DE1513867C

DE1513867C - Electric induction device with noise reduction

Info

Publication number: DE1513867C
Authority: DE
Inventors: Andrew Pittsfield Mass Glassanos (V St A )
Original assignee: General Electric Co
Current assignee: General Electric Co
Publication date: 1971-05-19

Description

Die Erfindung betrifft eine elektrische Induktionsvorrichtung mit Geräuschdämpfung, insbesondere kernlose Leistungsdrossel, mit einem zylindrischen Gehäuse, in dem eine Spule koaxial angebracht ist und das eine Tsoliermittelfüllung enthält, und mit einer den magnetischen Fluß in der Gehäusewand und außerhalb des Gehäuses stark reduzierenden Wirbel-Stromabschirmung in Form eines die Spule umgebenden, elektrisch gut leitenden, unmagnetischen Zylinders. ίοThe invention relates to an electrical induction device with noise attenuation, in particular Coreless power choke, with a cylindrical housing in which a coil is mounted coaxially and which contains an insulating agent filling, and with a magnetic flux in the housing wall and outside of the housing, strongly reducing eddy current shielding in the form of a coil surrounding the electrically conductive, non-magnetic cylinder. ίο

, Derartige Induktionsvorrichtungen sind durch die französische Patentschrift 1 324 797 bekannt. Kernlose Leistungsdrosseln sind ein extremes Beispiel für elektrische Tnduktionsvorrichtungen, bei denen der Fluß so stark nach außen streut, daß er große Wirbelstromverluste und eine gefährliche Erhitzung des magnetischen Materials des Gehäuses bewirkt, das die Vorrichtung aufnimmt. Es sind daher flußbegrenzende Wirbelstromabschirmungen verwendet worden, um die Größe des die magnetisierbaren Materialien der Gehäusewände erreichenden Flusses stark zu begrenzen. Derartige Abschirmungen werden gewöhnlich aus gut leitenden Materialien wie Kupfer und Aluminium hergestellt und sind gewöhnlich als Zylinder ausgebildet, die im Gehäuse zwischen der Spule und den Gehäusewänden angebracht sind. Materialien mit kleinem elektrischem Widerstand wie Kupfer und Aluminium sind jedoch relativ weich und flexibel, und Abschirmungen dieser Größe können schwierig in genauer Kreis- oder Zylinderform hergestellt werden. Die Wechselwirkung des Magnetfeldes mit den Wirbelströmen in der Abschirmung erzeugt mechanische Spannungen wechselnder Größe in der Abschirmung. und diese Spannungen bewirken eine Ausdehnung und Kontraktion der Abschirmung an verschiedenen Stellen, wodurch starke Schwingungen entstehen. Derartige Schwingungen werden sogar durch kleine Abweichungen des Abschirmquerschnitts von einem genauen Kreis sehr verstärkt. Unter der Annahme, daß die Exzentrizität der Abschirmung zu einer elliptischen Form führt, kann mathematisch gezeigt werden, daß cine Abschirmung mit einer Dicke von 1,25 cm und einem Radius von 130 cm, die von der Kreisform um 0,5 cm abweicht, mit einer Intensität schwingt, die 72mal größer ist als bei einer gleichen. (icnau kreisförmigen Abschirmung_v Such induction devices are known from French patent 1,324,797. Coreless power chokes are an extreme example of electrical induction devices in which the flux scatters outward so much that it causes great eddy current losses and dangerous heating of the magnetic material of the housing that houses the device. Flux-limiting eddy current shields have therefore been used in order to severely limit the amount of flux reaching the magnetizable materials of the housing walls. Such shields are usually made of highly conductive materials such as copper and aluminum and are usually designed as cylinders which are mounted in the housing between the coil and the housing walls. However, low electrical resistance materials such as copper and aluminum are relatively soft and flexible, and shields of this size are difficult to manufacture in an accurate circular or cylindrical shape. The interaction of the magnetic field with the eddy currents in the shield creates mechanical stresses of varying magnitude in the shield. and these stresses cause the shield to expand and contract in various places, creating strong vibrations. Such vibrations are even intensified by small deviations of the shielding cross-section from an exact circle. Assuming that the eccentricity of the shield leads to an elliptical shape, it can be mathematically shown that a shield with a thickness of 1.25 cm and a radius of 130 cm, which deviates from the circular shape by 0.5 cm, with vibrates at an intensity 72 times greater than the same. (icnau circular shield _v

