Header that guides the flow of fluid into the cooling channels of a high-density motor and the flow of fluid out of the cooling channels

Abstract

A header for an electric machine including a stator core and one or more windings including a coolant passage formed therein. The header includes an inlet for receiving coolant, an outlet for the coolant to exit the header, an inlet plenum fluidly connected to the inlet, and an outlet plenum fluidly separated from the inlet plenum and fluidly connected to the outlet. The inlet plenum and the outlet plenum each have a different, varying cross-section from a top of the header as compared to a bottom of the header.

Description

Technical Field

[0001] The subject matter disclosed herein relates to an electromechanical machine. More specifically, the subject matter disclosed herein relates to a header for supplying a cooling fluid to a stator of a high-density electric motor.

Background Art

[0002] A typical liquid-cooled electromechanical machine / motor includes a rotor having a core and one or more rotor windings (conductors) extending through the core. In some machines, namely permanent magnet machines, the rotor windings are replaced by a plurality of permanent magnets. The rotor is surrounded by a stator, and there is an air gap between the rotor and the stator.

[0003] Similarly, the stator includes a stator core through which one or more stator windings pass. High power density electromechanical machines (generators or motors) generate intense resistive heating of both the stator and rotor windings, as well as eddy current and magnetic hysteresis heating in the cores of the rotor and stator.

[0004] Common methods of stator cooling include end turn spraying and methods that utilize heat conduction to a housing or fluid medium cooled through a back iron.

[0005] For example, the thermal management of conventional motors is often done in the form of external fins or liquid cooling jackets. Such systems typically direct a coolant through one or more channels within a back iron (housing) radially outside the stator core. However, these cooling methods only cool the outer perimeter of the stator core in the radial and axial directions. Thus, hot spots in the stator windings can occur along the axial centerline of the stator core.

Summary of the Invention

Means for Solving the Problems

[0006] Disclosed is a header for an electrical machine including a stator core and one or more windings having coolant passages formed therein. The header includes an inlet for receiving coolant, an outlet through which the coolant exits the header, an inlet plenum fluidly connected to the inlet, and an outlet plenum fluidly separated from the inlet plenum and fluidly connected to the outlet. The inlet plenum and the outlet plenum each have a different, varying cross-section from the upper part of the header compared to the bottom of the header.

[0007] In any of the foregoing embodiments, the inlet plenum and the outlet plenum may be in the same plane side by side and spaced apart parallel to each other.

[0008] In any of the foregoing embodiments, the inlet is a main inlet, the outlet is a main outlet, the header includes a front face and a back face, and the header is formed on the back face of the header such that coolant entering the main inlet can enter the inlet plenum and exit the header, and a plurality of outlet passages fluidly communicating with the inlet plenum, and formed on the back face of the header such that coolant exiting through the outlet passages and passing through a part of the motor can exit the outlet plenum, and may further include a plurality of inlet passages fluidly communicating with the outlet plenum.

[0009] In any of the foregoing embodiments, the inlet plenum includes an orifice plate disposed inside that divides the inlet plenum into a plenum inlet side and a plenum outlet side.

[0010] In any of the foregoing embodiments, the orifice plate includes a plurality of holes therein.

[0011] In any of the foregoing embodiments, the size of the holes varies from the upper part of the header to the bottom of the header.

[0012] In any of the foregoing embodiments, the coolant is received into the inlet plenum on the plenum inlet side, enters the plenum outlet side through the holes, and exits the header through the outlet passages.

[0013] In any of the foregoing embodiments, at least one of the plurality of outlet passages is connected to another one of the plurality of outlet passages by a first crossover section.

[0014] In any of the foregoing embodiments, at least one of the plurality of inlet passages is connected to another one of the plurality of outlet passages by a second crossover section.

[0015] In any of the foregoing embodiments, the inlet and outlet are arranged to receive and discharge the coolant along the axial direction of the header.

[0016] In any of the foregoing embodiments, the inlet and outlet are arranged to receive and discharge the coolant along the tangential direction of the header.

[0017] In any of the foregoing embodiments, the inlet and outlet are arranged to receive and discharge the coolant along the vertical direction of the header.

[0018] Also disclosed is a motor including a rotor, a stator, and a header of any of the foregoing embodiments. The header is arranged with respect to the motor to supply the coolant received at the inlet plenum to the motor and receive the coolant returned from the motor to the outlet plenum.

