Cooling systems for e-machines having a winding arrangement

Abstract

An e-machine comprising a stator core having a radially outer surface, a first axial end and a second axial end and a slot that extends between the first axial end and the second axial end, where a plurality of winding members are received in the slot and that extend between the first axial end and the second axial end, the stator core also including a cooling channel extending through the stator core in a direction parallel to the longitudinal axis, wherein the cooling channel is fluidically isolated from the slot, and wherein a first distance between the cooling channel and the radially outer surface is greater than a second distance between the cooling channel and the slot.

Description

PATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)COOLING SYSTEMS FOR E-MACHINES HAVING A WINDING ARRANGEMENTTECHNICAL FIELD

[0001] The present disclosure relates, generally, to an e-machine and, more particularly, to an e-machine system with a cooling channel disposed through a stator core thereof.BACKGROUND

[0002] E-machines, such as electric motors, electric generators, and combination electric motor / generators, are provided for a variety of uses. For example, electric traction motors are used in electric vehicles, electric locomotives, and so on. Electric generators also have many industrial uses.

[0003] E-machine systems typically generate heat during operation. Additionally, e-machine systems may operate in high-temperature environments. Elevated temperatures may hinder performance and / or cause other disadvantages associated with the e-machine. Thus, it is desirable to include cooling features in the e-machine. However, the design and provision of such cooling features remains challenging. There may be detrimental increases in costs, part count, device complexity, size, bulkiness, and / or weight if such cooling features are included.

[0004] Thus, there remains a need for an e-machine system that provides effective cooling. There also remains a need for e-machine systems where the cooling features are provided in a relatively compact, low-weight arrangement. There is also a need for an e-machine system including cooling features that may be manufactured with high efficiency and with reduced costs and manufacturing time.BRIEF SUMMARY

[0005] This summary is provided to describe select concepts in a simplified form that are further described in the Detailed Description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] According to a first aspect of the invention, there is provided an e-machine comprising a stator core having a radially outer surface, a radially inner surface, a first axialPATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)end and a second axial end, the first axial end and the second axial end being separated along a longitudinal axis. The stator core includes a slot that extends between the first axial end and the second axial end and a plurality of winding members, the plurality of winding members including a plurality of segments that are received in the slot and that extend between the first axial end and the second axial end of the stator core. The stator core also includes a cooling channel extending through the stator core in a direction parallel to the longitudinal axis. The cooling channel is fluidically isolated from the slot. A first distance defined between the cooling channel and the radially outer surface of the stator core is greater than a second distance defined between the cooling channel and the slot.

[0007] In an embodiment, the cooling channel has a first opening thereto, the first opening being disposed at the first axial end of the stator core, and a second opening thereto, the second opening being disposed at the second axial end of the stator core. The e-machine further comprises a fluid coolant system configured to provide a fluid coolant flow to the stator core. The e-machine further comprises an e-machine housing comprising a fluid inlet and a fluid outlet spaced apart with respect to the longitudinal axis. The fluid inlet is fluidically connected to the first opening of the cooling channel. The fluid outlet is fluidically connected to the second opening of the cooling channel. The fluid inlet and the fluid outlet are arranged with respect to the cooling channel such that fluid coolant is configured to be received from the fluid coolant system to the fluid inlet, to flow from the fluid inlet to the first opening of the cooling channel, to flow through the cooling channel, and to flow out of the second opening of the cooling channel to the fluid outlet. The fluid inlet and the fluid outlet are arranged with respect to the cooling channel to reduce abrupt changes in the direction of fluid coolant flow to thereby promote laminar flow of fluid coolant through the cooling channel.

[0008] In an alternative embodiment, the cooling channel has a first opening disposed at a first intermediate location between the first axial end and the second axial end of the stator core and a second opening disposed at a second intermediate location between the first axial end and the second axial end of the stator core.

[0009] In an embodiment combinable with the above embodiments, a cross-section of the cooling channel has a circumferential extension extending along an arc of a circumference of an imaginary circle defined about the longitudinal axis and has a radial extension extending in a direction perpendicular to the longitudinal axis.PATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)

[0010] In an embodiment, the circumferential extension is approximately six times greater than the radial extension.

[0011] In an embodiment combinable with the above embodiments, interior surfaces of the cooling channel are curved and do not comprise any vertices.

