SENSOR SYSTEM FOR MEASURING A VELOCITY OF A FLUID

• US 20120210781A1
• Filed: 10/15/2010
• Published: 08/23/2012
• Est. Priority Date: 10/21/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Klee, Mareike, Haartsen, Jaap Roger
• Granted Patent: US 9,188,469 B2
• Time in Patent Office: Days
• US Class Current: 73/204.23
• CPC Class Codes: G01F 1/688 using a particular type of heating, cooling or sensing element G01F1/6847 takes precedence
• CPC Class Codes: G01F 1/6882 making use of temperature dependence of acoustic properties, e.g. propagation speed of surface acoustic waves
• CPC Class Codes: G01F 1/696 Circuits therefor, e.g. constant-current flow meters
• CPC Class Codes: G01F 1/6986 with pulsed heating, e.g. dynamic methods
• CPC Class Codes: G01F 1/699 by control of a separate heating or cooling element

Abstract

The invention relates to a sensor system (102) for measuring a velocity of a fluid (110) flowing through a channel (108), comprising a heating element (104) for heating the fluid, wherein the heating element (104) is provided with a predetermined level of power during operation. The sensor system (102) furthermore comprises a primary electronic circuit (114) having a primary resonance frequency, which primary resonance frequency is temperature dependent. Herein the temperature of the primary electronic circuit (114) is determined by heat transferred from the heating element (104) to the fluid (110) flowing through the channel (108). In addition, the sensor system (102) comprises a transducer arrangement (126) configured for generating a measurement signal (128) indicative for the velocity of the fluid (110) flowing through the channel (108). Herein, the measurement signal (108) is based on the primary resonance frequency.

Claims

1. A sensor system (102, 202, 302, 402) for measuring a velocity of a fluid (110, 210, 410, 510) flowing through a channel (108, 208, 408, 508), comprising:

a heating element (104, 204, 304, 404, 504) for heating the fluid, wherein the heating element is provided with a known level of power during operation,

a primary electronic circuit (114, 214, 414, 514) having a primary resonance frequency, which primary resonance frequency is temperature dependent, wherein a temperature of at least a part of the primary electronic circuit is determined by heat transferred from the heating element to the fluid flowing through the channel, said part being responsible for making the primary resonance frequency temperature dependent,

a transducer arrangement (126, 226, 422, 522) configured for generating a measurement signal (128, 228, 424, 524) indicative for the velocity of the fluid flowing through the channel, wherein the measurement signal is based on the primary resonance frequency.

2. The sensor system according to claim 1, wherein the transducer arrangement comprises a grid dip oscillator (130, 230, 4) for determining the primary resonance frequency of the primary electronic circuit (114, 214, 414, 514).

3. The sensor system according to claim 2, wherein the heating element (204) comprises a resistor (212) for receiving power via an inductive coupling with the grid dip oscillator (230).

4. The sensor system according to claim 1, wherein the primary electronic circuit (114, 214) comprises an inductor (118, 218) and a capacitor (116, 216) in series connection, and wherein the capacitor has a capacitance that is dependent on temperature.

5. The sensor system according to claim 1, wherein the primary electronic circuit (114) is in thermal communication with the heating element (104).

6. The sensor system according to claim 5, wherein the heating element (104) comprises the capacitor (116).

7. The sensor system according to claim 5, comprising a reference electronic circuit (120, 420) having a temperature dependent reference resonance frequency, and wherein the transducer arrangement (126) is arranged for generating the measurement signal (128) based on a numerical difference between the primary resonance frequency and the reference resonance frequency.

8. The sensor system according to claim 7, wherein the primary electronic circuit (114) and the reference electronic circuit (120) are substantially identical.

9. The sensor system according to claim 5, comprising a secondary electronic circuit (220) having a temperature dependent secondary resonance frequency, wherein the primary electronic circuit and the secondary electronic circuit are situated at predetermined locations on opposite sides of the heating element (204) along an axis (225) having a component parallel to a longitudinal axis of the channel, wherein the transducer arrangement (226) is arranged for generating the measurement signal based on a difference between the primary resonance frequency and the secondary resonance frequency and wherein the primary electronic circuit and the secondary electronic circuit are in thermal communication with the fluid (210).

10. The sensor system according to claim 5, comprising a secondary electronic circuit (220) having a temperature dependent secondary resonance frequency, wherein the primary and secondary electronic circuits are situated at predetermined locations on opposite sides of the heating element (204) along an axis (225) having a component parallel to a longitudinal axis of the channel, wherein the transducer arrangement (226) is arranged for generating the measurement signal based on a difference between the primary resonance frequency and the secondary resonance frequency, and wherein the primary electronic circuit and the secondary electronic circuit are in thermal communication with the heating element (204).

11. The sensor system according to claim 9, wherein the primary electronic circuit (214) and the secondary electronic circuit (220) are substantially identical.

12. The sensor system according to claim 5, comprising:

a reference electronic circuit (120) in thermal communication with the heating element (404) and having a reference resonance frequency, and

a secondary electronic circuit (220) in thermal communication with the fluid (410) and having a secondary resonance frequency,

a further electronic circuit (414) in thermal communication with the fluid and having a further resonance frequency,

wherein the primary, the secondary, the further and the reference electronic circuits are substantially identical, wherein the secondary electronic circuit and the further electronic circuit are situated at predetermined locations on opposite sides of the heating element along an axis (416) having a component parallel to a longitudinal axis of the channel (408), and wherein the transducer arrangement (422) is configured for generating the measurement signal (424) based on a ratio of the numerical difference between the secondary resonance frequency and the further resonance frequency and the numerical difference between the primary resonance frequency and the reference resonance frequency.

13. The sensor system according to claim 1, comprising a power source (512) configured for providing the heating element (504) with a time varying level of power, wherein the primary electronic circuit (514) is situated at a predetermined distance from the heating element (504) along an axis (520) having a component parallel to a longitudinal axis of the channel (508), wherein the primary electronic circuit is in thermal communication with the fluid (510), and wherein the transducer arrangement (522) is configured for generating the measurement signal (524) based on the duration after which the primary resonance frequency changes in response to the time varying level of power.

14. The sensor according to claim 13, wherein the power source (512) is configured for providing the heating element with a power pulse.

15. The sensor system according to claim 13, wherein the power source (512) is configured for providing the heating element with a sinusoidally varying level of power.