阅读说明：本技术 用于电动马达的定子、电动马达和包括其的压缩机 (Stator for electric motor, electric motor and compressor comprising same ) 是由 伯努瓦·珀蒂加尔 尼古拉·唐吉 安妮·希门尼斯 若埃尔·拉苏迪埃 于 2019-07-05 设计创作，主要内容包括：本发明涉及一种用于电动马达的定子、电动马达及包括其的压缩机,该定子包括电线的至少一个绕组,电线由覆盖有厚度在30μm与100μm之间的绝缘体的主要由铝构成的电导体制成,该绝缘体包括选自聚芳醚酮(PAEK)之中的至少一种聚合物。(The present invention relates to a stator for an electric motor, comprising at least one winding of an electric wire made of an electric conductor mainly consisting of aluminium covered with an insulator having a thickness between 30 and 100 μm, the insulator comprising at least one polymer chosen from Polyaryletherketones (PAEK), an electric motor and a compressor comprising the same.)

1. A stator (83) for an electric motor, said stator (83) comprising at least one winding of electric wire made of an electric conductor mainly consisting of aluminum covered with an insulator having a thickness between 30 μ ι η and 100 μ ι η, said insulator comprising at least one polymer chosen among polyaryletherketones.

2. The stator of claim 1, the insulator comprising at least polyetheretherketone.

3. A stator according to any of the preceding claims, having a slot filling factor higher than 50%.

4. A stator according to any preceding claim, impregnated with epoxy, with polyesterimide enamel or with silicone.

5. Stator according to any of the preceding claims, comprising a sheet (6) surrounding the phase windings, the sheet (6) being an aryl insulator, a fluorine-containing resin, in particular PTFE or PEEK.

6. A stator according to any preceding claim, the electrical conductor being composed entirely of aluminium.

7. An electric motor comprising a stator (83) according to any of the preceding claims.

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

Technical Field

The present invention relates to a stator for an electric motor, and more particularly, to a stator for the following motor: the motor is used for a compressor that operates with ammonia as the refrigerant. The invention also relates to an electric motor comprising the stator and a compressor comprising the electric motor.

Background

Since freon gas is a strong greenhouse gas and destroys the ozone layer, it is harmful to the environment.

To reduce these negative environmental impacts, the refrigeration industry, which heavily uses freon gas, is seeking to replace freon gas with "clean" gas, such as ammonia.

Many known devices now use ammonia as the heat transfer fluid. However, in these devices, gas never flows through the air gap of the stator/rotor of the rotating machine. In this type of plant the motor driving the elements for compressing the gas and called open compressor is located outside the compressor.

The object of the present invention is to introduce a stator/rotor assembly into a compressor. This assembly, also called semi-hermetic unit or hermetic unit, is more compact than the equipment using an open compressor. Furthermore, under certain conditions, these devices may be just as effective as those using freon gas.

Furthermore, the performance of the rotating machine depends inter alia on the electrical conductor wound around it. Copper is typically used because of its good electrical and thermal conductivity.

Application JP2004031253 describes an enamelled wire that can be used in ammonia. The enamelled wire is manufactured on the basis of an aluminium conductor and PPS insulation applied using existing methods for conventional enamelling.

Application CN103138451 discloses an ammonia-resistant motor with PPS-covered aluminum wire.

Patent US8006514 discloses a conductor covered with a fluorine-containing resin, preferably made of aluminium.

Patent US7082786 describes a refrigeration system equipped with a scroll compressor operating with ammonia. The windings of the motor driving the compressor are aluminum conductors covered with a fluorine-containing resin.

Application CN205406121 discloses a copper/aluminum/copper clad aluminum multilayer conductor insulated by a first polyesterimide connection layer, by a second polyamide-imide layer and by a third polytetrafluoroethylene layer.

Application DE102013017147a1 proposes the manufacture of screw compressors for hermetic applications using ammonia as the heat transfer fluid. Unlike the prior art based on a design using aluminum wire, the stator of the compressor is wound with copper wire. The insulation for copper occupies several hundred microns, which limits the slot fill factor and therefore the performance of the device.

A difficulty with semi-hermetic compressors operating in ammonia is finding components, in particular electrically conductive wires for the windings, that are compatible with the presence of ammonia and remain compatible with the presence of ammonia throughout the life of the compressor.

The "standard" components used in rotating machines that are not exposed to ammonia degrade very quickly in the ammonia, resulting in insulation failure in the stator and compressor stall.

Disclosure of Invention

The object of the present invention is to further improve an electric stator for a motor intended to operate while being exposed to ammonia, in particular from the point of view of electrical performance and length of service life.

The invention achieves this object by means of a stator for an electric motor comprising at least one winding of an electric wire made of an electric conductor mainly composed of aluminium covered with an insulator having a thickness between 30 μm and 100 μm, the insulator comprising at least one polymer chosen from Polyaryletherketones (PAEK).

