Pump control apparatus and method

• US 5,324,170 A
• Filed: 06/03/1993
• Issued: 06/28/1994
• Est. Priority Date: 12/31/1984
• Status: Expired due to Term

• Current Assignee: Rule Industries Incorporated (ITT, Inc.)
• Original Assignee: Rule Industries Incorporated (ITT, Inc.)
• Inventors: Boyd, Stephen B., Anastos, William N.
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): Scheuermann, David W.
• Application Number:
  US08/071,331
• Time in Patent Office: 390 Days
• Field of Search: 417/12, 417/22, 417/24, 417/44 J, 417/53
• US Class Current: 417/12
• CPC Class Codes: H02H 7/08 for dynamo-electric motors

Abstract

Disclosed herein is an apparatus and method for controlling electrically powered liquid-moving pumps, particularly bilge and sump pumps. The apparatus is characterized by the fact that no portion thereof need be located in the hostile environment of the bilge or sump served by the pump controlled thereby.

Claims

1. Pump control apparatus comprising:

(a) a switch for insertion in a power supply circuit or an electrically driven pump for liquids;

(b) interval timer means effective to produce an "on" signal at regular time intervals;

(c) electrical condition sensing means for insertion in said power supply circuit of said pump and being effective to (1) monitor an electrical condition of said power supply circuit responsive to pumping load and (2) produce an "off" signal in response to a sensed change in said electrical condition upon liquid starvation of said pump; and

(d) a switch control circuit communicating with each of (a), (b) and (c), said circuit being responsive to (1) the "on" signal of said interval timer means of (b) by closing said switch at the beginning of each said regular time interval and (2) the "off" signal of said electrical condition sensing means of (c) by opening said switch;

wherein, in the absence of an "off" signal from said electrical condition sensing means prior to the occurrence of the next "on" signal, said switch control circuit of (d) keeps said switch closed and thereby said pump operating without interruption until at least the occurrence of said next "on" signal.

2. The pump control apparatus of claim 1 wherein said electrical condition sensing means of (c) is a sensor resistor and the electrical condition sensed thereby is current.

3. The pump control apparatus of claim 2 wherein said switch control circuit of (d) includes an undercurrent detector to sense an undercurrent "off" signal of said sensor resistor, said undercurrent detector being operative to open said switch.

4. The pump control apparatus of claim 3 wherein said switch is a relay having mechanical contact elements and said switch control circuit includes a clamp timer adapted to temporarily delay operation of said undercurrent detector for a period of time sufficient to allow the mechanical contact elements of said switch to make contact and to thereby close said power supply circuit of said pump following said "on" signal of said interval timer.

5. The pump control apparatus of claim 2 wherein said switch control circuit of (d) includes an overcurrent detector to sense an overcurrent signal of said sensor resistor, said overcurrent detector being operative to open said switch.

6. The pump control apparatus of claim 5 wherein said switch control circuit of (d) includes a buffer stage to filter electrical noise from the signal output of said sensor resistor and to prevent injection of a transient overcurrent signal to said overcurrent detector upon start up of the pump.

7. A method for controlling electrically powered pump apparatus which comprises:

(a) operating a pump by closing a power supply circuit to a prime mover of said pump apparatus at regular time intervals;

(b) monitoring an electrical condition of said power supply circuit throughout the pumping cycle of said pump, said electrical condition being responsive to the pumping load of said pump;

(c) upon a change of said monitored electrical condition signalling a reduction in the pumping load and the onset of starvation of said pump, opening said power supply circuit to stop operation of said pump; and

(d) in the absence of a change of said monitored electrical condition signalling a reduction in the pumping load and the onset of starvation of said pump prior to the beginning of the next regular time interval, keeping said power supply circuit closed and thereby said pump operating without interruption until at least the beginning of said next regular time interval.

8. A pump/pump control system comprising:

(A) a pump component driven by an electrically powered prime mover having a power supply circuit thereto, and

(B) a pump control apparatus component comprising;

(a) a switch inserted in the power supply circuit of said pump component of (A);

(b) interval timer means effective to produce an "on" signal at regular time intervals;

(c) electrical condition sensing means communicating with prime mover power supply circuit of said pump of (A) and being effective to (1) monitor an electrical condition of said prime mover power supply circuit responsive to pumping load and (2) produce an "off" signal in response to a sensed change in said electrical condition upon liquid starvation of said pump component of (A); and

(d) a switch control circuit communicating with each of (a), (b) and (c), said circuit being responsive to (1) the "on" signal of said interval timer means of (b) by closing said switch of (a) at the beginning of each said regular time interval and (2) the "off" signal of said electrical condition sensing means of (c) by opening said switch;

wherein, in the absence of an "off" signal from said electrical condition sensing means prior to the occurrence of the next "on" signal, said switch control circuit of (d) keeps said switch closed and thereby said pump operating without interruption until at least the occurrence of said next "on" signal.

9. The pump/pump control system of claim 8 wherein said pump control apparatus component of (B) is a discrete component relative to said pump component of (A) and is located remotely therefrom.

