to vary a preload tension of the spring.
3. A pumping system which comprises a diaphragm pump having a pump
housing, a diaphragm dividing the housing into a pumping chamber
having means for pump discharge and for pump intake, and a pump
actuating chamber having an opening substantially concentric with
said diaphragm, said actuating chamber adapted to receive a fluid
pressure medium acting upon the diaphragm to produce the pumping
stroke, and also adapted to be vented during a dwell period
following said pumping stroke, during which period the fluid
pressure supply is interrupted to allow for the pump filling return
stroke of the diaphragm, a casing extending rigidly outwardly from
said opening in pressure-sealed relationship therewith, and an
energy storing spring action device contained in said casing, and
cooperatively associated with said diaphragm through said opening,
and constructed and arranged so as to store energy derived from the
pumping stroke, and thereafter during said dwell period to allow
said stored energy to be expended to exert a pull upon the
diaphragm during said return stroke thereof, means for adjusting
the preload on the spring in said spring action device,
and control means governing the pumping cycle for pressure fluid
supply during the pumping stroke and vacuum supply during the
suction stroke, which control means comprise a first valve position
which connects the actuating chamber with a fluid pressure supply
for the duration of the pumping stroke, said supply providing a
pressure high enough to effect the pumping stroke while also
overcoming the resistance of the spring in storing energy therein,
and a second valve position which interrupts the pressure supply,
while connecting the pumping chamber to a transfer conduit, and a
second timer-controlled valve means interconnected with said first
valve through said transfer conduit, and operable from the timer to
establish one valve position which connects said transfer conduit
to exhaust incident to said second valve position of the first
valve, and to establish another position incident to said second
valve position of said first valve, connecting the actuating
chamber to a vacuum supply for the duration of the return suction
stroke.
4. A pumping system which comprises a diaphragm pump having a pump
housing, a diaphragm dividing the housing into a pumping chamber
having means for pump discharge and for pump intake, and a pump
actuating chamber having an opening substantially concentric with
said diaphragm, said actuating chamber adapted to receive a fluid
pressure medium acting upon the diaphragm to produce the pumping
stroke, and also adapted to be vented during a dwell period
following said pumping stroke, during which period the fluid
pressure supply is interrupted to allow for the pump filling return
stroke of the diaphragm, a casing extending rigidly outwardly from
said opening in pressure-sealed relationship therewith, and an
energy storing spring action device contained in said casing, and
cooperatively associated with said diaphragm through said opening,
and constructed and arranged so as to store energy derived from the
pumping stroke, and thereafter during said dwell period to allow
said stored energy to be expended to exert a pull upon the
diaphragm during said return stroke thereof, and means for
adjusting the preload on the spring in said spring action
device,
and control means governing the pumping cycle, which comprise a
closed pressurized storage and buffer tank, containing a body of a
liquid pressure medium, a reservoir open to the atmosphere
containing another body of said liquid pressure medium, a pump for
continuously supplying said liquid medium to said pressurized
tank,
and a timer-controlled valve operable from the timer between one
valve position connecting the actuating chamber of the pump with
pressurized tank, to allow the pressure in said tank to effect the
pumping stroke, and another valve position connecting said
actuating chamber with air exhaust delivery conduit during the
return suction effected by the stored spring energy, said conduit
delivering the spent liquid into said reservoir.
Description
This invention relates to diaphragm pumps and pumping systems
embodying a diaphragm pump, which are well suited and operationally
reliable for handling sludges and slurries, for example sewage
sludges and metallurgical pulps. These are volumetrically effective
displacement pumps relatively immune to wear and tear by the slurry
solids, and self-priming when installed with a negative suction
head, with their capacity and mode of operation readily adjustable
by the adjustment of the length and/or frequency of the stroke.
Therefore the diaphragm pumps are distinct from rotary pumps such
as centrifugal pumps or Moyno pumps or other rotating pumps which
as a class are subject to wear and tear due to the rotation of
parts, especially in an abrasive environment.
This invention relates more particularly to pressure operated
diaphragm pumps as well as pumping systems embodying a diaphragm
pump, wherein the pumping stroke is effected by fluid pressure
admitted to the opposite side of the diaphragm while the return
stroke may be effected either by gravity filling of the pump
chamber, or by the application of vacuum alternating with the fluid
pressure, acting upon said outer exposed side of the diaphragm.
