Combination fluid sensor system

• US 8,978,450 B2
• Filed: 07/20/2011
• Issued: 03/17/2015
• Est. Priority Date: 07/22/2010
• Status: Active Grant

• Current Assignee: Watlow Electric Manufacturing Company
• Original Assignee: Watlow Electric Manufacturing Company
• Inventors: Steinhauser, Louis P., Lindley, Jacob, Paskvan, John
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): Frank, Rodney T
• Application Number:
  US13/186,916
• Publication Number:
  US 20120186334A1
• Time in Patent Office: 1,336 Days
• Field of Search: 73/617.6
• US Class Current: 73/61.76
• CPC Class Codes: F01N 11/00 Monitoring or diagnostic devices for exhaust-gas treatment apparatus , e.g. for catalytic activity safety, indicating or supervising devices for internal combustion engines F02B77/08; testing of machines G01M13/00
• CPC Class Codes: F01N 13/008 Mounting or arrangement of exhaust sensors in or on exhaust apparatus sensor arrangements for engine control F02D41/1439
• CPC Class Codes: F01N 2550/05 Systems for adding substances into exhaust
• CPC Class Codes: F01N 2560/06 the means being a temperature sensor
• CPC Class Codes: F01N 2560/12 Other sensor principles, e.g. using electro conductivity of substrate or radio frequency
• CPC Class Codes: F01N 2560/20 Sensor having heating means
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/1406 Storage means for substances, e.g. tanks or reservoirs
• CPC Class Codes: F01N 2610/142 Controlling the filling of the tank
• CPC Class Codes: F01N 2610/148 Arrangement of sensors
• CPC Class Codes: F01N 2610/1486 Means to prevent the substance from freezing
• CPC Class Codes: F01N 2900/1811 Temperature
• CPC Class Codes: F01N 2900/1814 Tank level
• CPC Class Codes: F01N 2900/1818 Concentration of the reducing agent
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: G01N 27/123 for controlling the temperature temperature control per se G05D23/00
• CPC Class Codes: H05B 2203/003 using serpentine layout
• CPC Class Codes: H05B 2203/01 Heaters comprising a particular structure with multiple layers
• CPC Class Codes: H05B 2203/013 Heaters using resistive films or coatings
• CPC Class Codes: H05B 2203/02 : Heaters using heating elements having a positive temperature coefficient
• CPC Class Codes: H05B 3/46 : heating conductor mounted on insulating base
• CPC Class Codes: H05B 3/82 : Fixedly-mounted immersion heaters
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

An apparatus for determining and controlling characteristics of a fluid is provided that includes a substrate, a heating circuit, and a sensing circuit applied on the substrate by a layered process. A control module is in communication with the heating circuit and the sensing circuit for determining, for example, type, concentration, liquid level, and temperature of the fluid, which in one form is a urea solution.

Claims

1. An apparatus for determining and controlling characteristics of a fluid comprising:

a substrate;

a heating circuit applied on the substrate for controlling characteristics of the fluid; and

a sensing circuit distinct from the heating circuit applied on the substrate for determining characteristics of the fluid;

wherein the heating circuit is applied on the substrate by a layered process comprising a first dielectric layer, a resistive layer and a second dielectric layer, and

wherein the sensing circuit is applied on the substrate by a layered process comprising a first dielectric layer, a conductive layer and a second dielectric layer.

2. The apparatus according to claim 1 wherein the layered process is selected from a group consisting of thick film, thin film, thermal spray, plasma spray, and sol-gel.

3. The apparatus according to claim 1 wherein the heating circuit has resistance which changes with temperature and is used for both heating and sensing temperature of the fluid.

4. The apparatus according to claim 1, wherein the fluid is a urea solution.

5. An apparatus for determining and controlling characteristics of a fluid comprising:

a substrate;

a heating circuit applied on the substrate for controlling characteristics of the fluid; and

a sensing circuit applied on the substrate for determining characteristics of the fluid;

wherein the heating circuit and the sensing circuit are applied on the substrate by a layered process and wherein the sensing circuit includes a pair of conductive pads for detecting one of electrical conductivity and dielectric constant of the fluid.

6. The apparatus according to claim 5 further comprising a control module that determines at least one of type, concentration, temperature, and level of the fluid based on output signals from at least one of the sensing circuit and the heating circuit.

7. The apparatus according to claim 6 wherein the control module determines concentration of the fluid based on the one of the electrical conductivity and the dielectric constant.

8. The apparatus according to claim 6 wherein the sensing circuit includes a plurality of conductive pads arranged in pair at a plurality of locations corresponding to a plurality of liquid levels.

9. The apparatus according to claim 8 wherein the control module determines the liquid level of the liquid solution based on the one of electrical conductivity and dielectric constant of the fluid and the locations of the conductive pads.

10. The apparatus according to claim 6 wherein the control module determines that the fluid level is below a threshold when resistance of the heating circuit exceeds a predetermined value after the heating circuit is energized for a predetermined period.

11. The apparatus according to claim 6 wherein the heating circuit includes a plurality of resistors corresponding to a plurality of levels.

12. The apparatus according to claim 11 wherein the control module determines the level of the fluid based a comparison of the resistance of the plurality of resistors after the plurality of resistors are energized for a predetermined period.

13. The apparatus according to claim 6 wherein the control module determines concentration of the fluid based on specific heat of the fluid.

14. The apparatus according to claim 5, wherein the sensing circuit comprises a first dielectric layer, a conductive layer and a second dielectric layer and the pair of conductive pads are expose through the second dielectric layer.

15. An apparatus for determining and controlling characteristics of a fluid comprising:

a probe section;

a layered heating circuit comprising a plurality of resistors arranged at a plurality of locations corresponding to a plurality of fluid levels formed on the probe section and having resistance that changes with temperature; and

a control module in communication with the heating circuit,

wherein the control module determines at least one of type, concentration, temperature and level of the fluid based on a change of the resistance of the layered heating circuit.

16. The apparatus according to claim 15 wherein the control module determines concentration and temperature of the fluid based on the change of resistance of the heating circuit after the heating circuit is energized for a predetermined period.

17. The apparatus according to claim 16 wherein the control module determines the level of the fluid based on a comparison of the resistance of the plurality of resistors after the plurality of resistors are energized for a predetermined period.

18. The apparatus according to claim 15 wherein the control module determines the level of the fluid when the resistance of the heating circuit exceeds a predetermined value after the heating circuit is energized for a predetermined period.

19. The apparatus according to claim 15, wherein the fluid is a urea solution.

20. The apparatus according to claim 15, further comprising a sensing circuit distinct from the heating circuit applied on the probe section for determining characteristics of the fluid.

21. A method of determining and controlling characteristics of a fluid comprising:

energizing a layered heating circuit having a plurality of resistors at a plurality of locations corresponding to a plurality of fluid levels;

determining a change of resistance of the layered heating circuit after the heating circuit is energized;

determining a level of the fluid based on the change of resistance of the layered heating circuit.

22. The method according to claim 21, further comprising determining that the fluid level is below a threshold when the resistance exceeds a predetermined value.