EP2304744A1

EP2304744A1 - Inductance coil for electric power grids having reduced sound emission

Info

Publication number: EP2304744A1
Application number: EP09771828A
Authority: EP
Inventors: Alexander Grisenti; Josef Eder; Johann MÜLLEDER
Original assignee: Coil Holding GmbH
Current assignee: Coil Holding GmbH
Priority date: 2008-06-30
Filing date: 2009-06-30
Publication date: 2011-04-06
Anticipated expiration: 2029-06-30
Also published as: AT507928B1; WO2010000005A1; BRPI0913649B1; AT507928A1; EP2304744B1; US8339234B2; CA2729020A1; AT507024A1; CA2729020C; US20110115601A1; EP2304744B2; CN102203888B; HK1161416A1; BRPI0913649A2; AT507024B1; CN102203888A

Abstract

The invention relates to an inductance coil, particularly an inductance coil without iron core for use in electric power grids, comprising at least two cylindrical winding layers (1), which are disposed concentrically with respect to a coil center line (7) and are connected electrically in parallel. Said inductance coil comprises at least one means for reducing or minimizing sound emissions developing during operation of the inductance coil. At least the outermost winding layer (1) is designed as a current-conducting, acoustic shield winding (18) with respect to the winding layer (1) adjoining in the direction of the center line (7), wherein said shield winding (18) is dimensioned electrically such that it is designed for the transmission of a current intensity which is only a fraction of the current intensity which is to be transmitted by the adjoining winding layer (1). The invention further relates to a clamp-like retaining element disposed on at least one face end of the inductance coil for reducing sound emissions.

Description

Choke coil for electrical energy supply networks with reduced noise emissions

The invention relates to a choke coil, in particular a choke coil without iron core for use in electrical power supply networks, with at least two cylindrical, with respect to a coil center axis concentrically arranged and electrically connected in parallel winding layers, and at least one means for reducing or minimizing during operation of the choke coil resulting acoustic emissions, as indicated in claim 1 or 18.

In coils, especially in dry-insulated inductors without iron core with two or more, leaving crevices, concentrically arranged inside each other, electrically connected in parallel cylindrical winding layers, it is known to wind the winding layers of rectangular shaped conductors or conductor bundles, wherein the winding layers different, predominantly have decreasing number of turns from inside to outside. The basic structure of concentrically arranged one inside another, electrically connected in parallel winding layers is known from the prior art, for example, the European patent EP 0 092 018 Bl.

Figures 1 and 2 show the basic structural design of such

Winding layers 1 and thus constructed coil windings. The winding layers 1 arranged concentrically in one another about a common coil central axis 7, which are made of substantially rectangularly shaped conductors or conductor bundles 6, are held together by holding elements 2 at the coil ends, for example so-called winding stars made of metal or plastic. Usually, those in the two distal ones

End portions of the coil arranged holding elements 2 via a clamping structure, for example, held together by a plurality of tension members 3 made of impregnated glass fibers, which are mounted along the winding. Between the holding elements 2 and the coil or winding ends are usually especially when the holding elements 2 are electrically conductive, insulation elements 4 attached. The concentrically nested winding layers 1 are in the radial direction preferably by further insulation elements 5, for example, electrically insulating gap strips, distanced to produce vertical gaps for the natural air cooling of the entire reactor winding. To what extent head or conductor bundles 6 are used from several insulated individual conductors, depends on the expected eddy current losses, which are to be kept within economic limits.

The number of turns of the winding layers 1 and the electrical coils to be manufactured are determined so that both the desired inductance is achieved and the desired current and operating temperature distribution via the parallel winding layers 1 - see FIG. 1 - is achieved. With this requirement, there are different numbers of turns decreasing predominantly from the inside to the outside for the winding layers 1 connected electrically in parallel.

A possible uniform axial voltage gradient in all winding layers 1 and thus the avoidance of significant voltage differences between the opposing turns of adjacent winding layers 1 is ensured by achieving equal heights or equal axial lengths of the individual winding layers 1, ie by maintaining the same possible axial winding layer heights H. This is achieved by adapting the height GH1, GH2, GH3 of the conductor or conductor bundle 6 measured in the axial direction of the winding layers 1 to the different numbers of turns of the winding layers 1 connected in parallel. The measured in the axial direction of the winding layers 1 height GHl, GH2, GH3 of the conductor or conductor bundle 6 in the individual winding layers 1 is also referred to as a pitch, which defines the dimension of the conductor or conductor bundle 6 in the direction of the winding or coil axis. Due to the number of turns predominantly decreasing from the inner winding layers 1 to the outer winding layers 1, the conductors or conductor bundles 6 in the outer winding layers 1 have larger dimensions in the axial direction. In particular, the conductors or conductor bundles 6 of the outer winding layers 1 in a direction parallel to the Spulenlängs- or Spulenmittelachse 7 greater heights GH 2, GH3, as the heights GHL the conductor or conductor bundle 6 of the inner winding layer 1 of the coil.

The adaptation of the axial height GH1, GH2 or GH3 of the conductor or of the conductor bundle 6 to the respectively required conductor or conductor bundle 6 with an approximately or largely rectangular cross-sectional shape is achieved by pressing a round conductor or a cable-shaped conductor material. According to the determined in the course of electrical or thermal design of the inductor coil numbers for the concentrically arranged winding layers 1, the required dimensions of the conductors or of the conductor bundles 6, in particular the aforementioned pitches GH1, GH2, GH3, are calculated. The increase due to the applied in the sequence, electrical insulation of the conductor or conductor bundle 6 is taken into account in determining the required dimensions.

According to the known state of the art, the conductors which are in the original state having a circular cross-section or the rope-like conductor bundle strands are formed or pressed onto a substantially rectangular cross-sectional shape with the dimensions calculated in advance. The outer insulation is then applied to these conductors or conductor bundles, which is usually formed by high-temperature-resistant insulating films and / or impregnated fabric tapes.

An advantageous manufacturing process for a choke coil described above is described in detail in AT 501 074 A1, which is based on the Applicant.

