Cooling channel in slot of motor

Abstract

The present disclosure provides an in-slot cooling channel for an electric machine. A cooling manifold (112, 800) for an electric machine (14, 100) is presented that utilizes a hollow bolt (110) feed solution that utilizes an existing bolt structure and an interface with a housing (201) of the electric machine to form a fluid passage for directing coolant to an interior portion of a stator of the electric machine (14, 100). The hollow bolt (110) forms a sealed fluid interface without the need to add additional seals, thereby reducing the manufacturing complexity of the motor (14, 100). In-slot cooling with a manifold (112, 800) or with a plurality of said manifolds can eliminate the dependence on slot liners and varnishes for limiting relative movement of end windings of the stator and providing electrical isolation while also cooling the hottest portion of the electric machine (14, 100), significantly affecting the thermal confinement capability of the electric machine.

Description

Technical Field

[0001] This specification generally relates to methods and systems for cooling electric motors in vehicles. Background Technology

[0002] During operation, the motor generates electromagnetic losses in the form of heat, which are mostly concentrated in the stator. Furthermore, the motor's sustained performance is controlled by a combination of its heat dissipation capacity and the temperature limits of its component materials. Overheating can lead to performance degradation and ultimately, motor deterioration. Summary of the Invention

[0003] The inventors have developed a system and method for at least partially solving the problem of motor overheating.

[0004] Specifically, the hottest part of the motor (e.g., the thermally limited hot spot) is the winding at the center of the stator, which may not directly receive coolant supplied by existing cooling solutions. Directly cooling the hot spot allows for higher power density and improved continuous performance compared to existing cooling solutions. In one example, direct cooling of the winding can be achieved using a cooling system for a motor having a stator and a housing, the system comprising: a cooling manifold positioned at the axial center of the stator and coaxially aligned with the central axis of the stator; and bolts clamping the stator to the housing, the bolts including a hollow section with a fluid inlet and a fluid outlet configured to deliver coolant from the hollow section to multiple passages in the cooling manifold. Coolant can flow from the housing to the cooling manifold through the hollow section and is subsequently guided to the end windings of the stator via radial passages extending into winding slots within the stator. Coolant can also circulate from the inlet of the cooling manifold to all radial passages via circumferential passages within the manifold.

[0005] In other words, multiple pathways can be incorporated into the stator, allowing coolant to flow between the stator core and windings for direct hot-spot cooling while simultaneously satisfying mechanical holding requirements. In an electric motor, counter-torque can be provided by relying on mechanical holding between the stator core and housing. Two common methods for stator holding are the use of bolts (through lugs located outside the stator yoke) and interference fits (between the stator core and housing), where bolts are not used. While interference fits are beneficial for noise, vibration, and harshness (NVH) and for forming a fluid interface with the stator core, bolts are generally preferred due to the increased core losses caused by the compressive stress of the interference fit. Therefore, while using bolts for stator holding to minimize core losses, hollow bolts provide a novel interface for introducing coolant to the center of the motor.

[0006] In this way, one or more fluid manifolds with hollow bolt feeders utilize existing bolts and interfaces with the housing to form a fluid passage to the stator windings. The hollow bolts create a sealed fluid interface without the need for additional seals, thus reducing the manufacturing complexity of the motor. Mechanical holding is also used within the slot between the stator windings and the stator core to prevent relative movement that could lead to insulation degradation. Slot liners and varnishes can be used to limit this relative movement and provide electrical isolation. Therefore, slot cooling with manifolds eliminates the need for slot liners and varnishes while still reducing relative movement and cooling the hottest spots in the machine, thereby reducing manufacturing resources and complexity while increasing the machine's thermal confinement capabilities.

[0007] The above and other advantages and features of this specification will become readily apparent when understood alone or in conjunction with the accompanying drawings, based on the following detailed description.

[0008] It should be understood that the above description of the invention is provided to present a series of concepts further described in the detailed embodiments in a simplified form. This is not intended to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims appended to the detailed embodiments. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0009] The advantages described herein will be more fully understood when read, either alone or with reference to the accompanying drawings, by reading examples of embodiments referred to herein as specific implementations, in which: Figure 1 This is a first perspective view of a portion of an exemplary motor, including hollow bolts and cooling manifolds; Figure 2 This is a cross-sectional view of an electric motor; Figure 3 It is a perspective view of the motor, showing an isometric view of the cooling manifold; Figure 4 This is a cross-sectional view of the cooling manifold in plan; Figure 5 yes Figure 4 The unfolded view of the in-plane cross-sectional view; Figure 6 This is a perspective view of the circumferential cross-section of the cooling manifold; Figure 7 This is a perspective view of the in-plane cross-section of the cooling manifold; Figure 8 A portion of an example of a stamped cooling manifold is shown; Figure 9It is a perspective view of a portion of an electric motor including a stamped cooling manifold, showing an exemplary circumferential pocket. Figure 10 This is a perspective view of the motor, showing the fluid passage; Figure 11 A portion of a motor, including the end windings of the motor stator, is shown. Figure 12 An example of an electric motor is shown, wherein a first end annular manifold is included on a first end of the stator, and a second end annular manifold is included on a second end of the stator; Figure 13 The unfolded diagram of the first end ring manifold is shown; Figure 14 An example of an electric motor is shown, in which the stator has an interference fit with the motor housing; Figure 15 It shows Figure 14 The amplification section of the motor includes the interface between the cooling manifold and multiple windings of the stator; Figure 16 An example of a motor including a circumferential channel with a cooling manifold is shown; and Figure 17 An exemplary vehicle powertrain system that may include an electric motor is schematically illustrated according to this disclosure.

[0010] Figures 1 to 16 Shown to scale, but other relative dimensions may be used if needed. Detailed Implementation

[0011] This document describes systems and methods for cooling motors in vehicles, specifically by cooling the windings at the center of the motor stator (the hottest part of the motor), which may not directly receive coolant supplied by existing cooling solutions. Motors equipped with the cooling system of this disclosure can be integrated with... Figure 17 An exemplary vehicle is schematically shown in the diagram. First, it is described... Figure 17 This provides an overview of vehicle systems, including electric motors. Then, regarding... Figures 1 to 16 Describe the cooling of the motor.

[0012] First turn Figure 17 An example of a vehicle 10 having a propulsion system 11 (e.g., an electric propulsion system) is shown. The propulsion system 11 includes an electric motor 14 (e.g., an energy conversion device). The electric motor 14 may be integrated into the axle of the vehicle 10 and may include a slot-in-slot cooling system 24 according to the present disclosure. The electric motor 14 is controlled via a controller 50. In some examples, the vehicle propulsion system 11 may also include an engine 72, wherein the engine 72 may be an internal combustion engine.

[0013] The motor 14 is further shown coupled to an energy storage device 16, which may include a battery (e.g., a traction battery), a capacitor, an inductor, or other electrical energy storage device. The motor 14 can be operated to convert mechanical energy received from the vehicle drivetrain into a form of energy suitable for storage by the energy storage device (e.g., providing generator operation). The motor 14 can also be operated to supply output (power, work, torque, speed, etc.) to the drive wheels 18 (e.g., providing motor operation). It should be understood that in some examples, the motor 14 may function as a motor only, as a generator only, or as both a motor and a generator, and as various other components for providing appropriate energy conversion between the energy storage device and the vehicle drive wheels. For example, the motor 14 may include a motor, a generator, an integrated starter generator, a starter alternator, etc., and combinations thereof. The motor 14 may also include or be coupled to an inverter 30. The inverter 30 may be configured to regulate electrical energy entering and leaving the energy storage device (e.g., a high-voltage battery). However, in other examples, the vehicle may not include an inverter.

