Capacitive Sensor and Method and Apparatus for Controlling a Pump Using Same

• US 20080229819A1
• Filed: 03/17/2008
• Published: 09/25/2008
• Est. Priority Date: 03/19/2007
• Status: Active Grant

• Current Assignee: Wayne/Scott Fetzer Company (Berkshire Hathaway Incorporated)
• Original Assignee: Wayne Water Systems Incorporated /Scott Fetzer Company
• Inventors: Mayleben, Philip Anthony, Stetter, Thomas Richard
• Granted Patent: US 8,380,355 B2
• Time in Patent Office: Days
• US Class Current: 73/304C
• CPC Class Codes: F04B 49/06 Control using electricity regulating by means of floats actuating electric switches F04B49/04
• CPC Class Codes: G01F 23/263 by measuring variations in capacitance of capacitors
• CPC Class Codes: G01F 23/266 measuring circuits therefor
• CPC Class Codes: G01F 23/268 mounting arrangements of probes
• CPC Class Codes: G01F 23/30 by floats
• CPC Class Codes: H01G 5/0132 Liquid dielectrics
• CPC Class Codes: H01G 5/019 Means for correcting the capacitance characteristics
• CPC Class Codes: Y10T 29/435 Solid dielectric type
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

A variable capacitor for sensing the level of a liquid. The capacitor provides a readable capacitance that varies with respect to the level of the liquid. A pump control system implementing the capacitive sensor to control the level of a liquid by activating and deactivating the pump depending on the level of the liquid. Methods relating to varying capacitance of a capacitive sensor and controlling a pump based on the level of a liquid. A pump controller for controlling the level of a liquid in a reservoir includes a controller and a capacitor. The capacitor is adapted to provide an activation signal to the controller when the liquid in the reservoir reaches a first predetermined level relative thereto. Additionally, the capacitor is adapted to provide a trigger signal to the controller when the liquid in the reservoir reaches a second predetermined level relative thereto. Based on the trigger signal, the controller determines when to deactivate the pump.

Claims

1. A variable capacitor comprising:

a first electrode;

a second electrode; and

a dielectric connecting the first and second electrode to form a capacitor having a readable capacitance, the dielectric having a first part made of an insulative material and a second part made of a liquid having a level that changes with respect to the insulative material which causes a change in the capacitance of the capacitor.

2. The variable capacitor of claim 1 wherein the first and second electrodes are encased in the insulative material of the dielectric in order to avoid exposing the electrodes to the liquid.

3. The variable capacitor of claim 1 wherein the insulative material is made at least in part of a polymer and the liquid comprises a substance that alters how the insulative material acts as a dielectric.

4. A capacitive sensor comprising:

a capacitor at least partially immersed in a liquid having a level that changes in relation to the capacitor, the capacitor having a variable capacitance depending on the level of the liquid; and

a circuit connected to the capacitor to determine the capacitance of the capacitor and thereby determine the level of the liquid.

5. The capacitive sensor of claim 4 wherein the circuit connected to the capacitor is an integrated circuit capable of detecting changes in capacitance based on changes in liquid level.

6. The capacitive sensor of claim 5 wherein the integrated circuit is a capacitance-to-digital converter capable of transmitting data relating to capacitance to a controller for processing.

7. The capacitive sensor of claim 5 wherein the integrated circuit is a controller capable of reading and processing data relating to the capacitance of the capacitor.

8. The capacitive sensor of claim 5, further comprising a heat sink connected to a circuit board of the integrated circuit by a switching device.

9. The capacitive sensor of claim 8, wherein the heat sink comprises a plate-shaped member connected to the circuit board by the switching device.

10. The capacitive sensor of claim 4, further comprising a housing for enclosing the capacitor and the circuit therein;

and

a protective material disposed within the housing to protect at least the circuit from liquid.

11. The capacitive sensor of claim 10, wherein the protective material comprises a potting material.

12. The capacitive sensor of claim 11, wherein the potting material comprises a first potting material and a second potting material.

13. The capacitive sensor of claim 12, wherein the second potting material is disposed on the first potting material.

14. The capacitive sensor of claim 13, wherein the second potting material is an acid resistant potting material.

15. A pump control for controlling a liquid level in a reservoir, comprising:

a pump;

a controller electrically connected to the pump for activating and deactivating the pump; and

a capacitor for providing a first capacitance to the controller for activating the pump and a second capacitance to the controller for deactivating the pump.

16. The pump control of claim 15, wherein the first capacitance corresponds to a first liquid level in the reservoir and the second capacitance corresponds to a second liquid level in the reservoir.

17. The pump control of claim 15, wherein the controller determines a run-time based on when the second capacitance was detected relative to when the first capacitance was detected, the run-time being an amount of time the pump should be activated to move a predetermined amount of the liquid out of the reservoir.

