STATOR FOR ELECTRIC MOTOR

Abstract

The invention relates to a stator for an electric motor, including at least one winding of a wire made of an electrical conductor composed primarily of aluminum covered with a thickness of between 30 and 100 m of an insulator including at least one polymer chosen from among the polyaryletherketones (PAEK).

Claims

1. A stator for an electric motor, the stator including at least one winding of a wire made of an electrical conductor composed primarily of aluminum covered with a thickness of between 30 and 100 m of an insulator including at least one polymer chosen from among the polyaryletherketones (PAEK).

2. The stator according to claim 1, the insulator including at least polyether ether ketone (PEEK).

3. The stator according to claim 1, the slot-fill factor of the stator being higher than 50%.

4. The stator according to claim 1, being impregnated with an epoxy resin, with a polyesterimide enamel or with a silicone.

5. The stator according to claim 1, including a sheet of an aramid-based insulator, of a fluorinated resin, in particular of PTFE, or of PEEK, around the phase windings.

6. The stator according to claim 1, the electrical conductor being composed entirely of aluminum.

7. An electric motor including a stator according to claim 1.

8. A compressor operating with ammonia as the refrigerant, including an electric motor according to claim 7.

Description

[0032] The invention will be able to be better understood upon reading the following detailed description of non-limiting exemplary implementations thereof, and upon examining the appended drawing, in which:

[0033] FIG. 1 schematically shows, in section, an example of a conductive wire according to the invention;

[0034] FIG. 2 illustrates the filling of a slot of the stator;

[0035] FIG. 3 schematically shows a motor according to the invention; and

[0036] FIG. 4 schematically shows a compressor according to the invention.

CONDUCTIVE WIRE

[0037] FIG. 1 shows an example of a conductive wire according to the invention. This conductive wire 1 includes a metal electrical conductor 2 and an insulating coating 3.

[0038] The electrical conductor is made primarily from aluminum, or is even composed exclusively of aluminum.

[0039] Its cross section may be circular or otherwise, in particular square or rectangular, which may make it possible to produce, if required, an ordered winding, having a better slot-fill factor.

[0040] The cross section of the electrical conductor ranges from 1 to 7 mm.sup.2, for example, depending on the power of the motor.

[0041] The insulating coating 3 is based on PAEK, preferably on PEEK.

[0042] The coating may be entirely composed of PEEK.

[0043] The wire may be manufactured using an extrusion process. The tolerances on the outer diameter of the insulated wire are +/15 m.

[0044] It is possible to combine, as required, PAEK with other polymers such as polyamide-imide or even polyphenylene sulfide (PPS), either alone or else combined with polyphenylsulfone (PPSU) polyolefin polyalkenes or polyethersulfone (PESU), or any other resin having a glass transition temperature (T.sub.g) that is higher than 150 C.

[0045] The coating is between 30 and 100 m, preferably between 30 and 50 m, in thickness.

[0046] Stator

[0047] The stator includes a magnetic circuit, which may be of any type, including slots within which the phase windings are accommodated.

[0048] FIG. 2 shows such a slot 5 and a portion of the conductive wires 1 accommodated within.

[0049] The number of slots depends on the polarity of the motor. The motor may be synchronous or asynchronous, but preferably synchronous. The number of poles ranges from 2 to 8, for example. The power of the motor ranges from 0.5 to 400 kW, for example.

[0050] The stator may be impregnated using a coating or impregnation epoxy resin. It may also be impregnated with polyesterimide enamel or silicone.

[0051] The slots and the phases may be insulated with sheets 6 of an insulator, for example PTFE, PEEK or aramid papers.

[0052] The conductive wires may be laced using aramid cord.

[0053] The phases may be marked using polyolefin heat-shrink tubing.

[0054] FIG. 3 shows a motor comprising a stator 83 according to the invention and a rotor 81 with poles 82.

[0055] FIG. 4 shows a compressor comprising a motor 8 according to the invention, with an inlet stage 7 and an outlet 9.

[0056] Comparative Tests

[0057] A number of tests have been carried out with an aluminum wire coated with different thicknesses of insulator.

TABLE-US-00001 TABLE 1 Breakdown voltage (kV) Insulation After aging radius Before aging from Thermal Wire (mm) from ammonia ammonia shock Abrasion Fill (%) Insulator n.sup.o1 0.407 >15 >15 OK OK 19.9 Insulator n.sup.o2 0.373 >15 >15 OK OK 25.2 Insulator n.sup.o3 0.232 >15 >15 OK OK 29.7 Insulator n.sup.o4 0.075 8 11.5 OK OK 50.1 Standard 0.040 5 0 OK OK 50-60 insulator

[0058] The insulators 1 to 4 consist of various thicknesses of PEEK.

[0059] The standard insulator consists of copper enameled with PEI (polyesterimide)/PAI (polyamide-imide). It can be seen that insulator n 4, according to the invention, retains good mechanical strength and electrical resistance after aging in contact with ammonia, as well as a good slot-fill factor, higher than 50%.