Air choke coils, i. Choke coils with air core or without iron core, are mainly used in electrical systems for energy transmission and power distribution, as well as in power supply systems of industrial plants. Due to the increasing density or intermeshing electrical power grids electrical medium and high voltage systems must be built more often in the immediate vicinity of residential areas, which entails an increasing demand for particularly low-noise inductors. This is increasingly reflected in the legal requirements regarding the permissible sound emission of electrical equipment. One property of the inductors known from the prior art is, inter alia, that they emit sound, depending on the type of power and current spectrum, especially when loaded with high alternating currents or combined load with high DC and AC, of people, especially in adjacent to the inductor installation Residential areas, is perceived as disturbing.

According to the state of the art, the problem of acoustic emissions is primarily counteracted by the fact that, in the design of the choke coil, care is taken that the frequencies of certain pronounced oscillation modes do not coincide with the frequency spectrum of the essential excitation forces. This will be unfavorable - A -

Noise increases due to mechanical resonance vibrations avoided. If the overall sound level is still too high, further measures are taken to reduce the noise emission of the choke coil. This can be, for example, a strategically favorable positioning of the choke coil within the high-voltage system. A conventional measure is also to encapsulate the choke coil as possible sound-absorbing, which may adversely affect the required air cooling. Thus, it is also known, as was indicated schematically in Fig. 3, the choke coils to assign a sound enclosure 8 or to arrange the choke coils in a separate building 9. An embodiment of soundproof walls 10 in addition to the choke coils represents a conventional measure.

These conventional methods may involve high additional costs and, moreover, technical problems with the electrical inlets and outlets 11, 12 to the

High voltage connections of the choke coil cause. For example, openings 13, 14 in a soundproof housing 8 for carrying out the electrical connections must have the required or at least necessary voltage spacings 15, 16, which can lead to a significant deterioration in the efficiency of the shielding effect of the sound.

Based on this prior art, the invention is based on the object

To create reactors with reduced or lowest possible acoustic emission, the measures to reduce or minimize the noise emissions should be as economical and effective.

This object is achieved by the measures according to claim 1. It is advantageous that a choke coil designed in this way has a significantly lower noise emission compared to conventional choke coils, in particular generates significantly less current flow-related noise in the form of a monotonous, acoustic hum signal. According to the invention, at least the outermost, current-carrying winding layer of the choke coil acts as a soundbar for the sound waves generated within the winding core. That is to say that the noises or vibrations arising in the inner winding layers of the choke coil are not emitted or only to a greatly reduced extent into the surroundings of the choke coil. The outermost shield winding itself has only a small or vemachläßigbar small natural vibration and therefore produces itself no or significantly lower or weaker sound emissions. An essential advantage of this embodiment is that the current-carrying, acoustic shield winding is at the same or approximately the same voltage potentials, as the at least one, immediately adjacent winding layer of the choke coil, whereby the risk of

Voltage flashovers is eliminated. Since the acoustic shield winding itself represents an electrical subcomponent, in particular a single coil of the choke coil, it is not necessary to comply with electrical minimum voltage spacings. Such minimum voltage gaps can be considerable distances in the high-voltage range, in particular up to one meter and even more. Especially with middle or

High-voltage systems, which prevail, for example, 60 kV, it is not necessary when using the inductance coil according to the invention, the sound-reducing or sound-blocking means, i. to the acoustic shield winding, to maintain a distance of about 60 cm. In particular, it is permissible or possible and expedient, the acoustic shield winding relatively close to the concentrically arranged winding layers of

Positioning inductor, since it is advantageously not necessary to take into account the applicable at the respective high voltage minimum voltage intervals. A choke coil according to the invention is therefore much quieter compared to conventional choke coils with the same or approximately the same electrical power. In addition, such a relatively quiet reactor installation is relatively compact in construction. In particular, the space required for an inventive, low-noise inductor is relatively low. Namely, even without external encapsulation, a choke coil according to the invention achieves relatively low sound level values, so that frequently without additional passive silencing measures, e.g. elaborate housing or cost-intensive building, the Auslangen can be found.

In the embodiment according to claim 2 or 3, an advantage is that the shield winding leads significantly lower current than the inner winding layers and thus hardly excited even to Schwinungungen. As a result, a relatively low-noise inductor can be achieved even without structurally relatively complex external enclosures or encapsulations.

The Reduzierungsaumaß for acoustic emissions can by the embodiment of claim 4 be further improved. In particular, this creates two radially distanced sound barriers for those sounds which are radiated from the inner or the innermost winding layers of the choke coil in the radial direction. In particular, the sound emitted radially in the direction of the coil center is thereby at least partially damped or intercepted by the inner acoustic shield winding.

Due to the embodiment according to claim 5, a vibration isolation or decoupling of the inner, vibrating during operation winding layers against the outer shield winding and against the outer shield windings is achieved. Also, the sound emission of such a choke coil is lowered considerably.

By the measures according to claim 6, it is avoided or at least partially achieved that the vibrating during operation vibrating or winding layers transmit their vibrational energy to the outer, formed as acoustic shield windings winding layers. As a result, the acoustic shield windings are hardly or significantly less excited to vibrate. As a result, a significantly lower noise emission of the choke coil results.

The avoidance of voltage differences or as uniform as possible a voltage gradient is achieved by the measures according to claim 7. It is advantageous that thereby no minimum voltage distances between the sound-shielding agent, i. the at least one acoustic shield winding, and the high voltage leading portion of the inductor must be adhered to. In particular, the acoustic shield winding is a subcomponent of the electrical functional components of the choke coil. Thus, it is possible to create noise-reduced choke coils which can also be constructed and operated in a relatively compact and cost-effective manner.

In the embodiment according to claim 8 it is advantageous that the current flowing in the acoustic shield winding current can be adjusted in an effective or trouble-free manner such that the acoustic shield winding is hardly excited to vibrate, so that the overall construction of the inductor has a relatively low acoustic emission having. The extent of sound attenuation or a limitation of sound propagation via the acoustic shield winding can be further improved by the embodiment according to claim 9. In particular, this significantly reduces the excitation of mechanical vibrations of the shield winding due to the mechanical vibrations of the inner winding layers of the choke coil.

