Note: Descriptions are shown in the official language in which they were submitted.
`D'
2~44~
"Express MaiL Pos~_L~fice to Addressee~' service under 37 CFR 1.10 on the datc indicated above and
is ~ resse ~ o~ ~ Commi,ssif~er of Patents and Trademarks, ~ashington, D.C. 20231
/ca~. f~ ~ ,~ 1 1 / 1 r~ /P~ 9
Roger ~ Erickson
6770-1
2 Patent
4 CONSTANT OUTPUT PUMP
S~ecification
This application is a divisional application of
parent application Serial No. 07/320,227, filed on March 7,
1989. This invention relates to pumping systems and more
particularly to a volumetric pump that will always pump at
a preselected constant output rate of liquid or slurry
regardless of the amount of head pressure it must pump
against.
14
Background of the Invention
.,
In conventional air operated or liquid operated
diaphragm pumps available heretofore, the output volume was
set by the quantity and pressure of the fluid driving
source, either liquid or air. Once this output volume was
set, it remained relatively steady as long as the head
pressure that the pump was discharging against remained the
2 same. However, if or when the head pressure changed,
either increasing or decreasing, the output volume of the
pump also changed. This inherent characteristic of
diaphragm pumps previously available presented a serious
26 disadvantage for systems or applications wherein a constant
output volume from the dispensing pump per unit time was
28 required.
29
3 It is therefore a general object of the present
invention to solve this problem by providing a diaphragm
or a double piston pump system that makes it possible to
pump a constant output volume regardless of the head
pressure changes the pump must discharge against.
36 Another object of the invention is to provide a
volumetric or mete~ing pump that can continuously pump a
38
h9~`., . . . . ~ :
~ ' " : ' ' ,,., ' . :
Z~ 4~
predetermined constant amount of particulate material in
slurry form without being damaged or excessively worn
3 internally by the slurry and without any internal pump
4 slippage.
6 Summary of the Invention
7 In accordance with the principles of the
8 invention a volumetric pump is provided which will provide
9 a constant output despite the resistance head which it has
to pump against. The pump comprises a pair of pump housings
11 each having a piston or a flexible diaphragm situated
12 within its housing. The two pistons or diaphragms are
13 connected by a rigid shaft or link supported by a bearing
14 means between the housings. The two pump housings have an
inlet conduit and an outlet conduit. The inlet conduit is
16 connected to a liquid or slurry supply vessel at one end
17 and to one of each of a pair of check valves at its other
18 end. The outlet conduit is connected at one end to another
19 pair of check valves and to a using receiver of fluid or
slurry (e.g. a filter or elevated tank) at its other end.
21 One of each pair of check valves is connected together by
22 an intermediate conduit and each intermediate conduit is
23 connected to one housing on one side of the internal
24 diaphragm. The two pump housings are also connected to an
air pressure source through a control valve which is
26 connected and controlled by a timer or programmable
27 controller-
28
29 When in use, for example, in a filter system, the
air pressure source can be regulated to move the diaphragms
31 within both housings first in one direction and then in
32 another direction. On movement in one direction, a charge
33 of liquid or slurry is drawn into one pump housing and is
34 ejected from the other pump housing. Under control by the
timer and the control valve, the action is reversed for the
36 two pump housings upon movement of the shaft and its
37 connected diagrams in the opposite direction. Thus, with38
2~1~44~
1 each linear stroke, that is, a full travel of the
2 connecting shaft in one direction, a predetermined charge
3 of fluid or slurry is ejected through the pump outlet, and
4 this occurs despite the level of back pressure at its
outlet. Thus, when used for a filter system, the
6 volumetric pump according to the invention enables a
7 predetermined amount of filter aid to be supplied to a
8 plate type filter despite the level of pressure buildup due
9 to dirt within the filter chambers. By varying the setting
on the timer control, the precise amount of filter aid
11 dispensed by the volumetric pump per unit time can be
12 preselected and maintained continuously during each filter
13 run or cycle.
14
The steady output volume of my pump is so
16 accurate and remains so constant that thi~ pump can be
17 referred to as a zero slip, constant-output, volumetric
18 positive displacement pump.
19
Other objects, advantages and features of the
21 invention will become apparent from the following detailed
22 description of one embodiment thereof presented in
23 conjunction with the accompanying drawings.
24
Brief Description of the Drawing
26 Fig. 1 is a diagrammatic view of a filter system
27 utilizing a volumetric pump embodying principles of the
28 present invention.
29
Fig. 2 is a more detailed and partially
31 diagrammatic view in section of the diaphragm type of
32 volumetric pump shown in Fig. 1 using a single timer.
33
34 Fig. 3 is a diagrammatic view of an alternate
piston form of volumetric pump according to the invention.
