AIR FLOW RATE SENSOR ELEMENT AND ITS MANUFACTURE

摘要

PURPOSE:To reduce a heat movement quantity and make the response of the sensor element fast by forming the sensor element by using a heat generating resistance and a coating compound material so that the winding pitch of the heat generating resistance varies continuously while rough at a connection part and fine at the center part. CONSTITUTION:The sensor element has a heat generating resistance part and temperature measurement part formed of the heat generating resistance 1 made of a coiled platium wire and the coating compound material layer 3 made of glass and ceramic. The winding pitch of the platinum wire 1 is varied continuously so that it is rough at the connection part 21 and fine at the center part 31. In an operation state, such a temperature distribution that the quantity of heat generated with a current is low at a position close to a fixation part 21 and high at a distant part is obtained and the temperature measurement part measures mean temperature. Then if an air flow rate varies, control is so performed as to make the mean temperature of the whole heat generating resistance part constant; and the heat movement quantity is made small and the quantity of heat conducted to the fixation part is reduced to make the response of the sensor element fast.