Cooling of end windings of a stator

Abstract

The present subject matter relates to a rotary machine (100) that includes a stator (102) that includes a stator core (104) and stator windings provided with end windings (106) arranged at two axial ends (120a; 120b). The stator core (106) includes a plurality of channels (108), each of the plurality of channels (108) extending parallel to a central axis (118) and open at the two axial ends (120a; 120b). The rotary machine (100) further includes a dispersal device (110) inserted in each of the plurality of channels (108) at either one or both the two axial ends (120a; 120b). The dispersal device (110) includes at least one spray hole (112) directed towards the end windings (106). The at least one spray hole (112) is adapted to disperse cooling medium to the end windings (106).

Description

COOLING OF END WINDINGS OF A STATORFIELD OF INVENTION

[0001] The present subject matter relates in general to cooling of a rotary machine, and particularly, to cooling of end windings of a stator in the rotary machine.BACKGROUND

[0002] Rotary machines are widely used in automotive applications and very much so as traction motor. Rotary machines typically include a stator and a rotor that are arranged coaxial to each other, the rotor being configured to rotate about a rotational axis. The stator and the rotor are disposed to face each other along the rotational axis in a housing. The rotor is mounted on a rotor shaft that extends out of the housing to mechanically interact with a pulley or a gear so that a transfer of torque is facilitated. In a known arrangement, the stator is supported by a bracket provided in the housing. In such an arrangement, the rotor is disposed within a cavity of the stator. Further, a gap is maintained between the outer periphery of the stator and the inner periphery of the bracket. Such a gap is particularly required in liquid cooled rotary electrical machine where a cooling medium is made to circulate through said gap. This gap functions as a channel to permit distribution of a cooling medium, such as oil, to cool the stator, specifically, to permit flow of the cooling medium to end windings of the stator.

[0003] In the conventional rotary machines, having the abovedescribed configuration, the cooling medium is made to flow in the channel and made to flow out, or sprayed, to the end windings at both ends of the stator. Such a configuration does not provide an even distribution of the cooling medium to the end windings. The end windings are not cooled inan efficient manner. Rotary machines of such configuration therefore tends to perform poorly and in an inefficient manner.

[0004] Therefore, the technical problem to be solved by the present subject matter is how to provide improved cooling of end windings of a stator in a rotary machine.SUMMARY OF THE INVENTION

[0005] The present subject matter seeks to solve the above- mentioned technical problem in conventional rotary electrical machines. The present subject matter has a particularly advantageous application in rotary electrical machines such as alternators, alternator-starters, or also reversible machines or electric motors. A reversible machine is a rotary electrical machine that can work reversibly, firstly as an electric generator in alternator function, and secondly as an electric motor, for instance, to start a thermal engine of a motor vehicle. The rotary electrical machine disclosed herein may also be applied as a traction motor for hybrid or electric vehicles.

[0006] The present subject matter relates to a rotary machine comprising: a stator, in coaxial arrangement to a rotor rotatable about a central axis common to the stator, and comprising a stator core and stator windings, the stator winding provided with end windings arranged at two axial ends of the stator core, wherein the stator core comprises: a plurality of channels formed through the stator core, each of the plurality of channels extending parallel to the central axis and open at the two axial ends; and a dispersal device inserted into each of the plurality of channels at either one or both the two axial ends, the dispersal device comprising at least one spray hole directed towards the end windings and adapted to disperse cooling medium to the end windings. Accordingly, by virtue of the at least one spray hole directed towards the end windings, the cooling medium is facilitated to flow in the plurality of channels and be distributed evenly onthe end windings. Particularly, the cooling medium is sprayed, or dispersed, to an outer diameter of the end windings. Cooling of the end windings is improved, thereby improving the performance of the rotary machine.

[0007] According to an aspect of the present subject matter, the dispersal device comprises: an insertion portion defining a partial length of the dispersal device inserted into one of the plurality of channels; and an exposed portion defining a second partial length of the dispersal device, the exposed portion being formed to comprise the at least one spray hole. Therefore, in a ‘mounted state’, the insertion portion of the dispersal device is inserted, or mounted, into one of the plurality of channels. Further, in said mounted state, the dispersal device is operational. The exposed portion of the dispersal device is cantilevered, thereby exposing the at least one spray hole to be directed towards the end windings (particularly, the outer diametric side of the end windings.

