MXPA00000494A - Stator for an electric motor, including for a brushless direct current motor - Google Patents

Abstract

Disclosed is a stator for use in an electric motor, including a brushless direct current motor, which presents a stator body (9) provided with a number of stator teeth (3) for receiving stator coils (W1, W2, W3, W4), said stator body (9) comprising a base body (10) of magnetizable material which has an insulating layer at least in the area of the stator teeth (3) capable of receiving or having received said coils. According to the invention, the insulating layer is designed as a plastic layer connected to a base body by plastic injections, and a supporting element (13) of the stator body (9), intended for wrap type contacts (15) to which the coil ends are linked, is injected so as to form one piece with the insulating layer.

Description

STATOR FOR AN ELECTRICAL MOTOR, IN PARTICULAR FOR A BRUSHLESS CURRENT MOTOR WITHOUT BRUSHES Description of the invention The invention relates to a stator for an electric motor, in particular for a brushless DC motor, with the characteristics of the preamble of the motor. claim 1. In particular in the automotive technique there is the requirement to apply motorized drive mechanisms that can be controlled as simply as possible and manufacture with the least possible device, and therefore economical, for example for an electrically controlled hydraulic pump for a Sevodirection. By virtue of the good degree of efficiency and ease of maintenance, for the aforementioned application case particularly, brushless DC motors, in particular 4-phase DC motors, are particularly suitable. The stators known for this type of motors generally comprise a main body of a magnetizable material. Frequently the body is made of laminated sheets that are joined to each other by stacking by punching. The plates extend in planes perpendicular to the longitudinal axis of the stator.