[0019] The header can comprise a coolant stator winding or a winding separator.

[0020] The subject matter regarded as the invention is pointed out with particularity and distinctly claimed in the concluding claims of this specification. The foregoing and other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0022] In the detailed description, embodiments of the invention will be described by way of example with reference to the drawings, together with advantages and features.

[0023] As the motor becomes more compact, another way to cool the stator may be beneficial. Disclosed herein is a header that can be used in one such method. For example, the header can be used to supply and direct a refrigerant to channels formed within or near the stator. The channels may be inside the stator windings or may be channels embedded in winding separators disposed between the windings. Further, in one embodiment, the channels can be provided in the stator teeth. That is, the separator can be a separate element, the stator teeth, or both.

[0024] In one embodiment, a header is disclosed that directs a cooling fluid, such as a refrigerant, to the windings and / or winding separators of an electromechanical stator and receives the fluid returning from the windings / separators.

[0025] The header may be generally circular and may include both an input plenum and an output plenum. In one embodiment, the plenums are eccentric. In one embodiment, the plenums can have various cross-sections. In one embodiment, the plenums are arranged side by side (parallel). In another embodiment, one plenum surrounds the other and they are in substantially the same plane. Other variations and configurations will be understood from the following description. Any or all of the embodiments herein can help provide a uniform flow of cooling fluid into and out of the cooling channels.

[0026] Further, in another embodiment, instead of a cooling flow, the header can be arranged to be in thermal conductive contact with one or more heat pipes disposed in any of the channels described above.

[0027] FIG. 1 shows a schematic cross-sectional view of an electric motor 100 into which an embodiment of the present disclosure can be incorporated. Although the rotor magnet is shown to be external to or outside the stator, the orientation can be reversed. Further, the teachings of this specification can be applied in the context where the magnet is U-shaped and surrounds both the inner and outer portions of the stator.

[0028] More particularly, FIGS. 1 and 2 respectively show a cross-sectional view of the electric motor 100 and a perspective view of a simplified stator core 104. The electric motor 100 includes a stator 102 that surrounds a rotor shaft 142 and is configured not to rotate with the rotor shaft 142.

[0029] The stator 102 includes a stator core 104 and one or more stator windings 110 supported or held by the core 104. In one embodiment, the windings can be formed as individual potted litz wire windings. The stator core 104 includes a ring hub 106 and a plurality of teeth 108 extending outwardly from the ring hub 106. Adjacent teeth 108 form stator slots 112 in which one or more stator windings can be disposed. That is, each slot can have a single stator winding 110 disposed therein or can include more than one winding as shown in the following further examples.

[0030] The motor 100 also includes a rotor 140. The rotor shown in FIG. 1 includes a rotor shaft 142 that rotates about a rotation axis 144. The rotor 140 also includes a magnet holding structure 146 connected to the shaft 142. The structure 146 holds one or more permanent magnets 148.

[0031] As shown in the figure, the stator 102 (and the winding 110 held by the stator 102) is disposed radially inward of the rotor magnet 148 with respect to the rotation axis 144, and a radial gap 150 is disposed between the rotor 140 and the stator 104. As shown in the figure, the rotor 140 is attached to the shaft 110 by the structure 146. In the "motor" mode in which current is applied to the winding 110, the current interacts with the magnet 148 to rotate the magnet / structure, causing rotation of the rotor shaft 142 about the axis 144 so that the shaft 142 can provide motive power for the load. Alternatively, in the "generator" mode, the shaft 142 can be driven so that current flows through the winding 110 due to the interaction of the magnets to drive an electrical load.

[0032] The stator core 104 can be formed from a plurality of axially laminated stacks laminated along the rotation axis 144. In some embodiments, the stacks 116 are formed from steel, although those skilled in the art will readily understand that other materials can be utilized. In alternative embodiments, the stator 104 can be formed as individual stator sections, as is known in the art.

[0033] The stator winding 110 includes a core segment 110a extending through the stator core 104 and an end turn segment 110b extending from each axial stator end of the stator core 104, as shown in the figure. As described above, when the stator winding 110 is excited by current, the resulting magnetic field drives the rotation of the rotor 140 about the rotation axis 144.

