Solid state liquid level sensor and pump controller

• US 6,499,961 B1
• Filed: 10/26/2000
• Issued: 12/31/2002
• Est. Priority Date: 03/16/2000
• Status: Expired due to Fees

• Current Assignee: Tecumseh Products Company
• Original Assignee: Tecumseh Products Company
• Inventors: Terry, Robert L., Wyatt, Arnold G.
• Primary Examiner(s): Bennett, Henry
• Assistant Examiner(s): DAHBOUR, HENRY
• Application Number:
  US09/696,905
• Time in Patent Office: 796 Days
• Field of Search: 417/36, 417/40, 417/32, 417/44.1, 733/04.C, 307/118, 137/392, 340/620, 340/623, 340/624, 340/625
• US Class Current: 417/36
• CPC Class Codes: F04B 49/025 by means of floats
• CPC Class Codes: G05D 9/12 characterised by the use of electric means

Abstract

A liquid level controller for a device having a liquid reservoir includes a control board and a reservoir assembly. The reservoir assembly is disposed within the reservoir and includes a liquid level sensor, which is electrically connected to the control circuit. The control board includes a control circuit and a pump. The control circuit has a control circuit and a resistive power supply to power the control circuit. The control circuit controls the pump in response to signals from the level sensor and includes a CMOS logic gate and a MOSFET transistor to switch the pump. The control circuit further includes a second resistive power supply connected to a relay which controls an alarm. The second power supply is activated by a transistor responsive to an alarm signal from the level sensor, and powers the relay only when the alarm signal is present.

Claims

1. A circuit for maintaining the level of liquid in a reservoir by controlling the operation of a pump for removing liquid from the reservoir in response to a start signal from a liquid level sensor indicating that the liquid level is outside a desired range, the circuit including:

a resistive power supply to power the circuit;

a logic gate for outputting a pump signal in response to receipt of the start signal; and

a transistor electrically connected between the logic gate and the pump, the transistor enabling the pump in response to receipt of the pump signal.

2. The circuit of claim 1 wherein the level sensor provides a stop signal indicating that the liquid level is within the desired range, the logic gate outputting the pump signal in response to simultaneous receipt of both the start signal and the stop signal.

3. The circuit of claim 1 wherein the logic gate is a CMOS AND gate.

4. The circuit of claim 1 wherein the transistor is a MOSFET transistor, the logic gate providing the pump signal to a gate of the transistor.

5. The circuit of claim 1 wherein the pump is non-isolated.

6. The circuit of claim 1 further including a circuit board including the resistive power supply, the transistor, and the pump, the pump being encapsulated on the board.

7. The circuit of claim 1 further including a second resistive power supply for powering an alarm, the second resistive power supply being inactive except when power is required to operate the alarm.

8. The circuit of claim 7 wherein the level sensor provides an alarm signal, the circuit further including a transistor being activated by the alarm signal, activation of the transistor causing the second resistive power supply to activate a relay coupled to the alarm, thereby activating the alarm.

9. A controller for a liquid reservoir having a sensor disposed within the reservoir, the sensor outputting a start signal indicating a level of the liquid in the reservoir, the controller including:

a control circuit coupled to the sensor for receiving the start signal, the control circuit including a transistor; and

a non-isolated pump electrically connected to the transistor, the pump adjusting the liquid level when activated;

wherein the control circuit activates the pump in response to receipt of the start signal.

10. The controller of claim 9 wherein the transistor activates the pump when enabled and deactivates the pump when disabled.

11. The controller of claim 10 wherein the control circuit includes a logic gate for receiving the start signal, the logic gate enabling the transistor in response to receipt of the start signal.

12. The controller of claim 11 wherein the logic gate is a CMOS AND gate.

13. The controller of claim 10 wherein the transistor is a MOSFET transistor.

14. The controller of claim 10 further including a circuit board, the transistor and the pump being mounted to the circuit board.

