PRODUCTION METHOD

The present invention relates to a coil body for assembly on a magnet core of a rotating electrical machine, and a magneto-electric angle sensor, in particular a reluctance resolver, whose stator is constructed in accordance with the principles according to the invention. Finally, the present invention relates to a production method for producing such a reluctance resolver.

Such reluctance resolvers have a rotationally symmetrical, at least partially magnetically soft stator and a rotationally symmetrical, at least partially magnetically soft rotor which are located opposite each other, with an air gap being formed. The magnetic resistance in the air gap changes periodically owing to a shape of the rotor which varies over the periphery.

The angle sensor has a magnetic flux transmitter which is arranged on the stator and which produces over at least one pole pair a predetermined magnetic flux distribution in the air gap. There is further arranged on the stator a magnetic flux receiver which measures the intensity of the magnetic field over at least two signal pole pairs which are arranged offset at an angle with respect to each other, an angle value for a relative position of the rotor with respect to the stator being able to be derived from the two receiver signals.

Such angle sensors which are based on the principle of a changing magnetic flux intensity in the air gap between the stator and rotor are known in many varieties. In principle, various principles for producing the magnetic loading in the transmission portion and also various principles for measuring the magnetic field in the receiver portion may be considered in this instance. In resolver systems, that is to say, resolvers and synchros, electromagnetic coils in the form of primary and secondary windings are used. Such resolver systems in the form of resolvers and synchros have been known for some time as precise and robust angle sensors. There are also known so-called passive reluctance resolvers, in which both the primary winding and the secondary winding are accommodated on the stator, while the rotor influences the magnetic flux circuit without any winding, that is to say, passively, only with magnetically soft components. Owing to a non-uniform shape of the magnetically soft rotor, for example, by providing lobes, the magnetic flux between the primary windings and the secondary windings in the stator is influenced in a different manner, from which the angular position of the rotor can be derived via the induced voltage. In order to produce such a stator, there are different technical construction possibilities. Firstly, the windings can be wound directly on one tooth or over a plurality of teeth of the magnet core. Secondly, it is possible for winding diagrams in which only a single tooth is surrounded by the winding(s) to apply the windings only to plastics coil bodies and to fit those coil bodies to the teeth of the magnet core during assembly. Such an arrangement is known, for example, from US 5,300,884. However, this arrangement does not have any mechanical fixing capability regarding the manner in which the coil bodies could be secured to the magnet core, until the definitive fixing member is mounted, for example, via the printed circuit board, which brings about the wiring arrangement. A similar arrangement is also known from DE 10 2009 061 032 A1 .

It is further known to fix the coil bodies to the magnet core by means of special retention structures, as set out, for example, in DE 10 2010 004 887 A1 .

However, the above-mentioned known coil bodies are only wound and subsequently mounted on the magnet core in a direction along the longitudinal axis of the individual teeth. Subsequently, electrical contacting of the separated individual connections of the coils must be brought about, for example, via a printed circuit board (PCB). This approach requires a large number of individual components and a high level of complexity during assembly and contacting.

On the other hand, it is known from US 7,385,323 B2 that the coil windings can also be fitted to the coil body only when the coil body is already mounted on the magnet core. In the arrangement from US 7,385,323 B2, for example, the metal magnet core is initially surrounded by two half-shells of plastics material and the winding is subsequently fitted. The coil wire is then wound onto the insulator half-shells and through the slots which are formed at each side of the magnet pole teeth so that a large number of coils are produced in a circular series arrangement. The upper and the lower insulator half-shell cooperate with each other in order to fix the coil bodies to the magnet core.

However, a disadvantage in this arrangement is that a comparatively large number of individual plastics components are still necessary in order to provide the magnet core provided with coils.

Another significant aspect in the production of magnet cores in which the winding is wound directly on the teeth of the core is the guiding of the coil wire during the winding operation. There are various approaches to carrying out this winding as efficiently as possible. For example, US 6,685,127 B2 sets out a method for winding a rotor for an induction machine in which a hook which belongs to the winding machine is used in order to guide the wire and to prevent the winding nozzle from having to be moved in terms of its orientation in space, that is to say, from the vertical into the horizontal.