[0014] The energy storage device 16 can be selectively connected to an external energy source 19. For example, the energy storage device 16 can be periodically connected to a charging station (e.g., a commercial or residential charging station), a portable energy storage device, etc., to allow the energy storage device 16 to be recharged.

[0015] In an example where the electric motor is a hybrid vehicle, motor 14 may be coupled to torque converter 20. Torque converter 20 is a hydraulic coupling designed to transmit rotary input from motor 14 to drivetrain 22. In the hybrid example, drivetrain 22 includes a transmission with gears and other suitable mechanical components (e.g., gearbox, axle, transfer case, etc.) designed to transmit rotational motion to drive wheels 18. Drive wheels 18 may be supported by vehicle 10 and propel the vehicle over surface 21. Torque converter 20 and motor 14 are depicted as interconnected units. However, in other examples, torque converter 20 and motor 14 may comprise separate housings.

[0016] The motor 14 may include one or more clutches designed to selectively rotatably engage the rotor of the motor 14 with the torque converter 20. For example, the one or more clutches may each include a plate, splines, and / or other suitable mechanical components that allow the motor to be rotatably engaged and disengaged from the engine 72 or the torque converter 20.

[0017] The depicted connections between the motor 14, transmission 22, and drive wheels 18 indicate the transfer of mechanical energy from one component to another, while the connection between the motor 14 and the energy storage device 16 can indicate the transfer of various forms of energy, such as electrical and mechanical. For example, torque can be transferred from the motor 14 to drive the vehicle drive wheels 18 via the transmission 22. As described above, the motor 14 can be configured to operate in generator mode and / or motor mode. In generator mode, the propulsion system 11 receives some or all of the output from the motor 14, which reduces the amount of drive output or negative torque delivered to the drive wheels 18. For example, the operation of the vehicle 10 using generator mode can achieve energy efficiency gains through regenerating negative torque, improved engine efficiency (if included), etc. Furthermore, the output received by the motor 14 can be used to charge the energy storage device 16. In motor mode, the motor 14 can supply mechanical output to the transmission 22, for example, by using electrical energy stored in a battery. Additionally, in some cases, the engine 72 can supply rotational output to the transmission 22.

[0018] The motor 14 can also be used to deliver electrical energy to external auxiliary devices during power output. The motor 14 can operate during power output when the drive wheel 18 is not moving, thereby allowing the power output from the motor 14 to be directed at least partially toward the operating auxiliary devices.

[0019] In an example where vehicle 10 includes engine 72, engine 72 may have an output terminal connected to torque converter 20 and may be integrated into the vehicle's axle. Engine 72 may be controlled via controller 50. Both engine 72 and motor 14 may serve as prime movers for driving vehicle 10. For example, vehicle 10 may be a hybrid vehicle. In the example including engine 72, rotational energy in the form of torque from engine 72, or other rotational and mechanical energy from components, may be converted into electrical energy by motor 14. The output of motor 14 to torque converter 20 may serve as an input for transmitting torque and converting torque into electrical energy during hybrid operation.

[0020] Controller 50 from Figure 17 Various sensors receive signals and employ Figure 17 The various actuators adjust vehicle operation based on received signals and instructions stored in the non-transitory memory of the controller 50. Specifically, the controller 50... Figure 17The device, shown as a conventional microcomputer, includes a microprocessor unit 52, an input / output port 54, a read-only memory 56, a random access memory 58, a keep-alive memory 59, and a conventional data bus. The controller 50 is configured to receive various signals from sensors coupled to the propulsion system 11 and to send command signals to actuators in components within the vehicle, such as the motor 14. Additionally, the controller 50 is configured to receive the pedal position (PP) of the pedal 62 actuated by the user 64. The PP can be estimated and received by a pedal position sensor 60 coupled to and from the pedal 62. Thus, in one example, the controller 50 can receive the pedal position signal and, based on the pedal position signal, adjust the actuators in the motor 14 to change the rotational output of the motor 14. Sensors communicating with the controller 50 may include motor sensors (e.g., a resolver or Hall effect sensor for sensing the rotor position of the motor), as well as wheel speed sensors 70, accelerometers, etc. The controller 50 can send commands to the pump (not shown) to control the pressure and flow rate of the coolant fluid flowing through the slot of the cooling system 24 of the motor 14.

[0021] The motor 14 may include a rotor and a stator, wherein the stator circumferentially surrounds the rotor with a gap maintained between them. Conductors (e.g., windings, copper wires) adapted to generate a magnetic field to rotate the rotor may extend through the stator. The conductors may be susceptible to overheating, at least in part due to the high electrical power. Therefore, an in-slot cooling system 24 may be employed to reduce the temperature of the conductors. For example, the in-slot cooling system 24 according to this disclosure may include a coolant fluid flowing within a slot (e.g., a through-hole) in the stator, in which the conductors are positioned. Thus, compared to a system in which the coolant only contacts the ends of the conductors not within the stator, the coolant fluid can surround the entire length of the conductors, thereby increasing the cooling effect of the coolant fluid. Specifically, the in-slot cooling system 24 may channel the coolant fluid (also referred to herein as coolant) to portions of the stator via hollow stator bolts, as referenced below. Figure 1 As described.

[0022] Now for reference Figure 1 This image shows a first perspective view of a portion of an electric motor 100, including a stator 102. The stator 102 includes a plurality of windings 104 through which current is introduced to generate a rotor located in an air gap 160 within the stator 102. Figure 1 (Not depicted in the text) magnetic field. Stator 102 can be positioned within stator core 103 of motor 100, said stator core in Figure 1 The middle is transparent. The stator core 103 is fixed to the housing of the motor 100 by multiple bolts, as shown. Figure 2 and Figure 3As shown. A set of reference axes 190 depicting the alignment of the motor 100 is shown, which is also in Figures 2 to 16 As shown in the image.

[0023] Specifically, the motor 100 includes a hollow bolt 110, which can be positioned on one side of the stator 102 and aligned parallel to the central axis of the stator 102 (e.g., ...). Figure 3 (As shown). The hollow bolt 110 can be similar to the bolts typically used to clamp the stator 102 to the housing. However, the bolt 110 can serve the dual purpose of clamping the stator 102 and providing coolant passages 113 to multiple axial locations of the stator core 103.

[0024] During operation of the motor 100, heat can accumulate in the motor 100, with the maximum heat accumulation occurring at the winding 104, which may be referred to herein as a winding hot spot. To cool the winding hot spot, coolant (such as oil, automatic transmission fluid, dielectric fluid, etc.) can be supplied to the stator 102 via the coolant passage 113 of the hollow bolt 110. Specifically, the hollow bolt 110 may include a hollow threaded bolt section 115, wherein the hollow bolt 110 is screwed into a housing. A first portion 117 of the hollow threaded bolt section 115 may extend into the housing. A second portion 119 of the hollow threaded bolt section 115 may extend into the stator core 103. The second portion 119 may include one or more radial holes 116 circumferentially positioned around the side of the hollow threaded bolt section 115. For example, four radial holes 116 may be circumferentially positioned and spaced at equal distances. The radial hole 116 allows coolant to flow from the central passage 113 of the hollow threaded bolt section 115 to the passage 118 between the stator lug hole 121 and the outer circumference 120 of the hollow bolt 110. The passage 118 formed by the hollow bolt 110 and the stator lug hole 121 is sealed to the head 130 of the bolt 110 and the housing by the clamping force of the bolt 110.

