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A displacement transducer operable to measure relative displacement between two parts. The transducer comprises a shorted turn induction coil arrangement on one of the parts and, on the other part, a coaxial assembly of two drive coils separated by an output induction coil comprising two coils in qu

A displacement transducer operable to measure relative displacement between two parts. The transducer comprises a shorted turn induction coil arrangement on one of the parts and, on the other part, a coaxial assembly of two drive coils separated by an output induction coil comprising two coils in quadrature, the drive coils and the output induction coil being inductively linked with the shorted turn arrangement which may be two or more shorted coils end to end. The transducer is suitable for measuring displacement of a piston rod relative to its cylinder. The stroke and the bearing support of the piston rod may be such that either drive coil can project beyond the adjacent end of the intermediate induction coil arrangement at either end of the stroke. The consequent changing impedance of the drive coils can be used to set a datum for displacement measurement and/or control an electrically modulated control valve which controls operation of the cylinder. Cushioning of the piston rod at either end of its stroke and automatic continuous reciprocation of the piston within the cylinder can be provided as a result.

대표청구항 ▼

A displacement measurement device which is operable to measure relative displacement between two parts, the device comprising a pair of electrically similar drive coils and an output induction coil arrangement for mounting on one of the two parts, the drive coils and the output induction coil arrang

A displacement measurement device which is operable to measure relative displacement between two parts, the device comprising a pair of electrically similar drive coils and an output induction coil arrangement for mounting on one of the two parts, the drive coils and the output induction coil arrangement being substantially coaxial with the latter being located between the two drive coils which are spaced apart axially, and an intermediate induction coil arrangement for mounting on the other of the two parts substantially coaxially with the drive coils and the output induction coil arrangement mounted on said one part, the ends of the intermediate induction coil arrangement being short circuited, the device being arranged such that, in operation of it, the two drive coils are energized simultaneously by an applied alternating current signal so that alternating current flow is induced through the intermediate induction coil arrangement and through the output induction coil arrangement by the applied alternating current flow through the drive coils and by the induced current flow through the intermediate induction coil arrangement respectively, the current flow induced through the output induction coil arrangement serving as an output signal which is indicative of measured relative displacement between the two parts.