[0034] As shown in FIGS. 1 and 2, an electric motor may require cooling due to a high-density configuration, various operating parameters, or other reasons. For example, high-power density aerospace-class electric motors and drives may require advanced cooling techniques to ensure proper operation of the motor / drive. These machines generally have thermal limitations at high power ratings, and performance can be improved by relaxing these thermal limitations. To maintain a desired temperature, a thermal management system (TMS) that provides cooling to the components of the system is incorporated into the system. When installed in an aircraft, the power requirements, i.e., the load on the thermal management system (TMS), increase significantly during takeoff. If the size of the TMS is determined according to takeoff conditions (i.e., maximum load), the weight of the TMS becomes heavy to handle such a load. As a result, the weight becomes heavy and the output density decreases during cruise when such a load does not occur. Therefore, a TMS with a high cooling capacity is not necessary. In such aerospace applications, it is important to balance weight constraints and thermal load capacity.

[0035] This specification discloses channels in various parts of the stator assembly, as well as a header that feeds a coolant into these channels and receives the "heated" coolant returned from the channels. In one embodiment, the channels are formed in the winding 110. In another embodiment, the channels are formed in a separator (described below) disposed between the windings. Of course, embodiments can also include situations where channels are formed in both the windings and the separator.

[0036] FIGS. 3A and 3C respectively show top views of an exemplary winding 110 and separator 350. One or more of the windings 110 can be disposed in the stator slots 112 (FIG. 2). In some cases, the separator 350 is disposed between some or all of the windings 110.

[0037] The winding 110 includes a winding body 302. In one embodiment, the body 302 includes wire strands 305 that are supported or held by a substrate 306. The strands may be formed wire, ordinary wire, or Litz wire. In one embodiment, the substrate 306 may be a non-conductive material. In one embodiment, the substrate 306 may be a potting material.

[0038] A coolant passage 304 is also encapsulated within the body 302. The coolant passage 304 can be formed as a separate element or as a tube formed by the substrate 306. Note in FIG. 3A that there is an opening region 312 in the substrate 306. This region can be omitted in one embodiment. This region can be filled by the stator teeth during use.

[0039] As shown in FIG. 3B, the wire strands 305 can be localized in a region 350 within the body 302. The passage 304 is disposed between or near the strands 304 such that the cooling fluid passing therethrough can remove heat from the strands 304 in proximity to the strands 304.

[0040] In FIG. 3A, the arrow indicates one possible flow direction through the winding 110. Of course, in one embodiment, the direction of flow can be reversed. The headers disclosed below provide fluid to enter and exit the winding 110. More specifically, the fluid can flow into the passage 304, cross the strands 305, remove the heat therein, and then exit the winding 110. The coolant can enter as a liquid and, as it crosses the winding 110, remove heat from the winding 110 and may vaporize (entirely or partially). Thus, the flow exiting the winding can be any of a gas, a liquid, or a combination thereof.

[0041] Referring now to FIG. 3C, the separator 350 includes a separator body 352. The separator body 352 can be formed as a solid piece of material or can include a hollow region 354 as shown in FIG. 3C. In one embodiment, the separator 350 / separator body 352 can be formed of a non-conductive material. In one embodiment, the separator 350 is formed of a ceramic material.

[0042] Enclosed within the separator body 352 is a coolant passage 356. The coolant passage 356 can be formed as a tube that is a separate element or can be formed as a tube formed by the separator body 352.

[0043] In FIG. 3C, the arrow indicates one possible flow direction through the separator 350. Of course, in one embodiment, the direction of flow can be reversed. The headers disclosed below provide the fluid entering and leaving the separator. More specifically, the fluid can enter the passage 356, cross the separator body 352, remove the heat therein, and then exit the separator 350. In one embodiment, the separator is disposed adjacent to the winding 110 and can remove heat from the outside thereof. Similar to the above, the coolant enters as a liquid (or a mixture of liquid and gas) and vaporizes (entirely or partially) while removing heat from the separator as it crosses the separator. Thus, the flow exiting the separator 350 can be any of gas, liquid, or a combination thereof.

[0044] Optionally, as shown by the dashed lines, the separator 350 can be formed by a plurality of parts including a body 360 and an end U-turn 362.