[0025] The flow of coolant through hollow bolt 110 is indicated by arrow 150. Coolant can enter hollow bolt 110 through orifice 114. Coolant can flow through a first portion 117 of hollow threaded bolt section 115 and into a second portion 119. Coolant can exit hollow threaded bolt section 115 through one or more radial holes 116 in the second portion 119 and enter passage 118. Coolant can flow along passage 118 (e.g., between the outer edge of hollow bolt 110 and the inner edge of stator lug hole 121). Coolant can flow from passage 118 through orifice 122 in cooling manifold 112 into a slot located at the axial center of stator 102. Manifold 112 can distribute coolant circumferentially around stator 102 and radially inward toward the center of stator 102 in directions generally indicated by a plurality of arrows 152. As described in more detail below, the coolant can circulate around and cool the winding 104 located at the center of the stator 102, which is different from other alternative cooling solutions that rely on circulating the coolant around the surface of the stator 102.

[0026] Figure 2 It shows Figure 1 A cross-sectional view 200 of the motor 100 shows the hollow bolt 110 and the hollow threaded bolt section 115 extending from the head 130 to the housing 201 of the motor 100. The hollow threaded bolt section 115 has a length 202, which may be shorter than the length 203 of the hollow bolt 110. The length 202 may be divided into two components: a first component length 210, corresponding to the length of a first portion 117 extending into the housing 201; and a second component length 212, corresponding to a second portion 119 of the hollow threaded bolt section 115 extending into the stator core 103. In some examples, the first component length 210 may be greater than the second component length 212. The first component length 210 may be selected such that the radial hole 116 is positioned between the lip 220 and the cooling manifold 112 positioned at the axial center of the stator core 103, allowing coolant to flow easily from within the hollow threaded bolt section 115 to the passage 118. The hollow bolt 110 may include a lip 220 surrounding the outer circumference of the hollow bolt 110, which can seal the passage 118 at the interface between the housing 201 and the stator core 103.

[0027] Hollow bolt 110 is connected to passage 204 of housing 201 via orifice 114, through which coolant can be supplied. Coolant can be supplied by a coolant pump located downstream of a coolant cooler and filter. Figure 2Not depicted. In some examples, the coolant pump may also distribute coolant to the rotor of motor 100 to cool the rotor magnets. In other examples, passage 118 may additionally or alternatively be provided by a banjo eyelet below the bolt head. Figure 1 and Figure 2 (Not depicted in the text) Supply. Additionally, it should be understood that in some examples, the motor 100 may include a plurality of hollow bolts 110, each hollow bolt 110 connected to a passage 204 supplied by a coolant pump. For example, in one example, all bolts used to clamp the stator 102 to the housing 201 may be hollow bolts 110.

[0028] Now for reference Figure 3 Perspective view 300 of motor 100 is shown, in which bolt 110 is aligned parallel to the central axis 390 of stator 102. Perspective view 300 shows an isometric view of manifold 112. Manifold 112 is composed of... Figure 1 and Figure 2 The manifold 112 is supported by bolts 302, 304, 306, and hollow bolt 110. Each of the bolts 302, 304, 306, and 110 passes through a bolt hole 308 of a corresponding bolt hole 309 in the manifold 112 to provide a rigid clamping path between the head of the bolts 302, 304, 306, and hollow bolt 110 and the housing 201, and allows the body of the manifold 112 to be made of inexpensive and readily manufactured materials, such as injection-molded plastic. The bolt hole 308 may include pin features (e.g., a lip on the hole, or a plastic feature that extends partially into the slot opening) aligning the manifold 112 with a plurality of stator slots 311 of the stator core 103. The manifold 112 can be supplied with coolant from passage 118 through a radial inlet at position 310 of the manifold 112 from a partially opened compression-restriction orifice 312, as will be described in more detail below. It should be understood that in other examples, one or more of bolts 302, 304 and 306 may be hollow bolts, such as hollow bolt 110, and coolant may be delivered to the winding 104 of stator 102 via all hollow bolts in a similar manner.

[0029] Figure 4 This is a planar cross-sectional view 400 of the cooling manifold 112, showing a first bolt hole 402 with a corresponding bolt hole 402 having a corresponding bolt hole 403; a second bolt hole 404 with a corresponding bolt hole 405; a third bolt hole 406 with a corresponding bolt hole 407; and a fourth bolt hole 408 with a compression-limiting orifice 312, wherein each of the orifices 403, 405, and 407 is Figure 3 A non-limiting example of bolt hole 308. Although Figure 4Four bolt holes / eyelets are depicted, but it should be understood that in other examples, more or fewer stator bolts may be used. In some examples, one or more of eyelets 403, 405, and 407 may be compression-limited eyelets 312 to accommodate multiple hollow bolts 110. The in-plane cross-sectional view 400 may be injection molded as a single part. Reference Figure 5 The features of cross-sectional view 400 are described in more detail.

[0030] refer to Figure 5 , Figure 4 An unfolded view 500 of the cross-sectional view 400 shows the hollow bolt 110 passing through a compression-restricting eyelet 312. The unfolded view 500 shows three circumferential sections of the manifold 112, including a first circumferential section 502, a second circumferential section 504, and a central circumferential section 506. The first circumferential section 502 and the second circumferential section 504 distribute coolant circumferentially around the stator into a plurality of winding slots 510, in which a plurality of windings 512 (e.g., winding 104) are positioned.

[0031] The central circumferential section 506 of manifold 112 includes a plurality of radial ribs 508, each radial rib 508 being a mechanical retaining feature connecting the first circumferential section 502 to the second circumferential section 504, allowing manifold 112 to be molded as a single part without having to align multiple parts. The overall axial thickness of manifold 112, ribs 508, and the dimensions of bore 408 can vary based on optimization and specific applications. Additionally, the central circumferential section 506 of the manifold can have a tight or interference fit with a set of windings 512 (e.g., winding 104) of winding slot 510 to provide mechanical support to prevent the outer enamel coating of winding 104 from rubbing against the stator core. The features of manifold 112 that abut with windings 512 can be made of the same material as the rest of manifold 112, or can be made of a softer overmolding material (e.g., rubber).

[0032] These winding interface features, combined with manifold rib 508, structurally connect the winding slot 510 to the clamping-in eyelet. The manifold 112 is axially sealed against the stator core laminations by bolts 302, 304, 306, and hollow bolts 110. Sealing features (e.g., plastic ribs or seals and sealing grooves) and / or flexible polymer manifold material may be included to provide a sufficient seal.

[0033] The coolant distributed to the manifold 112 via the hollow bolt 110 can flow along the path indicated by arrow 551 (e.g., Figure 1The coolant flows along the path indicated by arrow 152. It can flow radially from the hollow bolt 110 between the plurality of ribs 508 to the inner surface 560 of the stator 102 (whose sealing air gap allows coolant to flow only into the slots). The coolant can then flow axially through the winding slots 510 to the end windings 512. The coolant can also flow circumferentially around the stator 102 at either or both of the clockwise and counterclockwise directions at the first circumferential section 502 and the second circumferential section 504.

