Thermal Sensor and Measurement Device Using the Same

• US 20070237206A1
• Filed: 06/28/2005
• Published: 10/11/2007
• Est. Priority Date: 07/15/2004
• Status: Active Grant

• Current Assignee: Mitsui Mining and Smelting Company Limited
• Original Assignee: Mitsui Mining and Smelting Company Limited
• Inventors: Tomonari, Kenji, Kubota, Akiko, Kawanishi, Toshiaki
• Granted Patent: US 7,934,868 B2
• Time in Patent Office: Days
• US Class Current: 374/164
• CPC Class Codes: B01D 2251/2067 Urea
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• CPC Class Codes: B01D 53/56 Nitrogen oxides B01D53/60 takes precedence
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: G01F 1/6842 with means for influencing the fluid flow
• CPC Class Codes: G01F 1/692 Thin-film arrangements
• CPC Class Codes: G01F 1/699 by control of a separate heating or cooling element
• CPC Class Codes: G01N 25/18 by investigating thermal conductivity by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18
• CPC Class Codes: G01N 27/18 caused by changes in the thermal conductivity of a surrounding material to be tested G01N27/20 takes precedence

Abstract

A thermal sensor in which, when an object to be measured is a water-based liquid, attachment of air bubbles to the external surface of the sensor is reduced to improve measurement accuracy. The thermal sensor has a sensing element (21a) including a heat producing body and a temperature sensing body, a resin mold (23) for sealing the sensing element (21a), and a heat transmission member (21c) for transmitting heat between the sensing element (21a) and a water-based object to be measured. A part of the heat transmission member (21c) is exposed from the resin mold (23) to form an exposed surface section. A hydrophilic film (50) formed of a silicon oxide film is applied to the exposed surface section and to that part of the surface of the resin mold which is positioned around the exposed surface section.

Claims

1. A thermal sensor comprising a sensing element including a temperature sensor, a resin mold that seals the sensing element, and a heat transfer member that performs heat transfer between the sensing element and a liquid to be measured, wherein a part of the heat transfer member is exposed from the resin mold to form an exposed surface portion, and a hydrophilic membrane is formed on the exposed surface portion.

2. The thermal sensor as set forth in claim 1, wherein the hydrophilic membrane is a silicon oxide film.

3. The thermal sensor as set forth in claim 1, wherein the hydrophilic membrane is formed on the surface portion of the resin mold located around the exposed surface portion of the heat transfer member.

4. The thermal sensor as set forth in claim 1, wherein the sensing element includes a heater.

5. A measurement device comprising the thermal sensor as set forth in claim 1 and a calculation section that calculates a characteristic value of the liquid to be measured based on the output of the thermal sensor.

6. The measurement device as set forth in claim 5, wherein a flow passage for the liquid to be measured which passes near the exposed surface portion of the heat transfer member is formed around the thermal sensor, the hydrophilic membrane is formed also on the surface portion of the member that constitutes the flow passage that faces the exposed surface portion of the heat transfer member.

7. The measurement device as set forth in claim 5, wherein the liquid to be measured is urea solution, and the calculation section is configured to calculate the urea concentration of the liquid to be measured.

8. The measurement device as set forth in claim 5, wherein the hydrophilic membrane is a silicon oxide film.

9. The measurement device as set forth in claim 5, wherein the hydrophilic membrane is formed on the surface portion of the resin mold located around the exposed surface portion of the heat transfer member.

10. The measurement device as set forth in claim 5, wherein the sensing element includes a heater.