MXPA97007572A - Assembly of motor molded by injection and fabricac method - Google Patents

Abstract

An electric motor and the process to form this motor are provided using injection molding techniques to unify the stator assembly. The stator assembly (21) includes a stator lamination block (27) and preferably a metal front end cap (26) which is fixed to the lamination block (27) after the lamination block is insulated and winding. The winding ends with a plurality of conductive terminals (94) welding by transfer to the terminating ends of the winding. The mounting (21) of the stator with the front end cap (26) in place is placed in an injection molding die. Pressure is applied to the die, molded plastic is injected under pressure to fill the gaps in the stator assembly, and also to form a plastic mass which will serve as the rear end stage (25): The rear end stage (25) also it is molded with a connector portion (41) which fastens the conductive terminals (94) in place as part of the connector. A perforation (30) is formed in the stator assembly that provides mounting surfaces (31, 32) for the bearings (23, 24) in the assembly (20) of the rot

Description

MOUNTING MOTOR MOLDED BY INJECTION AND MANUFACTURING METHOD BACKGROUND OF THE INVENTION Field of the Technique The present invention relates to electric motors, and more particularly to a method of manufacturing and assembling related encapsulated electric motors.

DESCRIPTION OF THE RELATED TECHNIQUE The North American patents No 4,922,604 for Marshall et al. and 5,008,572 to Marshall et al., both assigned to the assignee of the present invention and incorporated herein by reference, describe an electric motor and a manufacturing method for obtaining accurate alignment of the bearings of an internally mounted rotor assembly. As more fully described in the above-referenced references, an electric motor comprising stator and rotor assemblies is manufactured by using an encapsulation compound for REF: 25566 unify the stator assembly and provide improved thermal characteristics. "U.S. Patent No. 4,015,154 to Tanaka et al., Discloses a method for making a molded motor having a first laminated ring plate and a second laminated ring plate molded into the motor body with a resin composition comprised of a mixture. of thermosetting resin and thermoplastic resin It is noted that a molded body of the thermoplastic resin alone is apt to be deformed due to the lack of heat resistance, and therefore such a resin is not suitable as a molding material for an engine or transformer. "Patent Abstracts of Japan, vol. 8, No. 226 (E-272), and JP-A-59-106864 disclose a method of extracting pole wire for a molded motor to prevent the molded material from leaking externally from the molding die. A liner or sheath is deployed around the wire and interposed between the opposite peripheral edges of the mold. The Patent Abstracts of Japan, vol. 5, No. 167 (E-79), and JP-A-56-94952 discloses a method for reducing the amount of resin needed to produce a molded motor by inserting fixed terminals into holes around the periphery of the laminated stator core.

The fixed terminals are made of thermoplastic resin having a transfer temperature which is lower than the temperature of the molding resin. The fixed terminals fuse the opposite ends of the motor at the time of molding without the need to apply molding resin around the circumference of the motor. "Briefly, improvements are sought which resolve more efficiently the aspects described above, and at the same time that maintain the benefits and advantages in the assembly of the motor and method as described in references '572 and' 604.

BRIEF DESCRIPTION OF THE INVENTION In view of the above, it is a main objective of the present invention to simplify and, in this way, obtain a mounting and manufacturing method for engines with a lower cost, compared to the one currently known. Another object of the present invention is to provide an electric motor assembly having improved thermal characteristics. In greater detail, it is an object of the present invention to eliminate the small air gap between the encapsulated coils and the metal of the aluminum end cap.

Even in greater detail, it is an object of the present invention to provide high dielectric paths of good thermal conductivity between the electrical conductor and the pole structure, and the exterior of the motor, in order to increase the capacity of the motor to dissipate heat. Another objective of the present invention is to provide a method of manufacturing an electrical one that means the method known and previously used by eliminating costs and time necessary for a second cycle of curing an encapsulating compound, and at the same time "'maintaining the integrity Structure of the final motor assembly Another further objective of the present invention is to provide an electric motor assembly having a simplified electrical connection and therefore improved between the internal stator windings and the external connector., advantages and other additional novel features of the invention will be set forth in part in the description that follows and in part will be apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention can be realized and are obtained by means of instrumentalities and combinations that are particularly indicated in the appended claims. To obtain the above objectives and other objectives, an aspect of the present invention is directed to a method for producing an electric motor, in which an intermediate or unfinished stator assembly is formed by compiling a block of stator laminations and winding stator The intermediate stator assembly is then placed in a mold, and molten plastic is injected under pressure into the mold, whereby the molten plastic is driven inside and fills the internal voids between the "" poles of the intermediate stator assembly. The casting also forms a rear end cap for mounting the stator The plastic used in this invention can be any thermoplastically processable resin, or mixtures of such resins.The resin may optionally include additives such as flame retardants, reinforcements, pigments. colored, fillers, plasticizers, heat stabilizers or light stabilizers, then a continuous hole is machined through the center of the molded stator assembly to produce a concentric hole to accommodate a rotor assembly; The perforation also provides mounting surfaces to receive the rotor mounting bearings. Finally, the rotor assembly is mounted on the stator assembly by inserting the rotor assembly into the continuous bore and coupling the rotor bearings with the mounting surfaces. A related aspect of the present invention is directed to the injection-molded electric motor assembly which includes a rotor assembly having a central rotor portion on the shaft or rotor shaft, and a rotor bearing positioned near each end of the rotor. rotor shaft. The unit stator assembly includes a stator lamination block which forms stator poles which carry the stator windings, and end caps .. front and rear. The stator and winding poles are substantially encapsulated by an injection molded plastic mass, which fills the space between the stator poles. The molded plastic also integrally forms the rear end cap. A continuous perforation formed in the stator assembly through the front end cap, the stator lamination block and the rear end layer, forms mounting surfaces on the end caps to receive the rotor bearings; the rotor assembly is transported within the bore by a coupling between the rotor bearings and the mounting surfaces in the end layers.

Having summarized the present invention as in the foregoing, the discussion will now be directed to a preferred embodiment of the invention. As an intermediate step of the manufacturing process of a preferred embodiment, a matrix of conductive terminals are melt welded to the stator windings. The rear end cap is formed by injection molded plastic molded to encircle the matrix of the terminals and form a connector housing around the conductive terminals. In this way, the motor assembly provides a connector that is easily adapted for electrical connection to an external or remote source to control the motor. The injection molded end cap is an extension of the mass molded by injection into the stator, and therefore provides an efficient continuous path for heat dissipation generated in the windings.

