| 摘要 |
PURPOSE:To improve the reliability of flow rate detection by composing a detector of a magnetic rotating body which is rotated by flowing water, a magnetic sensor, and control circuits for them, and inserting a magnetic body made of a nonmetallic material with >=1 specific gravity by ferromagnetic surface treatment into the rotating body. CONSTITUTION:When fluid is flowed from an entrance 6 to an exit 7, it becomes a swivel flow at a fixed blade 8 to rotate a spherical rotating body 9 at a rotational frequency proportional to the flow rate in a flow passage, and a magneto-resistance element 11 detects the rotational frequency, which is processed by a control circuit 14 to calculate the flow rate. The rotating body 9 is formed by forming a ferromagnetic plating layer 16 on the surface of a relatively lightweight core sphere 15 having >=1 internal specific gravity and further covering its outside with a resin mold layer 17 having small specific gravity. Then, magnetic flux from a permanent magnet 12 changes in operating direction near the ferromagnetic rotating body 9 and the variation is detected by an element 7 from pulses. Consequently, wide-range flow detection is attained and abrasion and noise are reduced. |
