Note: Descriptions are shown in the official language in which they were submitted.
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ELECTRIC MOTOR DRIVEN DIAPHRAGM PUMP
BACKGROUND OF THE INVENTION
This invention relates to an improved diaphragm
pump and, more particularly, to a double acting
diaphragm pump which is operated by an electric motor.
Heretofore, diaphragm pumps have been generally
fluid actuated. Whether the pump is a single or double
acting diaphragm pump, the method of driving the
diaphragm pump has principally been by pneumatic fluid.
Typical of a pneumatically-operated double-acting
diaphragm pump is the pump disclosed in U.S. Patent No.
; ~' 3,791,768 issued February 12, 1974 - Fluid Pump.
In addition to diaphragm pumps that are operated
by pneumatic means, various electrically operated
diaphragm pumps have been proposed and patented.
3~ Typical of such electrically operated diaphragm pumps
15 ~ lfi~ are those disclosed in the following patents:
'S~Pat. No. Invention Issued
2,471,796 Air Pump For Aquarium Aerators 5/31/49
2,463,766 Compressor 3/8/49
2,285,215 Fluid Compressor 6/2/42
` 20 3,286,933 Duplex Chemical Feeding System 11/2/66
3,308,765 Pump Construction 3/14/67
~ ¦ ,3 4,154,559 Electromagnetic Reciprocating Pump 5/15/79
The prior art electrically-operated diaphragm
pumps generally provide an electric motor which
continuously operates to provide power from an output
shaft to drive an eccentric. The eccentric is
connected through a gear train or mechanism to
reciprocate a shaft which reciprocates the operation of
diaphragms. Other prior art uses a solenoid coil to
reciprocate a shaft attached to a diaphragm.
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While such prior art constructions have proven
to be quite useful, there has remained a need for an
improved, electrically operated diaphragm pump,
particularly a double acting diaphragm pump which
provides substantially continuous output from
diaphragms to continuously pump a fluid, particularly a
viscous fluid.
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SUMMARY OF THF INVENTION
Briefly, the present invention comprises a
reciprocating double diaphragm pump operated by a
variable speed reversible direct current electric motor
incorporated within the housing for the pump. The
electric motor includes a rotor which is generally co-
axial with a drive shaft mechanism that is concentric
with the double acting spaced diaphragms of the pump.
The rotor of the motor is operated reversibly in
response to a driver controller and includes an
internal concentric thread cooperative with a lead
screw on the drive shaft. The drive shaft is, in other
words, externally threaded. As the rotor turns, it
drives the lead screw in one direction or the other
depending upon the direction of rotation of the motor
rotor. A driver controller senses the rotation of the
rotor and controls the electrical signal input to the
stator coil associated with the rotor. The opposite
ends of the lead screw drive shaft are enclosed in
bellows at the attachment of the lead screw to the
diaphragm. Reciprocation of the lead screw drive shaft
causes a pumping action due to movement of the
concomitant reciprocation of the diaphragms within the
chambers located at opposite ends of the pump housing.
Thus, it is an object of the invention to
provide an improved diaphragm pump.
It is a further object of the invention to
provide an improved motor driven double acting
diaphragm pump.
Yet another object of the invention is to
provide an improved double acting diaphragm pump
wherein a rotor and lead screw drive shaft are co-axial
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with one another and the lead screw drive shaft is
generally concentric with diaphragms located at each
end of the shaft connected to the shaft.
Yet a further object of the invention is to
provide an improved double acting diaphragm pump
operated by a direct current reversible motor or other
motor which is economical to manufacture and easy to
service and repair.
Yet another object of the invention is to
provide an improved double acting diaphragm pump
operated by motor which eliminates the need for complex
eccentric mechanical arrangements, gear boxes and the
1 ike .
A further obj ect of the invention is to provide
an improved double-acting diaphragm pump which is
driven by an electric motor positioned between the
reciprocating diaphragms within a pump housing.
Yet a further object of the invention is to
provide an improved double acting diaphragm pump
wherein the electric motor which drives the pump is
easily controlled including the speed of
reciprocation, the force imposed upon the reciprocating
diaphragms as well as the length of stroke of the
reciprocating components.
These and other objects, advantages and features
of the invention will be set forth in a detailed
description which follows .
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BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description which follows,
reference will be made to the drawing comprised of the
following figures:
FIGURE 1 is an end elevational view of an
improved double acting motor driven diaphragm pump of
the present invention;
FIGURE 2 is front elevation cross-sectional view
of the pump of FIGURE 1 taken substantially along the
line 2--2.
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DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention is directed to a double-
acting diaphragm pump wherein a pump housing is
provided with spaced, generally parallel, flexible
diaphragms which are each positioned within separate
pump chambers. The diaphragms are designed to
reciprocate within their respective chambers to impart
a continuous pumping action of fluid through the pump.
Thus, as one of the diaphragms is pushed into a chamber
to thereby evacuate that chamber and pump fluid from
that chamber, the second diaphragm withdraws from its
chamber thereby causing fluid to inflow into the
chamber for subsequent pumping on the reverse stroke.