BRIEF DESCRIPTION OF THE DRAWINGS The appended drawings are incorporated and form part of the specification, and illustrate various aspects of the present invention, together with the description, serve to explain the effects of the invention. In the drawings: Figure 1 is a perspective view illustrating a fully assembled engine, constructed in accordance with one embodiment of the present invention; Figure 2 is a partially exploded view showing an engine according to the invention, with the rotor assembly removed from the stator assembly; Figure 3 is a process flow diagram illustrating the stages of construction of an engine according to the preferred embodiment of the present invention; Figure 4 is an elevation view illustrating "a partially assembled rotor, including a partially exploded view, Figure 5 is an elevation view illustrating a rotor assembly with bearings and bushings in place and ready for insertion into the rotor; the stator assembly, - Figure 6 is an elevation view of a single stator laminate, illustrating the stator poles directed inwards and the teeth of the pole, Figure 7 is a perspective view showing a rolling block assembled stator constituted of individual laminations, as illustrated in Figure 6, Figure 8 is a perspective view of the front end of the stator lamination block of Figure 7, with insulators and stator coils in place; Figure 9 is an exploded view as illustrated by the arrows in Figure 6, illustrating a stator assembly wound inside the caps and the connector in place, Figure 10 is a perspective view of the rear end of the unfinished stator assembly, showing the insulators, stator coils and the matrix of the connection terminals in place, - figure 11 is a partial view illustrating the matrix of the terminals connectors as they are placed in relation to the stator lamination block; Figure 12 is a partial view illustrating the partially completed stator assembly of Figure 9 after injection molding; Fig. 13 is a view similar to that of Fig. 12 illustrating the injection molded mount after which it has been machined and therefore ready for insertion of the rotor assembly; Fig. 14 is a side elevational view showing the molding device used in manufacturing the motor assembly of the present invention; Fig. 15 is a perspective view of a partial exploded view of the molding device shown in Fig. 14; Figure 16 is a partially exploded side view, and Figure 17 is an axial section taken along line 17-17 of Figure 16, respectively, showing an alternative engine construction adapted for the practice of the present invention.; Figure 18 is an elevation view of a rotor assembly for the motor of Figures 16 and 17; and Figures 19 and 20 are elevational cross-sectional views and an axial cross-sectional view taken along line 20-20 in Figure 19, respectively, showing a permanent magnet motor adapted for the practice of present invention. Reference will now be made in detail to the various currently preferred embodiments of the invention, examples of which are illustrated in the drawings: appendices.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Turning now to the drawings, figure 1 shows a perspective view of the hybrid permanent magnet progressive motor, and figure 2 shows a partially exploded view showing the rotor and the rotor retaining elements removed from the stator assembly. It will be noted that in the beginning, however, although the invention will be described in connection with a hybrid progressive motor, it is also applicable to other types of motor. For example, the invention is applicable to brushless variable reluctance progressive motors, permanent magnet brushless motor designs, switched reluctance motors, increased variable reluctance motors as well as improved and unimproved stage and hybrid stage type motors. Finally, the induction motors may also use the present invention as well as other types of motors, as will be apparent to those skilled in the art upon reading the following detailed description. With reference to FIGS. 1 and 2, there is shown a hybrid progressive motor generally designated 20, consisting of a stator assembly 21 and a rotor assembly 22. The rotor assembly is adjusted with bearing 23, 24 which in turn are mounted on the end caps 25, 26 which hold the rotor assembly 22 for rotation in the stator assembly 21. The end caps 25, 26 are interposed to a central stator lamination block 27 which forms the stator poles, which transport the stator windings (which are not shown in FIGS. 1 and 2). In the presently preferred embodiment, the stator laminations are aligned and initially fixed by welding seams 70 (see Figure 7) together with the corners of the rolling block. As will be described in more detail in the following, the rolling block is further fixed by means of high strength injection molded plastic which completely encapsulates the interior of the rolling block and preferably projects partially into the central bore 30 after of the molding. The perforation 30 is then machined by grinding * to form the bearing surfaces 31, 32 (see Figure 9) in the end stage 25, 26 and also to form a regular bore 30 through the rolling block 27 adjacent the bearing surfaces 31, 32. In the embodiment illustrated in Figure 2, the rings 36 of retention fix the assembly 22 rotor in the assembly.-21 stator. In another embodiment, the rotor assembly 22 is retained in the stator assembly by a snap-fit coupling between the bearings 23, 24 and the receiver surfaces 31, 32. The front end cap 26 has a flange 37 which at its once it has a surface 38 machined with a mounting projection 39 for positioning the motor on a mounting bracket. The mounting holes 40 provide means for mounting the motor to its bracket (not shown). The rear end cover 25 includes an integral electrical connector 41 for supplying power to the stator windings. As shown in Figure 2, the rotor assembly 22 includes a rotor shaft 50 which supports a rotor section 51 (ie, the portion of the rotor which is magnetically active) and bearings 23, 24 on the outside. In the illustrated embodiment, the rotor comprises toothed lamination sections 52, 53 separated by a permanent magnet 54. The magnet is placed to prepare the lamination sections 52, 53 with opposite magnetic polarities by making, for example, a lamination section 52 a north pole and the lamination section 53 a south pole. In one embodiment, the laminations are formed with external teeth, of the same spacing as the teeth associated with the stator poles of the stator assembly. Other stator / rotor pitch ratios such as 52/50 or 48/50 can also be used. As is known in the art, the teeth of section 53 are deflected by approximately half a step with respect to the teeth of section 52 in order to form a hybrid permanent magnet rotor. Therefore, when the winding of the stator is energized by a driving current coupled through the terminals of the connector 41, the rotating magnetic field which is produced in the stator tends to successively align the teeth of the sections 52, 53 of rotor lamination with the field of the stator teeth, which causes the motor to advance progressively in sequence. The control of the rotational speed and direction of the stator field therefore allows the control of the speed and direction of rotation of the rotor. Returning now to Figure 3, the process for manufacturing an engine according to the present invention is illustrated. By concentrating first on the rotor assembly, it is noted that the initial raw materials which constitute the rotor are held together in process step 100 and include rotor shafts, rotor laminations (or preblocks) and magnets. These articles are assembled in step 101 and the assembled rotor which results are best illustrated in figure 4. A rotor shaft 50 having a pair of lamination blocks 52, 53 placed thereon, with a magnet 54 is shown. permanent interposed between the rolling blocks forming a rotor section 51 designed to be driven by the rotating magnetic field produced by the stator. In a hybrid permanent magnet progressive motor, the rotor laminations 52 and 53 have alternating teeth and valleys of a given pitch in relation to (as described above) the pitch of the teeth at the stator poles. In addition, the teeth in sections 52 and 53 are offset one from the other by half a step. The magnet 54 serves to magnetically polarize the blocks 52, 53 with, for example, the block 52 constituting the north pole and the block 53 constituting the south pole. The shaft 50 has a pair of machined sections 60, 61 adapted to receive the inner race of the bearings 23, 24 (FIG. 5) for support of the rotor within the stator assembly. The shaft 50 may have its outlet end with a key as illustrated, or unlocked if desired, or with any other adapter configuration. The motor can also be configured with an output shaft at the rear end to form a double-ended motor. Such construction details are not part of the present invention and will not be emphasized here. Having assembled the rotor 22 in step 101 (FIG. 3), the rotor is then passed to a polishing station where the step 102 is carried out to polish the outer diameter of the rotor. Such polishing tends to produce teeth in the rolling blocks 52, 53 which have relatively sharp corners. In addition, the polishing stage produces a rotor which is substantially concentric and therefore can operate in a carefully machined stator perforation with a relatively small air gap. Having thus configured the magnetic section 51 of the rotor, and after machining, the debris is cleaned from the rotor, and subsequently the step 103 is carried out in which the bearings 22, 23 are assembled in the bearing surfaces 60, 61. rotor bearings. In the exemplary embodiment, the spacer bushings 62, 73 are interposed between the bearings 23, 24 and the rolling blocks 52, 53, respectively. The bearings run between the rolling block and the inner race of the bearings to form the spacer element to properly place the bearings on the shaft. The bearings are adjusted by pressure on the shaft, preferably in an appropriate device, in step 103. Referring to FIG. 5, the rotor assembly including the bearings 23, 24 and the bushings 62, 63 are shown. separation, which provide a rotor assembly, which is ready for insertion in the stator assembly. Figure 5 illustrates, in a somewhat exaggerated manner, the fact that the outer diameter of the bearings 23, 24 is slightly larger than the outer diameter of the rotor section 51. It has been previously noted that the stator perforation is a straight line through the formed perforation, in a single operation after the stator assembly. Therefore, by providing the bearings 23, 24 with a slightly larger outside diameter compared to the rotor section 51 allows the entire rotor assembly to be inserted into the bore, with an outer race of the bearing 23, 24 being housed in the bearing surfaces of the end stages while the rotor section 51 has a sufficient, though very small, space for rotation. The precision achieved in this way allows the engine to be configured with a relatively small air gap, which provides superior torque and efficient operation. As illustrated in Figure 3, the initial raw material component for the stator assembly process are individual stator laminations that are assembled in a step 105. An individual lamination 27a is illustrated in Figure 6. It can be seen that each lamination, which can be formed by stamping, has a series of poles 66a with a plurality of teeth 67a formed in each of the wells. The poles 66a are separated by spaces 68a which provide an area to receive the stator fins. The laminations also have perforated space holes 69a through which alignment bolts can be passed to initially align the stator assembly. Preferably, a space hole 69a is associated with each pole 66a so that the laminations of the stator are symmetrical and can be installed in any of eight orientations. Therefore, it is possible in the assembly to rotate the stator laminations one with respect to the other so that the degree of cleanliness from which the laminations are manufactured is not in one direction, which allows the magnetic properties to be averaged. of the lamination stack due to the grain. As illustrated in FIG. 7, step 105 (FIG. 3) is implemented by assembling a stack of laminations of a predetermined height and fixing the laminations together, in the illustrated manner by means of welds 70. Alternatively , pre-stacking (ie groups of laminations linked by stamped concavities formed during the lamination stamping operation) can be used.With the use of the welding technique, a stacking * of laminations under pressure is preferably placed, and calibrated automatically by the machinery so that the lamination stack is of the appropriate height before the welds are made, if laminations are not added or removed until the desired width is obtained, at which point the automatic welding equipment It is preferable to apply four welds 70 in the corner of the rolling stack, offset 90 degrees from each other, as shown in FIG. Assembled lamination therefore provides a pole structure 66 separated by winding spaces 68 between the poles, each pole structure having teeth 67 axially disposed of a predetermined pitch or deviation. It is also noted that the fixing holes 69 are aligned so that an alignment pin or an injection molding needle can pass through the lamination stack at the appropriate point in the assembly process. After the lamination stack is assembled, and in the optional case in which an "improved" motor is to be produced, in a step 105, elongate magnetic strips 85 are inserted in each space between the teeth 67 of the stator (FIG. see figure 12). As will be described below, the magnets which are inserted between the teeth of the stator tend to improve the magnetic properties of certain motor classes. Magnetic strips have sufficient frictional engagement and magnetic attraction for the voids within which they are inserted to temporarily hold the strips in place during the subsequent manufacturing stages until they are firmly fixed in their spaces, by means of injection molded plastic material.

