| 摘要 |
1,162,128. Measuring rotational speed, electrically. KIENZLE APPARATE G. m. b. H. Dec. 7, 1967 [Dec. 15, 1966], No. 55735/67. Heading G1N. Correspondence between an indicated rotational speed value and an actual value measured by a tachometer (e.g. attached to a vehicle gear-box) is maintained by a circuit, as shown in Fig. 4. Tachometer 54 produces a D.C. voltage proportional to speed which is applied to a coil 57 on a core 55 energized with constant flux by a D. C. excited coil 56. A magneto-resistive plate 59 is located in an air-gap of the core and its effective resistance is connected in a bridge circuit which is balanced at zero speed. Flux produced by the tachometer voltage changes the magnitude of flux through plate 59 thereby changing its resistance, which unbalances the bridge. The resulting bridge output when amplified energizes a servomotor 62 which moves an indicator pointer, and simultaneously moves an armature core 63 in another air-gap, thus changing the reluctance of the magnetic circuit and hence the resistance of plate 59, until the bridge is rebalanced, when the pointer will indicate the correct speed value. The armature may be coupled to a recorder stylus. In an alternative embodiment Figs.2, 3 (not shown) there are two separate magnetic circuits, in the first of which the tachometer voltage controls the resistance of a first magnetoresistive plate and in the second movement of an armature coupled to the servomotor and indicator pointer controls the resistance of a second magneto-resistive plate. The resistances are connected in different arms of a bridge the unbalance voltage of which energizes the servomotor as before. In the embodiment Fig. 2 (not shown) the armature comprises two parallel relatively displaceable elongated tapered plates each having curved edges of paraboloid form. In Figs. 5, 6 (not shown) the armature comprises a pair of cam discs. Temperature dependent magneto-resistors may be utilized, to provide temperature compensation. |