[0034] More specifically, the manifold rib 508 can be configured to provide a series of interconnecting passages 550 extending around the edge of each winding slot 510 to allow coolant to circulate axially and radially around the winding 512. That is, in Figure 8 In the cross-sectional xy-plane shown, as indicated by reference axis 190, coolant can enter the passages 550 radially as indicated by the plurality of radial arrows 552. The coolant can be guided circumferentially around the end portion 553 of each passage 550. Coolant can also be guided between and along the windings 512, wherein the passages 550 extend in the axial direction (along the z-axis indicated in reference axis 190). Similarly, at the first circumferential section 502 and the second circumferential section 504, coolant can also be axially distributed in the same manner through passages 540 around portions of the stator core 503 (e.g., stator core 103) to approach the plurality of winding slots 510 at different axial locations along each winding slot (e.g., at different locations along the z-axis and the length of the stator core 503).

[0035] In this way, the coolant can be effectively guided around the winding 512 of each winding slot 510. By guiding the coolant radially, circumferentially, and axially around and along each winding slot 510 along the passage 550, the amount of heat transferred from the winding 512 of the winding slot 510 to the coolant can be increased compared to other cooling solutions that guide the coolant at other surfaces of the stator 102.

[0036] Figure 6 A perspective view 600 of a circumferential cross-section of manifold 112 is shown, wherein winding 104 partially obscures rib 508 at the central circumferential segment 506 of manifold 112. Coolant can flow circumferentially around manifold 112 and can be radially guided into a first passage 602 and a second passage 606, which can be... Figure 5A non-limiting example of passage 550. Coolant can be axially guided through the winding slots, meaning in the z-axis direction along the reference axis 190. Coolant can also be axially guided through the winding slots along a set of passages 610 of manifold 112 (e.g., at the second circumferential section 504 adjacent to air gap 160). Coolant can additionally flow circumferentially around the motor and radially from the first circumferential section 502 to the second circumferential section 504 and / or radially from the second circumferential section 504 to the first circumferential section 502 via the space 604 between the ribs 508. In other words, each winding slot (e.g., winding slot 510) is radially supplied from the first passage 602 and the second passage 606 in a small gap between the winding 104 and the manifold 112.

[0037] Figure 7 A planar cross-sectional perspective view 700 shows a portion of a manifold 112 including a passage 550 surrounding the winding 512 within the winding slot 510. Coolant circulates from the first circumferential section 502 to the second circumferential section 504 of the manifold 112 through a first passage 550 between a first rib 702 at the central circumferential section 506 and the winding 512, and through a second passage 550 between a second rib 704 of the manifold 112 and the winding 512 at the central circumferential section 506. A set of arrows 750 indicates the direction of coolant flow through the first and second passages 550. Flow can be directed upwards or downwards along the first and second passages 550, and can be directed between each of the windings 512 and at the end portions 553 of the passages 550 from the first rib 702 to the second rib 704 or from the second rib 704 to the first rib 702, as indicated by arrows 751 and 754. For example, coolant can flow down from the first circumferential section 502 to the second circumferential section 504 along the first passage 550, between the windings 512 and at the end portion 553 from the first rib 702 to the second rib 704, and along the second passage 550 from the second circumferential section 504 to the first circumferential section 502. Coolant can also flow circumferentially around the stator core at the first circumferential section 502, as indicated by arrow 753.

[0038] like Figure 8 and Figure 9 As shown, in some examples, manifold 112 may be formed from one or more different materials by means of stamping, for example, using two different stampings or a sub-stack of laminations. For example, one or more different materials may include electrical steel, aluminum, or different materials.

[0039] refer to Figure 8 The image shows a portion of a stamped cooling manifold 800 according to an example, wherein the stamped cooling manifold 800 may be... Figures 1 to 6A non-limiting example of the manifold 112. The stamped cooling manifold 800 includes a first circumferential section 802 and a second circumferential section 806, which may be the same as or similar to the first circumferential section 502 and the central circumferential section 506 of the manifold 112. See reference... Figure 5 As described, the second circumferential segment 806 may include a plurality of ribs 808 (e.g., ribs 508) that allow coolant to circulate around the winding slot 809, wherein a plurality of windings may be positioned between the ribs 808 and partially or completely enclosed by the ribs. To accommodate the winding slot 809, the stamped cooling manifold 800 may include a plurality of cut-out segments. The stamped cooling manifold 800 also includes a second plurality of cut-out segments 810 that allow coolant to flow circumferentially in a serpentine pattern between alternating and interconnected circumferential recesses formed by the cut-out segments 810 of each lamination, such as... Figure 9 As shown in more detail below. That is, the coolant can flow to the cut-out segment 810 as indicated by arrow 820, and then circumferentially through alternating and connected circumferential recesses as indicated by double-headed arrow 822; and also radially from said recesses into each winding slot 809, as indicated by arrow 824. Alternating and connected circumferential recesses can be added to the two sub-stacks, thereby allowing circumferential distribution of coolant while still maintaining continuous lamination. The recesses in the laminations can be connected to fluid passages (e.g., passages 113 and 118) of the hollow bolts, similar to those in the reference. Figures 1 to 7 The described plastic manifold 112. As described above, coolant can be supplied via bolt holes 812 passing through the stamped cooling manifold 800 (e.g., Figure 4 The hollow bolt (e.g., hollow bolt 110) of the fourth bolt hole 408 is introduced into the stamped cooling manifold 800.

[0040] Figure 9 The diagram shows a cooling manifold 800 that has been stamped. Figure 1 A perspective view 900 of a portion of the motor 100. An exemplary circumferential recess 912 is also shown. Figure 9 In the process, the stamped cooling manifold 800 includes a first sub-stack 904 laminated to a second sub-stack 906. To form a circumferential recess 912, a portion of the second sub-stack 906 has been removed at position 911. The circumferential recess 912 may be a plurality of overlapping circumferential recesses of the stamped cooling manifold 800. Figure 9 One of (not shown) allows coolant leaving one circumferential recess to flow into different circumferential recesses in opposing sub-stackings. For example, circumferential recess 912 may overlap with a second circumferential recess formed by removing a portion of the first sub-stacking 904.

[0041] The unfolded portion 980 of perspective view 900 shows a simplified alignment of a first portion 982 of the first sub-stack 904 with a second portion 984 of the second sub-stack 906 to form a circumferential recess 912 that extends circumferentially around the stator (e.g., in the x-direction). As can be seen, the removed portions of the first sub-stack 904 and the second sub-stack 906 are aligned such that coolant can flow in and out of the first recess 986 of the first sub-stack 904 and into the second recess 988 of the second sub-stack 906, as indicated by arrow 990. Coolant can also flow radially along the y-axis between different portions of the stator. In this way, the coolant follows a serpentine path through the middle portion of the stator in which sub-stacks 904 and 906 are positioned, wherein the serpentine path corresponds to the passage 550 around the winding 104. Figure 9 (Not shown in the image) Connection.