Subsequent to step 105 of insertion of the magnet, if it is performed, or simple welding of the lamination stack 105 for an unimproved motor, as shown in FIG. 3, subsequent operations are carried out in the stacking of assembled lamination to associate the electrical components of the stator with the stacking and to magnetize the stator poles. In this regard, the stack is isolated, rolled up, and the rolls are finished. In Figure 3, the isolation step is indicated by the number 106. Preferably, discrete insulators are supplied along the stacking laminate of the welded stator in order to provide the proper insulation between the stator windings and the rolling stack. Returning briefly to Figure 8, one end of the insulator assembly is illustrated with the numeral 71 and shown completely aligned with the slot 68, as well as with the cover of the face 72 of each pole 66. The vertical insulating sections 71 ' retain the stator windings, and interconnect with the end cap when overlapped. Protective pins 71"isolate fasteners 28 and prevent contact between fasteners and coils.A coupling end for the isolator is illustrated in Figure 10 with the number 90. It is noted that isolator 90 is similar to isolator 71 in to the extent that it provides a face 92 for insulating the end of the pole, channels 93 which completely align with the slots within the pole and vertical projections 90 'for retaining the stator windings. the insulator section oriented towards the rear Since the rear end cover 25 is formed of molded plastic and the bolts are not used to fix them to the lamination stack 27, it can be seen that the bolt protectors 90"are not necessary . However, in a preferred embodiment, they are maintained so that the • • sections 71 and 90 of the insulator are interchangeable and only one type needs to be stacked. In addition, the bolt protectors 90"provide an irregular face which improves the bond formed between the molded rear end cap 25 and the lamination stack 27. Having thus isolated the pole structure, the coils illustrated schematically in the figure - '73 are applied (Figure 12), preferably automatically, to each of the poles in step 107 (Figure 3) The coils serve as a means to magnetize the poles on which they are rolled. In the typical case, a winding of significant dimension (more significant than the one illustrated in the figures) will accumulate in order to obtain necessary turns in each pole, however, it can be observed that the turns are isolated from the magnetic structure by means of the Sections 71, 90 Insulators Having wound the winding in step 107, the ends of the coil are then terminated in step 108. In this step, the conducting terminals 94 are Inean in a row or matrix by the separator 95 - the terminals have a projection end 94 'and a termination end 94"(see Figure 11). In the illustrated engine which has eight pole structures, each with a coil, eight terminals 94 are provided to finish the coil ends. Therefore, at the beginning of the coils, a first end of a coil is melt welded to the end 94"of termination of a bolt 94, is wound around four poles, then melt welded to the end of another end It will be appreciated that a larger matrix of the conductor terminals 94 may be desired if, for example, the coils are of two-wire winding, if a separate coil is desired for each pole, or alternatively, if a further number is provided. large stator pole, having configured the electrical components of the stator that includes the lamination stacking of the magnetic stator and the associated electrical components, step 110 (FIG. 3) is carried out to assemble the stator. In the preferred embodiment, this step is carried out by aligning and fixing the front end cap 26 with the lamination stack. Preferably, four self-sealing screws 28 fix the end cap 26 to the lamination stack 27, in a manner sufficient to maintain alignment during engine manufacture, and subsequently during engine operation. As will be described in more detail with reference to Figures 14 and 15, the molding device is adapted to maintain accurate alignment between the front end cap 26 and • * the lamination stack 21. Preferably, the front end cap 26 is cast aluminum and has pilot holes 80 which align with the fixing holes 69 of the lamination stack. In carrying out the invention, since the motor is to be filled under pressure with a molten plastic, the practice of the invention additionally contemplates sealing the stator elements to prevent leakage of the molten plastic during the injection step. This sealing is carried out in the present invention during the injection molding process. For example, as will be described below, an anvil is used to seal leaks around the front end cap, and pressure is applied to the mold during injection of high pressure molded plastic which prevents leakage during the injection step. According to the invention, the preliminary fixed assembly, aligned by means of the molding device (shown in Figures 14 and 15), is fixed permanently in position by injection molding the stator assembly, after which the concurrent machining of the bearing surfaces in the end caps and stator perforation provide a stationary and aligned stator assembly, ready to receive its associated rotor assembly. The molding step III (FIG. 3) is better understood with reference to FIGS. 14 and 15 which illustrate the molding step and FIG. 9 which shows the stator assembly after molding, and after removing the molded stator from the mold. Fig. 14 and 15 device. In these figures the matrix of the conductor terminals 94 is also shown where the windings of the stator end and place them in the external connector 41. Preferably, the molding is carried out with a central mandrel inserted through a perforation of the stator which provides a small space between the laminations of the stator and the mandrel. As a result, a thin layer of plastic 98 covers the teeth 67 of the stator pole and aligns the central bore that houses the rotor. The plastic additionally surrounds the windings of the stator, and fills the fixing holes 69. In fact, during the molding step molded plastic is driven into and flows through the fixing holes 69 and into the aligned pilot holes 80 provided in the front end stage. Once the assembly cools and the plastic has solidified, an integral plastic mass is formed within the pilot and fixing holes. Thus, the pilot holes 80 include a beveled counter-perforation 80 'which cooperates with the plastic mass to hold the front end cap still in alignment with the lamination stack of the stator. It is preferred to reinforce the plastic fasteners with self-sealing screws 28. In some embodiments, the molten plastic that is driven into the openings in the stator and the end cap can form plastic rims which will secure the end cap in place, at least for weak loads. In other cases, where the operating temperatures may be more severe, or the loads driven by the motor may be higher, it is preferred to use metal screws to improve the connection between the end cap 26 and the stator. It will be appreciated that it is the end cap 26 that is typically used to mount the motor to the apparatus which it drives. Thus, in the embodiment using screws to improve the connection, from the front end cap to the stator assembly, the self-obturating screws 28 have a slightly smaller diameter than the holes 80 of the end cap, are screwed in an auto way -obtaining in the fixing holes 69 for firmly fixing the end cap 26 to the stator housing. Subsequently, during the injection molding step, the molten plastic flows through the fixing holes and into the end cap, to encircle the exposed portions of the screws 28. When the motor is subsequently mounted in place at the fixing the front end cap 26 to the apparatus which is intended to be driven, the fixation provided by the injection molding combination and self-sealing screws provides a rigid assembly which maintains the integrity of the engine and resists relative movement between the components of the stator, even in the presence of significant excursions in the temperature encountered during the operation. The steel-to-steel contact between the screws and the stator assembly also serves to eliminate progressive deformations during cyclic motor temperature changes.

