Method for manufacturing composite stator sleeve

Abstract

A method for manufacturing a stator sleeve comprises first wrapping a cylindrical mandrel with heated prepreg tape using automated fiber placement. The prepreg tape comprises a continuous fiber reinforcement within a polymer matrix. Next, the cylindrical mandrel is cooled and removed from the wrapped prepreg tape, resulting in a cylindrical unfinished stator sleeve. Each end of the unfinished stator sleeve is trimmed. Next, a cylindrical fixing tool is used to place a first end ring and a second end ring against the first and second ends of the trimmed stator sleeve, respectively. The first and second end rings are made of the same material as the polymer matrix of the prepreg tape. Finally, the first and second end rings are laser welded or melt bonded to the first and second ends of the trimmed stator sleeve.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This non-provisional application claims priority to provisional application 63 / 365,308, filed May 25, 2022, the entire contents of which are fully incorporated herein by these references. Technical Field

[0003] The present invention generally relates to stator sleeves for use in electric machines. More particularly, the present invention relates to methods of making composite stator sleeves for use in high performance electric machines having liquid cooled stators. Background Art

[0004] Generally speaking, electric motors have several key components that enable them to efficiently and effectively convert electrical energy into mechanical energy. Each component contributes to the crucial interaction between the motor's magnetic field and the current in its windings, which in turn generates force in the form of shaft rotation. It is this mechanical energy generated by this shaft rotation that helps keep electric vehicles or factory operations running smoothly. These components can include the rotor, stator, support structure, windings, and air gap.

[0005] Rotor: The rotor is the moving part of the motor. It turns the shaft, which transmits the aforementioned mechanical power. In a typical configuration, the rotor is lined with conductors that carry an electric current, which then interacts with the stator's magnetic field to generate the force that turns the shaft. However, some rotors carry permanent magnets, while the stator holds the conductors.

[0006] Stator and stator core: The stator is the stationary component of the motor's electromagnetic circuit and typically contains windings or permanent magnets. The stator core is made up of many thin metal sheets, called a laminate. This laminate reduces energy losses that occur when using a solid iron core.

[0007] Support Structures: The rotor in an electric motor is supported by support structures that allow it to rotate about its axis. These support structures, in turn, are supported by the motor housing. The motor shaft extends through the support structures to the exterior of the motor, where the load is applied. Because the load's force is applied outside the outermost support structures, the load is said to be "overhanging."

[0008] Windings: Windings are wires laid out in coils, typically around a laminated soft iron core, to form magnetic poles when energized by an electric current. Electric motors have two basic magnetic pole configurations: salient and non-salient. In salient-pole motors, the pole's magnetic field is generated by windings wrapped around the pole below the pole face. In non-salient-pole motors, the windings are distributed across the pole face slots.

[0009] Air Gap: Although not a physical component, the air gap is the distance between the rotor and stator. The air gap in a motor has a significant impact and is generally kept as small as possible, as a large air gap has a significant negative impact on performance. This is a primary cause of low power factor when the motor is operating. Because magnetizing current increases with air gap, the air gap should be minimized. However, very small gaps can cause mechanical interference issues.

[0010] High performance electric motors can generate a lot of heat, especially in the conductors. Therefore, many high performance electric motors are configured with the rotor carrying permanent magnets and the stator holding the conductors. Liquid cooling can then be used to directly cool the conductors, resulting in a liquid cooled stator. A stator sleeve can be used to separate the stator from the rotor, enabling the use of a fluid coolant. Such liquid cooled electric motors can be used in applications such as electric vehicles, where high efficiency and power to weight ratio are important. Suitable inner rotor / outer stator electric motors include, but are not limited to, induction motors (IM), embedded permanent magnet motors (IPM), synchronous reluctance motors (SynRM), and embedded permanent magnet-synchronous reluctance motors (IPM-SynRM). In addition, outer rotor / inner stator electric motors (such as wheel hub motors) can benefit from the present invention.

[0011] Stator sleeves are known in the prior art. For example, US2003 / 0193260 teaches a powdered metal stator sleeve. Metal stator sleeves are not ideal due to their electrical conductivity and the eddy current losses that reduce the efficiency of the motor.

[0012] US 8,378,550 B2 teaches a stator sleeve that is located outside the stator windings, rather than between the stator and rotor as in the present invention. This coolant approach is not as effective as immersing the stator windings in coolant as in the present invention.

[0013] Application DE102020119110A1 teaches a stator sleeve which attempts to solve the cooling problem of high performance electric machines. However, as discussed further below, the present application improves upon this teaching in a number of ways.