[0042] Figure 10 It shows Figure 1 A perspective view 1000 of motor 100, similar to Figure 6 A cross-sectional perspective view 600 shows the fluid passage 1002 within the slot extending from the first circumferential section 502 to the second circumferential section 504 (obstructed by a set of windings 104 of the manifold 112 via a rib 508 at the central circumferential section 506). To seal the fluid passage 1002 within the slot to prevent coolant leakage into the motor air gap 1006 between the stator 102 and the rotor, a sealing sleeve 1004 is circumferentially added at the inner diameter of the stator 102. The sealing sleeve 1004 can be an overmolded part (e.g., plastic or epoxy) or a glued-in sleeve, such as a carbon fiber sleeve. Additionally, to provide mechanical fixation for the multiple end windings 1020, one or more end rings 1022 may be added, such as… Figure 11 As shown in more detail below. The end ring 1024 may extend into some or all of the winding slot 510 to support the winding 104 positioned within the winding slot 510.

[0043] Figure 11 A portion 1100 of the stator 102, including an end winding 1102 of the stator 102, is shown. This end winding is compatible with… Figure 10The end winding 1020 depicted is identical. The end ring 1104 provides a tight or interference fit with the end winding 1102, which restricts the relative movement of each winding 104 relative to the others. Similar to the manifold 112, these features can be made of the base end ring material or added as a softer material via overmolding. Additionally, the end ring 1104 may include orifices to control the pressure in the fluid passage 1002 within the corresponding slot and to distribute coolant to the end winding 1102 for additional cooling. A sealing sleeve 1004 may be incorporated into both the manifold 112 and the end ring 1104.

[0044] Figure 12 Another example 1200 of a motor 100 including multiple cooling manifolds is shown. Specifically, a first end-ring manifold 1202 is included on a first end 1204 of the stator core 103, and a second end-ring manifold 1203 is included on a second end 1206 of the stator core 103, which are clamped downward by bolts 302, 304, 306 and hollow bolts 110, as described above. The first end-ring manifold 1202 and the second end-ring manifold 1203 may be the same as or similar to the centrally aligned cooling manifold 112. Similar to the manifold 112 and the non-manifold end ring 1104, the first end-ring manifold 1202 and the second end-ring manifold 1203 may be tightly fitted or interference-fitted with multiple stator core slots 311 to prevent relative movement of the windings 104. A sealing sleeve 1004 may abut against the first end-ring manifold 1202 and the second end-ring manifold 1203 to seal against leakage into the air gap 160. The first end annular manifold 1202 and the second end annular manifold 1203 can be supplied in a similar manner to manifold 112.

[0045] However, in Example 1200, coolant can flow alternately into the passages of the first end annular manifold 1202 and the second end annular manifold 1203. That is, coolant can flow to every other stator core slot 311, such that each stator core slot 311 is supplied by either the first end annular manifold 1202 or the second end annular manifold 1203. In this way, half of the stator core slot 311 is supplied from the first end 1204, and the other half from the second end 1206, thereby creating crossflow (e.g., where the coolant flow direction for one half of the slot 311 is from the first end 1204 to the second end 1206, and for the other half of the slot 311 it is from the second end 1206 to the first end 1204). For slots 311 to which the corresponding manifold does not supply coolant, an outlet feature (e.g., an orifice) may be included, such as... Figure 11 The end ring 1104. By integrating the manifold and end ring into two end manifolds instead of a single center manifold, the manufacturing complexity of the motor 100 can be reduced. For example, the stator core can be manufactured as a single assembly instead of having two sub-stacks, as described above.

[0046] Figure 13 An expanded view 1300 of the first end-ring manifold 1202 of Example 1200 is shown, illustrating how alternating windings can be cooled by alternating portions of the first end-ring manifold 1202. Expanded view 1300 shows a plurality of windings 1304, which may be... Figure 1 A non-limiting example of winding 104. Multiple windings 1304 include a first winding 1310, a second winding 1312, a third winding 1314, and a fourth winding 1316. The second winding 1312 and the fourth winding 1316 are cooled by a first end annular manifold 1202, while the first winding 1310 and the third winding 1314 are cooled by a second end annular manifold 1203. Figure 13 Cooling (not shown). That is, coolant enters the first end annular manifold 1202 from the radial hole 116 of the hollow bolt 110 via an orifice 1302 (e.g., orifice 122) in the first end annular manifold 1202. As coolant enters the first end annular manifold 1202, it can be directed to the second winding 1312 and the fourth winding 1316, as indicated by arrow 1320. However, the first end annular manifold 1202 may include a protrusion 1306 surrounding the first winding 1310 and the third winding 1314, which can prevent coolant circulation around the first winding 1310 and the third winding 1314 when the first end annular manifold 1202 is compressed against the corresponding laminations of the stator 102. Therefore, coolant may not cool the first winding 1310 and the third winding 1314. The second end annular manifold 1203 may include similar protrusions surrounding the second winding 1312 and the fourth winding 1316, such that the second winding 1312 and the fourth winding 1316 are not cooled by the second end annular manifold 1203 (because the second winding 1312 and the fourth winding 1316 are cooled by the first end annular manifold 1202), and the second end annular manifold 1203 may not include the protrusions surrounding the first winding 1310 and the third winding 1314, such that the first winding 1310 and the third winding 1314 are cooled by the second end annular manifold 1203. In this way, winding 1304 may be cooled alternately by the first end annular manifold 1202 or the second end annular manifold 1203.

[0047] Figure 14 It shows Figure 1Another example 1400 of the motor 100 includes a first end ring 1404 and a second end ring 1405. In example 1400, the stator 102 may have an interference fit with the housing 201. Due to the interference fit, bolts 302, 304, 306, and 110 are not used to secure the stator 102 to the housing 201. Coolant may flow into the cooling manifold 112 via an annular groove in the housing 201 instead of via coolant passages (such as coolant passage 113 of hollow bolt 110). The annular groove may allow coolant flow into a plurality of radial passages 1406 of the cooling manifold 112, which extend around each winding slot 510, as referenced above. Figure 5 and Figure 6 As described.

[0048] Figure 15 The diagram illustrates an extension 1500 of example 1400, where the extension 1500 shows an interface between the cooling manifold 112 and a plurality of windings 1502, which may be the same as or similar to the windings 104 of the winding slot 510. A plurality of radial passages 1406 extend from the outer circumference 1508 of the cooling manifold 112 into different slots of the windings 1502 (e.g., between different slots). Coolant can be directed along each radial passage 1406 to a corresponding winding slot 1516, as indicated by arrow 1520, whereby the coolant can cool the windings 1502 of the corresponding winding slot 1516. Radial passages 1406 may be included on both the first side 1510 and the second side 1512 of the cooling manifold 112. The number of radial passages 1406 may be one per slot 1516, as shown below. Figure 15 As indicated in the document.

[0049] Figure 16 An alternative example 1600 of the motor 100 is shown, wherein the circumferential channels 1602 of the cooling manifold 112 can circumferentially distribute coolant to all slots, as indicated by the bidirectional arrow 1620. In example 1600, the cooling manifold 112 may include a fewer number of radial channels 1406. As with the radial channels 1406, the circumferential channels 1602 may be included on both the first side 1610 and the second side 1612 of the cooling manifold 112. In the alternative example 1600, coolant may flow between each winding 1502 via a set of channels 1650 surrounding the windings 1502, as described above with reference to channel 550.