As shown in Figure 9, the rear end cap 25 is completely formed by the molded plastic in the lid 111 (Figure 3). The plastic of the end cap 25 surrounds the conductive terminals 94 and the spacer 95, to hold the terminals 94 in a fixed relationship, and to form a connector body. Prior to step III, and in the preferred embodiment, terminals 94 and spacer 95 are held in place solely by the rigidity of the stator windings that are fused to terminals 94 (see FIG. 11). However, alternatively, the "separator 95 and the conductive terminals can be formed integrally with the insulator 90 (FIG. 10), so as to be rigidly placed before the stage 1. It will be observed at this point that the fusion welding it is the preferred means of electrically and mechanically connecting the terminals 94 to the termination ends of the coil wires, Not only is a mechanical and electrical connection provided safe, but this connection can be obtained without the need to stretch the insulating varnish of the coils. The fusion welding step is carried out without the stretching of the insulation, and serves to melt through the insulation to the fusion welding point in order to obtain the safe mechanical and electrical bond mentioned above.

A connector housing 41 is placed around the conductive terminals 94, and is integrally formed as part of the rear end cover 25. In a beneficial way, this connector 41 configures the motor for easy electrical connection to a cable that is finally connected to the motor impeller to control the motor. It can be seen that, in this way, an external connector can be connected conveniently to the windings of the motor stator, and in this way they are placed in direct control of the operation of the motor. In an alternative embodiment, which is not shown in the figures, a motor can be manufactured in which both the front and rear end caps 26, 25 are formed of high strength injection molded plastic. However, it is preferred and illustrated to retain an aluminum front end cap, due mainly to the heat transfer characteristics of the aluminum. More specifically, since aluminum is a better thermal conductor than plastic, maintaining a front end cap 26 of aluminum provides better heat transfer, and therefore better heat dissipation, away from the engine. In this regard, the heat dissipation is further improved if the motor is mounted by means of mounting holes 40 (FIG. 2) to a structure that effectively serves as a heat sink. After the molding is complete and the stator assembly is removed from the molding device, the stator appears as suggested in Figure 12. Molded plastic material 82 completely covers all of the teeth 67 of the poles, fills the entire of the gaps around the coils shown in Figures 12 and 13, as well as all gaps in the end caps, to form a continuous surface extending through the center of the stator assembly. In addition, the molded plastic material is selected to have a heat transfer constant, which is substantially better than that of air, and therefore the motor is more suitable for driving heat generated in the stator to the environment. As a result, the accumulation of temperature in the motor is effectively dissipated, particularly in comparison with an engine having a conventional case or cover. Thermal transfer and therefore heat dissipation also improves compared to motors of the type described in the '572 and' 604 patents which have an encapsulated stator assembly, insofar as the injection molded motors have air pockets in smaller quantity and smaller.