F.s ist daher ersichtlich, daß in kernlosen Drosseln ein sehr großer Teil des Geräusches, das durch die Vorrichtung erzeugt wird, durch das Schwingen der Wirbelstromabschirmung verursacht wird. Bei derbekannten Vorrichtung ist zur Abhilfe schon vorgesehen worden, der Abschirmung eine von der Zylinderform abweichende Doppelkonus- oder faßartige Form zu geben und zusätzlich zwischen der Wirbelstromabschirmimg und der Gehäusewand eine Schwingungsisolalion in Form eines evakuierten Raumes oder einer Gasschicht oder eines anderen schwingungsdämpfenden Materials anzubringen. Dadurch werden die Kosten der Einrichtung beträchtlich erhöht, und es ist daher wünschenswert, das zu vermeiden.It can therefore be seen that in coreless chokes a very large part of the noise caused by the Device is generated by the oscillation of the eddy current shield is caused. With the known Device has already been provided to remedy this, the shield one of the cylindrical shape to give different double cone or barrel-like shape and in addition between the eddy current shielding and the housing wall a vibration isolation in the form of an evacuated space or a gas layer or other vibration-damping material to be attached. This will be increases the cost of the device considerably, and it is therefore desirable to avoid it.

Der l-rfmdunj', liegt die Aufgabe zugrunde, bei einer Iiuluktionsvorrichtung der eingangs genannten ArI, also mit einer den magnetischen Fluß in der zylindrischen Gehäusewand und außerhalb des Gehiiiises stark reduzierenden Wirbclstromabschirmung, fjleicli/citif.' den Aufbau des Gehäuses mit den die Geiinisrli(l.impliiMj· bewirkenden Teilen /u vereinfachen unil du Wir k^mikci! ilei ' icräu^chtf:iιτιp( 11 Mi· /11 ^r höhen. Dabei wird insbesondere angestrebt, irgendwelche Abschirmungen oder Schwingungsisolationen zwischen der Spule und der Gehäusewand zu vermeiden, desgleichen Geräuschpegelerhöhungen durch Verformen der zylindrischen, starken Kräfte ausgesetzten Wirbelstromabschirmung. Somit soll auch auf den Anbau frequenzabgestimmter Bauteile oder schalldämmender Mittel an der Gehäuseaußenwand weitgehend verzichtet werden können.The purpose of the l-rfmdunj 'is to provide an eddy current shielding that greatly reduces the magnetic flux in the cylindrical housing wall and outside of the housing in a cooling device of the type mentioned at the beginning. the construction of the housing with the parts causing the Geiinisrli (l.impliiMj · u. simplify unil du Wir k ^ mikci! ilei ' icräu ^ chtf: iιτιp (11 Mi · / 11 ^ r heights To avoid vibration isolation between the coil and the housing wall, as well as an increase in the noise level due to the deformation of the cylindrical eddy current shielding, which is exposed to strong forces.

Diese Aufgabe wird durch die gemeinsame Anwendung folgender Maßnahmen gelöst:This task is solved by the joint application of the following measures:

a) das Gehäuse besteht aus zwei topfförmigen Endabschnitten aus magnetisierbarem Material und einem mantelförmigen Zwischenabschnitt aus unmagnetischem, elektrisch gut leitendem Material; a) the housing consists of two cup-shaped end sections made of magnetizable material and a jacket-shaped intermediate section non-magnetic, electrically good conductive material;

b) die Spule ist so montiert, daß sie etwa zwischen den entgegengesetzten Enden des mantelförmigen Zwischenabschnittes liegt;b) the coil is mounted so that it is roughly between the opposite ends of the jacket-shaped Intermediate section is located;

c) der mantelförmige Zwischenabschnitt ist durch an seinen Enden angebrachte Ringflansche versteift, die mit den Ringflanschen der Endab- ,. schnitte Paare von Verbindungsflanschen bilden. i>c) the jacket-shaped intermediate section is stiffened by ring flanges attached to its ends, those with the ring flanges of the end,. cut pairs of connecting flanges. i>

Eine zweckmäßige Weiterbildung der erfindungsgemäßen Tnduktionsvorrichtung besteht darin, daß der mantelförmige Zwischenabschnitt durch ihn umschließende Versteifungsbänder aus unmagnetischem, elektrisch gut leitendem Material in seiner Zylinderform zusätzlich festgelegt ist. Damit wird sicher vermieden, daß der mantelförmige Zwischenabschnitt etwa in der Mitte zwischen seinen beiden Ringflanschen durch auf ihn einwirkende Kräfte die genaue Zylinderform verläßt und dadurch zu stärkeren Schwingungen angeregt wird.An expedient development of the induction device according to the invention is that the jacket-shaped intermediate section by means of stiffening strips made of non-magnetic surrounding it, Electrically good conductive material is additionally set in its cylindrical shape. This will surely avoid that the jacket-shaped intermediate section approximately in the middle between its two ring flanges leaves the exact cylindrical shape due to forces acting on it and thereby becomes stronger Vibrations is excited.

