Pump control and method of operating same

Details Pump control and method of operating same Pump control and method of operating same

1998-10-13

2001-01-16

Walberg, Teresa (Department: 3742)

Pumps

Condition responsive control of pump drive motor

By control of electric or magnetic drive motor

Reexamination Certificate

active

06174136

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to pumps, and more particularly to a method and apparatus for controlling a pump.
BACKGROUND OF THE INVENTION
Often, it is necessary in an industrial or other process to inject a measured quantity of a flowable material into a further stream of material or a vessel. Metering pumps have been developed for this purpose and may be either electrically or hydraulically actuated. Conventionally, an electromagnetic metering pump utilizes a linear solenoid which is provided half-wave or full-wave rectified pulses to move a diaphragm mechanically linked to an armature of the solenoid.
FIGS. 1 and 2
illustrate a conventional control strategy for an electromagnetic metering pump pumping against ten bar and five bar force levels, respectively. In the conventional electromagnetic metering pump, the solenoid is electrically powered at a sufficient level to provide a pumping force at maximum air gap (i.e., zero stroke) which will meet or exceed the maximum pumping force expected to be encountered. The electric power is also delivered at maximum power level at all other stroke positions, resulting in a wasting of force and energy and development of heat. The heat that is generated typically results in the need for components that can tolerate same, such as metal enclosures and other metal parts and/or larger solenoids with more copper windings. In addition, the extra forces applied to the armature result in the need for relatively heaver return springs and components to counteract residual magnetism and allow the armature to return in time for the pump diaphragm to do suction work. Still further, sound levels are increased owing to the banging of the armature at the end of the stroke when pumping against lower force levels, and further due to the striking of the armature against a stroke adjustment stop at the end of each suction stroke under the influence of the heavy return spring. Service life is typically short owing to the mechanical stresses that are encountered.
In an effort to overcome these problems, a different control methodology has been implemented which has been graphically illustrated in
FIGS. 3 and 4
. In
FIG. 3
, the solenoid is energized by a pulse train consisting of full-wave rectified sine waves followed by half waves. This control methodology allows the pump to be more efficient, thereby permitting larger capacity models to be completely housed in corrosion resistant plastic owing to the lower levels of heat that are produced.
FIG. 4
illustrates yet another modification wherein the ratio of half-wave to full-wave pulses is adjustable so that a user can reduce power if lower pressures are encountered. One can see by an inspection of
FIGS. 3 and 4
that wasted force and energy (and thus heat) are reduced as compared with the conventional technology illustrated in
FIGS. 1 and 2
. However, even with these significant advancements in control methodology, it would be desirable to further reduce the wasting of force and energy in the operation of the pump.
SUMMARY OF THE INVENTION
In accordance with the present invention, a control for a pump and a method of operating same results in a substantial reduction in the amount of wasted force and energy as well as a substantial reduction in the amount of heat produced thereby.
More particularly, in accordance with one aspect of the present invention, a control for a pump having a movable pump element includes a sensor for detecting an operational characteristic of the pump and means responsive to the sensor for controlling movement of the pump element based on the detected operational characteristic.
Preferably, the sensor comprises a position sensor which senses pump element position. Also preferably, the pump element comprises a coil and an armature. The controlling means may include means for modulating electrical power delivered to the coil. In addition, the modulating means may be responsive to pump element velocity.
In accordance with another embodiment, the sensor comprises at least one pressure transducer which senses a pressure differential.
In alternative embodiments, the pump may comprise an electromagnetic metering pump, a lost motion hydraulic metering pump or a variable amplitude hydraulic metering pump.
In accordance with a further aspect of the present invention, a control for an electromagnetic metering pump having a coil, a movable armature and a diaphragm coupled to the movable armature comprises a sensor for detecting an operational characteristic of the metering pump and a driver circuit coupled to the coil and supplying electrical power thereto. Means are coupled between the sensor and the driver circuit for controlling the driver circuit such that electrical power is delivered to the coil in dependance upon a load exposed to the diaphragm.
In accordance with yet another aspect of the present invention, a control for an electromagnetic metering pump having a coil, a movable armature and a diaphragm coupled to the movable armature includes a sensor for detecting armature position and a driver circuit coupled to the coil and delivering electrical power thereto. A programmed processor is responsive to the sensor for controlling the driver circuit such that electrical power is delivered to the coil in dependence upon the position of the armature.
In accordance with yet another aspect of the present invention, a method of controlling of pump having a coil, an armature movable within a range of positions and a pumping element coupled to the armature comprises the steps of detecting the position of the armature and providing electric power to the coil based on the position of the armature.


