Claims:We Claim:
1. A high speed liquid cooled compact induction motor comprising:
a stator core (1) stacked is interposed between end plates (19, 20), wherein the stacked stator core (1) is provided with a multi-layer multi-phase stator winding having an overhang (17, 18) on each side of the end plates (19, 20);
a skewed rotor core (2) with a cage type rotor winding shorted at each end with the help of a drive end (DE) and a non-drive end (NDE) side end rings (15, 16);
a stator core assembly placed inside a frame (3) having a liquid coolant passage along with a coolant in pipe (22) and a coolant out pipe (23) to facilitate continuous coolant flow;
threaded holes (4) provided at a NDE side for placing a NDE cover (8), wherein threaded holes (5) are provided at a DE side for placing a DE cover (9);
a collar (6) on the frame (3) to mount the motor; and
a skewed rotor core along with a squirrel cage winding in a rotor assembly placed onto a rotor shaft (14).

2. The compact induction motor as claimed in claim 1, wherein the rotor shaft (14) is placed with the help of key and inserted inside the stator bore having an air gap (21) between each of them.

3. The compact induction motor as claimed in claim 1 or 2, wherein in the rotor, the slippage of bearings (12, 13) at each end is arrested with the help of bearing stoppers (10, 11) provided for each bearing and attached onto respective end cover.

4. The compact induction motor as claimed in claims 1-3, wherein the frame (3) has the DE and the NDE side covers (8,9) to complete the motor assembly.

5. The compact induction motor as claimed in claims 1-4, wherein the liquid coolant includes ethylene glycol, water, ethylene glycol water mixture.

6. The compact induction motor as claimed in claims 1-5, wherein said collar (6) with at least one hole (7) is placed on the frame (3) to mount the motor onto application.

7. The compact induction as claimed in claims 1-6, wherein the stator winding with optimum slot fill factor allowing bunching of circular shaped thin copper or copper alloy or silver or silver alloy based super enameled wires as coils and placing them inside the slot.

8. The compact induction as claimed in claims 1-7, wherein the rotor with the skewed trapezoidal bars with micron sized surface finish to have 100 to 200 micron size physical air gap between the stator and the rotor.

9. The compact induction motor as claimed in claim 1-8, wherein the induction motor has the non-drive end (NDE) cover (8, 9) having separate bearing holding arrangement for easier disassembly.
, Description:HIGH SPEED LIQUID COOLED COMPACT INDUCTION MOTOR
- FIELD OF INVENTION
[0001] The present disclosure, in general, relates to high speed liquid cooled compact induction motor. More particularly, the present invention relates to induction motor, liquid cooled induction motor, and high speed motors.

BACKGROUND OF INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] An induction motors are versatile and the most widely used motors across various industrial and domestic purposes for their inherent advantages over other type of motors. Usually a squirrel cage type induction motor is most preferable owing to easier manufacturing and lesser maintenance. The induction motors are also termed as an asynchronous motors as the speed of the motor is not strictly equal to synchronous speed (which is governed by the operating frequency and number of poles), rather little lesser (i.e. slip times) than the synchronous speed.
[0004] A stator of the induction motor is mostly similar to a synchronous machine, but the main constructional difference is in a rotor. There are two types of rotor configurations, one squirrel cage type and other wound rotor type. The most common configuration is the squirrel cage type because of its robust configuration. In the present invention, the squirrel cage type configuration has been adopted in a way suitable to high speed operation (upto 12000 RPM) along with better thermal performance.
[0005] When electrical machines are operated at very high rotational speeds, a large amount of centrifugal forces are generated. These forces have potential to permanently damage the motor. Hence, a proper rotor dynamic design must be in place to take care of these abnormalities. Also, a thermal management of the motor must be carried out in such a way that the losses generated in the motor are safely dissipated in the outside environment without having any adverse effect on the short-term and long-term performance of the motor. If proper thermal management is not kept in place in the motor, the elevated temperatures inside the motor may deteriorate the life and quality of the insulation of the motor.
[0006] The Chinese patent publication CN106464088A discloses Induction motor with transverse liquid cooled rotor and stator. An electric machine with fluid cooling. The electric machine includes a stator, the stator having a stator winding and a stator core having a plurality of stacked magnetic laminations, each of the laminations of the stator core having a plurality of apertures overlapping to form a plurality of stator fluid channels, a stator fluid channel of the plurality of stator fluid channels being not entirely axial. The electric machine further includes a rotor, the rotor having a shaft and a rotor core having a plurality of stacked magnetic laminations, each of the laminations of the rotor core having a plurality of apertures overlapping to form a plurality of rotor fluid channels, and a rotary fluid coupling in fluid communication with the rotor fluid channels. The rotor and the stator are configured to form a magnetic circuit comprising an air gap between the rotor and the stator.
[0007] Therefore, there is a requirement of high speed liquid cooled compact induction motor, which has been proposed by the present invention so as to serve the purpose effectively.