[0012] In an embodiment combinable with the above embodiments, a center point of the cooling channel is offset from a center point of the slot in a direction perpendicular to the longitudinal axis.

[0013] In an embodiment combinable with the above embodiments, the plurality of winding members comprise first and second end winding members, the first end winding member located proximate to the fluid inlet and the second end winding member located proximate to the fluid outlet, and wherein the e-machine further comprises a first deflector member disposed between the fluid inlet and the first end winding member and a second deflector member disposed between the second end winding member and the fluid outlet.

[0014] In an embodiment combinable with the above embodiments, the first and second deflector members are configured to prevent fluid coolant from flowing to the first and second end winding members, respectively.

[0015] In an embodiment combinable with the above embodiments, the first and second deflector members each comprise a plurality of holes defined therethrough, the first and second deflector members being configured to allow fluid coolant to be sprayed, via the plurality of holes, onto the first and second end winding members, respectively.

[0016] In an embodiment combinable with the above embodiments, the stator core of comprises a plurality of slots and a plurality of cooling channels. The number of slots and the number of cooling channels may be equal.

[0017] In an embodiment combinable with the above embodiments, the e-machine is an electric motor.

[0018] In an embodiment combinable with the above embodiments, the e-machine is an electric generator.

[0019] Also disclosed herein is a vehicle including an e-machine in accordance with the above-described aspects and embodiments.

[0020] Other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the preceding background.PATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)BRIEF DESCRIPTION OF DRAWINGS

[0021] The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:

[0022] FIG. 1 is a schematic illustration of an e-machine system;

[0023] FIG. 2 is a cross-sectional view of an e-machine in accordance with embodiments of the invention;

[0024] FIG. 3 is a cross-sectional view of an e-machine in accordance with embodiments of the invention;

[0025] FIG. 4 is an isometric view of the e-machine shown in FIG. 3;

[0026] FIG. 5 is a schematic diagram of the cross-section of a cooling channel in accordance with embodiments of the invention;

[0027] FIG. 6 is a representation of different shapes of cooling channels;

[0028] FIG. 7 is a cross-sectional view of an e-machine in accordance with embodiments of the invention;

[0029] FIG. 8 is a cross-sectional view of an alternative e-machine in accordance with embodiments of the invention; and

[0030] FIG. 9 is an view of the e-machine shown in FIG. 8.DETAILED DESCRIPTION

[0031] The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Thus, any embodiment described herein as “exemplary” is not necessarily to be constmed as preferred or advantageous over other embodiments. All of the embodiments described herein are exemplary embodiments provided to enable persons skilled in the art to make or use the present disclosure and not to limit the scope of the present disclosure, which is defined by the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description.

[0032] Broadly, example embodiments disclosed herein include an e-machine system, such as an electric motor system, having features that provide effective cooling for efficient high-temperature operation of the e-machine.PATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)

[0033] The stator member of the e-machine includes a stator core with a radially outer surface, a radially inner surface, and a plurality of slots (i.e., grooves, passages, etc.) that extend between a first axial end and a second axial end of the stator core. The slots may extend along a respective longitudinal axis that is parallel to centered upon an axis of rotation of the rotating group of the e-machine. The slots may be circumferentially arranged (e.g., spaced equally) about the axis of rotation. In various embodiments, the slots may be open to the radially inner surface of the stator core.

[0034] The stator core includes a plurality of winding members comprising a plurality of longitudinal segments that are received in respective slots. In at least one of the slots, there may be a group of longitudinal segments. These longitudinal segments have a cross-sectional shape (taken through the longitudinal axis of the slot). These longitudinal segments are disposed (i.e., layered, oriented, etc.) in an abutting arrangement.

[0035] The e-machine may also include a fluid coolant system that may provide a cooling fluid (refrigerant, coolant, oil, air, other gas, other liquid, etc.) to the e-machine, which preferably also does not have corrosive effects on the e-machine. In embodiments, the fluid coolant system provides pressurized cooling fluid to the e-machine.

[0036] E-machines as disclosed herein may be relatively compact and lightweight. The e-machine may also provide manufacturing benefits, such as a relatively low part count, as well as ease of assembly, installation, repair, and replacement.

