Marine macerator pump control module

• US 6,534,940 B2
• Filed: 06/18/2001
• Issued: 03/18/2003
• Est. Priority Date: 06/18/2001
• Status: Expired due to Fees

• Current Assignee: Don Blackmore, Jack Davidson, John Bell, Martin Foley, Ted Christensen, William Davidson
• Original Assignee: Smart Marine Systems, LLC
• Inventors: Bell, John J., Stoffel, Ronald Alan
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US09/884,680
• Publication Number:
  US 20020190687A1
• Time in Patent Office: 638 Days
• Field of Search: 431/9, 318/430, 318/431, 318/434, 318/445, 318/452, 318/454, 388/909
• US Class Current: 318/434
• CPC Class Codes: B63J 4/006 for treating waste water or sewage
• CPC Class Codes: F04D 15/0236 Lack of liquid level being detected by analysing the parameters of the electric drive, e.g. current or power consumption
• CPC Class Codes: H02H 7/0827 responsive to underload or no-load, e.g. pump-off control circuits for pump motors
• CPC Class Codes: H02P 7/285 controlling armature supply only
• CPC Class Codes: Y10S 388/909 Monitoring means

Abstract

A marine macerator switch including a comparator programmable with over and under current limits corresponding with the characteristics of a macerator drive motor. A sensing circuit senses the real time motor current and compares it with the current limits to, at respective predetermined differentials, shut the motor down. The control also includes a timer programmed to allow the motor to run for a period of time corresponding with that required for emptying of the tank.

Claims

1. An electrical controller for connection with a motor driving a marine macerator pump and of the type having maximum and minimum allowable currents, said controller comprising:

a housing;

electrical connectors on said housing for connecting in circuit between said motor and a power source;

a memory in said housing for storing maximum and minimum reference signals corresponding with the respective said maximum and minimum allowable currents, and a reference time signal corresponding with the maximum allowable motor operating time for one pumping operation;

a sensor in said housing and connected with said memory and said electrical connectors for sensing the real time current level drawn by said motor to produce a sensed signal;

a timer in said housing and operative to measure elapsed motor operating time to produce an elapsed time signal;

a comparator in said housing, connected with said memory, sensor and timer and operative in response to said sensed signal exceeding said maximum reference signal and to falling below said minimum reference signal to generate respective first and second stop signals, said comparator further operative to compare said elapsed time signal with said reference time signal and responsive to said elapsed time signal exceeding said reference time signal to generate a third stop signal; and

a control circuit in said housing connecting said connectors in circuit with said comparator and including a motor power switch, said control circuit responsive to a start signal to close said motor power switch to communicate power to said motor and responsive to either said first, second, or third stop signals, to open said motor power switch to remove power from said motor.

2. The controller of claim 1 wherein:

said memory includes a RAM and firmware, said RAM being operative to be initialized from said firmware with said respective maximum and minimum reference signals and said RAM also being operative to store a reference average current signal received from said sensor.

3. The controller of claim 1 wherein:

said control circuit includes a voltage regulator and reverse polarity protection diode to provide regulated power to said controller memory and logic circuits.

4. The controller of claim 1 wherein:

said motor power switch is a field effect transistor (FET) for switching power to said motor.

5. The controller of claim 1 wherein:

said sensor includes a trace resistor and an RC network to develop a filtered voltage in response to said motor current and an analog-to-digital converter and scaling circuitry to convert said filtered voltage to said sensed signal.

6. The controller of claim 1 wherein:

said control circuit includes a delay responsive to said first stop signal to delay opening of said motor power switch for a predetermined delay time at the motor startup.

7. An electrical controller as set forth in claim 1 for use with a motor of the type having an average operating current under the load of said pump and wherein:

said memory is operable to store a reference signal corresponding with said average operating current;

said comparator is operative to compare said sensed signal with said reference signal and is responsive to a differential there between exceeding a predetermined positive magnitude to generate a fourth stop signal; and

said control circuit is responsive to said fourth stop signal to open said motor power switch.

