DE1214891B - Inductive pick-up device - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

GOId

German class: 42 d- 1/12

Number:
File number:
Registration date:
Display day:

L45723IXb / 42d
August 30, 1963
April 21, 1966

The invention relates to an inductive tapping device using a current loop and a coil for inducing a voltage in the coil, its amplitude and phase of the relative The position of the coil depends on the current loop.

The invention consists in that the current loop crosses over in the manner of a figure eight with two partial loops is formed and with one in the one partial loop in the opposite direction of rotation as that of the current flowing through the other partial loop is applied and that the coil over the through the current loop limited areas is displaceable in the direction of the longitudinal axis.

An exemplary embodiment of the subject matter of the invention is shown on the basis of a drawing in FIG. 1 and 2 explained.

F i g. 1 shows the structure of the inductive tapping device while

F i g. 2 shows the course of the output voltage of this tapping device as a function of a path represents.

In Fig. 1, an electrical conductor forms one Loop 1. The insulated conductor is crossed like a figure eight, so that the entire loop consists of two partial loops. At one point the closed loop is interrupted and with connected to an alternator 4.

With 2 is a perpendicular to the loop plane and displaceable in the direction of the double arrow 7 referred to as ferromagnetic core. The loop plane lies between one leg and a yoke in an air gap of the core, so that the conductor with a longitudinal displacement of the core does not come into contact with this. A coil 3 is wound on said leg of the core, which is connected to a phase-rotating element 6 via movable leads. The exit of the phase-rotating element is connected to a rectifier, which is also of the Alternator 4 is affected.

The alternator drives a current i _p through the loop in accordance with the arrow directions drawn in the partial loops. As can be seen from the drawing, as a result of the crossing, one partial loop, viewed from above, flows through in a clockwise direction, while the current in the second partial loop runs counterclockwise. Accordingly, the magnetic fields that are generated in the two partial sole hoops have spatially opposite components. A part of the magnetic field is detected by the ferromagnetic core 2, the alternating flux being an inductive tapping device

Applicant:

Licentia Patent-Verwaltungs-G. m. b. H.,

Frankfurt / M., Theodor-Stern-Kai 1

Named as inventor:

Dipl.-Ing. Paul Seyfarth, Heiligenhaus

(District Düsseldorf)

induces a voltage in coil 3. Depending on the position of the core in relation to the current loop, predominates the field of the left or the right partial loop, or both fields stand out on the one in between Crossing point in the core. In the

The voltage induced by the coil 3 is applied to the phase-sensitive rectifier 5 controlled by the generator 4 after a phase rotation which takes the induction process into account.
A voltage U _A is established at the output of the rectifier, which according to FIG. 2 depends on the point χ at which the ferromagnetic core is in comparison to the current loop 1. At a point x, which is to the left of the crossing point x _k , a voltage is induced in the coil which, after phase rotation, should have the same phase as the control voltage of the generator 4. The output voltage U _{A of} the rectifier 5 is consequently positive. If the ferromagnetic core approaches the crossing point x _k , the output voltage U _A initially remains essentially constant, since the flux detected by the core changes only insignificantly. However, when the intersection point is closer, the influence of the field generated by the second partial loop becomes more noticeable in the core. Accordingly, the resulting alternating flux sensed by the core is reduced and a weaker voltage is induced in the coil. If the core is exactly at the crossing point x _k , then the field effects in the core cancel each other out, so that the output voltage U _A disappears at this point. If the ferromagnetic core is moved further to the right, the output voltage runs in the negative range, as previously described, since the magnetic field of the second partial loop predominates and a voltage is generated in the coil 3 that is 180 ° out of phase with the generator voltage .

609 559/189

The course of the amount of the output voltage U _A as a function of the path is influenced by the angle α at which the conductors of the current loop are crossed at the point x _k . The smaller the angle, the steeper the voltage curve at the zero crossing. The angle α reaches a minimum when the conductors are brought together in parallel at the crossing point. The scanning sharpness, i.e. the steepness of the output voltage curve, also depends on the strength of the core material used. The thinner the iron sheet or ferrite part used as the core, the greater the scanning sharpness. The scanning sharpness can also be changed by the position of the core in relation to the current loop. An inclination of the core causes an apparent widening of the cross-section, so that the scanning sharpness is reduced.

In a departure from the arrangement described, the loop 1 can also be completely closed. The current i " flowing through the current loop is then induced in the loop by a second, but fixed ferromagnetic core. The inducing magnetic field is generated by a coil attached to the core, which is connected to the alternating current generator 4. In addition, it is possible to provide the current loop with several crossing points, so that the circulating currents adjacent to each other in the partial loops flow in opposite directions. As a result, phase jumps and zero crossings of the voltage U _{A are} generated at each crossing point.

It is useful to place the coil 3, as shown in the drawing, on the one located at the air gap Apply legs so that the influences of any external fields are small. In addition, it is cheap when the frequency of the generator 4 is relatively high, so even with small magnetic field strengths relatively large voltages are induced in the coil.

It is particularly advantageous in this arrangement that the point λ ^ of the phase jump and the voltage zero crossing is independent of the exciting StromZp. Since, by the way, the place ^ very can be placed exactly at a previously determinable place and a high scanning sharpness can be achieved, the device is particularly suitable for scans in which small changes in path are measured should be.

The scanning device according to the invention is therefore particularly successful in arrangements for Force compensation and for measuring gauges, but also as a pointer handle for electrical measuring devices and Scales used.

Claims (2)

Patent claims: 1. Inductive tapping device using a current loop and a coil to induce a voltage in the coil, the amplitude and phase of which depends on the relative position of the coil to the current soleife, characterized in that the current loop (1) crosses over with two in the manner of a figure eight Partial loops is formed and is acted upon by a current (fp) flowing in the opposite direction of rotation in one part of the loop as in the other part of the loop, and that the coil (3) is bounded by the current base loop (1) in the direction of the longitudinal axis (x) is movable. 2. Inductive Abgriffsemrichtung according to claim 1, characterized in that the coil (3) is wound on a ferromagnetic core (2) provided with an air gap, in which the conductors of the current loop (1) can be moved. 1 sheet of drawings 609 559/189 4.66 © Bundesdruckerei Berlin