An independent if necessary, inventive solution is specified in claim 10. It is advantageous that those sound waves, which arise within the winding and are redirected or redirected above all through the free spaces or gaps between the winding layers to the front ends of the choke coil, are not radiated or to a significantly reduced extent in the environment of the choke coil , Consequently, with such an extension section on at least one front end of the choke coil, a significantly reduced noise emission can be achieved. In particular, antiphase sound waves in the region of the zone formed by this extension section can at least partially extinguish. This measure for reducing the noise emissions is particularly effective and relatively inexpensive to implement.

The embodiment according to claim 11 avoids potential differences or achieves the most uniform possible axial voltage gradient in all winding layers. As a result, this measure for reducing noise emissions is reliable, relatively inexpensive and structurally particularly easy to produce.

By the measures according to claim 12, an undesirable propagation of the emerging at at least one front end of the choke coil sound waves is reduced or suppressed. The noise emissions of the inductor are thereby reduced to a significant extent.

By means of the measures according to claim 13, a possible uniform axial voltage gradient in all winding layers and thus the avoidance of significant voltage differences between the opposing turns of adjacent winding layers is achieved.

The reduction of the noise emissions can be further increased by the measures according to claim 14. In particular, thereby sound propagation in radial Direction of the coil center axis and in the radial direction away from the coil center axis minimized or suppressed.

By the provisions according to claim 15, a particularly effective combination, extinction and insulation of the sound radiation is achieved. The radial sound radiation of the inner winding layer or windings is largely in the vertical direction, i. deflected in the direction parallel to the coil center axis. Thus, the directional characteristic of the sound radiation is changed, whereby an at least partial extinction of the sound waves at the end or at the ends of the choke coil is supported. Since each vibrating winding layer emits largely the same sound power from its inside and outside, an efficient extinction can take place after the sound waves of these sound emissions are at least partially in opposite phase. In particular, a local merger of the propagating sound waves is achieved and opens the possibility of mutual extinction. In this mixing and extinction zone, especially the lower frequency components are extinguished.

The measures according to claim 16, the sound propagation of the higher frequency components can be better controlled. In addition, a higher degree of sound cancellation can be achieved in the mixing and extinguishing zone. A choke coil equipped in this way thus has a greatly reduced noise emission.

Due to the configuration according to claim 17, a good or sufficient cooling for the inner winding layers of the inductor is guaranteed in addition to an optimal or cost-effective and efficient suppression of sound propagation or sound emissions.

Regardless of the object of the invention is also achieved by a choke coil according to claim 18.

It is advantageous that those sound emissions, which emanate from the support or holding element for mechanical stabilization or electrical connection of the winding layers, are significantly reduced. In particular, a vibration excitation in a inventive holding or connecting element reduced, since a lateral buckling of the legs of the bow-shaped connecting element is eliminated or minimized. This buckling or vibration of the arms of a conventional holding element is mainly caused by the pump-like movements of the winding layers during the operation of the choke coil. The not inconsiderable sound source performing holding elements, which are also referred to in practice as winding stars are therefore replaced by the specified, comparatively less sound-emitting connection bracket or substituted by connecting bracket, which cause less sound power.

Due to the configuration according to claim 19 diametrically or rectilinear connections are avoided over the entire cross section of the choke coil. On the one hand, the angled connecting straps can fulfill the desired electrical connections between the winding layers and, moreover, contribute to the lowest possible or reduced acoustic emission, since the respective legs of the connecting straps do not buckle or scarcely buckle in their middle sections or vibrate relatively little.

An advantageous in static and, where appropriate, installation technical terms bow shape is specified in claim 20.

Due to the configuration according to claim 21, the requirements for a connection or electrical tap various fractions of a whole turn problemos be taken into account. At the same time, the required mechanical stability of the choke coil is achieved or the retention of the cylindrical shape or circular shape of the choke coil is ensured.

In the embodiment in claim 22 is advantageous that the buckling of the legs of the connecting bracket due to electromagnetic pumping or vibration movements of the choke coil is omitted or greatly reduced. In particular, a mechanical vibration of the connecting bracket or its leg is thereby reduced to a significant extent or even avoided.

Tensile stress or compressive stress-induced vibrations of the legs of the binding bracket, which may be different due to production and, for example, due to temperature changes during operation of the choke coil occur in various ways, have no or only marginal influence on the behavior of this connecting S Bügelwing by the embodiment according to claim 23. In particular, this creates particularly vibration or vibration-poor connection bracket.

Finally, the embodiment according to claim 24 is extremely vibration or low noise. In addition, operational thermal expansion of such a construction can be easily compensated. Temperature-influenced vibrations and noise sources or sound developments, which so far from the front-side holding or

Fasteners were caused, thereby largely avoided.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Each shows in a highly schematically simplified representation:

1 shows a detail of a choke coil of three coaxially arranged, cylindrical winding layers according to the prior art;

Fig. 2 is a detail detail of Figure 1 on an enlarged scale.

Fig. 3 conventional means for reducing during operation of a

Reactor coil resulting sound emissions;

Fig. 4 shows a choke coil in longitudinal section, with measures according to the invention

Reduction of their sound emissions;

5 shows the choke coil of Figure 4 in plan view ..;

6a to 6c front-side holding elements on choke coils according to the prior art;

7a to 7c inductor coils with end-side, according to the invention retaining elements in Ver various arrangement and Ausfürformungsformen.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component designations, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and these position information in a change in position mutatis mutandis to transfer to the new location. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent separate, inventive or inventive solutions.

All statements on ranges of values in the description of the subject should be understood to include any and all sub-ranges thereof, e.g. the indication 1 to 10 should be understood to include all sub-ranges, starting from the lower limit 1 and the upper limit 10, i. all subregions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

The basic structure of inductors and measures for reducing the noise emissions, as known from the prior art, have been previously described with reference to FIGS. 1 to 3.

Fig. 4 shows a schematic longitudinal section through a choke coil with several measures to reduce the noise emissions, which during active operation, i. occur at current flow through the inductor. The measures described below with reference to FIGS. 4 and 5 for reducing the noise emissions can be used combinatorially and also be used independently. The individual measures for sound reduction or suppression can each represent their own inventive solutions.

