| 摘要 |
<p>PURPOSE:To improve the response at the time of variation in air flow rate by making the trimming groove of the heat generating resistance body smaller in pitch at both end parts than at the center part of a temperature sensing element. CONSTITUTION:A platinum thin film 2 is adhered as a temperature dependent resistance film on the external surface of a cylindrical insulator 1 of alumina-based ceramic which has, for example, a 0.5mm external diameter, a 0.2-0.3mm internal diameter, and 2mm length, then a heat treatment is made, and the trimming groove 5 is formed by a laser. The trimming groove 5 is 10-20mum wide and formed spirally so that the groove pitch is 0.1mm at both end parts of the temperature sensing element consisting of the insulating pipe 1 and platinum thin film 2 and 0.2mm at the center part. Further, the temperature sensing element is connected to a lead 3 made of platinum-indium alloy by sintering with conductive paste 4 of platinum, etc. Further, the surface of the connection part between the temperature sensing element and lead 3 is coated with lead glass and baked. Consequently, the Joule heat at the end part of the temperature sensing element nearby the lead 3 is larger than that at the center part of the temperature sensing element, so the temperature distribution is uniformed and have a little variation against flow rate variation, thereby shortening the response time at the time of the flow rate variation.</p> |
