Patent Description:
Competitive market and environmental concerns have placed a drastic demand on reactor manufacturers to design less noisy coils. However, designing a silent coil has its own limitations. Therefore, the only possible solution is to control propagation of the sound generated in a reactor.

<CIT> describes an air core power reactor having a noise mitigating sound shield.

The following methods have been used so far to attenuate noise generated within an air-core reactor:.

The low force package is an external winding package which carries lower current and it is semi-decoupled from the rest of packages.

These kinds of sound shields are manufactured as an outermost fiberglass packages or cylinders. The zero force packages don't have acoustic lining or current. They are manufactured by hand-lay up or wet roving technology in a uniform or a modular format.

They are an external fiberglass package lined with acoustic absorption materials (e.g. mineral wool, fiberglass, etc.). The method is based on the sound absorption of the sound generated within an air-core reactor. Three types of the integrated sound shields have been developed at Trench limited so far: the first model is secured to the outermost surface of a reactor by means of friction. In the second type, the friction was eliminated. It is worth mentioning that the attenuation mechanism in both designs is based on sound absorption of the absorbent materials. In addition, there are other sound shields based on single wall isolation and the absorption concept that are used. However, still better solutions based on enhancement in sound transmission loss (STL) are needed to attenuate noise generated within an air-core reactor.

Therefore, there is a need of a better sound shield system to attenuate noise generated within an air-core reactor.

Briefly described, aspects of the present invention relate to a sound shield system based on enhancement in sound transmission loss (STL) using a concentric double-cylinders and sound attenuation panels decoupled from cylinders by air gaps. The proposed solution is based on increasing the sound transmission loss (STL) in the sound shield system. Therefore, less acoustic power is transmitted to a receiving side by using double concentric cylinders (double walls) and the resonances of an acoustic cavity between two double walls are attenuated using modular sound absorbent panels.

In accordance with one illustrative embodiment of the present invention, an air core dry type power reactor according to claim <NUM> is provided. The reactor comprises upper and lower spider units each comprising a plurality of support arms extending radially outward from a central axis. The reactor further comprises a coil including a plurality of cylindrically shaped winding layers concentrically positioned about one another and with respect to the central axis, the plurality of cylindrically shaped winding layers including an outermost layer. The reactor further comprises a double wall sound shield including concentric a first roving cylinder and a second roving cylinder, the first roving cylinder positioned against the outermost layer but detached from the coil by a first airgap between the outermost layer and the first roving cylinder to reduce a structure-borne transmission of an acoustic energy or attached by ductsticks to the coil. The second roving cylinder is placed at a distance from the first roving cylinder to form an acoustic cavity between two double walls of the first roving cylinder and the second roving cylinder. The double wall sound shield further includes a plurality of sound absorbent panels to attenuate resonances of the acoustic cavity between the two double walls of the first roving cylinder and the second roving cylinder. The plurality of sound absorbent panels comprises a layer of sound absorbing material and each of the plurality of sound absorbent panels is separated from the first roving cylinder by a second airgap.

In accordance with another illustrative embodiment of the present invention, a method of attenuating noise generated within an air-core reactor according to claim <NUM> is provided. The method comprises providing upper and lower spider units each comprising a plurality of support arms extending radially outward from a central axis. The method further includes providing a coil including a plurality of cylindrically shaped winding layers concentrically positioned about one another and with respect to the central axis, the plurality of cylindrically shaped winding layers including an outermost layer. The method further includes providing a double wall sound shield including concentric a first roving cylinder and a second roving cylinder, the first roving cylinder positioned against the outermost layer but detached from the coil by a first airgap between the outermost layer and the first roving cylinder to reduce a structure-borne transmission of an acoustic energy or attached by ductsticks to the coil. The second roving cylinder is placed at a distance from the first roving cylinder to form an acoustic cavity between two double walls of the first roving cylinder and the second roving cylinder. The double wall sound shield further includes a plurality of sound absorbent panels to attenuate resonances of the acoustic cavity between the two double walls of the first roving cylinder and the second roving cylinder. The plurality of sound absorbent panels comprises a layer of sound absorbing material and each of the plurality of sound absorbent panels is separated from the first roving cylinder by a second airgap.

