Fan differential pressure cooling structure for dynamoelectric machine

Abstract

A fan differential pressure cooling structure for a dynamoelectric machine (36) is disclosed. The cooling structure includes a fan (66) disposed on the outer surface of a rotatable shaft (14) on which a rotor body (12) having a field windings of coils (18) is mounted thereon. Movement of the fan creates a differential pressure that causes a flow of the coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into the coolant inlet (64) and through various passages formed in the rotatable shaft to cool conducting elements (60) disposed therein and out through a coolant outlet (80) arranged on the outer surface of the rotatable shaft about the fan proximate a casing (38) within which the rotor and a portion of the shaft are disposed.

Description

FAN DIFFERENTIAL PRESSURE COOLING STRUCTURE FORDYNAMOELECTRIC MACHINEBACKGROUNDTECHNICAL FIELD

[0001] Embodiments of this disclosure relate generally to dynamoelectric machines, and more specifically, to a fan differential pressure cooling structure for cooling conducting elements in a dynamoelectric machine.DISCUSSION OF ART

[0002] A dynamoelectric machine, such as for example, an electrical generator, includes a rotor body that can be made of a ferrous metal material that is rotatably mounted on a shaft via a bearing assembly. Arranged circumferentially about the mid-section of the rotor body are a multiple of axially oriented slots extending radially outward from a center of the rotor body that hold a multiple of field windings of coils that are typically made of copper. These field windings of coils can include longitudinally oriented central windings secured within the slots, and turns of endwindings extending out from the slots at axial ends of the rotor body.The shaft of the electrical generator can include a driven end having a coupling for a prime mover, such as for example a gas turbine or a steam turbine, that is operative to turn the shaft. The turning of the shaft by the prime mover produces a rotating magnetic field within the machine. This induces a three-phase set of voltages with stator windings in a stator of theelectrical generator that encloses the rotor body. The opposing end of the shaft, which can be referred to as the non-driven end, can be coupled to an excitation current source that can supply an electrical current to the shaft as the shaft rotates. The electrical current passes internally through the shaft to the field windings of coils in the rotor body. In this manner, the electrical current that passes from the excitation current source to the field windings of coils can maintain the rotating electromagnetic field at a fixed polarity.

[0003] As current flows in conductors or conducting elements disposed in the shaft to the field windings of coils, heat is generated. Typically, there are a lot of conducting elements and a lot of current flowing through the conducting elements disposed in the shaft between the field windings of coils, generating a lot of heat. If that heat is not “removed," then the windings of coils can be damaged.

[0004] One approach to “removing the heat” involves circulating a coolant fluid, such as hydrogen, through the electrical generator and around the rotor body to cool various components including the field windings of coils and the conducting elements disposed in the shaft. In general, hydrogen is much better at absorbing heat than other cooling mediums such as air. This means that for a generator of the same size, if it's cooled with hydrogen versus air, then more current can flow in the stator and rotor windings of coils, which means that the generator can produce more power. The benefits of using hydrogen as a coolant fluid instead of air, enable power plant operators to deploy smaller electricalgenerators that not only reduce the physical size footprint of the generator within the plant, but also the cost of the generator.

[0005] Nevertheless, there is a continuing trend in the power generation industry towards the use of electrical generators with increased capacity. Since the physical dimensions of the electrical generators cannot in many cases be conveniently increased to satisfy this rise in capacity demands, it has been necessary to expand the current loading on the conducting elements. This gives rise to an added burden of heat removal from the conducting elements inside the generator casings.Consequently, there is a need for improved cooling structures that have the capability to absorb the higher heat in the conducting elements that arises as plant operators trend towards increasing capacity of the electrical generators.BRIEF DESCRIPTION

[0006] The following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the various embodiments described herein. This summary is not an extensive overview of the various embodiments. It is not intended to exclusively identify key features or essential features of the claimed subject matter set forth in the Claims, nor is it intended as an aid in determining the scope of the claimed subject matter. Its sole purpose is to present some concepts of the disclosure in a streamlined form as a prelude to the more detailed description that is presented later.

[0007] The various embodiments are directed to an improved cooling structure for a dynamoelectric machine that is based on fan differential pressure. The cooling structure of the various embodiments includes an axial fan disposed on the outer surface of a rotatable shaft on which a rotor body having field windings of coils is mounted thereon.Movement of the fan creates a differential pressure that causes a flow of a coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into a coolant inlet and through various passages formed in the rotatable shaft to cool conducting elements disposed therein and out through a coolant outlet arranged on the outer surface of the rotatable shaft about the fan proximate a casing within which the rotor and a portion of the shaft are disposed.

[0008] The cooling structure of the various embodiments allows a dynamoelectric machine, such as for example an electrical generator, to be designed with conducting elements having high current density. This capability permits the electrical generator to use fewer conducting elements that are made of copper. This is in contrast to conventional conduction cooling solutions that utilize far more copper conducting elements that are only able to manage considerably lower current densities, which is not ideal as power plant operators trend toward increasing capacity of electrical generators to operate at higher current densities.

