| 摘要 |
<p>PURPOSE:To obtain a flow sensor being highly precise, having a temperature characteristic applicable over a wide range of an ambient temperature and being made small in size, by providing additionally a temperature-sensitive resistor for compensation of ambient temperature attached to a bridge circuit. CONSTITUTION:Temperature-sensitive resistors 1 and 1' are wound round in the shape of a coil on the outer periphery of a pipe and they are heated by a power from an electric current source 3. The resistors 1 and 1' form the sides of a bridge circuit respectively and outputs are made from the connection ends thereof to an operational amplifier 4. The resistor 1 is connected to the constant current sorce 3 and a fixed resistance 2. The resistor 1' is grounded and also connected to a fixed resistance 2', and the bridge circuit is formed of these components. Besides, a temperature-sensitive resistor 6 is connected in parallel to the resistances 2 and 2'. It is confirmed that a sensor current lowers necessarily with a rise in an ambient temperature when an output of the bridge circuit is fixed, that is, when a mass flow rate is under a prescribed condition. It is possible to change the sensor current by providing additionally the resistor 6 for compensation of the ambient temperature which is connected in parallel to the resistances 2 and 2' constituting the bridge circuit.</p> |