[0037] FIG. 1 is a schematic view of an e-machine system 100 according to example embodiments of the present disclosure. The e-machine system 100 may have a variety of configurations. In some embodiments, the e-machine system 100 may be configured as a traction drive system 102 that is included, for example, on a vehicle 106. Thus, the traction drive system 102 may be configured for driving one or more wheels 104 of the vehicle 106. More specifically, the wheels 104 may be included at opposite ends of an axle 111, and a chassis 107 may be supported on the wheels 104 by a suspension system (not shown). The vehicle 106 may be an electric car, truck, van, motorcycle, boat, or other vehicle. However, it will be appreciated that the e-machine system 100 may be configured otherwise without departing from the scope of the present disclosure, such as in the form of an electric generator that is not included on a vehicle.

[0038] Generally, the e-machine system 100 may include a housing 125. The housing 125 may include an e-machine housing 124 with a cavity 129 defined therein. The e-machinePATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)system 100 may also include an e-machine 110 that is received within the cavity 129 and that is partially or wholly housed within the e-machine housing 124.

[0039] The e-machine 110 may be an electric motor 112. For example, in some embodiments, the electric motor 112 may be an AC three-phase electric motor. However, it will be appreciated that the e-machine 110 may be configured otherwise. The e-machine 110 may alternatively be configured as an electric generator. Furthermore, the e-machine 110 may be operable in some modes as a motor and in additional modes as a generator. The e-machine 110 includes a rotor member 118 and a stator member 119 that are housed within the cavity 129 of the e-machine housing 124.

[0040] The rotor member 118 may be supported on a shaft 116, and the shaft 116 is supported for rotation about a longitudinal axis 109 within the e-machine housing 124. The stator member 119 of the e-machine 110 may be fixed within the e-machine housing 124 and at least partly surrounds the rotor member 118 and the shaft 116. In embodiments in which the e-machine 110 is an electric motor 112, the shaft 116 may be referred to as an output shaft 116 of the electric motor 112. In some embodiments, such as when the e-machine system 100 is mounted on a vehicle 106, a gear connection member 128 (e.g., a gear, a spline on the shaft 116, or other part with gear teeth features) may be operably supported on the shaft 116.

[0041] In various embodiments, the e-machine system 100 includes a transmission 130. The transmission 130 may include a geartrain 132 that is housed within a gearbox housing 136 of the housing 125. The gearbox housing 136 may be attached (e.g., fixed) to a side wall 127 of the e-machine housing 124.

[0042] The geartrain 132 may operatively connect the e-machine 110 and the axle 111 and may transmit power therebetween. The e-machine 110 may be coupled to the wheels 104 via the transmission 130. The geartrain 132 may be attached to the gear connection member 128 and to the axle 111. The gearbox housing 136 and the e-machine housing 124 may be moveably supported on the axle 111 by one or more bearings 114 (e.g., a bearing sleeve, suspension tube, etc.) such that the axle 111 may rotate relative thereto.

[0043] During operation, the electric motor 112 may rotatably drive the shaft 116 and the gear connection member 128 supported thereon. This rotational power may transfer to the geartrain 132, which may transmit the power to the axle 111 to rotate the wheels 104 and propel the vehicle 106. These operations may be controlled by a control system 133. ThePATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)control system 133 may control speed of the motor 112 and / or other functions of the motor 112.

[0044] Furthermore, the e-machine system 100 may include a fluid coolant system 140. The fluid coolant system 140 may be configured for circulating a fluid, such as a fluid coolant. The fluid coolant may be oil, for example. In embodiments, the fluid coolant system 140 is configured to supply pressurized fluid coolant, and may comprise a pump or other such means for delivering pressurized fluid coolant.

[0045] The fluid coolant system 140 is coupled to the stator member 119. Accordingly, the fluid coolant system 140 is configured to provide cooling to the stator member 119. This, in turn, provides a degree of cooling to the rotor member 118, to bearings, and / or to other adjacent areas of the e-machine 110.

