Wound rotor or stator and method for manufacturing same

A method for manufacturing a wound rotor or stator having more than four poles, preferably a rotor, the rotor or stator having teeth provided with pole shoes. The method includes the following steps, for each pole: (a) producing a partial winding by winding at least one conductor over the portion of the tooth of this pole extending axially along this pole between the pole shoes of this pole and a plane (Pmin) at right angles to the axis of the pole and tangential to a pole shoe of an adjacent pole, (b) pushing back the duly produced partial winding towards the base of the tooth, and freeing said portion of the tooth having been used for the winding, and (c) repeating step (a) to produce another partial winding on the duly released portion of tooth.

TECHNICAL FIELD

The present invention relates to the manufacturing of a wound rotor of a rotating electrical machine. The invention also applies to the production of a tooth-wound stator.

BACKGROUND

It is known practise to produce the wound rotors of motors with four poles using a winding machine comprising an arm arranged to wind a wire over the entire height of each tooth of the rotor.

Such a winding technique, called “fly winding”, is particularly fast but reserved for machines with four poles, because, for a greater number of poles, the pole shoes of the teeth hamper the access to the teeth through their proximity.

Consequently, the rotors of machines with more than four poles are wound by using more complex techniques and the winding operation takes longer.

One example of a machine developed for winding a rotor with more than four poles is described in the U.S. Pat. No. 4,340,186.

There is a need to further improve the wound rotors and in particular simplify the manufacturing thereof and allow the winding operation to be performed at a higher rate, while obtaining a relatively high fill factor.

SUMMARY

The invention addresses this need through a method for manufacturing a wound rotor or stator having more than four poles, the rotor or stator comprising teeth provided with pole shoes, the method comprising the following steps, for each pole:

a) producing a partial winding by winding at least one conductor over the portion of the tooth of this pole extending axially along this pole between the pole shoes of this pole and a plane at right angles to the axis of the pole and tangential to a pole shoe of an adjacent pole,

b) pushing back the duly produced partial winding towards the base of the tooth, and freeing said portion of the tooth having been used for the winding, c) repeating the step a) to produce another partial winding on the duly released portion of tooth.

The invention makes it possible to continue to benefit from the advantages of the fly winding technique despite the higher polarity of the rotor or stator.

The winding of each partial winding may be performed over the entire length of said portion, which corresponds to the entire winding window, or, as a variant, over only a part of this portion. In this case, not all the width of the winding window is used.

The step b) above is relatively simple to perform in an automated manner, and also does not slow down the rotor or stator manufacturing time.

The presence of partial windings may be exploited by placing a spacer between two partial windings of one and the same pole. This spacer may help to axially block the partial windings on the tooth and may contribute to the cooling of the rotor or stator, particularly when it is passed through by at least one channel for circulation of a coolant, in particular air.

The invention makes it possible to easily produce partial windings with ordered conductors, having a good fill factor.

The invention is particularly suited to rotors or stators having six poles, but may be applied to other machines having more than four poles. The rotor or stator may be wound pole after pole. As a variant, several poles are wound simultaneously, in particular the diametrically opposing poles.

Each pole may comprise only two partial windings. That may be the case in particular for the rotors or stators with six poles, for which the gap between the pole shoes makes it possible to produce relatively high partial windings.

Two partial windings may be produced with continuity of the conductor wire between the two. In other words, the conductor wire is not cut from one partial winding to the other. It is possible to wind the first partial winding, then, without cutting the wire, wind the second partial winding.

Another subject of the invention, according to another of its aspects, is a rotor or stator of a rotating electrical machine with more than four poles, preferably obtained by the implementation of the method according to the invention, as defined above, comprising:teeth provided with pole shoes,at least two partial windings arranged in the extension of one another on each tooth.

The rotor or stator may have exactly six teeth.

The rotor or stator may comprise a spacer between the two partial windings of each pole, even, in the case of more than two partial windings per pole, between at least two partial windings of this pole, or between all the partial windings of this pole.

The abovementioned spacer is preferably passed through by at least one ventilation channel.

The partial windings are preferably linked electrically in series.

A sheet of a material with a low friction coefficient may be interposed between the partial windings and the corresponding tooth. Such a sheet may facilitate the sliding of the partial winding when it is pushed back towards the base of the tooth during the manufacturing of the rotor or stator according to the method defined above.

Each pole may have exactly two partial windings, but the invention also encompasses variants with more than two partial windings per pole.