The main body manufactured in this way already has the stator teeth on which the necessary amount of windings are applied. However, before winding the stator teeth, it is necessary to take measures to avoid that when winding the stator or otherwise, the insulation of the conductors through which the windings are formed is damaged. This risk exists in particular due to the sharp edges of the stator plates. For this reason, in the case of known stators, a powder coating is provided at least in the interior areas of the stator teeth that come into contact with the winding conductors. This layer on the one hand covers the sharp edges of the main body or of the stator plates, and on the other hand prevents an electrical contact with the main body even in the case of damage to the insulation of one or several turns. However, the disadvantage of a coating of this nature of the main body resides in the relatively costly process in time and cost. In addition, the stator windings of known motors are usually attached to contact terminals that are provided in the motor housing. Additionally, a control circuit can be provided in the housing, in which case the windings of the stator are generally connected to the terminals of the stator. contact that are provided in the control circuit, for example by welding, tightening or the like. However, this again requires independent operation stages, due to which the manufacture of such an engine becomes more expensive. Accordingly, from this state of the art the object of the invention is to create a stator for an electric motor, in particular for a brushless DC motor, which can be manufactured more simply and economically, and in particular it allows a simple contact of the stator windings. The invention solves this task with the features of claim 1. The invention is based on the knowledge that it is possible to replace by the injection of synthetic material around the teeth the powder coating of the stator teeth practiced up to now, being that it is possible to manufacture simultaneously, ie in a single manufacturing operation, a support part for the contact terminals for contact with the stator windings. This results in a substantial rationalization advantage in the production of the stator or of a corresponding motor. In the preferred embodiment of the te ^ _ ^ É _ ^^ li ^ _ ^ £ ^ _ ^^^ ¿__. invention the part of jopor e or support element is designed with respect to the axis Longitudinal stator that is provided on a front face of the stator body. The ring can be injected with recesses for the contact terminals into which then the contact terminals are inserted with their shoes, for example by pressing them. Preferably the ring comprises a radially external back extending, for example, perpendicular to the longitudinal axis of the stator. On this back the contact terminals are provided which substantially extend in the axial direction. The arrangement of the contact terminals directly on the stator itself results in the advantage that the contact terminals can serve to mechanically fix the ends of the conductors even for the winding process. In this way the last turns of the windings are prevented from slipping during the interval between the winding and the connection with the ends of the conductors, which in the case of stators or known motors happened especially when the ends of the windings Windings are connected directly to the contact terminals of a control circuit. In the preferred embodiment of the invention the ring comprises, extending from the back axially outside in a radially internal area, a wall which serves to hold and fix a control circuit attached to the stator. For this purpose, a corresponding recess or gap in which the wall is fitted is provided in the control circuit. At the same time, the contact terminals preferably fit at least with their axially external areas in corresponding recesses or contact openings of a punched grid or a printed circuit board of the control circuit, and are electrically and mechanically connected to the corresponding conductors of the control circuit, for example by brazing, tightening, electric welding or the like. This results in the advantage that it is possible to connect the windings in an extremely simple manner, as well as the advantage that the contact terminals serve simultaneously as elements for electrical contact and mechanical clamping of the control circuit. In the preferred embodiment, the control circuit rests with its lower side, preferably the underside of the punched grid or the printed circuit board, on the back of the ring. As a result, an additional stabilization of the clamping of the control circuit is achieved. Other embodiments of the invention are í * "? _____ > s¿. -.fi ***** - derive from the subordinate claims. We wish to point out that the contact of the ends of the windings by contact terminals that are provided in the stator body in combination with all the features described above and then of course can also be carried out independently of the injection of a layer of synthetic material around the stator teeth. The invention is explained below in more detail on the basis of an exemplary embodiment shown in the drawing. In the drawing, FIG. 1 shows a schematic representation of a 4-phase DC motor with its corresponding control circuit; 2 shows a perspective representation of a stator according to the invention; 3 shows a schematic representation of segments of a developed side elevation view of the stator of FIG. 1 to illustrate the winding process according to the invention, and FIG. 4 a perspective representation of the stator of FIG. 1 with the circuit of mounted control. Figure 1 shows schematic representation a 4-phase DC motor with a stator 1 in which the windings Wl, W2, W3 and W4 of the stator are provided. The windings Wl to W4 are wound on teeth or poles 3 of the stator 1. The indicated magnetic coupling of the opposite phases I and IIIeither of the corresponding windings Wl and W3 as well as of the phases II and IV or of the corresponding windings W2 and W4 is achieved by proceeding so that the windings Wl and W3 or W2 and W4 are wound on the same teeth of the winding. stator The winding and contact of the windings Wl and W3 or W2 and W4 is carried out in such a way that opposite magnetic fields are generated in front of the poles 3 of the stator in the areas facing the teeth or poles of a rotor (not shown). This is indicated in figure 1 by the points in the windings Wl to W4. Each winding is connected with one end or a contact to a direct current source 5. In each case another end or in each case another contact of each winding is connected with a controllable electronic switch SI, S2, S3, S4 which can be, for example, designed as a power semiconductor (for example power transistor). Field effect (FET)). Each of the switches SI to S4 is connected with its control input to an engine control unit 7, which i _-__ s__Í ^ I ^ ___ Efei_ _ilf¡f ?? fí? - in a manner known per se, it links the windings Wl to W4 during desired time intervals with the direct current source by means of the corresponding command of the switches SI to S4. In parallel to each switch SI to S4 controllable a diode DI to D4 is connected, the direction of passage of the diodes being selected so that when closing the respective switch it cuts the corresponding diode. By coupling the opposite phases I and III or II and IV in each case and the diodes D3 and DI or D4 and D2 it is possible to discharge the stored magnetic energy when the respective phase is switched off, by means of which an improvement of the degree of efficiency of the engine. Figure 2 shows the structure of the construction of a corresponding stator 1 in perspective view. The stator shown has twelve poles 3 of the stator. The stator body 9 comprises, in the usual manner, a main body of stator plates stacked perpendicular to the longitudinal axis of the stator. The package of the stator plates can first be formed in the usual way by stacking by punching, where in each case two or more sheets are joined by exerting a pressure in the form of a point.

