| 摘要 |
<p>A hydraulic cylinder has an axial bore (43) formed in its piston rod (42). Shorted turn coils are wound on tubular formers (44 and 45) which are spigotted end to end into the bore (43) and which are spaced from either end of the bore (43). A probe projects into the axial bore (43) from the closed end of the cylinder casing (46). There are two drive coils (40 and 41) at the distal end of the probe. The length of each drive coil (40, 41) is no greater than the space between the shorted turn coils and the adjacent end of the bore (43). Hence each drive coil (40, 41) can move into and out of mutual induction with the shorted turn coils. The drive coils (40 and 41) are connected into external circuitry which is responsive to change of inductance of either coil (40, 41) and which is adapted to generate a reference signal upon the occurrence of preselected changing conditions of inductance of either coil (40, 41) caused by movement of that coil (40, 41) into or out of mutual induction with the shorted turn coils.</p> |