To facilitate an understanding of embodiments, principles, and features of the present invention, they are explained hereinafter with reference to implementation in illustrative embodiments. In particular, they are described in the context of a double wall system that is detached from a coil by an airgap between an outermost winding package and a first roving cylinder. This reduces the structure-borne transmission of the acoustic energy. Then, a second roving cylinder is placed at a definite distance from the first roving cylinder. Next, the resonances of an acoustic cavity between two double walls are attenuated using a plurality of modular sound absorbent panels. The modular sound absorbent panels are sandwiched between mesh-grid fiberglass sheets to increase the sound absorption in the acoustic cavity and also increase the bending resistivity of the panels. However, the sound panels are separated from the first roving cylinder by an airgap that results in better sound absorption and improves curing process of the fiberglass cylinder. To increase the absorption surface and reduce impedance miss- match between air and an absorbent layer, the surface of the absorbent materials has been made in a step-shape. The absorbent panels fill up to a definite percentage of the space between concentric cylinders which is defined based on the frequency range of a reactor and volume. Therefore, considerable material savings and weight reduction compared to previous models is achieved. The dimensions of sound panels are fixed for coils with various dimensions. Therefore, standardizing the size and changing the configuration results into considerable reduction in manufacturing cost. In addition, installation of sound panels is easier than common sound panels that results in labor hours saving during sound shield installation. The number of sound panel rows along an axis is defined based on a distance between upper and lower spiders (DBS) of the coil. Embodiments of the present invention, however, are not limited to use in the described devices or methods.

The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present invention.

These and other embodiments of the double wall sound shield with modular sound absorbent panels for an air core reactor according to the present disclosure are described below with reference to <FIG> herein. Like reference numerals used in the drawings identify similar or identical elements throughout the several views. The drawings are not necessarily drawn to scale.

Consistent with one embodiment of the present invention, <FIG> represents a representation of a diagrammatic view of an air core dry type power reactor <NUM> including a double wall sound shield <NUM> with a plurality of modular sound absorbent panels <NUM>(<NUM>-n) sandwiched between double walls of first and second roving cylinders <NUM>(<NUM>, <NUM>) in accordance with an exemplary embodiment of the present invention. A system is based on increasing transmission loss by using double concentric cylinders <NUM> and attenuating of the resonance of an acoustic cavity located between the two cylinders <NUM>. Therefore, less acoustic power will be transmitted to the receiving side by using double concentric cylinders <NUM> (a double wall concept) and the resonances of the acoustic cavity between two double walls are attenuated using the sound absorbent panels <NUM>.

The air core dry type power reactor <NUM> further comprises upper and lower spider units <NUM>(<NUM>, <NUM>) each comprising a plurality of support arms <NUM> extending radially outward from a central axis <NUM>. The air core dry type power reactor <NUM> further comprises a coil <NUM> including a plurality of cylindrically shaped winding layers <NUM>(<NUM>-m) concentrically positioned about one another and with respect to the central axis <NUM>. The plurality of cylindrically shaped winding layers <NUM>(<NUM>-m) including an outermost layer <NUM>. The first roving cylinder <NUM>(<NUM>) can be either attached to the coil <NUM> by ductsticks or completely detached from the coil <NUM>.