OBJECTS OF THE INVENTION
[0008] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0009] It is a general or primary object of the present disclosure to develop a high speed liquid cooled compact induction motor.
[0010] It is another object of the present disclosure to develop the compact induction motor with a single hard cure glued stator core encapsulating multi-layered multi-phase winding and skewed rotor core containing a squirrel cage made from a trapezoidal shaped bars.
[0011] Yet, another object of the present disclosure is to develop the compact induction motor having a lightweight aluminium alloy frame holding stator core along with winding and having liquid cooling channels inside it for better thermal management.
[0012] Yet, another object of the present disclosure is to develop a stator winding with optimum slot fill factor allowing bunching of circular shaped thin copper or copper alloy or silver or silver alloy based super enameled wires as coils and placing them inside the slot.
[0013] Yet, another object of the present disclosure is to develop the rotor with the skewed trapezoidal bars with micron sized surface finish so as to have 100 to 200 micron size physical air gap between stator and rotor.
[0014] Yet, another object of the present disclosure is to develop the compact induction motor with drive end (DE) cover having separate bearing holding arrangement for easier disassembly and O-ring along with groove to give dust and water ingress protection.
[0015] Further object of the invention is to develop the compact induction motor with non-drive end (NDE) cover having separate bearing holding arrangement for easier disassembly, O-ring along with groove to give dust and water ingress protection and wave spring for containing the axial expansions and ensuring the bearing loading.
[0016] Still another object of the present disclosure is to have high insulation strength in all electrical and instrumentation connections in complete assembly of the motor with continuous coolant flow in the frame channels.
[0017] These and other objects and advantages of the present disclosure will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present disclosure is illustrated.
SUMMARY OF THE INVENTION
[0018] This summary is provided to introduce concepts related to manufacturing of composite insulators for use as high speed liquid cooled compact induction motor. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0019] The compact induction motor according to present invention comprises a stator core, stacked using end plates together with a multi-layer multi-phase stator winding having an overhang on each side and skewed rotor core with a cage type rotor winding shorted at each end with the help of a DE and a NDE side end rings.
[0020] A stator core assembly is placed inside a frame having a liquid coolant (ethylene glycol or water or ethylene glycol water mixture) passage along with a coolant in pipe and a coolant out pipe to facilitate the continuous coolant flow.
[0021] Multitude of threaded holes are provided at a NDE side for placing a NDE cover. Whereas, threaded holes are provided at a DE side for placing a DE cover.
[0022] Holes along with a collar on the frame to mount the motor onto application, wherever necessary. In the rotor assembly, the skewed rotor core along with squirrel cage winding is placed onto a rotor shaft with the help of key and inserted inside the stator bore having a physical airgap between each of them.
[0023] In a rotor, the slippage of bearings at each end is arrested with the help of bearing stoppers provided for each bearing and attached onto respective end cover. The frame has DE and NDE side covers to complete the motor assembly.
[0024] 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
[0025] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0026] FIG. 1 shows a stator lamination with a slot fill details, in accordance with an embodiment of the present disclosure;
[0027] Fig. 2 shows a stator stack along with a stator winding, in accordance with an embodiment of the present disclosure;
[0028] Fig. 3 shows a complete stator assembly with a frame, in accordance with an embodiment of the present disclosure;
[0029] Fig. 4 shows a rotor lamination, in accordance with an embodiment of the present disclosure;
[0030] Fig. 5 shows a skewed rotor stack along with a squirrel cage, in accordance with an embodiment of the present disclosure;
[0031] Fig. 6 shows a complete rotor assembly, in accordance with an embodiment of the present disclosure;
[0032] Fig. 7 shows a DE side frame end cover, in accordance with an embodiment of the present disclosure;
[0033] Fig. 8 shows a NDE side frame end cover, in accordance with an embodiment of the present disclosure; and
[0034] Fig. 9 shows a complete motor assembly, in accordance with an embodiment of the present disclosure.
[0035] The figures depict embodiments of the present subject matter for illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF INVENTION WITH REFERENCE TO THE DRAWINGS OF THE PREFERRED EMBODIMENTS