[0008] According to an example of the present subject matter, a first inner diameter defined in the insertion portion is equal to a second inner diameter defined in the exposed portion. Alternatively, the first inner diameter of the insertion portion is different to the second inner diameter of the exposed portion. For instance, the second inner diameter may be larger than the first inner diameter, thereby permitted larger volume of cooling medium to flow into the exposed portion facilitate more cooling medium to be dispersed. In a scenario where temperature generated at the end windings is high, an increased volume of cooling medium, as aforementioned, efficiently cools the end windings.

[0009] According to an example of the present subject matter, the exposed portion comprises one spray hole provided at a distal end of said exposed portion. The one spray hole is provided at a distal end of the exposed portion and is smaller than the second inner diameter of theexposed portion of the dispersal device. The distal end may accordingly be formed as a nozzle.

[0010] According to an example of the present subject matter, the exposed portion is inclined towards the central axis. Accordingly, the one spray hole is directed towards the end windings for an even spray of cooling medium.

[0011] According to another example of the present subject matter, the insertion portion and the exposed portion is formed as a straight tube extending in parallel to the central axis.

[0012] According to an aspect of the present subject matter, the exposed portion comprises an outer circumferential surface wherein multiple spray holes is arranged in a lattice of rows and columns, the columns being separated at regular intervals in a circumferential direction. The number of rows and columns may vary according to the size of the end windings and the amount of heat that is expected to be generated at the end windings. Meaning, a larger size of the end windings demands a lattice of more rows and / or columns to ensure an even spread of cooling medium to the end windings.

[0013] According to an aspect of the present subject matter, the insertion portion is press-fitted, or shrink fitted, or glued into one of the plurality of channel. Accordingly, the dispersal device is mountable in a simple manner.

[0014] According to an aspect of the present subject matter, the exposed portion comprises a flange extending from the outer circumferential surface, the flange being positioned adjacent to the insertion portion. The flange delimits the exposed portion from being inserted into one of the at least one channel. It is ensured, by virtue of the flange, that the exposed portion remains cantilevered and the at least onespray hole is exposed to permit cooling medium to spray, or disperse, evenly to the outer diametric side of the end windings.

[0015] According to an example of the present subject matter, the rotary machine comprises a shell in which the stator is disposed, wherein each of the at least one channel is formed by virtue of a space between an inner wall of the shell and on an outer surface of the stator core.BRIEF DESCRIPTION OF DRAWINGS

[0016] The features, aspects, and advantages of the present invention will be better understood with regard to the following description and accompanying figures. The description refers to the annexed drawings, wherein:

[0017] FIG. 1 illustrates a schematic cross-sectional view of a rotary machine, configured in accordance with an aspect of the present subject matter;

[0018] FIG. 2 illustrates an enlarged view at region A depicted in FIG. 1 , configured in accordance with the present subject matter;

[0019] FIG. 3 illustrates a top view of the rotary machine, configured in accordance with an aspect of the present subject matter;

[0020] FIG. 4A illustrates a cross-sectional view of a dispersal device for distribution of cooling medium in the rotary machine, configured in accordance with an example of the present subject matter;

[0021] FIG. 4B illustrates a cross sectional view of the distribution device in FIG. 4A;

[0022] FIG. 5A illustrates an isometric view of the dispersal device, configured in accordance with another example of the present subject matter;

[0023] FIG. 5B illustrates a cross-sectional view of the dispersal device in FIG. 5A; and

[0024] FIG. 6 illustrates a top view of the rotary machine, with the dispersal device of FIG. 5A and 5B mounted therein, said dispersal device being configured in accordance with an example of the present subject matter.

[0025] The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and / or examples consistent with the description, however, the description is not limited to the examples and / or examples provide in the drawings.DETAILED DESCRIPTION

[0026] In the description that follows, reference is made to accompanying drawings, which form part thereof, and in which is shown by way of illustration specific implementations in which the invention maybe practiced. These implementations are described in sufficient detail to enable that skilling in the art to practice the invention, and it is to be understood that the implementations may be combined, or that other implementations may be utilized, and that structural and logical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.