The double wall sound shield <NUM> includes concentric the first roving cylinder <NUM>(<NUM>) and the second roving cylinder <NUM>(<NUM>). The first roving cylinder <NUM>(<NUM>) is positioned against the outermost layer <NUM> but detached from the coil <NUM> by a first airgap <NUM>(<NUM>) between the outermost layer <NUM> and the first roving cylinder <NUM>(<NUM>) to reduce a structure-borne transmission of an acoustic energy. The second roving cylinder <NUM>(<NUM>) is placed at a distance from the first roving cylinder <NUM>(<NUM>) to form an acoustic cavity <NUM> between two double walls of the first roving cylinder <NUM>(<NUM>) and the second roving cylinder <NUM>(<NUM>). The double wall sound shield <NUM> further including the plurality of modular sound absorbent panels <NUM>(<NUM>-n) to attenuate resonances of the acoustic cavity <NUM> between the two double walls of the first roving cylinder <NUM>(<NUM>) and the second roving cylinder <NUM>(<NUM>). The plurality of modular sound absorbent panels <NUM>(<NUM>-n) comprises a layer of sound absorbing material and each of the plurality of sound absorbent panels <NUM> is separated from the first roving cylinder <NUM>(<NUM>) by a second airgap <NUM>(<NUM>) (see in the side view and a front view of the sound panel <NUM> as shown in <FIG>).

The double wall sound shield <NUM> is configured to increase a transmission loss such that less acoustic power will be transmitted to a receiving side by using double concentric walls of the first roving cylinder <NUM>(<NUM>) and the second roving cylinder <NUM>(<NUM>). The double wall sound shield <NUM> is configured to control propagation of sound generated in the reactor <NUM> to attenuate noise generated within the reactor <NUM> with a combination of a sound shield structure <NUM> that enhances sound transmission loss (STL) using a concentric double cylinder structure <NUM> and a sound attenuation panel structure <NUM> decoupled from the concentric double cylinder structure <NUM> by air gaps <NUM>. The double wall sound shield <NUM> including double absorbent surface and the plurality of sound absorbent panels <NUM> being modular sound panels.

Referring to <FIG>, it illustrates a cutout view of the plurality of modular sound absorbent panels <NUM>(<NUM>-n) that are placed between a double wall system <NUM> to dissipate the double wall resonance in accordance with an exemplary embodiment of the present invention. The present invention introduces the double wall system <NUM> based on enhancement in sound transmission loss (STL) using concentric double-cylinders <NUM> and the sound attenuation panels <NUM> decoupled from the cylinders <NUM> by an air-gap concept to control propagation of the sound generated in the reactor <NUM>.

The plurality of sound absorbent panels <NUM> are modular and standardized such that dimensions of the plurality of sound absorbent panels <NUM> are sized regardless of dimensions of the coil <NUM>. In other words, the plurality of sound absorbent panels <NUM> have a standard size for all type of reactors. This property results in manufacturing cost reduction. The double wall system <NUM> achieves considerable material savings. Reduction of weight lets one to eliminate the vertical sticks in previous designs. Changing the functionality of sound panels from sound absorption panels <NUM> to the double wall sound barriers results in elimination of structural epoxy resin fiberglass mesh and fiberglass ties. Reducing the weight of sound shield results saving in other supporting structures. Mass reduction and uniform size for panels result in reduction in production cost of the plurality of sound absorbent panels <NUM>.

Turning now to <FIG>, it illustrates a side view of a modular sound absorbent panel <NUM> used to increase sound absorption in accordance with an exemplary embodiment of the present invention. The modular sound absorbent panel <NUM> includes a width dimension <NUM> extending along a radial direction with respect to the central axis <NUM> (see <FIG>) to provide a separation distance <NUM> between the first roving cylinder <NUM>(<NUM>) and the modular sound absorbent panel <NUM> such that the separation distance <NUM> defines a acoustic cavity <NUM>. The modular sound absorbent panel <NUM> has two opposing major surfaces <NUM>(<NUM>, <NUM>) that form an absorbent layer of absorbent materials such that each of the two opposing major surfaces has a step-shape surface <NUM> to increase an absorption surface and reduce impedance mismatch between air and the absorbent layer. The modular sound absorbent panel <NUM> is sandwiched between two mesh-grid fiberglass sheets <NUM>(<NUM>, <NUM>) to increase the sound absorption in the acoustic cavity <NUM> and also increase the bending resistivity of the panel <NUM>.

