A LIQUID COOLED STATOR JACKET FOR HIGH SPEED ROTATING MACHINES
FIELD OF INVENTION
[001] The present subject matter described herein, relates to a liquid cooled stator jacket for high speed rotating machines.
BACKGROUND AND PRIOR ART OF THE INVENTION
[002] Usually, the conventional rotating machines are naturally cooled or external fan cooled in typical industry environment. The outer surface of frame has several fins through which the heat generated in the machine is given off to external environment. The fins on frame body helps in increasing the surface area of frame, thereby, improving the overall ventilation of the motor. But, there is a limitation on transfer of heat from motor to external environment, beyond which motor shall not be operated.
[003] For better thermal management in high speed compact rotating machines, the stator ventilation needs to be modified. A better thermal management of the motor enables its operation for higher load capacities, as a result improving the utilization factor of the machine. If the stator frame is well-ventilated, as compared to conventional schemes, the stator windings can be operated at higher current densities, thus increasing the output of the machine.
[004] Few cares must be taken before realizing the improved stator ventilation. When liquid coolant based ventilation is to be adopted, the design with proper selection of materials and processes is very important. The pressurized liquid coolant must not enter from cooling system to electrically charged components of the motor, because it may lead to permanent damages in the motor. The manufacturing and assembly processes must be easily adoptable and should not give rise to process linked defects (e.g. pin-holes, blow-holes are associated with die-casting).

The manufacturing, assembly, disassembly, maintenance and repair of ventilation system should be easy. The surfaces of ventilation system should be chemically treated so that the coolant does not erode or corrode it. Also, there must be a good thermal contact between surfaces.
[005] Reference may also be made to the following prior arts:
[006] Prior art US5859482A describes the liquid cooled electric motor including stator frames having cast in place cooling conduits. The conduit is arranged in a generally helical configuration and the stator frame is cast around the conduit so that the conduit is embedded within, and integral with, the frame. Spacer, or stabilizer, bars are engaged to the conduit and provide support for the conduit and facilitate maintaining the desired spacing between lengths of conduit and between the conduit and the frame wall.
[007] Prior art US3504207A explains a rotor cooling system for a water-cooled turbogenerator that has a plurality of cooling channels arranged in the conductor of the rotor winding and a plurality of metal coolant tubes connected to the coil ends of the winding. These coolant tubes have parts extending radially inward into an annular metallic distribution vessel arranged axially outside the coil ends. Individual electrically insulating intermediate sleeves form a connection between the coolant tubes and the distribution vessel.
[008] Prior art JP4948542B2 relates to an electric machine including a stator and a rotor, wherein the stator has a cooling jacket that extends over at least a portion of the stator in the axial direction, and the cooling jacket surrounds the stator, and at least a portion thereof. The present invention relates to an electric machine having an outer jacket separated from each other. This cooling jacket is used in particular for increasing the output of the electric machine and for active temperature control, in particular a cooling jacket through which liquid is passed. Previously known cooling

solutions for electrical machines are based on a single radial or axial coolant flow through the cooling jacket or cooling tube.
[009] None of the above prior arts can fulfil the requirements of the invention for which it is designed. Hence, the present invention has been introduced.
OBJECTS OF THE INVENTION
[0010] It is therefore the object of the invention to overcome the aforementioned and other drawbacks in prior art.
[0011] The principal objective of the present invention is to provide for a liquid cooled stator jacket for compact high speed rotating machine.
[0012] Another object of the present invention is to develop a liquid cooled stator jacket having all inner and outer surfaces anodized for reducing various forms of erosion and corrosion of the jacket material and improving the overall life of the stator frame.
[0013] Another object of the present invention is to develop a liquid cooled stator jacket better thermal contact between stator core and frame and, thus, better thermal management of overall electrical machine.
[0014] Another object of the present invention is to develop a liquid cooled stator jacket allowing operation of stator winding with higher current density, thus, achieving higher power density in the machine with compact size and lesser weight.
[0015] Another object of the present invention is to develop a liquid cooled stator jacket suitable for high pressure coolant flow without any leakages or ingresses.
[0016] These and other objects and advantages of the present subject matter would be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with

accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION
[001] One or more drawbacks of the conventional technology based on existing apparatus and processes are overcome, and additional advantages are provided through a novel a liquid cooled stator jacket.
[002] Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[003] In accordance with an embodiment of the present subject matter, a
liquid cooled stator jacket for high speed rotating machine, comprises
plurality of mounting holes, plurality of cooling ducts/channels, an Inlet
port, an outlet port, an inner cylinder and an outer cylinder, wherein the
cooling ducts/channels are connected parallelly on outer surface of the
inner cylinder and on the inner surface of the outer cylinder.
[004] In another embodiment of the present subject matter, the coolant
flows through the inlet and outlet ports.
[005] In another embodiment of the present subject matter, the coolant
includes water/ethylene glycol/ethylene glycol water mixture.
[006] In another embodiment of the present subject matter, the jacket is
made of materials including aluminum alloy.
[007] In another embodiment of the present subject matter, the jacket has
a split cylinder structure.
[008] It is to be understood that the aspects and embodiments of the
disclosure described above may be used in any combination with each
other. Several of the aspects and embodiments may be combined to form a
further embodiment of the disclosure.

[009] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0010] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter, and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0011] Figure 1 illustrates a schematic view of Rotating electrical machine assembly in accordance with an embodiment of the present disclosure;
[0012] Figure 2 illustrates a schematic view of Stator assembly with frame in accordance with an embodiment of the present disclosure;
[0013] Figure 3 illustrates a schematic view of Inner cylinder of frame in accordance with an embodiment of the present disclosure;
[0014] Figure 4 illustrates of a schematic view of Cooling ducts on inner cylinder in accordance with an embodiment of the present disclosure;
[0015] Figure 5 illustrates a schematic view of Outer cylinder of frame in accordance with an embodiment of the present disclosure;

[0016] Figure 6 illustrates a schematic view of Cross section of frame after assembly in accordance with an embodiment of the present disclosure;
[0017] Figure 7 illustrates a schematic view of Machine frame assembly in accordance with an embodiment of the present disclosure;
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
[0018] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein are not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[0019] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0020] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition

of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0021] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0022] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0023] The present disclosure discloses a novel rotating electrical machine having a rotor, a stator and one liquid cooled jacket over stator. The liquid cooled jacket over the stator acts both as frame and ventilation system for the machine. The cooling ducts are in-built in the frame which carry the coolant (water/ethylene glycol/ethylene glycol water mixture). The machine frame is made by assembling and welding the two cylinders one over the other in which inner cylinder has one or more numbers of cooling ducts machined on its outer surface and the outer cylinder acts as containment wall for these cooling ducts. The complete system is pressure tested for its operation over a wide range of coolant pressures.
TECHNICAL ADVANTAGES:
[0024] The specialized anodizing carried over each surface of the liquid cooled jacket improves the operating life of the frame with lesser erosion and corrosion.

[0025] The liquid cooled jacket over the stator makes the electrical machine more thermally stable and allows the operation of stator winding with higher current density, thereby, improving the power density of the machine.
[0026] The liquid cooled stator jacket is manufactured using split cylinder design for ease of manufacturing, assembly, disassembly, maintenance and repair.
[0027] The liquid cooled stator jacket has better thermal contact between stator core and frame and, thus, better thermal management of overall electrical machine.
[0028] The liquid cooled stator jacket allows operation of stator winding with higher current density, thus, achieving higher power density in the machine with compact size and lesser weight.
[0029] The liquid cooled stator jacket is suitable for high pressure coolant flow without any leakages or ingresses.
[0030] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0031] With reference to Figure 1 to Figure 7, the present disclosure discloses a liquid cooled stator jacket for high speed rotating machines. [0032] With reference to Figure 1 illustrating the assembly 101 of a high speed typical rotating electrical machine. The assembly has one stator assembly 102 and one rotor assembly 103. The rotor assembly is made to roll over DE and NDE bearings 106, 107. The complete motor assembly is contained by DE and NDE covers 104, 105 along with a sealing plate 109