[0050] In another representation, the motor 100 may include a plurality of cooling manifolds 112, which may be positioned at various axial locations. For example, a first cooling manifold 112 may be included near a first end of the stator core 103, but still between sub-stacks of the core laminations; and a second cooling manifold 112 may be included near a second end of the stator core 103, but still between sub-stacks of the core laminations. In other examples, coolant may be introduced into the stator 102 from one or more end manifolds (e.g., a first end ring manifold 1202 and a second end ring manifold 1203), and the coolant may exit the stator 102 radially via a central manifold.

[0051] Therefore, a cooling manifold using a hollow bolt feed solution is proposed. This solution utilizes existing bolt structures and interfaces with the motor housing to form fluid pathways for guiding coolant into the internal portions of the motor stator. The hollow bolts form a sealed fluid interface without the need for additional seals, thus reducing motor manufacturing complexity. Slot-in-slot cooling using a manifold or multiple manifolds eliminates reliance on slot linings and varnishes for limiting relative movement of the stator windings and providing electrical isolation, while also cooling the hottest parts of the motor, significantly impacting the motor's thermal confinement capability. Furthermore, by guiding coolant circumferentially and radially around slots in the stator core, including the windings, heat can be extracted from the stator more efficiently and uniformly compared to alternative cooling solutions that rely on spraying coolant onto the surface of the stator, which may not be directed at the hottest central portion of the stator. By using hollow bolts, the proposed solution for cooling the stator does not rely on additional sealed interfaces in the motor, thus reducing manufacturing resources and maintaining the motor's performance. Coolant can be introduced into the stator core without stator interference fit, which may increase core losses in the motor. Additionally, the cooling manifold provides mechanical retention for the stator windings.

[0052] Furthermore, compared to other slot-based cooling solutions that enclose the end windings in a cover / manifold flow, the proposed solution has the advantage of not relying on slot epoxy overmolding and / or end winding covers. Cold coolant can be directly supplied to the hottest parts of the motor, and rotor cooling flow can be sprayed onto the end windings for additional cooling. The pressure drop in the coolant can be reduced because the centrally positioned cooling manifold creates a parallel flow branch at the center of the stator.

[0053] The technical advantage of cooling the motor by guiding the coolant to one or more of the proposed cooling manifolds via hollow stator bolts is that the coolant can be guided to the hottest part of the motor without relying on additional sealed coolant delivery interfaces with the motor housing.

[0054] Figures 1 to 16 Exemplary configurations of the relative positioning of various components are shown. If shown as directly contacting or directly connected to each other, such components may be referred to as directly contacting or directly connected, respectively, in at least one example. Similarly, in at least one example, components shown as adjacent to or next to each other may be adjacent to or next to each other, respectively. As an example, components in coplanar contact with each other may be referred to as being in coplanar contact. As another example, in at least one example, components positioned apart from each other with only space between them and no other components may be referred to as such. As yet another example, components shown as above / below each other, on opposite sides of each other, or to the left / right of each other may be referred to as such relative to each other. Furthermore, as shown in the figures, in at least one example, the topmost component or the apex of a component may be referred to as the “top” of the component, and the bottommost component or the lowest point of a component may be referred to as the “bottom” of the component. As used herein, top / bottom, upper / lower, above / below may be relative to the vertical axis of the figures and are used to describe the positioning of the components of the figures relative to each other. For this purpose, in one example, a component shown above other components is vertically positioned above the other components.

[0055] This disclosure also provides support for a cooling system for an electric motor having a stator and a housing, the cooling system comprising: a cooling manifold positioned at an axial center of the stator and coaxially aligned with the central axis of the stator; and bolts clamping the stator to the housing, the bolts including a hollow section including a fluid inlet and a fluid outlet configured to deliver coolant from the hollow section to multiple passages in the cooling manifold. In a first example of the system, the hollow section includes a first portion extending into the housing and a second portion extending into the stator core of the motor, the second portion including one or more radial holes circumferentially positioned around respective sides of the hollow section, the one or more radial holes being positioned to allow coolant to flow from a central passage of the hollow section to a passage between stator core lugs of the motor and the outer circumference of the hollow section. In a second example of the system (optionally including the first example), the passage is sealed to the head of the bolt and the housing by the clamping force of the bolt, and the bolt includes a lip around the outer circumference of the bolt, the lip sealing the passage at the interface between the housing and the stator core. In a third example of the system (optionally including one or both of the first and second examples), the plurality of passages of the cooling manifold are axially sealed against the laminations of the stator core by compression of the plurality of bolts including the bolt. In a fourth example of the system (optionally including one or more or each of the first to third examples), the cooling manifold is in fluid communication with the fluid outlet, and the cooling manifold includes a partially open compression-restricting orifice of the bolt hole through which coolant is transferred from the fluid outlet of the hollow section to the radial inlet of the cooling manifold. In a fifth example of the system (optionally including one or more or each of the first to fourth examples), the compression limiting orifice includes a pin feature extending partially into portions of the plurality of stator core slots, the pin feature aligning the cooling manifold with the plurality of stator core slots. In a sixth example of the system (optionally including one or more or each of the first to fifth examples), the cooling manifold extends radially and inwardly into the plurality of stator core slots to form an interference fit with the windings of the stator.In a seventh example of the system (optionally including one or more or each of the first to sixth examples), the cooling manifold is made of injection-molded plastic and further includes: a first axial section that distributes the coolant circumferentially around the stator to the plurality of stator core slots at the outer circumference of the cooling manifold; a second axial section that distributes the coolant circumferentially around the stator to the plurality of stator core slots at the inner circumference of the cooling manifold; and a central axial section including a plurality of radial ribs, each radial rib being a mechanical retaining feature connecting the first axial section to the second axial section, such that the cooling manifold can be molded as a single part. In the eighth example of the system (optionally including one or more or each of the first to seventh examples), the central axial segment has an interference fit with the winding to provide the mechanical support required to prevent the outer enamel coating of the winding from rubbing against the stator core, and the feature of the cooling manifold that abuts the winding is made of an overmolded material that is softer than the material of the cooling manifold. In the ninth example of the system (optionally including one or more or each of the first to eighth examples), the cooling manifold is made of electrical steel or aluminum and also includes two laminated stacks comprising alternating and connected circumferential recesses to allow the coolant to be distributed circumferentially while still maintaining continuous laminations. In a tenth example of the system (optionally including one or more or each of the first to ninth examples), the system further includes: a first cooling manifold located at a first end of the stator core; and a second cooling manifold located at a second end of the stator core, wherein coolant flows alternately into the passages of the first cooling manifold and the second cooling manifold such that each slot of the stator core is supplied by one of the first cooling manifold and the second cooling manifold.

