Pumps – Condition responsive control of pump drive motor – By control of electric or magnetic drive motor
Reexamination Certificate
2001-07-17
2003-08-19
Tyler, Cheryl J. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
By control of electric or magnetic drive motor
C417S044200
Reexamination Certificate
active
06607360
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
The present invention relates in general to pumps for pumping liquid, and in particular to a constant-pressure pump controller system for maintaining a substantially uniform discharge pressure of liquid output from the pump generally irrespective of the number of open downstream outlets drawing such liquid delivered by the pump. Various liquid dispensing systems rely upon one or more pumps to accomplish liquid delivery at a plurality of sites, with many such systems delivering water or water-based liquid for a myriad of uses. Examples of such applications include motor-home water systems, spray systems such as car-wash wands, carpet-cleaning applicators, spray-mist cooling units, auto-service coolant-change reservoirs, and/or various pumps such as transmission oil filter pumps, water pressure booster pumps, carbonator pump, foam application pumps, road compactor spray pumps, street sweeper post-suppressions pumps, and the like. In addition to the delivery of water-containing products, other liquids such as chemicals, fuels, beverages, etc. may be supplied to an end-use site by utilization of a pump.
While certain liquid delivery requirements involve transfer thereof to only one location and therefore involve only a single downstream opening for liquid flow, many systems have a plurality of downstream openings available for simultaneous flow supply at a number of sites. One example of such a system is that found in many well-equipped motor homes that include kitchen and bathroom sink faucets, a shower and toilet, and possibly an outside faucet. When multiple liquid outlets are served simultaneously, as where two or more of the above-exemplified facilities are calling for water, a significant pressure drop automatically occurs at each such outlet since a traditional pump does not change operating parameters to increase delivery pressure. Because of customer dissatisfaction with such conditions, relatively expensive pressure sensors have been developed to adjust pump-motor speed in relation to pressure demand. These prior-art sensors generally include complex piezoresistive regulators operable in conjunction with elaborate built-in amplifiers and intricate temperature compensation networks to permit pump-motor speed control. However, the complexity of such devices, coupled with their expense, many times fails to provide a practical long-term solution over the many potential installations that can beneficially impact users.
In view of such deficiencies, it is apparent that a need is present for a relatively non-complicated pump controller system that can maintain pressure throughout a liquid delivery network at a reasonable cost and over a reasonable period of time without breakdown. In accord therewith, a primary object of the present invention is to provide a pump controller system that continually senses the pressure of liquid moving therefrom and correspondingly adjusting the speed of the pump motor to reflect pressure variations as they occur.
Another object of the present invention is to provide a pump controller system that employs the Hall effect in modifying voltage to achieve regulation of pump-motor speed.
Yet another object of the present invention is to provide a pump controller system wherein pressure value can be changed to correspond with pressure need for any particular application.
These and other objects of the present invention will become apparent throughout the application which now follows.
BRIEF SUMMARY OF THE INVENTION
The present invention is a constant-pressure pump controller system for maintaining a substantially uniform discharge pressure of liquid output from a pump operated by an electric motor and where liquid is to be delivered to a plurality of simultaneously-operating downstream outlets. The system comprises a pressure transducer for sensing discharge pressure from the pump, and includes a housing with an interior chamber, an opening to the chamber, and a flexible seal covering the opening to the chamber. A piston, which is longitudinally movable toward and away from the flexible seal and biased with a pressure member toward the flexible seal, is disposed in the chamber and bears a magnet for Hall effect interaction. To accomplish Hall effect sensing, an electric current carrier is situated to interact with the magnet for production of Hall voltage which is monitored by a voltage sensor in communication with a controller that regulates motor speed through pulse width modulation in response to the voltage value according to proportional integral derivative methodology. Finally, a pump input voltage sensor and regulator maintain a constant voltage output to the pump should voltage input be variable.
As is recognized, the Hall effect develops a transverse electric field in material carrying an electric current and positioned in a magnetic field perpendicular to the current. Depending upon passing-liquid pressure on the flexible seal in the present invention and therefore the axial movement and resulting position of the magnet-bearing piston, the linear displacement of the piston and thus the magnetic field in relation to the current provides a variable voltage signal for the controller to accelerate and/or decelerate the pump motor in direct response to piston movement and, thereby, indirect response to liquid pressure. This employment of the Hall effect provides maintenance of pressure of liquid flow from a plurality of downstream outlets that are simultaneously opened, yet achieves a relatively simple and cost effective manner for attaining such pressure maintenance.
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Aquatec Water Systems: “Aquajet RV Series”, webpage dated Oct. 29, 2001, 2 pages.
ITT Industries Products List, webpage dated Oct. 29, 2001, 8 pages.
ITT Industries Flojet
Stetina Brunda Garred & Brucker
Tyler Cheryl J.
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