However, there is still the need to fix coil bodies to the teeth of a magnet core in such a manner that they can be mounted in a simple and cost-effective manner but ensure a reliable arrangement which is stable over time during operation, and further to allow a particularly efficient and precise winding operation.

This object is achieved by the subject-matter of the independent claims. The dependent claims relate to advantageous developments of the present invention.

The present invention is based on the notion of constructing the winding body so as to have a partially open cross-section so that the coil body can be fitted to the tooth in a direction transverse relative to a longitudinal axis of the tooth and is fixed to the tooth so as to cooperate with the tooth. In this manner, on the one hand, only a single plastics component is required for the coil body and, on the other hand, particularly efficient assembly which can readily be automated is possible.

The inventors of the present invention have recognised that the substantially saddle-like construction of the coil body is sufficient for adequate guiding, securing and insulation of the coil winding and that a completely closed cross-section is not necessary. In a particularly simple manner, the coil body is fixed to the magnet core in that a snap-fit hook or a crimping rib via which the coil body is securely fixed to the tooth is provided on the receiving member of the coil body, in which receiving member the tooth is received. Unlike known solutions, therefore, only one half-shell is provided in the solution according to the invention instead of the two-part formation otherwise conventional.

Alternatively or additionally, there may also be provided a fixing device which is arranged in a region of the coil body orientated towards the yoke of the magnet core and which cooperates with a retention structure of the magnet core in order to fix the coil body. These may be, for example, hooks which are fitted into corresponding openings in the magnet core. Such connections can be constructed, for example, in accordance with the principles of DE 10 2010 004 887 A1 .

Another aspect of the present invention is the provision of a specially constructed guide element for guiding the coil wire during the winding operation. In particular, the guide element has an inclined guiding member which extends from a front region of the guide element as far as a base region of the guide element arranged on the coil body. In particular, the guide element is constructed in such a manner that the base region has a smaller cross-section dimension than the front region. This may be achieved by a truncated pyramid-like construction of the guide element, the base face of the truncated pyramid being located in the front region and having a polygonal, circular or ellipsoid shape. However, the guide element may also be in the form of an oblique prism or an oblique cylinder, that is to say, have a cross-section which is offset in relation to the front region in the direction towards the desired wire position in the base region, but with the front region having a similar planar dimension to that of the base region.

In any case, the decisive aspect is that, by the wire being pulled, it is subjected to a force component in the direction towards the base region and is thus automatically brought into the correct position.

According to an advantageous development of the present invention, there may further be provision for the wound wire to be pre-treated in such a manner that it can be bonded after the winding operation, and consequently the casting steps which are otherwise conventional are unnecessary. For example, the wire may be provided with a corresponding coating which is melted after the winding operation by hot air in an oven or by being heated by a current flow through the wire. In this manner, the production of the coil bodies according to the invention and the associated magnet cores and sensor systems can be further simplified.

For a better understanding of the present invention, it is explained in greater detail with reference to the embodiments illustrated in the following Figures. Identical components are referred to using identical reference numerals and identical component designations. Furthermore, individual features or combinations of features from the embodiments shown and described may also constitute inventive solutions which are independent per se or solutions according to the invention. In the drawings:

Figure 1 is a perspective view of a completely assembled magnet core according to the present invention;

Figure 2 shows a detail from Figure 1 ;

Figure 3 is a perspective view of a coil body array during the assembly on the magnet core; Figure 4 shows a detail from Figure 3;

Figure 5 shows another detail from Figure 3;

Figure 6 shows a magnet core before the winding;

Figure 7 shows a magnet core after the winding;

Figure 8 is a view of the magnet core from Figure 6 rotated through 180 ^Q ;

Figure 9 is a side view of the magnet core from Figure 1 .

Advantageous embodiments of the present invention are explained in greater detail below with reference to the Figures. It should be emphasised that, although a magnet core which can be used as a stator in a reluctance resolver is always taken as a basis below, the present invention may naturally be applied to any type of rotating electrical machines. This means that the method for fixing coil members according to the invention may also be used for motors and generators, both in stator cores and in rotor cores.