[0027] FIG. 1 illustrates a schematic cross-sectional view of a rotary machine 100, configured in accordance with the present subject matter. The rotary machine 100 includes a stator 102, in coaxial arrangement to a rotor rotatable about a central axis 1 18 that is common to the stator 102. The stator 102 includes a stator core 104 and stator windings provided withend windings 106 arranged at two axial ends 120a, 120b of the stator core 104. The stator core 106 includes a plurality of channels 108 formed through the stator core 104. Each of the plurality of channels 108 extend parallel to the central axis 1 18. Moreover, each of the plurality of channels is open at the two axial ends 120a, 120b. The rotary machine 100 further includes a dispersal device 1 10 inserted in each of the plurality of channels 108 at either one or both the two axial ends 120a, 120b. The dispersal device 100 includes at least one spray hole 112 that is directed to the end windings 106 of the stator 102. The at least one spray hole 1 12 is adapted to disperse cooling medium to the end windings 106.

[0028] During normal operation of the rotary machine 100, cooling medium (or, ‘cooling means’) enters the plurality of channels 108 and follows an axial path 1 16b towards the end windings 106 arranged at the two axial ends 120a, 120b. The cooling medium flows into the dispersal device 1 10 which disperses the cooling medium, via the at least one spray hole 112 towards the end windings 106. More particularly, the at least one spray disperses the cooling medium to an outer diametric side of the end windings 106, said outer diametric side referring to the outermost end of the end windings 106 in a radial direction from the central axis 1 18.

[0029] Within the meaning of the present subject matter:

[0030] “axial” or “axially” or “axial direction” refers to “a direction parallel to the central axis 1 18 that is common to the stator 102 and the rotor”;

[0031] “radial” or “radially” or “radial direction” means “a direction perpendicular to the central axis 1 18, or a direction perpendicular to any line parallel to the central axis 1 18; and

[0032] “circumferential” or “circumferentially” refers to ”a direction encircling a line, for instance, the central axis 1 18, or a line parallel to thecentral axis 1 18, or a direction encircling any surface that is at least substantially circularly shaped.

[0033] The stator 102 extends in length along the axial direction. The stator core 104 may be mounted (hence, supported) in a shell 114, for instance, by fasteners. According to an example of the present subject matter, the stator core 104 is a laminated stator core 104 that includes a plurality of stacked laminations (not shown), although it is permissible for the stator core 104 to be non-laminated. The stator core 104, in said example, includes a ferromagnetic material such as steel, although use of any one or more electrically conductive materials is permissible without departing from the scope of the present subject matter. Preferably, the stator core 104 includes a plurality of arcuately spaced apart, generally radially extending teeth. More particularly, each of the teeth includes a generally circumferentially extending yoke, a generally radial arm extending from the yoke, and a crown extending generally circumferentially from the arm. The stator windings is electrically conductive wiring wound multiple times about each tooth to form a plurality of turns or loops. The electrically conductive wiring is preferably formed of copper or aluminum, although any one or more of a variety of electrical conductive materials or a combination thereof may be used within the ambit of the present subject matter. Further, the wiring may be coated or uncoated. The wiring is wound around the teeth in a particular manner according to the configuration and desired performance characteristics of the rotary machine 100. Alternatively, the stator windings may be formed from isolated copper rods (or aluminum, or a combination thereof) in the form of what are referred to as pins, or U-pins, or hairpin.

[0034] In FIG. 1 , one of the plurality of channels 108 in the stator core 106 is shown. Said channel 108 is open at a first axial end 120a and a second axial end 120b. Further, two dispersal devices 1 10 are provided, one of the two dispersal devices 110 being inserted in the opening of thechannel 108 at the first axial end 120a; and the second of the two dispersal devices 1 10 being inserted in the opening of the channel 108 at the second axial end 120b. Both of the two dispersal devices 1 10 include at least one spray hole 1 12 that is directed towards the outer diametric side of the end windings 106. Therefore, during operation, cooling medium flows in the channel 108 along the axial path 1 16b, towards the first axial end 120a and the second axial end 120b, and accordingly enters the two dispersal devices 1 10. The at least one spray hole 112, provided in each of the two dispersal devices 1 10, facilitates the cooling medium to spray in an even manner to the outer diametric side of the end windings 106.

