Sensor system for measuring a velocity of a fluid including a heating element a resonant circuit and a transducer

• US 9,188,469 B2
• Filed: 10/15/2010
• Issued: 11/17/2015
• Est. Priority Date: 10/21/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Klee, Mareike, Haartsen, Jaap Roger
• Primary Examiner(s): Patel, Harshad R
• Application Number:
  US13/502,386
• Publication Number:
  US 20120210781A1
• Time in Patent Office: 1,859 Days
• Field of Search: None
• US Class Current: 1/1
• 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

A sensor system for measuring a velocity of a fluid flowing through a channel includes a heating element for heating the fluid. The heating element is provided with a predetermined level of power during operation. The sensor system further includes a primary electronic circuit having a primary resonance frequency which is temperature dependent. The temperature of the primary electronic circuit is determined by heat transferred from the heating element to the fluid flowing through the channel. In addition, the sensor system also includes a transducer arrangement configured to generate a measurement signal indicative of the velocity of the fluid flowing through the channel. The measurement signal is based on the primary resonance frequency.

Claims

1. A sensor system for measuring a velocity of a fluid flowing through a channel, comprising:

a heating element for heating the fluid, wherein the heating element is provided with a known level of power during operation;

a primary electronic circuit having a primary resonance frequency, wherein the 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 at least a part being responsible for making the primary resonance frequency temperature dependent; and

a transducer arrangement configured to generate a measurement signal indicative of the velocity of the fluid flowing through the channel, wherein the measurement signal is based on the primary resonance frequency,

wherein the primary electronic circuit comprises a resonant circuit including an inductor connected in series with a capacitor of the heating element, and wherein the capacitor has a capacitance that is dependent on temperature.

2. The sensor system according to claim 1, wherein the transducer arrangement comprises a grid dip oscillator configured to determine the primary resonance frequency of the primary electronic circuit.

3. The sensor system according to claim 2, wherein the heating element comprises a resistor configured to receive power via an inductive coupling with the grid dip oscillator.

4. The sensor system according to claim 1, wherein the primary electronic circuit is in thermal communication with the heating element.

5. The sensor system according to claim 4, comprising a reference electronic circuit having a temperature dependent reference resonance frequency, and wherein the transducer arrangement is configured to generate the measurement signal based on a numerical difference between the primary resonance frequency and the reference resonance frequency.

6. The sensor system according to claim 5, wherein the primary electronic circuit and the reference electronic circuit are substantially identical.