Having molded the stator assembly, which includes the end stage 25 in step 111 (FIG. 3), a step 112 is performed to machine the central bore. Any of the various machining techniques can be used to form the central bore, which include boring, grinding, boring, burnishing or lapping. In the current preferred embodiment of the invention, a burnishing shape, some termed diamond-drilled finishing is used, preferably with multiple stations. Lapping can also be used; in drilling at very high volumes, drilling may be preferable. In the presently preferred practice of the invention, multiple diamond type finishing stations are used, and are arranged to ensure that part of the material is removed at each station. The initial cuts remove mainly plastic material from the stator and aluminum from the front end cap. As illustrated in FIG. 9, it is desired to form the central perforation so as to leave a thin layer of plastic 98 molded between the teeth 67 of the stator pole and the side walls of the central perforation. Alternatively, it may be desired to continue the burnishing operation until the perforation 33 has been opened so that the tools have contact with the laminations of the stator. Therefore, to the extent that successive burnishing operations are carried out, the material is finally removed from the teeth 72 of the stator assembly and at the same time from the bearing surfaces 31, 32, of the end caps for machining a continuous and regular hole 33 through the entire stator assembly. The machining in the end caps forms bearing surfaces for adjustment by division of the rotor bearings while the machining of the lamination stack cuts the corners of the stator pole teeth 67 to produce a uniform perforation for minimum air space and improved magnetic coupling. It will be appreciated that in the practice of the present invention no machining is required in both end caps 25, 26 before the finishing operation which forms the bearing surfaces. Typically, motors have machined flanges for precise motor mounting on the end-use apparatus. Therefore, upon completion of the burnishing operation and thus forming a central bore in the motor which will define the center line of rotation of the rotor, the bore is used as an alignment pilot for machining a mounting flange 38. the face of the engine. Typically, the flange is machined on a lathe, and after machining the mounting flange the tool is changed and the grooves 83 are machined on the bearing surfaces 31, 32 to accept the retaining rings 35, 36. After completion of step 113 for such finishing machining, the stator assembly is prepared to receive a rotor and thus produce an assembled motor. More particularly, a step 115 is carried out in which the rotor assembly produced in step 103 joins the stator assembly in step 113 to produce a complete motor. It is simply necessary to install one of the retaining rings, for example, the front ring 36 in the end cap 26, then "slide the motor assembly with the bearings into the bore 33. A pushing means 36a, for example a Wavy washer and spacers 36b, if necessary, are installed above the bearing to load the bearings in one direction After insertion of the rotor, the steel clip 36 is put in place resulting in a completed motor. Then a step 116 (FIG. 3) is performed to magnetize the rotor in a conventional manner One of the significant advantages which is obtained by the assembly techniques of the present invention is the ability to produce progressive motors - "improved" ie, motors that have magnetic inserts between the stator teeth to improve the flow trajectories and produce a corresponding improved operation. Reference is made to the following North American patents for a description of the improvement structure and function that is obtained by the insertion of magnets in the slots between the teeth of the pole structure: Horber, U.S. Patent No. 4,712,028, Mastromattei, U.S. Patent No. 4,713,570 and Gamble, US Patent No. 4,763,034. Figures 12 and 13 of the present application reflect the techniques of the patents mentioned in the foregoing applied to the present engine structure. Figure 12 also illustrates the thin slider of material 98 formed on the stationary teeth 67 during the molding operation and subsequently removed by machining. More particularly, with reference to Figure 12, it can be seen that the molded plastic material completely fills the interdental space including all the interstices between the magnets "-85 and the teeth 67, which covers all the magnets and teeth to form a thin layer of plastic material comprising a continuous surface through the perforation of the motor Figure 12 illustrates the motor after being molded and before burnishing the perforation As described in relation to figure 9, if it is desired, in one embodiment, to leave a thin layer of plastic on the stator pole teeth, Alternatively, it may be desired to continue the burnishing operation until the pole teeth of the stator are exposed. Figure 13 illustrates the condition after the drilling has been completed, showing a continuous surface for internal drilling, such a continuous surface in different parts in clude molded plastic material, exposed teeth 67 and exposed magnets 85 (when present). By maintaining the description of figures 12 and 13, no attempts are made to illustrate the inserts in other figures at a better scale in order to avoid confusion with the drawings. However, from the illustration of Figures 12 and 13, it will now be apparent to those skilled in the art, how the magnets are used in the practice of the present invention. As shown in Figures 12 and 13, magnetic segments 85 are inserted into the spaces between the teeth 67 of the stator '; Although in the past it has been necessary to stick the segments in place and then impregnate the vacuum, the faces of the poles, or to varnish the stator, such steps can be avoided. More particularly, the magnetic segments 85 are preferably relatively strong magnets such as samarium cobalt. Since the internal diameter of the stator can be burnished before the insertion of the rotor, it will be appreciated that the magnetic residues are generated as the magnetic segments are burnished. This waste is highly magnetic and tends to adhere to the laminations. However, in practicing the present invention, the molded plastic material is allowed to enter the internal perforation and thus completely encompasses the magnetic segments 85. A completely regular or smooth perforation is provided which remains regular to the extent in which it is lapped or burnished. Therefore, although magnet residues "highly adherent in the burnishing operation can be generated, since the internal perforation 33 is completely regular, it is a relatively simple task to mechanically clean the perforation, and provide a clean and unobstructed hole in the perforation. Figure 12 and 13 illustrate an additional benefit of the subsequent molding and burnishing process when used with the improved type motors It will be appreciated that the molded plastic material is driven into any crack in the recesses within the mold. the teeth, and serves as a bonding agent to keep the improved magnets in place.The subsequent burnishing of the molded stator produces a regular perforation in which the stator teeth and magnets can be exposed, the molded plastic material also forms part of the regular perforation and ensures the retention of the improved magnets in place in the spaces between the teeth. The plastic material between the teeth also serves an important purpose for unimproved engines equally. In most machining operations, which include the preferred diamond type finishing operation, the material is removed from the stator teeth by a tool which constantly moves in the same direction, often at a high relative speed. It is noted that when using the preferred diamond finishing technique, it is preferred to use a tool with a speed of approximately 650 rpm and a feed rate of approximately 7.87 cm (20") per minute.Without support material between the teeth, Particularly when cutting at high speed, the shearing effect of the tool against the unsupported teeth would tend to distort the back edges of the teeth as the material is cut from the face of the tooth.The injection molding of the stator in a manner such that all the spaces between the teeth are filled with high-strength plastic before machining puts a layer of the support material between the teeth so that the tool that removes the material from the teeth is supported by the support material in the space and does not distort or subject to shear so that a deformation occurs on the edge as it is machined on the please. The result is very precise edges on the teeth substantially free of distortion, and such sharp teeth contribute to the uniformity of magnetic paths through the motor. Having previously referred to the above, a more detailed reference will now be made collectively to Figures 14 and 15, which show the mold device. As used in the present, the. terms "plastic", "molten plastic", "high strength cast plastic", "molded plastic material" and "plastic material" are defined as any thermoplastically processable resin. Examples of suitable thermoplastic resins include, but are not limited to, thermoplastic resins such as 6,6-polyamide, 6-polyamide, 4,6-polyamide, 12,1-polyamide, 6,1-polyamide, polyamides containing aromatic monomers, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, aromatic polyesters, liquid crystal polymers, polycyclohexanedimethylol terephthalate, copolyethers, polyphenylene sulfide, polyacyl polymers, polypropylene, polyethylene, polyacetals, polymethylpentene, polyetherimides, polycarbonate , polysulfone, polyethersulfone, polyphenylene oxide, polystyrene, styrene copolymer, styrene and rubber graft blends and copolymers, and glass reinforced or modified versions for impact of such resins. Mixtures of these resins such as polyphenylene oxide and mixtures of polyamide, and polycarbonate and polybutylene terephthalate can also be used in this invention. A preferred thermoplastic resin is a thermoplastic molded resin of glass reinforced polyethylene terephthalate such as that sold by E.I. du Pont de Nemours and Company of Wilmington, Delaware, under the trade name Rynite 530. Optionally, the thermoplastic resins may contain flame retardant additives. Thermoplastic resins can contain various types of reinforcements or fillers. You can use glass fibers or fiber, carbon to provide reinforced plastics. Various color pigments, such as titanium dioxide, can be added to the resin. Clays, calcium phosphate, calcium carbonate can be used as fillers to provide bulk, and many other fillers such as talc and mica can be used to reinforce the material, add strength or modify other properties of the finished product such as rigidity. The resins can also contain plasticizers and stabilizers against heat and light. The amount of reinforcement or filler material used can vary from about 1 to 70 weight percent, based on the weight of the polymer and the filler material present. The preferred type of reinforcement is glass fiber and it is preferred that the glass fiber be present in an amount of about 15 to 55 weight percent based on the total weight of the polymer and the filler material present. The thermoplastic resins' * can be prepared by methods well known in the art, when reinforcements or fillers are used, these can be added to the thermoplastic polymers during the preparation of the resins or they can be compounded in a separate step of according to conventional methods known in the art. Preferably, the mold device includes a front portion comprising a divided frame 104 having portions 104a and 104b which are joined to circumscribe the front end cover 26. An anvil member 120 is associated with the frame 104a, 104b to help retain the apparatus together when high pressure is applied to the dies in the injection molding process. Typically, the pressures applied during injection molding, which correspond to approximately 281 kg / cm2 (4,000 psi) and without the anvil encircling the end cap, the material of the end cap would likely break. The high pressure applied to the die, together with the anvil 120, also tends to seal the line formed at the junction of the front end cover 28 and the stator assembly, so that molten plastic injected under pressure will be retained within the motor and will not flow through the potential leak path between the end cap and the stator assembly. The frame 104 also includes a recess 105 (FIG. 14) that fits the front end cap 26, whereby the face of the end cap 26 abuts the frame recess 105, which advantageously provides a surface of support which prevents the molten plastic from flowing out of the pilot orifices 80. The mold device also includes a connector insert 106 and a rear portion 107. The rear portion 107 includes a channel 108 which defines a fluid passage through which the molten plastic flows to achieve the stator assembly. The rear portion 107 also includes a cavity 109 that defines the space for the rear end cover 25, which is formed of injected plastic. The connector insert 106 is positioned along the rear portion 107 so as to form a connector 41 (FIG. 1) that is integrally formed with the rear end cover 25. The mold device further includes a mandrel 110 which is inserted through the center of the stator assembly to form the central cylindrical bore. The mandrel 110 has a slightly smaller diameter than the side walls of the stator assembly 27, as defined by the stator poles 67 projecting inward, thereby providing a small cylindrical space in which the molten plastic flows. to cover the teeth of the pole (see also figure 9). The mandrel 110 is fixed in alignment between the portions 104 and 107 of the front and rear ends of the mold device, and thus, in this way, ensures proper alignment of the central bore within the stator assembly. Once the stator assembly 27 is fixed within the mold device, pressure is applied to the device, and molten plastic is injected under pressure into the channel 108. The channel directs the molten plastic to the chamber 109, which is filled to define the rear end cover 25. The molten plastic flows under pressure through other parts of the stator assembly, which include the space 68 between the poles of the stator (Figure 6), the fixing holes 69 and pilot holes 80, the annular chamber 112 defined by the cover of the front end and the cylindrical space between the poles 67 of the stator and the mandrel 110 to form a slide 98 (FIG. 15). Once the assembly is cooled and the plastic has solidified, then the mold device is removed, and the burnishing process is carried out in the previously described rotor assembly. However, it should be noted that the injection molding operation is a relatively fast manufacturing process, and the subsequent cooling operation is also, correspondingly, fast. In contrast to previous molded motors which require one or two curing cycles in an oven, according to the present invention, the molten plastic which is injected into the motor at a very high temperature begins to cool almost immediately. Shortly after the end of the injection cycle, the plastic has cooled enough to solidify. Once this occurs, pressure is released in the mold, and the engine can be taken to the next station for subsequent operation, and will cool in the course. There is no need for curing in an internal material furnace, simply allowing an adequate time to cool the plastic mass after solidification, so that subsequent operations can be carried out. A typical processing time of two hours for an encapsulated motor (encapsulation and curing cycle) is reduced to less than one minute with the injection molding process described herein. The nature of the connections between the terminated ends of the coil and the terminals of the connector also do not degrade in any way. The injection molding process operates at a temperature which is incompatible with many common forms of printed circuit boards and therefore, printed circuit boards which have been used in the past will require special adaptations in order to make them compatible with injection molding temperatures. Therefore, special printed circuit boards with thin sheets adhering adequately to the substrates will be necessary to withstand the injection molding temperatures. In the practice of the present invention, these difficulties are avoided by the use of metal bolts which are melt welded directly to the terminating ends of the coils. This not only eliminates the need and costs of a printed circuit board, but also provides a secure mechanical and electrical connection which is fully compatible with the temperatures and pressures of the injection molding process.