[0036] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to con all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0037] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0038] The present invention relates to high speed liquid cooled compact induction motor. The induction motor has always been the most widely used prime-mover in all industrial and utility applications. Among various types and topologies, a squirrel cage type induction motor (wherein the rotor winding is in the form of squirrel cage) is commonly chosen for its well-known robust design and lesser maintenance. In the present invention, a stator of the induction motor employs a multi-layered multi-phase winding, whereas the rotor configuration is skewed a squirrel cage type with trapezoidal shape bars. A stator core is placed in a frame having liquid cooled channels to take away the heat generated inside the motor. This along with optimum electrical and magnetic loading makes the induction motor very compact in size. Also, in the present invention, the micron sized grinded surfaces and better rotor dynamic profile of the rotor allows the motor to be operated at very high speeds (upto 12000 RPM) without any vibrational problems. A drive end (DE) and a non-drive end (NDE) covers of the motor are better equipped to take care of any longitudinal thermal expansions. The airgap in the motor is very low (in the range of 100 to 200 micron) which allows the motor to give improved efficiency along with improved power factor.
[0039] FIG. 1 shows a stator lamination (101) of high speed liquid cooled compact induction motor with slot fill details, in accordance with an embodiment of the present disclosure. In an embodiment, the stator lamination (101) comprises one stator slot (102) and one stator teeth (103) in consecutive fashion across an inner periphery. On an outer periphery, one or more trapezoidal notch(es) (104) has been provided for assembly of the laminations one over the other. The zoomed in view of the slot highlights an inner slot insulation (105) over which multi-layered and multi-phase stator winding made of copper or copper alloy or silver or silver alloy or copper-silver alloy is placed. Each winding bunch has a few insulated bottom layer conductors (107) and a few insulated top layer conductors (108) each having a final insulation (106) over them. To protect the windings from falling apart from the slot, a wedge (109) is provided.
[0040] Fig.2 shows a stator stack (201) along with a stator winding of the motor. A stator bore (202) is the place for keeping a rotor by having a physical air gap between each of them. An outer periphery (203) of the stack is grinded to micron level so as to have better thermal contact with a frame. The stator stack (201) contains all required insulated laminations thus making the active length of the motor. The stack has a drive end (DE) side (204) and a non-drive end (NDE) side end plate (205) made of high strength non-magnetic material. After stacking the laminations, a multi-layer multi-phase stator winding (208) is placed which has some overhang length on each side i.e. a DE (206) and a NDE side (207) overhang length.
[0041] Fig.3 shows a complete stator assembly with a frame of the motor. In this, a stator core assembly has a stator core stack (301) along with a DE side (302) and a NDE side end plates (303). Inside the slots of the stator core stack, a multi-layer multi-phase stator winding (304) is placed. After completing the winding, the core assembly is placed inside a frame (305) having liquid coolant (ethylene glycol or water or ethylene glycol water mixture) passage along with a coolant in pipe (309) and a coolant out pipe (310) to facilitate the continuous coolant flow. A threaded holes (306) are provided at NDE side for placing NDE cover. Whereas a threaded holes (307) are provided at DE side for placing DE cover. There are one or more holes (308) on the frame to mount the motor onto application, wherever necessary.
[0042] Fig.4 shows a rotor lamination (401) along with its slot fill. The rotor lamination (401) comprises one rotor slot (402) and one rotor teeth (403) in consecutive fashion across an outer periphery. On an inner periphery, a key slot (404) is provided to assemble the complete rotor stack onto the shaft. The zoomed in view of a rotor slot (405) highlights that a rotor winding (406) made of trapezoidal bars does not have any electrical insulation.
[0043] Fig.5 shows a skewed rotor stack (501) along with a squirrel cage type rotor winding (507). A rotor bars are short circuited at each end with the help of a DE side (502) and a NDE side (503) end rings made of for example copper or copper alloy or silver or silver alloy or copper-silver alloy. On inner periphery, a key slot (504) is provided to assemble the complete rotor stack onto the shaft. A bore (505) of the rotor stack is grinded to micron level surface finish so as to have a firm grip with shaft after shrink fitting. Also, an outer periphery (506) of rotor stack is grinded to micron level surface finish so as to have a uniform air gap and lesser wind age losses at very high RPM operation.