[0009] In accordance with a first embodiment, a dynamoelectric machine is provided. The dynamoelectric machine of this embodiment comprises: a casing; a rotor body within the casing, the rotor body havinga plurality of field windings of coils secured thereabout; a rotatable shaft on which the rotor body mounts thereon with an end extending out from the casing, the shaft having an axial bore extending between an inner extremity of the bore that advances into the rotor body and an outer extremity of the bore that extends out from the rotor body and through the casing, a plurality of radial passages communicating with the axial bore, with at least one radial passage near an end of the inner extremity of the bore extending to a first region of an outer surface of the rotatable shaft and a radial passage extending from the inner extremity of the bore to a second region of the outer surface of the rotatable shaft proximate the casing, conducting elements disposed longitudinally in the axial bore from the outer extremity to the inner extremity of the bore and conducting elements disposed radially in the at least one radial passage, a main lead extending axially from the conducting elements in the at least one radial passage near the first region of the outer surface of the rotatable shaft to connect with the plurality of field windings of coils, and a coolant inlet formed about the first region of the outer surface of the rotatable shaft proximate the at least one radial passage, the main lead and the plurality of field windings of coils to receive a coolant fluid circulating in the casing about the rotor body and the rotatable shaft; and a fan disposed on the second region of the outer surface of the rotatable shaft within the casing above the radial passage extending from the inner extremity of the bore proximate the casing, the fan having a high pressure side facing the rotor body and the plurality of field windings of coils and a lower pressure suction side facing the casing, wherein movement of the fan creates adifferential pressure that causes a flow of the coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into the coolant inlet and through the at least one radial passage near the end of the inner extremity of the bore and the axial bore to cool the conducting elements disposed therein, and into the radial passage extending from the inner extremity of the bore proximate the casing and through a discharge port formed therein to a coolant outlet arranged on the outer surface of the rotatable shaft about the suction side of the fan.

[0010] In accordance with a second embodiment, a dynamoelectric machine is provided. The dynamoelectric machine of this embodiment comprises: a casing; a rotor body enclosed within the casing, the rotor body having a plurality of field windings of coils secured thereabout; a rotatable shaft on which the rotor body mounts thereon with an end extending out from the casing, the shaft having an axial bore extending between an inner extremity of the bore that advances into the rotor body and an outer extremity of the bore that extends out from the rotor body and through the casing, a plurality of radial passages communicating with the axial bore, with at least one radial passage near an end of the inner extremity of the bore extending to a first region of an outer surface of the rotatable shaft and a radial passage extending from the inner extremity of the bore to a second region of the outer surface of the rotatable shaft proximate the casing, conducting elements disposed longitudinally in the axial bore from the outer extremity to the inner extremity of the bore and conducting elements disposed radially in the at least one radial passage, a main lead extending axially from the conducting elements in the at leastone radial passage near the first region of the outer surface of the rotatable shaft to connect with the plurality of field windings of coils, and a coolant inlet formed about the first region of the outer surface of the rotatable shaft proximate the at least one radial passage, the main lead and the plurality of field windings of coils to receive a coolant fluid circulating in the casing about the rotor body and the rotatable shaft; and a fan disposed on the second region of the outer surface of the rotatable shaft within the casing above the radial passage extending from the inner extremity of the bore proximate the casing, wherein the fan is disposed on the second region of the outer surface of the rotatable shaft on a portion that is radially above a portion on the first region of the outer surface where the coolant inlet is formed therein, the fan having a high pressure side facing the rotor body and the plurality of field windings of coils and a lower pressure suction side facing the casing, wherein movement of the fan creates a differential pressure that causes a flow of the coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into the coolant inlet and through the at least one radial passage near the end of the inner extremity of the bore and the axial bore to cool the conducting elements disposed therein, and into the radial passage extending from the inner extremity of the bore proximate the casing and through a discharge port formed therein to a coolant outlet formed on the outer surface of the rotatable shaft about the suction side of the fan.DRAWINGS

[0011] The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:

[0012] FIG. 1 shows an isometric view of a dynamoelectric machine such as an electrical generator according to the prior art;

[0013] FIG. 2 shows an isometric view of a more detailed view of an end section of an electrical generator where a fan differential pressure cooling structure can be utilized within this section according to an embodiment of the invention;

[0014] FIG. 3 shows a longitudinal section view of an electrical generator end with further details of the fan differential pressure cooling structure according to an embodiment of the invention, with only a half of the electrical generator end above a central axis being shown; and

[0015] FIG. 4 shows a longitudinal section view of the electrical generator end depicted in FIG. 3 with both halves about the central axis being shown according to an embodiment of the invention.DETAILED DESCRIPTION

[0016] Example embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments are shown. Indeed, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfyapplicable legal requirements. For like numbers may refer to like elements throughout.

[0017] This disclosure relates generally to dynamoelectric machines, and more specifically, to deploying a cooling structure for a dynamoelectric machine that is based on fan differential pressure. The cooling structure of the various embodiments includes an axial fan disposed on the outer surface of a rotatable shaft on which a rotor body having field windings of coils is mounted thereon. Movement of the fan creates a differential pressure that causes a flow of a coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into a coolant inlet and through various passages formed in the rotatable shaft to cool conducting elements disposed therein and out through a coolant outlet arranged on the outer surface of the rotatable shaft about the fan proximate a casing within which the rotor and a portion of the shaft are disposed.

[0018] Although the various embodiments are described with respect to an electrical generator, it is understood that these embodiments have applicability with other types of dynamoelectric machines. Examples of other dynamoelectric machines that the various embodiments may have applicability include, but are not limited to, electric motors and alternators.