These pressure operated or non-mechanically actuated pumps again as
a group are distinct from those that are known as the mechanically
driven pumps wherein positive reciprocation of the diaphragm is
effected by a mechanically or positively motivated actuating rod
connected to the diaphragm.
Thus it will be understood that the prior pressure operated
diaphragm pump comprise a pump housing divided by a free floating
diaphragm into a pressure actuating chamber, and a pumping chamber.
A control system including timing devices regulate the admission of
the pressure fluid alone where pump filling under a positive or
gravity suction head is available, or they regulate the admission
of pressure fluid alternating with vacuum where the pump chamber is
required to operate with a negative suction head. The fluid
pressure medium may be air or water, whichever is practical under
given circumstances.
The mechanically or positively actuated diaphragm pumps in turn,
require nothing but a power supply for their operation, but they
suffer from the disadvantage that the diaphragm due to its positive
mechanical connection to a reciprocating drive, is subject to a
combination of high shearing, bending, and tension stresses in the
operation of the pumping cycle. These stresses are aggravated by
the uncushioned reversal of the forces effective on the diaphragm
at the end of the respective strokes of the pumping cycle, which in
turn limits diaphragm life, and limits discharge head capability.
Such stresses then lead to shutdowns and replacements of the
diaphragm when destruction thereof is imminent or has occurred.
Under these conditions, maximum stresses in the diaphragm occur
during the pumping stroke when the actuating rod acting like a
punch upon the central portion of the diaphragm, must push against
the full pumping head. Correspondingly high shearing stresses thus
develop around the two clamping plates that fix the central portion
of the diaphragm to the actuating rod. Lesser stresses develop
during the return or pump filling stroke, for instance with the
pump operating on a suction head that is a fraction of the 34 ft.
maximum lift determined by the atmospheric pressure. A practical
average suction lift frequently required is in the order of 10 to
12 ft., as compared with a pumping head that may be, say, ten times
that much.
The diaphragm pumps of the group that are operated by fluid
pressure, or else by a combination of fluid pressure and vacuum,
acting upon the free floating diaphragm, are stress-compensated in
the sense that they avoid the aforementioned high diaphragm
stresses inherent in the mechanically actuated pumps, thereby
prolonging the life of the diaphragm. However, their operation is
relatively sluggish in negative suction lift applications and their
capacity relatively limited due to the time-consuming character of
the operating cycle which in the case of negative suction lift
operation and air as the pressure medium, comprises (a) admission,
build-up, and maintaining of air pressure to effect the pumping
stroke, (b) venting the air pressure chamber at the end of the
pumping stroke, (c) admission, build-up, and maintaining of vacuum
instead of the air pressure to effect the pump-filling stroke, and
(d) again venting in preparation for the next pumping cycle. This
mode of operation is relatively sluggish especially in the handling
of sludges of higher densities and/or viscosities, although
providing cushioning effects in the operating cycle, that are
lacking in the aforementioned group of mechanically actuated pumps.
To this must be added the cost for providing both the fluid
pressure and the vacuum.
It is a general object of this invention to provide an improved
diaphragm pump that is free from the essential drawbacks of the
aforementioned two groups of diaphragm pumps.
Consequently, it is among the more specific objects to provide a
diaphragm pump which avoids the high diaphragm stresses of the
mechanically actuated pumps; which minimizes wear and tear on the
diaphragm by minimizing the diaphragm stresses throughout the
pumping cycle; which overcomes the sluggishness and capacity
limitations of the pressure-actuated pump, while maintaining the
cushioning effects; and which is economical to operate.
Another object is to provide inexpensive means for converting a
pressure-operated diaphragm pump operating under a gravity suction
head into one adapted for negative suction lift operation, yet
without requiring a vacuum supply.
Still another object is to provide inexpensive means for increasing
the capacity of fluid pressure-actuated diaphragm pumps
irrespective of whether or not they are equipped for gravity head,
or negative suction head operation.
Another object is to provide a diaphragm pump of great versatility,
applicable to a large spectrum of operating conditions and
requirements.
In order to attain the foregoing objectives, this invention
provides a diaphragm pump of the fluid pressure operated type
equipped with a novel auxiliary or booster spring action device
moving the diaphragm in a novel type of pumping cycle. In the
operation of this pumping cycle, a spring means stores energy
derived from the fluid pressure operated pumping stroke, which
energy is subsequently expended in effecting, or assisting in the
return stroke of the diaphragm.
Pre-tension of the spring is adjustable to suit a variety of
operating requirements which may include converting the pump
operation from gravity suction head to negative suction head
operation, and vice versa, or else merely increasing the capacity
or efficiency of the pump.