This inductor has a plurality of concentric with respect to their coil central axis 7 arranged and electrically connected in parallel winding layers 1. Such a choke coil is also referred to as a multi-layer choke coil, wherein in practice up to 20 winding layers 1 or individual coils can be formed. At least two such cylindrical winding layers 1 form a erfmdungsgemäße inductance coil, wherein the diameter of the concentric nested winding layers 1 is dimensioned such that between the lateral surfaces of the individual winding layers 1, ie between the individual coil windings, defined clearances or gaps 17 for Luftumspülung the winding layers , Are formed in particular as air flow channels. Usually, the winding layers 1 of the choke coil are distributed over the circumference of the winding layers or spaced from one another arranged insulation elements 5 - Fig. 2 -. Supports each other in the radial direction. These insulation elements 5 - Fig. 2 - are often referred to as gap strips.

The current distribution over the winding layers 1 connected in parallel has hitherto been chosen such that a substantially uniform temperature distribution over the individual winding layers 1 of the multi-layer inductance coil is achieved. The comparatively better cooling properties of the innermost and in particular the outermost winding layer 1 of the choke coil were taken into account accordingly. In conventional inductors, therefore, the outermost winding layer 1 and / or the innermost winding layer 1 has a higher current than the other winding layers 1, i. the adjacent or intermediate winding layers 1 or individual coils. The desired current distribution between the parallel connected winding layers 1 is - as known per se - essentially controlled by the number of turns of the individual winding layers 1.

In contrast, it is provided according to a measure according to the invention, at least the outermost winding layer 1 and possibly the innermost winding layer 1 as an acoustic shield winding 18 and 18 'form, which compared to the adjacent winding in the direction of the coil central axis 7 winding layer or compared to the nearest winding layer 1 has comparatively less power to transmit. At least the outermost winding layer 1 of the choke coil thereby forms a current-carrying, acoustic shield winding 18. In terms of its electrical properties, this shield winding 18 is dimensioned such that it is provided or designed to transmit a current that is only a fraction of the current that is to be transmitted from the immediately adjacent or closest winding layer 1. According to an advantageous further education is especially when at least three concentrically arranged, electrically connected in parallel winding layers 1 and individual coils are formed, even the innermost winding layer 1 of the inductor as quasi inner acoustic shield winding 18 'running. For this purpose, transmits this inner acoustic shield winding 18 'only a fraction of that current, which is to be transmitted from the adjacent, ie of the relatively larger in its diameter winding layer 1. According to an advantageous embodiment, the choke coil is thus embodied in such a way that the outermost winding layer 1 forms an outer acoustic shield winding 18 and innermost winding layer 1 of the multilayer or multiple choke coil forms an inner acoustic shield winding 18 '.

The screen windings 18, 18 'are thus formed by structurally largely unchanged electrical winding layers 1, which are also current-carrying, or which also serve for power transmission parallel to the inner or central winding layers 1 of the inductor. At least the outermost and possibly the innermost winding layer 1 of the choke coil thus forms an acoustic, acted upon by current and voltage shield winding 18, 18 'at the choke coil. The acoustic shield winding 18, 18 'is a sound barrier for sound emissions, which of the inner winding layers 1 and of the inner Teilbzw. Individual coils of the inductor are generated or emitted. In particular, that sound which is forcibly generated by the inner winding layers 1 of the choke coil is advantageously emitted or radiated into the surroundings of the choke coil only to a significantly reduced extent. In particular, an inner lateral surface 19 of the shield winding 18 and optionally an outer jacket surface 19 'of an inner shield winding 18' - referring to the coil central axis 7 - acts as a sound barrier, wherein the acoustic, current-carrying shield winding 18, 18 'itself, due to the relative low currents or power transmission, only causes a relatively low noise or represents a marginal and relatively uncritical sound source.

It is expedient here to dimension the acoustic screen winding 18 in such a way that it is provided or designed to transmit an amperage which is between 0.1% and at most 50% of the amperage which depends on the winding layer adjacent in the direction of the coil central axis 7 1 is to be transmitted. An advantageous dimensioning or current distribution within the choke coil is also given when the current to be transmitted by the acoustic shield winding 18 and / or 18 'is between 0.1% to 5% of that current, that of the choke coil as a whole, ie of all Winding layers 1, in particular of the shield winding 18, 18 'and of the other winding layers 1, is to be transmitted.

It is essential that the outer shield winding 18 and the possibly additionally formed, inner shield winding 18 'lead in comparison to the adjacent winding layers 1 relatively low currents and thus provide an effective effect as acoustic shield winding 18 and / or 18'. At the shield winding 18 and / or 18 'are the same or at least approximately the same voltage potentials, as at the immediately adjacent, electrically connected in parallel winding layer. 1

To achieve the desired current distribution ratios, it is desirable that the acoustic shield winding 18, 18 'have a higher electrical impedance Z, i. has a higher alternating current resistance, as the adjacent in the direction of the coil central axis 7 winding layer. 1

Another measure for minimizing or reducing acoustic emissions is to mechanically decouple the cylindrical lateral surface 19, 19 'of the acoustic screen winding 18, 18' with respect to the closest cylindrical lateral surface 20 of the adjacent winding layer 1 or the lateral surfaces 19, 19 'of FIG acoustic shield winding 18, 18 'with respect to the cylindrical surface 20 of the adjacent winding layer 1 to isolate vibration technology. For this purpose, especially in the Stirnendabschnitten between see the shield winding 18, 18 'and the adjacent winding layer 1 vibration or vibration damping compounds, for example, with the use of elastomeric elements, be formed. In particular, a continuous air gap or gap 17 with preferably uninterrupted, hollow cylindrical shape is formed between the inner or the outer jacket surface 19, 19 'of the acoustic screen windings 18, 18' and the closest lateral surface 20 of the adjacent winding layer 1. In particular, in the gap 17 between the shield winding 18, 18 'and the adjacent winding layer 1 no radially acting support elements, in particular no strip-shaped insulation elements 5 - as they are known from the prior art of FIG. 2 - arranged. This means that the manu- telflächen 19, 19 'relative to the lateral surfaces 20 in the radial direction of the inductor can not support each other. Thus, a transmission of mechanical vibrations or vibration via the lateral surfaces 19, 19 ', 20 is greatly minimized or reduced to the outside of the choke coil, whereby the noise emissions of such a choke coil can be lowered. The vibrations or vibrations occurring at the inner winding layers 1, which are caused by the winding layers 1 through which high alternating currents flow, are thereby hardly or significantly reduced to the outermost or innermost winding layer 1 of the choke coil.