Then the package of the stator plates is surrounded with a body of synthetic material applied by injection, being that a cover of synthetic material is produced at least in the internal area of the teeth of the stator that come into contact with the conductors of the windings Wl to W4. By this it is no longer necessary to carry out a powder coating of these areas of the stator teeth as practiced so far in order to prevent damage to the insulating layer of the stator teeth. winding wires, in particular during the winding process. Simultaneously, the auxiliary posts 11 of the winding are injected onto the front faces of the teeth 3 of the stator, which during the The winding of the windings Wl to W4 determines a conduction of the wires and at the same time fix in their position the parts of the winding projecting beyond the front faces of the teeth 3 of the stator. On its upper side the body 9 of the stator has 0 a ring 13 applied by injection with a back 13a. On this back 13a front the contact terminals 15 are pressurized. For this purpose the ring 13 is injected with corresponding recesses for the contact terminals, in which the contact terminals 15 are then pressed with their shoes. ^^ - wmteE ^ M ___ * __ ^ __ l _ ^ _ »_ S ^ _,. ^.? t_? ^ _ ^^ Afe - ^ ..« =. - made of sheet metal, for example by stamping or bending. The wall 17 of the ring 13 extending upwards above the back 13a of the ring 13 serves to fix and hold a control circuit 18, as can be seen in figure 4. For this the control circuit 18 can comprise a injection-molded punched grid 19 with a corresponding recess 21 in which the wall 17 of the ring 13 fits. The lower side of the punched grid 19 can for this rest on the back 13a of the ring 13. The contact terminals 15 fit their upper areas in contact openings 23 of the conductor strings 19a of the punched grid 19, and can be joined thereto by welding or the like. By applying synthetic material around the package of stator plates in a single operation, synthetic material being injected around the internal areas of stator teeth 3 and simultaneously injecting ring 13 and auxiliary posts 11 of the stator. winding results in an extremely economical manufacture of the stator 1. The arrangement of the contact terminals 15 directly in the stator 1 allows easy contact of the ends of the conductors forming the windings with the circuit 18 of control. Next, the procedure for winding the stator 1 is explained in FIG. 3: First, we would like to point out that in the exemplary embodiment represented, each of the windings Wl to W4 extends over a total of six stator teeth 3., which in a manner known per se are divided into two groups radially opposite each other in each case three adjacent stator teeth. As already explained above, these six stator teeth each have two coupled windings, specifically the windings Wl and W3 or W2 and W4. In Figure 3 two of these groups are illustrated, these windings are then designated as Wl and W3 for reasons of simplification. The six stator teeth 3 remaining for windings W2 and W4 are wound in an analogous manner. For this purpose, the procedure described below will be applied accordingly. Each of the windings Wl and W3 consists of several partial windings of individual wires connected in parallel due to the high current intensities that are required. According to the invention, 2 or 2 wires (i.e., an even number of wires) are wound simultaneously on the respective teeth 3 of the stator, in the example represented by the two wires 25, 27. For this purpose, the initial ends of the two wires 25, 27 are first joined in each case with a first 15? and a second 15n of the contact terminals 15. For this purpose the contact terminals 15 comprise V-shaped clamping grooves 15a into which the ends of the wires (insulated) are inserted and provisionally fixed by bending the walls of the clamping grooves 15a or by forming a loop. The connection can be effected, for example, with an independent welding device, the insulation of the wires being broken or preferably eliminated simultaneously with the linking process. After fixing the ends of the wires, the first tooth 3 of the stator of the first group of three is wound. In the exemplary embodiment shown in FIG. 3 this happens counterclockwise. After applying the desired number of turns, it is passed to the adjacent stator tooth and the latter is wound in the opposite direction with the desired number of turns (the central stator tooth 3 of the group on the left in FIG. 3). Finally, the last stator tooth of the first group of three is passed and the desired number of turns is applied. This happens again in the direction of winding the first stator tooth.

