FR2483624A1 - Light, robust rotary electromagnetic indicator - opt. damped by ancillary rotor turning in silicone oil - Google Patents

Abstract

A galvanometer drive comprises an annular stator with a pair of internal radial teeth and twin windings which when energised induce an electromagnetic field at right angles to the diameter aligned with the teeth. A biplanar rotor supporting a pointer is deflected angularly relative to the radial teeth as a function of the field strength generated in the stator. The motion is damped by a rotor integral with the axial support for the polarised rotor but turning within a pot filled with a viscous fluid, pref. silicone oil. Compared with conventional galvanometer supports involving springs or torsion wires, the design is simple and robust, suitable for use in severe terminal or mechanical environments (aeronautics or military applications) and has a low mass relative to the strength of couple generated, e.g. 1 cN.cm per g.

Description

 The present invention relates to an indicator motor which can be used on measuring instruments and in particular on indicators of deviation of aircraft on-board instruments.

 This indicator can replace the magnetoelectric galvanometers previously used for this purpose.

 I1 has the particularity of having no supply and return spiral and therefore can be used in very severe thermal and mechanical environment conditions.

 In addition, its torque / angle gradient being very high, its resolution is very much higher than the conventional galvanometer.

 By its construction it is much more robust than a conventional galvanometer requiring pivots on point, a frame wound in very fine wire and fragile hairsprings.

 The torque-to-mass ratio is very high compared to a conventional galvanometer. Dens the realization the engine of the present invention has a mass of 1 gram for a couple of lcNecm. A conventional galvanometer has a mass of around 40 grartrues to obtain the same torque.

It includes Fig. 1 and 2
a) a stator constituted by a ferromagnetic toric armature 1, comprising one or two teeth 7 and 8. On this armature, a toroidal winding supplied with 4 and 5 creating a eye in the axis y 'y.

 b) a bipolar rotor 3 consisting of a diametrically magnetized disc, this disc is mounted on an axis supporting one indicator needle.

 c) a mechanical damper Fig. 2 comprising a stator 9 and a rotor 10, the damping being provided by a silicone oil between 9 and 10.

 The deviation information after amplification at A is applied in 4 and on the stator.

 In the absence of the signal in 4 and 5, the rotor aligns its axis of magnetization on x 'x, so as to close its field by the path of least reluctance, that is to say by the axis of the teeth stator.

 When a signal is applied in 4 and 5 a field is created on the y 'y axis.

Therefore, a torque is applied to the rotor. This torque is proportional to the intensity of the stator field for small angles. Under the effect of this dome, the rotor turns until the return torque balances the engine torque.

This restoring torque being proportional to the angle of rotation for small angles (+ 20 degrees), the angle of rotation of the rotor is proportional to the signal applied in 4 and 5.

 The direction of rotation depends on the polarity of the signal applied in 4 and 5.

 The engine which is the subject of the present invention may be used in indicators subject to the severe environmental conditions encountered in armaments and in aeronautics in replacement of the conventional fragile and heavy magnetoelectric galvanometers.

Claims (1)

CLAIMS a Indicator motor device usable in severe thermal and mechanical environment conditions, note E t in armament and aeronautics, characterized in that it consists of: a) a toroidal stator in ferromagnetic metal (1) comprising two diametrically opposed teeth (7 and 8), on which a winding is placed such that when it is supplied between its terminals (4 and 5) it creates a field oriented on the axis y'y perpendicular to the axis of the teeth ( 7 and 8). b) a bipolar rotor (3) consisting of a diametrically magnetized disc and supporting the indicator needle. c) a mechanical shock absorber.  2. Device according to claim 1 characterized in that the teeth (7 and 8) allow an inagnetic return and that the motor torque is proportional to the intensity of the field created by the stator for angles of plus or minus twenty degrees.  3. Device according to one of the preceding claims, characterized in that the mechanical damper comprises a stator (9) secured to the housing of the instrument and a rotor (10) secured to the rotor of the instrument, the damping being ensured by a silicone oil between the rotor (10) and the stator (9).