DE613742C - Centrifugal contact regulator for DC motors - Google Patents

Description

Centrifugal contact controller for DC motors to keep them constant the speed of electrical machines have become known regulators, their mode of operation in principle consists in that a; m circumference of a rotating disk is clamped Steel spring produces a contact at a certain speed, which on: corresponding Field resistances acts, so that an extremely high constancy of the speed is reached (Schmidt speed controller.).

The fineness of the regulation depends on the contact. Strong contact spark has a significant impact on accuracy as it changes the nature of the contact. In addition, metal migrations from the anode to the cathode occur because DC currents are interrupted. It is well known that silver is used as a contact material the metal migrations particularly strong; But that is what silver is for such regulators best material, since the surface conductivity is very high and already the lowest Giving touch a good contact.

Various precautions have now been taken to eliminate the deficiencies described. The direct current supplied to the centrifugal force contact has been converted into alternating current by means of a commutator; but here 'difficulties arise again because can occur in alternating strong sparking during the forming of the eligible direct currents.

In summary it can be stated that with regard to a high accuracy of the speed control, neither metal migration nor arcs occur to be allowed to.

While one at known facilities. the direct current through a Commutator feeds the centrifugal contacts, is according to the invention of the contacts AC current supplied is taken from the armature winding of the motor and used for field excitation formed via a commutator. In order to achieve a suitable contact voltage, the alternating current drawn from the armature via a transformer, its secondary winding is short-circuited by the centrifugal contacts, are fed to the commutator. If necessary, known means, such as capacitors, can be used to quench the spark at the contact and resistances, are applied.

An exemplary embodiment is shown in the figures. M is the DC motor with the excitation field F and an additional field Z. The additional winding Z leads to the brushes B on the commutator 1 <. At two points - the winding of the DC motor a,. b the alternating current is drawn; b leads to the one half ring of the commutator K, a via the primary winding p of the transformer T to the other Komrnutatorhalbring. The secondary winding s leads to contact J of the governor; If necessary, a resistor W can be connected in parallel with J. A transformer is interposed here to reduce the contact spark voltage. The transformer can of course be dispensed with in the case of low armature voltages; the centrifugal force contact will then, in the usual way, short-circuit part of the resistor which lies between armature winding tap a, b and commutator 1K. It would take the place of winding p in the circuit diagram, with contact J connected at its ends.

Of course, it is not necessary that the armature winding tapped at two diametrical points; one can do what is generally known, also tap winding parts, so that any voltages can be obtained.

The advantage obtained according to the invention lies partly in the simple arrangement of the commutator, which, as in known devices, no Intermediate lamellas with bridging resistors required in order to work without sparking, partly in the choice of the most favorable contact voltage.

Claims (1)

PATENTANSPRUCI3 Centrifugal contact controller for DC motors, thereby characterized in that the centrifugal contact controls the alternating current drawn from the armature and this, transformed by means of a commutator, is fed to the motor field.