[0019] Referring to the figures, FIG. 1 shows an isometric view of an electrical generator 10 according to the prior art. As shown in FIG. 1 , the electrical generator 10 includes a rotor body 12 that can be made of a ferrous metal material that is rotatably mounted on a shaft 14 via a bearing assembly (not illustrated). Arranged circumferentially about the mid-section of the rotor body 12 are a multiple of axially oriented slots 16 extending radially outward from a center of the rotor body. The slots are used for holding a multiple of field windings of coils 18 that can be made of copper or aluminum. These multiple of field windings of coils can include longitudinally oriented central windings 20 secured within the slots 16, and turns of endwindings 22 extending out from the slots 16 at axial ends 24 of the rotor body 12.

[0020] The shaft 14 of the electrical generator 10 can include a driven end 26 having a coupling 28 for a prime mover such as a gas turbine or a steam turbine that is operative to turn the shaft. The turning of the shaft 14 by the prime mover produces a rotating magnetic field within the machine. This induces a three-phase set of voltages with stator windings in a stator of the electrical generator 10 that encloses the rotor body 12. Both the stator and stator windings are not illustrated for purposes of clarity. The opposing end of the shaft 14, which can be referred to as the non-driven end 30, can include a coupling 34. An external source such as a generator excitation current source (not illustrated for purposes of clarity) can supply electrical current to the shaft 14. The electrical current passes internally through the shaft 14 via conductor or conducting elements to the field windings 18 in the rotor body 12. In this manner, the electrical current that passes from the generator excitation current source to the field windings 18 via the conducting elements can maintain the rotating electromagnetic field at a fixed polarity.

[0021] FIG. 2 shows an isometric view of a more detailed view of an end section of a dynamoelectric machine such as an electrical generator36 where a fan differential pressure cooling structure can be utilized within this section according to an embodiment of the invention. In this embodiment, as shown in FIG. 2, the electrical generator 36 can include a fan 66 oriented axially about the shaft 14 with a plurality of blades 67 arranged circumferentially around the shaft. As explained below in more detail, movement of the axial fan creates a differential pressure that causes a flow of a coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into a coolant inlet and through various passages formed in the rotatable shaft to cool conducting elements disposed therein and out through a coolant outlet arranged on the outer surface of the rotatable shaft about the fan proximate a casing within which the rotor and a portion of the shaft are disposed. It is noted that the endwindings of the coils are not depicted as these windings are secured by an annular retaining ring 90 fitted over the axial end 24 of the rotor body 12. In this manner, the annular retaining ring 90 can restrain the endwindings from radial outward movement by centrifugal forces produced by the rotor of the electrical generator rotor 36.

[0022] FIG. 3 shows a longitudinal section view of an end section of the electrical generator 36 according to an embodiment of the invention. The rotor body 12 of the electrical generator 36 including the field windings of coils secured thereabout are within a casing 38. Gas can be prevented from escaping from the casing 36 by a seal 40. The rotatable shaft 14 on which the rotor body 12 mounts thereon is depicted in FIG. 3 with an end 42 extending out from the casing 38. The shaft 14 includes an axial bore 44 extending between an inner extremity 46 of the bore that advances intothe rotor body and an outer extremity 48 of the bore that extends out from the rotor body 12 and through the casing 38.

[0023] A plurality of radial passages communicate with the axial bore 44. As shown in FIG. 3, the plurality of radial passages that communicate with the bore 44 can include at least one radial passage 50 near an end of the inner extremity 46 of the bore 44 extending to a first region 52 of an outer surface 54 of the rotatable shaft and a radial passage 56 extending from the inner extremity 46 of the bore 44 to a second region 58 of the outer surface of the rotatable shaft proximate the casing 38.

[0024] Conductors or conducting elements 60, such as copper or aluminum, are disposed internally in the shaft 14. As shown in FIG. 3, conducting elements 60 can be disposed longitudinally in the axial bore 44 from the outer extremity 48 to the inner extremity 46 of the bore. In addition, conductor elements 60 can be disposed in the at least one radial passage 50 between the inner extremity 46 of the bore and the outer surface 54 of the rotatable shaft 14 near the first region 52 of the outer surface.

[0025] FIG. 3 shows a main lead 62 extending axially from the conducting elements 60 in the at least one radial passage 50 near the first region 52 of the outer surface 54 of the rotatable shaft 14 to connect with the plurality of field windings of coils. In particular, the main lead 62 connects the conducting elements 60 in the at least one radial passage 50 to the endwindings 22 of the field windings of coils.

[0026] A coolant inlet 64 can be formed about the first region 52 ofthe outer surface 54 of the rotatable shaft 14 proximate the at least one radial passage 50, the main lead 62 and the endwindings 22 to receive a coolant fluid circulating in the casing 38 about the rotor body 12 and the rotatable shaft 14. The circulation of the coolant fluid in the electrical generator 36 is depicted in FIG. 3 by the thicker arrows. In one embodiment, the coolant fluid that can circulate within the electrical generator 36 about the stator and the rotor body can include hydrogen. It is understood that the cooling structure of the various embodiments described herein is suitable for use with other types of coolant fluids.