18. The pump control of claim 17, wherein the controller deactivates the pump after the run-time passes.

19. The pump control of claim 15, wherein the controller deactivates the pump upon detecting the second capacitance from the capacitor.

20. The pump control of claim 15, wherein the capacitor is a variable capacitor capable of providing a plurality of different capacitances with each capacitance corresponding to a different liquid level in the reservoir.

21. The pump control of claim 20, further comprising a power source generating an alternating current and wherein the controller detects the capacitance of the capacitor each time the alternating current is at a zero-crossing.

22. The pump control of claim 15, further comprising a secondary pump system comprising a pump and a liquid level sensor.

23. The pump control of claim 22, wherein the secondary pump system includes a wireless receiver for receiving information about at least the secondary pump system transmitted by a transmitter operably connected to the pump of the secondary pump system.

24. A pump control, comprising:

a pump for moving a liquid out of a reservoir; and

a controller electrically connected to the pump for activating the pump and determining a mm-time for the pump in order to move a desired amount of the liquid out of the reservoir.

25. The pump control of claim 24, wherein the run-time is based on a rate of flow of the liquid out of the reservoir.

26. The pump control of claim 24, further comprising a sensor in communication with the controller for detecting a first condition for activating the pump and a second condition for determining the run-time.

27. The pump control of claim 26, wherein the sensor includes at least one magnet and at least one magnetic sensor.

28. The pump control of claim 26, wherein the sensor includes at least one capacitive sensor.

29. The pump control of claim 28, wherein the at least one capacitive sensor includes a variable capacitor for generating a plurality of different capacitances with each capacitance corresponding to a different liquid level in the reservoir.

30. The pump control of claim 28, wherein the at least one capacitive sensor includes a first capacitor for providing an activation signal to the controller and a second capacitor for providing a deactivation signal to the controller.

31. A pump control for controlling a level of a liquid in a reservoir, the pump controller comprising:

a pump for being selectively activated to move the liquid out of the reservoir;

a power supply electrically connected to the pump for providing an alternating current to the pump when activated;

a sensor disposed at least partially within the reservoir for detecting the level of the liquid in the reservoir; and

a controller electrically connected to the sensor and between the pump and power supply, the controller obtaining the detected liquid level from the sensor when the alternating current of the power supply is at a zero-crossing to determine if the pump should be activated.

32. The pump controller of claim 31, wherein the controller determines when to activate the pump when a first liquid level is detected and determines when to deactivate the pump when a second liquid level is detected.

33. The pump control of claim 32, wherein the controller deactivates the pump after a run-time has expired, the run-time being determined when the second liquid level is detected.

34. The pump control of claim 32, wherein the controller deactivates the pump when the second liquid level is detected.

35. The pump control of claim 32, wherein the first and second liquid levels are detected by a capacitive sensor.

36. The pump control of claim 35, wherein the capacitive sensor includes a variable capacitor that provides a plurality of different capacitances with each capacitance corresponding to a different level of the liquid in the reservoir.

37. The pump control of claim 35, wherein the capacitive sensor detects a first capacitance for determining when the pump should be activated and a second capacitance for determining when the pump should be deactivated.

38. The pump control of claim 31, further comprising a sensor housing in which the sensor and controller are disposed;

and

a protective material disposed in the sensor housing to protect at least the controller from liquid.

39. The pump control of claim 38, wherein the protective material comprises a plurality of potting compounds having different properties.

40. A method of varying capacitance in a variable capacitor comprising:

providing a capacitor having a first electrode, a second electrode and a dielectric connecting the first and second electrodes to form a capacitor having a readable capacitance;

submersing at least a portion of the capacitor in a liquid, creating a liquid level with respect to the capacitor; and

changing the capacitance of the capacitor submersed in the liquid by increasing or decreasing the liquid level.

41. The method of claim 40 wherein the method further comprises encasing the first and second electrodes in the dielectric in order to avoid exposing the electrodes to the liquid.

42. A method of determining a level of liquid comprising:

providing a capacitor at least partially immersed in a liquid having a level that changes in relation to the capacitor, the capacitor having a variable capacitance depending on the level of liquid;

using a circuit connected to the capacitor to determine the capacitance of the capacitor; and

determining the level of the liquid based on the capacitance of the capacitor.

43. A method of operating a pump, comprising:

detecting a capacitance for a capacitor at least partially submerged in a liquid having a level that changes in relation to the capacitor, the capacitor having a plurality of capacitances with each capacitance corresponding to a different liquid level;

activating a pump when a first capacitance is detected;

determining when the pump should be deactivated when a second capacitance is detected; and

deactivating the pump as determined when the second capacitance was detected.