Next, the first stator tooth of the group of three diametrically opposed is passed (in figure 3 the right stator tooth of the group of three on the right) and the latter is wound. The winding of this second group of three is carried out analogously. After winding the last stator tooth of the second group of three (the left stator tooth of the group of three on the right in Figure 3), the end of the wire 25 joins the third contact terminal 15m and the end of the Wire 27 joins with the fourth 15? v contact terminal. The association of the ends of the wires to the contact terminals 15 is still irrelevant during this first partial winding process. Of course, it should be noted that which of the contact terminals 15 correspond to these windings Wl and W3. In other words, for the subsequent control of the windings it must be known which of the two windings correspond to which of the two contact terminals. The windings Wl and W3 are equivalent to each other because they have the same winding direction. After completion of this first partial winding process, a second partial winding process is carried out in the same way. The only difference is that the ends of the wires are joined to others clamping elements or clamping slots 15a of the first to fourth contact terminals. This allows a simple fixing of the ends of the wires without it being necessary to loosen the ends of the wires previously wound. However, in this second and eventually the following partial winding processes, care must be taken to preserve the chosen association of terminals 15? and 15m of contact to a winding, for example the winding Wl, or of the contact terminals 15n and 15? V to the other winding, for example the winding W3. Usually it will be determined in any way from the beginning that certain perfectly specific contact terminals correspond to windings or perfectly specific winding ends. By associating the ends of the wires to contact terminals determined from before the winding, and preserving the association during the partial winding process, it is possible in a simple manner to join the ends of the wires correctly with the correct contact terminals after the Partial winding process, without having to resort to additional measures such as marking the wires or carry out directionality measurements. This applies in particular in the case of a small amount of wires wound simultaneously (preferably two wires). Furthermore, by fixing the ends of the conductors immediately before or after the winding process, the advantage is obtained that the last turns are prevented from loosening in particular. The ease of operation of the wound stators during the assembly of the motor is also improved by virtue of the fact that there are no ends of the conductors forming the windings that could hinder the assembly. In total, so many partial winding processes are carried out until the required amount of parallel wires per winding Wl, W3 has been applied. The amount of clamping elements or clamping grooves 15a corresponds in this preferably to the number of partial winding processes required. The other two coupled windings W2 and W4 are processed analogously, and it should be noted that the winding direction is chosen correctly also with respect to the windings Wl and W3 already made. Naturally, the above process is not only applicable to DC motors of 4-phases, but also to motors with any number (pair) of phases, being that the windings of two phases will always be magnetically coupled.

Claims (4)

1. CLAIMS Stator for an electric motor, in particular for a brushless DC motor a) comprising a stator body with a predetermined amount of stator teeth for housing the stator windings, b) the stator body comprising a stator main body of magnetizable material c) in which an insulating layer is provided at least in the areas of the stator teeth in which the stator windings are housed or housed, this stator being characterized d) because the insulating layer is a layer of synthetic material injected around the main body, and e) because a stator body support member for contact terminals is injected in a single piece with the insulating layer, the ends of the windings being joined or connected to the terminals of corresponding contact, f) because the support element is designed as a ring concentric to the longitudinal axis of the state r that is provided on a front face of the stator body, g) because in the ring, recesses are provided for the contact terminals in which the contact terminals are housed, preferably by pressing them, h) because the contact terminals are designed simultaneously for electrical contact and the mechanical clamping of a control circuit preferably comprising a punched grid or a printed circuit board.
2. Stator according to claim 1, characterized in that the ring comprises a radially external back which preferably extends perpendicular to the longitudinal axis of the stator in which the contact terminals are provided.
3. 3. Stator according to claim 2, characterized in that the ring comprises, extending in a radially internal area from the back outwards in the direction of the longitudinal axis of the stator, a wall which serves to hold and fix a control circuit that it can be joined or it is attached to the stator. Stator according to one of claims 4 to 6, characterized in that the control circuit is supported with its lower side, ^ iii '^^^^ j ^^^ mUffi ¡ai. preferably the underside of the punched grid or the printed circuit board, on the back of the ring. Stator according to one of the preceding claims, characterized in that auxiliary winding posts are injected in a single piece with the injected layer which are provided on the front faces of the stator teeth in their radially outer areas, and which extend substantially in the axial direction. An electric motor, in particular a brushless DC motor, comprising a rotor, a stator according to one of claims 1 to 5 and a control circuit connected to the stator.