Abstract:
The present disclosure relates to an electrical connection system and assembly for a brushless electromagnetic motor including a coiled stator assembly with P electric phases and X coils per phase, each coil exhibiting in proximity a body furnished with two connection slots, a first sub-assembly formed of W tracks cut in a conducting sheet, the tracks forming W coplanar output tracks, W being an integer number lying between P and P+1, each of the W tracks terminating in at least one end folded back perpendicularly to the plane of the tracks, the shape of the folded back end being complementary to the shape of the connection slot, the tracks being joined by an insulating plastic material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Phase Entry of International Application No. PCT/FR2013/051971, filed on Aug. 27, 2013, which claims priority to French Patent Application Serial No. 1259035, filed on Sep. 26, 2012, both of which are incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The present invention relates to the field of brushless electromagnetic motors, and more especially means for electrically connecting such motors. The invention more particularly aims at motors having a very compact thickness, i.e. when the diameter to height ratio must be optimized (typically a section of less than 50 mm). Brushless electromagnetic motors are provided with assemblies of electric excitation coils generally so configured as to provide a polyphase supply. In the case of three-phase motors, three coils 3X are thus to be connected, if X is the number of coils per phase, and connected in series or in parallel, with a star or a triangle configuration. 
     BACKGROUND 
     Solutions are known in the prior art, on the one hand to connect the coils together and on the other hand to provide the 3 connections required for supplying the 3 phases. For example, the patent EP1677404 discloses a small-sized motor for electric power steering, wherein the field coil flange can be easily executed while saving space. Multi-phase stator coils mounted in a stator core are connected per phase by connecting rings with the coil ends of the stator coils. A bus bar BB supplied with electric power from the outside is stacked on the connecting rings CR in the axial direction of the motor and is electrically connected to the connecting rings CR. 
     This document of the prior art does not disclose a coil body having two connection slots. It has no coplanar output track making it possible to obtain the simple and direct connection with the coils. As mentioned in paragraph [0102] of this document, it can be noted that a “bus bar” is provided, which is connected to the “connecting rings” which are, in turn, connected to the coils carried by bodies (which appear as not referenced in DI but which are clearly visible). 
     The present invention relates to a connector technology solution wherein the output tracks are directly connected to the coils through the coil body and such tracks are indexed relative to said bodies. This document thus provides a solution that uses at least one more part. The coil body is not used in the prior art since “connecting rings” are used for hooking the coil connections. 
     U.S. patent application publication no. 2007/278875 discloses a connection system consisting of a coil, a coil body, a first “conductor plate” and a second “conductor plate” which acts as the output. A large number of parts are thus required. In addition, the end of the output track is not folded back so as to provide an axial connection since the wire axially goes out so as to achieve a perpendicular connection (refer to FIG. 2 in D2, to the elements 24b which clamp the wire shown as axially going out). This document goes against the notions of flatness and simplicity that are aimed at by the present invention. 
     The patent DE20200900415 is not relevant either: as can be seen in FIG. 6 in D3, an “insulating ring” 42, used as a coil which receives the “bus bar” 44, 46, 48 is provided. The coil wires are then hooked to the “hook” 92W, 94W as shown in FIG. 1. 
     Therefore, no coil body having the shape of a slot complementary to that of the output track is present. No coplanar output is mentioned as having to be provided for, either, in this document. The proposed solution does not provide the advantages of a simplified connector technology and a limited number of parts. 
     As regards the document EP1727261, it can clearly be seen in the FIGS. 4, 7, 17 that the output tracks are not coplanar. This is the first noticeable difference. Then, when examining FIG. 6 more thoroughly, it can be seen (and read in paragraph [0020]) that the coil bodies (the “insulation ends” 10) have a “receiving chamber” 38 intended to receive the Insulation Displacement Contact 40 which is thus the part used to strip the wire. The output connector technology is provided axially by the “terminal contact” 50 that comes in the “bridge-like” portion 16a. 
     The reverse is true in the present document, since the wire is not bare in the coil bodies, but the output track achieves the stripping of the wire through its integrated terminal end of the IDC type. (Refer more particularly to FIG. 1 of our application, with the self-baring terminal ends 13 to 16). The elements of our claim thus cannot be found in D4 and the aims of simplicity and co-planarity are not aimed at. 
     U.S. Pat. No. 6,914,356 describes a solution for connecting tracks when several wires are provided. It may seem that we are straying from the object of the present invention. No coil body having a complementary shape wherein the output tracks are positioned is mentioned. No coplanar output either. 