[0014] The purpose of a stator sleeve is to create a barrier between the stator and rotor in an electric motor, allowing coolant to flow through the stator for cooling, thereby improving motor efficiency. Therefore, there is a need for an improved stator sleeve that can enable improved, high-performance electric motors. The present invention satisfies these needs and provides other related advantages. Summary of the Invention

[0015] An exemplary embodiment of the present invention is a method for manufacturing a stator sleeve, wherein the stator sleeve is configured to be assembled as part of a cooled electric machine having a stator and a rotor, the stator having a fixed conductor with a winding, the rotor having a rotating permanent magnet, and wherein a coolant liquid is configured to cool the fixed conductor with the winding. The method for manufacturing the stator sleeve includes the following steps: providing a cylindrical mandrel; winding the cylindrical mandrel with a prepreg tape using an automated fiber placement, the automated fiber placement being in-situ consolidation, wherein the prepreg tape includes a continuous fiber reinforcement material within a polymer matrix; heating the prepreg tape during the automated fiber placement; cooling the wound prepreg tape by waiting for an elapsed time; removing the cylindrical mandrel from the wound prepreg tape to obtain a cylindrical unfinished stator sleeve; trimming each end of the unfinished stator sleeve to obtain a trimmed stator sleeve, the trimmed stator sleeve having a first end and an opposite end. providing a first end ring and a second end ring, wherein the first end ring and the second end ring both comprise a polymer, wherein the polymer of the first end ring and the second end ring is the same material as the polymer matrix of the prepreg tape; using a cylindrical fixing tool to abut the first end ring and the second end ring against the first end and the second end of the trimmed stator sleeve, respectively; and laser welding or fusion bonding the first end ring and the second end ring to the first end and the second end of the trimmed stator sleeve, respectively, thereby forming a completed stator sleeve, wherein the completed stator sleeve is configured to be installed in a cooled electric machine.

[0016] Alternative embodiments will now be described. The prepreg tape winding of the continuous fiber reinforcement may be in a toroidal winding orientation. The continuous fiber reinforcement may include S2 glass, IM7 carbon, and / or boron. The polymer matrix may include PA, PET, PBT, POM, PPS, PEEK, PAEK, and / or PEKK.

[0017] Heating of the prepreg tape during automated fiber placement may include hot air torch convection heating, laser heating, flash lamp heating, or infrared heating.

[0018] The first and second end rings may include a carbon black filled polymer.

[0019] The stator sleeve may be impermeable to the coolant liquid.

[0020] The prepreg tape may be unidirectional.

[0021] The step of removing the cylindrical mandrel from the wrapped prepreg tape may include cooling the cylindrical mandrel to cause it to shrink and reduce in size. Cooling the cylindrical mandrel may include flowing a cooling liquid through the cylindrical mandrel.

[0022] The step of removing the cylindrical mandrel from the wrapped prepreg tape may include dissolving the cylindrical mandrel in a liquid configured to dissolve a material of the cylindrical mandrel.

[0023] The step of removing the cylindrical mandrel from the wound prepreg tape may include disintegrating the cylindrical mandrel.

[0024] An exemplary embodiment of the present invention is a method of manufacturing a stator sleeve, wherein the stator sleeve is configured to be assembled as part of a cooled electric machine having a stator and a rotor, the stator having a stationary conductor with a winding, the rotor having rotating permanent magnets, and wherein a coolant liquid is configured to cool the stationary conductor with the winding. The method of manufacturing a stator sleeve comprises the following steps: providing a cylindrical mandrel; winding the cylindrical mandrel with a prepreg tape using automated fiber placement; wherein the prepreg tape comprises a continuous fiber reinforcement material within a polymer matrix; heating the prepreg tape during automated fiber placement; cooling the wound prepreg tape by waiting for an elapsed time; removing the cylindrical mandrel from the wound prepreg tape to obtain a cylindrical unfinished stator sleeve, wherein the cylindrical unfinished stator sleeve is not fully consolidated; providing an outer mold, the outer mold defining an outer surface of the completed stator sleeve; placing the cylindrical unfinished stator sleeve; inserting a deformable bladder into the composite sleeve; pressurizing the deformable bladder; heating the assembly, the assembly comprising the outer mold, the cylindrical unfinished stator sleeve and the deformable bladder, wherein the unfinished stator sleeve is fully consolidated, An unfinished stator sleeve is obtained; the assembly is cooled; the unfinished stator sleeve is removed from the outer mold and the deformable bag is removed; each end of the unfinished stator sleeve is trimmed to obtain a trimmed stator sleeve having a first end and an opposite second end; a first end ring and a second end ring are provided, wherein the first end ring and the second end ring both include a polymer, wherein the polymer of the first end ring and the second end ring is the same material as the polymer matrix of the prepreg tape; the first end ring and the second end ring are respectively pressed against the first end and the second end of the trimmed stator sleeve using a cylindrical fixing tool; and the first end ring and the second end ring are respectively laser welded or melt-bonded to the first end and the second end of the trimmed stator sleeve to form a completed stator sleeve, wherein the completed stator sleeve is configured to be installed in a cooled electric motor.