15. The controller of claim 9 wherein the sensor outputs a stop signal, the control circuit activating the pump in response to simultaneous receipt of both the start signal and the stop signal.

16. The controller of claim 9 wherein the control circuit includes a resistive power supply to power the control circuit.

17. The controller of claim 9 wherein the control circuit includes a first resistive power supply providing a first output voltage to power the control circuit, and a second resistive power supply providing a second output voltage to activate an alarm coupled to the control circuit.

18. The controller of claim 9 wherein the control circuit includes a resistive power supply for powering an alarm, the resistive power supply being inactive except when power is required to operate the alarm.

19. The controller of claim 18 wherein the sensor outputs an alarm signal, the control circuit further including a transistor being activated by the alarm signal, activation of the transistor causing the resistive power supply to activate a relay coupled to the alarm, thereby activating the alarm.

20. A controller for a device having a liquid reservoir and an alarm, including:

a first resistive power supply for converting an AC power input to a first DC voltage;

a control circuit powered by the first DC voltage;

a non-isolated pump coupled to the control circuit;

a second resistive power supply for converting the AC power input to a second DC voltage; and

an alarm circuit using the second DC voltage to activate the alarm.

21. The controller of claim 20 wherein a sensor disposed in the reservoir provides a start signal to the control circuit when the level of liquid in the reservoir reaches a first predetermined level, the control circuit outputting a pump signal in response to receipt of the start signal to activate the pump, the pump adjusting the level of liquid in the reservoir.

22. The controller of claim 21 wherein the sensor provides a stop signal to the control circuit when the level of liquid in the reservoir reaches a second predetermined level, the control circuit outputting the pump signal in response to simultaneous receipt of both the start signal and the stop signal.

23. The controller of claim 21 wherein the control circuit includes a logic gate and a transistor coupled between the logic gate and the pump, the transistor enabling the pump in response to receipt of the pump signal.

24. The controller of claim 23 wherein the logic gate is a CMOS AND gate.

25. The controller of claim 23 wherein the transistor is a MOSFET transistor, the logic gate providing the pump signal to a gate of the transistor.

26. The controller of claim 20 further including a circuit board including the first resistive power supply and the pump, the pump being encapsulated on the board.

27. The controller of claim 20 wherein the second resistive power supply is inactive except when power is required to operate the alarm.

28. The controller of claim 20 wherein a sensor disposed in the reservoir provides an alarm signal, the control circuit further including a transistor being activated by the alarm signal, activation of the transistor causing the second resistive power supply to activate a relay coupled to the alarm, thereby activating the alarm.

29. A circuit for maintaining the level of liquid in a reservoir by controlling the operation of a pump for removing liquid from the reservoir in response to a start signal from a liquid level sensor indicating that the liquid level is outside a desired range, the circuit including:

a resistive power supply to power the circuit;

a logic gate for outputting a pump signal in response to receipt of the start signal; and

a transistor coupled between the logic gate and the pump, the transistor enabling the pump in response to receipt of the pump signal;

wherein the logic gate is a CMOS AND gate.

30. A circuit for maintaining the level of liquid in a reservoir by controlling the operation of a pump for removing liquid from the reservoir in response to a start signal from a liquid level sensor indicating that the liquid level is outside a desired range, the circuit including:

a resistive power supply to power the circuit;

a logic gate for outputting a pump signal in response to receipt of the start signal; and

a transistor coupled between the logic gate and the pump, the transistor enabling the pump in response to receipt of the pump signal;

wherein the transistor is a MOSFET transistor, the logic gate providing the pump signal to a gate of the transistor.

31. A circuit for maintaining the level of liquid in a reservoir by controlling the operation of a pump for removing liquid from the reservoir in response to a start signal from a liquid level sensor indicating that the liquid level is outside a desired range, the circuit including:

a resistive power supply to power the circuit;

a logic gate for outputting a pump signal in response to receipt of the start signal;

a transistor coupled between the logic gate and the pump, the transistor enabling the pump in response to receipt of the pump signal; and

a circuit board including the resistive power supply, the transistor, and the pump, the pump being encapsulated on the board.