Durch die beanspruchte einstückige Ausbildung der Wirbelstromabschirmung mit der Gehäusewand wird eine derartige Festigkeit des Aufbaus erreicht, daß die Schwingung im Vergleich zu den bisher bekannten unabgesteiften inneren Wirbelstromabschirmungen bedeutend verringert wird. Durch diesen Aufbau werden Schwingungsisolationen zwischen der Wirbelstromabschirmun« und der Gehäusewand vermieden und überflüssig. Es ist natürlich möglich, den Geräuschpegel der Vorrichtung durch den Einbau eines schall- ( absorbierenden Materials um die Außenfläche des leitenden Tankwandabschnittes oder durch eine anders eingebaute Schallisolation um die Außenfläche der Abschirmung weiter zu verringern. Zum Beispiel kann der Zwischenabschnitt des Gehäuses doppelwandig sein, wobei der Zwischenraum zwischen den Wänden evakuiert oder anderweitig schallisoliert ist.The claimed one-piece design of the eddy current shield with the housing wall is such a strength of the structure achieved that the vibration compared to the previously known unsupported internal eddy current shields is significantly reduced. Through this structure will be Vibration isolation between the eddy current shield and the housing wall is avoided and superfluous. It is of course possible to reduce the noise level of the device by installing a sound ( absorbent material around the outer surface of the conductive tank wall portion or otherwise built-in sound insulation to further reduce the outer surface of the shield. For example the intermediate section of the housing can be double-walled, the space between the Walls evacuated or otherwise soundproofed.

Durch das deutsche Gebrauchsmuster 1 802 286 ist zwar schon eine Tnduktionsvorrichtung bekannt, die ein Gehäuse aus unmagnetischem Blech aufweist. Das Gehäuse kann dort durch den magnetischen Wechselfluß nicht zu Schwingungen angeregt werden, weil es ganz aus diesem Material besteht, jedoch wird dort nicht verhindert, daß der äußere Streufluß in der Nähe des Gehäuses liegende Eisenteile, z. B. Türen, zu Schwingungen anregen oder induktiv erwärmen kann. Zur Verhinderung eines größeren äußeren Streuflusses wird dort empfohlen, eine ferromagnetische Abschirmung zwischen der Spulenanordnung und der Kessclwand vorzusehen. Ferner ist dort auch schon auf schalldämmendc Mittel und eingeschweißte Verstärkungsstege an der Kcssclaußcnflächc hingewiesen. Die speziellen Probleme zylindrischer Wirbelstromabschirmungen sind dort nicht erwähnt.By the German utility model 1 802 286 an induction device is already known which has a housing made of non-magnetic sheet metal. The housing can there through the alternating magnetic flux will not be excited to vibrate because it consists entirely of this material, but will there does not prevent the external leakage flux lying in the vicinity of the housing iron parts, z. B. Doors, can stimulate vibrations or induce heating. To prevent a major exterior Flux leakage is recommended there, a ferromagnetic shield between the coil arrangement and the boiler wall. Furthermore, there is also already soundproofing means and welded-in Reinforcing webs on the Kcssclaußcnfläc pointed out. The special problems of cylindrical eddy current shields are not mentioned there.

Claims

3 43 4

From the magazine »VDE-Fachberichte« 1956, to close and also to limit the oscillation to a non-L, pages 124 to 129, it is also known to effectively limit the amplitude for trans-
formator housing preferentially oriented sheets less It can be seen that when operating magneto-magnetostriction or on the outside of the face see flux that is generated by the coil 10, through flexible additional walls, sound absorber from 5 no core of a magnetizable material behin rubber, Resonance oscillator or plate oscillator is changed and can be divided very strongly in the housing 13 with a phase shift of 180 ° to the interference. To be installed because of the electromagnetic imaging. Furthermore, due to the US shielding effect of the well electrically conductive intermediate patent specification 2 106 817, three-part cylindrical section 20, the greater part of this flow in the housing for coaxially installable coils is known, the housing of which is held. In the case of a larger power flow section, the diameter can be as that described here, but the housing section 20 consists entirely of ferromagnetic material of the housing section 20 and is one meter or more. carry. It can therefore be seen that the interactions