placed on NDE cover. There is a flange 108 connected to DE side of rotor shaft.
[0033] With reference to Figure 2 the stator assembly with frame. The stator assembly 201 primarily has stator core 202 and stator winding 203 along with frame. The stator frame 205 has a step 204 which acts as a stopper for stator core. There are more than one axial and radial cooling ducts 206 terminated at two ports in the frame. The coolant enters through inlet port 207 and exits through the outlet port 208 to facilitate the continuous flow. On non-drive end (NDE) side, there are series of tap holes 209 for assembling non drive end cover. Similarly, on drive end (DE) side, there are series of tap holes 210 for assembling drive end cover. On all four corners of DE side of frame, there are series of frame mounting holes 211. In present invention, the frame is fabricated using split cylinder assembly by assembling and welding inner and outer cylinders.
[0034] With reference to Figure 3 illustrating the inner cylinder of frame 301. Inner cylinder looks like a hollow cylinder with a flange integrated to it at one end. The inner cylinder has a step 305 which acts as a stopper for stator core. On outer cylindrical surface of this cylinder, there are more than one axial and radial cooling ducts 302. On the other hand, on inner cylindrical surface 303, the stator core sits and make a thermal contact with it. There are two slanted cuts 304 which on integration with outer cylinder makes a V-groove for welding. On flange side, there are series of tap holes 306 for assembling drive end cover. On all four corners of flange 308, there are series of frame mounting holes 307.
[0035] With reference to Figure 4 illustrating the axial cooling ducts on inner cylinder 401. The cold coolant 408 enters the inlet port and hot coolant 409 exits the outlet port. There are series of inlet 402 and outlet 404 ducts making the path 407 of coolant terminating at inlet 403 and outlet 405 markings respectively. Inlet and outlet markings are provided

to highlight the placement of inlet and outlet ports respectively. There is a flange 406 attached to inner cylinder for mounting the frame.
[0036] With reference to Figure 5 illustrating the outer cylinder of frame 501. The outer cylinder is guided and mounted over the inner cylinder for frame assembly. The inner surface 505 of this cylinder is interference fitted with inner cylinder, whereas the outer surface 504 is machined and exposed to external environment. There are two slanted cuts 502 which on integration with inner cylinder makes a V-groove for welding. On one side, there are series of tap holes 503 for assembling non-drive end cover.
[0037] With reference to Figure 6 illustrating the cross-section of the frame 601 assembly. After interference fitting of inner and outer cylinders 603, 604, V-grooves are welded and filled with parent material 602. Now, the cooling ducts are not visible from outside. The frame cooling ducts 605 are terminated at inlet and outlet ports 606, 607. On non-drive end (NDE) side, there are series of tap holes 610 for assembling drive end cover. Similarly, on drive end (DE) side, there are series of tap holes 609 for assembling drive end cover. On all four corners of DE side flange 608 of frame, there are series of frame mounting holes 611.
[0038] With reference to Figure 7 illustrating the front view and cross-sectional view of axial duct frame assembly. The coolant inlet 703 and outlet 704 ports extends cooling ducts 702 to external coolant flow arrangement. After assembling the frame, machining is done and few non-destructive tests are also carried out. Among them, ultrasonic test, pressure test and X-ray test is essentially done to assess any abnormality or defect. Later on, the complete frame assembly is surface anodized to reduce the probabilities of erosion and corrosion. The frame through its flange 706 can be mounted using frame mounting holes 701. The DE and NDE covers can be bolted at respective tap holes 705, 707 on the frame.
[0039] Working of invention