[0025] Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is illustrated in the accompanying drawings. In these drawings:

[0027] Figure 1 shows a cross-sectional view of the motor;

[0028] Figure 2A It is a diagram of the in-situ consolidation (ISC) process;

[0029] Figure 2B is with Figure 2AA simplified side view similar to that of the illustration showing the in-situ consolidation process;

[0030] Figure 3 is an embodiment of a cylindrical sleeve removed from a cylindrical mandrel;

[0031] Figure 4A A grooved compaction roller is shown;

[0032] Figure 4B The axial features added to the stator sleeve are shown;

[0033] Figure 5A A first end ring of the stator sleeve is shown;

[0034] Figure 5B The second end ring of the stator sleeve is shown;

[0035] Figure 6A It shows Figure 5A An enlarged cross-sectional view of a structure attached to one end of a stator sleeve;

[0036] Figure 6B It shows Figure 5B An enlarged cross-sectional view of a structure attached to the other end of the stator sleeve;

[0037] Figure 7 is an isometric view showing the use of a cylindrical fixing tool to position the end ring relative to the stator sleeve;

[0038] Figure 8 yes Figure 7 A front view of the structure, where laser energy is now applied to the end fittings and stator sleeve using a laser welding machine;

[0039] Figure 9 yes Figure 8 Side view of

[0040] Figure 10 is an isometric view of the completed stator sleeve of the present invention;

[0041] Figure 11 It is a simplified representation of another innovative method of the present invention utilizing bladder molding;

[0042] Figure 12 is a perspective view of a simplified pouch mold of the present invention;

[0043] Figure 13 Shown Figure 12 the mold in which the sleeve and bladder are now inserted;

[0044] Figure 14 Shown Figure 13 A structure in which the pouch mold is pressurized and heated;

[0045] Figure 15 Shown Figure 14 cooling and decompression of structures; and

[0046] Figure 16 The resulting sleeve is shown, which can be trimmed and attached to the end ring as previously described herein. DETAILED DESCRIPTION

[0047] Composite materials have been progressively adopted into commercial aircraft. At each stage, composites have demonstrated their ability to form an increasing number of flight-critical components with the required strength, stiffness, and near-freedom from defects (surface porosity as well as invisible internal voids) that could be a source of future damage as the aircraft ages. Until recently, this near-void-free standard (<1% porosity) was maintained by combining vacuum bag consolidation with exposure to high temperatures and pressures in an autoclave, typically for several hours during the curing process. In recent years, the development of oven-cured resins (systems that can cure to acceptable void contents without an autoclave) has helped shorten cure cycles and, because ovens are less expensive to operate than autoclaves, can reduce the time and expense required to produce parts. At the same time, automated filament winding, automated tape laying (ATL), and automated fiber placement (AFP) equipment have replaced manual layup in many applications, significantly increasing the speed at which parts are laid up. While these systems are equipped with rollers that compact the material immediately after layup to ensure adhesion and avoid the formation of air pockets that can cause voids, consolidation of the laminate typically still occurs in the second step of those two-step processes, either under a vacuum bag, in an autoclave, oven, or other heating device (e.g., a heated tool). This state of the art persists, at least in part, because today's certified aerospace composites are primarily based on thermosets.

[0048] There is an alternative approach. It’s called in-situ consolidation, meaning, consolidated in place. The key is to use a thermoplastic matrix rather than a thermoset matrix. Thermoplastics are liquid when heated to their melting temperature and solidify when cooled, but do not need to cross-link like thermosets. Consolidation of the thermoplastic composite (TPC) can then be achieved by rapidly heating the impregnated reinforcement material to the melting temperature of the thermoplastic polymer matrix and then applying pressure as the tape or tow is laid down onto the tool and / or previously laid laminate. True in-situ consolidation (ISC) is a one-step process (no further heating or pressurizing steps are required after fiber placement or tape laying is complete).

