Untitled record

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AUSTRIAN

PATENT OFFICE

B Class: 21 C3 »046 Int.CE: H02H 005/04 © AT PATENTSCHRIFT © Nr. 354 548 © Patent owner: BBC AKTIENGESELLSCHAFT BROWN »BOVERI Ä CIE. BADEN SWITZERLAND © Subject: QREHiiBERTRAGER © Addition to Patent No.

© Elimination from: 241/76

Registered on: 1976 Ol 15 »2343/78 © Exhibition priority:

©©© Union Priority: SWITZERLAND (CH) 1975 01 17

588/75 CLAIMED © Start of patent duration: 1979 06 15 Longest possible duration:

© Issued on: 1980 01 10 © inventor:

© dependence:

354 548 © Pamphlets considered to delineate the prior art:

AT-PS 235429

No. 354548

The invention relates to a rotary transformer, in particular for transmitting information from a mechanically coupled to the rotor of the rotary transformer rotating machine part, with an annular rotor iron core, which faces an annular, separated by a radial air gap stator iron core coaxial, wherein in a section along the axis of rotation have the cross-sectional areas of the two iron cores, an L-shaped or U-shaped configuration, which complement each other substantially to an O-shaped cross-section, and with windings which are arranged in the annular space surrounded by the two iron cores.

Such a rotary transformer, however, for video signals and therefore for high-frequency signals, has become known from AT-PS no.235429. In this transformer are equal to each other opposite end faces of the legs of the U-shaped laminations of the rotor and the stator, with the axes of the legs are aligned. In order to avoid fluctuations in the coupling due to fluctuations in the air gap caused by manufacturing tolerances To reduce, is provided in the known transformer, not fully exploit the space limited by the web and the legs of the lamination winding space and to keep the near-web area of ​​each winding space free of windings.

With this measure, however, only the desired goal can be achieved if the determined by the mechanical structure of the entire system deviation in the direction of the axis of the transformer is very small, which is indeed the case with video systems.

In the transmission of signals from larger rotating machines, however, this condition is by no means given, which is why different transmission systems are used for such cases.

Thus, it is known to use in the context of the monitoring of machines with rotating parts, in particular with regard to their temperature systems contactless information transmission for the transmission of temperature values ​​from the rotating parts. Thus, the high-frequency transmission is known for it, which works with the help of, for example, antennas, coupling coils (damped oscillator) or coupling capacitors. However, all of these aforementioned devices operate at specific frequencies and require special measures to suppress information disturbing influences. Another known method is based on the impulse transmission by means of rotating magnets. However, the operation of this method is dependent on the position and speed of the rotating machine part to be monitored.

The object of the invention is to provide a rotary transformer of the type mentioned above, which is simple and inexpensive to manufacture and is insensitive to interference with changes in rotational speed and displacements of the rotor against the stator.

The invention solves this problem in that one or two legs of the cross section of an iron core with its free end edge or end edges of one or two edge portions of the cross section of the second iron core radially opposite, the axial extent or extent of those of the free end edge or exceeds the free end edges, wherein the outer corners of the free Stimrandes or end edges of the or the legs lie in the axial direction within the outer corners of the opposite edge portion or the edge portions of the cross section of the second iron core and are axially spaced therefrom at least by the amount of the maximum axial displacement of the rotor relative to the stator. From all these measures it can be seen that the manufacture of the rotary transformer can be carried out particularly simple and cost-saving, since relatively large tolerances can be allowed without resulting in interference in the signal transmission.

The latter is due to the fact that the air gap delimiting overlapping oppositely facing surface portions of the end faces of the rotor and the stator iron core remain the same size even with a shift and therefore results in virtually no change in the magnetic resistance for the magnetic flux.

As a significant advantage of the structure of the rotary transformer according to the invention is considered that axial and radial displacements of the rotating Teües against the fixed part of the machine to be monitored and thereby the rotor relative to the stator of the rotary transformer within limits, as they occur operationally in mechanical engineering, the operation of the rotary transformer or the measuring arrangement does not affect, what is to be noted that the rotary transformer according to the

No. 354548

Invention approximately occurring eddy currents have virtually no significance, since it works with inductions of only a few hundred Gauss and therefore the magnetic stresses are small. Due to the centric arrangement of the rotary transformer and no imbalance of the machine is possible. In addition, the rotary transformer is independent in its mode of action of the respective position and speed of its rotor, so there is no impairment of the transmission properties even with rotor standstill with intact arrangement

According to a further feature of the invention it is provided that the iron core of the stator with its axially parallel leg or web with serving as a housing part support sleeve and the iron core of the rotor with its axially parallel leg or flange also with a support sleeve or is connected to the shaft of the rotary transformer, wherein the substantially annular support sleeves have at least one end face an annular flange, whereby further simplifies the production of the transformer and a very simple way a mechanical protection for the laminated cores is achieved, in particular during assembly on or the dismantling of a rotating machine part is required. So can eg a puller be attached to the flange of the support sleeve. Furthermore, it is very useful if each support sleeve is glued to the respectively associated by iron bonded together by means of sheets metal sheets by means of synthetic resin. This makes it possible to connect both the sheets together and with the support sleeve in one operation. In addition, a very robust and solid construction is achieved.