It will also be noted that part but not all of the advantages can be obtained in certain modified constructions of the invention. For example, in low cost motors and with reference to Fig. 16-18, the bearing surface 31 in the rear end cap 35 can be manufactured to fit a bearing much smaller than the bearing surface 32 of the cap of front end. It is noted that the primary bearing wear in an engine is at the front of the bearing, and therefore production savings can be obtained by using a smaller bearing at the rear of the shaft. This arrangement is easily adapted to the invention, ... except that the formation of the central perforation of the stator is modified. A further alternative illustrated in these figures, as will be described in greater detail in the following, is the application of the invention to different types of engines. The motor of Figures 16-18 is configured as a cheap universal motor, rather than the progressive and preferred mode. The stator assembly is shown in Figures 16 and 17 and includes a cylindrical stator body 150 and a pole structure 151, 152. The pole structure is formed as part of the body 150, or alternatively it can be attached to the body. The coils 153, 154 serve to magnetize the poles 151, 152.

In the low cost motor of Figures 16, 18, it is preferred to form both end caps by injection molding. Therefore, a front end cap 155 having mounting holes 156 formed to serve the purpose of a mounting flange is formed at one end of the stator body 150. A rear end cap 157, preferably having an electrical connector 158 formed therein, is positioned at the outer end of the cylindrical body 150. As best seen in FIG. 17, a plastic mass 160 fills the stator with the exception of a cylindrical opening 161 which is adapted to receive the rotor.The plastic mass extends to both end layers 156 and 157 in FIG. the embodiment illustrated and actually form both end layers.It will be noted that the plastic mass 160 encapsulates the coils 154 and fills all of the available voids within the stator body 150. The rotor for this motor is shown in FIG. 18. A central cylindrical portion 170, which is illustrated in the drawing only schematically, forms a magnetically active portion of the rotor.It is placed in a central shaft 171 intermediate to a pair of bearings as bearing surfaces. the previous embodiment, a bearing 172 of relatively large diameter, which is approximately the same diameter as the portion 170 of the rotor, (preferably slightly larger than the rotor) is placed on one end of the shaft. The second end of the shaft in the embodiment of FIG. 18 is simply machined with the number 173 for interface with a bushing placed in the associated end cap. When the motor is configured as a universal motor, the central portion of the rotor 170 will be formed to include a switch for interaction with the brushes placed in the stator assembly. Although not illustrated in the drawings, the universal motor also has brushes in the stator that fuse with a switch in the rotor. The description of the brush holder contained in the description of a direct current motor (Figures 19-20) also applies to the motor described in Figures 16, 17 and 18. They are not shown in order to preserve clarity, and focus on the encapsulation aspect of the invention. Returning attention again to the stator, it will be noted that the perforation 176 as best seen in FIG. 16, is continuous from the front end cap 156 toward the central portion of the rotor, but briefly stops at the rear end cap 157. A bearing mounting surface 174 is formed in the front end cap 156 to support the bearing 172. The rear end cap 157 has a smaller opening 175 which also serves as a bearing support.

Positioned in the opening 175 is a bushing 176 which interposes with the surface 173 machined in the rotor shaft to form a bearing structure for the rear end of the rotor shaft. Although the central perforation is progressive in this manner, the motor provides the advantageous features of the invention and includes at least one injection molded end cap, with this end layer having a bearing support surface formed therein for Hold the rotor shaft. The stator is encapsulated with an injection molding compound to provide regular perforation *, good transfer and heat dissipation, and a tough unified structure. The electrical connections can be made as in the previous mode. Many alternatives are also available with this motor configuration. Among these is the possibility of eliminating the burnishing or lapping of the central portion of the perforation 161 and in some cases, the machining of the bearing support surfaces. Therefore, in some applications, particularly such as a universal motor in which the size of the air gap between the rotor and the stator poles is not so critical, the inner surface 179 of the central portion of the stator can be left in its configuration "as it is molded" without additional lapping or burnishing. Therefore, the only machining operations which can be performed are those which form the bearing bearing surfaces 174, 176 in the respective end caps 155, 157. The use of a bearing 175 also illustrates a further alternative in which the bearing support surfaces do not need to be machined. Therefore, the surfaces 174, 175 in a particularly inexpensive motor can simply be molded to an appropriate size and the bearing member press fit into the molded openings. Bushings such as the metallic bushing 175 illustrated in Fig. 16 can be used or polymer bushings can also be used in the same manner. This structure is particularly advantageous for a very low cost motor such as a motor which is to be used in automotive applications for seat setters or the like. This form of motor is also best illustrated in FIGS. 19 and 20 which represent a cost-effective direct current motor which can make use of pressure-adjusting bearing structures, such as polymer bearings which adjust by pressure to reduce the manufacturing costs of such an engine. Figures 19 and 20 show an alternative configuration which is similar to the previous alternative in providing bearing surfaces in the respective end caps of different size, but which differs from that embodiment in the electric and magnetic form of the engine. The motor of figures 19 and 20 is a permanent magnet motor. As such, the poles do not require coils or windings, and the permanently magnetized polarization of these motors provides a means to magnetize the poles. Returning now to the drawings more specifically, it will be noted that the stator is based on a stator body 180. As best shown in Fig. 20, a pair of permanent magnets 181, 182 are attached or fixed to the body 180. The motor of Figs. 19 and 20 can be formed with a metal front end cap or with an end cap injection molded front, as desired. In order to reduce costs in the motor of Figures 19 and 20, the front end cap 183 is injection molded, as is the rear end cap. Numeral 185 shows a mounting flange with mounting holes in the front end cap 183. As in other embodiments, a mass 187 of injection molded plastic is formed in the stator body which encapsulates the poles and magnetic structure 181, 182, filling all the gaps in the body, which forms at least the rear end cap 184, and in this case also the front end cap 187. This embodiment also shows the use of short locating terminals 190 which are fixed to the metal part of the stator body and serve as fixings for the plastic mass after it solidifies. The motor of FIGS. 19 and 20 is a direct current motor and therefore the motor requires a switch structure illustrated with the numeral 192. The brush holders 193, 194 are permanently fixed in position in the plastic mass during the process of injection molding. As is conventional, brush support caps are provided to allow removal. of brushes 193a, 194a for engine maintenance. The wiring 195 is shown schematically by connecting the brush supports to a connector 196. Therefore, the entire brush structure is permanently fixed in position together with its wiring during the injection molding process. The motor of Figures 19 and 20 also shows the implementation of cost reduction by means of a rear end cap bearing of reduced size, therefore, the front end cap 183 has a bearing support surface 200 formed in the same, which is approximately the same size as the central perforation 201. However, the rear end cap 184 has a smaller diameter bearing support surface 202 formed therein. The roller bearings can be used as the bearings in the front and rear end cap. However, for a low cost version, the motor of Figure 19, preferably uses bushings that snap-fit within the bearing support surfaces 200, 202, machined coupling inspections of the rotor shaft 206. Preferably, the support surfaces are injection molded by sufficient precision and a suitable finish to allow the bushings to snap into position without the need to first machine the bearing support surface. In all of these alternative embodiments, the motor stator is injection molded as described in detail above to completely encapsulate the poles, coils and other materials in the stator and to form a regular bore-through the center of the stator . In one embodiment, the main length of the perforation, in the region of the poles, is simply that which is formed by the mandrel in the injection molding device, and only the bearing surfaces in the front and rear caps are machined . In the alternative mode, a regular bore is machined through the front end cap and the stator pole section, and a second smaller diameter bearing machined on its surface in the rear end cap. In an alternative embodiment, no machining is required for the bore or bearing support surfaces. In all cases, however, the central perforation which is presented to the rotor is a substantially continuous mass filled by the encapsulated injection molded material, and the fact that the stator is filled with such material provides improved properties such as thermal conductivity. . Now it will be appreciated that what has been provided - is a new and reliable assembled electric motor in which the stator is assembled from substantially unmachined parts. After a lamination stack is assembled, insulated, rolled and finished, an end cap is placed without machining at the front end of the laminate stack and initially fixed in alignment to form an intermediate assembly. Once the intermediate assembly is fixed, it is then molded to form the rear end cap and the integral connector is permanently fixed in alignment which has been initially fixed. Then an internal bore is machined to produce a straight central bore, regular and uninterrupted to receive the rotor, and form bearing surfaces in the end caps. The previously assembled rotor assembly is then inserted into the regular bore of the stator assembly, fixed in place, and the motor, after magnetization of the rotor is ready for service. The above description of the various preferred embodiments of the invention has been presented for purposes of illustration and description. It is not considered to be exhaustive or limiting of the invention to the precise forms described. Modifications or obvious variations are possible in light of the above teachings. In the modalities discussed are chosen and described to provide the best illustration of the principles of the invention and their practical application by allowing a person ordinarily skilled in the art to use the invention in various ways and with various modifications that are appropriate to the use particular proposed. The entirety of such modifications and variations is within the scope of the invention, determined by the appended claims, which are interpreted in accordance with the spirit to which they legitimately, legally and equitably qualify.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (42)