[0027] The electrical generator 36 of FIG. 3 can further include the fan 66 oriented axially about the shaft 14 with a plurality of blades 67 arranged circumferentially around the shaft. As shown in FIG. 3, the fan 66 can be disposed about the second region 58 of the outer surface 54 of the rotatable shaft 14 within the casing 38 above the radial passage 56 extending from the inner extremity 46 of the bore 44 proximate the casing 38. The fan 66 can have a high pressure side 68 facing the rotor body 12 and the field windings of coils and a lower pressure suction side 70 facing the casing 38. To this extent, with this cooling structure depicted in FIG. 3, movement of the fan 66 can create a differential pressure that causes a flow of the coolant fluid circulating about the rotor body 12 to be driven into the coolant inlet 64 and through the at least one radial passage 50 near the end of the inner extremity 46 of the axial bore 44 and into an axial passage 61 in the bore to cool the conducting elements 60 disposed therein. The coolant fluid flows through the axial passage 61 in the axial bore 44 to outside the casing 38 to a radial coolant passage formed in thebore outside of the casing proximate a location wherein an excitation current conducting element connected to the excitation current source 76 connects with the conducting elements 60 in the axial bore 44. An axial coolant return passage 78, that is in communication with the radial coolant passage 56 that extends from the inner extremity 46 of the bore 44 proximate the casing 38 and the radial coolant passage of the bore outside of the casing, can supply the coolant fluid from that radial coolant passage to the radial coolant passage 56. The coolant fluid can then flow through a discharge port 79 formed in the radial coolant passage 56 to a coolant outlet 80 arranged on the outer surface 54 of the rotatable shaft 14 about the suction side 70 of the fan 66.

[0028] In one embodiment, as depicted in FIG. 3, the circulation of the coolant fluid in the electrical generator 36 can be arranged such the fluid does not flow around the field windings of coils. To this extent, the coolant fluid that is received by the coolant inlet 64 and distributed out through the coolant outlet 80 via the radial coolant passage 56 is not “heated” by the field windings.

[0029] As shown in FIG. 3, the fan 66 can be disposed on the second region 58 of the outer surface 54 of the rotatable shaft 14 on a portion that is radially above a portion of the outer surface where the coolant inlet 64 is formed therein. For example, the fan 66 can be disposed radially above the coolant inlet 64 such that a base of the blades 67 of the fan are above an opening in the coolant inlet that is formed in the outer surface 54 of the rotatable shaft 14. This radial difference between the base of the blades 67 of the fan 66 disposed on the second region 58of the outer surface 54 and the opening of the coolant inlet 64 is identified in FIG. 3 by a radial height H. Another feature associated with having the fan 66 radially above the coolant inlet 64 as shown in FIG. 3 is that the base of the blades 67 of the fan are relatively axially aligned with a midline axis extending through the endwindings 22. With this configuration, the top portion of the blades 67 of the fan 66 can extend radially above the endwindings 22. A result of having the fan 66 radially above the coolant inlet 64 with these features is that this radial height difference between the fan and the coolant inlet facilities coolant fluid flow efficiency between the coolant inlet and the coolant outlet 80, necessitating less overall work for the fan during cooling of the electrical generator 36.

[0030] There are other features associated with the location of the fan 66 with respect to the other components of the electrical generator 36. For example, as shown in FIG. 3, the radial passage 56 extending from the inner extremity 46 of the bore 44 can be substantially radially coincident with the fan 66. Also, the discharge port 79 formed in the radial passage 56 can be radially coincident with the fan 66 as shown in FIG. 3.

[0031] FIG. 3 shows other features that can be beneficial to the cooling structure of the various embodiments. For example, as shown in FIG. 3, there can be a difference in the diameter between the coolant inlet 64 and the coolant outlet 80. In particular, the location of the coolant outlet 80 on the outer surface 54 of the rotatable shaft 14 can have a radial height that is greater than the location of the coolant inlet 64 on the outer surface of the rotatable shaft. This difference in the radial height of the coolant outlet 80 in comparison to the coolant inlet 64 equates with adifference in the diameter of the coolant outlet to the diameter of the coolant inlet with respect to the outer surface of the shaft, and is illustrated in FIG. 3 by the diameter difference reference D.

[0032] FIG. 3 also shows that a pocket 82 can be formed in the rotatable shaft 14 under the first region 52 of the outer surface 54 of the shaft about an end of the at least one radial passage 56 extending from the inner extremity 46 of the bore 44, the main lead 62 and the coolant inlet 80. As shown in FIG. 3, the pocket 82 can comprise a first pocket portion 84 extending axially along the rotatable shaft 14 towards a location that is under the plurality of field windings of coils (e.g., the endwindings 22) and a second pocket portion 86 extending axially along the rotatable shaft in an opposing direction towards the fan 66 and the casing 38. Both the first pocket portion 84 and the second pocket portion 86 can extend beyond an axial periphery of the at least one radial passage 50.