[0049] The impact of eliminating an entire, expensive step in the manufacturing process is so significant and obvious that one might ask why isn't everyone doing it already? One reason (and there are others, which will be discussed) is that change is very expensive in the aerospace industry. Substituting materials inevitably requires extensive and expensive testing and requalification.

[0050] That being said, two-step consolidation TPCs are already being used in select aircraft applications. Although their processing temperatures are much higher than thermosets (nearly 400°C versus 180°C / 350°F for primary structures), cycle times are much shorter because TPCs only require cooling, not cross-linking. Thermoplastics are also inherently tough and don’t require special formulations to provide the fatigue resistance necessary for aircraft applications. Furthermore, because thermoplastics can be reheated and reshaped, they can be welded (a cost-effective, fastener-free assembly option). As the aircraft industry pursues materials and processing options that can achieve production rates of at least 60 aircraft per month and support the digital manufacturing, multifunctional structures, and sustainability envisioned as essential for next-generation aircraft, TPCs have become a frontrunner. TPCs have been the material of choice in most recently completed large-scale aircraft demonstration programs.

[0051] The inventors of the present invention have extensive experience in the aerospace industry and understand that automating the manufacturing process for thermoplastics through automated tape placement (ATP) can increase productivity, reduce labor costs, and improve geometric feature repeatability compared to traditional hand layup. Now, the inventors have turned their attention to improving electric motors, which are widely used in high-performance applications.

[0052] The present invention improves upon the prior art by: incorporating end features for ease of connection to the stator, fluid sealing, and ease of assembly; optionally incorporating axial features on the outer diameter for ease of assembly, coolant flow channels, stator winding spacers, and reinforcement members; utilizing thermoplastic polymer composites to hold the entire structure together, providing excellent coolant / solvent resistance, allowing for high-rate manufacturing, and allowing for recycling at the end of its useful life; providing innovative manufacturing methods to facilitate the manufacture of optimized stator sleeves; and efficiently manufacturing complex stator sleeve assemblies at high rates.

[0053] As mentioned previously, the purpose of the stator sleeve is to create a barrier between the stator and rotor in the electric machine to allow coolant to flow through the stator for cooling. Figure 1 The general configuration is shown as an enlarged cross-sectional view of an interior permanent magnet motor (IPM). Figure 1A cross-sectional view of an electric machine 10 is shown having a housing 11, a stator 12, windings 13, a rotor 14, a rotor sleeve 15, a stator sleeve 16, and permanent magnets 17. It will be appreciated that some electric machines may include a stator sleeve but not a rotor sleeve.

[0054] The stator sleeve 16 of the present invention is ideally made with thin walls. This results in a smaller gap between the stator and the rotor, which improves efficiency. The stator sleeve has high strength and stiffness. This allows for thinner walls and minimal deformation of the sleeve during use. The stator sleeve is not permeable to coolant, so fluid leakage through the material of the stator sleeve is not a problem. The stator sleeve has low magnetic permeability so that it does not interfere with the magnetic field between the rotor and the stator. The stator sleeve also has low electrical conductivity, which results in low electrical losses due to eddy currents. The stator sleeve combines the following features, such as: end fittings for connecting to the stator and for sealing purposes; structures for coolant flow channels, reinforcement, integration with the stator windings, etc.; and mounting structures for easy assembly, alignment, etc.

[0055] Those skilled in the art who have read the present disclosure will appreciate that the liquid permeability of the stator of the present invention is zero, as any leakage of the coolant will cause the motor to malfunction.

[0056] Furthermore, the carbon fiber, glass fiber, and / or polymer composites of the present invention do not induce magnetic losses in the motor. More specifically, glass fibers (e.g., S2 glass) are excellent electrical insulators, just like polymers, and do not induce electrical losses in the motor. Carbon fibers are electrically conductive along the length of the fiber (approximately 2 to 20 micro-ohm-meters). However, the continuous carbon fiber composites used in the present invention are insulated from each other by the polymer matrix, resulting in an electrically conductive path free of eddy current losses.

[0057] The present invention relates to innovative materials and manufacturing methods to improve existing stator sleeves. The basic approach is to use advanced thermoplastic composite materials along with innovative manufacturing methods to manufacture improved stator structures.

[0058] The general approach of the present invention is to first manufacture the pipe body using a process such as automated fiber placement (AFP) (which may be in-situ consolidation (ISC)) to produce the structure for the cylindrical sleeve. Any additional features such as end fittings and / or axial structure may then be incorporated.

