| 摘要 |
PURPOSE:To enable the detection of a moving body without fitting a permanent magnet to a body to be detected, by providing the moving body having a part to be detected which is prepared by applying ferromagnetic surface treatment to a non-magnetic body, and a magnetic sensor detecting the quantity of movement of the part to be detected or the presence of the movement thereof. CONSTITUTION:An inlet 3 and an outlet 4 of a flow channel 2 are formed in a casing 1. Fixed vanes 5 give a turning movement to a fluid flowing in the direction of an arrow. A spherical body 6 is located in a free state in the flow channel 2 in the rear of the fixed vanes 5, and is moved round in the direction vertical to the flow in the flow channel by the turning flow of the fluid. The spherical body 6 is formed of resin or the like, and the surface thereof is subjected to ferromagnetic surface treatment, whereby a part to be detected is formed. An outflow preventing body 7 serves to receive the spherical body 6 moving round. A magnetic sensor 8 is fixed, together with a permanent magnet 9 giving a magnetic field thereto, to the casing 1 by a fixture 10. A control circuit 11 processes a signal from the magnetic sensor 8.
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