FR2514495A1 - CONNECTION INSTALLATION FOR OPERATING AND OPERATING A SHORT-CIRCUIT RING SENSOR - Google Patents

Abstract

A. CONNECTION INSTALLATION FOR THE OPERATION AND OPERATION OF A SHORT-CIRCUITED RING SENSOR. B. CHARACTERIZED IN THAT A SIGNAL GENERATOR IS PROVIDED TO PRODUCE A RECTANGULAR TENSION AND A TRINAGULAR TENSION VARIING WITH THE SAME FREQUENCY AND A COMPARATOR 4 IN WHICH THE VOLTAGE U PRODUCED IN THE SENSOR WINDING IS COMPARED WITH A VALUE OF SUM SHAPED WITH RECTANGULAR TENSION AND TRIANGULAR TENSION. C. INSTALLATION ALLOWING VARIOUS USES OF THE SENSOR.

Description

Connection installation for operation and exploitatic

  of a short-circuit ring sensor ".

  The object of the invention is to provide a device

  the operation and operation of a short-circuit ring sensor, in particular a single short-circuit ring sensor comprising a

  U-shaped or E-shaped iron core and a coil

  mounted on this core, the inductance of this winding

  can be modified by means of a short ring.

  circuit which surrounds one of the branches of the iron core and which is movable in the longitudinal direction of

  this branch according to a race to be determined.

  With such ring sensors in short circuit,

  there is a problem that during the operation

  the inductance of the ring sensor in short-circuit

  baked, an output quantity must be produced, in particular a current or a voltage, which is in the most linear relation possible with the displacement of the ring in short circuit and which allows a simple compensation of

the influence of temperature.

  The invention aims to avoid this difficulty

  and for this purpose concerns an installation of the type

  characterized in that there is provided a signal generator for producing a rectangular voltage and a triangular voltage varying with the same frequency and a comparator in which the voltage produced in the winding of the sensor is compared with a sum value formed with the rectangular tension and the triangular tension. The invention will be better understood with regard to the

  description below and accompanying drawings showing

  an exemplary embodiment of the invention, drawings in which: Figure 1 is a pulse diagram of the installation according to the invention;

  FIG. 2 is a diagram of the analogous

such an installation;

  Figure 3 shows an example of how

  of the digital part, with a micro-computer system

  of the installation according to the invention.

  The simple short-circuit ring sensor (EKR), not shown in detail, is operated with

  a current rising and falling in a rectangular way.

  The voltage UG at the sensor terminals varies in principle

  following the diagram shown in FIG.

  the voltage jump is proportional to the inductance, the slope is proportional to the active resistance of the

sensor coil.

  The VG voltage is compared in a comparator 4

  with a tension resulting from the superimposition of a

  triangular transition (VD) and a rectangular voltage (U R).

  This comparison voltage is expressed by

  UV =; e D R 'U and (;' being scaling coefficients

  The sign of X and r 1 depends on the input of the comparator (+ or -) to which the signal considered is applied by the switch S in FIG. 2. The time which elapses between a switching flank of the signal of output U Al of the comparator and a switching edge of the voltage UR constitutes a measurement of the inductance (L) and the active resistance (R) of the sensor and thus the

  position (X) of the ring in short circuit.

Description of the circuit:

  Operational amplifiers 1 and 2 constitute

  kill the signal generator This generator provides a rectangular voltage and a triangular voltage of the same frequency The triangular voltage UD controls the current source 3 which passes a triangular current in the sensor The voltage on the sensor is compared with the comparison voltage UV =: UD + ') UR in the

comparator 4.

  The weighting of the three voltages UG, UD and UR

  is carried out with a (passive) network of

  taking the resistors Ri, R P, RG and RD

  The sign of ck and C is determined by the posi-

  S switch (multiple switch or contact bridge) With the resistors Rp 4, R (, RG and%, the characteristic and the gradient of the

temperature variation.

  The phased or analogous duration circuits are mostly used in

  a microcomputer system (kt C) So we broke up

  thought to indicate a special logical mount for the

  further processing because this

  the microcomputer used (,} k C).

  FIG. 3 represents an operating circuit according to the invention: the kb C takes the digital measurement values of an external meter and recalls the

  counter As a counting signal, we can take

  the basic cadence of "C To have a definition

  sufficiently precise, the frequency of accounting must be

  ge is between 1 and 4 M Hz. If the recall is not performed until after each nth period (to eliminate

  the frequency of counting may be lower

accordingly.

  The installation according to the invention has the following advantages: possibility of easy exchange in the "C" systems,

  temperature compensation without additional

  the use of EKR sensors, the smaller size of the sensor, the sensor has only two connections,

  possibility of easy intervention on the characteristic

  that and the temperature coefficient by an appropriate choice of the frequency of the supply signal and by the position of the comparison voltage,

  automatic compensation for fluctuations in the

  power supply, simple construction: just a quad operational amplifier, noise elimination by averaging (with an average over N periods, the counter of figure 3 is only recalled after each nth period) ,

  simple delay offset compensation (

  monostable tribulator or flip-flop) at the output 2: The additional offset of the sensors KR (that is to say that for X = 0, the output signal is <0), can be eliminated by a delay at the output 2 ( it can also, of course, be suppressed by subtracting a constant in-the C), one can have ascending characteristics or

descending characteristics.

Claims (1)

R E V E N D I C A T I O N   Connection installation for the operation and operation of a short-circuit ring sensor, comprising a winding whose inductance can be modified by moving the ring in short-circuit, characterized in that it is provided a signal generator for   produce a rectangular voltage and a triangular voltage   varying with the same frequency and a comparator   (4) in which the voltage (UG) produced in the winding   the sensor is compared with a sum value   formed with the rectangular tension and the gular.