An efficient measure for reducing noise emissions is also that a radial distance 21, 21 'between the lateral surface 19, 19' of the acoustic shield winding 18, 18 'and the lateral surface 20 of an adjacent winding layer 1 is dimensioned larger than a radial distance 22nd between two adjacent, concentric with the acoustic shield winding 18, 18 'arranged winding layers 1. Expedient conditions or effective effects are present when the distance 21, 21' is up to ten times larger, preferably sized about two to four times greater than the distance 22 between the inner winding layers 1. The distance 22 is usually in about 2 to 4 cm, preferably about 3 cm. That that the insulation elements 5 - according to FIG. 2 - between the inner winding layers 1 of the choke coil have a support width or bar width of usually about 3 cm.

The individual winding layers 1 and the at least one shield winding 18, 18 'are each designed as a hollow cylinder. The term lateral surface or cylindrical lateral surface 19, 19 ', 20 is to be understood as meaning the inner and / or outer lateral surfaces of these hollow or hollow cylindrical bodies.

Another, in particular independent measure for reducing the noise emissions is that at least one acoustic shield winding 18, 18 ', ie at least the outermost and possibly the innermost winding layer 1 of the inductor at least one front end extending in the axial direction, hollow cylindrical or polygonal Verlängerungsab - Section 23, 23 'has. This hollow-cylindrical extension section 23, 23 'which is hollow-cylindrical in cross-section or polygonal in cross-section adjoins at least one front end of the outermost and / or innermost winding layer 1. Ie that this extension section 23, 23 'is a structural extension of the current-carrying acoustic shield winding 18, 18' represents in the axial direction of the choke coil. In particular, the extension section 23, 23 'projects beyond the front ends of the winding layers 1 in the axial direction. The extension sections 23, 23 'thus represent, as it were, an extension of the electrical section of the choke coil. Preferably, the hollow cylindrical extension section 23, 23' is formed from electrically insulating material, for example from glass-fiber reinforced plastics or resin-impregnated tapes, which are wound into a hollow cylindrical shape , The preferably formed at least on the outermost shield winding 18 extension section 23 is thus preferably not energized. According to an advantageous embodiment, a hollow-cylindrical, electrically insulating and thus non-current-carrying extension section 23 'is also formed on the inner shield winding 18', in particular on the innermost winding layer 1. That is, the hollow-cylindrical extension section 23 and / or 23 'forms an electrically non-conductive end ring 24 and / or 24' on the choke coil, which at least one front end of the electrically conductive portion of the choke coil, in particular at least one front end of the shield winding 18, 18 ' connects. Preferably, at least at the upper end face of the shield winding 18, 18 ', in particular at the upper end of the outermost and / or innermost winding layer 1, an end ring 24, 24' executed.

An axial length or the winding layer height H of the current-carrying portion of the acoustic see-screen winding 18, 18 'corresponds at least approximately to an axial length or

Winding layer height H of the electrically parallel winding layers 1. According to a particularly effective embodiment, at least at the upper ends of the outer and inner acoustic shield winding 18, 18 'is an outer and inner hollow cylindrical or in plan view polygonal extension portion 23, 23' is formed. These respectively formed extension portions 23, 23 'extend the outer and the inner shield winding 18, 18' in the axial direction relative to the front ends of the winding layers 1 arranged therebetween.

Such an extension section 23, which is formed at least on the outer screen winding 18, results in an acoustic mixing and extinguishing zone 25 for

Sound waves, which emerge in the axial direction of the choke coil from the gap 17 and from the columns 17. In the region of the extension section 23 or 23 ', therefore, an acoustic near-field zone is formed in which the at the front ends of the winding layers 1 occur. sound is reduced or dampened. In particular, sound waves, which arise in the gaps 17, ie in the air gaps between the winding layers 1, deflected in the axial direction and guided to the front ends of the winding layers 1. In these front end regions, in which at least one extension section 23, 23 'is formed, the mixing and extinction zone 25 for the sound waves is formed. In particular, due to GE phased sound waves in the area of the mixing and extinguishing zone 25 at least some sound waves are canceled or compensated, whereby the noise emission of the choke coil is reduced. The compensation or extinguishing effect of the mixing and extinguishing zone 25 can be increased by forming both an outer extension section 23 and an inner extension section 23 ', since this produces a spatially delimited or defined mixing and extinguishing zone 25. However, such a mixing and extinguishing zone 25 also arises when an extension section 23 is formed only on the outer shield winding 18 or winding layer 1.

According to an advantageous development are following the mixing and / or

Extinguishing zone, in particular above and / or below the mixing and extinguishing zone 25, passive and / or reactive sound absorbing elements 26, for example blocks or plate elements made of foamed plastic or of fibers, such as e.g. Nonwovens or rock wool, formed. The sound absorbing elements 26 may also be provided by knit packages, fiber mats and / or relatively high mass acoustic absorber plates, such as, e.g. Tar plates, be formed. The sound absorbing elements 26 are preferably arranged distanced in the axial direction to the front ends of the winding layers 1. The mixing and extinguishing zone 25 for axially emerging, antiphase sound waves is formed in the space between the sound absorbing elements 26 and the front ends of the winding layers 1.

It is favorable to form a plurality of apertures in the sound absorbing elements 26 and / or, in the case of the formation of a plurality of sound absorbing elements 26, to arrange these spaced apart from one another, as can be seen by way of example in FIG. As a result, an air flow in the direction parallel to the coil center axis 7 is ensured between the winding layers 1. The individual sound absorbing elements 26 are distributed over the circumference of the choke coil and spaced from each other. In particular, these sound absorbing elements 26 allow escape of the air heated by the winding layers 1 within the gaps 17 from the interior of the throttle coil. Ie.