     The patent WO03/001647 provides a set of coplanar tracks (although the output is axial) but the notion of slot in the body coil with a direct connection is not present. The notion of “the shape of said folded back end 15 13a, 14a, 15a, 16a being complementary to the shape of the connection slot 78” is not mentioned. 
     One drawback of the solutions of the prior art is their large sizes, especially in the axial direction, which does not make it possible to produce ultra-thin type engines of the “cake” type and more generally which increases the volume occupied by the motor. When the overall dimensions are limited by a restricted available space, the space occupied by the connector reduces the volume available for the rotor and the stator, and the power and the electromechanical qualities of the motor or the actuator are thus affected. 
     SUMMARY 
     The present invention aims at solving the above-mentioned problems by providing an advantageous connector engineering solution making it possible to bring the three electric phases of a motor with X coils per phase, connected in series or in parallel and delta- or star-connected to a connector having three terminal lugs, with a limited number of parts and small overall dimensions, both axially and transversally. For this purpose, the invention, according to its broadest sense, comprises, on the one hand, a brushless electric motor, and on the other hand a complementary connection assembly, with said brushless electromagnetic motor comprising a coiled stator assembly with P electric phases and X coils per phase, with each coil being carried by a body provided with two connection slots, characterized in that said connection assembly consisting of a first sub-assembly formed of W tracks cut in a conductive sheet, with said tracks forming W coplanar output tracks, with W being an integer between P and P+I, with each one of said W tracks terminating in at least one end folded back perpendicularly to the plane of said tracks, with the shape of said folded back end being complementary to the shape of the slot connection, with said tracks being joined by an insulating plastic material. 
     An electrical connection assembly for a brushless electromagnetic motor comprising a coiled stator assembly with P electric phases and X coils per phase, with each coil being carried by a body provided with two connection slots, characterized in that it consists of a first sub-assembly formed of W tracks cut in a conductive sheet, with said tracks forming W coplanar output tracks, with W being an integer between P and P+I, with each one of said W tracks terminating in at least at one end folded back perpendicularly to the plane of said tracks, with the shape of said folded back end being complementary to the shape of the connection slot, with said tracks being joined by an insulating plastic material. Advantageously, said tracks are initially connected by connecting bridges and then separated by cutting the connecting bridges upon overmolding with an insulating plastic material and are held by such overmolding. Still advantageously, the body is provided with slots which are used as supports for the coils whereon they are wound. 
     The invention also aims at providing a solution for connecting an assembly of Y signals (such as those emitted by Hall probes from an encoder used for detecting the rotor position of said motor from a printed circuit to same connector. For this purpose, the encoder is advantageously in the form of at least one circular magnetic track connected to the rotor and having alternating north-south magnetic poles associated with at least two Hall sensors positioned on a printed circuit in the axially adjacent direct vicinity of the magnetic track and detecting the evolution of the magnetic induction generated by the magnetic track. The electric management (supply and reading of signals) of the Hall probes is provided by an assembly of Y plugs which extend from the printed circuit and laterally go out of the motor toward a connector. 
     According to this particular embodiment, the connection assembly according to the invention further comprises a sub-assembly of connection tracks for connection to at least one position sensor. Advantageously, recesses are provided on the outer tracks to enable an optimized cutting in only one metal sheet. According to a particular embodiment, the tabs associated with the sensor have curved inner tracks. In a preferred implementation, said sub-assembly of tracks for the connection to at least one position sensor is co-molded upon molding the coil connecting tracks. 
     The invention also relates to a stator structure comprising a coiled stator assembly with P electric phases and X coils per phase, with each coil being carried by a body provided with two connection slots, and an electrical connection assembly according to the foregoing. Advantageously, said connector assembly is directly connected to said stator assembly. According to a particular embodiment, the surfaces of the connection slots perpendicular to the direction of insertion of the folded back end have pockets being complementary to the protrusions present on the overmolding, surrounding the corresponding folded back end. Said slots preferably have a configuration able to ensure a pre-centering upon the engagement of the folded back end into said connection slot. According to a particular embodiment, said configuration is able to ensure a pre-centering and consists of a chamfered bore. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood when reading the following description while referring to the appended drawings wherein: 
         FIG. 1  shows a first sub-assembly for connecting the coils, to form a connector according to the present invention; 
         FIG. 2  shows a second sub-assembly for connecting the sensors, to form a connector according to the present invention; 
         FIG. 3  shows a connector according to the present invention; 
         FIG. 4  shows a separate view of the stator assembly with a single coil; 
         FIG. 5  shows a separate view of the complete coiled stator assembly; 
         FIG. 6  shows a view of the stator and the connection assembly; 
         FIG. 7  shows a detail view of  FIG. 6 ; and 
         FIG. 8  shows the connection and overmolded motor assembly. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows the first connection sub-assembly  4  for producing a connector engineering assembly as claimed by the present patent. Such  FIG. 1  and the description thereof relates to a method of connection of the “triangle” type intended for an assembly of 6 electric coils forming three electric phases through the parallel connection of the coils two by two. The description of the connection sub-assembly  4  which is given below thus precisely refers to this “triangle/parallel” connection but the persons skilled in the art will be able to adapt the teachings below to any type of well-known connection (triangle or star and serial or parallel connection of the coils as described for example in patent FR2923951) without departing from the scope of the invention. 