[0045] FIG. 4 shows an example of a header 400 according to one embodiment. The header 400 is fluidly coupled to the stator winding 110 / separator 350, supplies cooling fluid to the winding / separator, and receives cooling fluid from the winding / separator. For simplicity, FIG. 4 shows only a single pair of winding 110 and single separator 350 (shown schematically as a pair), but those skilled in the art will understand that the header 400 can be connected to any number of windings / separators. Further, the fluid flow is described below in a system that includes both a winding and a separator that receive the fluid, although only one of them may include a flow path and the other may not receive the fluid. Further, note that the separator 350 can be omitted in an embodiment.

[0046] The header 400 includes an inlet 402 and an outlet 404. Cooling fluid enters through the inlet 402, is directed through one or both of the winding 110 and the separator 350, and exits the header 400 via the outlet 404. As shown, the header inlet 402 is above the outlet 404 with respect to gravity (arrow g). This configuration is not essential, but it improves the flow, specifically, the flow becomes uniform. The coolant flows into or out of the header 400 in the axial direction X from the inlet 402 and the outlet 404 of the header 400.

[0047] In one embodiment, the header 400 can be configured such that the cooling fluid enters the winding 110 and the separator 350 simultaneously. In such an embodiment, the fluid crosses the winding 110 / separator 350 and returns to the header 400 and is directed toward the outlet 404.

[0048] In another embodiment, the cooling fluid first enters the winding 110, crosses the winding 110, and then is directed to the separator 350. In such an embodiment, the fluid then returns to the header 400 and is directed toward the outlet 404.

[0049] Regardless of how the flow is provided to the winding / separator, the header can be separated into two plenums to prevent the incoming "cold" fluid from mixing with the "heated" fluid after passing through the winding / separator. Referring now to FIG. 5, an example of a header 500 can include an inlet plenum 502 and an outlet plenum 504. It should be understood that the description of the header 500 herein applies optionally to any embodiment of the header disclosed herein.

[0050] In FIG. 5, the inlet plenum 502 can optionally surround the outlet plenum. The inlet plenum 502 is fluidly connected to an inlet 506, and the outlet plenum 504 is fluidly connected to an outlet 508. However, in this or any other embodiment, the inlet 506 is not fluidly connected to the outlet 508 within the body 520 of the header. This ensures that the fluid entering the inlet 506 must enter the winding 110 or separator 350 in order to move from the inlet 506 to the outlet 508.

[0051] More specifically, referring also to FIG. 6, the header 500 includes a front face 554 and a back face 556. The back face 556 can include a plurality of outlet passages 550 formed on the back face 556 of the header 500. The outlet passages 550 are in fluid communication with the inlet plenum 502 such that the fluid entering the main inlet 506 can exit from the inlet plenum 502 and the header 502. The header 500 also includes a plurality of inlet passages 552 formed on the back face 556 of the header 500. Since the inlet passages are in fluid communication with the outlet plenum 504, the fluid exiting through the outlet passages 550 and passing through a part of the motor (e.g., winding / separator) can enter the outlet plenum 504.

[0052] The header 500 of FIG. 5 includes optional features related to the cross-sections of the inlet plenum 502 and the outlet plenum 504. Specifically, the inlet plenum 502 may have a cross-sectional area that varies in the g direction from the upper portion 510 of the header 500 as compared to the bottom portion 512 of the header 500. Specifically, the cross-sectional area is larger at the upper portion 510 than at the bottom portion 512. Similarly, the cross-sectional area of the outlet plenum 504 may have a cross-sectional area that increases in the x direction from the upper portion 510 of the header as compared to the bottom portion 510 of the header. The change in cross-section can create a more uniform distribution of fluid to the windings / separators. Specifically, a larger cross-sectional area is required to allow for the maximum fluid flow into the inlet plenum 502. This allows fluid to be provided to each winding / separator connected to the header. However, near the bottom portion 512 of the header 500, the number of windings / separators that need to receive fluid is relatively small. Therefore, the area required to accommodate the flow is small. The opposite is true for the outlet plenum 504. Specifically, at the upper portion of the header 500, only a few windings / separators "return" fluid to the outlet plenum 504, but at the bottom portion 512 of the header, it is desirable to increase the cross-sectional area of the outlet plenum 504 to accommodate the fluid returned from most or all of the windings / separators.

