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WO-2026093670-A1 - METHOD FOR PRODUCING A STATOR FOR AN AIRCRAFT ROTARY ELECTRIC MACHINE

WO2026093670A1WO 2026093670 A1WO2026093670 A1WO 2026093670A1WO-2026093670-A1

Abstract

The invention relates to a method for producing a stator for an aircraft rotary electric machine (12), from a stator body (17) delimiting a stator cavity and provided with notches (1) which extend radially in a circumferential manner, each notch (1) being delimited by a radially outer transverse wall (22c) and two side walls (22a, 22b) extending radially between the transverse wall (22c) and a radially inner opening (23) of the notch (1), a cooling circuit comprising a cooling channel (19) being arranged inside each notch (1), the method comprising inserting, into each notch (1), an insulating separator (24), a rigid sealing plug (25) and a winding comprising turns of electrical conductors (20a, 20b), as well as depositing, in each notch (1), a sealing element (26) comprising an elastomer, the rigid sealing plug (25) and the sealing element (26) forming a closure system (25, 26) intended to close the opening of the notch (1), the method further comprising depositing an inner layer (27) of composite material covering the closure system (25, 26), the method being characterised in that the deposition of the inner layer (27) of composite material is carried out by tightly fitting the inner layer (27) of composite material into the stator cavity.

Inventors

  • COURAPIED, Léonard
  • DUNLEAVY, PATRICK

Assignees

  • SAFRAN

Dates

Publication Date
20260507
Application Date
20251021
Priority Date
20241029

Claims (10)

  1. 1. A method for manufacturing a stator (13) for a rotating electrical machine of an aircraft (12), starting from a stator body (17) defining a stator cavity (31) and having slots (1) extending radially circumferentially, each slot (1) being delimited by a radially external transverse wall (22c) and two lateral walls (22a, 22b) extending radially between the transverse wall (22c) and a radially internal opening (23) of the slot (1), a cooling circuit (16) comprising a cooling channel (19) being disposed inside each slot (1) and comprising the circulation of a coolant, in particular oil, the method comprising inserting into each slot (1) an insulating separator (24), a rigid sealing plug (25), and a winding comprising windings of electrical conductors (20a, 20b), and the deposition in each notch (1) of a sealing element (26) comprising an elastomer, the rigid sealing plug (25) and the sealing element (26) forming a sealing system (25, 26) intended to seal the opening (23) of the notch (1), the method further comprising the deposition of an inner layer (27) of composite material covering the sealing system (25, 26), the method being characterized in that the deposition of the inner layer (27) of composite material is carried out by a tight fit of the inner layer (27) of composite material in the stator cavity (31).
  2. 2. Method according to claim 1, characterized in that the stator body (17) is disposed inside a holding and positioning device (30) provided with a chamfered area (30a) allowing the inner layer (27) of composite material to be guided into the inside of the stator body (17).
  3. 3. Method according to claim 1 or 2, characterized in that the composite material of the inner layer (27) of composite material comprises a thermoplastic or thermosetting resin matrix and glass fibers.
  4. 4. A method according to any one of claims 1 to 3, characterized in that the lateral walls (22a, 22b) delimiting each notch (1) comprise a radial stop capable of limiting radial displacement of the sealing plug (25) towards the interior of the stator (13)
  5. 5. A method according to any one of claims 1 to 4, characterized in that the radial stop of the side walls (22a, 22b) is constituted by a shoulder of each side wall (22a, 22b) of the notch (1), cooperating with an associated shoulder of the sealing plug (25), or by an inclined portion of the side walls having a spacing between the side walls (22a, 22b) which decreases radially towards the interior of the stator (13), and cooperating with a portion of the sealing plug (25) provided with inclined side faces (25a) and having a spacing between said side faces which decreases radially towards the interior of the stator (13).
  6. 6. A method according to any one of claims 1 to 5, characterized in that the sealing plug (25) comprises a composite material comprising a resin matrix and glass fibers.
  7. 7. A process according to claim 6, characterized in that the resin is selected from epoxy resins, phenolic resins, bismaleimide resins, polyimide resins, benzoxazine resins, phthalonitrile resins, polyaryletherketone resins, polyetherimide resins, and polyamide-imide resins.
  8. 8. A method according to any one of claims 1 to 7, characterized in that the elastomer of the sealing element (26) is selected from fluorocarbon elastomers, silicone elastomers, fluorosilicone elastomers, chloroprene, butadiene-acrylonitrile copolymers, and ethylene-propylene-diene rubbers.
  9. 9. A method according to any one of claims 1 to 8, characterized in that each notch (1) comprises a first electrical conductor (20a) located on the side of a first lateral wall (22a) and a second electrical conductor (20b) located on the side of a second lateral wall (22b), the first electrical conductor (20a) and the second electrical conductor (20b) being electrically insulated from each other using the insulating separator (24).
  10. 10. Stator (13) for a rotating electrical machine of an aircraft (12), characterized in that it is obtained by a process according to any one of claims 1 to 9.