In a practical embodiment of the invention, the diaphragm is
connected to an actuating rod extending through the wall of the
pump housing in a direction opposite to the delivery side thereof,
and perpendicular to the plane of the diaphragm. The protruding
length of the actuating rod, surrounded by a compression spring, is
fully enclosed in a tubular shell or casing rigidly connected to
the wall of the pump housing, and in air tight sealed relationship
therewith. With this spring action device in the pumping cycle, the
moving force exerted upon the diaphragm is, at most, moderate or
negligible thus minimizing wear and tear on the diaphragm, as will
appear from the following outline of the operating cycle employing
air pressure, which comprises:
1. Pumping - or Delivery Stroke:
Air pressure is admitted to the actuating pump chamber by a power
starting signal from a timer, controlling a solenoid valve. The
power stroke, while pumping against pump discharge head, also
compresses the coil spring causing it to store energy. Air pressure
is shut off by the timer at the end of the power stroke, thereby
immediately releasing the stored energy of the spring, while
venting the actuating chamber.
2. Suction Stroke:
The timer keeps the power shut off for the duration of a dwell
period, allowing the stored energy of the spring to effect the
return or suction stroke of the diaphragm, while at the same time
displacing the residual air or actuating fluid from the actuating
chamber.
3. At the end of the dwell period and of the suction stroke, the
timer again allows air pressure to be admitted for the next pumping
cycle.
The diaphragm stresses are thus minimized, since the forces acting
upon the diaphragm can never exceed the maximum compression force
imposed upon the spring, which in turn need only be great enough to
effect the return or suction stroke.
Additional stress relieving factors are that the stroke reversal
stresses are cushioned in the operation of this pumping cycle, and
that the diaphragm itself is subject to flexure in only one
direction, and not alternatingly between convex and concave, or
between an annular valley and an annular peak.
Specific features lie in details of construction of the booster
spring device.
Other features lie in the manner whereby conventional air
pressure-actuated pumps can be converted into improved pumps
operable in accordance with this invention.
Another feature lies in the provision of means for controlling the
capacity of the pump by way of adjusting the preload on the spring
of the energy-storing device.
Other features lie in timer-controlled pumping systems embodying
this invention.
Other features and advantages will hereinafter appear.
Now referring to the drawings:
FIG. 1 is a vertical sectional view of the timer-controlled
diaphragm pump equipped with the booster spring action device
featuring an air tight encased compression spring surrounding a
diaphragm actuating rod, and cooperating with an air pressure
medium supply.
FIG. 1a is a fragmentary detail view showing a modification of FIG.
1.
FIG. 2 is a reduced vertical side view of the pump of FIG. 1,
showing the compression spring with the casing removed.
FIG. 3 is an exploded view of the pump of FIG. 1, illustrating a
conversion feature for embodying the invention in existing
pumps.
FIGS. 4, 5, 6 and 7 show a pumping system illustrating an operating
cycle of the pump embodying the invention.
FIG. 8 schematically illustrates diaphragm deformation and stresses
in the pump embodying this invention.
FIG. 9 is a schematic view of a pump system equipped with the
energy storing spring action device, operated with water as the
pump actuating pressure medium.
The operation of the diaphragm pump embodying an example of this
invention in FIG. 1, is controlled by the setting of one or more
solenoid actuated valves, which setting in turn is governed by a
timing device or timer sending power signals to the valves. The
timing of the operating cycle is such that a fluid pressure medium
is admitted through one of said valves to the actuating chamber of
the pump at a pressure high enough to execute the pumping stroke of
the diaphragm, thus delivering the contents of the pumping chamber
against the pressure of the pumping head. At the end of this
pumping stroke, the supply of fluid pressure medium is shut off by
the timer, while a vent connection is opened to the actuating
chamber, in preparation for the subsequent return -- or pump
filling stroke.
According to this invention, in case there is available a negative
suction head, the return stroke does not require the application of
a vacuum to the pumping chamber, but is carried out effectively by
a novel spring action device mounted upon the actuating chamber,
and having a mechanical connection to the center of the diaphragm.
The fluid pressure medium is admitted to the actuating chamber at a
pressure sufficiently in excess of the pumping head, as well as in
excess of the pre-tension of the spring means of the spring action
device, whereby the spring means are tensioned in proportion to the
length of the pumping stroke, with a corresponding amount of
mechanical energy thus being stored in the spring.