[0035] According to the example in FIG. 1 , the stator 102 is disposed in the shell 1 14. During operation, cooling medium enters the channel 108 via an orifice 122 formed in the shell 114. The orifice 122 in the shell permits cooling medium to enter the channel 108 in a radial path 1 16a. Following the radial path 1 16a, the cooling medium is then bifurcated in the channel 108 to flow in the axial path 1 16b towards the first axial end 120a and the second axial end 120b.

[0036] FIG. 2 illustrates an enlarged view of the rotary machine 100 at region A depicted in FIG. 1 , said rotary machine 100 configured in accordance with the present subject matter. FIG. 2 shows the dispersal device 1 10 in a ‘mounted state’ where the dispersal device 1 10 is inserted, or mounted, in the opening of the channel 108. In the example shown in FIG. 2, the dispersal device 1 12 includes multiple spray holes 1 12 arranged in a lattice of rows and columns. The columns are separated at regular intervals in a circumferential direction with respect to the dispersal device 1 10. A partial length of the dispersal device 1 10 is inserted into the channel 108, and a second partial length of the dispersal device 1 10 is cantilevered and has the multiple spray holes 1 12 provided therein. The multiple spray holes 1 12 is directed towards the outer diametric side of the end windings106, thereby configured to facilitate cooling medium from the channel 108 to spray evenly over said outer diametric side.

[0037] FIG. 3 illustrates a top view of the rotary machine 100 configured in accordance with the present subject matter. The stator core 104, as explained in the preceding description, includes plurality of channels 108. The plurality of channels 108 extend axially between the first axial end 120a and the second axial end 120b. The plurality of channels 108, provided in the stator core 104, is arranged in a circumferential manner about the central axis 1 18. Accordingly, the rotary machine 100 is provided with a plurality of dispersal devices 1 10, each of said plurality of dispersal devices 1 10 being mounted in the plurality of channels 108. Meaning, one dispersal unit 1 10 for one channel 108. Alternatively, each channel 108 is mounted with two dispersal devices 1 10, one dispersal device 100 at the first axial end 120a and the second dispersal device 100 at the second axial end 120b. Each of the plurality of devices 1 10 includes multiple spray holes 112 that are directed towards the outer diametric side of the end windings 106. Therefore, during operation, the cooling medium enters each of the dispersal devices 1 10 and sprayed to said outer diametric side via the multiples spray holes 1 12.

[0038] FIG. 4A is a cut section view of the dispersal device 1 10 taken from an axial plane cutting the dispersal device 1 10 in the axial direction between the first axial end 120a and the second axial end 120b, the dispersal device being configured in accordance with the present subject matter. FIG. 4B is another cut section view of the dispersal device 1 10 taken from a second plane perpendicular to the axial plane, the dispersal device 1 10 being configured in accordance with the present subject matter. For the sake of brevity, and due to similarities in reference numerals, the description that follows pertain to FIG.s 4A and 4B in tandem.

[0039] According to an aspect of the present subject matter, the dispersal device 1 10 includes an insertion portion 404 and an exposed portion 406. The insertion portion 404 defines a partial length L1 of the dispersal device 110, said insertion portion 404 mounted to the channel 108. The exposed portion 406 defines a second partial length L2 of the dispersal device 1 10. The exposed portion 406 includes at least one spray hole 112. In particular, multiple spray holes 402a are formed in the exposed portion 406, said multiple spray holes 402a being formed to disperse, or spray, cooling medium to the outer diametric side of the end windings 106. In particular, the multiple spray holes 402a is radially directed towards the outer diametric side of the end windings 106. The exposed portion 406 is supported by virtue of the insertion portion 404, and is therefore cantilevered.