[0059] The present invention begins with the production of a composite sleeve. Continuous fiber reinforcements, such as S2 glass, IM7 carbon, boron, or any other suitable fiber, can be used. Continuous fibers with higher strength and stiffness are preferred. A polymer matrix is used to maintain the fiber's position in the stator sleeve, protect the fibers, transfer structural loads between the fibers, and prevent coolant penetration. Thermoplastic polymers are preferred due to their ability to thermally combine with other features, coolant resistance, and recyclability. Depending on the operating temperature and other factors, suitable polymers include, but are not limited to, PA, PET, PBT, POM, PPS, PEEK, PAEK, and PEKK.

[0060] Figure 2A This is a picture of the in-situ consolidation (ISC) process. Figure 2B is with Figure 2A , showing the in situ consolidation process. An incoming prepreg tape 20 is first directed between one or more tape supply rollers 21. The prepreg tape is ultimately laid down onto a tool 22, on which a plurality of layers 23 are arranged. As the prepreg tape is directed past the supply rollers, it is ultimately directed onto the tool or the previous layer by rollers 24, which apply a force 25 to urge the prepreg tape onto the tool or the previous layer. The direction of travel is indicated by arrows 26. This means that either the tool moves in one direction or the rollers move in the other direction, or a combination of the two. A hot gas torch convection heater 27 is used to heat the prepreg tape 20. Once a sufficient number of layers have been laid down, the prepreg tape can be severed by a tape cutter 28.

[0061] Using existing technologies for AFP and ISC, composite sleeves are manufactured using reinforced thermoplastic composites (such as, but not limited to, S2 / PEEK). To achieve high compressive strength, unidirectional composite prepreg tapes and a predominantly hoop-wound orientation are preferred. This means that the continuous length of fiber is circumferentially around the sleeve. Figure 2A The ISC process is shown, which makes a barrel, Figure 2B A diagram of the process is shown in . The diagram shows a hot gas torch (HGT) heating technique, however lasers, flash lamps, infrared (IR) heaters or other suitable heating methods may also be used.

[0062] After the composite sleeve has been solidified, it is removed from the mandrel and trimmed to the desired length. The mandrel can be cooled to facilitate removal of the composite sleeve from the mandrel, and such cooling can be integrated into the mandrel using, for example, a refrigerant. It is worth noting that ISC processing generally does not require a release agent, unlike consolidation where the mandrel is heated together with the part in an autoclave. The mandrel never reaches the polymer melting temperature, thus preventing bonding. In the inventors' experience, inexpensive aluminum mandrels are preferred due to their high coefficient of thermal expansion (CTE), which facilitates removal of the part after cooling.

[0063] Figure 3 FIG. 1 is an embodiment of a cylindrical unfinished stator sleeve 18 removed from a cylindrical mandrel as an example of a tool 22 .

[0064] Similarly, a disintegrating or soluble mandrel can be used. A disintegrating or soluble mandrel can be used, but is generally not required for the ISC process. In cases where removal is not otherwise possible, PLA (polylactic acid), eutectic salts, or any other suitable soluble mandrel can be used.

[0065] Alternatively, an unconsolidated sleeve preform can be made using braiding, 3D braiding, knitting, or other textile processes. The sleeve preform can be consolidated using vacuum bags, shrink wrap, or other suitable methods rather than ISC. However, braiding or other textile weaving processes can reduce the compressive strength of the composite sleeve due to the fiber fluctuations necessitating thicker laminates.

[0066] Figure 4A A slotted compacting roller 30 is shown. The slotted compacting roller is used to form axial ribs 40. The slotted compacting roller rolls along the longitudinal direction of the unfinished stator sleeve 18, with a curvature 31 matching the sleeve's outer diameter. An annular gap 32 is present, forming the axial ribs 40. In other words, the axial ribs 40 on the outer diameter of the unfinished stator sleeve 18 are formed using an in-situ process, where a neat polymer is melted onto the sleeve's outer diameter, and the roller forms a square cross-sectional profile using the annular gap 32. Heat is applied to the neat material and the stator sleeve's outer diameter to melt-bond them. The roller also applies the necessary compaction force to push the neat material onto the sleeve, achieving intimate contact and molecular chain entanglement.

[0067] Figure 4B It is shown that axial features 40 (eg, stator slots) can be added using grooved or otherwise shaped recesses in the compaction rollers in combination with additional composite or polymer filaments using an ISC process.

[0068] Alternatively, features can be added using an additive manufacturing process such as fused filament fabrication (FFF). These features can be added using continuous fiber composites, chopped fiber fill, or pure polymer filaments.

[0069] Additionally, the stator slots can be filled with an insulator (e.g., a PEEK polymer insert) for electrical insulation. Such slot fillers can advantageously be incorporated into the stator sleeve for the added benefit of greater bending stiffness.