8. An electrical controller as set forth in claim 1 for use with a motor of the type having an average operating current under the load of said pump and wherein:

said memory is operable to store a reference signal corresponding with said average operating current;

said comparator is operative to compare said sensed signal with said reference signal and is responsive to a differential there between exceeding a predetermined negative magnitude to generate a fifth stop signal; and

said control circuit is responsive to said fifth stop signal to open said motor power switch.

9. The controller of claim 8 wherein:

said control circuit includes a delay responsive to said second and/or fifth stop signals to delay opening of said motor power switch for a predetermined delay time;

said control circuit is operative to, after said predetermined delay time, be responsive to said second and/or fifth stop signals, to generate a sixth stop signal; and

said control circuit is responsive to said sixth stop signal to open said motor power switch.

10. The control circuit of claim 9 wherein:

said control circuit includes a purge delay responsive to said sixth stop signal to delay opening of said motor power switch for a predetermined delay time.

11. A method of controlling a refuse disposal macerator pump driven by an electric motor, including:

determining the maximum time period for disposal of refuse by said macerator pump to establish a time limit and determining the respective maximum allowable high and low current deviations from an average motor operating current under load driving said macerator pump, said maximum high deviation indicative of onset of motor stall and said maximum low deviation indicative of completion of disposal of said refuse;

entering high and low deviation signals corresponding with said respective maximum allowable high and low current deviations in a comparator included in a controller of the type including said comparator and also including a timer operable to signal at said time limit;

starting said motor;

sensing the average operating current of said motor immediately after pump stabilization and entering an average current reference signal corresponding with said average operating current in said comparator;

repeatedly sensing the operating current of said motor and entering a real-time current signal corresponding with said operating current in said comparator;

repeatedly determining the deviations of said real-time current signal from said average current reference signal and comparing, in said comparator, said real-time deviation signals with the respective said high and low deviation signals to determine if either said high or low deviation has been exceeded; and

if said maximum or minimum deviations or said time limit are exceeded, turning off said motor.

12. The method of claim 11 that includes:

after said starting step, isolating said comparator from said motor for a motor stabilization period.

13. The method of claim 11 that includes:

in the event said low deviation is exceeded, delaying said turning-off step for a predetermined period, sensing said operating current again to generate a check signal to said comparator to be compared with said average current reference signal, and if said low deviation is exceeded, initiating said turning-off step.

14. The method of claim 11 that includes;

in the event said low deviation is exceeded, delaying said turning-off step for a predetermined period of time to allow said macerator pump to purge the remaining refuse therefrom.

15. An electrical controller for connection with a dc motor driving a marine macerator pump, said dc motor of the type having an average operating current under the load of operating said pump and maximum and minimum allowable currents, said controller comprising:

electrical connectors for connecting in circuit between said dc motor and an on-board battery power source;

a memory for storing a reference average signal corresponding with said average operating current, maximum and minimum reference signals corresponding with the respective said maximum and minimum allowable currents, and a reference time signal corresponding with the maximum allowable motor operating time for one pumping operation;

a sensor connected with said memory and said electrical connectors for sensing the real time current level drawn by said dc motor to produce a sensed signal;

a timer operative to measure elapsed motor operating time to produce an elapsed time signal;

a comparator connected with said memory, sensor and timer and operative to compare said sensed signal with the respective said maximum and minimum reference signals and responsive to said sensed signal exceeding the respective said maximum and minimum reference signals to generate respective first and second stop signals, said comparator further operative to compare said elapsed time signal with said reference time signal and responsive to said elapsed time signal exceeding said reference time signal to generate a third stop signal, said comparator further operative to compare said sensed signal with said reference average signal and responsive to the differential between said sensed signal and said reference average signal exceeding a predetermined positive magnitude to generate a fourth stop signal and responsive to the differential between said sensed signal and said reference average signal exceeding a predetermined negative magnitude to generate a fifth stop signal; and

a control circuit connecting said connectors in circuit with said comparator and including a voltage regulator and reverse voltage polarity protection diode to regulate power received from said battery power source to a predetermined voltage level suitable for said controller memory and logic circuits, said control circuit further including a field effect transistor (FET), said control circuit responsive to a start signal to turn on said FET to communicate power to said motor and responsive to either said first, second, third, fourth or fifth stop signals, to turn off said FET to remove power from said motor.