1. A method for producing an electric motor, characterized in that it comprises the steps of: constructing a rotor assembly on a shaft or rotor shaft, the rotor assembly has bearings connected near the ends of the rotor shaft, - forming a stator assembly intermediate when assembling a stack of stator laminations that have stator poles, isolating the stator poles and winding the stator poles with stator winding, - placing the intermediate stator assembly in a mold device that includes an internal cavity shaped to defining a rear end cap for the stator assembly and a mandrel projecting through the center of the intermediate stator assembly to form a central bore; Unify the stator assembly by injecting a molten thermoplastic resin under pressure into the mold device, whereby the molten plastic is driven into the intermediate stator assembly to encapsulate the stator windings, fill the gaps or voids inside and fill the cavity of the mold to form a rear end cap; cool the assembly to solidify the molten plastic in a plastic mass, the plastic mass extends and includes the formed end cap, - machining a continuous perforation through the molded stator assembly, to produce a concentric hole for the rotor assembly, the drilling also produces mounting surfaces to receive the rotor mounting bearings, - and mount the rotor assembly on the stator assembly by inserting the rotor assembly into the continuous bore and coupling the rotor bearings with the mounting surfaces .

2. The method according to claim 1, characterized in that the mold device includes a connector forming portion and the method additionally includes the step of placing the connector forming portion in relation to the mold cavity forming the rear end cap, so that the unification cap forms a plastic connector that is integral with the rear end cap.

3. The method according to claim 2, characterized in that it additionally includes the step of providing a plurality of conductive terminals or pins and electrically connecting the conductive terminals to the stator windings and additionally placing the conductive terminals inside the forming portion of the connector of the mold to provide adequate alignment of the conductive terminals with the connector.

4. The method according to claim 2, characterized in that it additionally includes the steps of providing a plurality of conductive terminals melt-soldered to the conductive terminals to the windings of the stator to form mechanical and electrical connections thereto, and fix the terminals in position by flowing molten plastic under pressure around the terminals in the unification stage.

5. The method according to claim 1, characterized in that the forming step includes stacking stator laminations having aligned fixing holes, winding the stacking stack with stator winding and placing a front end cap having pilot holes aligned with the stator windings. fixing holes in the rolling stack.

6. The method according to claim 5, characterized in that the molten plastic in the unification stage flows through the fixing holes and into the pilot holes of the end cap.

7. The method according to claim 5, characterized in that it includes the step of inserting metal fasteners to fix the front end cap to the lamination stack before the unification stage.

8. The method according to claim 1, characterized in that the forming step includes inserting an insulator in the intermediate stator assembly so as to circumvent the stator poles, and wrapping the stator windings on the insulator.

9. The method according to claim 8, characterized in that the molten plastic in the unifying stage is formed in such a way that it encapsulates the insulator, the stator poles and the stator windings.

10. The method according to claim 1, characterized in that the molten plastic in the unification stage is formed so as to encapsulate the stator poles and the wound stators and forms a front end cap opposite the rear end cap.

11. The method according to claim 1, characterized in that it additionally includes the step of fusion welding a plurality of conductive terminals to the stator windings.

12. The method according to claim 11, characterized in that the plastic is molded to form a rear end cap having an integral connector that surrounds the plurality of conductive terminals.

13. The method according to claim 1, characterized in that the stator laminations have a plurality of stator poles facing inward, each pole having a plurality of pole teeth separated by spaces, and in which the molten plastic encapsulates the assembly of stator so that the plastic deposits in the spaces between the teeth of the stator.

14. The method according to claim 1, characterized in that it additionally comprises the step of providing as the thermoplastically processable resin a resin selected from the group consisting of 6,6-polyamide, 6-polyamide, 4,6-polyamide, 12, 12-polyamide, 6, 12-polyamide, polyamides containing aromatic monomers, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, aromatic polyesters, liquid crystal polymers, polycyclohexanedimethyl terephthalate, copolyethers, sulfur polyphenylene, polylacrylics, polypropylene, polyethylene, polyacetals, polymethylpentene, polyetherimides, polycarbonate, polysulfone, polyethersulfone, polyphenylene oxide, polystyrene, styrene copolymer, blends and styrene graft and rubber graft, and mixtures thereof.

15. The method according to claim 14, characterized in that it additionally comprises the step of adding a filling material to the resin.

16. The method according to claim 14, characterized in that it additionally comprises the step of adding a fiberglass or carbon fiber reinforcement to the resin.

17. The method according to claim 1, characterized in that it additionally comprises the step of providing, like the plastic, a molded thermoplastic resin of glass reinforced polyethylene terephthalate.

18. A method for producing an electric motor, characterized in that it comprises the steps of: constructing a rotor assembly on a rotor shaft, the rotor assembly has bearings adapted to bear by bearings located near the ends of the rotor shaft, - forming a intermediate stator assembly having stator poles and means for magnetizing the stator poles; placing the intermediate stator assembly within the mold device including an internal cavity shaped to define the rear end cap for the stator assembly and a mandrel projecting through the center of the intermediate stator assembly to form a central bore; Unify the stator assembly to the glass-reinforced thermoplastic resin injector, melted under pressure in the mold device, whereby the molten plastic is driven within the intermediate stator assembly to encapsulate the stator poles, fill the gaps or voids inside and filling the mold cavity to form the rear end layer, - cooling the assembly to solidify the molten plastic into a plastic mass, the plastic mass forming a central bore extending between the formed rear end cap and a front end cap separate that has a flange for mounting the motor on a surface; forming bearing bearing surfaces on the end plates, the bearing surfaces are sized to receive the bearings adapted to support the rotor, and mounting the rotor assembly on the stator assembly by inserting the rotor assembly into the Continuous drilling and coupling the rotor bearings with the mounting surfaces.