[0033] The use of certain features such as the axial fan 66, the difference in the diameter of the coolant outlet 80 to the diameter of the coolant inlet 64, and the pocket 82 collectively contribute to the cooling structure of the various embodiments ability to facilitate coolant fluid flow efficiency between the coolant inlet and the coolant outlet, necessitating less overall work for the fan. Further, these elements are advantageous to cooling in embodiments in which there is only one radial passage 50 that extends from near the end of the inner extremity 46 of the bore 44 to the outer surface 54 of the rotatable shaft 14. In this scenario, because only one radial passage 50 is utilized, there will be a reduced amount of conductor elements 60 (e.g., less copper) in the electrical generator 36.As a result, the cooling of the electrical generator 36 must be more efficient. The use of the axial fan 66, the difference in the diameter of the coolant outlet 80 to the diameter of the coolant inlet 64, and the pocket 82 operate in conjunction to maximize the flow of the coolant fluid (e.g., hydrogen) within the electrical generator 36.

[0034] In one embodiment, an insert 88 can be disposed on the inner walls of the axial passage 61 in the bore 44 near the end of the inner extremity 46 of the bore. The insert 88 is configured to provide support to the conducting elements 60 disposed in the at least one radial passage 50 near the end of the inner extremity 46 of the bore 44 that extends to the first region 52 of the outer surface 54 of the rotatable shaft 14. In one embodiment, the insert 88 can include a steel material. To this extent, the insert 88 can prevent stress breakage at a connection with the axial and radial conducting elements 60.

[0035] As noted above with respect to the excitation current source 76, an excitation current conducting element can extend from the excitation current source into the rotatable shaft 14 to connect with conducting elements 60 disposed in the axial bore 44. In this manner, the excitation current conducting element can carry the excitation current provided by the excitation current source 76 to the conducting elements 60 disposed in the axial bore 44. The conducting elements 60 in the axial bore 44 can carry the excitation current to the conducting elements disposed in the at least one radial passage 50 near the end of the inner extremity 46 of the bore. The conducting elements 60 in the at least one radial passage 50 can then carry the excitation current to the main lead 62and the field windings of coils in the rotor body 12.

[0036] FIG. 4 shows a longitudinal section view of the end of the electrical generator 36 depicted in FIG. 3 and discussed with respect thereto. The view of FIG. 4 differs from the one depicted in FIG. 3 in that both halves of the end of the electrical generator are shown and that fewer details of the halves are illustrated for purposes of clarity. Nevertheless, the details discussed above with respect to FIG. 3 are similarly applicable to FIG. 4.

[0037] From the description of the illustrated embodiments presented herein, it should be evident that the subject disclosure sets forth an improved cooling structure for a dynamoelectric machine, such as for example, an electrical generator, that is based on fan differential pressure. Movement of the fan creates a differential pressure that causes a flow of a coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into a coolant inlet and through various passages formed in the rotatable shaft to cool conducting elements disposed therein and out through a coolant outlet arranged on the outer surface of the rotatable shaft about the fan proximate a casing within which the rotor and a portion of the shaft are disposed. In this manner, the cooling structure of the various embodiments can keep “hotspot” temperatures about the components of the electrical generator to remain below a standard temperature value of insulation limits. For example, cooling structure of the various embodiments can keep the hotspot temperatures below 130 degrees Celsius.

[0038] In addition, the cooling structure of the various embodimentsallows a dynamoelectric machine, such as for example, an electrical generator, to be designed with conducting elements having high current density. This capability permits the electrical generator to use fewer conducting elements that are made of copper. Less copper translates with a decrease in the number of copper connections that is used within the internal components of the shaft. This equates with lower costs, quicker assembly of the electrical generator, less environment impact due to a reduced usage of copper, and potentially a design that is more suitable for use with a number of different generator structures ranging from simpler structures to more complex structures. This is in contrast to conventional conduction cooling solutions that utilize far more copper material as conducting elements and that are only able to manage considerably lower current densities, which is not ideal as power plant operators trend toward increasing capacity of electrical generators to operate at higher current densities.

[0039] The above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to beexhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize. For example, parts, components, steps and aspects from different embodiments may be combined or suitable for use in other embodiments even though not described in the disclosure or depictedin the figures. Therefore, since certain changes may be made in the above-described invention, without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.

[0040] In this regard, while the disclosed subject matter has been described in connection with various embodiments and corresponding figures, where applicable, it is to be understood that other similar embodiments can be used or modifications and additions can be made to the described embodiments for performing the same, similar, alternative, or substitute function of the disclosed subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single embodiment described herein, but rather should be construed in breadth and scope in accordance with the appended claims below. For example, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0041] In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, terms such as “first,” “second,” “third,” “upper,” “lower,” “bottom,” “top,” etc., if used, are merely labels, and are not intended to impose numerical or positional requirements on their objects. The terms “substantially,” “generally,” and“about” indicate conditions within reasonably achievable manufacturing and assembly tolerances, relative to ideal desired conditions suitable for achieving the functional purpose of a component or assembly. Further, the limitations of the following claims are not written in means-plus- function format and are not intended to be interpreted as such, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.

[0042] What has been described above includes examples of systems and methods illustrative of the disclosed subject matter. It is, of course, not possible to describe every combination of components or methodologies here. One of ordinary skill in the art may recognize that many further combinations and permutations of the claimed subject matter are possible. Furthermore, to the extent that the terms "includes," "has," "possesses," and the like are used in the detailed description, claims, appendices and drawings, such terms are intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. That is, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. Moreover, articles "a" and "an" as used in the subject specification and annexed drawings should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form. In addition, the phrase "one or more of" used before a listing of a number of possible options orrecitations is intended to mean any of the natural inclusive permutations. For example, "one or more of A and B" is satisfied by only A, only B, or both A and B.