In the case of the described choke coil, it is advantageous that the outwardly directed sound radiation of the outer winding layer 1 is reduced in that it is embodied as a mechanically decoupled or vibration-insulated shield winding 18 and leads a relatively low current compared to the winding layer 1 adjacent in the direction of the coil center axis she herself is hardly excited to vibrate. Due to the current flow in the shield winding 18 or 18 ', there is a controlled voltage reduction, whereby this has approximately the same voltage potentials as the adjacent winding layer 1, which eliminates the risk of flashovers. Since the ends of the shield winding 18 or 18 'have the same electrical potential as the retaining elements 2 or the electrical connections of the choke coil, the electrical connection of the choke coil is unproblematic despite the acoustic shield winding 18 or 18'.

In FIGS. 6a to 6c, examples of four-armed holding elements 2 known from the prior art, as described with reference to FIGS. 1 and 2, are illustrated. These holding elements 2 may in practice also have only two or three or more than four star-shaped arms. In particular, holding elements 2 with up to twelve star-shaped arms are known from the prior art. These holding elements 2, which are often referred to as winding stars, have, inter alia, the task of

Choke coil to give sufficient mechanical stability and robustness. The holding elements 2 often also serve to distribute the total current to be conducted via the choke coil to the winding layers 1 connected in parallel. For this purpose, the holding element 2 is made of electrically conductive material, in particular of metal, such as e.g. Aluminum or stainless steel. The holding elements 2 are usually arranged at the top and at the bottom of the choke coil, as can be seen in Fig. 1. A retaining element 2 arranged on the upper side and on the lower side of the choke coil thus usually also forms the respective electrical connections for the supply and discharge of the coil current, as was schematically illustrated in FIGS. 6a to 6c by ring symbols.

According to the prior art, the holding elements 2 are thus star-shaped constructions, which are often formed from an aluminum profile. The individual arms of these star-shaped holding elements 2 can also be used to achieve the desired or required Power distribution between the winding layers serve. In particular, if one does not manage to fine-tune the current distribution in the winding layers 1 connected in parallel with an integer number of turns, fractions of an entire turn can also be tapped or provided via the arms of the holding element 2. That is, certain or selected arms of a holding element 2 are used to activate fractions of a turn in the individual, parallel winding layers. For example, according to the embodiment according to FIG. 6b, 25%, 50% or 75% of the last turn in the various winding layers 1 can be used. Of course, 100% of a turn can be used. In contrast, the electrical connection of the individual winding layers 1 in the embodiment according to FIG. 6a takes place in each case at a uniform position with respect to the circumference of the choke coil. The same applies to the embodiment of FIG. 6c. The electrical connection between the individual winding layers 1 and the holding element 2 has been illustrated by symbolic nodes.

In those sections of the holding element 2, in which no electrical connection with the winding layers 1 is provided, insulating elements 4 may be formed, which may also have a mutual support or stabilization function, as described with reference to FIGS. 1, 2. In particular, an electrically conductive holding arm 2 is preferably supported with the interposition of at least one electrical insulation element 4 with respect to the front ends of the winding layers 1, as is illustrated schematically above all in FIG. 2.

The arms of conventional holding elements 2 are connected to one another either directly or via a central hub 27, in particular welded or screwed together. Thus, in the known holding elements 2 or winding stars, a mechanically rigid connection exists between the arms or star arms.

The Applicant has recognized that these conventional holding elements 2 on the upper side of the coil and on the underside of the coil can represent a disturbing or problematic sound source. In particular, in dry-insulated air throttle coils, which can reach dimensions of up to several meters, these sound sources act independently and produce a disadvantageous, locally different noise spectrum. In particular, the Applicant recognized that the known constructions of holding elements 2 are exposed to an alternating tensile or compressive stress due to the pump-like movement of the alternating current flowing through the choke coil. Due in part to the rigid connection of the arms in the star center or center of the holding element 2, these arms alternately buckle laterally, as a result of which they swing correspondingly and can be a strong or disturbing source of noise. The extent of the noise generated by this effect is difficult to estimate and difficult to control, because this mechanical tension from the production process and thermal expansions during operation of the choke coil are an influence. In particular, the Applicant has recognized that the arms of the retaining elements 2 can represent a kind of membrane which generates unwanted sound.

If the holding element 2 is used in addition to the current distribution, then occur in the different arms different mechanical forces, which are caused on the one hand due to the different currents and on the other hand due to the different intense vibration excitation. The rigid connection of the individual arms in the center of the star-shaped holding element 2 causes a transfer of forces or vibrations to other arms, whereby they are also excited to vibrate and also generate noise.

Attempts had been made to reduce the mechanical vibrations of the arms of the holding elements 2 by supports or stiffeners 28 between the arms, as illustrated in FIG. 6a. However, this results in the problem that this causes arms, through which little or no current flows, and which would therefore generate little vibration of their own, to be excited to vibrate.

Based on this prior art, the Applicant has provided a relatively economical and effective solution for reducing or minimizing the noise emissions starting from the holding elements 2, as is illustrated by way of example with reference to FIGS. 7a to 7c. The embodiments according to FIGS. 7a to 7c can represent an independent inventive or erfmdungsgemäße solution. According to this embodiment, the holding element 2 is designed in several parts. In particular, at least two structurally independent holding elements are at the axial ends of the choke coil 2 executed so that they are not connected to each other in the center region of the choke coil, ie in the area around the coil center axis 7. That is, a rigid connection between the at least approximately radially or radially extending arms is avoided at the center point of the circular in plan view choke coil. This eliminates or reduces the swinging buckling of the arms due to the pump-like movement or vibration of the choke coil. In particular, the individual winding layers 1 of the choke coil can represent a type of pulsating tube with correspondingly high current flows, which transmits mechanical vibrations to the holding elements 2.

According to the invention, two legs 29, 30 each form a mechanical and / or electrical connection bracket 31 for at least one winding layer 1. It is essential that the two legs 29, 30 of such a connecting bracket 31 are angled away from one another, that is to say that an angle 32 is enclosed between the two legs 29, 30 of the connecting bracket 31. This angle 32 between the two legs 29, 30 of the electrical see and / or mechanical functions taking over connecting bracket 31 is less than 180 °, preferably 90 °. This angle 32 essentially depends on which stabilization effect is to be achieved by means of the connection bracket 31 and / or which partial angles or partial sections of an entire turn of the winding layers 1 are required. Especially when it is necessary to achieve relatively small partial turns, the angle 32 may also be less than 90 °.