When the supply of the pressure medium is shut off and the vent is
opened at the end of the pumping stroke, the energy stored in the
tension spring is thereby released, immediately initiating the
return -- or pump filling stroke which simultaneously displaces the
spent fluid pressure medium from the actuating chamber through the
vent connection.
In case there is available a gravity head at the pump intake, the
energy storing spring action device can be oriented towards
accelerating the return stroke action, thereby increasing the
capacity of the pump, especially where there is only a moderate
gravity head available.
Even with vacuum supply available as in an existing timer --
controlled standard pump installation, the spring action device of
this invention is advantageously applicable to aid the vacuum
effect, thereby again accelerating the return stroke and increasing
the pump capacity. On the other hand, in such an instance the
existing vacuum supply may be dispensed with by substituting the
energy storing effect of the spring action device of this
invention, even though continuing the use of the existing timing
and control devices governing the operating cycle of the pump.
Referring to the example embodying the invention in FIG. 1, the
pump in the upright position herein shown has a circular diaphragm
10 marginally confined between an upper part or section 11 and a
lower part or section 12 of a pump housing H, which parts or
sections are detachably connected to each other in pressure tight
relationship. The diaphragm thus divides the pump housing into a
pump chamber 13 at the bottom and an actuating chamber 14 at the
top. The upper housing section 11 has an opening 15 concentric with
the diaphragm. The lower housing section 12 representing the
pumping -- or delivery chamber has a connection 16 communicating in
a usual manner (see FIG. 2) with an intake -- or suction pipe 17
through a check valve 18, as well as with a delivery pipe 19
through a check valve 20.
The upper housing section 11 has a second opening 15a provided for
the purpose of admitting into the actuating chamber a fluid
pressure medium usually air, but where compressed air may be
unavailable, it could be a liquid such as water or it could be
oil.
An actuating rod 21 connected to the center of the diaphragm
extends upwardly through opening 15, a substantial distance D
beyond the top of the pump housing. An elongate substantially
tubular upright casing 22 provides an airtight enclosure for the
upwardly protruding end portion of the actuating rod. The casing
itself comprises a tubular member 23 having a top end closed by a
screw cap 24, and a bottom end rigidly connected to a cup-shaped
base member or nipple 25, as through a thread connection 26. This
cup-shaped base member has a downwardly extending neck portion 27
which in turn is tightly threaded into the corresponding upwardly
extending neck portion 28 of the pump housing. A bushing 29
inserted in the base member may provide loose guidance for the
actuating rod. An annular plate 30 fitted over the bushing presents
the inner bottom face 31 of the casing.
The diaphragm has a suitable connection with the actuating rod 21,
whereby the central portion of the diaphragm is confined tightly
between a pair of pressure plates 21a and 21b of a suitable
diameter d and held in place by a cap nut 21c against a shoulder
21d formed on the actuating rod.
A compression coil spring 32 contained within the casing surrounds
the actuating rod being end wise confined between said bottom face
31 of the casing and an adjustable stop means 33 provided upon the
upper threaded end portion 34 of the rod. This stop means may be
adjusted by using the adjustment nuts 34a and 34b, so as to impose
a suitable pre-tension upon the compression spring, the amount of
such pre-tension on pre-load depending upon a variety of specific
conditions or technical applications of the pump, such as will be
furthermore set forth below. FIG. 2 illustrates how the elongate
part of the casing 22 may be removed from the base member, in order
to expose the pre-tension adjusting means.
A modification of the top end portion of casing 22 comprises a
screw cap 23.sup.a on tubular member 23, provided with an
adjustable stop screw 23.sup.b and lock nut 23.sup.c coaxial with
the actuating rod 21.
FIG. 3 is an exploded view of the pump shown in FIG. 1 above
described, to illustrate the feature of convertability. This means
that a sub-assembly S of parts including the energy storing spring
action device above described, may take the place of the upper part
or housing section of an existing timer-controlled air diaphragm
pump having air pressure -- as well as vacuum supply. This
sub-assembly may in fact include even the existing diaphragm which
can be prepared for the purpose of conversion simply by the
provision therein of a central hole for the actuating rod.
The special function and effect as well as the features and
advantages of the energy storing spring action device will
furthermore appear from the following description of the pump
operating cycle as illustrated in FIGS. 4, 5, 6 and 7.