[0043] This written description uses examples to disclose several embodiments of the invention, including the best mode, and also to enable one of ordinary skill in the art to practice the embodiments of invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to one of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0044] Further aspects of the invention are provided by the subject matter of the following clauses:

[0045] A dynamoelectric machine, comprising: a casing; a rotor body within the casing, the rotor body having a plurality of field windings of coils secured thereabout; a rotatable shaft on which the rotor body mounts thereon with an end extending out from the casing, the shaft having an axial bore extending between an inner extremity of the bore that advances into the rotor body and an outer extremity of the bore that extends out from the rotor body and through the casing, a plurality of radial passages communicating with the axial bore, with at least one radial passage near an end of the inner extremity of the bore extending to a first region of an outer surface of the rotatable shaft and a radial passage extending fromthe inner extremity of the bore to a second region of the outer surface of the rotatable shaft proximate the casing, conducting elements disposed longitudinally in the axial bore from the outer extremity to the inner extremity of the bore and conducting elements disposed radially in the at least one radial passage, a main lead extending axially from the conducting elements in the at least one radial passage near the first region of the outer surface of the rotatable shaft to connect with the plurality of field windings of coils, and a coolant inlet formed about the first region of the outer surface of the rotatable shaft proximate the at least one radial passage, the main lead and the plurality of field windings of coils to receive a coolant fluid circulating in the casing about the rotor body and the rotatable shaft; and a fan disposed on the second region of the outer surface of the rotatable shaft within the casing above the radial passage extending from the inner extremity of the bore proximate the casing, the fan having a high pressure side facing the rotor body and the plurality of field windings of coils and a lower pressure suction side facing the casing, wherein movement of the fan creates a differential pressure that causes a flow of the coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into the coolant inlet and through the at least one radial passage near the end of the inner extremity of the bore and the axial bore to cool the conducting elements disposed therein, and into the radial passage extending from the inner extremity of the bore proximate the casing and through a discharge port formed therein to a coolant outlet arranged on the outer surface of the rotatable shaft about the suction side of the fan.

[0046] The dynamoelectric machine of the preceding clause, wherein the fan is disposed on the second region of the outer surface of the rotatable shaft on a portion that is radially above a portion of the outer surface where the coolant inlet is formed therein.

[0047] The dynamoelectric machine of any of the preceding clauses, wherein a radial height difference between the fan and the coolant inlet facilities coolant fluid flow efficiency between the coolant inlet and the coolant outlet, necessitating less work for the fan.

[0048] The dynamoelectric machine of any of the preceding clauses, further comprising a pocket formed in the rotatable shaft under the first region of the outer surface of the shaft about an end of the at least one radial passage extending from the inner extremity of the bore, the main lead and the coolant inlet.

[0049] The dynamoelectric machine of any of the preceding clauses, wherein the pocket comprises a first pocket portion extending axially along the rotatable shaft towards a location that is under the plurality of field windings of coils and a second pocket portion extending axially along the rotatable shaft in an opposing direction towards the casing and the fan, both the first pocket portion and the second pocket portion extending beyond an axial periphery of the at least one radial passage.

[0050] The dynamoelectric machine of any of the preceding clauses, further comprising an insert disposed on inner walls of an axial passage in the bore near the end of the inner extremity of the bore.

[0051] The dynamoelectric machine of any of the precedingclauses, wherein the insert is configured to provide support to the conducting elements disposed in the at least one radial passage near the end of the inner extremity of the bore that extends to the first region of the outer surface of the rotatable shaft, wherein the insert prevents stress breakage at a connection with the axial and radial conducting elements.

[0052] The dynamoelectric machine of any of the preceding clauses, further comprising: an excitation current source located about the rotatable shaft; and an excitation current conducting element to connect the excitation current source with the conducting elements in the axial bore, wherein the excitation current conducting element carries the excitation current provided by the excitation current source to the conducting elements disposed in the axial bore, the conducting elements in the axial bore carrying the excitation current to the conducting elements disposed in the at least one radial passage near the end of the inner extremity of the bore, the conducting elements in the at least one radial passage carrying the excitation current to the main lead and the plurality of field windings of coils.

[0053] The dynamoelectric machine of any of the preceding clauses, further comprising an axial coolant return passage communicating with the radial passage extending from the inner extremity of the bore to the coolant outlet via the discharge port, wherein the axial coolant return passage is configured to receive a flow of the coolant fluid in the axial bore that emanates from the coolant inlet, and directs the flow of the coolant fluid to the radial passage extending from the inner extremity of the bore through the discharge port and out towards the coolant outlet.

[0054] The dynamoelectric machine of any of the preceding clauses, wherein the radial passage extending from the inner extremity of the bore is radially coincident with the fan.

[0055] The dynamoelectric machine of any of the preceding clauses, wherein the discharge port formed in the radial passage is radially coincident with the fan.

[0056] The dynamoelectric machine of any of the preceding clauses, wherein the coolant fluid comprises hydrogen.