The present invention is directed in particular
to a double-acting diaphragm pump wherein an electric
motor is utilized to effect the reciprocating action of
the diaphragms. That electric motor is positioned
intermediate the diaphragms and more particularly along
a line joining substantially the center of the
respective diaphragms. In a preferred embodiment, the
~ electric motor is a reversible, direct current motor
r which has a fixed stator and a rotor comprised of
permanent magnets. The axis of rotation of the rotor
is coincident with the axis of a lead screw drive shaft
- mechanism which is threadably driven by the rotor.
The lead screw drive shaft mechanism interconnects the
center points of the spaced diaphragms. Motor speed
mày be varied to provide for variable speed of
operation of the lead screw drive shaft mechanism which
reciprocates and drives the diaphragms. The motor is
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-; responsive to solid state electronic motor controls.
The motor and the controls are encapsulated within a
motor housing retained within the housing for the pump.
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Referring, therefore, to the figures there is
illustrated in greater detail a preferred embodiment of
the sub~ect matter of the invention. The pump is
comprised of a pump housing 100 which is fabricated
from a central core or housing 18 and connected
substantially identical in end housings 104 and 106.
The central housing ~8 serves as a housing for a motor
generally shown at 108. The end housings 104 and 106
serve to define diaphragm chambers 10 and 11,
respectively. An inlet 8 connects through an inlet
manifold 114 through inlet ball check valves 12 and 13
to the separate diaphragm chambers 11 and 10. Outlet
ball check valves 1 and 15 connect to an outlet
manifold 116 which, in turn, is connected to an
outlet 16.
Thus, the overall general construction and
: configuration of the double diaphragm pump depicted is
similar pneumatically operated prior art double
diaphragm pumps. There are first and second diaphragms
l and 2 which are connected to one another by a
diaphragm connecting shaft or rod 3. The diaphragms 1
and 2 are retained by diaphragm nuts 4 and 5
cooperative with support washers 6 and 7 that are
~ attached to the diaphragm connecting rod 3 at the
1 25 opposite ends thereof. As the diaphragms 1 and 2 are
driven to the left by the diaphragm connecting rod 3,
suction draws working fluid from the fluid inlet 8
filling the right diaphragm chamber 10 as it flows past
the ball check valve 13. Working fluid is
: 30 simultaneously displaced by the left diaphragm chamber
1 and is forced out of the chamber 11 through the ball
check 14, the manifold 116 and the outlet 16. The
reciprocal operation of the connecting rod 3 effects
the reciprocal movement of the diaphragms 1 and 2 and
.
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2~09361
ball check valves 12, 13, 14 and 15. The diaphragms 1
and 2 include a bead seal 17 where the central housing
18 is connected to the respective end housing 104 or
106 by appropriate locking bolts 118 to thereby effect
a seal of the diaphragms 1 and 2, and prevent leakage
of the fluids between the diaphragm fluid chambers 10
and 11, and the housing 18 for the electric motor 108
or the central housing 18.
In continued operation as described, diaphragms
1 and 2 continued to move to the left until the preset
maximum stroke length is obtained by the rod 3. The
electric motor assembly 108 then reverses the direction
of the diaphragm connecting rod 3 to the right. The
diaphragms 1 and 2 are driven to the right by the
; 15 diaphragm connecting rod 3. Suction pulls the fluid
through the fluid inlet port 8 filling the left
diaphragm chamber 11 as it flows pass the ball check
12. Fluid is simultaneously displaced by the right
diaphragm 2 from the chamber 10. The right diaphragm 2
is sustained by the plate washer 6 as fluid is forced
to the right from the chamber 10 past the ball check
valve 15. Simultaneous with this, the ball check balls
13 and 14 are seated. Fluid then flows through the
` outlet port 16. Again the bead seal 17 prevents
` 25 leakage of fluid from the diaphragm fluid chambers 10
~ and 11 into electric motor housing 18. The diaphragms
`~ 1 and 2 continue to the right until the preset maximum
stroke is obtained and the sequence is then reversed.
The electric motor 108 retained within the
housing 18 is a direct current, brushless type,
reversible motor. The motor is comprised of an
.,~
armature l9A with armature winding 19 defining a
stator that is generally concentric with an axis 120
; associated with the rod 3 and the center point of the
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diaphragms 1 and 2. Rotor constitutes a permanent
magnet 20 attached to the outside of a rotor spindle at
21. The spindle 21 i5 mounted for rotational movement
about the axis 120 on spaced bearings or bushings 23,
24 supported on plates 25, 26 in the housing 18. In
this manner the rotor spindle 21 is rotatable about the
axis 120 in response to DC current signals through the
windings 19. The DC current generated in the motor
armature circuit is commutated with position sensors 22
retained within the stator l9A. The entire assemblage
is controlled by a motor driver controller 29 as shown
in FI~,URE 1.