[0053] Newly, referring to FIGS. 6A, 6B, and 6C, cross-sections taken along the radius of the header 500 at the positions indicated by the arrows A, B, and C in FIG. 5, respectively, are shown. In FIG. 6A, the cross-sectional area of the inlet plenum 502 is larger than the cross-sectional area of the outlet plenum 504. For context, the flow of fluid through the winding 110 (or separator 350) is shown in FIG. 6A by an arrow indicating that the fluid exits the inlet plenum 502 through the outlet passage 550, crosses the winding 110 / separator 350, and enters the outlet plenum 504 through the inlet passage 552.

[0054] In FIG. 6B, the cross-sectional area of the inlet plenum 502 is approximately the same as the cross-sectional area of the outlet plenum 504. In FIG. 6C, the cross-sectional area of the inlet plenum 502 is smaller than the cross-sectional area of the outlet plenum 504.

[0055] In any of the embodiments disclosed herein, an orifice plate can be added to the header to promote a uniform flow distribution in the many channels connecting to the windings / separators. An example of such a plate 700 is shown in FIG. 7A, which is disposed in the inlet header 502 as shown in FIG. 7B.

[0056] One or more holes 702 can be formed in the plate 700. The plate 700 can be disposed or formed in the header 500 (or any other header disclosed herein) so as to divide one or both of the plenums into two parts. As shown in FIG. 7B, the plate 700 can divide the inlet plenum 502 into a plenum inlet side 710 and a plenum outlet side. The illustrated plate 700 has holes 702 of a constant size. However, the size of the holes can vary circumferentially. That is, in the context of FIG. 5, the size of the holes can vary from the top 510 to the bottom 512 of the header in which the plate 700 is disposed.

[0057] Liquid enters the inlet plenum 502 on the inlet side 710 and travels through the holes 702 (s) of the orifice plate 700. In certain embodiments, the liquid exits the holes 702 as a two-phase mixture on the plenum outlet side 712. The two-phase mixture then proceeds to a passage used to cool the windings. The passage can include, but is not limited to, the passage 304 (FIG. 3A) inside the winding 110 or the passage 356 (FIG. 3B) of the separator 352. Of course, the mixture can also pass through passages formed in other parts of the stator, such as the stator teeth 108 (FIG. 2).

[0058] In the above description, it has been described that the headers 400 / 500 have plenums on substantially the same plane. In another embodiment, as shown in FIG. 8, the header 800 can be formed to include two separate plenums. The two plenums are referred to as an inlet plenum element 802 and an outlet plenum element 804. In FIG. 8, the inlet plenum element 802 is closer to the stator 102 than the outlet plenum portion 804, but the order / relative position may be reversed. Similar to the above description, the coolant entering the inlet plenum element 802 is supplied to pairs of windings / separators (generally shown in boxes 110, 350) by passages 304, 356 respectively. In one embodiment, the fluid passes through the windings / separators and is returned to the outlet plenum element 804 through passages 304, 356. The inlet plenum element 802 may include the plate 700 described above.

[0059] As shown, the inlet plenum element 802 and the outlet plenum element 804 are spaced apart from each other, but they may be in contact with each other.

[0060] Furthermore, it becomes apparent that depending on the position of the header 800 with respect to the stator 102 and the rotor (e.g., the magnet holding structure 146), the header 800 (or any other header) can be placed next to the motor so that the header 800 supplies coolant to the motor. Thus, it should be noted that any combination of a motor and any header disclosed herein can be referred to as a motor assembly.

[0061] In the foregoing embodiments of the headers disclosed herein, it is assumed that each winding and each separator are directly connected to individual outlets of the header respectively (e.g., each winding / separator has unique access to the inlet and outlet of the header). In the following embodiments, the back of the header may include crossover channels such that a single discharge from the inlet plenum of the header and a single inflow to the outlet plenum can cool any of a plurality of windings, pairs of windings / separators, or other combinations of windings / separators.

[0062] For example, referring to FIG. 9, any header of this specification may include a front surface 900 and a back surface 902. The back surface 902 may include a crossover section 910 that, for example, connects the coil tube 304 and the separator tube 356 together so that both can be supplied by a single discharge at the back of the inlet plenum 502. In this way, the crossover section enables a single outlet passage 550 to supply coolant to two locations (e.g., the take-up tube 304 and the separator tube 356).