Furthermore, the present invention is not limited to embodiments in which the teeth of the magnet core project inwards from an annular yoke back in the direction of the centre axis but instead, in a correspondingly similar manner, magnet core teeth which are arranged at the outer periphery of a core may also be provided accordingly with the coil bodies according to the invention.

Finally, the coil bodies according to the invention may be combined not only with laminated magnet cores, but also with magnet cores which are produced integrally.

Figure 1 is a perspective view of a magnet core 1 18 according to the invention.

In the embodiment shown, the magnet core 1 18 has a total of sixteen teeth 1 16, as proposed, for example, according to DE 10 2009 061 032 A in order to produce sixteen-pole stators for a six-speed resolver. The individual teeth 1 16 are connected to each other by means of a yoke back 132. A retention opening 120, in which a corresponding projection 1 14 engages with the coil body, is provided at both sides of the tooth 1 16 in the transition region between the yoke back 132 and the tooth 1 16 so that the coil body 100 is securely fixed to the tooth 1 16. According to the present invention, each coil body 100 is formed in such a manner that it can be fitted in a direction transverse relative to the longitudinal axis of the tooth 1 16 before the winding 1 10 is fitted. The assembly direction is marked with the arrow 122 in Figure 1 .

According to a special embodiment which is illustrated in Figure 1 , the individual coil bodies 100 are connected to each other to form an integral coil body array 140 which is substantially annular in accordance with the shape of the magnet core 1 18. Consequently, all sixteen coil bodies 100 can be mounted on the magnet core 1 18 substantially simultaneously. However, the principles of the present invention are not necessarily limited to this annular configuration of a coil body array.

As will be appreciated more clearly from the following drawings, each of the coil bodies 100 is constructed in such a manner that it cooperates directly with the magnet core, in particular with the teeth 1 16, in order to fix the coil body thereto. Therefore, no additional components are necessary for fixing the coil bodies and the actual assembly of the insulator is finished with a pressing step in the direction 122. For example, crimping ribs or catch devices may be provided at an inner face of the winding bodies 102 in order to fix the coil bodies 100.

According to another aspect of the present invention, each coil body has, for example, two guide elements 134 which guide the wire 1 1 1 to the next coil during the winding operation in the case of a changing operation in such a manner that the winding wire nozzle of a winding device does not have to be moved out of the horizontal position thereof. The guide projections have a cross- section which tapers in the direction towards the coil so that, by tensile forces being applied to the wire 1 1 1 , the wire 1 1 1 is drawn automatically downwards in the direction towards the magnet core 1 18 along the inclined guiding member. The guide elements 134 which are substantially in the form of truncated pyramids may naturally also have a base face which is elliptical, circular or polygonal in some other manner in addition to the square base face shown in Figure 1 .

As already mentioned and not illustrated in the Figures, however, the guide element 134 may also be in the form of an oblique prism or an oblique cylinder, that is to say, may have in the base region a cross-section which is offset in relation to the front region in the direction towards the desired wire position, but with the front region having a planar dimension similar to the base region. In any case, the decisive aspect is that, by the wire 1 1 1 being pulled, it is subjected to a force component in the direction towards the base region and is thus automatically moved into the correct position.

The arrangement of the windings may be brought about, for example, in accordance with the principles of DE 10 2009 061 032 A1 in that the sequence of the windings is carried out so that initially all the windings are wound in one direction (that is to say, for example, pole 16, pole 2, pole 4, etcetera, until pole 14 in the clockwise direction and subsequently poles 13, 1 1 , 9 to pole 15 in the counter-clockwise direction). It can thereby be ensured that a single large circle having the diameter of the stator is not wound but instead a large circle is initially wound in one direction and subsequently a second circle is wound in the opposite direction. For a sensor system, the winding of a single huge coil having only one winding would mean that, in this winding, the magnetic field which extends through the resolver would disrupt the signal of the resolver. In the arrangement according to the invention, the disruptive effects are advantageously averaged out.