In a modified embodiment of the rotary transformer is provided that the iron core of the stator and the iron core of the rotor is welded to the respective associated support sleeve, whereby a very high strength of the stator and the rotor can be achieved.

In particular, for transformers for high-speed machine parts, it is advantageous if the stator winding is glued to the iron core of the stator and the rotor winding with the iron core of the rotor by means of synthetic resin, since in this way a change in the position of the winding due to centrifugal forces and thus the emergence an imbalance is prevented. In addition, this also results in a mechanical protection for the winding through which the risk of wire breaks is reduced.

If particularly high demands are made on the quality of transmission, it is provided according to a further feature of the invention that the iron core of the stator and the iron core of the rotor consists of an annular pressed mass core of metal powder and synthetic resin or sintered material, which also has the advantage that the iron cores can be produced fully automatically.

For transformers with U-shaped sheet metal cross sections of the rotor and stator lamination packages, it is advantageous for reasons of saving tooling costs if the rotor lamination stack in each case has a trapezoidal cross section in the regions of the free ends of the radial limbs. In this case, it is possible to find the end with a punch that is adaptable through inserts for both the stator and rotor laminations.

In the drawings, several embodiments of the measuring arrangement according to the invention by means of an example of monitoring the winding temperature by means of temperature-dependent resistors in the rotor of an electric machine are shown in detail and described in more detail below. 2 shows an axial longitudinal section through a rotary transformer with L-shaped stator and rotor laminations and a threshold value device arranged in the rotor shaft, FIG. 3 shows a transformer variant in FIG Longitudinal center section with a part of the shaft to be monitored or 4a shows a transformer variant in axial section with a plug connection for the connection of the control device and in the axial direction on the shaft flange of the rotary transformer arranged threshold value device, Figure 4b shows the front view of the free side of the housing Drehübertragers, 5 shows the longitudinal center section of the threshold value device circulating with the rotor of the rotary transformer and the shaft of the machine to be monitored, and FIG. 6 shows a block diagram of the measuring arrangement according to the invention for a machine with at least one tuned part.

Fig.l shows the basic structure of the rotary transformer -1--. At the stationary part of the Drehübertragers -1- or separated from this, for example in a cabinet, a not in Fig.l not shown control unit -33- (Figure 6) is provided which has warning and release outputs. The effective iron of the stator -la- is made of U-shaped plates -2-. These sheets are made of synthetic resin

No. 354548 bonded to one another to form an annular stator laminated core -3--, wherein the stator laminated core -3-- is bonded to its cylindrical outer surface likewise by means of synthetic resin with a substantially annular support sleeve -4- surrounding the stator laminated core -3. This serving as a housing of the rotary transformer support sleeve -4- goes on at least one end face in an annular flange -5-- on, which holds the stator lamination -3- side. In the rotor of the rotary transformer open towards U-Profü the annular stator lamination -3- the stator winding -6- is arranged.

In the rotating part of the transformer - 1- is in Fig.l also not shown threshold value device -14- (Figure 6) is provided, for example, which is used as a sensor or Meßwertsignalgeber PTC thermistors in combination. The provided on one of the end faces of the rotor -7- connection points for the PTC thermistors or the connections of the circulating threshold value device -14- to the rotor winding -11- are also not shown.

The stator -la- included rotor --7-- has an analog structure as the stator -la- on. The effective iron of the rotor -7- is also made of U-shaped sheets by these are bonded together by means of synthetic resin to an annular rotor laminated core -8-. The rotor laminated core -8- is hiebei open with its U-profile to Statorblechpaket -3- and forms with its U-profile in the form of an O, wherein the air gap between the stator -la- and rotor -7- is designated by -12- , The rotor laminated core -8- is bonded to its axial cylindrical Freüassung also by means of synthetic resin with an annular support sleeve -9- merges at least one end face in an annular flange -10-, which holds the rotor laminated core -8- side. In the opposite to the stator -la- or the stator winding -6- rotating and open to this winding towards the U-profile of the rotor laminated core -8- the rotor winding -11- is arranged.

If it is necessary for reasons of strength, the stator laminated core -3- with its supporting sleeve -4- and the rotor laminated core -8- with its supporting sleeve -9- can be welded. The stator winding -6- and the rotor winding -11- are arranged concentrically with each other, wherein the stator winding -6- with the laminated stator core -3- and the rotor winding -11- with the rotor laminated core -8- is glued. The stator -la- of the rotary transformer - 1- is mounted on the bearing plate and the rotor -7- on the free shaft end of the machine to be protected. Speed ​​changes as well as axial and radial displacements of the rotor -7- relative to the stator -la-, as can occur during operation of electrical machines, have virtually no influence on the operation of the rotary transformer - 1-.

