GB999040A - Force transducers - Google Patents

Abstract

999,040. Measuring electrically. JOSEPH LUCAS (INDUSTRIES) Ltd. Sept. 29, 1961 [Oct. 20, 1960; May 12, 1961], Nos. 35942/60 and 17370/61. Heading G1N. [Also in Division H3] A pressure transducer includes a magnetic core comprising two resiliently interconnected parts between which pressure is to be applied, and an inductance coil associated with one of the parts to constitute a variable inductor forming part of an oscillator, whereby the oscillator frequency will depend upon the pressure between the parts. Ferrite core parts 9, 10 are secured respectively to a deformable member 8 and a fixed member 7, part 10 having a coil 11 forming part of an oscillator. In one embodiment (Fig. 2 not shown) coil 11 is connected in series with a capacitor and forms the secondary winding of a transformer, whose primary is connected in series with a tunnel diode across a resistor supplied with D.C. A pressurecalibrated measuring instrument is connected in series with the D.C. source. In a second embodiment (Fig. 3, not shown) a transistor oscillator is used. For zero-setting part 10 may be made adjustable by mounting it on a flexible plate 31 (Fig. 4) which can be deformed by adjusting screw 33, bearing against ball 32. Temperature compensation may be provided by mounting part 10 on a threaded stem which screws into a nut, which, in turn, screws in the opposite sense into member 7, the threads being of equal pitch. The stem is first adjusted at a first temperature to give a zero reading then it is fixed against further rotation by a washer having a projection fitting into a slot in the stem. The temperature is then raised or lowered and the nut is rotated until the zero reading is restored.