[0044] Fig.6 shows a complete rotor assembly (601) of the motor. A skewed rotor core with a cage type rotor winding (602) shorted at each end with the help of a DE and a NDE side end rings (603, 604). The complete stack is mounted onto a rotor shaft (605) with the help of an integrated key on shaft fitted in the key slot of rotor stack. The rotor stack is pushed upto a rotor core stopper step (611) provided on the shaft. Each end of the shaft is provided with bearings viz. a NDE side bearing (606) and a DE side bearing (607). These both the DE and the NDE side bearings are push fitted on a bearing seating (608, 609) provided for each bearing on the shaft. A DE end (610) of the shaft is connected to the load or application.
[0045] Fig.7 shows a drive end side frame end cover (701). The DE side end cover (701) comprises holes (702) for assembling it to a frame. One or more through holes (703) are also provided to fasten the bearing stopper. A space (704) is provided for seating of outer race of bearing along with O-ring groove and wave spring. A space (705) is also provided for allen bolt head. A spigot (706) is also provided for alignment and better assembly of this end cover with frame.
[0046] Fig.8 shows a non-drive end side frame end cover 801. The NDE side end cover (801) comprises holes (802) for assembling it to a frame. One or more through holes (803) are also provided to fasten the bearing stopper. A space (804) is provided for seating of outer race of bearing along with O-ring groove. A space (805) is also provided for allen bolt head. A spigot 806 is also provided for alignment and better assembly of this end cover with the frame.
[0047] Fig.9 shows complete assembly of high speed liquid cooled compact induction motor. The compact induction motor comprises a stator core (1), stacked using end plates (19, 20), containing a multi-layer multi-phase stator winding having an overhang (17, 18) on each side and a skewed rotor core (2) with cage type rotor winding shorted at each end with the help of a DE and a NDE side end rings (15, 16).
[0048] The stator core assembly is placed inside a frame (3) having liquid coolant (such as ethylene glycol or water or ethylene glycol water mixture) passage along with coolant in a pipe (22) and a coolant out pipe (23) to facilitate the continuous coolant flow. A plurality of threaded holes (4) are provided at NDE side for placing NDE cover (8). Whereas a threaded holes (5) are provided at DE side for placing a DE cover (9). There are one or more holes (7) provided along with a collar (6) on the frame to mount the motor onto application, wherever necessary. Usually, the induction motors are used as prime movers for various types of loads or applications like pump, fan, conveyers, trolleys etc. The present invention relates to the frame of induction motor where the outer shell of application or load is required to be united with frame of induction motor or which can be directly assembled to the frame or body of application.
[0049] In a rotor assembly, the skewed rotor core along with a squirrel cage winding is placed onto rotor shaft (14) with the help of key and inserted inside the stator bore having physical air gap (21) between each of them. In the rotor, the slippage of a bearings (12, 13) at each end is arrested with the help of bearing stoppers (10, 11) provided for each bearing and attached onto respective end cover. The frame has a DE and a NDE side covers to complete the motor assembly.
[0050] The materials, coolant are given as example without restricting scope of the invention to the same. Thus, other materials, coolant readily apparent to a person skilled in the art are understood to be within purview of the invention.
[0051] Working of the invention: The induction motor of present invention has one stator and one rotor. When the stator of the induction motor is applied with suitable drive or controller, it excites the multi-layer multi-phase winding and created a rotating magnetic field (RMF) inside the stator bore. This stator produced RMF, then, interacts with the rotor windings and its associated magnetic field. The interaction of stator and rotor magnetic field makes the rotor spins on its axis and delivers the required electromagnetic torque to the application or load. The generated heat inside the induction motor is suitably dissipated to external environment partially via ambient and mostly via liquid coolant passed inside the motor frame.
[0052] 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 particulars 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). Furthermore, in those instances where a convention analogous to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). 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”.
[0053] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0054] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0055] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0056] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.