Patent ID: 12199475

In the interests of clarity, the same elements will bear the same references in the various figures.

DETAILED DESCRIPTION

FIG.1represents a cross-sectional schematic view of a rotor1of a rotating electrical machine according to the invention. The rotor1of a rotating electrical machine comprises a plurality of poles22, and preferentially four poles22, each extending on a first axis A1that is radial with respect to the rotor1, and more specifically with respect to an axis of rotation of the rotor1, and on a second axis A2parallel to the rotor1with respect to the rotor1, and more specifically with respect to the axis of rotation of the rotor1. In other words, the pole22A extends on the axis A1aand the pole22B extends on the axis A1b. Each pole22comprises a pole body220extending on the first axis A1and the second axis A2, and a rotor winding222for each pole22, positioned against the body220of the pole22. The rotor winding222takes the form of a strip extending over the length L of said pole body220on the radial first axis A1wound against the body220of the pole22. For each rotor pole, the strip envelops the body220and is wound around the body forming a superpositioning of layers of strip around the body220.

The rotor1also comprises a plurality of closure shims4. A closure shim4of the plurality of closure shims is in contact with a rotor winding222associated with a pole body220and said closure shim4is configured to exert a pressure on said rotor winding222towards said pole body220. The term “towards” means that the winding222is positioned bearing against the pole body220by the pressure action of the closure shim4. This pressure action of the closure shim4can be exerted, preferentially at right angles with respect to the length of the pole body220, that is to say at right angles with respect to the radial first axis A1or on an axis having a component on an axis at right angles to the radial first axis A1and at right angles to the second axis A2.

As stated previously, the winding222takes the form of a strip wound along the pole body220and thus using all the available volume around the body220of the pole22, unlike the wire windings according to the prior art. Consequently, a strip winding222presents the advantage of being more compact than a conductive wire winding

Indeed, the contact between two planar zones, namely two zones of the winding222of the strip, wound around one another, is perfect. By contrast, the contact between two wire zones of a wire winding according to the prior art is made only at a point of contact, then freeing up a volume that is inaccessible for the conductor and therefore inappropriate for the electrical induction.

Furthermore, as is known, heat is generated in the windings because of the ohmic losses linked to the electrical currents.

Now, the permanent contact between two layers of the strip winding222also presents the advantage of generating a perfect thermal bridge between the two layers, facilitating the thermal transfer and the extraction of heat to the outside. Conversely, the imperfect contact between the conductor wires of a winding according to the state of the art allows air, which is a thermal insulator, to occupy the volume available between each conductor wire, which is a brake to the thermal extraction from the winding according to the state of the art.

The rotor winding222is preferentially an oxidized aluminium strip. The oxidized aluminium strip presents the advantage of lightening the winding and therefore the pole22of the rotor, thus making it possible to increase the speed of rotation of the pole22. Furthermore, the oxidation of the aluminium also represents an advantage by allowing the electrical insulation between the different layers of the strip of the winding222while reducing the distance between each layer of the strip of the winding222, favouring the thermal bridge between the layers of the strip of the winding222. Indeed, the anodic oxidation of the strip makes it possible to wind with a very small thickness of the layers of insulation, approximately 8 μm, optimizing the filling of the winding by the winding222and the heat exchange.

As a variant, the rotor winding222is a copper strip. A copper strip then presents the advantage of being a better electrical conductor compared to the oxidized aluminium strip, but also presents the drawback of being heavier, limiting the rotation speed of the rotor.

As stated previously, the rotor1comprises a plurality of closure shims4. More specifically, the rotor1comprises a necessary number of closure shims4to keep each winding222against the pole body220affiliated with said winding222. Each closure shim4then has a form favouring the pressure bearing on the winding222in contact with said closure shim4against the pole body220around which the winding222is located. Consequently, the closure shim4can have a planar form extending over the length L of the pole body220and over the length of the winding222on the first axis A1and on the second axis A2.

According to a preferential variant, the rotor1has as many closure shims4as poles22. Thus, a rotor1having four poles comprises four closure shims4. Each closure shim4is in contact with two poles22that are adjacent to one another so as to induce a pressure on each winding222towards each body220of a pole22. For this, the closure shim4takes the form of a V, as represented inFIG.2, extending on two secant planes of which a first plane P1of the two planes, which extends parallel to the first axis (A1afor the pole22A) and parallel to the second axis A2, is in contact with the rotor winding222A of a first pole22A of the plurality of poles22and of which a second plane P2of the two planes, which extends also parallel to the first axis (A1bfor the contact with the pole22B) and parallel to the second axis A2, is in contact with the rotor winding222B of a second pole22B of the plurality of poles22, the second pole22B being adjacent to the first pole22A, as represented inFIG.1.

This disposition presents the advantage of reducing the number of closure shims4and therefore reducing the overall weight of the closure shims4on the rotor1.