An advantageous measure for reducing or minimizing the noise emissions of the choke coil is thus that at least one axial end face of the choke coil at least one angled extending connecting bracket 31 is formed, wherein the legs 29, 30 of this connecting bracket 31 in plan view of the choke coil to each other in a predetermined angle 32, which is less than 180 °. That is, the connection bracket 31 which satisfies a mechanical support function and / or an electrical conduction function does not extend diametrically or not continuously over the circular or hollow-cylindrical choke coil seen in plan view. Rather, the at least one electrical and / or mechanical connection bracket 31 is bent in such a way that a diametrical, rectilinear extent over the cross-sectional area of the choke coil is avoided. That is, the at least once, preferably repeatedly formed connecting bracket 31 in plan view of the front end of the choke coil, the geometric shape of a circle segment Defined or delimited.

Especially when the connection bracket 31 is intended to fulfill an electrical connection function between the winding layers 1 arranged concentrically in an electrically parallel manner, a plurality of connection straps 31 arranged distributed within the circumference of the choke coil are formed. Selected distal ends of the individual connecting straps 31 are provided for electrical connection to selected winding layers 1. In this case, it is expedient if the individual connection straps 31 are not mechanically connected to one another in the area around the coil central axis 7, in particular each independently of one another and do not form a central hub or a common hub 27. According to an advantageous embodiment, the individual connection straps 31 are mechanically and electrically connected to one another only in the distal end sections, in particular in the area of the winding layers 1.

Especially in the formation of a plurality of angled or bow-type connecting bracket 31, it is expedient if the adjacent legs 29, 30 of two adjacent connecting bracket 31 are spaced apart, so umnittelbar adjacent legs 29, 30 mechanically decoupled from each other, in particular vibration technology isolated from each other.

Between immediately adjacent legs 29, 30 of two adjacent connecting bracket 31 may also be provided a defined angle, as indicated in Fig. 7b with dashed lines. These angularly aligned legs 29, 30 are close to each other in the vicinity of the winding layers 1 to each other. Preferably, at the ends or near the front ends of the legs 29, 30 contact each other or go the legs 29, 30 in the region of the winding layers 1 into each other.

Instead of round transition sections between the two legs 29, 30 of a connecting bracket 31, it is also possible to provide oblique transitions between the two legs 29, 30, as was indicated by dashed lines in Fig. 7c by way of example.

Not required for power distribution connection bracket 31 can, if they also mechanically are not required, are omitted, as was illustrated in Fig. 7b, 7c.

Due to the described embodiment, the forces resulting from the flow of current and / or from the mechanical vibrations of the winding layers 1 in a connection bracket 31 are not transferred to the other connection clips 31 or only to a greatly reduced extent. This is primarily because the individual connecting straps 31 of the inventive retaining element 2 are mechanically and / or electrically interconnected only in the region of the winding layers 1 or the overall winding of the choke coil. Vibrations between the distal ends of the connecting bracket 31 and the winding layers 1 are prevented or almost non-existent due to the rigid connection of the distal ends of the connecting bracket 31 and the connecting bracket 31 with the winding layers 1.

The individual connection straps 31 are preferably electrically insulated from one another in the region between their distal ends, so that no circulating current can form due to electromagnetic induction. The connecting straps 31 are preferably clamped only at the winding or end-side end sections, i. connected to the winding layers 1. This can take place between the individual connection brackets 31 no power transmission, whereby this construction is relatively low vibration and low noise. In addition, thermal expansion of this construction of the holding element 2 consisting of at least one angled connecting bracket 31 can be easily compensated.

Thus, no significant or no critical forces can form or transmit between the individual connection straps 31. If necessary, stiffeners 28 may be formed, which extend only within a connecting bracket 31 and have no mechanical influence on other or adjacent connecting stirrups 31, as is best seen from the exemplary illustration according to FIG. 7c.

The embodiments show possible embodiments of a low-noise inductor, it being noted at this point that the invention is not restricted to the specifically illustrated embodiments of the same, but rather also various combinations of the individual embodiments are possible with each other and this variation possibility due to the teaching of technical action by objective invention in the skill of those skilled in this technical field. There are So also all conceivable variants of the execution, which are possible by combinations of individual details of the illustrated and described variant embodiment, includes the scope of protection.

For the sake of order, it should finally be pointed out that, for a better understanding of the design of the choke coil, these or their components have been shown partly out of scale and / or enlarged and / or reduced in size.

The object underlying the independent inventive solutions can be found in the description.

Above all, the individual embodiments shown in FIGS. 4, 5 and 7 can form the subject of independent solutions according to the invention. The relevant objects and solutions according to the invention can be found in the detailed descriptions of these figures.

REFERENCE NUMBERS

1 winding layer

2 retaining element

3 tension element

4 insulation element

5 insulation element

6 conductor bundles

7 coil center axis

8 soundproof housing

9 buildings

10 soundproof wall

11 supply line

12 derivative

13 opening

14 opening

15 voltage gap

16 voltage gap

17 gap

18.18 'screen winding

19, 19 'lateral surface

20 lateral surface

21.21 'distance 22 distance

23, 23 'extension section

24, 24 'end ring

25 mixing and extinguishing zone 26 Sound absorbing element

27 hub

28 stiffening

29 thighs

30 thighs

31 connection bracket

32 angles

H winding layer height GHl height of the conductor / conductor bundle

GH2 Height of the conductor / conductor bundle

GH3 Height of the conductor / conductor bundle

Claims

Patent claim

1. choke coil, in particular choke coil without iron core for use in electrical power supply networks, with at least two cylindrical, with respect to a coil lenmittelachse (7) concentrically arranged and electrically connected in parallel winding layers (1), and with at least one means for reducing or minimizing during the operation of the choke coil resulting sound emissions, characterized in that at least the outermost winding layer (1) as a current-carrying, acoustic shield winding (18) opposite to the coil center axis (7) adjacent winding layer (1) is formed, said shield winding (18) is electrically dimensioned such that it is designed to transmit a current that is only a fraction of that current, which is to be transmitted from the adjacent winding layer (1).