Tests have shown that such a stator exhibits excellent ammonia resistance while providing a good slot fill factor and therefore high electrical performance. This represents several additional points of efficiency compared to stators manufactured with a large number of insulated copper conductors, such as defined in patent DE102013017147a 1.

Since aluminum is less electrically connected than copper, aluminum, while compatible with ammonia, impedes the performance of the motor and thus the compressor. The PAEK family exhibits excellent ammonia resistance, ensuring the reliability of the stator and therefore of the compressor.

The thickness of the insulation allows to maintain a high slot fill factor and thus allows to support a compact design.

In contrast to the present invention, selecting a conductor made of copper insulated by a coating of several hundred microns, such as is envisaged in application DE102013017147a1, results in the slots of the stator not being able to be filled to a high degree, with losses in the range of 20% to 50% with respect to standard filling.

The present invention thus allows the slot fill factor to approach that of standard fills.

Preferably, the insulator comprises at least one Polyaryletherketone (PAEK) and is preferably made of PEEK.

Preferably, the slot filling factor of the stator is higher than 50%. The slot fill factor is defined as the ratio of the total cross-section of the electrical conductors in the slot to the total cross-section of the slot.

The stator is preferably impregnated with epoxy, with polyesterimide enamel or with silicone.

The stator preferably comprises a sheet of aryl insulator, a fluororesin, especially PTFE or PEEK, surrounding the phase windings in the slots.

The stator may include a heat shrinkable tube made of a polyolefin material for the marker phase.

The electrical conductor bundle is preferably held in place outside the slot by aramid cords.

The term "predominantly aluminium" should be understood to mean that the aluminium content of the conductive metal material is at least 50%, preferably 80% and even more preferably 95% by weight. Preferably, the electrical conductor is entirely composed of aluminum.

Another subject of the invention is an electric motor comprising a stator according to the invention such as defined above.

A further subject of the invention is a compressor operating with ammonia as refrigerant, comprising a motor according to the invention.

The compressor is preferably a semi-hermetic piston, scroll, screw or centrifugal compressor, with ammonia being used as the heat transfer fluid in the refrigeration equipment.

Drawings

The invention will be better understood on reading the following detailed description of non-limiting exemplary embodiments of the invention and on examining the accompanying drawings, in which:

fig. 1 schematically shows an example of a wire according to the invention in cross-section;

figure 2 shows the filling of the slots of the stator;

figure 3 schematically shows a motor according to the invention; and

figure 4 schematically shows a compressor according to the invention.

Detailed Description

Conducting wire

Fig. 1 shows an example of a wire according to the invention. The wire 1 comprises a metallic electrical conductor 2 and an insulating coating 3.

The electrical conductor is mainly made of aluminium or even only aluminium.

The cross-section of the electrical conductor may be circular or other shapes, in particular square or rectangular, which may enable the manufacture of regular windings with a better slot fill factor if desired.

The cross-sectional extent of the electrical conductor is, for example, from 1mm, depending on the power of the motor²To 7mm²。

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

The coating may be composed entirely of PEEK.

The wire may be manufactured using an extrusion process. The tolerance for the outer diameter of the insulated wire is +/-15 μm.

The PAEK may be combined with other polymers such as polyamide-imide or even polyphenylene sulfide (PPS) alone or with polyphenylsulfone (PPSU), polyolefins or Polyethersulfone (PESU) or with a glass transition temperature (T) higher than 150 ℃ as desired_g) Any other resin bonding means.

The thickness of the coating is between 30 μm and 100 μm, preferably between 30 μm and 50 μm.

Stator

The stator comprises a magnetic circuit, which may be of any type, comprising slots in which the phase windings are accommodated.

Fig. 2 shows such a groove 5 and a part of the conductor 1 accommodated therein.

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

The stator may be impregnated using a coating or impregnating epoxy. The stator may also be impregnated by polyesterimide enamel or silicone.

The channels and phases may be insulated by a sheet 6 of an insulator, such as PTFE, PEEK or aramid paper.

Aramid cords may be used to tie the wires.

Polyolefin heat shrink tubing may be used to label the phases.

Fig. 3 shows a motor comprising a stator 83 according to the invention and a rotor 81 with poles 82.

Fig. 4 shows a compressor comprising a motor 8 according to the invention, the compressor having an inlet stage 7 and an outlet 9.

Comparative testing

Many tests have been performed with aluminum wires coated with insulators of different thicknesses.

TABLE 1

The insulators n1 to n4 include PEEK of different thicknesses.

Standard insulators include copper coated with PEI (polyester imide)/PAI (polyamide imide). It can be seen that the insulator n4 according to the invention maintains good mechanical strength and resistance and a good slot fill factor of above 50% after ageing in contact with ammonia.