[0040] In an example of the present subject matter, the insertion portion 404 has a first inner diameter d1. Further, in said example, the exposed portion has a second inner diameter d2. The first inner diameter d1 and the second inner diameter d2 defines an amount of cooling medium that is permitted through the insertion portion 404 and the exposed portion 406 respectively. In a non-limiting manner, the first inner diameter d1 has a value that is equal to a value of the second inner diameter d2. Therefore, during operation, flow of cooling medium through the dispersal device 1 10 is uniform across the partial length L1 and the second partial length L2. Alternatively, the first inner diameter d1 of the insertion portion 404 is different to the second inner diameter d2 of the exposed portion 406. For instance, the second inner diameter d2 may be larger than the first inner diameter d1 , thereby permitted larger volume of cooling medium to flow into the exposed portion 406 and be sprayed through the multiple spray holes 402a.

[0041] According to an example of the present subject matter, the exposed portion 406 further includes one spray hole 402b provided at adistal end 400, said distal end 400 being furthest from the insertion portion 404. The one spray hole 402b is direction in an axial direction. Therefore, during operation, the one spray hole 402b permits cooling medium to have an increased reach axially to cool the outer diametric side of the end windings 106. In an example, The one spray hole 402b is smaller than the second inner diameter d2 of the exposed portion 406 of the dispersal device 1 10. The distal end 400 may accordingly operate as a nozzle.

[0042] The dispersal device 1 10, of the example shown in FIG. 4A and 4B, is configured such that the insertion portion 404 and the exposed portion 406 is formed as a straight tube extending in parallel to the central axis 1 18. According to an aspect, the exposed portion 406 includes an outer circumferential surface 408 wherein the multiple spray holes 402a is arranged in the lattice of rows and columns. The columns are separated at regular intervals in a circumferential direction with respect to an axis 412 parallel to the central axis. The multiple spray holes 402a are directed towards the end windings 106. The arrangement of the multiple spray holes 402 is suitably arranged depending on the size of the end windings 106. For instance, in an example where the end windings 106 are large, the number of rows and / or columns of the multiple spray holes 402a may be increased. Alternatively, in said example, the separation between the columns of multiple spray holes 402a may be increased.

[0043] According to an example of the present subject matter, the dispersal device 1 10 includes a flange 410 extending from the outer circumferential surface 408. In particular, the flange 410 is formed on the exposed portion 404 and positioned adjacent to the insertion portion 404. The flange 410 arrests the exposed portion 404 from being inserted into the channel 108.

[0044] According to an aspect of the present subject matter, the dispersal device 110 is mounted, or inserted, into the channel 108 by wayof a press-fit. In particular, the insertion portion 404 is press-fitted into the channel 108 so that the dispersal device 1 10 is mounted. Alternatively, the dispersal device 1 10 is shrink fitted or glued into the channel 108.

[0045] FIG. 5A illustrates a dispersal device 500 configured in accordance with another example of the present subject matter. FIG. 5B is a cross sectional view of the dispersal device 500 configured in accordance with the example shown in FIG. 5A. For the sake of brevity, description that follows pertain to the aforementioned FIGs. 5A and 5B in tandem.

[0046] According to an aspect of the present subject matter, the dispersal device 500 includes an insertion portion 504 and an exposed portion 506. The insertion portion 504 defines a partial length L3 of the dispersal device 500, said insertion portion 504 configured to mount the channel 108. The exposed portion 506 defines a second partial length L4 of the dispersal device 500. The exposed portion 506 includes one spray hole 502. In particular, the one spray hole 502 is formed at a distal end 514 of said exposed portion 506, said distal end 400 being furthest from the insertion portion 404.

[0047] According to the example in FIG. 5A and 5B, the insertion portion 504 extends axially in a direction along a first axis 512a parallel to the central axis 1 18. Further, the exposed portion 506 extends in a direction along a second axis 512b inclined towards the central axis 1 18. The exposed portion 506 is supported by virtue of the insertion portion 504, and is therefore cantilevered. Accordingly, the arrangement of the one spray hole 502 at the distal end 514 facilitates flow of cooling medium in the direction at least substantially along the second axis 512b. The one spray hole 502 disperses cooling medium to the outer diametric side of the end windings 106.