[0056] This disclosure also provides support for a system comprising: an electric motor including a stator; a cooling system configured to allow coolant to flow from a coolant pump to the stator; and a bolt connecting the cooling system to the electric motor, the bolt including a hollow section having one or more radial holes positioned around the outer circumference of the hollow section, the one or more radial holes being positioned to allow coolant to flow from the hollow section to a cooling manifold of the electric motor via a passage between a stator lug of the electric motor and the outer circumference of the hollow section. In a first example of the system, the cooling manifold includes a partially open compression-restricting orifice of the bolt hole through which coolant is transferred from the passage to a radial inlet of the cooling manifold. In a second example of the system (optionally including the first example), the cooling manifold extends radially and inwardly into a plurality of stator slots of the stator to form an interference fit with the windings of the stator. In a third example of the system (optionally including one or both of the first and second examples), the system further includes a sealing sleeve positioned at the inner diameter of the stator to seal the fluid passage within the slot of the cooling manifold to prevent coolant leakage into the motor air gap between the stator and rotor of the motor. In a fourth example of the system (optionally including one or more of the first to third examples), the system further includes a plurality of end rings positioned at end windings of the stator to provide mechanical fixation to the end windings via an interference fit to limit relative movement of the end windings. The plurality of end rings include orifices to control pressure in the fluid passage within the slot and to distribute the coolant to the end windings. In a fifth example of the system (optionally including one or more of the first to fourth examples), the cooling manifold includes two laminated stacks comprising alternating and connected circumferential recesses that circumferentially distribute the coolant throughout the cooling manifold while maintaining continuous laminations. In a sixth example of the system (optionally including one or more or each of the first to fifth examples), the motor includes: a first cooling manifold positioned at a first end of the stator core of the stator; and a second cooling manifold positioned at a second end of the stator core, wherein the coolant flows alternately into the passages of the first cooling manifold and the second cooling manifold such that each slot of the stator core is supplied by either the first cooling manifold or the second cooling manifold.

[0057] This disclosure also provides support for a method for cooling an electric motor, the method comprising: allowing coolant to flow through a plurality of circumferential and radial passages of a cooling manifold via a hollow section of bolts clamping the stator to the motor housing, the cooling manifold being positioned at an axial center of the stator of the motor and coaxially aligned with the central axis of the stator, the cooling manifold extending radially and inwardly into a plurality of slots in the stator core of the motor to form an interference fit with the windings of the stator. In a first example of the method, the method further comprises: allowing coolant to flow from the hollow section to a passage between stator core lugs and the outer circumference of the hollow section via one or more radial holes circumferentially positioned around each side of the hollow section, the passage being sealed to the head of the bolts and the housing by the clamping force of the bolts, and allowing coolant to flow from the passage to a radial inlet of the cooling manifold via partially open compression-limiting orifices in the bolt holes of the cooling manifold.

[0058] In another representation, a hybrid vehicle includes: an engine and an electric motor, the electric motor including a rotor positioned within a stator and an in-slot cooling system adapted to cool a plurality of stator windings extending through stator slots in the stator, wherein the in-slot cooling system includes: a cooling manifold positioned at an axial center of the stator and coaxially aligned with the central axis of the stator; and bolts clamping the stator to the housing, the bolts including a hollow section including a fluid inlet and a fluid outlet configured to deliver coolant from the hollow section to a plurality of passages in the cooling manifold.

[0059] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific examples should not be considered limiting, as numerous variations are possible. For example, the above techniques can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or properties.

[0060] The appended claims specifically point to certain combinations and sub-combinations considered novel and non-obvious. These claims may refer to an "a" element or a "first" element or its equivalents. Such claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amending these claims or by setting new claims in this application or related applications. Such claims, whether broader, narrower, equivalent, or different in scope from the original claims, are also considered to be included within the subject matter of this disclosure. According to the invention, a cooling system for an electric motor having a stator and a housing is provided, comprising: a cooling manifold positioned at the axial center of the stator and coaxially aligned with the central axis of the stator; and bolts clamping the stator to the housing, the bolts including a hollow section including a fluid inlet and a fluid outlet configured to transfer coolant from the hollow section to a plurality of passages in the cooling manifold.

[0061] According to one embodiment, the hollow section includes a first portion extending into the housing and a second portion extending into the stator core of the motor, the second portion including one or more radial holes circumferentially positioned around each side of the hollow section, the one or more radial holes being positioned to allow the coolant to flow from a central passage of the hollow section to a passage between the stator core lugs of the motor and the outer circumference of the hollow section.

[0062] According to one embodiment, the passage is sealed to the head of the bolt and the housing by the clamping force of the bolt, and the bolt includes a lip around the outer circumference of the bolt, the lip sealing the passage at the interface between the housing and the stator core.

[0063] According to one embodiment, the plurality of passages of the cooling manifold are axially sealed against the laminations of the stator core by compression of a plurality of bolts including the bolts.

[0064] According to one embodiment, the cooling manifold is in fluid communication with the fluid outlet, and the cooling manifold includes a partially open compression-restricting orifice with bolt holes through which coolant is transferred from the fluid outlet of the hollow section to the radial inlet of the cooling manifold.

[0065] According to one embodiment, the compression limiting orifice includes a pin feature that extends partially into portions of a plurality of stator core slots, the pin feature aligning the cooling manifold with the plurality of stator core slots.

[0066] According to one embodiment, the cooling manifold extends radially and inwardly into the plurality of stator core slots to form an interference fit with the windings of the stator.

[0067] According to one embodiment, the cooling manifold is made of injection-molded plastic and further includes: a first circumferential section that distributes the coolant circumferentially around the stator to the plurality of stator core slots at the outer circumference of the cooling manifold; a second circumferential section that distributes the coolant circumferentially around the stator to the plurality of stator core slots at the inner circumference of the cooling manifold; and a central circumferential section including a plurality of radial ribs, each radial rib being a mechanical retaining feature connecting the first circumferential section to the second circumferential section, such that the cooling manifold is formed as a single part.

[0068] According to one embodiment, the central circumferential section has an interference fit with the winding to provide the mechanical support required to prevent the outer enamel coating of the winding from rubbing against the stator core, and the feature of the cooling manifold that abuts the winding is made of an overmolding material that is softer than the material of the cooling manifold.

[0069] According to one embodiment, the cooling manifold is made of electrical steel or aluminum and also includes two laminated stacks that include alternating and connected circumferential recesses to allow the coolant to be distributed circumferentially while still maintaining continuous laminations.

[0070] According to one embodiment, the invention is further characterized by: a first cooling manifold located at a first end of the stator core; and a second cooling manifold located at a second end of the stator core, wherein coolant flows alternately into the passages of the first cooling manifold and the second cooling manifold, such that each slot of the stator core is supplied by one of the first cooling manifold and the second cooling manifold.

[0071] According to the present invention, a system is provided comprising: an electric motor including a stator; a cooling system configured to allow coolant to flow from a coolant pump to the stator; and a bolt connecting the cooling system to the electric motor, the bolt including a hollow section having one or more radial holes positioned around the outer circumference of the hollow section, the one or more radial holes being positioned to allow the coolant to flow from the hollow section to a cooling manifold of the electric motor via a passage between a stator lug of the electric motor and the outer circumference of the hollow section.

[0072] According to one embodiment, the cooling manifold includes a partially open compression-restricting orifice with bolt holes through which coolant is transferred from the passage to the radial inlet of the cooling manifold.

[0073] According to one embodiment, the cooling manifold extends radially and inwardly into a plurality of stator core slots of the stator to form an interference fit with the windings of the stator.

[0074] According to one embodiment, the invention is further characterized by: a sealing sleeve positioned at the inner diameter of the stator to seal the fluid passage within the slot of the cooling manifold to prevent coolant leakage into the motor air gap between the stator and rotor of the motor.