32. A circuit for maintaining the level of liquid in a reservoir by controlling the operation of a pump for removing liquid from the reservoir in response to a start signal from a liquid level sensor indicating that the liquid level is outside a desired range, the circuit including:

a resistive power supply to power the circuit;

a logic gate for outputting a pump signal in response to receipt of the start signal;

a transistor coupled between the logic gate and the pump, the transistor enabling the pump in response to receipt of the pump signal; and

a second resistive power supply for powering an alarm, the second resistive power supply being inactive except when the power is required to operate the alarm.

33. The circuit according to claim 32, wherein the level sensor provides an alarm signal, the circuit further including a transistor being activated by the alarm signal, activation of the transistor causing the second resistive power supply to activate a relay coupled to the alarm, thereby activating the alarm.

34. A controller for a liquid reservoir having a sensor disposed within the reservoir, the sensor outputting a start signal indicating a level of the liquid in the reservoir, the controller including:

a control circuit coupled to the sensor for receiving the start signal; and

a non-isolated pump connected to the control circuit, the pump adjusting the liquid level when activated;

wherein the control circuit activates the pump in response to receipt of the start signal;

wherein the control circuit includes a transistor coupled to the pump, the transistor activating the pump when enabled and deactivating the pump when disabled;

wherein the control circuit includes a logic gate for receiving the start signal, the logic gate enabling the transistor in response to receipt of the start signal;

wherein the logic gate is a CMOS AND gate.

35. A controller for a liquid reservoir having a sensor disposed within the reservoir, the sensor outputting a start signal indicating a level of the liquid in the reservoir, the controller including:

a control circuit coupled to the sensor for receiving the start signal; and

a non-isolated pump connected to the control circuit, the pump adjusting the liquid level when activated;

wherein the control circuit activates the pump in response to receipt of the start signal;

wherein the control circuit includes a transistor coupled to the pump, the transistor activating the pump when enabled and deactivating the pump when disabled;

wherein the transistor is a MOSFET transistor.

36. A controller for a liquid reservoir having a sensor disposed within the reservoir, the sensor outputting a start signal indicating a level of the liquid in the reservoir, the controller including:

a control circuit coupled to the sensor for receiving the start signal; and

a non-isolated pump connected to the control circuit, the pump adjusting the liquid level when activated; and

a circuit board, the transistor and the pump being mounted to the circuit board;

wherein the control circuit activates the pump in response to receipt of the start signal;

wherein the control circuit includes a transistor coupled to the pump, the transistor activating the pump when enabled and deactivating the pump when disabled.

37. A controller for a liquid reservoir having a sensor disposed within the reservoir, the sensor outputting a start signal indicating a level of the liquid in the reservoir, the controller including:

a control circuit coupled to the sensor for receiving the start signal; and

a non-isolated pump connected to the control circuit, the pump adjusting the liquid level when activated;

wherein the control circuit activates the pump in response to receipt of the start signal;

wherein the control circuit includes a first resistive power supply providing a first output voltage to power the control circuit, and a second resistive power supply providing a second output voltage to activate an alarm coupled to the control circuit.

38. A controller for a liquid reservoir having a sensor disposed within the reservoir, the sensor outputting a start signal indicating a level of the liquid in the reservoir, the controller including:

a control circuit coupled to the sensor for receiving the start signal; and

a non-isolated pump connected to the control circuit, the pump adjusting the liquid level when activated;

wherein the control circuit activates the pump in response to receipt of the start signal;

wherein the control circuit includes a resistive power supply for powering an alarm, the resistive power supply being inactive except when power is required to operate the alarm.

39. The controller of claim 38, wherein the sensor outputs an alarm signal, the control circuit further including a transistor being activated by the alarm signal, activation of the transistor causing the resistive power supply to activate a relay coupled to the alarm,