[0070] A trimming operation may be required to trim each end of the unfinished stator sleeve 18 , resulting in a trimmed stator sleeve having a first end 18 a and an opposing second end 18 b .

[0071] To complete the production of a ready-made stator sleeve, the ends of the stator must be configured to work within a specific motor. This means that various features and structures are required along the ends of the stator sleeve. In the present invention, end rings or other features can be added by fusion bonding or other methods. Figure 5A and Figure 5B Two schematic end rings 51 and 52 are shown which may be attached to the stator sleeve.

[0072] Figure 6A is an enlarged cross-sectional view showing Figure 5A The structure (end ring 51) is attached to one end 18a of the unfinished stator sleeve 18. Similarly, Figure 6B It is also an enlarged cross-sectional view showing Figure 5B The structure (end ring 52) is attached to the other end 18b of the unfinished stator sleeve 18. The overlap of the unfinished stator sleeve 18 and the end fitting can be seen.

[0073] Figure 7 The use of a cylindrical fixture 60 to position the end rings 51, 52 relative to the unfinished stator sleeve 18 is now shown. The fixture helps align and maintain the end rings in position relative to the stator sleeve. For example, the cylindrical fixture 60 has a larger diameter portion 61 that abuts against the end ring 51 when the end ring 51 is first slid on. Next, the stator sleeve can be slid on. Finally, the end ring 52 can be slid onto the cylindrical fixture 60. In this way, all three components are held together in an abutting relationship. Subsequently, as shown, a laser welder 70 or other equipment can be used to bond the end rings to the sleeve.

[0074] Figure 8 yes Figure 7 , laser energy 71 is now applied to the end fitting and stator sleeve using a laser welding machine 70. It can be seen that the laser energy 71 is applied to the unfinished stator sleeve 18 and end ring 52 and permanently connects them together.

[0075] Figure 9 Shown as Figure 8 A side view of laser welding of an end fitting is shown in FIG. Laser beam 71 is shown directed toward the end fitting and roller 72. Roller 72 helps facilitate the connection of the end ring to the stator sleeve. The roller applies compacting pressure to the sleeve and end ring. Heat and pressure are applied to melt the plastic material together. The laser energy melts the surface, and the roller applies the pressure necessary to bond the two components together. Those skilled in the art will appreciate that other techniques, such as melt bonding or friction welding, can also be used to permanently connect the end ring to the stator sleeve.

[0076] exist Figure 8 and Figure 9In the example, the stator sleeve typically has a tan color, representing the natural color of the S2 / PEEK composite, while the end fittings are darker (e.g., black), indicating that the PEEK is filled with an IR-absorbing material (e.g., carbon black). S2 / PEEK is transparent to IR lasers, while the carbon black-filled PEEK absorbs the IR laser energy, thereby heating the carbon black-filled PEEK surface and enabling it to melt-bond to the S2 / PEEK sleeve.

[0077] Figure 10 The finished stator sleeve 16 is shown. One advantage of the present invention is that the polymer used to make the end rings and the polymer used in the polymer matrix of the prepreg tape can be the same material. This allows for a good connection between the stator sleeve and the end rings, whether they are laser welded or fusion bonded.

[0078] Figure 11 An alternative form of manufacturing the stator sleeve of the present invention using pocket molding is shown.

[0079] The bladder is formed as an alternative consolidation method. The idea is to start with a composite sleeve 80 that does not need to be fully consolidated. Such a sleeve can be, for example, a partial ISC (in situ consolidated) sleeve or a braided sleeve.

[0080] The manufacturing process may include the following steps. First, a composite sleeve 80 is manufactured. Step A shows the insertion of a deformable bladder 81 into the composite sleeve 80. The composite sleeve and bladder are then inserted into a bottom mold 82 and a top mold 83. Step B shows pressurizing the bladder 84 to force the sleeve to take the shape of the bottom mold 82 and the top mold 83. Step C shows heating the assembly 85 to above the melting temperature of the polymer. This heating will occur while pressurizing. The assembly is then cooled 86 and the consolidated part and bladder are removed from the mold as shown in step D. Although Figure 11 The shape is a simple cavity for illustration only, but those skilled in the art will appreciate that the shape may be a cylinder or any other shape.