Description

DESCRIPTION TITLE: Method for manufacturing a stator for a rotating electrical machine of an aircraft The invention relates to a method for manufacturing a stator for a rotating electrical machine of an aircraft, in particular for an aircraft electric propulsion system. It also relates to the stator obtained by the method. A rotating electrical machine, whether a motor or a generator, generally comprises a rotor configured to rotate on a shaft inside a bore of a fixed stator. Between the stator and the rotor is a narrow area called the air gap. The interaction of the magnetic fields of the stator and rotor converts electrical energy into mechanical energy in the case of a motor, or mechanical energy into electrical energy in the case of a generator. During operation, losses in the electric machine can generate large amounts of thermal energy in the stator. In high-power machines in particular, oil cooling of the stator can be preferable to air cooling. This is because oil has a higher specific heat capacity than air and therefore dissipates thermal energy from the stator more efficiently. Furthermore, oil can be used for both cooling and lubrication while being circulated by a single pump, which can help reduce aircraft weight. In some cases, electrical machines may be equipped with cooling channels formed in notches of the stator, through which oil can circulate to remove heat from the stator, as described for example in document WO 2023/152479 A1. An example of such cooling channels is illustrated in Figure 1. The notches 1 include a radially external portion 1a, in which the conductors, not shown, are housed, forming the windings stator windings and through which the oil flows. The slots 1 also include a radially internal portion housing a sealing system comprising a sealing plug 2 made of composite material, designed to contain the oil passage. Between the sealing plug 2 and the radially external portion of the slot 1 (from the top down in the figure) are arranged successively: a first adhesive layer 3, a layer of fiber/resin composite material 4 designed to absorb the pressure exerted by the oil, a second adhesive layer 5, a layer of electrical insulation 6 ensuring electrical insulation between two adjacent conductor windings within the external portion 1a, a third adhesive layer 7, and a rigid plate 8 for distributing the oil pressure forces. In addition, a layer 9 ensuring a smooth surface finish on the internal diameter of the stator is located on the inner end of the sealing plug 2. The drawback of such a solution is its complex implementation, due to the use of a draping operation involving resin-pre-impregnated fabrics in very narrow notches 1 with large radii of curvature, which leads to a risk of porosity formation 10. Such porosity or delamination can cause unwanted oil circulation, particularly towards the air gap, with a risk of fire. Furthermore, the mechanical resistance to the pressure exerted by the oil, which occurs laterally through the adhesion between the sealing plug and the edges of the notch, can be reduced in the presence of porosity, which can lead to unwanted displacement of the sealing plug 2 towards the interior of the rotating machine. A similar solution, illustrated in Figure 2, which has the same disadvantages, uses a foam or intumescent material filling plug 2. It is also known to cover the sealing system with an internal layer of composite material to ensure the geometric regularity of the stator's inner end, for example, during a co-baking step using a counter-mold to guarantee the conformity of the stator's internal diameter. This process does not allow for easy inspection, repair, and recycling of the internal composite material layer. The present invention aims to remedy these drawbacks. The invention thus relates to a method of manufacturing a stator for a rotating electrical machine of an aircraft, from a stator body delimiting a stator cavity and provided with slots which extend radially circumferentially, each slot being delimited by a radially external transverse wall and two lateral walls extending radially between the transverse wall and a radially internal opening of the slot, a cooling circuit comprising a cooling channel being disposed inside each slot and comprising the circulation of a coolant, in particular oil. The method according to the invention comprises inserting into each notch an insulating separator, a rigid sealing plug, and a winding comprising windings of electrical conductors, as well as depositing in each notch a sealing element comprising an elastomer, the rigid sealing plug and the sealing element forming a sealing system intended to close the opening of the notch, the method further comprising depositing an internal layer of composite material covering the sealing system. In the process according to the invention, the deposition of the inner layer of composite material is achieved by a tight fit (also called shrink fitting) of the inn