[0063] In FIG. 9, the tubes are each indicated by "i" and "o" indicating "in" and "out", respectively. When applied, the tube marked 304i carries cold cooling fluid to the winding, and the tube marked 304o carries the heated coolant from the winding. The same applies to the separator / tooth tubes.

[0064] As shown, the inlet crossover tube 910i connects the inlet connections 912, 914 that can be attached to the coil tube 304i and the separator tube 356i. Coolant enters both as indicated by arrow I.

[0065] The coolant crosses the winding / separator and returns to the respective winding 304o and separator tube 356o. The return flow of the returning coolant is indicated by arrow O. Another crossover 910o connects the tubes 3040 and 356o so that the fluid from both returns to the outlet plenum 504.

[0066] As arranged, the "outer" portion of the winding is cooled simultaneously with the inner portion of the separator, forming a cross-flow cooling regime.

[0067] All of the above teachings can be applied to various combinations of windings and separators / teeth. Figure 10 shows a perspective view of the "back side" of a stator / rotor combination. The combination shown in Figure 10 is applicable to all embodiments and can be arranged in proximity to any of the headers disclosed herein so that a coolant or other cooling method (e.g., heat pipe) can be implemented.

[0068] For the sake of brevity, the combination shown in Figure 10 is referred to as motor 1000. Motor 1000 includes a stator 1002. The stator includes a stator core 1004 and one or more stator windings 1100 supported or held by the core 1004. As shown, the core 1004 is formed from individual stator segments 1004a and combined with a ring hub 1006 and a plurality of teeth 1008 extending outwardly from the ring hub 106.

[0069] Motor 1000 also includes a rotor 1400. Although not shown, it should be understood that the rotor shown in Figure 10 includes a rotor shaft that rotates about a rotation axis. Rotor 1400 holds one or more permanent magnets 1480. Motor 1000 operates as described above.

[0070] Referring further to Figure 11, as configured, the stator core 1004 includes a ring hub 1006 and a plurality of teeth 1008 extending outwardly from the ring hub 1006. Adjacent teeth 1008 form stator slots 1012 in which one or more stator windings can be arranged. That is, each slot can accommodate a single stator winding 1100 therein or can include more than two windings as shown in Figure 10 and in further examples below.

[0071] The windings 1100 can include cooling channels as described above. As shown in Figure 10, each winding 1100 is separated from each other by a separator 1150. These separators can be any separator as described herein.

[0072] As shown in the figure, there are three windings 1100 in the slot 1012. One or more flow paths can be formed within each winding. Various examples of possible flow paths for each winding are indicated by the number of dots in each winding. In practice, the windings typically contain the same number of channels, and it should be understood that FIG. 11 is presented to show multiple possibilities in a single figure. Further, in one embodiment, the windings may not include flow paths.

[0073] As shown in the figure, each winding 1100 is separated from adjacent windings by a separator 1150. Optionally, each separator 1150 may include flow paths, similar to the windings 1100. Thus, based on FIG. 11, one of ordinary skill in the art will be able to implement at least three configurations: (1) a configuration where both the separator 1150 and the windings 1100 include flow paths, (2) a configuration where only the windings include flow paths, and (3) a configuration where only the separator 1150 includes flow paths. Further, one of ordinary skill in the art will understand that the flow paths can be connected to any of the headers disclosed above to supply coolant to the flow paths.

[0074] Further, in another embodiment, the flow paths cannot be used for coolant, and instead, heat pipes can be provided within the flow paths. For example, referring now to FIG. 12, a header 1200 can be provided that is a combination of a thermal spreader 1202 and a flow header 1204. The heat pipe 1206 extends into the winding 110 and can transfer heat to the thermal spreader. The winding can be any of the windings disclosed herein.

[0075] In the foregoing embodiments, it has been shown that the flow to the header is in the axial direction X (see FIGS. 2, 4, and 5). It should be noted that other flow directions are also possible. For example, FIG. 13 shows an inlet 1306 and an outlet 1308 arranged tangentially to the header 1300. The header 1300 (other than the inlet / outlet) can be formed in the same manner as described for any of the headers in this specification.

