DE1012760B - Electrical transducer for one adjustment path - Google Patents

Description

GERMAN

With many control devices, the problem is a desired position of an object to be adjusted precisely. For this purpose, transducers have become known, for example, which are in mechanical Control connection with potentiometers are, depending on the position of the object to be adjusted supply electrical voltage of the appropriate size. To bypass the mechanical scanning and the mechanical contacts are also contactless transducers, for example optical or capacitive ones Transducer, became known. These devices are neither a mechanical scanning element nor a have by this actuated electrical contact member, require a relatively high effort. Yet The effort is greater when the task is to generate a DC voltage that is according to size and Direction of an existing control deviation is proportional. The invention, on the other hand, treads one also known middle way in that a mechanical scanning element is retained, one displaced by this electrical contact device is avoided, however. Such a facility has proven to be proved to be advantageous, even if particularly difficult conditions of the measured value scanning are present, e.g. B. when sensing the slack of paper webs between two rollers or the like, and at the same time high requirements, such as high accuracy, high measuring speed and the like, to an associated control be asked.

The transducer according to the invention works in a manner known per se with one of an alternating voltage powered bridge circuit consisting of two series-connected secondary windings of a supply transformer, from an ohmic resistance as well as from an impedance, in particular a choke coil, with a contactless setting member which is in control connection with a scanning member for the adjustment path stands. According to the invention, a contactless, phase-sensitive one is attached to the output diagonal of the bridge Full-wave rectifier circuit connected, the output of which through the terminals of a the rectifier of the two-way circuit interconnecting resistor is formed and their AC supply voltage is also taken from the network supplying the bridge. The transducer According to the invention, at its output it provides a displacement which is proportional to the size and direction of the deviation from the nominal value of the specified displacement path DC voltage without any contacts or a constant reference voltage source Specification of the setpoint are required.

The invention is explained on the basis of the drawing using an exemplary embodiment. This is the main area of application, namely the through-electrical measuring transducer
for one adjustment path

Applicant:

Siemens-Schuckertwerke

Corporation,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Dipl.-Phys. Walter Engel, Nuremberg,
has been named as the inventor

slope measurement of a paper web 1 between two drums 2 and 3. The scanning element contains a dancer roller 4 which is pressed by a spring 5 against the paper web 1 running between the rollers 2, 3, 6 and 7. The roller 4 and the spring 5 are connected to the adjusting member 10 of a choke coil 11 via a linkage 8 which has a fixed point at 9. The adjusting member advantageously consists of a core part of the choke coil, through which the air gap is changed. It forms one A resistor of a bridge circuit, which also includes an ohmic resistor 12 and two series-connected secondary windings 13 and 14 of a transformer 15 connected to an alternating current network. Terminals 16 and 17 form the output of the bridge. They lead to a phase-sensitive full-wave rectifier circuit with two rectifiers 18 and 19, on the one hand to the center point 20 of a further secondary winding 21 of the mains transformer 15 and, on the other hand, to the center point 22 of one between the valves 18 and 19 Resistor 23. The terminals 24 and 25 of the resistor 23 represent the output of the transducer, at which one of the deviations of the sensed sag from a predetermined setpoint value is proportional DC voltage U in magnitude and direction. In order to achieve such a voltage, the bridge from the resistors 10 to 14 is balanced in such a way that a voltage of a predetermined mean phase position is present at the starting points 16, 17 at the specified nominal value. This means that the connections 24 and 25 of the full-wave rectifier circuit are de-energized. If the inductance of the choke coil 11 is caused by the deviation of the paper web 1 from the target position in one or the other direction

709 589/122

changed, the bridge becomes positive or negative detuned and in the full-wave rectifier circuit an alternating voltage of the corresponding phase position introduced. This creates at the terminals 24 and 25 of the resistor 23 the desired, the sought deviation from the nominal value of the sag of the paper web 1 according to size and direction corresponding DC voltage.

The device according to the invention can also be configured with a capacitor as a contactlessly adjustable impedance work. However, if the mains supply is 50 Hz, a choke coil is preferred. It's for that The invention continues to be irrelevant in what way the impedance used is changed in a contactless manner and what type of mechanical control connection used between the adjusting member of the Impedance and sensing element of the adjustment path is. Instead of a spring as a counterforce for the sensing element can also be a potential field, e.g. B. that of a magnetic field arrangement may be present.

20th

Claims (3)

Claims 1. Electrical transducer for an adjustment path, in particular for measuring the sag of paper webs between two drums or the like, with one of two connected in series Secondary windings of a transformer connected on the primary side to an alternating current network, from an ohmic resistance as well as from an impedance, in particular a choke coil, with a sensing element for the adjustment path existing bridge circuit, characterized in that on the output dagonal A contactless phase-sensitive full-wave rectifier circuit is connected to the bridge whose output is through the terminals of a resistor interconnecting their rectifiers is formed and their Speisewecfisel-, Voltage also from that feeding the bridge. Network is removed. 2. A transducer according to claim 1 with a choke coil in the bridge, characterized in that the choke coil is used as an adjusting member a parent part that changes an air gap of the same serves, the od via a push rod. Like., ζ. Β. by means of a dancer roller, preferably against the force of a spring or a potential field, " senses the adjustment path. 3. Transmitter according to claim 1 or ^^ at. characterized in that the AC bridges and the full-wave rectifier _{circuit are connected to Y ^ 1} ,, different secondary windings of the same mink * * transformer. ' Considered publications: German Patent No. 690 617; |! M. PfIier, »Electrical measurement of mechanical Yes; · ;, Sizes «1948, see pp. 64/65 and 70/71; | ΐ J. Krölert, "Measuring bridges and capacitors", ,, '* - 1935, Vol. I ₁ see p. 167 (Fig. 174), p. 202 (Fig. 232) ^!! and pp. 214/215. 1 sheet of drawings ■. ■■: ■: ■■: ■ *! ® TO 589/122 T.