16. The controller of claim 15 wherein:

said memory includes a RAM and firmware, said RAM being operative to be initialized from said firmware with said respective maximum and minimum reference signals and said RAM also being operative to store said reference average signal received from said sensor.

17. The controller of claim 15 wherein:

said sensor includes a trace resistor and an RC network to develop a filtered voltage in response to said dc motor current and an analog-to-digital converter and scaling circuitry to convert said filtered voltage to said sensed signal.

18. The controller of claim 15 wherein:

said control circuit includes a delay responsive to said first stop signal to delay turning off said FET for a predetermined delay time at the dc motor startup.

19. The controller of claim 15 wherein:

said control circuit includes a delay responsive to said second and/or fifth stop signals to delay turning off said FET for a predetermined delay time;

said control circuit is operative to, after said predetermined delay time, be responsive to said second and/or fifth stop signals to generate a sixth stop signal; and

said control circuit is responsive to said sixth stop signal to turn off said FET.

20. The control circuit of claim 19 wherein:

said control circuit includes a purge delay responsive to said sixth stop signal to delay turning off said FET for a predetermined delay time.

21. A marine refuse disposal system in circuit between a battery and dc motor driving a macerator pump, said dc motor of the type having an average operating current under the load of operating said pump and maximum and minimum allowable currents, said system, comprising:

a refuse holding tank;

an electrical controller connected with said dc motor;

a memory for storing a reference average signal corresponding with said average operating current, maximum and minimum reference signals corresponding with the respective said maximum and minimum allowable currents, and a reference time signal corresponding with the maximum time required for said pump to empty said tank;

a sensor connected with said memory and operative in response to the real time current level drawn by said dc motor to produce a sensed signal;

a timer operative to measure elapsed motor operating time to produce an elapsed time signal;

a comparator connected with said memory, sensor and timer and operative to compare said sensed signal with the respective said maximum and minimum reference signals and responsive to said sensed signal exceeding the respective said maximum and minimum reference signals to generate respective first and second stop signals, said comparator further operative to compare said elapsed time signal with said reference time signal and responsive to said elapsed time signal exceeding said reference time signal to generate a third stop signal, said comparator further operative to compare said sensed signal with said reference average signal and responsive to the differential between said sensed signal and said reference average signal exceeding a predetermined positive magnitude to generate a fourth stop signal and responsive to the differential between said sensed signal and said reference average signal exceeding a predetermined negative magnitude to generate a fifth stop signal; and

a control circuit in circuit with said comparator and including a voltage regulator and reverse voltage polarity protection diode to regulate power received from said battery to a predetermined voltage level suitable for said controller memory and logic circuits, said control circuit further including a field effect transistor (FET), said control circuit responsive to a start signal to turn on said FET to communicate power to said motor and responsive to either said first, second, third, fourth or fifth stop signals, turn off said FET to remove power from said motor.

22. The system of claim 21 wherein:

said memory includes a RAM and firmware, said RAM being operative to be initialized from said firmware with said respective maximum and minimum reference signals and said RAM also being operative to store said reference average signal received from said sensor.

23. The system of claim 21 wherein:

said sensor includes a trace resistor and an RC network to develop a filtered voltage in response to said dc motor current and an analog-to-digital converter and scaling circuitry to convert said filtered voltage to said sensed signal.

24. The system of claim 21 wherein:

said control circuit includes a delay responsive to said first stop signal to delay turning off said FET for a predetermined delay time at the dc motor startup.

25. The system of claim 21 wherein:

said control circuit includes a delay responsive to said second and/or fifth stop signals to delay turning off said FET for a predetermined delay time;

said control circuit is operative to, after said predetermined delay time, be responsive to said second and/or fifth stop to generate a sixth stop signal; and

said control circuit is responsive to said sixth stop signal to turn off said FET.

26. The system of claim 25 wherein:

said control circuit includes a purge delay responsive to said sixth stop signal to delay turning off said FET for a predetermined delay time.