For this purpose it may be assumed that the pump together with its
operating control system schematically shown in FIG. 4 is one that
has been converted in the manner of FIG. 2 above described. In that
case, the energy-storing device acts to enhance the existing vacuum
effect applied to the actuating chamber during the pump filling or
suction stroke, thereby accelerating the pumping action, and
increasing the capacity of the pump.
The control system schematically shown comprises a pair of rotary
valves V-1 and V-2 motivated by solenoid devices P 1 and P-2
respectively. These solenoid devices in turn receive power signals
from a timing device or timer (not shown) in the pumping cycle
described as follows:
The Pumping -- or Delivery Stroke:
To begin the pumping cycle, with a setting of the valves according
to FIG. 5, and upon a power signal from the timer, compressed air
from a supply pipe 35 is admitted to the actuating chamber 14 of
the pump through valve port 36 of valve V-1 and pipe connection 37.
The air pressure moves the diaphragm in a pumping stroke from an
upper limit position to a lower limit position, thereby delivering
the content of the pumping chamber 13 against the existing pumping
head. The air pressure thus applied through valve V-1 is in excess
of that required by the pumping stroke, the excess being sufficient
to compress the coil spring 32, as well as to overcome an amount of
pre-tension imposed upon the spring by the setting of the stop
means 33. The position of valve V-1 during this stroke closes an
intermediate pipe connection 38 extending between valve V-2 and
valve V-1, while valve V-2 has an exhaust connection 39
communicating through valve port 40 with the intermediate pipe
38.
The Suction - or Pump Filling Stroke:
At the end of the pumping stroke, a power signal from the timer
moves the valve V-1 to the FIG. 6 position, thus shutting off the
air pressure supply while valve V-2 remains unchanged, thus briefly
establishing an exhaust or vent connection through valve V-2, which
equalizes the pressure in the actuating chamber with that of the
atmosphere. The timer thereupon sends a power signal moving the
valve V-2 to the FIG. 7 position, while the position of valve V-1
remains unchanged, thereby establishing a connection between the
actuating chamber 14 and a vacuum supply pipe 41 by way of port 40
of valve V-2. The suction -- or pump filling stroke is initiated
immediately upon shutting of the air supply, due to the release
thereby of the energy stored in the spring during the pumping
stroke. This energy is now expended to sustain the suction stroke,
aided by the vacuum supply, while simultaneously effecting the
evacuation of the actuating chamber. At the end of this suction --
or pump filling stroke, the timer sends power signals for resetting
valves V-1 and V-2 to the initial FIG. 5 position.
It will be understood, however, that the vacuum supply phase can be
omitted from the pumping cycle just described of FIGS. 4 to 7,
simply by omitting the valve V-2 and its accessories, and venting
the actuating chamber of the pump directly from valve V-1, and
further by a suitable resetting of the pretension of the
spring.
The schematic showing of a timer-controlled pump system in FIG. 9
differs from the one shown in FIG. 4, due to the fact that a liquid
is employed as the pump actuating fluid pressure medium instead of
air. Therefore, a diaphragm pump 45 structurally and functionally
corresponding to that of FIG. 1, is connected to a pressure supply
system which comprises a closed pressurized storage -- or buffer
bank 46 which has therein an air pressure cushion 46.sup.a
maintainable, if need be, through a check valve 45.sup.b similar to
an automobile tire valve or the like. A pump 47 continuously
supplies water or other suitable liquid such as oil from a
reservoir 48 which is open to the atmosphere.
In the operating cycle of this system, a solenoid-controlled valve
V-3 having received a power signal from a timer (not shown), is set
with the port 49 allowing liquid from the pressurized tank 46 to be
forced into the actuating chamber 50 of the pump, moving diaphragm
51 downwardly against the pumping head while simultaneously through
actuating rod 52 compressing the spring 53 of the energy-storing
device. At the end of this pump delivery stroke, the timer will
send a power signal to the valve V-3, causing the port 49 (see
dotted line position) to interrupt the supply of the pressure
liquid, while establishing a flow -- or vent connection with the
actuating chamber. This immediately releases the energy stored in
the previously compressed spring, effecting the upward return - or
pump filling stroke that displaces the spent liquid from the
actuating chamber back into the reservoir 48, whereupon the cycle
repeats itself.
From the foregoing it will be seen that the actuating rod is
subjected to pull and not to compression throughout the pumping
cycle. On that basis, it is also seen, from the schematic
illustration in FIG. 8, that in a pump 54 structurally and
functionally corresponding to that of FIG. 1, the flexure of the
diaphragm occurs substantially in only one direction throughout the
pumping cycle, thereby reducing wear and tear on the diaphragm.