The embodiment shown in Figure 1 further has the advantage that the wiring is formed directly by the coil wires 1 1 1 so that no additional printed circuit board (PCB) is necessary. On the one hand, this makes production easier and, on the other hand, it reduces the structural height.

Figure 2 shows a detail of Figure 1 , which particularly makes clear the operation of the guide elements 134. As can be seen in Figure 2, the guide elements 134 form inclined guiding members 126 along which the wire 1 1 1 is drawn in the direction towards the magnet core 1 18 during winding. By corresponding supply channels 108 being provided, it can further be ensured that the wires are guided towards the individual coil bodies 100 and guided away from them again in a defined manner. As is generally known, the magnet core 1 18 comprises individual plates 136.

As already mentioned, the individual coil bodies 100 may each constitute individual plastics components. In this instance, a mould seam would be at the location 128. Alternatively, however, the entire ring may also be produced on coil bodies as a single array 140 of coherent coil bodies 100.

Figures 3 to 5 illustrate an exemplary configuration of the coil bodies 100 according to the invention during assembly on the magnet core 1 18. Figures 3 and 4 show that catch projections 1 14 are provided as the retention element on the tooth 1 16 of the magnet core 1 18. Alternatively, however, crimping ribs or generally a press-fit arrangement may also be provided. Figure 5 further shows that each coil body 100 has two retention projections 1 14 which are introduced into corresponding openings 120 on the magnet core 1 18 in order to allow secure retention and positioning. The retention projections 1 14 are fixed by being pressed in the openings 120 and the configuration of the magnet core 1 18 with its openings 120 is carried out in accordance with the principles of DE 10 2010 004 887 A1 . In particular, retention structures which cooperate with the retention projections 1 14 on the coil body 100 are provided on the magnet core 1 18 in the openings 120. For example, this retention structure may be formed by two hook-like projections which engage in the retention projection 1 14.

Since the spacing between the mutually opposing retention structures of the magnet core must be relatively small in order to be able to reliably grip the plastics retention projection, a comparatively costly stamping tool must be provided if it would be desirable to provide both projections in each individual metal plate 136.

Accordingly, as explained in DE 10 2010 004 887 A1 , there is provision for each individual plate to be constructed in such a manner that, in a first and a third quadrant, the projections are orientated in one direction and, in a second and fourth quadrant, the projections are orientated in the opposite direction. By the metal sheets being laminated with a radial angular offset through 90 ^Q between two metal sheets positioned one on the other, it is mechanically possible to construct a retention structure which is compact without having to comply with those narrow structural widths when stamping a single metal plate. In order to allow simple automation of the layering operation, the individual plates constructed according to the invention may always be radially offset from position to position in the same direction, that is to say, in the clockwise direction or counter-clockwise direction.

Furthermore, the individual teeth of the magnet core may each be provided with pole shoes 138. Those pole shoes which may be formed by end regions of the tooth 1 16 which are constructed in a correspondingly broader manner, serve two different, important purposes in the arrangement according to the invention.

Firstly, the magnetic flux which flows directly from pole to pole without being directed through the rotor may be reduced by such a formation. In particular when being used in resolvers, each portion of magnetic flux which does not pass through the air gap results in a reduction of the signal strength and therefore of the precision of the resolver. For reasons relating to the drive torque and the efficiency, it is necessary in motors or generators for the magnetic flux to take the path though the air gap and via the rotor.

Secondly, such a construction with a pole shoe may also be used mechanically for fixing the coil body. To this end, it is advantageous for the coil body to taper in terms of the cross-section of the inner wall thereof so that the coil body only moves into pressing abutment with the pole shoe of the magnet core in its completely assembled position. In order to reduce the forces which occur during the fitting operation, only a small surface portion of the receiving member of the coil body should further come into contact with the pole shoe of the magnet core. To this end, additional crimping ribs may be provided on the inner wall of the coil body.