Furthermore, any form of the closure shim4that makes it possible to induce a pressure on the windings222towards two bodies220of adjacent poles22can be taken into account. As an example, a closure shim of triangular form can be considered if two faces of the closure shim are in contact with two windings of two adjacent poles22.

Hereinafter in the description, the closure shim4is likened to a V 4.

The closure shim4is obtained in a material allowing a good conduction of heat in order to induce a good extraction of the heat from the windings222. As an indicative example, the closure shim is obtained in a metallic material.

The use of a V 4 extending on two distinct planes, the first plane P1and the second plane P2allowing a perfect contact between the winding222and one of the first plane P1or second plane P2presents the advantage of having a better cooling of the windings222because of the increased heat exchange surface compared to the potential heat exchange surface of the wires of a winding according to the state of the art.

Furthermore, the closure shim4, represented inFIG.2, comprises:an inlet aperture42positioned at a first end420of the closure shim4along the second axis A2,a first discharge aperture44A positioned at a second end440of the closure shim4along the second axis A2, different from the first end420,and a second discharge aperture44B positioned at the second end440of the closure shim4along the second axis A2, so as to allow a coolant to pass through the closure shim4from the inlet aperture42to the first discharge aperture44A or to the second discharge aperture44B and facilitate the heat exchange between the winding222and the coolant passing through the closure shim4. As an indicative example, the coolant is a heat-transfer fluid, for example oil. Nevertheless, any liquid promoting the thermal extraction and therefore having good thermal characteristics can be a coolant.

The inlet aperture42is linked to the first discharge aperture44A and to the second discharge aperture44B by a duct network48, represented inFIG.3. The duct network48, which is included in the closure shim4, therefore makes it possible to circulate the coolant in the closure shim4.

Furthermore, the inlet aperture42can be positioned randomly at the first end420of the closure shim4. Thus, the inlet aperture42is in contact with the first plane P1of the two planes. According to a variant, the inlet aperture42is in contact with the second plane P2of the two planes. According to another, preferential variant represented inFIG.2, the inlet aperture42is in contact with the two planes P1and P2. The first discharge aperture44A can be positioned randomly at the second end440and is, for its part, in contact with the first plane P1. The second discharge aperture44B can be positioned randomly at the second end440and is in contact with the second plane P2. According to a variant of the invention, the first discharge aperture44A and the second discharge aperture44B are merged at the second end440.

According to a preferential variant of the invention, the first discharge aperture44A is distinct from the second discharge aperture44B.

According to a preferential aspect of the invention, the radial distance between the rotor1and the inlet aperture42is greater than the radial distance between the rotor1and the first discharge aperture44A. Also, similarly, the radial distance between the rotor1and the inlet aperture42is greater than the radial distance between the rotor1and the second discharge aperture44B.

Furthermore, the duct network48can successively take a straight form480and a bent form482. The overall form of the duct network48can be likened to a serpentine form starting from the inlet aperture42and culminating either at the first discharge aperture44A or at the second discharge aperture44B. Furthermore, the straight form480is defined according to a slope α that is inclined with respect to the second axis A2. More specifically, the straight line defining the straight form480is secant to the second axis A2according to an angle forming the slope α. In an indicative example, the slope α is between 1° and 3°. The duct network48thus takes the form of a channel included inside the closure shim4extending between the first discharge aperture44A and the second discharge aperture44B. The succession of straight and bend and the slope of each straight thus offers the advantage of making it possible to optimize the flow of the coolant inside, so as to have a significant flow rate in the duct network48. Consequently, the thermal extraction is thereby enhanced. It is also possible to consider each straight form480being defined by a specific and different slope α so as to further optimize the flow.

Thus, the positioning of the inlet aperture42in radial proximity to the rotor coupled with the radial distance from the first discharge aperture44A and from the second discharge aperture44B, the presence of the slope α, associated with the centrifugal force due to the rotation of the rotor1, makes it possible to enhance the circulation, by increasing the flow rate, of the coolant in the closure shim4. Consequently, with a significant flow rate of the coolant in the closure shim4, this configuration makes it possible to increase the heat extraction capability of the V 4, and, particularly of the coolant passing through the closure shim4.

FIG.4represents an electrical link6between a winding222of the pole22and an electrical power source80of the rotating electrical machine. In fact, the rotor winding222of the pole22is then linked electrically to the electrical power source80via electrical links6. Generally, the electrical power source80is made of copper. Now, the winding222is, according to a variant stated previously, a strip of oxidized aluminium. And the electrical connection between a component made of copper and a component made of oxidized aluminium is relatively poor.

Consequently, in order to allow a good electrical connection between the electrical power source80and the winding222, the electrical links6are obtained by cold pressure welding, friction stir welding, pressure brazing or pressure welding. As a preferential example, cold pressure welding is the method of connection between the electrical links6and the winding222ensuring an electrical continuity between the winding222made of aluminium strip and the electrical power source80made of copper. Furthermore, this connection principle, namely the cold pressure welding, is economical. According to this connection method, the electrical power source80is brazed and then crimped with the winding222made of oxidized aluminium strip.