The modular sound absorbent panel <NUM> comprises installation means <NUM> such that an installation labor hour saving associated with installation of the modular sound absorbent panel <NUM> during the double wall sound shield installation is better than installing of common known sound panels. The plurality of sound absorbent panels <NUM> comprises production and the installation means <NUM> such that standard sound panels eliminates custom designing that results in lower production cost. In addition, installation of these panels <NUM>, because of their size and weight, can be performed by one operator and is faster than common known sound panels.

The plurality of sound absorbent panels <NUM>(<NUM>-n) fill up a percentage of the space between concentric the first roving cylinder <NUM>(<NUM>) and the second roving cylinder <NUM>(<NUM>) such that the percentage of the space filled is defined based on a frequency range and a volume of the air core dry type power reactor <NUM>. <MAT>
where.

<FIG> illustrates a top view of the modular sound absorbent panel <NUM> of <FIG> in accordance with an exemplary embodiment of the present invention. As seen in <FIG>, it illustrates a cross-sectional view of the modular sound absorbent panel <NUM> of <FIG> at a line A-A' in accordance with an exemplary embodiment of the present invention. The modular sound absorbent panel <NUM> comprises a layer of sound absorbing material <NUM>. The modular sound absorbent panel <NUM> may be an external fiberglass package lined with acoustic absorption materials (e.g. mineral wool, fiberglass etc.). The attenuation mechanism is based on sound absorption of the absorbent materials using innovative sound absorbent panels.

As shown in <FIG>, it illustrates a bottom view of the modular sound absorbent panel <NUM> of <FIG> in accordance with an exemplary embodiment of the present invention. In <FIG>, it illustrates a front view of the modular sound absorbent panel <NUM> of <FIG> with a front mesh <NUM> in accordance with an exemplary embodiment of the present invention. For example, the modular sound absorbent panel <NUM> is sandwiched between two mesh-grid fiberglass sheets to increase the sound absorption in the acoustic cavity <NUM> and also increase the bending resistivity of the panel <NUM>. A mesh on outer and inner surfaces of the panel <NUM> is used to increase sound dissipation.

With regard to <FIG>, it illustrates a pressure drop when excitation is completely isolated from the receiving side in accordance with an exemplary embodiment of the present invention. An impact of using the double wall system <NUM> instead of a single wall on sound transmission loss is shown in <FIG>. A single wall curve <NUM>, a double wall curve <NUM>, a double wall plus foam curve <NUM> (with sound panels <NUM>) are shown.

With respect to <FIG>, it illustrates a cutout view of an air core dry type power reactor <NUM> including a double row <NUM>(<NUM>, <NUM>) of modular sound absorbent panels <NUM> in accordance with an exemplary embodiment of the present invention. A given number of sound panel rows along an axis being defined based on a distance (D) <NUM> between the upper and lower spider units <NUM>(<NUM>, <NUM>) (DBS) of the coil <NUM>. <MAT>
where.

<FIG> illustrates a cutout view of a plurality of modular sound absorbent panels <NUM>(<NUM>-n) in which a length <NUM> of the sound panels is extended from upper to lower spider units <NUM>(<NUM>, <NUM>) in accordance with an exemplary embodiment of the present invention. The length <NUM> of the sound panels <NUM> can be extended from top to bottom spider units <NUM>(<NUM>, <NUM>) for special cases such as high voltage cases.

<FIG> illustrates a schematic view of a flow chart of a method <NUM> of attenuating noise generated within the air-core reactor <NUM>, <NUM> in accordance with an exemplary embodiment of the present invention. Reference is made to the elements and features described in <FIG>. It should be appreciated that some steps are not required to be performed in any particular order, and that some steps are optional.

