Fluid sensing system

• US 6,335,690 B1
• Filed: 08/27/1999
• Issued: 01/01/2002
• Est. Priority Date: 01/15/1997
• Status: Expired due to Fees

• Current Assignee: Algonquin Scientific, LLC
• Original Assignee: Algonquin Scientific, LLC
• Inventors: Konchin, Boris, Corey, Randy W., Isakov, Slavik
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): Nguyen, Tai T.
• Application Number:
  US09/384,771
• Time in Patent Office: 858 Days
• Field of Search: 340/618, 340/450.2, 340/450, 340/620, 340/616, 340/623, 733/04.C
• US Class Current: 340/618
• CPC Class Codes: G01D 5/2073 by movement of a single coil with respect to two or more coils

Abstract

A fluid sensing system for monitoring a fluid parameter within a fluid container includes a fluid sensor and a fluid receiver. The fluid sensor is positioned at a first location and is operable to sense the fluid parameter. The fluid receiver is positioned at a second location remote from the first location and within proximity to the fluid sensor. The fluid receiver includes an amplifier having a feedback path. The amplifier is in a waiting non-oscillating mode when the fluid sensor is not electromagnetically coupled to the fluid receiver and in an active oscillating mode when the fluid sensor is electromagnetically coupled to the fluid receiver, such that feedback in the feedback path is one of either a substantially zero feedback and a negative feedback when the amplifier is a waiting non-oscillating mode and said feedback path is a positive feedback when said amplifier is in an active oscillating mode. This fluid sensing system is capable of monitoring various fluid parameters such as fluid level and fluid type within the fluid container.

Claims

1. A fluid sensing system for determining a fluid level within a fluid container, said fluid sensing system comprising:

a passive fluid level sensor positioned within the fluid container, said passive fluid level sensor operable to sense the fluid level within the fluid container;

a fluid level receiver in operative proximity to said passive fluid level sensor, said fluid level receiver operable to generate a signal indicative of the fluid level sensed by the passive fluid level sensor, said fluid level receiver having an amplifier with a feedback path, said amplifier being in a waiting non-scillating mode when said fluid sensor is not electromagnetically coupled to said fluid receiver and being in an active oscillating mode when said fluid sensor is electromagnetically coupled to said fluid receiver, wherein said feedback in said feedback path is one of either a substantially zero feedback and a negative feedback when said amplifier is in said waiting non-oscillating mode and said feedback path is a positive feedback when said amplifier is in said active oscillating mode; and

a fluid level indicator in communication with said fluid level receiver to provide a fluid level indication based on the signal generated by said fluid level receiver.

2. The sensing system as defined in claim 1, wherein said passive fluid level sensor includes a passive inductor/capacitor (LC) circuit.

3. The fluid sensing system as defined in claim 2, wherein a capacitance of said capacitor varies in proportion to the fluid level in the fluid container based upon a change in dielectric constant between parallel plates in said capacitor.

4. The fluid sensing system as defined in claim 3 wherein at least one of said parallel plates has an insulating layer to inhibit shorting between said parallel plates.

5. The fluid sensing system as defined in claim 3 wherein said parallel plates are geometrically configured to provide a substantially linear output relative to a shape of the fluid container.

6. The fluid sensing system as defined in claim 5 wherein said geometric shape is selected from the group consisting of a diamond shape, a triangle shape, and a barbell shape.

7. The fluid sensing system as defined in claim 3 wherein a communication channel between said passive fluid level sensor and said fluid level receiver is a wireless electromagnetic communication channel.

8. The fluid sensing system as defined in claim 1 further comprising a fluid type sensor operable to provide a signal indicative of a type of fluid in the fluid container based upon a change in the dielectric constant of the fluid.

9. The fluid sensing system as defined in claim 8 further comprising a fluid type receiver in operative proximity to said fluid type sensor, said fluid type receiver operable to generate a signal indicative of the fluid type.

10. A fluid sensing system for determining a fluid level within a fluid container, said fluid sensing system comprising:

a passive fluid level sensor positioned within the fluid container, said passive fluid level sensor operable to sense the fluid level within the fluid container;

a fluid level receiver in operative proximity to said passive fluid level sensor, said fluid level receiver operable to generate a signal indicative of the fluid level sensed by the passive fluid level sensor, said fluid level receiver includes a first inductor, a second inductor and an amplifier having a feedback path, said first inductor and said second inductor being positioned relative to one another so that upon creating an electromagnetic coupling between said first inductor and said second inductor when said passive fluid level sensor is not in operative proximity to said fluid level receiver, feedback from said coupling in said feedback path is one of either a substantially zero feedback and a negative feedback; and

a fluid level indicator in communication with said fluid level receiver to provide a fluid level indication based on the signal generated by said fluid level receiver.

11. The fluid sensing system as defined in claim 10 wherein said feedback in said feedback path is a positive feedback when said fluid level sensor is in operative proximity and electromagnetically coupled with said fluid level receiver.