10. The pump/pump control system of claim 8 wherein said pump control apparatus component of (B) is physically integrated with the pump component of (A).

11. Apparatus for controlling the operation of a prime mover of a pump for pumping liquids, said prime mover being driven from a power circuit, comprising

a timer for timing a succession of pump "on" times at regular time intervals,

a sensor for sensing an electrical condition in said power circuit, said electrical condition being responsive to the pumping condition of said pump, and

a control circuit (a) for conditioning said power circuit to enable the delivery of power to said prime mover beginning when each said "on" time occurs, (b) for disabling the delivery of power from said power circuit to said prime mover in response to the sensing of said electrical condition by said sensor, and (c) in the absence of the sensing of said electrical condition prior to the occurrence of the next "on" time, for continuing to condition said power circuit to enable the delivery of power to said prime mover without interruption until at least the occurrence of said next "on" time.

12. The apparatus of claim 11 wherein said electrical condition comprises a current being delivered from said power circuit to said prime mover rising above a predetermined threshold.

13. The apparatus of claim 11 wherein said sensor comprises circuitry for sensing current being delivered from said power circuit to said prime mover.

14. The apparatus of claim 13 wherein said control circuit comprises a mechanical relay and a circuit for temporarily delaying the response of said control circuit to said electrical current falling below said predetermined level, for a period of time following each said "on" time sufficient for said relay to close.

15. The apparatus of claim 11 wherein said circuitry comprises a resistor connected so that the voltage across said resistor is indicative of current being delivered from said power circuit to said prime mover.

16. The apparatus of claim 15 wherein said control circuit comprises a buffer stage to filter electrical noise from said resistor voltage.

17. The apparatus of claim 15 wherein said control circuit comprises circuitry for comparing said voltage across said resistor with a reference which is based on the condition of said prime mover.

18. A method for controlling the operation of a prime mover of a pump for pumping liquids, said prime mover being driven from a power circuit, comprising

timing a succession of pump "on" times at regular time intervals,

sensing an electrical condition in said power circuit, said electrical condition being responsive to the pumping condition of said pump,

conditioning said power circuit to enable the delivery of power to said prime mover beginning when each said "on" time occurs,

disabling the delivery of power from said power circuit to said prime mover in response to the sensing of said electrical condition by said sensor, and

in the absence of the sensing of said electrical condition prior to the occurrence of the next "on" time, continuing to condition said power circuit to enable the delivery of power to said prime mover without interruption until at least the occurrence of said next "on" time.

19. The method of claim 18 wherein said sensing comprises sensing current being delivered from said power circuit to said prime mover.

20. A method for causing the level of a liquid in a vessel to tend to stay below a predetermined level, comprising

a. placing an inflow port of an electrical pump in said vessel at a position associated with said predetermined level,

b. causing said pump to pump said fluid beginning at regular time intervals which are independent of the level of fluid in said vessel,

c. sensing the magnitude of electrical power drawn by said pump as an indication of said liquid being at or above said predetermined level, and, if so causing said pump to continue to pump,

d. stopping said pump from pumping said fluid if it is sensed that said liquid is below said predetermined level, and

e. in the absence of an indication that said liquid is below said predetermined level prior to the beginning of the next regular time interval, continuing to cause said pump to pump said fluid without interruption until at least the beginning of said next regular time interval.

21. The method of claim 20 further comprising repeating steps b and c.

22. The method of claim 20 wherein steps b and c are repeated at regularly predetermined intervals.

23. The method of claim 22 wherein said intervals are each at least as brief as 5 minutes long.

24. The method of claim 20 further comprising

d. sensing the magnitude of electrical power drawn by said pump as an indication of said liquid being below said level, and, if so, causing said pump to interrupt pumping.

25. The method of claim 20 wherein step c begins a brief time after step b occurs.

26. A method of controlling an electrically-driven liquid pump comprising

issuing a first turn on signal to the pump at a first time which is arbitrary relative to the level of said liquid in a vessel,

sensing the magnitude of electrical power drawn by said pump,

continuing to operate said pump if the magnitude of electrical power drawn by said pump satisfies predetermined criteria,

turning off said pump if the magnitude of electrical power drawn by said pump satisfies other predetermined criteria,

issuing a second turn on signal to the pump at a time which occurs a predetermined time period following the first time, and

in the absence of the magnitude of electrical power drawn by said pump satisfying said other predetermined criteria prior to the issuance of said second turn on signal, continuing to operate said pump without interruption until at least the issuance of said second turn on signal.

27. A method of controlling an electrically-driven liquid pump for pumping liquid from a vessel comprising

issuing a turn-on signal to the pump at regular time intervals and at least as frequently as every five minutes regardless of the level of liquid in the vessel,

issuing a turn-off signal to the pump prior to the next turn-on signal only if (1) the liquid in the vessel falls below a predetermined level or (2) the pump becomes mechanically jammed and incapable of pumping, and

in the absence of said turn-off signal prior to a next said turn-on signal, continuing to operate the pump without interruption until at least the issuance of said next turn-on signal.