[0076] Alternatively, as shown in FIG. 14, the inlet 1406 and the outlet can have a flow directed in a vertical direction. The header 1400 (other than the inlet / outlet) can be formed in the same manner as described for any of the headers herein.

[0077] Although the present invention has been described in detail in connection with only a limited number of embodiments, it will be readily understood that the present invention is not limited to such disclosed embodiments. Rather, the present invention can be modified to incorporate any number of variations, modifications, substitutions, or equivalent configurations that have not been heretofore described but that are consistent with the spirit and scope of the present invention. Further, although various embodiments of the present invention have been described, it is to be understood that aspects of the present invention may include only a portion of the described embodiments. Accordingly, the present invention should not be regarded as being limited by the foregoing description, but only by the appended claims.

Claims

1. A header for an electrical machine, comprising a stator core and one or more windings including coolant passages formed therein, an inlet for receiving coolant, an outlet through which the coolant exits the header, an inlet plenum fluidly connected to the inlet, an outlet plenum fluidly separated from the inlet plenum and fluidly connected to the outlet, wherein the inlet plenum and the outlet plenum each have a different, varying cross-section from the upper part of the header compared to the bottom of the header, the inlet is a main inlet, the outlet is a main outlet, and the header includes a front face and a back face, the header further includes a plurality of outlet passages formed in the back face of the header and in fluid communication with the inlet plenum so that coolant entering the main inlet can exit from the inlet plenum and the header, a plurality of inlet passages formed in the back face of the header and in fluid communication with the outlet plenum so that coolant exiting the outlet passages and passing through a part of the motor can enter the outlet plenum, including a header, wherein at least one of the plurality of outlet passages is connected to another one of the plurality of outlet passages by a first crossover section.

2. The header according to claim 1, wherein the inlet plenum and the outlet plenum are in the same plane.

3. The header according to claim 1, wherein the inlet plenum and the outlet plenum are arranged side by side and spaced apart from each other in parallel.

4. The header according to claim 1, wherein the inlet plenum includes an orifice plate disposed therein that divides the inlet plenum into a plenum inlet side and a plenum outlet side.

5. The header according to claim 4, wherein the orifice plate includes a plurality of holes.

6. The header according to claim 5, wherein the size of the holes varies from the upper part of the header to the bottom part of the header.

7. The header according to claim 5, wherein coolant is received into the inlet plenum on the plenum inlet side, enters the plenum outlet side through the holes, and exits the header through the outlet passages.

8. The header according to claim 1, wherein at least one of the plurality of inlet passages is connected to another one of the plurality of inlet passages by a second crossover section.

9. The header according to claim 1, wherein the inlet and the outlet are arranged to receive and discharge a coolant along the axial direction of the header.

10. The header according to claim 1, wherein the inlet and the outlet are arranged to receive and discharge a coolant along the tangential direction of the header.

11. The header according to claim 1, wherein the inlet and the outlet are arranged to receive and discharge a coolant along the vertical direction of the header.

12. A motor, comprising a rotor, a stator, an electrical machine header including a stator core and one or more windings having coolant passages formed therein, an inlet for receiving a coolant, an outlet through which the coolant exits the header, an inlet plenum fluidly connected to the inlet, an outlet plenum fluidly separated from the inlet plenum and fluidly connected to the outlet, the header comprising the header, wherein the inlet plenum and the outlet plenum each have a different, varying cross-section from the upper part of the header compared to the bottom of the header, the header is arranged with respect to the motor to supply the coolant received at the inlet plenum to the motor and receive the coolant returned from the motor to the outlet plenum, the inlet is a main inlet, the outlet is a main outlet, the header includes a front face and a back face, the header further comprises, a plurality of outlet passages formed in the back face of the header and in fluid communication with the inlet plenum so that the coolant entering the main inlet can exit the inlet plenum and the header and supply coolant to a part of the stator, a plurality of inlet passages formed in the back face of the header and in fluid communication with the outlet plenum so that the coolant exiting the outlet passages and passing through the part of the stator can enter the outlet plenum, comprising, a motor, wherein at least one of the plurality of outlet passages is connected to another one of the plurality of outlet passages by a first crossover section.

13. The motor according to claim 12, wherein the part of the stator is a stator winding.

14. The motor according to claim 12, wherein the part of the stator is a winding separator.

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