The rotor spindle 21 is positioned within the
motor armature windings 19 and as previously indicated
and supported each end by bearing 23 and 24. Affixed -
to the outside of the spindle 21 are permanent magnets
20 which supply the magnetic flux for the motors field
circuitry. The motor bearings 23 and 24 are encased
- within separate housings or plates 25 and 26 and
retained by spring retainers 27 and 28 within the motor
housing 18. The bearing housings 25 and 26 restrict
play of the spindle 21 and absorb axial torque
~ generated by the reciprocating device and radial loads
`~ produced by the motor. The rotor spindle 21 has a
secondary function as the drive member of the
reciprocating device for the pumping action.
Reciprocation is effected by driving the rod 3
which is axially driven member moving in the direction
of axis 120. The rod 3 is driven by rotating drive
; 30 member; namely, the rotor spindle 21. Thus the rotor
spindle 21 being the drive member and the diaphragm
connecting rod 3 being the driven member, they are
cooperative with one another as described.
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The rod 3 is a one piece construction having an
outer or extended thread cooperative with the internal
matching threads of spindle 21. The rod 3 is connected
at its opposite ends to the double diaphragm 1 and 2.
S The rod 3 as it is driven will move to the right or the
left in FIGURE 2. As it moves to the left the left
diaphragm 1 is displacing a volume of working fluid
from the left of the diaphragm chamber 11 and
simultaneously the volume of the right diaphragm
chamber 10 is being expanded to provide suction in that
chamber 10 to fill that chamber 10. As the rod moves
to the right, the right diaphragm 2 displaces a volume
of working fluid in the chamber 10 simultaneously
providing suction in the left diaphragm chamber 11
thereby filling that chamber 11.
The rod 3 changes axial direction by reversing
the rotational direction of the drive member or rotor
spindle 21. The direction of the drive member or rotor
spindle 21 is regulated by the controller 29. That is,
a controller 29 which is typical of such types of
~` devices known in the art is utilized to sense a~d
~` control the number of revolutions of the rotor 21 and
the speed of those revolutions. The controller thus
automatically controls the number of revolutions of the
rotor spindle 21 and automatically reverses the
direction of the rotor spindle 21 when a preset number
of revolutions or cycles are counted by the controller
. 29. This number of rotations is adjustable to thereby
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;~ . control the length of stroke of the rod 3. The ~.
duration of each stroke is also controllable by
- controlling the speed of rotation of the rotor 21.
This, in turn, controls the pumping speed in cycles per
minute. Additionally, as the fluid becomes more
viscous or is originally highly viscous, the force
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applied to the diaphragm to the rotor spindle 21 will
cause the rotor spindle 21 to slow. Motor current then
increases. When the motor current reaches a maximum
preset current, the motor controls will stop the motor
and apply a brake. Excess current can then be
dissipated through a transistor driver thereby
eliminating motor damage.
In other words, the controller 29 continuously
evaluates motor current and other operating
characteristics to control the output by the pump as
well as to control the integrity of or protect the
motor. In review the rotor spindle 21 includes an
internal passage which is threaded to co-act with the
external threads of the rod 3. The internal passage of
spindle 21 may be threaded through the entire length
thereof in order to provide a more uniform driving
force between the rod and the rotor. However, it
should be noted that by threading the entire internal
passage of the rotor spindle 21, friction may build up
due to the interaction between the rod 3 and rotor 21.
It should also be noted that the number of threads per
inch, the pitch and the design of threads for the rod 3
and rotor 21 may be varied in order to vary the
mechanical advantage associated with operation of the
rotor spindle 21 and the rod. Note also that the rod 3
may include a reversible thread thereby enabling
continuous operation in a single rotational sense of
the rotor 21 in order to effect reciprocal movement of
the rod 3 and pumping action.
The housing 18 is preferably an injected molded
thermoplastic which encapsulates the motor armature
; windings 19 in a position sensor 22. The motor housing
18 also retains the rotor bearing housings 25 and 26
which are secured by the spring retainers 30 and 31.
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The spring retainers 30 and 31 also secure a
retractable bellows 9 which fits over the opposite ends
of the rod 3 and connects to plates 6 and 7 to prevent
contamination from the entering the electric motor or
interfering with the threads, that collect between the
rod 3 and rotor 21. The motor housing 18 may also
include passages 32 and 33 at the bottom of the housing
18 that allow any working fluid which escapes from the
diaphragm chambers 10 and 11 to exit in the event of a
diaphragm failure. This prevents flooding of the
electric motor or any internal damage thereto. The
motor housing 18 also accommodates the bead seal and -
the is designed to provide for a region into which the
diaphragms 1 and 2 may move during the reciprocal
~; 15 movement of the rod 3.
Of course it i8 possible to vary the
construction of the invention as described. For
; example, the cooperative rod and rotor assembly may be
utilized in combination with a single diaphragm chamber
` 20 with either a reciprocal DC motor or other types of
~ motors. The rod 3 may alternatively have a reversible ~ -
` ~ thread thereon. More than two diaphragms 1 and 2 are
positively driven in both directions by the described
mechanism. Also diaphragms need not be used. A
piston pump mechanism, may, for example be used as
' could other types of pump mechanisms. Thus the
invention is to be limited only by the following claims
and their equivalents.
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