[0048] In an example of the present subject matter, the insertion portion 504 has a first inner diameter d3. Further, in said example, theexposed portion 506 has a second inner diameter d4. The first inner diameter d3 and the second inner diameter d4 defines an amount of cooling medium that is permitted through the insertion portion 504 and the exposed portion 506 respectively. In a non-limiting manner, the first inner diameter d3 has a value that is equal to a value of the second inner diameter d4. Therefore, during operation, flow of cooling medium through the dispersal device 500 is uniform across the partial length L3 and the second partial length L4. Alternatively, the first inner diameter d3 of the insertion portion 504 is different to the second inner diameter d4 of the exposed portion 506. For instance, the second inner diameter d4 may be larger than the first inner diameter d3, thereby permitted larger volume of cooling medium to flow into the exposed portion 506 and be sprayed through the one spray hole 502.

[0049] In FIG. 5A and 5B, and the exposed portion 506 is configured such that the second axis 512b is inclined from the first axis 512a at an angle Q1 . The angle Q1 is preferably greater than 90 degree and smaller than 180 degree. Therefore, during operation, cooling medium flows into the dispersal device 500 in a straight line along the first axis 512a and is directed into the exposed portion 506 along the second axis 512b. Further, by virtue of the one spray hole 502, the cooling medium is dispersed to the outer diametric side of the end windings 106.

[0050] According to an example of the present subject matter, an the exposed portion 506 includes multiple spray holes (not shown) arranged in the lattice of rows and columns. In said example, the lattice of multiple spray holes is formed on an outer circumferential surface 508 of exposed portion 506. The columns are separated at regular intervals in a circumferential direction with respect to the second axis 512b. The multiple spray holes, in said example, are directed towards the end windings 106. The arrangement of the multiple spray holes is suitably arranged depending on the size of the end windings 106. For instance, in an example where the end windings 106 are large, the number of rows and / or columns of the multiple spray holesmay be increased. Alternatively, in said example, the separation between the columns of multiple spray holes may be increased.

[0051] According to an example of the present subject matter, the dispersal device 500 includes a flange 510 extending from the outer circumferential surface 508. In particular, the flange 510 is formed on the exposed portion 504 and positioned adjacent to the insertion portion 504. The flange 510 arrests the exposed portion 504 from being inserted into the channel 108.

[0052] FIG. 6 illustrates a top view of the rotary machine 100 wherein a plurality of the dispersal devices 500, configured in accordance with the example shown in FIG. 5A and 5B, is inserted in the plurality of channels 108. The stator core 104, as explained in the preceding description, includes plurality of channels 108. The plurality of channels 108 extend axially between the first axial end 120a and the second axial end 120b. The plurality of channels 108, provided in the stator core 104, is arranged in a circumferential manner about the central axis 1 18. Accordingly, the rotary machine 100 is provided with a plurality of dispersal devices 500, each of said plurality of dispersal devices 500 being mounted in the plurality of channels 108. Meaning, one dispersal unit 1 10 for one channel 108. Alternatively, each channel 108 is mounted with two dispersal devices 500, one dispersal device 500 at the first axial end 120a and the second dispersal device 500 at the second axial end 120b. Each of the plurality of devices 500 includes the one spray hole 502 that is directed towards the outer diametric side of the end windings 106. Therefore, during operation, the cooling medium enters each of the dispersal devices 1 10 and sprayed to said outer diametric side via the one spray hole 502.

[0053] According to an aspect of the present subject matter, the dispersal device 500 is mounted, or inserted, into the channel 108 by way of a press-fit. In particular, the insertion portion 504 is press-fitted into thechannel 108 so that the dispersal device 500 is mounted. Alternatively, the dispersal device 500 is shrink fitted or glued into the channel 108.

[0054] The rotary machine 100, configured in accordance with the examples shown in FIGs. 1 , 2, 3, 4A, 4B, 5A, 5B and 6, is suitably applicable for propulsion of a motor vehicle. The rotary machine 100 may operate in a motor mode in which an electrical current passes across the stator windings, and allows the creation of a magnetic field that causes a rotation of the rotor. When the rotary machine 100 is operating in a generator mode, the rotational movement of the rotor allows the creation of a magnetic field into the stator core 104, such magnetic field being turned into electrical current which passes across the stator windings of the stator 102 to ensure the power supply of various equipment in the motor vehicle.