DETAILED DESCRIPTION

The rotor1according to the invention represented in the figures comprises a magnetic core10, called armature, which may be formed by a bundle of superposed magnetic plates.

This magnetic core10comprises teeth11linked at their base by an annular part12provided with a central aperture13for mounting a shaft, which is not represented.

In the example considered, the rotor1has six poles and comprises six teeth11.

Ventilation channels14may be produced between the teeth11, as illustrated. These channels14may be formed between the annular part12and a partition16oriented at right angles to the longitudinal axis X of the adjoining tooth11.

In the example illustrated, each tooth11has, at its base, two channels14on each side, it being understood that other arrangements are possible, without ventilation channels, or with a different number of channels.

Each tooth11has, at its radially outermost end, two pole shoes17, also called pole tips.

The radially outer edge18of each tooth is preferably circular, centred on the axis of rotation of the rotor. The radially inner faces19of the pole shoes17are preferably, as illustrated, at right angles to the longitudinal axis X of the corresponding tooth11.

Each tooth11bears a pole winding20formed by two partial windings20aand20blinked electrically in series and linked electrically to the other poles, generally in series, or, as a variant, with two parallel channels, and in this case, preferentially in series with the poles of the same name.

The radially innermost winding20abears on the partitions16situated at the base of the corresponding tooth11.

The radially outermost winding20bbears on the faces19of the pole shoes17.

If necessary, a sheet of electrically insulating material, not represented, is interposed between the magnetic core and each partial winding.

Spacers25may be inserted, as illustrated, between the partial windings20aand20bof one and the same pole, to hold the windings20aand20bin place.

These spacers25are preferably produced in a material that is a good conductor of heat such as aluminium and are passed through by at least one ventilation channel, for example two channels26as illustrated.

Heat sinks30with fins may be fixed against the partial windings20aand20bin the inter-pole space31, as illustrated.

These sinks30may bear by their radially outermost longitudinal edge against the face19of the adjacent pole shoe17, and extend radially inwards substantially to the adjacent partition16.

The fins of the sinks30may be of variable height so that the interval formed between two sinks30housed in one and the same inter-pole space31is substantially of constant width, as illustrated.

The method for manufacturing the rotor1will now be described with reference toFIGS. 5A to 5D.

FIG. 5Ashows, by planes Pmaxand Pmin, the gap available for the winding of the tooth by winding at least one conductor wire around the tooth. This gap axially delimits a portion32of the tooth11which will be used for the winding of the first partial winding20a.

To produce this winding, the so-called “fly winding” technique may be used, consisting in employing a mobile arm rotating around the tooth.

A slip sheet33, for example made of PTFE, may be arranged around the tooth11, if necessary, as illustrated inFIG. 5A. This sheet is not represented in the other figures.

FIG. 5Bshows the tooth11after the production of the first partial winding20a, between the planes Pmaxand Pmin. This first partial winding20amay have an ordered winding, with a conductor wire of circular or non-circular section, for example square or rectangular.

Once the partial winding20ahas been produced, it is moved along the tooth11towards the base thereof, until it abuts against the partition16.

This movement may be effected for example using an element introduced before the winding under the pole shoe17or using a jaw which grasps the partial winding and drives it towards the base of the tooth.

Once the partial winding20ais at the bottom of the notch, as illustrated inFIG. 5C, it is possible to proceed with the winding of the second partial winding20bat the same point on the tooth11as the first partial winding20a, as illustrated inFIG. 5D.

Next, the spacer or spacers25may be put in place, followed by the sinks30, to obtain the arrangement illustrated inFIG. 3.

The number of turns of a partial winding ranges for example from 10 to 200. The copper diameter of the wire ranges for example from 0.315 mm to 1.6 mm. Obviously, the invention is not limited to the example illustrated.

What has just been described with reference to the figures applies to the winding of a stator armature.

Moreover, it is possible to arrange more than two partial windings on each tooth, or to give the core other forms, with, for example, pole shoes having different dimensions from one tooth to another.

It is possible to produce the partial windings over a height less than the width of the winding window given by the planes Pmaxand Pmin, for example because the inner face19of the pole shoes is no longer planar and at right angles to the radial axis X of the tooth but concave towards the axis of rotation, so as to form, for example, cooling channels, or, if so desired, several inter-winding channels.

The partial windings may be of unequal heights, if necessary, in the case of stators in particular.

The teeth may be given a helical form, to reduce torque ripples.