[0081] Figure 12-16 is a better description Figure 11 A perspective view of the process described in . Figure 12 82 and top mold 83. It is a two-part mold, but can include any number of parts and sections. The inside of the mold defines a surface 87, which will ultimately define the outer surface of the stator sleeve 16 after pressurization and heating. Figure 13 The addition of a composite sleeve 80 and the insertion of a deformable bladder 81 within the composite sleeve 80 are shown. Figure 14 The top mold 83 is shown added, and then the deformable bladder 81 is pressurized 84 and heated 85. After sufficient time to complete the formation of the sleeve, Figure 15It is shown that the assembly can be cooled 86 and the bladder 81 can be depressurized. Figure 16 It is shown that the top mold 83 can be removed and then the bladder 81 can be removed. The composite sleeve 80 can then be removed. It should be understood that the composite sleeve 80 can then be trimmed and end rings added as previously described.

[0082] This approach offers several advantages, which will now be described. The internal pressure and resulting expansion tend to remove wrinkles from the fibers, thereby increasing compressive and tensile strength. The process fully consolidates the laminate, reducing porosity and eliminating infiltration. External features such as ribs, end rings, or other features can be formed, provided there is excess polymer or filler polymer.

[0083] Depending on temperature, expansion, and other factors, the bladder can be made of different materials. The bladder can be made of an elastomer (such as silicone), a metal (such as aluminum), or a polymer with a higher melting point (such as polyimide).

[0084] The bladder can be energized in a variety of ways. First, it can be energized by internal pressure (e.g., through pneumatics or air pressure). Second, it can be energized by applying force (through the use of various structures, clamps, and / or weights). Third, it can be energized by utilizing a material with a higher coefficient of thermal expansion (CTE) than the surrounding structure.

[0085] For example, an air-pressurized silicone bladder can be used to bag mold a fiberglass / PA composite sleeve. Alternatively, a solid silicone cylinder can be used instead of the bladder, where the high CTE of the silicone (assuming the mold has a lower CTE, such as steel) will apply pressure at the melting temperature of the PA. In the case of a fiberglass / PEEK cylinder, the silicone bladder will degrade at the higher temperatures (>343°C) required to melt PEEK, so a higher temperature bladder such as a PI bladder or an aluminum bladder is required. Alternatively, a solid aluminum cylinder can be used instead of the bladder, where the high CTE of the aluminum (assuming the mold has a lower CTE, such as steel) will apply pressure at the melting temperature of the PEEK.

[0086] Although several embodiments have been described in detail for purposes of illustration, various modifications may be made to each embodiment without departing from the scope and spirit of the invention. Accordingly, the invention is not to be restricted except as in the appended claims.

[0087] Reference Signs List

[0088] 10 motors

[0089] 11 Shell

[0090] 12 stator

[0091] 13 windings

[0092] 14 rotors

[0093] 15 rotor sleeve

[0094] 16 stator sleeve

[0095] 17 permanent magnets

[0096] 18Unfinished stator sleeve

[0097] 20 prepreg tape

[0098] 21 belt supply roller

[0099] 22 Tools, mandrels

[0100] 23 floors, multiple floors

[0101] 24 rollers

[0102] 25 strength

[0103] 26 Direction of travel

[0104] 27 heater, hot air torch convection heater

[0105] 28 with cutter

[0106] 30 slotted compaction roller

[0107] 31 curvature

[0108] 32 annular gap

[0109] 40 axial features / ribs

[0110] 51 end ring

[0111] 52 end ring

[0112] 60 cylindrical fixing tool

[0113] 70 laser welding machine

[0114] 71 laser energy

[0115] 72 rollers

[0116] 80 composite sleeve

[0117] 81 deformable bladder

[0118] 82 bottom mold

[0119] 83 top mold

[0120] 84 pressurization

[0121] 85 Heating

[0122] 86 Cooling

[0123] 87 surface

Claims

1. A method of manufacturing a stator sleeve, the stator sleeve being configured to be assembled as part of a cooled electric machine having a stator and a rotor, the stator having a stationary conductor with a winding, the rotor having rotating permanent magnets, wherein a coolant liquid is configured to cool the stationary conductor with the winding, the method comprising the steps of: providing a cylindrical mandrel; wrapping the cylindrical mandrel with prepreg tape using automated fiber placement with in-situ consolidation; wherein the prepreg tape comprises a continuous fiber reinforcement within a polymer matrix; heating prepreg tapes during automated fiber placement; Cooling the wound prepreg tape by waiting for the elapsed time; removing the cylindrical mandrel from the wound prepreg tape to obtain a cylindrical unfinished stator sleeve; trimming each end of the unfinished stator sleeve to obtain a trimmed stator sleeve, the trimmed stator sleeve having a first end and an opposite second end; providing a first end ring and a second end ring, wherein the first end ring and the second end ring each comprise a polymer; wherein the polymer of the first end ring and the second end ring is the same material as the polymer matrix of the prepreg; Using a cylindrical fixing tool, a first end ring and a second end ring are respectively pressed against the first end and the second end of the trimmed stator sleeve; and The first and second end rings are laser welded or fusion bonded to the first and second ends of the trimmed stator sleeve, respectively, to form a completed stator sleeve for installation in a cooled electric machine.

