GB862806A - Improvements in or relating to sizing devices - Google Patents

Abstract

862,806. Measuring electrically. DELAPENA & SON Ltd. July 16, 1959 [April 17, 1958; March 7, 1959], Nos. 12185/58 and 7984/59. Class 40 (1). [Also in Group XXIII] In a cylinder bore size indicating or controlling device the magnetic circuit of a coil is completed by a piece of magnetic material attached to the abrading head of a honing machine so that as the bore increases in diameter the reluctance of the magnetic circuit of the coil decreases. In Fig. 1 annular housing 1 holds cylinder liner 4 in honing jig 7. In an annular recess 10 is a U-section ring core 9 of magnetic material containing coil 12 held in place and protected from mechanical damage by a ring 14 of non-magnetic material. Sensing element, indicated at 31, is spring-mounted on the abrading head and urged into contact with the bore and tends to complete the magnetic circuit of coil 12 between the limbs of core 9. Preferably at least 3 sensing elements are used and the measurement obtained is of the mean bore diameter. Measuring circuit. The indication of bore diameter may be obtained by comparing the voltage developed across a fixed inductor, connected in series with the coil 12 across an A.C. supply, with a fixed proportion of the supply voltage. Alternatively, as in Fig. 2, the coil may be connected in series with a second similar coil not operatively associated with a bore, the voltages developed across each coil being rectified and applied to two coils of a differential relay 23 so that the difference in the two voltages operates the relay. A third winding 29 may be provided on the relay energized from a control voltage so that when the difference between the voltages developed by the operating coils 12 and 20 falls below a certain value the controlling winding operates the relay and stops the honing operation or indicates that the bore is the required size. The control voltage may be variable to cater for various nominal finished bore sizes. Alternative forms of core are suggested where the core does not completely encircle the bore possibly using two separate cores at each end of a diameter of the bore and preferably more than two sensing-elements so that at least one sensing element is always opposite each core and affecting the reluctance of its magnetic circuit.