44. The method of claim 43, wherein determining when the pump should be deactivated comprises determining a run-time for the pump based on when the second capacitance was detected relative to when the first capacitance was detected or when the pump was activated.

45. The method of claim 44, wherein deactivating the pump comprises deactivating the pump after the run-time has expired.

46. The method of claim 43, wherein deactivating the pump comprises deactivating the pump when the second capacitance is detected.

47. The method of claim 43, further comprising;

providing an alternating current power supply to power the pump; and

detecting the capacitance of the capacitor at a zero-crossing of the alternating current power supply.

48. A method of operating a pump, comprising:

activating the pump when a level of a liquid in a reservoir reaches a first predetermined level;

detecting when the level of the liquid reaches a second predetermined level in the reservoir;

determining a run-time for the pump based on when the level of the liquid reached the second predetermined level relative to when the pump was activated or when the controller determines the pump should be activated, the run-time corresponding to how long the pump should be activated to move a predetermined amount of liquid out of the reservoir; and

deactivating the pump after the run-time passes.

49. The method of claim 48, further comprising using a sensor to detect when the level of liquid reaches the first predetermined level and the second predetermined level.

50. The method of claim 49, wherein the sensor is a capacitive sensor having a capacitor with a plurality of different capacitances, each capacitance corresponding to a different level of liquid being present in the reservoir, and the method further comprises using the sensor to detect when a first capacitance is reached corresponding to the first predetermined level of liquid being reached and when a second capacitance is reached corresponding to the second predetermined level of liquid being reached.

51. The method of claim 49, wherein the sensor includes first and second capacitive sensors and the method comprises using the first capacitive sensor to determine when the first predetermined level of liquid is reached and using the second capacitive sensor to determine when the second predetermined level of liquid is reached.

52. The method of claim 49, wherein the sensor includes a circuit board, the method further comprising dissipating heat from a component located on the circuit board with a heat sink.

53. The method of claim 52, further comprising positioning the heat sink below the liquid level.

54. The method of claim 52, wherein the component of the circuit board is a switching device, the method further comprising attaching the heat sink to the circuit board with the switching device, wherein the thermal metallization of the switching device is a thermal and mechanical bridge between the heat sink and the circuit board.

55. A method of operating a pump for controlling a level of a liquid in a reservoir, the method comprising:

providing an alternating current power supply;

detecting a level of the liquid in the reservoir at a zero-crossing of the alternating current power supply; and

activating the pump upon detecting the level of the liquid at a first predetermined level in the reservoir.

56. The method of claim 55, wherein detecting the level of liquid in the reservoir comprises using a sensor for detecting the level of liquid in the reservoir.

57. The method of claim 56, wherein the sensor is a capacitive sensor having a plurality of capacitances, with each capacitance being associated with a different level of liquid in the reservoir, the method further comprising detecting the level of the liquid by determining the capacitance of the capacitive sensor.

58. The method of claim 56, further comprising determining a run-time for the pump upon detecting the level of the liquid at a second predetermined level in the reservoir;

and

deactivating the pump when the run-time has expired.

59. The method of claim 58, wherein the sensor is a capacitive sensor having a plurality of capacitances, with each capacitance being associated with a different level of liquid in the reservoir, the method further comprising detecting the level of the liquid by determining the capacitance of the capacitive sensor wherein detecting the trigger signal from the sensor includes detecting a trigger capacitance from the capacitor of the sensor.

60. A method of manufacturing a capacitive sensor, comprising:

providing a circuit and a capacitor connected thereto which are operable to determine the level of liquid based on the position of the liquid with respect to the capacitor;

disposing a first protective material within a housing;

disposing the circuit and capacitor within the housing; and

disposing additional protective material within the housing.

61. The method of claim 60, wherein the first protective material is a potting compound, and disposing additional protective material within the housing comprises disposing a second potting compound within the housing different from the first potting compound.

62. The method of claim 60, further comprising connecting the capacitive sensor to a pump.

63. The method of claim 60, further comprising attaching the capacitive sensor to the housing of a pump.

64. The method of claim 60, further comprising disposing the capacitive sensor within the housing of a pump.

65. A dual pump system comprising:

a primary pump;

a capacitive sensor connected to the primary pump having first and second electrodes connected to a dielectric for sensing a level of a liquid and providing capacitance that varies with respect to the level of the liquid;

a secondary pump operable to be powered by a battery;

a transmitter operably connected to the secondary pump; and

a wireless receiver operable to receive information from the transmitter to alert a user of a status of the pump system.

66. A method of connecting a heat sink to a circuit comprising:

populating a circuit board with electronic components; and

reflow soldering the components to the circuit board, whereby a heat sink is connected to the circuit board via a switching device located on the circuit board.