PRESSURE REGULATED ELECTRIC PUMP
 Inventors: Jeffrey D. Bert, Richmond, Va.;
Christopher L. Strong, Boulder, Colo.
 Assignee: Binks Manufacturing Company, Franklin Park, HI.
 Appl. No.: 521,472
 Filed: Aug. 30,1995
 IntCl.6 F04B 49/06
 U.S. CI 417/44.2; 417/415; 74/424.8 C
 Field of Search 417/2, 44.2, 53,
417/415, 534. 536, 568, 362; 92/3, 31, 137, 138; 74/424.8 C
 References Cited
U.S. PATENT DOCUMENTS
4,397,610 8/1983 Krohn 417/44.2
5,004,403 4/1991 Culbertson et al 417/53
5,491,633 2/1996 Henry et al 74/424.8 C
FOREIGN PATENT DOCUMENTS
Primary Examiner—Timothy Thorpe
Assistant Examiner—Xuan M. Thai
Attorney, Agent, or Firm—Wallenstein & Wagner, Ltd.
A pressure regulated electric pump is characterized by a positive displacement double acting reciprocating pump driven by an electric motor through a planetary roller screw. A controller senses the pressure of liquid at an outlet from the pump and varies the speed of the motor in a manner to maintain the pressure substantially constant. At a constant flow demand from the pump the motor is operated at a substantially constant speed. As flow demand rises and falls the instantaneous pump outlet pressure falls and rises. The changing pressure is sensed by the controller which makes incremental changes in the speed of the motor to cause the motor to speed up during a pressure fall and to slow down during a pressure rise, in such manner as to maintain pump outlet pressure substantially constant. Using a planetary roller screw to couple the electric motor rotary output to the pump provides a load torque on the motor that is directly proportional to pump outlet pressure plus frictional losses in the pump and drive mechanism. The result is a decrease in the magnitude of pressure drops and spikes in the pumped liquid at the time of changeover of the pump, i.e., at the time the direction of reciprocation of the pump changes.
12 Claims, 3 Drawing Sheets