[0040] The present invention relates to a liquid cooled stator jacket for high speed rotating machines. The jacket has several ducts/channels embedded inside the jacket for allowing the coolant to flow through them. The cold coolant enters the inlet port and takes up the generated heat in the machine. The hot coolant exits from the outlet port. As the stator assembly is placed inside the jacket, the heat generated in the machine during operation is transferred to the coolant through various thermal contacts. This makes the machine compact, thermally better managed. Also, this allows the machine to operate at higher electrical current densiti

[0041] REFERENCE NUMERALS:
Reference Numeral Description
101 Machine assembly
102 Stator assembly
103 Rotor assembly
104 DE cover
105 NDE cover
106 DE bearing
107 NDE bearing
108 DE side flange
109 NDE sealing plate
201 Stator assembly
202 Stator core
203 Stator winding
204 Stator core step

205 Stator frame
206 Frame cooling ducts
207 Coolant inlet
208 Coolant outlet
209 Tap holes for NDE cover mounting
210 Tap holes for DE cover mounting
211 Frame mounting holes
301 Inner cylinder of frame
302 Frame cooling ducts
303 Inner surface
304 Cut for welding joints
305 Stator core step
306 Tap holes for DE cover mounting
307 Frame mounting holes
308 Frame mounting flange
401 Inner cylinder
402 Inlet ducts
403 Inlet marking
404 Outlet ducts
405 Outlet marking
406 Frame mounting flange
407 Coolant flow path
408 Cold coolant

409 Hot coolant
501 Outer cylinder of frame
502 Cut for welding joints
503 Tap holes for NDE cover mounting
504 Outer surface
505 Inner surface of outer cylinder
601 Machine frame
602 Welding joint
603 Inner cylinder
604 Outer cylinder
605 Frame cooling ducts
606 Coolant inlet
607 Coolant outlet
608 Frame mounting flange
609 Tap holes for DE cover mounting
610 Tap holes for NDE cover
611 Frame mounting holes
701 Frame mounting holes
702 Cooling ducts
703 Coolant inlet
704 Coolant outlet
705 Tap holes for DE cover mounting
706 Frame mounting flange

707 Tap holes for NDE cover
[0042] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should

be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0043] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0044] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations, which fall within the scope of the present subject matter.

We Claim:
1. A liquid cooled stator jacket (700) for high speed rotating
machine, the stator jacket (700) comprises:
plurality of mouting holes (701);
plurality of cooling ducts/channels (702);
an inlet port (703);
an outlet port (704);
an inner cylinder (603); and
an outer cylinder (604),
wherein the cooling ducts/channels (702) are connected serially on outer surface of the inner cylinder (603) and contained within the outer cylinder (604),
wherein the mounting holes (701) are on outer surface of the outer cylinder (604) for bolting and mounting the stator jacket (700) over stator of a machine.
2. The liquid cooled stator jacket (700) for high speed rotating machine as claimed in claim 1 , wherein coolant flows in through the inlet port (703) to enter the cooling ducts/channels (702).
3. The liquid cooled stator jacket (700) for high speed rotating machine as claimed in claims 1 to 2 , wherein coolant flows out through the outlet port (704) to exit the cooling ducts/channels.
4. The liquid cooled stator jacket (700) for high speed rotating machine as claimed in claims 1 to 3, wherein the coolant includes water/ethylene glycol/ethylene glycol water mixture.

5. The liquid cooled stator jacket (700) for high speed rotating machine as claimed in claims 1 to 4, wherein the stator jacket (700) is made of materials including aluminum alloy.
6. The liquid cooled stator jacket for high speed rotating machine as claimed in claims 1 to 5, wherein the stator jacket (700) has a split cylinder structure.
7. The liquid cooled stator jacket for high speed rotating machine as claimed in claims 1 to 6, wherein the outer cylinder (604) is guided and mounted over the inner cylinder (603) through welding.