The method <NUM> includes a step <NUM> of providing upper and lower spider units each comprising a plurality of support arms extending radially outward from a central axis. The method <NUM> further includes a step <NUM> of providing a coil including a plurality of cylindrically shaped winding layers concentrically positioned about one another and with respect to the central axis, the plurality of cylindrically shaped winding layers including an outermost layer. The method <NUM> further includes a step <NUM> of providing a double wall sound shield including concentric a first roving cylinder and a second roving cylinder, the first roving cylinder positioned against the outermost layer but detached from the coil by a first airgap between the outermost layer and the first roving cylinder to reduce a structure-borne transmission of an acoustic energy.

While a rectangular sound panel is described here a range of one or more other shapes of sound panels or other forms of sound panels are also contemplated by the present invention. For example, other types of sound panels or other sound panels of a full length along height or a full width along diameter or a fully coil-covering cylinder shape sound panel may be implemented based on one or more features presented above.

The techniques described herein can be particularly useful for modular sound absorbent panels that are sandwiched between two opposing mesh-grid fiberglass sheets. While particular embodiments are described in terms of the two-sheet structure, the techniques described herein are not limited to the two-sheet structure but can also be used with a multi-sheet structure.

Embodiments and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known starting materials, processing techniques, components and equipment are omitted so as not to unnecessarily obscure embodiments in detail. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments, are given by way of illustration only and not by way of limitation.

For example, a process, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, article, or apparatus.

Claim 1:
An air core dry type power reactor (<NUM>) comprising:
upper and lower spider units (<NUM>(<NUM>), <NUM>(<NUM>)) each comprising a plurality of support arms (<NUM>) extending radially outward from a central axis (<NUM>);
a coil (<NUM>) including a plurality of cylindrically shaped winding layers (<NUM>(<NUM>-m)) concentrically positioned about one another and with respect to the central axis (<NUM>), the plurality of cylindrically shaped winding layers (<NUM>(<NUM>-m)) including an outermost layer (<NUM>); and
a double wall sound shield (<NUM>) including two concentric roving cylinders, a first roving cylinder (<NUM>(<NUM>)) and a second roving cylinder (<NUM>(<NUM>)), the first roving cylinder (<NUM>(<NUM>)) positioned against the outermost layer (<NUM>) but detached from the coil (<NUM>) by a first airgap (<NUM>(<NUM>)) between the outermost layer (<NUM>) and the first roving cylinder (<NUM>(<NUM>)) to reduce a structure-borne transmission of an acoustic energy or attached by ductsticks to the coil (<NUM>),
wherein the second roving cylinder (<NUM>(<NUM>)) is placed at a distance from the first roving cylinder (<NUM>(<NUM>)) to form an acoustic cavity (<NUM>) between two double walls of the first roving cylinder (<NUM>(<NUM>)) and the second roving cylinder (<NUM>(<NUM>)),
wherein the double wall sound shield (<NUM>) further includes a plurality of sound absorbent panels (<NUM>(<NUM>-n)) to attenuate resonances of the acoustic cavity (<NUM>) between the two double walls of the first roving cylinder (<NUM>(<NUM>)) and the second roving cylinder (<NUM>(<NUM>)),
wherein each of the plurality of sound absorbent panels (<NUM>(<NUM>-n)) comprises a layer of sound absorbing material (<NUM>) and each of the plurality of sound absorbent panels (<NUM>(<NUM>-n)) is separated from the first roving cylinder (<NUM>(<NUM>)) by a second airgap (<NUM>(<NUM>)), and
characterized in that each of the plurality of sound absorbent panels (<NUM>(<NUM>-n)) comprises installation means (<NUM>) and wherein each of the plurality of sound absorbent panels is attached to the first roving cylinder (<NUM>(<NUM>)) by its installation means (<NUM>).