The invention is based on the kung in the drawing between the coil flux and the eddy currents

illustrated embodiments explained in more detail 15 men, which arise in the intermediate section 20, to be

will. It shows pregnant forces that cause tension in the

Fig. 1 is a side view, partially in section, causing intermediate section 20 and to Schwin-

an electrical induction device. This tendency to vibrate will

F i g. 2 shows a section along the line 2-2 in FIG. 2 through a small eccentricity or deviation of the

Fig. 1, and 20 section of exactly circular cross-section very

F i g. 3 is an axial partial section of a second conveyed out. As a result of the holding and stiffening

management form of the induction device. the effect of the end flanges 23, 24 and the

In the F i g. 1 and 2 is a coreless power stiffening band 25 but has the middle section

choke shown, which an electrical coil 10 on a sufficiently rigid structure so that the Schwin-

shows that the amplitude of the action between two separate supportive amplitudes is considerably smaller than that of the previous

Isolation spacers 11 and 12 and, within known, unstiffened inner shielding

a cylindrical housing 13 is mounted. The opposite is.

Housing 13 is essentially filled with a suitable, smaller vibrations of the intermediate section 20, insulation medium 14 such as oil or the like, so that the throttle housing continues to occur. Each of the coil 10 and its support structure are completely embedded in the medium or in vibration of that section. The insulating medium of any part of the housing causes the surrounding 14 to vibrate through a radiant cooler 15 in any air, thereby causing a ge in a conventional manner. The coil 10 is noisy, which can be more or less disturbing. In order to be provided with feed lines 10 α and 10Z), which further reduce the noise level, the upper side of the housing can be placed in isolation ducting 35 intermediate section 20 with sound insulation according to 16 and 17 to suitable external high and low levels . 3 are surrounded. As can be seen there, the voltage connections 16 have run α or YIa . such insulation an outer wall or a

The housing 13 consists of three axially curled cuffs 30 made of aluminum or some other isolated and adjacent sections, suitable metal, which have approximately the same axial extent as the intermediate section 20 and are electrically good at an intermediate section 20 Material such as copper or with the ring flanges 23 and 24 at the section 20 aluminum. In Fig. 1 is located which is connected to the cylinder. The intermediate section 20 and the drical intermediate section 20, the z. B. from aluminum outer cuff 30 so form a double wall, between two closed end ends middle housing section, the stiffening strips 25 are made between its cuts or covers 21 and 22, which are made of sheet steel 45 radially separated walls and the housing closures on the top - surrounds. Form the space between the middle and bottom. The three housing sections section 20 and the cuff separated therefrom are used at the opposite ends of the conductive 30, when it is evacuated or filled with a sound intermediate section 20 through interacting absorbent material, as sound insulation pairs of ring flanges 23 and 24 are connected to one another 50 _Z ur further reducing the vibrations that bound. Therefore, there is an annular flange 23 and is exposed to the surrounding air. In FIG Connection of the interacting flange material 31 such as glass wool or the like.
see at the end sections as well as for reinforcement 55
Reinforcement and stiffening of the otherwise flexible intermediate section made of aluminum. Patent claims:

In order to achieve a further reinforcement of the electrically conductive intermediate section 20, it is desirable to additional circumferential stiffeners between 60 1. Electrical induction device with see the ring flanges 23 and 24 to be attached. To noise attenuation, especially seedless Leidicsem The purpose is shown in FIG. 1 a number of external circuit throttles, with a cylindrical housing, Föimiger stiffening strips 25 shown, the in which a coil is mounted coaxially and the Surrounding intermediate section 20 and each of which contains an insulating material filling, and with one There are U-shaped aluminum supports that lead to a 65 the magnetic flux in the housing wall and exact circular ring was rolled. The stiffening outside of the housing greatly reducing tapes 25 are used to prevent an undesirable eccentric eddy current shielding in the form of a coil city in the cross section of the intermediate section 20 surrounding, electrically good conductive, non-magnetic

table cylinder, characterized by the joint application of the following measures:

a) the housing consists of two pot-shaped end sections (21, 22) made of magnetizable Material and a jacket-shaped intermediate section (20) made of non-magnetic, electrically highly conductive material;

b) the coil (10) is mounted so that it is approximately between the opposite ends of the jacket-shaped intermediate section is located;

c) the jacket-shaped intermediate section is stiffened by ring flanges attached to its ends which form pairs (23, 24) of connecting flanges with the ring flanges of the end sections.
2. Induction device according to claim 1, characterized in that the jacket-shaped intermediate section (20) is additionally fixed in its cylindrical shape by stiffening strips (25) surrounding it, made of non-magnetic, electrically highly conductive material.

1 sheet of drawings