2. The method according to claim 1, wherein The prepreg tape is wound in a hoop-wound orientation.

3. The method according to claim 1 or 2, wherein The continuous fiber reinforcement material includes S2 glass, IM7 carbon or boron.

4. The method according to claim 1 or 2, wherein: The polymer matrix includes PA, PET, PBT, POM, PPS, PEEK, PAEK or PEKK.

5. The method according to claim 1 or 2, wherein: Heating of the prepreg tape during the automated fiber placement includes hot air torch convection heating, laser heating, flash lamp heating, or infrared heating.

6. The method according to claim 1 or 2, wherein: The first end ring and the second end ring include a carbon black filled polymer.

7. The method according to claim 1 or 2, wherein: The stator sleeve is impermeable to the coolant liquid.

8. The method according to claim 1 or 2, wherein: The prepreg tape is unidirectional.

9. The method according to claim 1 or 2, wherein: The step of removing the cylindrical mandrel from the wrapped prepreg tape includes cooling the cylindrical mandrel to cause it to shrink and reduce in size.

10. The method according to claim 9, wherein: Cooling the cylindrical mandrel includes flowing a cooling liquid through the cylindrical mandrel.

11. The method according to claim 1 or 2, wherein: The step of removing the cylindrical mandrel from the wound prepreg tape includes dissolving the cylindrical mandrel in a liquid configured to dissolve a material of the cylindrical mandrel.

12. The method according to claim 1 or 2, wherein: The step of removing the cylindrical mandrel from the wound prepreg tape includes disintegrating the cylindrical mandrel.

13. A method of manufacturing a stator sleeve, the stator sleeve being configured to be assembled as part of a cooled electric machine having a stator and a rotor, the stator having a stationary conductor with a winding, the rotor having rotating permanent magnets, wherein a coolant liquid is configured to cool the stationary conductor with the winding, the method comprising the steps of: providing a cylindrical mandrel; wrapping the cylindrical mandrel with prepreg tape using automated fiber placement; wherein the prepreg tape comprises a continuous fiber reinforcement within a polymer matrix; heating prepreg tapes during automated fiber placement; Cooling the wound prepreg tape by waiting for the elapsed time; removing the cylindrical mandrel from the wound prepreg tape to obtain a cylindrical, incompletely consolidated, unfinished stator sleeve; providing an outer mold defining an outer surface of a finished stator sleeve; placing an incompletely consolidated, unfinished stator sleeve in the outer mold as a composite sleeve; inserting the deformable bladder into the composite sleeve; pressurizing the deformable bladder; heating an assembly comprising the outer mold, the incompletely consolidated unfinished stator sleeve, and the deformable bladder to obtain a fully consolidated unfinished stator sleeve; cooling the assembly; removing the fully consolidated unfinished stator sleeve from the outer mold and removing the deformable bladder; trimming each end of the fully consolidated unfinished stator sleeve to produce a trimmed stator sleeve having a first end and an opposite second end; providing a first end ring and a second end ring, wherein the first end ring and the second end ring each comprise a polymer; wherein the polymer of the first end ring and the second end ring is the same material as the polymer matrix of the prepreg; Using a cylindrical fixing tool, a first end ring and a second end ring are respectively pressed against the first end and the second end of the trimmed stator sleeve; as well as The first and second end rings are laser welded or fusion bonded to the first and second ends of the trimmed stator sleeve, respectively, to form a completed stator sleeve for installation in a cooled electric machine.

14. The method according to claim 13, wherein The prepreg tape is wound in a hoop-wound orientation.

15. The method according to claim 13 or 14, wherein: The continuous fiber reinforcement material includes S2 glass, IM7 carbon or boron.

16. The method according to claim 13 or 14, wherein: The polymer matrix includes PA, PET, PBT, POM, PPS, PEEK, PAEK or PEKK.

17. The method according to claim 13 or 14, wherein: Heating of the prepreg tape during the automated fiber placement includes hot air torch convection heating, laser heating, flash lamp heating, or infrared heating.

18. The method according to claim 13 or 14, wherein The first end ring and the second end ring include a carbon black filled polymer.

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