REFERENCES:
patent: 3602246 (1971-08-01), Hettinger et al.
patent: 3715174 (1973-02-01), Davis et al.
patent: 3723840 (1973-03-01), Opal et al.
patent: 3855515 (1974-12-01), Hutchins, Jr.
patent: 3984315 (1976-10-01), Ernst et al.
patent: 4147824 (1979-04-01), Dettmann et al.
patent: 4195662 (1980-04-01), Gottel
patent: 4285497 (1981-08-01), Guttel
patent: 4291358 (1981-09-01), Dettmann et al.
patent: 4473338 (1984-09-01), Garmong
patent: 4523902 (1985-06-01), Wally
patent: 4534539 (1985-08-01), Dettmann
patent: 4578626 (1986-03-01), Richter
patent: 4661751 (1987-04-01), Werner
patent: 4718824 (1988-01-01), Cholet et al.
patent: 4811624 (1989-03-01), Fritsch
patent: 4839571 (1989-06-01), Farnham et al.
patent: 4841404 (1989-06-01), Marshall et al.
patent: 4966528 (1990-10-01), Henkel et al.
patent: 4994984 (1991-02-01), Massimo
patent: 5013990 (1991-05-01), Weber
patent: 5015153 (1991-05-01), Uesugi et al.
patent: 5040567 (1991-08-01), Nestler et al.
patent: 5054522 (1991-10-01), Kowanz et al.
patent: 5056036 (1991-10-01), VanBork
patent: 5096643 (1992-03-01), Kowanz et al.
patent: 5120199 (1992-06-01), Youngs et al.
patent: 5141402 (1992-08-01), Bloomquist et al.
patent: 5204595 (1993-04-01), Opal et al.
patent: 5249932 (1993-10-01), Van Bork
patent: 5260175 (1993-11-01), Kowanz et al.
patent: 5269659 (1993-12-01), Hampton et al.
patent: 5372482 (1994-12-01), London et al.
patent: 5543108 (1996-08-01), Bacher et al.
patent: 5545012 (1996-08-01), Anastos et al.
patent: 5549456 (1996-08-01), Burrill et al.
patent: 5551664 (1996-09-01), Boke
patent: 5641270 (1997-06-01), Sagourakes et al.
patent: 5650709 (1997-07-01), Rotunda et al.
patent: 5653422 (1997-08-01), Pieloth et al.
patent: 5711346 (1998-01-01), Pieloth et al.
patent: 5718567 (1998-02-01), Rapp et al.
patent: 5746079 (1998-05-01), Hettinger et al.
patent: 5762097 (1998-06-01), Hettinger et al.
patent: 5779218 (1998-07-01), Kowanz
patent: 42 30 662 (1991-09-01), None
patent: 0 294 858 (1988-12-01), None
patent: 0 483 447 (1992-05-01), None
patent: 1 567 041 (1980-05-01), None
patent: 2108212 (1983-05-01), None
International Search Report, PCT/US99/23136, May 24, 2000.
Product Brochure “Metering Pumps”, LMI Milton Roy, Jun. 1998.
Product Brochure “Metering Pumps and Accessories” created in Oct. 1992 for Liquid Metronics Division of Milton Roy.

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