2. choke coil according to claim 1, characterized in that the acoustic shield winding (18) is dimensioned such that it is designed to transmit a current strength which is between 0.1% to a maximum of 50% of that current, which of Direction to the coil central axis (7) adjacent winding layer (1) is to be transmitted.

3. choke coil according to claim 1, characterized in that the of the acoustic shield winding (18) to be transmitted current is between 0.1% to 5% of that current, which is to be transmitted from the choke coil in total.

4. choke coil according to claim 1, characterized in that at least three concentrically arranged, electrically connected in parallel winding layers (1) are formed, wherein the outermost winding layer (1) forms an outer acoustic shield winding (18) and the innermost winding layer (1) an inner acoustic shield winding (18 ') forms.

5. choke coil according to claim 1 or 4, characterized in that a cylindrical outer surface (19, 19 ') of the acoustic shield winding (18, 18') with respect to a cylindrical peripheral surface (20) of the adjacent winding layer (1) mechanically decoupled or vibration isolated is.

6. choke coil according to claim 1 or 4, characterized in that between a lateral surface (19, 19 ') of the acoustic shield winding (18, 18') and a lateral surface (20) of the adjacent winding layer (1) has a continuous gap (17) is formed hollow cylindrical shape, so that in this gap (17) no radially acting support elements between the acoustic shield winding (18, 18 ') and the adjacent winding layer (1) are arranged.

7. choke coil according to claim 1 or 4, characterized in that the current-carrying, acoustic shield winding (18, 18 '), the same or at least approximately the same voltage potentials are present as at the immediately adjacent, electrically connected in parallel winding layer (1).

8. choke coil according to claim 1 or 4, characterized in that the acoustic shield winding (18, 18 ') has a higher electrical impedance than in the direction of the coil central axis (7) adjacent winding layer (1).

9. choke coil according to claim 1 or 4, characterized in that a radial distance (21) between a lateral surface (19, 19 ') of the acoustic shield winding (18, 18') and a lateral surface (20) of an adjacent winding layer (1) larger is dimensioned as a radial distance (22) between two immediately adjacent, concentric with the acoustic shield winding (18, 18 ') arranged winding layers (1).

10. choke coil according to claim 1, characterized in that the outermost winding layer (1), in particular the current-carrying, acoustic shield winding (18), at least one nem front end extending in the axial direction, a hollow cylindrical extension portion (23).

11. choke coil according to claim 10, characterized in that the hollow cylindrical extension portion (23) formed of electrically insulating material and is not current-leading.

12. choke coil according to claim 10, characterized in that the hollow cylindrical extension portion (23) forms an electrically non-conductive end ring (24), the at least one end of the electrically conductive portion of the shield winding (18) connects.

13. choke coil according to claim 10, characterized in that an axial length or winding layer height (H) of the current-carrying portion of the acoustic shield winding

(18) at least approximately corresponds to an axial length or winding layer height (H) of the winding layers (1).

14. choke coil according to claim 4, characterized in that at least at the upper ends of the outer and the inner acoustic shield winding (18, 18 ') respectively an outer and inner hollow cylindrical extension portion (23, 23') is formed, which the outer and inner acoustic shield winding (18, 18 ') in the axial direction opposite the front ends of the interposed winding layers (1) extended.

15. choke coil according to claim 10 or 14, characterized in that in addition to the hollow cylindrical extension portion (23), in particular between the outer and inner hollow cylindrical extension portion (23, 23 ') an acoustic mixing and extinguishing zone (25) for sound waves, which occur this axial end face of the winding layers (1) is formed.

16. A choke coil according to claim 15, characterized in that in the axial direction of the coil central axis (7) after the mixing and extinguishing zone (25) passive and / or reactive Schallabsorbierungselemente (26), for example blocks or plate elements made of plastic foam or fibers such. Nonwovens or rock wool, are formed.

17. choke coil according to claim 16, characterized in that in the Schallabsorbie- ing elements (26) openings are formed or that several Schallabsorbierungselemente (26) are arranged spaced apart, so that between the winding layers (1) an air flow in a direction parallel to the coil center axis (7 ) is guaranteed.

18. choke coil, in particular choke coil without iron core for use in electrical energy supply networks, with at least two cylindrical, with respect to a coil central axis (7) concentrically arranged and electrically connected in parallel winding Layers (1), with at least one holding element (2) for the mechanical stabilization and optionally electrical connection of the winding layers (1), and with at least one means for reducing or minimizing noise emissions during operation of the choke coil, characterized in that the holding element ( 2) is formed by an angle bracket (31) arranged at at least one axial front end of the choke coil, and in that this connection bracket (31) is formed by two limbs (29, 29) oriented at an angle to each other, at least approximately radially to the coil center axis (7). 30) is formed.

19. choke coil according to claim 18, characterized in that the connecting bracket

(31) is electrically conductive and is provided for electrical parallel connection of winding layers (1), wherein between the two legs (29, 30) of the connecting bracket (31) included angle (32) is less than 180 °, preferably 90 °.

20. choke coil according to claim 18, characterized in that the connecting bracket (31) defines the geometric shape of a circular segment in plan view of the front end of the choke coil.

21. A choke coil according to claim 18, characterized in that a plurality of distributed within the circumference of the choke coil arranged connecting bracket (31) are formed and that selected, distal ends of the individual connecting bracket (31) for electrical connection with selected winding layers (1) are provided.

22. choke coil according to claim 18, characterized in that a plurality of connecting bracket (31) are formed and the individual connecting bracket (31) in the vicinity of the

Coil center axis (7) or in the region of the center of the circular in plan view winding layers (1) each independently of one another and are not mechanically connected to each other, in particular no central hub (27) form.

23. choke coil according to claim 18, characterized in that a plurality of connecting straps (31) are formed and the individual connecting bracket (31) only in the distal end portions, in particular in the region of the winding layers (1) are mechanically and electrically interconnected.

24. choke coil according to claim 18, characterized in that a plurality of connecting bracket (31) are formed and the nearest leg (29, 30) of two adjacent connecting bracket (31) extend at least approximately parallel and spaced from each other, so that immediately adjacent leg (29 , 30) are mechanically decoupled from each other.