19. The method according to claim 18, characterized in that the step of forming the bearing support surfaces forms a larger diameter bearing support surface in the front end cap than in the rear end cap.

20. The method according to claim 19, characterized in that the step of forming the bearing support surfaces includes the step of machining a regular continuous perforation through the front end cap in the central perforation, but ends short in the cap of rear end, and machining a smaller diameter bearing support surface in the rear end cap.

21. The method according to claim 18, characterized in that it additionally comprises the step of providing as a thermoplastically processable resin a resin selected from the group consisting of 6,6-polyamide, 6-polyamide, 4,6-polyamide, 12, 12-polyamide, 6, 12-polyamide, polyamides containing aromatic monomers, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, aromatic polyesters, liquid crystal polymers, polycyclohexanedimethyl terephthalate, copolyethers, sulfur polyphenylene, polylacrylics, polypropylene, polyethylene, polyacetals, polymethylpentene, polyetherimides, polycarbonate, polysulfone, polyethersulfone, polyphenylene oxide, polystyrene, styrene copolymer, styrene and rubber graft blends and copolymers, and mixtures thereof.

22. The method according to claim 18, characterized in that it additionally comprises the step of providing, like the plastic, a molded thermoplastic resin of polyethylene terephthalate reinforced with glass.

23. An injection-molded electric motor assembly, characterized in that it comprises: a rotor assembly having a central rotor portion on a rotor shaft, and a rotor bearing positioned near each end of the rotor shaft; a stator assembly that includes a stator stacking stack forming stator poles, stator windings supported on the stator poles, a front end cap positioned at one end of the stacking stack and a plastic unifying member of the stator. high strength comprising an unitary, injection molded thermoplastic resin, which substantially encapsulates the stator poles and coils and fills the interior voids of the rolling stack, thereby unifying the stator assembly, the plastic mass extends and forms the rear end cap positioned at the other end of the lamination stack opposite the front end cap; and a continuous perforation formed in the stator assembly through the front end cap, the stator lamination stack and the rear end cap, the continuous perforation defines mounting surfaces on the end caps to receive the rotor bearings , the rotor assembly is supported within the bore formed in the stator assembly with the rotor bearings engaging with the mounting surfaces on the end caps, an air gap is defined between the central rotor portion and the stack of stator lamination.

24. The electric motor according to claim 23, characterized in that the front end cap is made of metal and has pilot holes, the lamination stack has fixing holes, the plastic mass extends from the fixing holes in the lamination stack to the holes and the front end cap to form plastic rims which attach the front end cap to the lamination stack.

25. The electric motor according to claim 23, characterized in that the front end cap is made of metal and has pilot holes which are aligned with fixing holes in the rolling stack, threaded fasteners inserted through the pilot holes within the fixing holes to fix the front end cap to the lamination stack and prevent progressive deformation; the plastic mass encloses the threaded fasteners and prevents the front end cap.

26. The electric motor according to claim 23, characterized in that the front end cap is an injection molded plastic member that is part of the plastic mass, the front end cap further has a bearing support surface formed directly on the plastic mass

27. The electric motor according to claim 23, characterized in that the stator laminations "have a plurality of stator poles oriented inwards, each of the poles has a plurality of teeth oriented inwards separated by spaces, the plastic mass extends within of the spaces.

28. The electric motor according to claim 26, characterized in that additionally because it includes magnetic inserts in the spaces, the plastic mass in the spaces serves to fix the inserts in the spaces.

29. The electric motor according to claim 23, characterized in that the molded rear end cap encapsulates an insulator insert substantially enclosing the stator poles, the insulator supports the stator windings.

30. The electric motor according to claim 23, characterized in that the matrix of conductive terminals are electrically connected to the stator windings, and the molded rear end cap includes a connector housing integrally formed of injection molded plastic that is placed around the matrix of the terminals, the housing is adapted to receive a matching connector.

31. The electric motor according to claim 30, characterized in that the electrical connections between the conductive terminals and the windings of the stator comprise fusion solders that fix the terminals to the coils.

32. The electric motor according to claim 23, characterized in that the front end cap is formed integrally of injection molded plastic.

33. The electric motor according to claim 23, characterized in that the plastic is a thermoplastically processable resin.

34. The electric motor according to claim 23, characterized in that the thermoplastically processable resin is selected from the group consisting of 6, 6-polyamide, 6-polyamide, 4,6-polyamide, 12,12-polyamide, 6,12-polyamide , polyamide- containing aromatic monomers, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, aromatic polyesters, liquid crystal polymers, polycyclohexanedimethyl terephthalate, copolyetheresters, polyphenylene sulfide, polyacyl polypropylene, polyethylene, polyacetals, polymethylpentene, polyetherimides, polycarbonate, polysulfone, polyethersulfone, polyphenylene oxide, polystyrene, styrene copolymer, blends and copolymers of styrene and rubber, and mixtures thereof.

35. The electric motor according to claim 34, characterized in that the plastic additionally comprises a filling material.

36. The electric motor according to claim 34, characterized in that the plastic additionally comprises a glass or carbon fiber reinforcement.

37. The electric motor according to claim 23, characterized in that the plastic is a molded thermoplastic resin of polyethylene terephthalate reinforced with glass.

38. An injection-molded electric motor assembly, characterized in that it comprises: a rotor assembly having a central rotor portion on a rotor shaft, and rotor bearings positioned near each end of the rotor shaft, - a unitary stator assembly including stator poles and means for magnetizing the stator poles, a front end cap positioned on one end of the stacking stack having a rim for mounting the stalk on a surface and having a plastic unifying member comprising a thermoplastic resin glass-reinforced injection molded, unitary, which substantially encapsulates the stator poles and fills the interior spaces in the stator, so that unifies the stator assembly, the plastic mass extends and forms a rear end cap placed at the other end of the opposite laminated stacking to the front end cap, - and bearing support surfaces in the front and rear end caps separated by a perforation of a size sufficient to receive the central rotor portion, the bearing support surfaces define mounting surfaces in the end caps to receive the rotor bearings, the rotor assembly is transported or supported on the perforation formed in the stator assembly with the rotor bearings that engage the surfaces of the end cap, an air gap is defined between the central rotor portion and the stator lamination stack.

39. The electric motor according to claim 38, characterized in that the bearing support surface for the front end cap has a larger diameter than the bearing support surface for the rear end cap.

40. The electric motor according to claim 39, characterized in that the bearing support surface for the front end cap continues in a regular bore formed through the central borehole but shortly ending in o ~ in the cap rear end, a smaller diameter bearing support surface is formed in the rear end cap.

41. The electric motor according to claim 38, characterized in that the thermoplastically processable resin is selected from the group consisting of 6, 6-polyamide, 6-polyimide, 4,6-polyamide, 12, 12-polyamide, 6,12-polyamide , polyamides containing aromatic monomers, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, aromatic polyesters, liquid crystal polymers, polycyclohexanedimethylol terephthalate, copolyetheresters, polyphenylene sulfide, polylacyls, polypropylene, polyethylene, polyacetals, polymethylpentene , polyetherimides, polycarbonate, polysulfone, polyethersulfone, polyphenylene oxide, polystyrene, styrene copolymer, mixtures and graft copolymers of styrene and rubber, and mixtures thereof.

42. The electric motor according to claim 38, characterized in that the plastic is a molded thermoplastic resin of polyethylene terephthalate reinforced with glass.