US 5,456,581 A · Control system for a multi-piston pump with solenoid valves for the production of constant outlet pressure flow

Abstract

A multi-piston pump is provided which uses microprocessor controlled check all valves to control flow rate of a fluid at the pump's outlet port. The pump includes nine cylindrical shaped chambers and associated reciprocating pistons which are driven by a cam attached to a shaft. The pump's shaft is coupled to the shaft of a motor which, in turn, drives the pump's shaft and cam resulting in a fluid, such as seawater, filling each of the nine chambers and then having the fluid forced from the chamber by the movement of its associated piston from bottom dead center to top dead center. A pressure transducer which monitors the pressure at the pump's outlet port and a shaft encoder which monitors the angular position of the pump's shaft respectively provide analog signals indicative of the pump's outlet port's pressure and the shaft's angular position. A microprocessor receives these analog signals in a digital form, processes the signals and provides digital pulse signals to either extend or retract the rod of nine solenoids depending upon the pressure at the pump's outlet port. Each of the nine solenoid rods when extended engage a check ball valve within one of the pumps nine inlet passageways allowing the passageway to remain open when the associated reciprocating piston is in a pumping stroke. This allows seawater to be discharged through the inlet passageway maintaining fluid flow at the outlet port at a pressure level which is commensurate with the intended use of the pump.

A multi-piston pump comprising:

a housing having a plurality of cylindrical shaped chambers, each of said cylindrical shaped members having an inlet passageway connecting said cylindrical shaped chamber to an external supply of a fluid and an outlet passageway connecting said cylindrical shaped chamber to an outlet port of said housing;
a plurality of reciprocating pistons, one of said reciprocating pistons being positioned within a corresponding one of said cylindrical shaped chambers, each of said reciprocating pistons being adapted for reciprocating movement;
a cam mounted within said housing, said cam being mounted within said housing to allow for rotational movement of said cam within said housing;
a shaft having one end connected to said cam and an opposite end connected to a drive source, said drive source imparting rotational movement upon said shaft and said cam;
encoder means coupled to said shaft, said encoder means measuring an angular position of shaft and providing a first analog signal indicative of the angular position of said shaft;
said cam driving each of said reciprocating pistons from a bottom dead center position to a top dead center position within the corresponding one of said cylindrical shaped chambers for each of said reciprocating pistons forcing said fluid from the corresponding one of said cylindrical shaped chamber;
a plurality of check ball valves, one of said check ball valves being positioned within a corresponding one of said inlet passageways;
a plurality of solenoids mounted on said housing, each of said solenoids having a rod extending from said solenoid through an aperture within said housing;
pressure monitoring means positioned at the outlet port of said housing for monitoring a pressure of said fluid at the outlet port of said housing, said pressuring monitoring means providing a second analog signal indicative of the pressure of said fluid at the outlet port of said housing;
processing means for receiving said first and said second analog signals and calculating an average pressure over a predetermined angle of rotational movement of said shaft for each of said solenoids;
said processing means calculating said average pressure in accordance with the following equation:
##EQU2## wherein P.sub.AVG is said average pressure occurring at the outlet port of said housing for a rotation of said shaft over said predetermined angle of rotational movement;
P.sub.TOTAL is a summation of pressure measurements made by said pressure monitoring means over said predetermined angle of rotational movement and N is a predetermined number of sample measurements taken by said pressure monitoring means over said predetermined angle of rotational movement;
said processing means actuating each of said solenoids for one revolution of said shaft at a corresponding solenoid decision point for each of said solenoids whenever said average pressure exceeds a predetermined threshold pressure level;
the rod of each of said solenoids being actuated extending to engage said check ball valve within the corresponding one of said inlet passageways allowing said fluid to be discharged through the corresponding one of said inlet passageways maintaining the pressure of said fluid at the outlet port of said housing at about said predetermined pressure level.

12 more elements

Control system for a multi-piston pump with solenoid valves for the production of constant outlet pressure flow

Life of this patent

Control system for a multi-piston pump with solenoid valves for the production of constant outlet pressure flow

Life of this patent

Abstract

Claims14