36
37
3a
~, ~, ' ' , ' .' ' ' ' ' ' ' ` '
2~ 144$
1 Detailed Description of Embodiment
2 With reference to the drawing, Fig. 1 is a
3 diagrammatic layout of a typical filtering system 10 which
4 utilizes a volumetric pump 12 embodying principles of the
present invention. In the filtering system shown, which
6 may be used, for example, for cleaning oil in a can-forming
7 plant, or coolant used in an aluminum or steel rolling
8 mill, or for any of several other industrial uses, the oil
9 or liquid to be filtered is pumped from a holding tank 11
by a positive displacement pump 13 through a valve 14 in an
11 inlet line 16 to a filter 18 which as shown, may be of the
12 horizontal plate type. In such a filter, as described in
13 my U.S. Patent No. 3,608,734, the filter plates 20 are
14 arranged in a vertical stack and when pressed together they
form a receiving chamber between each pair of plates for
16 the liquid to be filtered and a collecting chamber on the
17 opposite side of each plate for the clean, filtered liquid.
18 The collecting chambers are connected in parallel to an
19 outlet manifold 22 that is connected through a valve 24 to
a clean liquid tank 25. A layer of filter media (e.g.
21 paper) is provided at the bottom of each receiving chamber
22 through which the liquid to be filtered must pass during
23 the filtering process. In order to build up a filtering
24 cake covering the filter media, which is necessary to
provide adequate filtering efficiency, a so-called "body
26 feed~ of particulate filtering material such as
27 diatomaceous earth must be supplied to the flow of liquid
28 filtrate in the inlet line 16. Moreover, the body feed
29 material must be supplied at a constant rate despite back
pressure buildup within the filter, so that the filter cake
31 builds up evenly on the filter media. In the present
32 invention, this body feed flow is controlled with precision
33 by the volumetric pump 12.
34
While the present invention may be applied for
36 use with other types of filters, such as tube filters or
37 screen filters which use a body feed or filter aid to build
38
-, ::~
~': ~ ',',, ': , ', '....... ` :
20~1~4~
an internal cake, the plate type filter 18 is shown for
2 purposes of illustration. The volumetric pump 12 may also
3 be used for other applications where a preselected constant
4 output quantity for each stroke must be maintained during
5 pump operation.
7 As shown in Fig. 1, the pump 12 has an inlet line
8 26 connected through a valve 28 to a body feed tank 30 that
9 contains a supply of body feed material in slurry form. An
10 outlet conduit 32 from the pump 12 is connected directly to
11 the inlet line 16 to the filter. The pump 12 operates, as
12 described below, to dispense, at a constant Ilow rate, a
13 desired or predetermined amount of body feed to the filter
14 18 despite any pressure variations that occur within the
15 filter due to a buildup of dirt therein during a typical
16 filter cycle.
17
18 Turning to Fig. 2, the volumetric pump 12
19 according to the invention comprises a pair of housings 34
20 and 36 each having the same size and shape and mounted on
21 a suitable frame support base 38. Each housing is
22 generally circular and formed by a pair of convex wall
23 members that are connected together at their adjoining
24 circular edges. Within the housings, between the opposite
25 wall members of each, are movable members such as flexible
26 diaphragms 40 and 42, respectively. These diaphragms are
27 connected together at their centers by a straight, rigid
28 link 44 so that the diaphragms move together from side to
29 side, and are always in the same relative positions within
30 their respective housings. The link 44 is supported within
31 a bearing housing 45 that interconnects and supports the
32 pump housings 34 and 36.
33 -
34 The inlet feed line 26 from the body feed slurry
35 supply tank 30 is connected to a "tee" connection 46 that
36 furnishes body feed slurry equally through a pair of pipes ;
37 48, 49 to a pair of inlet ball check valves 50 and 52. The
38
,,~,:; ~.. , : . . . . . . .
-
2~ 4~
l valve 50 is connected by a fluid line 54 to an outlet ball
2 check valve 56, and the valve 52 is connected by a fluid
3 line 58 to an outlet ball check valve 60. The outlet check
4 valves 56 and 60 are connected by outlet lines 61, 62 to
5 the main outlet conduit 32 which supplies body feed slurry
6 to the filter 18.
8 A first air line 66 is connected to the pump
9 housing 34 on one air-only side of its diaphragm 40, and a
lO second air line 68 is connected to the other pump housing
ll 36 at the air-only side of its diaphragm. These air lines
12 66 and 68 are connected to two outlet ports "1" and "2"
13 respectively of a 4-way solenoid valve 70. This valve is
14 supplied with plant air from a suitable source ~not shown)
15 at a constant pressure that is always well above that of
16 the filter back pressure (e.g. 80 psi) through a standard
17 air filter-regulator 72, a lubricator 74 and a needle valve
18 76 in a conduit 77.
19 :'
As shown in Fig. 2, the four-way solenoid valve
21 70 has outlet ports "1" and "2", an inlet port "3"
22 connected to the air pressure supply conduit and an exhaust
23 port "x". Within the valve is a two-position rotor that is
24 moved by a solenoid. In one position, the cylinder
2S provides a passage between the inlet port and outlet
26 port "1" while outlet port "2" is connected to the exhaust ~ ~-
27 port. In this position, air flows in line 66 to pump
28 housing 34 to force its diaphragm to eject slurry through
29 conduit 61, and simultaneously air flows from pump housing
30 36 through line 68 to port "2" and through the internal
31 valve cylinder to the exhaust port of the valve. When the
32 solenoid moves the valve cylinder to its alternate or
33 second position, the inlet port is connected to outlet
34 port "2" while outlet port "1" is now connected to the
35 exhaust port. Thus, the flow of air is now furnished
36 through port "2" of the valve to pump housing 36 through
37 line 68 and simultaneously through line 66 to valve
38
2~1~44~
1 port "1" and then out the exhaust port "x".
3 The solenoid valve 70 may be actuated back and
4 forth between its first and second positions in a
preselected manner or rate by a simple single pole timer
6 78 which is of the type which is commercially available.
7 This timer has an on-off switch 80 connected by a lead 81
8 to a suitable power source so that its time of operation
9 can be set to any preselected time period.
11 In a typical operation of the volumetric pump 12,
12 as used with the filter system of Fig. 1, for example, the
13 body feed slurry from the supply tank 30 flows through line
14 26 through the open check valves 50 and 52 and into one
side of each of the pump housings 34 and 36 as shown in
16 Fig. 2. The timer 78 controls the solenoid valve 70 so
17 that fluid or air pressure for driving the pump is supplied
18 first to one pump housing and then to the other pump
19 housing. The pressure of the driving fluid is always
considerable higher than the head pressure which the pump
21 must work against. For example, when used for a filter
22 system wherein the filter back pressure may be around 80
23 psi, air pressure at a level of around 100 psi is adequate
24 for operating the pump on a constant output basis. As
pressurized air enters each housing on one side of the
26 diaphragm therein, the latter is forced from one side of
27 the housing to the other side. Since the diaphragms 40 and
28 42 for the two housings are connected by link 44, both
29 diaphragms move together. One diaphragm always moves
against a portion of the housing chamber which contains the
31 charge of slurry that was supplied from the slurry supply
32 tank 30 on the previous stroke. Now, as the diaphragm
33 moves against the housing chamber containing slurry, the
34 slurry is forced out of the pump through a ball check valve
56 or 60 and through the common outlet line 32 to the main
36 inlet feed conduit ~6 to the filter 18. Simultaneously a
37 charge of slurry is drawn into the other pump housing from
38
` 7
-~' 20~144~
1 the supply tank and is ready to be expelled during the
2 reverse movement of the diaphragm on the next cycle. The
3 air pressure supplied to the pump is always sufficient to
4 complete a pump stroke in one direction within the time
period set for the timer.
7 Thus, depending on the timing of the strokes for
8 the pump 12, as controlled by the body feed timer 78, it
9 will always take in and pump out an equal amount of liquid
or slurry on each stroke or cycle regardless of the head
11 pressure of the back pressure or head that it must pump
12 against. In a filter system such as shown in Fig. 1, this
13 is highly important because it assures a positive and
14 continually equal ratio of slurry and thus of filter media
such as diatomaceous earth to the dirt load within the
16 filter chamberS- The cake buildup within the filter
17 chambers will thus be more uniform and will remain porous
18 and unplugged for a longer time, and therefore the filter
19 runs between cleaning periods can be longer. This enables
filter operation to be more efficient both in labor costs
21 and filter media consumption.
22
23 In a somewhat modified form shown diagrammatic-
24 ally in Fig. 3, a pump 12A may be provided wherein, in lieu
of the diaphragms 40 and 42 of pump 12, the movable members
26 are provided in the form of rigid piston heads 40A and 42A
27 connected by a link 44A. The piston heads are movable
28 within a cylindrical housing 84 having an internal barrier
29 86 which forms a pair of chambers 34A and 36A. In an
arrangement similar to the pump 12, the pump 12A has an
31 inlet line 26A from a liquid supply to a first pair of
32 check valves 50A and 52A connected to the chambers 34A and
33 36A on one side of the piston heads. Similarly, a second
34 pair of chech valves 56A and 60A from the air source 71 are
connected to pump chambers but on the other side of the
36 piston heads. Air lines from the pump housing are
37 connected to the parts designated "1" and "2" on a 4-way
38
~` 2~1~441
1 solenoid valve 70 which is the same as used with the
2 diaphragm version of the pump 12. As previously described,
3 the solenoid valve 70 is controlled in its operation by a
4 timer 78 and the mode of operation is the same as for the
diaphragm pump 12.
7 Although the structure described for either
8 embodiment of my volumetric pump according to the invention
9 is relatively simple, its performance in providing a
preselected output flow of liquid despite varying back
11 pressure or output head can be maintained with precision
12 and reliability, a feature that is highly desireable for
13 many applications.
14
To those skilled in the art to which this
16 invention relates, many changes in construction and widely
17 differing embodiments and applications of the invention
18 will suggest themselves without departing from the spirit
19 and scope of the invention. The disclosures and the
description herein are purely illustrative and are not
21 intended to be in any sense limiting.
22
23 I claim:
24
26
27
28
29
31
32
33
34
36
37
38
: ,
::,