[0046] As represented in FIG. 2, which shows a cross-sectional view of one half of the e-machine 100, with the longitudinal axis 109 of the e-machine shown at the bottom of the figure, the e-machine housing 124 may be cylindrical and hollow. The e-machine housing 124 may include an outer radial wall 150, a first axial wall 151 and a second axial wall 152. The outer radial wall 150 may extend in a circumferential direction about the longitudinal axis 109 and may extend longitudinally between the first axial wall 151 and the second axial wall 152. The first axial wall 151 and second axial wall 152 may be disc-shaped and may extend transverse to the longitudinal axis 109. In some embodiments, the outer radial wall 150 and first axial wall 151 may be integrally connected so as to be one-piece and unitary, whereas the second axial wall 152 may be removably attached to the other end of the outer radial wall 150. The outer radial wall 150, first axial wall 151, and second axial wall 152 may collectively define a cavity therein. In embodiments, the cavity is substantially cylindrical and may be centered on the longitudinal axis 109.

[0047] The stator member 119 includes a stator core 154. The stator core 154 is typically hollow and cylindrical so as to include a radially outer surface 156, an radially inner surface 158, a first axial end 160, and a second axial end 162. In various embodiments, the stator core 154 comprises a plurality of disc-shaped laminations that are bonded together in a stacked configuration and are arranged along the axis 109 so as to collectively define the outer radial surface 156 and the inner radial surface 158. It will be appreciated that different widths of the disc-shaped laminations are possible, and that the widths of the disc-shaped laminations may be chosen based, for example, on manufacturing considerations.PATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)

[0048] As shown in FIG. 2, the stator core 154 includes at least one, and preferably a plurality of, slot(s) 164 (i.e., grooves, passages, etc.). It will be appreciated that the laminations of the stator core 154 may individually include notches that, when stacked together, collectively define the slots 164. The slots may have various cross-sections, for example curved or rectangular cross-sections. In some embodiments, the slots 164 may be open at the inner radial surface 158. Alternatively, the slots 164 may be closed at the inner radial surface 158. Each slot 164 extends parallel to the longitudinal axis 109 between the first axial end 160 and the second axial end 162 of the stator core 154. The slots 164 may be open at the first axial end 160 and the second axial end 162 of the stator core 154. The plurality of slots 164 may be disposed in a spaced arrangement (e.g., be equally spaced) about the longitudinal axis 109.

[0049] The stator member 119 may further include a plurality of windings (i.e., winding members, wiring members, etc.). The windings are electrically conductive and typically comprise a plurality of elongate segments. The windings are arranged in a plurality of coils that wrap back-and-forth between first and second axial ends 160, 162 of the stator core 154 and between different ones of the plurality of slots 164.

[0050] Accordingly, the windings include a plurality of longitudinal segments that are received in the slots 164 of the stator core 154 and that extend generally along the axis of the respective slot 164.

[0051] The windings also include a plurality of first end windings 188 proximate to the first axial end 160 of the stator core 154 and a plurality of second end windings 189 proximate to the second axial end 162. The first end windings 188 connect respective pairs of longitudinal segments in different slots 164, and the first end windings 188 may be disposed outside of the stator core 154 on the first axial end 160. In some embodiments, at least one of the first end windings 188 may extend away from the first axial end 160 to electrically connect to the control system 133. Furthermore, the second end windings 189 connect respective pairs of the longitudinal segments in different slots 164. The second end windings 189 may be disposed outside the stator core 154 at the second axial end 162. The first and second end windings 188, 189 electrically connect ones of the longitudinal segments 172 for operation of the stator member 119. In some embodiments, at least one of the second end windings 189 may extend away from the second axial end 162 to electrically connect to the control system 133.PATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)

[0052] As is known, as current is passed through the plurality of windings, heat is generated in the windings due to resistive heating. It is desirable to improve upon conventional approaches for cooling the windings of the stator core, such as cooling water jackets, whilst also reducing the mass of the stator core.

[0053] In accordance with embodiments of the invention, in order to provide cooling to the windings, one or more cooling channels 181 are formed directly in the stator core 154. Whilst it will be appreciated that the stator core 154 may include a plurality of cooling channels 181, the below description will be provided with respect to a single cooling channel 181. The cooling channel 181 is fluidically isolated from the slot 164 formed in the stator core. The cooling channel 181 has a first opening 182 and a second opening 183. The cooling channel 181 extends through the stator core 154. In the embodiment shown in FIG. 2, the one or more cooling channels 181 extend entirely through the stator core 154, with the first opening 182 of the one or more cooling channels 181 being disposed at the first axial end 160 of the stator core 154, and the second opening 183 being disposed at the second axial end 162 of the stator core 154.