[0055] In both examples of motor mode and generator mode, the plurality of channel 108 facilitate flow of cooling medium via the axial path 1 16b to reach the outer diametric side of the end windings 106. Further, by virtue of the dispersion device 1 10, 500, the cooling medium is dispersed, or sprayed, to the outer diametric side of the end windings 106.

[0056] In a non-limiting example, a groove is formed on the outer surface of the stator core 104. In said example, the groove operates as a channel for flowing cooling medium. The groove is configured as a semicircular groove or a U-shaped groove., The groove may alternatively form a partial channel, and a corresponding groove may be formed on the inner wall of the shell 1 14. Upon disposing the stator 102 into the shell 114, the groove and the corresponding groove coincide to fully form the channel through which cooling medium can flow. The stator core 104 may be shrink fitted into the shell 1 14, or mounted in the shell 1 14 by means of fasteners (not shown).

[0057] Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent topersons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the scope of the present subject matter is defined.

Claims

I / We Claim:1 . A rotary machine (100) comprising: a stator (102), in coaxial arrangement to a rotor rotatable about a central axis (1 18) common to the stator (102), and comprising a stator core (104) and stator windings provided with end windings (106) arranged at two axial ends (120a; 120b) of the stator core (104), wherein the stator core (106) comprises: a plurality of channels (108) formed through the stator core (104), each of the plurality of channels (108) extending parallel to the central axis (1 18) and open at the two axial ends (120a; 120b),; and a dispersal device (1 10; 500) inserted in each of the plurality of channels (108) at either one or both the two axial ends (120a; 120b), the dispersal device (1 10; 500) comprising at least one spray hole (1 12; 402a; 402b; 502) directed towards the end windings (106) and adapted to disperse cooling medium to the end windings (106).

2. The rotary machine (100), as claimed in the preceding claim, wherein dispersal device (1 10; 500) comprises: an insertion portion, (404; 504) defining a partial length (L1 ; L3) of the dispersal device (1 10; 500), inserted into one of the plurality of channels (108); and an exposed portion (406; 506) defining a second partial length (L4) of the dispersal device (1 10; 500), the exposed portion (406; 506) being formed to comprise the at least one spray hole (1 12; 402a; 402b; 502).

3. The rotary machine (100), as claimed in any one of the preceding claims, wherein a first inner diameter (d1 ; d3) defined in the insertion portion(404; 504) is equal to a second inner diameter (d2; d3) defined in the exposed portion (406; 506).

4. The rotary machine (100), as claimed in the preceding claim, wherein the exposed portion (406; 506) comprises one spray hole (402b; 502) provided at a distal end (400; 514) of said exposed portion (406; 506).

5. The rotary machine (100), as claimed in the preceding claim, wherein the exposed portion (406; 506) is inclined towards the central axis (1 18).

6. The rotary machine (100), as claimed in any one of claims 1 to 3, wherein the insertion portion (404; 504) and the exposed portion (406; 506) is formed as a straight tube extending in parallel to the central axis (1 18).

7. The rotary machine (100), as claimed in claim 5, wherein the exposed portion (406; 506) comprises an outer circumferential surface (408; 508) wherein multiple spray holes (1 12; 402a) is arranged in a lattice of rows and columns, the columns being separated at regular intervals in a circumferential direction.

8. The rotary machine (100), as claimed in any one of the preceding claims, wherein the insertion portion (404; 504) is press-fitted, or shrink fitted, or glued into one of the plurality of channels (108).

9. The rotary machine (100), as claimed claim 6 or 7, wherein the exposed portion (404; 504) comprises a flange (410; 510) extending from the outer circumferential surface (408; 508), the flange (410; 510) being positioned adjacent to the insertion portion (404; 504).

10. The rotary machine (100), as claimed in any one of the preceding claims, the rotary machine (100) comprising a shell (104) in which the statoris disposed, wherein each of the plurality of channels (108) is formed by virtue of a space between an inner wall of the shell (114) and an outer surface of the stator core (104).

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