| 摘要 |
A linear transducer has an electrically conducting rod 5, mechanically connected to respond to the movement to be detected, which slides within an electrical winding 8 mounted on an insulating former 6. The winding 8 is connected as part of an LC circuit for an oscillator 24. As the rod 5 moves inwardly of the winding 8, eddy currents are induced in it by the energised winding 8 and reduce the inductive component of the electrical impedance of the winding. The resultant change in oscillator frequency is a measure of the movement to be detected. The transducer has an external metal casing 14. In order to prevent such eddy currents being induced in the casing 14 as to mask the effect of changes in eddy currents induced in the rod 5, the casing 14 is provided with means, such as an axially directed slit, which significantly increases the impedance of the eddy current paths within it. The slit may be sealed off by suitable electrically insulating material, so as to enable the interior of the transducer to be pressurised if a particular application requires this.
|