     The first sub-assembly  4  is formed by three tracks  1  to  3  cut in a sheet of conductive, preferably non-magnetic, material such as brass, for example a copper-zinc alloy of the CuZn30 type which consists of 70% copper and 30% zinc. The cutting may be obtained by stamping, using a pure or silica-filled water jet, a laser or any other technique known to the persons skilled in the art. 
     The three tracks  1  to  3  are essentially coplanar (possibly except for the connection extensions  11 ,  21 ,  31 ), and have connection extensions parallel to each other  11 ,  21 ,  31  and extending parallel to an middle connection extension  31 . Such connection extensions  11 ,  21 ,  31  constitute the connection lugs making it possible to establish an electrical contact with a connector for supplying the coils (not shown here). Each track  1  to  3  is connected with four coils to form, two by two, one phase of power supply, according to a configuration known in the prior art. 
     The first track  1  has a curved portion  12  extending over about 220°, ending in a connecting extension  11 . The inner part of the curved portion  12  is extended by four radial shoes  13  to  16  directed towards the center of curvature of the curved portion  12 . Each one of such radial shoes  13  to  16  terminates in a self-baring end folded back over 90°  13   a  to  16   a  enabling the connection to the coils wires through a connection of the self-baring (or IDC, for Insulation Displacement Contact) type. The angular positioning of such radial shoes  13  to  16  and the corresponding folded back ends  13   a  to  16   a  is determined according to the position of the wires connecting the stator coils. 
     The curved portion  12  has a substantially constant radial thickness. However, it is provided with recesses  17  to  19  to enable cutting the three tracks  1 ,  2 ,  3  in a single sheet while reducing the waste of material. The depth of such recesses  17  to  19  and the angular extension thereof is so determined as to enable the cutting of the radial expansions of the complementary tracks  2 ,  3 . 
     The second track  2  has a curved portion  22  extending over about 220°, terminating in a connection extension  21 . The curved portion  22  is extended by four radial shoes  23  to  26  directed towards the center of curvature of the curved portion  22 . The curved portion  22  is arranged substantially symmetrically to the first curved portion  12  with respect to a central axis going through the central connection extension  31 . 
     Each one of such radial shoes  23 - 26  terminates in a self-baring end folded back over 90°  23   a  to  26   a  enabling the connection to the coils wires through a connection of the self-baring (or IDC, for Insulation Displacement Contact) type. Each end has a central plane perpendicular to a radial axis going through the center of the shoe. 
     The curved portion  22  has a first segment  22   a  having the same radius as the curved portion  12  of the first track  1 . Such first segment  22   a  extends over about 120° and then extends in a second segment  22   b  extending over about 100°, with a smaller radius. The two segments  22   a ,  22   b  are connected by a radial segment  22   c.    
     The curved portion  22  has a substantially constant radial thickness. However, it is provided with recesses  27 ,  28  to enable the cutting of the three tracks in one single sheet while reducing the waste of material. The depth of such recesses  27 ,  28  and the angular extension thereof are so determined as to enable the cutting of the radial shoes of the complementary tracks  2 ,  3 . 
     The third track  3  has a curved portion  32  extending over about 220°, terminating in a connection extension  31 . The curved portion  32  has a radius substantially identical to the radius of the second segment  22   b  of the second track  2 . The curved portion  32  is extended by four radial shoes  33  to  36  oriented in a direction opposite the center of curvature of the curved portion  32 . 
     Each one of such radial shoes  33 - 36  terminates in a self-baring end folded back over 90°  33   a  to  36   a  enabling the connection to the coils wires through a connection of the self-baring (or IDC, for Insulation Displacement Contact) type. The tracks are thus cut in one single sheet as demonstrated by the bridges  9 ,  10  shown in this Figure but which are cut after completion of the sub-assembly  4  to isolate the tracks from one another. 