2 shows in an axial longitudinal section the basic structure of a Drehübertragervariante whose Fig.l corresponding part is referred to analog. The at least partially hollow shaft -13- of Drehübertragers -1- takes in the rotor -7- arranged threshold value device -14- on. The symbolically indicated magnetic flux in the effective iron of Drehübertragers -1- is designated with -15-, wherein the plates -16- of the stator -la- and the plates -17- of the rotor -7- in deviation from Fig.l L- are formed, whereby the insertion of the windings -6 and 11- is much easier.

Instead of sheets, the effective iron of Drehübertragers or its magnetic core and the core material, ie made of pressed MetaUpulver and synthetic resin or sintered material. At position -18- in particular the permissible axial displacement path between the stator and the rotor of the transformer is shown.

The connecting lines of the threshold value device -14- circulating in the rotor -7- with the rotor winding -11- and -20- the connecting lines of the stator winding -6- are labeled with the control device -33-.

In Figure 3, an assembly drawing of another rotary transformer variant is shown in axial section.

In this figure, the positions of Fig.l and 2 corresponding parts with the jeweüs same name have been adopted. On the housing -22- of Drehübertragers -1- is the housing -23- with the clamp disposed therein for connection of the control unit -33- (Figure 6). The L-shaped plates -16- of the stator are also secured by means of pressing rings -24- on the housing -22- and the L-shaped plates -17- of the rotor by means of pressing rings -24- on the WeUe -13-, whereby retaining rings - 25- are provided. The WeUe of the machine to be monitored is designated -26-. The rotary transformer -1- is free in its relation to the end of the Weu- 26-

No. 354548

Page completed by a cover -27--. The farther from the end cap -27-

End of the shaft -13- of the rotary transformer fits into a centrally arranged recess of the shaft -26- of the machine to be monitored, both shafts by means of screws -28- are interconnected. For easy assembly and disassembly of the rotary transformer - 1- are at the Ver⁵ Binding point of the waves -13 and 26- in the connecting lines -21- for the probe connectors -29- provided.

4a shows a further embodiment of a rotary transformer -1- shown in axial section, in which the rotating with the rotor -7- circulating threshold device -14- by means of a circuit connector -30- at the shaft end -26- the machine to be monitored facing ¹⁰ Shaft flange -31- of the transformer - 1- pluggable is arranged. Also in this figure, the positions corresponding to the positions of the previous variants are again denoted the same. For the connection of the stator -la- connected control unit -33- another connector -34- is provided. The shaft flange -31- of the rotor -7- is again by means of screws -28- on the

Shaft -26- attached to the monitored machine.

¹⁵ FIG. 4b shows the housing-side front view of the rotary transformer -1- according to FIG. 4a.

FIG. 5 shows the threshold value device -14- revolving with the rotor -7- according to FIG. 4a. The circuit plug -30- (see Fig.4a) is divided into the socket holder -35- with the multi-contact sockets -36- with hexagon nuts -37- and the pen holder -38- with the pins -39- together with the other hexagon nuts -40- on. The connecting cables of the pins -39- of the²⁰ the rotor -7- rotating threshold device -14- are designated -41-. The circuit of the threshold value device -14- is hiebei, as indicated in Figure 5, designed as an electronic circuit. The connecting lines of the electronics with the PTC thermistors serving as sensors are again named -21-.

From Fig.6 is the block diagram of the measuring arrangement for a machine with at least one ²⁵ rotating part with a rotary transformer -2, 16; 8, 17; 6, 11; 19, 20- can be seen, wherein the sheets of its stator -la- with -2 or 16- and the stator winding with -6- are designated. The stator winding -6- hiebei connected by means of connecting lines -20- to the separately and fixedly arranged control unit -33-, the one feed (zero, phase with eg 50 Hz) -50-, an output -51- for warning and an output -52- for tripping. The rotor core of the³⁰ Drehübertragers, however, is with -8- or its sheets are denoted by -17-. The rotor winding -11- is connected by means of connecting lines -19- to the circulating threshold device -14-. For the purpose of monitoring the temperature of the rotor winding, in particular of an electrical machine, by means of temperature-dependent resistors, the threshold device 14 has active circuit elements described below which are connected via the connecting lines -21- to two groups³³ of sensors, such as PTC thermistors -53 and 54- are connected. Of these two groups is used to detect that winding temperature at which an alarm is to be triggered, whereas the other group signal the switch-off or initiate the shutdown of the electrical machine to be protected. The two aforementioned groups of PTC thermistors can preferably consist of up to six individual PTC thermistors connected in series. Of course, let ⁴⁰ with appropriate circuit design of the threshold device -14- or control device -33- even more groups of Kaltleitem arrange for the detection of other temperatures.