12. A fluid sensing system for determining a fluid type within a fluid container, said fluid sensing system comprising:

a fluid type sensor operable to provide a signal indicative of a type of fluid in the fluid container based upon a change in the dielectric constant of the fluid, and

a fluid type receiver in operative proximity to said fluid type sensor, said fluid type receiver operable to generate a signal indicative of the fluid type, said fluid type receiver includes a first inductor, a second inductor and an amplifier having a feedback path, said first inductor and said second inductor being positioned relative to one another so that upon creating an electromagnetic coupling between said first inductor and said second inductor when said passive fluid type sensor is not in operative proximity to said fluid type receiver, feedback from said coupling in said feedback path is one of either a substantially zero feedback and a negative feedback.

13. A fluid sensing system for determining a fluid level and a fluid type within a fluid container, said fluid sensing system comprising:

a passive fluid level sensor positioned within the fluid container, said passive fluid level sensor operable to sense the fluid level within the fluid container;

a passive fluid type sensor positioned within the fluid container, said passive fluid type sensor operable to sense the type of fluid within the fluid container;

a fluid level receiver in operative proximity to said passive fluid level sensor, said fluid level receiver operable to generate a signal indicative of the fluid level in the fluid container, said fluid level receiver having an amplifier with a feedback path, said amplifier being in a waiting non-oscillating mode when said fluid sensor is not electromagnetically coupled to said fluid receiver and being in an active oscillating mode when said fluid sensor is electromagnetically coupled to said fluid receiver, wherein said feedback in said feedback path is one of either a substantially zero feedback and a negative feedback when said amplifier is in said waiting non-oscillating mode and said feedback path is a positive feedback when said amplifier is in said active oscillating mode;

a fluid type receiver in operative proximity to said passive fluid type sensor, said fluid type receiver operable to generate a signal indicative of the type of fluid in the fluid container; and

a fluid level indicator in communication with said fluid level receiver to provide a fluid level indication based on the signal generated by said fluid level receiver and said fluid type receiver.

14. The fluid sensing system as defined in claim 13 wherein said passive fluid level sensor includes a passive inductor/capacitor (LC) circuit and said passive fluid type sensor includes a passive inductor/capacitor (LC) circuit.

15. The fluid sensing system as defined in claim 13 wherein said passive fluid level sensor is in communication with said fluid level receiver, via a wireless electromagnetic channel and said passive fluid type sensor is in communication with said fluid type receiver, via a wireless electromagnetic channel.

16. The fluid sensing system as defined in claim 13 wherein said passive fluid level sensor and said passive fluid type sensor are formed from a pair of printed circuit boards separated from one another.

17. A fluid sensing system for determining a fluid level and a fluid type within a fluid container, said fluid sensing system comprising:

a passive fluid level sensor positioned within the fluid container, said passive fluid level sensor operable to sense the fluid level within the fluid container;

a passive fluid type sensor positioned within the fluid container, said passive fluid type sensor operable to sense the type of fluid within the fluid container;

a fluid level receiver in operative proximity to said passive fluid level sensor, said fluid level receiver operable to generate a signal indicative of the fluid level in the fluid container, said fluid level receiver includes a first inductor, a second inductor and an amplifier having a feedback path, feedback in said feedback path being substantially positive when said passive fluid level sensor is positioned in operative proximity to said fluid level receiver;

a fluid type receiver in operative proximity to said passive fluid type sensor, said fluid type receiver operable to generate a signal indicative of the type of fluid in the fluid container; and

a fluid level indicator in communication with said fluid level receiver to provide a fluid level indication based on the signal generated by said fluid level receiver and said fluid type receiver.

18. A fluid sensing system for sensing a fluid parameter within a fluid container, said fluid sensing system comprising:

a fluid sensor positioned at a first location relative to said fluid container, said fluid sensor operable to sense the fluid parameter, and

a fluid receiver positioned at a second location remote from said first location and within proximity to said fluid sensor, said fluid receiver having an amplifier with a feedback path, said amplifier being in a waiting non-oscillating mode when said fluid sensor is not electromagnetically coupled to said fluid receiver and being in an active oscillating mode when said fluid sensor is electromagnetically coupled to said fluid receiver, wherein said feedback in said feedback path is one of either a substantially zero feedback and a negative feedback when said amplifier is in said waiting non-oscillating mode and said feedback path is a positive feedback when said amplifier is in said active oscillating mode.

19. The fluid sensing system as defined in claim 18 wherein said fluid parameter is selected from the group consisting of fluid level and fluid type.

20. The fluid sensing system as defined in claim 18 wherein said fluid receiver further includes an input inductor in communication with an input to said amplifier and an output inductor in communication with an output of said amplifier, said input and output inductors being electromagnetically coupled to said fluid sensor when said receiver is in said active oscillating mode.

21. The fluid sensing system as defined in claim 18 wherein said fluid sensor includes a passive inductor/capacitor (LC) circuit.

22. The fluid sensing system as defined in claim 21 wherein a capacitance of said capacitor varies and an inductance of said inductor is fixed.

23. The fluid sensing system as defined in claim 21 wherein a capacitance of said capacitor is fixed and an inductance of said inductor varies.