       FIG. 2  shows a second sub-assembly  40  for the connection of a position encoder, for example implementing Hall probes. It consists of a converging bundle of five connecting tracks  41  to  45  supported by two insulating plates  46 ,  47 . Such tracks  41  to  45  are intended to be connected to an external circuit managing the supply and reading of the signals transmitted over such tracks  41  to  45 , namely the signals of the position encoder, e.g. as Hall probes. For example, with three Hall sensors, the five tracks  41  to  45  enable the connection to a (common) ground, a (common) power supply and three sensor signals (i.e. five connections are thus required indeed). The end of each track  41  to  45  extends perpendicularly to connecting means, for example to one end  51  to  55  having a “needle eye” of the Press-Fit (trade name) type. 
     Both assemblies  4 ,  40  are overmolded to form a connector enabling to provide both the mechanical and electrical connections, through a system shown in  FIG. 3 . The overmolding  56  holds the two subassemblies  4 ,  40  together. One of the objects of the invention is also to make it possible to enable a different angular indexing of the two sub-assemblies  4 ,  40  according to the relative position of the output connectors—not shown—(for supplying the coils on the one hand and managing the Hall probes on the other hand). The overmolding  56  has protrusions  57  having a non limiting shape of a pin, intended to enable the indexing of the overmolded assembly on the coiled stator  60 . 
     The inner end of the second sub-assembly  40  is made integral with a printed circuit board  80  by means of a Press-fit fixing or by welding the ends  51  to  56 . The printed circuit  80  additionally carries the Hall sensors  81  intended to detect the position of the motor rotor (not shown). 
     The stator  60  shown in  FIG. 4  consists of a stack of soft iron plates  61  having six wide radial teeth  62  to  67  intended to receive electric coils. Only one coil  62   a  is shown here for clarity. The stator  60  also has intermediate teeth  68  to  73  which are narrower than the wide teeth  62  to  67 . All the teeth extend radially from a peripheral ring  74 . Such stator  60  is consistent with the one disclosed in the patent FR2899396 but in no way limits the scope of the present invention which is globally intended to enable the connection of all types of topologies of brushless motors, the teeth of which extend radially. 
     Each wide tooth  62  to  67  carries a coil  75  which is positioned on a coil body  76 . Such coil bodies  76  have, on the one hand, pockets  77  intended to enable the indexing of the sub-assemblies  4 ,  40  overmolded on the coiled stator  60  and, on the other hand, slots  78  intended to enable the electrical connection. The terminal end of an insulated electric wire, which will be connected through the self-baring folded back ends of the tracks  1 ,  2 ,  3 , is positioned in these slots  78 . These slots have insertion pockets opening in substantially rectangular cavities having two longitudinal large faces parallel to a central longitudinal plane. Such longitudinal central plane and the two large faces are perpendicular to a radial axis. 
     The pockets  77  may have various shapes and locations on the coil bodies  76  but must be complementary in shape with the protrusions  57  present on the overmolding  56 . Advantageously, the pockets  77  may be chamfered to accommodate a tolerance in the mounting of the overmolding  56  on the coil bodies  76 . 
       FIG. 5  shows the coiled stator assembly  60  wherein each wide tooth carries an electric coil wound around a coil body which has pockets and slots intended to receive the sub-assemblies  4 ,  40  for the mechanical indexing and the electrical connection. The first connection sub-assembly  4  is applied to the front face of the stator  60  to provide the mechanical connection of the assembly via the indexing of the overmolding  56  with the pockets  62   c  to  67   c , as shown in  FIG. 6 . This tolerant indexing makes it possible to position the self-baring folded back ends  13   a  to  16   a ,  23   a  to  26   a  and  33   a  to  36   a  of the first sub-assembly  4  and enables the electrical connection within the slots  78  of the coil bodies  76 . 
       FIG. 7  shows a detail view of  FIG. 7  (as per the dotted line in  FIG. 6 ) wherein the electrical connection provided through the folded back end  13   a  in the slot  78  and permitted by the mechanical indexing of the overmolding  56  with the protrusion  57  which engages in the pocket  77  may be better appreciated.  FIG. 8  shows the connection assembly after the overmolding  84  of the assembly wherein the two sub-assemblies  4 ,  40  enable the electrical connection of the coils of the motor and the position sensor through the two female connectors of the motor  82  and the sensor  83  complementary to the male connectors (not shown) in the application. The product thus formed ensures safe electrical connections using a minimum number of parts within a limited axial space.