[0057] A dynamoelectric machine, comprising: a casing; a rotor body enclosed within the casing, the rotor body having a plurality of field windings of coils secured thereabout; a rotatable shaft on which the rotor body mounts thereon with an end extending out from the casing, the shaft having an axial bore extending between an inner extremity of the bore that advances into the rotor body and an outer extremity of the bore that extends out from the rotor body and through the casing, a plurality of radial passages communicating with the axial bore, with at least one radial passage near an end of the inner extremity of the bore extending to a first region of an outer surface of the rotatable shaft and a radial passage extending from the inner extremity of the bore to a second region of the outer surface of the rotatable shaft proximate the casing, conducting elements disposed longitudinally in the axial bore from the outer extremity to the inner extremity of the bore and conducting elements disposed radially in the at least one radial passage, a main lead extending axially from the conducting elements in the at least one radial passage near the first region of the outer surface of the rotatable shaft to connect with theplurality of field windings of coils, and a coolant inlet formed about the first region of the outer surface of the rotatable shaft proximate the at least one radial passage, the main lead and the plurality of field windings of coils to receive a coolant fluid circulating in the casing about the rotor body and the rotatable shaft; and a fan disposed on the second region of the outer surface of the rotatable shaft within the casing above the radial passage extending from the inner extremity of the bore proximate the casing, wherein the fan is disposed on the second region of the outer surface of the rotatable shaft on a portion that is radially above a portion on the first region of the outer surface where the coolant inlet is formed therein, the fan having a high pressure side facing the rotor body and the plurality of field windings of coils and a lower pressure suction side facing the casing, wherein movement of the fan creates a differential pressure that causes a flow of the coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into the coolant inlet and through the at least one radial passage near the end of the inner extremity of the bore and the axial bore to cool the conducting elements disposed therein, and into the radial passage extending from the inner extremity of the bore proximate the casing and through a discharge port formed therein to a coolant outlet formed on the outer surface of the rotatable shaft about the suction side of the fan.

[0058] The dynamoelectric machine of the preceding clause, further comprising a pocket formed in the rotatable shaft under the first region of the outer surface of the shaft about an end of the at least one radial passage extending from the inner extremity of the bore, the main lead andthe coolant inlet, wherein the pocket comprises a first pocket portion extending axially along the rotatable shaft towards a location that is under the plurality of field windings of coils and a second pocket portion extending axially along the rotatable shaft in an opposing direction towards the casing, both the first pocket portion and the second pocket portion extending beyond an axial periphery of the at least one radial passage.

[0059] The dynamoelectric machine of any of the preceding clauses, wherein the radial passage extending from the inner extremity of the bore is radially coincident with the fan.

Claims

WHAT IS CLAIMED IS:

1. A dynamoelectric machine (36), comprising: a casing (38); a rotor body (12) within the casing, the rotor body having a plurality of field windings of coils (18) secured thereabout; a rotatable shaft (14) on which the rotor body mounts thereon with an end extending out from the casing, the shaft having an axial bore (44) extending between an inner extremity (46) of the bore that advances into the rotor body and an outer extremity (48) of the bore that extends out from the rotor body and through the casing, a plurality of radial passages communicating with the axial bore, with at least one radial passage (50) near an end of the inner extremity of the bore extending to a first region (52) of an outer surface (54) of the rotatable shaft and a radial passage (56) extending from the inner extremity of the bore to a second region (58) of the outer surface of the rotatable shaft proximate the casing, conducting elements (60) disposed longitudinally in the axial bore from the outer extremity to the inner extremity of the bore and conducting elements disposed radially in the at least one radial passage, a main lead (62) extending axially from the conducting elements in the at least one radial passage near the first region of the outer surface of the rotatable shaft to connect with the plurality of field windings of coils, and a coolant inlet (64) formed about the first region of the outer surface of the rotatable shaft proximate the at least one radial passage, the main lead and the plurality of field windings of coils to receive a coolant fluid circulating in the casingabout the rotor body and the rotatable shaft; and a fan (66) disposed on the second region of the outer surface of the rotatable shaft within the casing above the radial passage extending from the inner extremity of the bore proximate the casing, the fan having a high pressure side (68) facing the rotor body and the plurality of field windings of coils and a lower pressure suction side (70) facing the casing, wherein movement of the fan creates a differential pressure that causes a flow of the coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into the coolant inlet and through the at least one radial passage near the end of the inner extremity of the bore and the axial bore to cool the conducting elements disposed therein, and into the radial passage extending from the inner extremity of the bore proximate the casing and through a discharge port (79) formed therein to a coolant outlet (80) arranged on the outer surface of the rotatable shaft about the suction side of the fan.

2. The dynamoelectric machine (36) of claim 1 , wherein the fan (66) is disposed on the second region (58) of the outer surface (54) of the rotatable shaft (14) on a portion that is radially above a portion of the outer surface where the coolant inlet (64) is formed therein.

3. The dynamoelectric machine (36) of claim 2, wherein a radial height difference between the fan (66) and the coolant inlet (64) facilities coolant fluid flow efficiency between the coolant inlet and the coolant outlet (80), necessitating less work for the fan.

4. The dynamoelectric machine (36) of claim 1 , further comprising a pocket (82) formed in the rotatable shaft (14) under the first region (52) of the outer surface (54) of the shaft about an end of the at least one radial passage (50) extending from the inner extremity (46) of the bore, the main lead (62) and the coolant inlet (64).