Therefore, the three positions A, B and C of the diaphragm shown in
FIG. 8, represent the respective flexures that manifest themselves
during the delivery stroke as well as during the suction -- or pump
filling stroke. The flexures A and B represent the end condition,
and flexure C an intermediate condition of the diaphragm, with the
actuating rod 55 and the spring 56 acting in the manner previously
described.
In connection with these flexures, it should be understood that the
diaphragm in its downward movement under pressure from the fluid
medium admitted through a connection 57 hugs the bottom of the
pumping chamber progressively from the periphery towards the
center, although this condition does not appear fully in FIG. 8 due
to the schematic character thereof. Therefore, the diaphragm in its
downward movement under fluid pressure, evenly displaces pulp or
slurry progressively inwardly towards the outlet connection 44 of
the pumping chamber, which avoids trapping of material between the
diaphragm and the pump housing.
This invention provides means for adjusting the pump capacity by
way of setting the pre-load on the spring of the energy-storing
device, by adjusting the position of the stop means 33 on the
actuating rod. Such adjustments are described as follows:
Capacity Control through Spring Preload Adjustment:
Maximum pumping capacity is achieved by imposing maximum preload
upon the spring, that is without exceeding the design limit or
capability of the spring when it reaches its maximum compression at
the bottom end of the pumping -- or delivery stroke. When a
reduction below maximum is required, this is obtainable by a
corresponding reduction in the preload on the spring by using the
adjustment nuts in stop device 33 (see FIG. 1).
Under negative suction lift conditions, the length of the suction
stroke is determined by the amount of preload imposed upon the
spring, the preload required being proportional to the amount of
suction lift. That is to say, the minimum amount of spring
compression force that will pull the diaphragm to the desired top
limit in the actuating chamber 13 of the pump, is the minimum
preload FM required to provide full volumetric pump capacity per
stroke. A preload on the spring of less than FM and designated as
FR, reduces the length of the stroke, thereby reducing the capacity
per pumping cycle.
During the pumping stroke, an additional compressive force FS is
imposed upon the spring, which is in excess of the preload FM that
exists at the upper limit or beginning of the stroke. This
additional force FS creates the vacuum which moves and accelerates
the fluid mass into the lower pump chamber 14 on the suction
stroke. Increasing the preload force FM by an amount FA produces a
corresponding increase in the amount of force available for said
mass acceleration, thereby increasing the pump filling rate. These
conditions are summarized in the following tabulation.
TABULATION ______________________________________ TOTAL SPRING
COMPRESSION FORCE AT END OF PUMPING STROKE MODE OF OPERATION EFFECT
ON PUMP CAPACITY *DIAPHRAGM STRESSES FOR BOTH SUCTION &
DISCHARGE STROKES ______________________________________ FM+FS Full
suction stroke (average acceleration) Average capacity Nominal
FM+FS+FA Full suction stroke (Increased Acceleration) Above average
capacity Slightly above nominal FR+FS Partial suction stroke Below
average capacity Below nominal
______________________________________ *With diaphragm flexure
occurring substantially in only one direction throughout the
pumping cycle, thereby reducing wear and tear on the diaphragm.
In addition to capacity adjustment with the timer, and the spring
preload adjustment discussed above, there is available a third
variable control factor affecting the capability of the pump,
namely the amount of fluid pressure applied in the actuating
chamber 13 of the pump. That is to say, the higher the pressure,
the greater becomes the capacity. If the fluid pressure is reduced
below an amount that will neutralize the force FM + FS, such a
reduction will cause the pump to operate at a shorter stroke,
thereby reducing the overall capacity of the pump.
By manipulating the control factors, namely Timing, Spring Preload,
and fluid pressure, singly or in combination, the pump capacity can
be varied within the limits of capability of the pump. Also, with
these control factors available, the stroke can be shortened, and
frequency increased, thus dampening out the pulse effect, and
producing a more continuous flow from the pump, when the technical
application of the pump requires that the amplitude of the pump
pulses should be minimized.
As this invention may be embodied in several forms without
departing from the spirit or essential character thereof, the
present embodiment is illustrative and not restrictive. The scope
of the invention is defined by the appended claims rather than by
the description preceding them, and all embodiments which fall
within the meaning and range of equivalency of the claims are,
therefore, intended to be embraced by those claims.
* * * * *