MECHANISM FOR IMBALANCE RECOGNITION

The invention concerns a mechanism to the Umwuchterkennung at a turned part propelled over an electric motor. With most diverse machines of modern conception propelled over electric motor in constantly rising extent higher numbers of revolutions are used, which is valid insbesenders for example for s washing machines of modern conception regarding their highest Schleuderdrehzahl. After from Unwuehten in the propelled turned part, thus for example in the drum containing the laundry, resulting centripetal forces with the square of the number of revolutions rise, ever larger attention must in particular come with the nowadays partly schen realized Schleuderdrehzahlen of 1000 to 1400 and over it per minute to the Unwuchtkräften. Since e is economically hardly ne reinforcement for example the entire Schwingsystems of a washing machine vertrethar, must be getrachtet to keep as low the actually arising Unwuchtkräfte as possible. In this connection mechanisms of the kind initially specified are hekanntgeworden (S. e.g. DE-OS 8421845), with which at the antreihenden electric motor a Tacho are cultivated, that for the imbalance recognition over the speed fluctuations serves - with arising inadmissible Onwuchten, which can at lower numbers of revolutions to be determined to be able, then excavate on into the Schleuderdrehzahl is broken off. With the well-known mechanisms mentioned the relatively cost-intensive Tacho, which is age dependent also regarding assembly and maintenance an increased expenditure meant and beyond that in the usual remarks according to its permanent magnet runner temperaturund, is unfavorable. Task of the invention is it to improve a mechanism of the kind initially specified in such a way that existing Unwuchten of the turned part can be determined reliably and simply, whereby when the exceeding permissible imbalance values a further usable signal is to be made available. Still on the basis of the principle of the imbalance recognition over speed fluctuations in the drive system the task posed is solved during a mechanism of the kind mentioned in accordance with the invention thereby that in the voltage supply circle of the Elektremotors a resistance is attached arranged and to the entrance of an amplifier and that at the exit of the amplifier a filter capacitor is arranged, which is to the amplifier turned away connection because of its over a voltage divider at the signal input of a comparator, whose exit is connected with an evaluation unit. The resistance in the voltage supply of the electric motor is substantially more economical than the Tacho with the initially addressed well-known mechanisms and can be arranged with frequenzumriehtergesteuerten engines in the intermediate electric circuit and with commutator motors in the engine main stream circle. Over this resistance the river in form of the voltage drop, taken by the electric motor auf3S, is seized and supplied to the amplifier, which strengthens first the voltage drop from the current, so that at the exit of the amplifier DC voltage with an overlaid change portion is available, which represents proportional signal to the taken up current and thus the imbalance. From this signal afterwards the direct current is tert berausgefi]; the unwuehtsynchrone, remaining change on &fl part is supplied to the comparator and compared with its Sehaltsehwelle. The output signal of the comparator can be used then over the evaluation unit in order to break off for example in connection with the addressed use of the mechanism according to invention in a washing machine engine excavate on into the Sehleuderdrehzahl with exceeding of a certain limit value for the imbalance. &5 " the Sehaltschwelle of the comparator can be also adjustable in further arrangement of the invention, which makes the consideration possible for example from different numbers of revolutions or other external influences. In the latter connection it is in particular by advantage, if after a further arrangement of the invention for the default by speed-sensing trigger levels a Mikroso processor is intended, for what in a simple manner an increased safety against inadmissible Unwuchten when simultaneous utilization the speed-sensing differently large permissible Unwuchten made possible. The signal input of the comparator preferably multi-level, R-C-filters after another further training of the invention, can be upstream which the elimination of not imbalance-proportional change portions made possible and which Ansprechzuverlässigkeit of the mechanism increases. The exit of the comparator a R-C-filter can be downstream in further training of the invention, whose critical frequency is smaller than the imbalance frequency, which likewise improves the fail-safe characteristic of the mechanism. The invention is more near described in the following an' hand in the design in partial schematic diagram represented mechanism. As three-phase alternating current synchronous engine a trained electric motor --1-- is over voltage supply lines --2, 3, 4-- with a three-phase bridge --5-- connected, their two bridge legs in each case three power transistors --6-- exhibit, which in here not far racks way with the associated control for the production of the rotary field for the electric motor --1-- are connected. The actually conventionally trained and here not far interesting three-phase bridge --5-- becomes at the input side also over an electric rectifier --7-- arranged tension supplies; between the DC voltage exits of the electric rectifier --7-- is still another filter capacitor --7 '-- switched on. In the range of the power electronics left down is here a resistance switched on in the intermediate electric circuit of the frequency static frequency changer --8-- to recognize, that over lines --9, 10-- with that do not avertierenden (+) - entrance of an amplifier --11-- in connection is located. On the other hand is the resistance --8-- over the lower branch of the three-phase bridge --5-- at mass put. The inverting (-) - entrance of the amplifier --11-- lies over a R-C-combination --12-- at mass. The not inverting entrance of the amplifier --11-- still another two-stage filter consisting of two resistances and two Kendensatoren which are because of mass is 2S in the representation --13-- upstream, over only the low-frequency fluctuations at the resistance --8-- to let through sloping and the taken up current proportional tension. Also the R-C-combinations have the same task im übrigen --12-- (above already mentioned) and --14--. The amplifier --11-- is over lines --15, 16-- connected with mass and/or its supply voltage, whereby the line --16-- additionally still over a resistance --17-- with SO the exit --18-- is fed back. At the exit --18-- the amplifier --11-- a Gleichspannungssignal with an overlaid change portion is received in this way, which of the electric motor --1-- taken up river is proportional. The change portion of this signal is a direct measure for the imbalance working in the drive system, so that after the filter capacitor --19--, that the aperiodic component eliminated, the imbalance representing signal remains directly. This becomes over the voltage dividers --20-- - here trained as adjustable potentiometer - the not inverting (+) - entrance of the comparator --21-- supplied and there with a trigger level compared. According to the adjustableness of the voltage divider and/or. a border for the permissible imbalance size can be given to an equivalent adjustableness of this trigger level, also dependent on the intended final number of revolutions of the electric motor --1-- or other criteria to be made knows. The exit --22-- the comparator --21-- lies on the one hand over a resistance --23-- at a constant auxiliary tension and on the other hand over a diode --24-- and a R-C-filter --25-- at one here only schematiseh suggested evaluation unit --26--. The R-C-filter--25-- a critical frequency exhibits, which is smaller than the frequency, with which the imbalance measurement is accomplished, so that fail-safe characteristic is increased and when responding the comparator --21-- according to a without permission large imbalance of the evaluation unit --26-- a stable High signal is supplied. It is for the sake of completeness here mentioned that for example in connection with the use of the discussed mechanism with a washing machine the imbalance measurements for instance within the range of 1 to 2 cycles per second (related to the current - which corresponds to about 10 revolutions of the drum per minute) to be accomplished.