5. The dynamoelectric machine (36) of claim 4, wherein the pocket (82) comprises a first pocket portion (84) extending axially along the rotatable shaft (14) towards a location that is under the plurality of field windings of coils (18) and a second pocket portion (86) extending axially along the rotatable shaft in an opposing direction towards the casing (38) and the fan (66), both the first pocket portion and the second pocket portion extending beyond an axial periphery of the at least one radial passage (50).

6. The dynamoelectric machine (36) of claim 1 , further comprising an insert (88) disposed on inner walls of an axial passage (61 ) in the bore (44) near the end of the inner extremity (46) of the bore.

7. The dynamoelectric machine (36) of claim 6, wherein the insert (88) is configured to provide support to the conducting elements (60) disposed in the at least one radial passage (50) near the end of the inner extremity (46) of the bore that extends to the first region (52) of the outer surface (54) of the rotatable shaft (14), wherein the insert prevents stressbreakage at a connection with the axial and radial conducting elements.

8. The dynamoelectric machine (36) of claim 1 , further comprising: an excitation current source (76) located about the rotatable shaft(14); and an excitation current conducting element to connect the excitation current source with the conducting elements (60) in the axial bore (44), wherein the excitation current conducting element carries the excitation current provided by the excitation current source to the conducting elements disposed in the axial bore, the conducting elements in the axial bore carrying the excitation current to the conducting elements disposed in the at least one radial passage (50) near the end of the inner extremity (46) of the bore, the conducting elements in the at least one radial passage carrying the excitation current to the main lead (62) and the plurality of field windings of coils (18).

9. The dynamoelectric machine (36) of claim 8, further comprising an axial coolant return passage (78) communicating with the radial passage (56) extending from the inner extremity (46) of the bore to the coolant outlet (80) via the discharge port (79), wherein the axial coolant return passage is configured to receive a flow of the coolant fluid in the axial bore (44) that emanates from the coolant inlet (64), and directs the flow of the coolant fluid to the radial passage extending from the inner extremity of the bore through the discharge port and out towards the coolant outlet.

10. The dynamoelectric machine (36) of claim 1 , wherein the radial passage (56) extending from the inner extremity (46) of the bore is radially coincident with the fan (66).11 . The dynamoelectric machine (36) of claim 10, wherein the discharge port (79) formed in the radial passage (56) is radially coincident with the fan (66).

12. The dynamoelectric machine (36) of claim 1 , wherein the coolant fluid comprises hydrogen.

13. A dynamoelectric machine (36), comprising: a casing (38); a rotor body (12) enclosed within the casing, the rotor body having a plurality of field windings of coils (18) secured thereabout; a rotatable shaft (14) on which the rotor body mounts thereon with an end extending out from the casing, the shaft having an axial bore (44) extending between an inner extremity (46) of the bore that advances into the rotor body and an outer extremity (48) of the bore that extends out from the rotor body and through the casing, a plurality of radial passages communicating with the axial bore, with at least one radial passage (50) near an end of the inner extremity of the bore extending to a first region (52) of an outer surface (54) of the rotatable shaft and a radial passage (56) extending from the inner extremity of the bore to a second region (58) of the outer surface of the rotatable shaft proximate the casing, conductingelements (60) disposed longitudinally in the axial bore from the outer extremity to the inner extremity of the bore and conducting elements disposed radially in the at least one radial passage, a main lead (62) extending axially from the conducting elements in the at least one radial passage near the first region of the outer surface of the rotatable shaft to connect with the plurality of field windings of coils, and a coolant inlet (64) formed about the first region of the outer surface of the rotatable shaft proximate the at least one radial passage, the main lead and the plurality of field windings of coils to receive a coolant fluid circulating in the casing about the rotor body and the rotatable shaft; and a fan (66) disposed on the second region of the outer surface of the rotatable shaft within the casing above the radial passage extending from the inner extremity of the bore proximate the casing, wherein the fan is disposed on the second region of the outer surface of the rotatable shaft on a portion that is radially above a portion on the first region of the outer surface where the coolant inlet is formed therein, the fan having a high pressure side (68) facing the rotor body and the plurality of field windings of coils and a lower pressure suction side (70) facing the casing, wherein movement of the fan creates a differential pressure that causes a flow of the coolant fluid circulating about the rotor body and the plurality of field windings of coils to be driven into the coolant inlet and through the at least one radial passage near the end of the inner extremity of the bore and the axial bore to cool the conducting elements disposed therein, and into the radial passage extending from the inner extremity of the bore proximate the casing and through a discharge port formed therein to a coolant outlet(80) formed on the outer surface of the rotatable shaft about the suction side of the fan.

14. The dynamoelectric machine (36) of claim 13, further comprising a pocket (82) formed in the rotatable shaft (14) under the first region (52) of the outer surface (54) of the shaft about an end of the at least one radial passage (50) extending from the inner extremity (46) of the bore, the main lead (62) and the coolant inlet (64), wherein the pocket comprises a first pocket portion (84) extending axially along the rotatable shaft towards a location that is under the plurality of field windings of coils (18) and a second pocket portion extending axially along the rotatable shaft in an opposing direction towards the casing, both the first pocket portion and the second pocket portion (86) extending beyond an axial periphery of the at least one radial passage.

15. The dynamoelectric machine (36) of claim 13, wherein the radial passage (56) extending from the inner extremity (46) of the bore (44) is radially coincident with the fan (66).

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