[0054] During operation, fluid coolant may be received at the first opening 182 of the cooling channel 181 from a fluid inlet 142 connected to the fluid coolant system, flow through the cooling channel 181 to remove heat from the windings of the e-machine, flow out of the second opening 183 of the cooling channel 181 and then exit from the e-machine at a fluid outlet 144.

[0055] In order to provide cooling to the end windings 188, 189, fluid coolant may be sprayed onto the end windings 188, 189 of the stator via holes / spray jets formed in deflectors 500, 550 that are positioned between the fluid inlet 142 and the first end winding 188 and between the fluid outlet 144 and the second end winding 189. In operation, fluid coolant is introduced via the fluid inlet 142 to the area between the stator housing and the deflectors 500, 550. Some of this fluid coolant is sprayed onto the first end winding 188 via holes formed in the deflector 500. The remaining fluid coolant flows through the cooling channel 181 formed in the stator core 154. A portion of the fluid coolant flowing to the fluid outlet 144 is also sprayed onto the second end winding 189 via holes formed in the deflector 550.

[0056] It will be appreciated that the deflectors 500, 550 may alternatively not include holes / spray jets for providing spray cooling to the end windings 188, 189. Turning to FIG. 3, another embodiment of an e-machine is shown in which the deflectors 500, 550 do notPATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)include holes / spray jets. As can be seen in FIG. 3, the stator core 154 includes a slot 164 within which longitudinal segments 172 of windings are disposed. The longitudinal segments 172 of the windings are connected to each other at the first and second ends 160, 162 of the stator core 154 via first and second end windings 188, 189. The stator core 154 includes a cooling channel 181 that extends therethrough in a direction which is parallel to the longitudinal axis 109. The cooling channel 181 includes a first opening 182 which is disposed at the first axial end 160 of the stator core 154 and a second opening 183 which is disposed at the second axial end 162 of the stator core 154.

[0057] During operation, fluid coolant may be received at fluid inlet 142. The fluid coolant flows from the fluid inlet 142 to the first opening 182 of the cooling channel 181, then flows through the cooling channel 181 so as to remove heat from the longitudinal segments 172. The fluid coolant then exits the cooling channel 181 via the second opening 183 and then flows to the fluid outlet 144. In embodiments, the deflector members 500, 550 fluidically isolate the end windings 188, 189 from the fluid inlet 142 and the fluid outlet 144 or allow for spraying of the end windings 188, 189 with a portion of the fluid coolant.

[0058] As can be seen in FIG. 3, the cooling channel 181 is disposed closer to the radially outer surface 156 of the stator core 154 as compared to the slot 164. In order words, a first distance di between a radially outer extent of the cooling channel 181 and the radially outer surface 156 is less than a second distance d2 between a radially outer extent of the cooling channel 181 and a radially outer section of the slot 164. It will also be appreciated that a first distance di between a center point of the cooling channel 181, when the cooling channel is viewed in cross-section, and the radially outer surface 156 is less than a second distance between a center point of the cooling channel 181, when the cooling channel is viewed in cross-section, and a radially outer section of the slot 164.

[0059] It has been recognized by the present inventors that when the cooling channel 181 is located closer to the slot 164 than the radially outer surface 156 of the stator core 154, for example close to the “teeth” of the stator core, fluid coolant flowing through the cooling channel 181 gives rise to electromagnetic interference issues that reduce e-machine efficiency. By positioning the cooling channel 181 closer to the radially outer surface 156 of the stator core 154 than to the slot 164, improved cooling of the segments 172 may be achieved without reducing the e-machine efficiency.

[0060] As can also be seen in FIG. 2 and FIG. 3, the manner in which the fluid inlet 142 is fluidically connected to the first opening 182 of the cooling channel 181 and in which thePATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)fluid outlet 144 is fluidically connected to the second opening 183 of the cooling channel 181, eliminates abrupt changes in direction of fluid coolant flow from the fluid inlet 142, through the cooling channel 181 to the fluid outlet 144. Through the use of computational fluid dynamics models, such as investigations using finite element analysis software packages, it has been recognized by the present inventors that laminar flow of fluid coolant through the cooling channel improves the cooling effect of the fluid coolant. The arrangement of the fluid inlet 142 and the fluid outlet 144 with respect to the cooling channel 181, in which abrupt changes in direction are minimized or eliminated, promotes laminar flow of the fluid coolant through the cooling channel 181 and reduces turbulent flow, thereby improving the cooling effect of the fluid coolant.

[0061] FIG. 4 shows an isometric view of first openings 182 of cooling channels 181 in the stator core 154. As can be seen from FIG. 4, the first openings 182 and the cooling channels 181 may be circumferentially arranged (e.g., spaced equally) about the longitudinal axis (not shown in this figure). As can also be seen in FIG. 4, a radial seal 250 may be included, where the radial seal 250 abuts against the deflector 500 so as to prevent radial ingress of fluid coolant. In the embodiment shown in FIG. 4, the radial seal 250 comprises an O-ring. In alternative embodiments, the radial seal 250 comprises another type of seal, for example a resilient engagement section or other such structure of the deflector 500, which resilient engagement section is pre-loaded so as to resiliently flex against a surface of the e-machine so as to radially seal against the ingress of fluid coolant. An axial seal 260 may also be included, where the axial seal abuts against the deflector 500 so as to prevent axial ingress of fluid coolant. In the embodiment shown in FIG. 4, the axial seal 260 comprises an O-ring. In alternative embodiments, the axial seal 260 comprises another type of seal, for example a resilient engagement section or other such structure of the deflector 500, which resilient engagement section is pre-loaded so as to resiliently flex against a surface of the e-machine so as to axially seal against the ingress of fluid coolant.

[0062] FIG. 5 shows a schematic of a cooling channel 181. As can be seen in FIG. 4 and FIG. 5, the cooling channel has a cross-section, the cross-section having a circumferential extension extending along an arc 180 of a circumference of an imaginary circle defined about the longitudinal axis and a radial extension extending in a direction perpendicular to the longitudinal axis. It has been found by the present inventors that this shape of cooling channel improves the cooling effectiveness of the fluid coolant being passed through the cooling channel 181. Furthermore, the circumferential extension is preferably approximately sixPATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)times greater than the radial extension. In particular, multiple different cross-sections of cooling channels were investigated, with the cross-sectional shape shown in FIGs 4 and 5 being found as the most effective in both cooling the windings and in reducing the mass of the stator core 154.

[0063] FIG. 6 shows some of these different cross-sections of cooling channel. In this figure, type 1 corresponded to a stator core with circular cooling channels, Type 2 corresponded to a stator core with cooling channels having a circumferential extension that is approximately 2.7 times greater than the radial extension, Type 3 corresponded to a stator core having cooling channels with a circumferential extension that is approximately six times greater than the radial extension, and Type 4 corresponded to a stator core with cooling channels having a radial extension that is approximately twice as large as the circumferential extension.

[0064] Table 1 shows the results of cooling tests using these different cross-sectional shapes of cooling channels, performed at a voltage line of 407 Volts and a current of 380 Amps:Table 1

[0065] As can be seen from Table 1, the Type 3 cross-sectional shape reduced the stator mass by the largest amount, whilst also resulting in the smallest amount of magnetic field loss and whilst also maintaining similar levels of overall efficiency and AC losses as the other types of cross-sectional shapes.

[0066] Referring back to FIG. 4 and FIG. 5, it can be seen that the interior surfaces of the cooling channel 181 are curved / rounded, such that no sharp corners or vertices are present within the interior of the cooling channel 181. This further promotes laminar flow of fluid coolant through the cooling channel 181 so as to reduce turbulence therein.

[0067] FIG. 7 shows a cross-section of a stator core 154 in accordance with embodiments of the invention. As can be seen in FIG. 7, longitudinal segments 172 of windings are disposed within slots 164 formed in the stator core 154, where the slots 164 are circumferentially arranged (equally spaced) about the longitudinal axis 109 of the stator core 154. Additionally, cooling channels 181 are formed in the stator core 154, which cooling channels 181 arePATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)fluidically isolated from the slots 164. The cooling channels 181 are each disposed at locations which are closer to a radially outer surface 156 of the stator core than to the slots 164, measured in a radial direction with respect to the longitudinal axis 109.

[0068] As can be seen in FIG. 7, a center point 190 of each cooling channel may be aligned along a line extending perpendicular to the longitudinal axis 109, with a midpoint between center points 195 of respective adjacent slots 164. The center points 190 of each cooling channel may each be offset from a respective slot 164 by a predetermined angle, such that the cooling channels are uniformly spaced about the longitudinal axis. Such an arrangement has been found to be desirable in terms of both manufacturing ease and cooling efficiency. As can also be seen in FIG. 7, there may be an equal number of cooling channels 181 and slots 164 formed in the stator core 154.

[0069] Whilst FIG. 7 shows the center points 190 of each cooling channel being uniformly spaced about the longitudinal axis 109, it will be appreciated that other distributions of cooling channels are possible. For example, the cooling channels may be non-uniformly spaced about the longitudinal axis, with the spacing between the cooling channels varying in different locations of the stator core 154.

[0070] FIG. 8 shows another embodiment of the present invention. In the embodiment of FIG. 8, a first opening 1182 of the cooling channel 1181 is not disposed at the first axial end 1160 of the stator core 1154, and is instead located at a first intermediate location between the first axial end 1160 of the stator core 1154 and the second axial end 1162 of the stator core 1154. Similarly, a second opening 1183 of the cooling channel 1181 is not disposed at the second axial end 1162 of the stator core 1154, and is instead located at a second intermediate location between the first axial end 1160 of the stator core 1154 and the second axial end 1162 of the stator core 1154.

[0071] Incorporating the first and second openings 1182, 1183 of the cooling channel 1181 at first and second intermediate locations between the first and second axial ends 1162, 1164 of the stator core 1154 may be achieved via a variation in the laminations forming the stator core 1154. For example, laminations of a reduced diameter may be utilized in the first and second intermediate locations so as to allow fluid to enter into the fluid channel from a direction perpendicular to the longitudinal axis 109.

[0072] As will be appreciated, when fluid coolant is supplied to the cooling channel 1181 from a direction that is perpendicular to the longitudinal axis 109, the amount of turbulence in the flow of fluid coolant through the cooling channel 1181 will increase as compared toPATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)previously-described embodiments. However, configurations where the perpendicular supply of fluid coolant may be useful when there are space constraints that prevent a supply of fluid coolant to the cooling channel 1181 from a direction that is substantially parallel to the longitudinal axis 109.

[0073] FIG. 9 shows an isometric view of the stator core shown in FIG. 8. As can be seen from FIG. 9, the first opening 1182 of the cooling channel 1181 is set back from the first axial end 1160 of the stator core 1154.

[0074] In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as “first,” “second,” “third,” etc. simply denote different singles of a plurality and do not imply any order or sequence unless specifically defined by the claim language. The sequence of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order according to such sequence unless it is specifically defined by the language of the claim. The process steps may be interchanged in any order without departing from the scope of the present disclosure as long as such an interchange does not contradict the claim language and is not logically nonsensical.

[0075] Furthermore, depending on the context, words such as “connect” or “coupled to” used in describing a relationship between different elements do not imply that a direct physical connection must be made between these elements. For example, two elements may be connected to each other physically, electronically, logically, or in any other manner, through one or more additional elements.

[0076] As used herein, the term “axial” refers to a direction that is generally parallel to or coincident with an axis of rotation, axis of symmetry, or centerline of a component or components. For example, in a cylinder or disc with a centerline and generally circular ends or opposing faces, the “axial” direction may refer to the direction that generally extends in parallel to the centerline between the opposite ends or faces. In certain instances, the term “axial” may be utilized with respect to components that are not cylindrical (or otherwise radially symmetric). For example, the “axial” direction for a rectangular housing containing a rotating shaft may be viewed as a direction that is generally parallel to or coincident with the rotational axis of the shaft. Furthermore, the term “radially” as used herein may refer to a direction or a relationship of components with respect to a line extending outward from a shared centerline, axis, or similar reference, for example in a plane of a cylinder or disc that isPATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)perpendicular to the centerline or axis. In certain instances, components may be viewed as “radially” aligned even though one or both of the components may not be cylindrical (or otherwise radially symmetric). Furthermore, the terms “axial” and “radial” (and any derivatives) may encompass directional relationships that are other than precisely aligned with (e.g., oblique to) the true axial and radial dimensions, provided the relationship is predominantly in the respective nominal axial or radial direction. As used herein, the term “substantially” denotes within 5% to account for manufacturing tolerances. Also, as used herein, the term “about” denotes within 5% to account for manufacturing tolerances.

[0077] While at least one exemplary embodiment has been presented in the foregoing detailed description of the present disclosure, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the present disclosure. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

PATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)CLAIMSWhat is claimed is:

1. An e-machine comprising:a stator core (154, 1154), the stator core having a radially outer surface (156, 1156), a radially inner surface (158), a first axial end (160, 1160) and a second axial end (162, 1162), the first axial end and the second axial end being separated along a longitudinal axis (109), the stator core having a slot (164) that extends between the first axial end and the second axial end;a plurality of winding members, the plurality of winding members comprising a plurality of segments (172) that are received in the slot and that extend between the first axial end and the second axial end; anda cooling channel (181, 1181) extending through the stator core in a direction parallel to the longitudinal axis, wherein the cooling channel is fluidically isolated from the slot, and wherein a first distance between the cooling channel and the radially outer surface is greater than a second distance between the cooling channel and the slot.

2. The e-machine of Claim 1, wherein the cooling channel has a first opening (182, 1182) disposed at the first axial end of the stator core and a second opening (183, 1183) disposed at the second axial end of the stator core, and wherein the e-machine further comprises:a fluid coolant system (140) configured to provide a fluid coolant flow, and an e-machine housing (124) comprising a fluid inlet (142) and a fluid outlet (144) spaced apart with respect to the longitudinal axis, the fluid inlet being fluidically connected to the first opening of the cooling channel and the fluid outlet being fluidically connected to the second opening of the cooling channel, wherein the fluid inlet and the fluid outlet are arranged with respect to the cooling channel such that fluid coolant is configured to be received from the fluid coolant system to the fluid inlet, to flow from the fluid inlet to the first opening of the cooling channel, to flow through the cooling channel, and to flow out of the second opening of the cooling channel to the fluid outlet, and wherein the fluid inlet and the fluid outlet are arranged with respect to the cooling channel to reduce abrupt changes in aPATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)direction of fluid coolant flow to thereby promote laminar flow of fluid coolant through the cooling channel.

3. The e-machine of Claim 1 , wherein the cooling channel has a first opening disposed at a first intermediate location between the first axial end and the second axial end of the stator core and a second opening disposed at a second intermediate location between the first axial end and the second axial end of the stator core.

4. The e-machine of any preceding claim, wherein a cross-section of the cooling channel has a circumferential extension extending along an arc (180) of a circumference of an imaginary circle defined about the longitudinal axis (109) and has a radial extension extending in a direction perpendicular to the longitudinal axis.

5. The e-machine of Claim 4, wherein the circumferential extension is approximately six times greater than the radial extension.

6. The e-machine of Claim 4 or Claim 5, wherein interior surfaces of the cooling channel are curved and do not comprise any vertices.

7. The e-machine of any preceding claim, wherein a center point (1 0) of the cooling channel is offset from a center point (195) of the slot in a direction perpendicular to the longitudinal axis.

8. The e-machine of any preceding claim, wherein the plurality of winding members comprise first and second end winding members (188, 189), the first end winding member (188) located proximate to the fluid inlet and the second end winding member located proximate to the fluid outlet, and wherein the e-machine further comprises a first deflector member (500) disposed between the fluid inlet and the first end winding member and a second deflector member (550) disposed between the second end winding member and the fluid outlet.

9. The e-machine of Claim 8, wherein the first and second deflector members are configured to prevent fluid coolant from flowing to the first and second end winding members (188, 189), respectively.

10. The e-machine of Claim 8, wherein the first and second deflector members each comprise a plurality of holes defined therethrough, the first and second deflector membersPATENT APPLICATIONAttorney Docket No. G001412 (123.1571GB)being configured to allow fluid coolant to be sprayed, via the plurality of holes, onto the first and second end winding members (188, 189), respectively.

11. The e-machine of any preceding claim, wherein the stator core comprises a plurality of slots and a plurality of cooling channels.

12. The e-machine of claim 11, wherein the number of slots and the number of cooling channels is equal.

13. The e-machine of any preceding claim, wherein the e-machine is an electric motor.

14. The e-machine of any preceding claim, wherein the e-machine is an electric generator.

15. A vehicle comprising the e-machine of any preceding claim.

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