[0075] According to one embodiment, the invention is further characterized by: a plurality of end rings positioned at the end windings of the stator to provide mechanical fixation to the end windings via an interference fit to limit relative movement of the end windings, the plurality of end rings including orifices to control pressure in the fluid passage within the slot and to distribute the coolant to the end windings.

[0076] According to one embodiment, the cooling manifold includes two laminated stacks, the two laminated stacks including alternating and connected circumferential recesses, the alternating and connected circumferential recesses distributing the coolant circumferentially throughout the cooling manifold while maintaining continuous laminations.

[0077] According to one embodiment, the motor includes: a first cooling manifold positioned at a first end of the stator core of the stator; and a second cooling manifold positioned at a second end of the stator core, wherein the coolant flows alternately into the passages of the first cooling manifold and the second cooling manifold, such that each slot of the stator core is supplied by either the first cooling manifold or the second cooling manifold.

[0078] According to the present invention, a method for cooling an electric motor includes: allowing coolant to flow through a plurality of circumferential and radial passages of a cooling manifold via a hollow portion of a bolt clamping the stator to the housing of the motor, the cooling manifold being positioned at the axial center of the stator of the motor and coaxially aligned with the central axis of the stator, the cooling manifold extending radially and inwardly into a plurality of slots in the stator core of the motor to form an interference fit with the windings of the stator.

[0079] In one aspect of the invention, the method includes: allowing coolant to flow from the hollow section to a passage between a stator lug hole of the motor and the outer circumference of the hollow section via one or more radial holes circumferentially positioned around each side of the hollow section, the passage being sealed to the head of the bolt and the housing by the clamping force of the bolt, and allowing coolant to flow from the passage to a radial inlet of the cooling manifold via a partially open compression-restricting orifice of the bolt hole of the cooling manifold.

Claims

1. A cooling system (24) for an electric motor (14, 100) having a stator (102) and a housing (201), said cooling system (24) comprising: Cooling manifolds (112, 800) are positioned at the axial center of the stator (102) and coaxially aligned with the central axis (390) of the stator (102); and Bolts (110) clamp the stator (102) to the housing (201), the bolts (110) including a hollow section including a fluid inlet and a fluid outlet configured to transfer coolant from the hollow section to multiple passages (550, 1650, 610) of the cooling manifold (112, 800).

2. The cooling system (24) of claim 1, wherein the hollow section includes a first portion (117) extending into the housing (201) and a second portion (119) extending into the stator core (503, 103) of the motor (14, 100), the second portion (119) including one or more radial holes (116) circumferentially positioned around each side of the hollow section, the one or more radial holes (116) being positioned to allow the coolant to flow from the central passage (113) of the hollow section to a passage (118) between the stator core lug (121) of the motor (14, 100) and the outer circumference (120) of the hollow section.

3. The cooling system (24) of claim 2, wherein the passage (118) is sealed to the head (130) of the bolt (110) and the housing (201) by the clamping force of the bolt (110), and the bolt (110) includes a lip (220) surrounding the outer circumference (120) of the bolt (110), the lip sealing the passage (118) at the interface between the housing (201) and the stator core (103).

4. The cooling system (24) of claim 2, wherein the plurality of passages (550, 1650, 610) of the cooling manifold (112, 800) are sealed against the laminations of the stator core (503, 103) by compression of a plurality of bolts (302) including the bolt (110).

5. The cooling system (24) of claim 2, wherein the cooling manifold (112, 800) is in fluid communication with the fluid outlet, and the cooling manifold (112, 800) includes a partially open compression-restricting orifice (312) of a bolt hole (309) through which coolant is transferred from the fluid outlet of the hollow section to the radial inlet of the cooling manifold (112, 800).

6. The cooling system (24) of claim 5, wherein the compression limiting orifice (312) includes a pin feature that extends partially into a portion of a plurality of stator core (503, 103) slots (311), the pin feature aligning the cooling manifold (112, 800) with the plurality of stator core slots (311).

7. The cooling system (24) of claim 6, wherein the cooling manifolds (112, 800) extend radially and inwardly into the plurality of stator core slots (311) to form an interference fit with the windings (1502, 1304, 512, 104) of the stator (102).

8. The cooling system (24) of claim 7, wherein the cooling manifolds (112, 800) are made of injection-molded plastic, and further comprising: The first circumferential section (802, 502) distributes the coolant circumferentially to the plurality of stator core slots (311) at the outer circumference (1508) of the cooling manifold (112, 800) around the stator (102); The second circumferential section (806, 504) distributes the coolant circumferentially to the plurality of stator core slots (311) at the inner circumference of the cooling manifold (112, 800) around the stator (102); and A central circumferential section (506) includes a plurality of radial ribs (508, 808), wherein each radial rib (508) is a mechanical retaining feature connecting the first circumferential section (802, 502) to the second circumferential section (806, 504), such that the cooling manifold (112, 800) is formed as a single part.

9. The cooling system (24) as claimed in claim 8, wherein: The central circumferential section (506) has an interference fit with the windings (1502, 1304, 512, 104) to provide the mechanical support required to prevent the outer enamel coating of the windings (1502, 1304, 512, 104) from rubbing against the stator core (503, 103), and the features of the cooling manifolds (112, 800) that abut with the windings (1502, 1304, 512, 104) are made of an overmolding material that is softer than the material of the cooling manifolds (112, 800).

10. The cooling system (24) of claim 1, wherein the cooling manifold (112, 800) is made of electrical steel or aluminum and further comprises two laminate stacks (904) comprising alternating and connected circumferential recesses to allow the coolant to be distributed circumferentially while still maintaining continuous laminations.

11. The cooling system (24) as claimed in claim 2, further comprising: A first cooling manifold (112, 800) is positioned at a first end (1204) of the stator core (503, 103); and a second cooling manifold (112, 800, 112) is positioned at a second end (1206) of the stator core (103), and the coolant flows alternately to passages (550, 1650, 610) of the first cooling manifold (112, 800) and the second cooling manifold (112, 800) such that each slot (1516) of the stator core (503, 103) is supplied by either the first cooling manifold (112, 800) or the second cooling manifold (112, 800).

12. A system comprising: Motors (14, 100), including stator core (102); Cooling system (24), the cooling system being configured to allow coolant to flow from a coolant pump to the stator (102); and Bolts (110) that connect the cooling system (24) to the motor (14, 100) include a hollow section having one or more radial holes (116) positioned around the outer circumference (120) of the hollow section, the one or more radial holes (116) being positioned to allow the coolant to flow from the hollow section to the cooling manifold (112, 800) of the motor (14, 100) via a passage (118) between the stator lug (121) of the motor (14, 100) and the outer circumference (120) of the hollow section.

13. The system of claim 12, wherein the cooling manifold (112, 800) includes a partially open compression-restricting orifice (312) of a bolt hole (309), through which coolant is transferred from the passage (118) to the radial inlet of the cooling manifold (112, 800).

14. The system of claim 12, wherein the cooling manifolds (112, 800) extend radially and inwardly into a plurality of stator core slots (311) of the stator (102) to form an interference fit with the windings (1502, 1304, 512, 104) of the stator (102).

15. The system of claim 12, further comprising: A sealing sleeve (1004) is positioned at the inner diameter of the stator (102) to seal the fluid passages (550, 1650, 610) within the slots of the cooling manifolds (112, 800) to prevent coolant leakage into the motor air gap (160, 1006) between the stator (102) and the rotor of the motor (14, 100).

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