As already mentioned, the plastics pins which form the guide elements 134 are in such a form that the wire guide does not have to be pivoted during the winding in order to move from one coil to the next. The wire guide may always remain in a horizontally orientated state and the inclined guiding member 126 ensures that the wire automatically arrives in its desired final position. During the production, the wire guide moves only over the pins and is then moved and centred between the coil bodies, and subsequently the winding starts. In order to prevent disruptions during the winding, there are further provided for the wire, as already mentioned, supply channels in which the wire is arranged in order not to impede the layering action when the coil is wound.

In that manner, a disorderly winding is prevented or at least reduced and, therefore, more windings can be accommodated in a smaller space. Furthermore, the accuracy of the sensor during operation is also improved because the angular errors become greater in the case of disorderly winding.

If the wire guiding device does not have to be tilted, the entire winding process is quicker and simpler devices can also be used for the winding.

As can further be seen in Figure 5, a recess is arranged under the guide element 134, for which reason no sliding members have to be provided in the injection-moulding mould for this moulded component, and therefore the production is simplified.

Figure 6 shows the magnet core 1 18 with the coil bodies 100 mounted thereon before the coil windings are fitted.

Figure 7 is a plan view of the arrangement of Figure 1 , the individual poles for defining the winding arrangement being designated P1 to P16. The individual contact pins 1 12 directed outwards are designated C1 to C6 and an exemplary winding diagram is set out in Table 1 below. In this instance, CW signifies a winding in the clockwise direction and CCW signifies a winding in the counter-clockwise direction. Table 1 : Winding diagram, connections and winding device

Figure 8 shows an arrangement rotated through 180 ^Q . In this instance, it is also clear that each of the teeth 1 16 has a pole shoe 138.

Finally, Figure 9 is a side view of the completely assembled resolver stator 146 from Figure 1 . As can be seen from this view, all the wire connections 1 1 1 extend in the plastics material of the coil bodies. Therefore, they do not come into contact with the metal of the magnet core 1 18.

The production of a resolver stator according to the present invention is intended to be explained in detail below with reference to all the Figures 1 to 9. By way of example, it is assumed that all the coil bodies 100 are connected to each other to form a coil body array 140. For the production, the magnet core 1 18 is first constructed from a large number of layered plates 136. Subsequently, the coil body array 140 is fitted in the form of a ring over all the teeth 1 16 of the magnet core 1 18. The fixing and adjustment are carried out, on the one hand, via the retention elements 1 14 and, on the other hand, via the catch elements 130.

In the next step, the coil bodies are wound, the wire 1 1 1 being directed by means of the guide elements 134, as described above. According to an advantageous embodiment, a so-called baked enamel wire which has, for example, a polyurethane base enamel and a baked enamel which is coated thereover and which comprises polyvinyl butyral is used for the winding. After the winding, the wire may be heated by corresponding current surges or by tempering in an oven in order to bake the windings securely to each other. Alternatively, a polyamide may also be used as the baking enamel.

In this manner, the often-used injection-moulding of the windings in a separate operating step can be avoided. Furthermore, the layers of wire baked together are also arranged in a substantially more space-saving manner.

In conclusion, the arrangement according to the invention affords inter alia the following advantages both for use in reluctance resolvers and in electric motors or generators.

The coil bodies can be fixed to a magnet core in a particularly secure manner. A substantially better level of resistance to environmental influences such as vibrations and temperature variations is thereby provided. Furthermore, the coil body is centred on the stator assembly in a substantially better manner so that the electrical properties of the electrical machine are improved because all the coils take up the same position.

The magnet core provided with coils is produced substantially more quickly and in an automated manner to the greatest possible extent, the number of individual components to be supplied being reduced.

The structural height of the overall arrangement can be significantly reduced.

List of reference numerals

Reference numeral Description

100 Coil body

102 Winding body

104 First flange

106 Second flange

108 Supply channel for wire

1 10 Winding

1 1 1 Wiring arrangement

1 12 Contact pin directed outwards

1 14 Retention projection, retention element

1 16 Tooth (Pole)

1 18 Magnet core

120 Retention opening

122 Assembly direction

124 Receiving member

126 Inclined guiding member

128 Mould seam

130 Catch projection

132 Yoke back

134 Guide element

136 Plate

138 Pole shoe

140 Coil body array

146 Resolver stator

148 Recess below the guide element