Pressure regulated electric pump
First Claim
1. A pressure regulated electric pump for delivering at least a minimum volume flow rate of pumped liquid, comprising:
- a positive displacement double acting reciprocating pump having an outlet for delivering pumped liquid and an inlet for connection to a supply of liquid;
means for sensing the pressure of pumped liquid;
an electric motor having a rotary output;
a planetary roller screw assembly coupled between said electric motor rotary output and said pump for converting said rotary output of said motor to a reciprocating output that reciprocates said pump through pumping strokes; and
controller means responsive to said pressure sensing means for controlling the direction and speed of rotation of said motor rotary output to operate said pump through pumping strokes at rates controlled to maintain a substantially constant pressure of pumped liquid despite changes in the volume flow rate of pumped liquid.
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Accused Products
Abstract
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.
36 Citations
12 Claims
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1. A pressure regulated electric pump for delivering at least a minimum volume flow rate of pumped liquid, comprising:
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a positive displacement double acting reciprocating pump having an outlet for delivering pumped liquid and an inlet for connection to a supply of liquid; means for sensing the pressure of pumped liquid; an electric motor having a rotary output; a planetary roller screw assembly coupled between said electric motor rotary output and said pump for converting said rotary output of said motor to a reciprocating output that reciprocates said pump through pumping strokes; and controller means responsive to said pressure sensing means for controlling the direction and speed of rotation of said motor rotary output to operate said pump through pumping strokes at rates controlled to maintain a substantially constant pressure of pumped liquid despite changes in the volume flow rate of pumped liquid. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A pressure regulated electric pump for delivering at least a minimum volume flow rate of pumped liquid, comprising:
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a positive displacement double acting reciprocating pump having an outlet for delivering pumped liquid and an inlet for connection to a supply of liquid; means for sensing the pressure of pumped liquid; a planetary roller screw assembly having a roller screw and a roller screw nut that is reciprocated by and along said roller screw in a direction and at a speed in accordance with the direction and speed of rotation of said roller screw; means for coupling said roller screw nut to said pump to reciprocate said pump, conjointly with said roller screw nut, through pumping strokes in a direction and at a rate in accordance with the direction and speed of rotation of said roller screw; and electric motor means responsive to said pressure sensing means for rotating said roller screw alternately in opposite directions at speeds of rotation in accordance with the sensed pressure of pumped liquid to reciprocate said pump through pumping strokes at rates that maintain a substantially constant pressure of pumped liquid despite variations in the volume flow rate of pumped liquid. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification