Abstract:
An electronic actuator is made up of a polyphase brushless motor comprising a rotor provided with permanent magnets and secured to an output shaft, and a stator supporting coils and providing the magnetic drive of the rotor, a first electrical connection assembly powering the coils, said stator being built into a stator module made up of a material which coats the wound stator as well as the first electrical connection assembly. The rotor is built into a rotor module made up of a flange coating a bearing that guides the shaft of the rotor. The stator module and the rotor module have elements for indexing and for attachment relative to one another.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a National Phase Entry of International Patent Application Serial Number PCT/EP2015/079302, filed on Dec. 10, 2015, which claims priority to French Patent Application Serial No. 14/62289, filed on Dec. 11, 2014, both of which are incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates to the field of brushless type polyphase electric motors that have a series of permanent magnets interacting with a soft ferromagnetic stator supporting electric coils. The coils are supplied with a polyphase alternating current through an electronic switching provided by an electronic circuit. The invention more specifically proposes an actuator consisting of a motor and an electronic assembly integrated in a compact and simple manner in separate coated modules (for example by overmoulding a plastic, polymer or even metallic material) and then assembled. 
         [0003]    In the remainder of this text, the term “motor” is understood to mean all the elements (coil, soft ferromagnetic stator, permanent magnets and possible soft ferromagnetic yoke) of the magnetic circuit making it possible to produce the magnetic force and “actuator” means the entire engine, in its finalized version, associated with the electrical power supply elements of the engine and position sensing elements. 
       BACKGROUND 
       [0004]    There are many permanent magnet brushless polyphase electric motors such as those described in Patent EP0949747 or EP2002531, both by the Applicant. Motors of this type are composed of a wound stator assembly and a rotor assembly comprising a plurality of magnets. In order to ensure the electrical switching of the different phases of these motors, the generally chosen solution consists in using at least one Hall probe placed opposite the plurality of magnets or an auxiliary magnetized assembly dedicated to this switching. In order to embody an actuator, the Hall sensors, as well as the electronic circuit controlling them, and the electrical connector assembly of the motor phases must be assembled in an integral product which can be placed and used in any application (for example for Moving different valves, flaps or shafts in an internal combustion engine). 
         [0005]    There are various forms of embodiment in prior art solutions. For instance, some solutions consist in partially overmoulding the motor, most often only the stator is overmoulded. Patent Application PCT WO/2009/055625 relates to a stator assembly and to a method for producing a stator assembly. The stator assembly is overmoulded with a thermally conductive and electrically insulating polymer composition. The stator core of the stator assembly is coated with an adhesive component to allow better heat transfer to the interface of the stator core and the overmoulded coils. 
         [0006]    Patent application EP1677404 also discloses a motor for an electric power steering, where the connection of the coil can be easily embodied while saving space, and a method of manufacturing the engine. Stator coils are assembled into a stator core and connected per phase by connecting rings. Patent applications EP2781758, US2010/301691, WO2011159674 or US2008/023028 describe other exemplary embodiment of prior art. 
         [0007]    Prior art solutions have the disadvantage of a complicated assembly, requiring precise mechanical positioning of the stator parts in the housing and/or with respect to the rotor. During assembly, it is necessary to make multiple mechanical and electrical connections in order to ensure the connection of the coils to a wiring harness or connection elements with the electronic circuit, the electrical connectors and if necessary with a printed circuit. These different operations require high precision and are cause the fragility of the device. 
         [0008]    The overmoulding solutions known in the prior art do make it hard to ensure the coating of all the components of a stator structure and only partially avoid the problem of assembly and electrical connections. Specifically, in the solution proposed in Patent Application EP1677404, the wound stator and the connector technology do not form an encapsulated assembly, which leads to mechanical weaknesses. 
       SUMMARY 
       [0009]    This invention aims at remedying these drawbacks by proposing a device comprising a coated stator module insertable into the housing of a motor or an actuator in order to interact electromagnetically with a rotor and cooperating with a rotor module. The invention, in the widest sense of the term, relates to an electronic actuator made up of a polyphase brushless motor comprising a rotor provided with permanent magnets and secured to an output shaft, and a stator supporting coils and providing the magnetic drive of the rotor, a first electrical connector assembly powering the coils, said stator being built into a stator module made up of a material which coats the wound stator as well as the first electrical connector assembly. The invention is characterized in that the rotor is built into a rotor module made up of a flange coating a bearing that guides the shaft of the rotor, and in that the stator module and the rotor module have elements for indexing and for attachment relative to one another. 
         [0010]    The rotor module thus forms a first component integrating: 
         [0011]    the rotor consisting of a cylinder head on which the permanent magnets and the output shaft are mounted, 
         [0012]    a guide element, 
         [0013]    a flange ensuring the coating of this assembly. 
         [0014]    The stator module forms a second component integrating: 
         [0015]    the wound stator, 
         [0016]    a first electrical connector assembly, 
         [0017]    these elements being equally coated. 
         [0018]    The motor is thus made up of two complementary components that neither require an electrical connection nor fastening hardware. The connection is provided by the complementary configuration of the two coated components, each with an indexed complementary assembly interface to guarantee the precise relative positioning of both these components. 
         [0019]    A significant advantage of this coated modular embodiment is better management of the temperature of the electrical connection assemblies and of the printed circuit connecting them. Indeed, when the actuator operates at high temperature, the heat is confined to the level of the stator, which easily supports this thermal load, and is only weakly spread at the back of the actuator towards the electrical and electronic connection elements. It is thus possible to significantly limit the heating of the printed circuit with respect to the forms of embodiment of prior art. 
         [0020]    A major advantage of the invention and its modular embodiment is a significant reduction in the number of parts required for the embodiment of the actuator when compared to the forms of embodiment of prior art. Optionally, the stator module further comprises an electronic circuit equally coated to form a second Smart Component. 
         [0021]    Preferentially but non-exhaustively, the actuator comprises a second electrical connector assembly managing the supply and the signals of the sensing elements necessary for the switching of the various phases of the motor and the stator module coats the first and second electrical connector assembly. This second assembly is thus necessary when one wishes to control the engine thanks to an encoder assembly integrated in the engine. It is not necessary if the motor is to be driven in the sensorless mode. 
         [0022]    Preferentially, the stator assembly has a cavity adapted to receive the said rotor module. In one form of embodiment, the first and second electrical connection assemblies form a radial coated extension of the said stator module. In one form of embodiment, the first and second electrical connection assemblies form an axially coated extension of the said stator module. 
         [0023]    Preferentially, the flange has an external shape that is complementary to the receiving zone of the stator module in order to allow easy assembly. For instance, the said flange of the rotor module has centering pins adapted to engage in complementary housings formed on the stator module. 
         [0024]    In one particular form of embodiment, the stator module comprises a set of superimposed laminations with a plurality of teeth, at least part of which supports an electric coil, each of the said electrical coils having axially extending connecting lugs, said stator module further including a plurality of teeth for connecting a complementary connector, all of the components comprising the said wound sheet assembly, the said coil connecting lugs, and said connector lugs for joining-up a connector are coated with a material insulating plastic to form a monolithic block encompassing the outer surfaces of the said superimposed sheets. The inner surface of the said teeth of the stator plates can be made flush with the inner surface of the said monolithic block and the cavity made cylindrical and closed at its rear part by a moulded bottom. In this case, the said moulded bottom may comprise a ring for guiding the rotation axis of the rotor. 
         [0025]    According to a variant, the inside surface of the said teeth of the stator plates is included in the said monolithic block, the thickness of the encapsulating plastic material being less than the air gap between the outer cylindrical surface of the rotor and the cylindrical envelope defined by the surface of the stator teeth. The invention also relates to a magnetized rotor module formed by a coated sleeve comprising a bearing for guiding the rotor, the sleeve being surrounded by a collar capable of being fixed to a stator structure by welding or screwing or riveting. In a variant embodiment, the cavity is open and the actuator has a third module comprising a printed circuit and closing the actuator on the rear part. 
         [0026]    The invention also relates to a method for manufacturing a characterized magnetized rotor module in that it comprises the following steps: 
         [0027]    overmoulding of the front bearing to form the flange with its positioning and indexing pins, 
         [0028]    assembly of a stack of laminations on the rotor axis, 
         [0029]    bonding of the magnet(s) of the motor on the stack of laminations, 
         [0030]    assembly of the rear bearing on the axle comprising the bundle of laminations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The invention will be better understood on reading the following description, with reference to the attached drawings corresponding to non-exhaustive samples of embodiments, where: 
           [0032]      FIGS. 1 and 2  show the stator module wound with by means of electrical connection of the motor and of the sensing assembly; 
           [0033]      FIG. 3  shows the coated stator module; 
           [0034]      FIGS. 4 and 5  represent views of the cavity formed in the stator coated respectively before and after the insertion of the electronic circuit; 
           [0035]      FIGS. 6 and 7  represent views of the rotor module respectively in three-quarter view and in longitudinal section; 
           [0036]      FIGS. 8 and 9  represent views of the assembly of the coated stator and of the rotor module respectively before assembly and after assembly, in a first form of embodiment, called a “disc” mode; 
           [0037]      FIGS. 10 to 12  represent views of the assembly of the coated stator and of the rotor module respectively before assembly ( FIG. 10 ), in cross sectional view ( FIG. 11 ) and after assembly ( FIG. 12 ), in a second form of embodiment called “tubular” mode; 
           [0038]      FIGS. 13 and 14  represent views, respectively before assembly of the modules and after assembly of the modules, in a third form of embodiment in which the rotor module comes around the stator module; 
           [0039]      FIG. 15  shows a sectional view of the modes described in  FIGS. 13 and 14 ; 
           [0040]      FIGS. 16 and 17  represent sectional views, respectively of the rotor module and the stator module, of an alternative tubular embodiment; 
           [0041]      FIG. 18  is a sectional view of the engine assembled from the modules described in  FIGS. 16 and 17 ; and 
           [0042]      FIG. 19  shows a variant embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    The invention described relates to a rotary motor formed by assembling a rotor module and a stator module. The components of these modules are mechanically linked so as to be permanently fixed. 
         [0044]    The rotor module is permanently assembled. Similarly, the stator module is embedded in an insulating plastic material which only allows the electrical connector elements to protrude. These two modules are assembled by inserting the rotor module into a housing provided for this purpose in the stator module and joined together by screwing, welding or gluing. A third module may optionally close the actuator when the stator module has a cavity opening. 
         [0045]    In a first form of embodiment, an actuator according to the invention commonly comprises a motor with a stator  1  that has radially extending teeth, equipped with electric coils  2  carried by coil bodies  3  as shown in  FIG. 1 . In this example described, the motor is three-phase and as described in Application EP2002531, but the invention is in no way limited to this particular technology. 
         [0046]    A first connector assembly  6  is positioned on an end face of the stator  1  to ensure electrical connection of the coils  2 . The second connector assembly  7  is then positioned to manage (supply and output) the sensing elements (typically Hall effect probes) necessary for the operation of the brushless motor according to the teachings of the state of the on an outer surface of the first connector assembly  6  as shown in  FIG. 2 . The first connector assembly  6  is indexed on the stator  1  by means of guide cavities  4  provided in the coil bodies  3  for precise positioning. The electrical connection is ensured by inserting line terminations of the first connector assembly  6  in the notches  5  of the coil body  3 , for example by Insulation Displacement contact (IDC). 
         [0047]    In this example, there are three electric phases which are powered by three separate tracks  6   a ,  6   b ,  6   c . The tracks  6   a ,  6   b ,  6   c  extend radially and then laterally with respect to the stator, and are in the form of tracks with rectangular section. The tracks end in forked connection tabs (not shown) for connecting an electrical phase by IDC contact. This assembly is produced by cutting and folding a metal foil, for example bronze or a CuZn30-type copper alloy, and then overmoulded with an insulating resin  8  as shown in  FIG. 2 . 
         [0048]    The second connector assembly  7  shown in  FIG. 2  allows the connection of a set of signals—for example those of Hall probes belonging to an encoder for sensing the position of the rotor of the said motor from a printed circuit to the same connector. Here, five tracks  7   a  to  7   e  are used to enable the input and the evaluation of the signals of the Hall probes. This second assembly  7  is then positioned on the first coated assembly as shown in  FIG. 2 . This embodiment of the stator  1 , associated with the first  6  and second  7  connector assembly, is described more precisely in the Application FR 12/59035. 
         [0049]    The stator  1  as well as the first  6  and second  7  assemblies are coated together in an injection mould to form a closed monolithic part shown in  FIG. 3 . The coated assembly then constitutes the stator module  9 . 
         [0050]    The shape of this stator module  9  may vary depending on the final applications. In the example of  FIGS. 1 to 6 , this is a first embodiment known as a “disc” in the sense that the actuator produced has a larger dimension according to its diameter than its height. 
         [0051]    The overmould coating here covers all the components of the stator except for the ends of the various tracks  7   a  to  7   e  and  6   a  to  6   c  which protrude inside two openings  10  and  11 , to allow an electrical connection to an external socket or to an attached external electronic circuit. Inside this stator module  9 , the teeth of the stator  1  are either flush with the overmoulding or covered with a thin skin during overmoulding. This monolithic part forming the stator module  9  has an annular cavity  12  whose bottom is closed in this first embodiment of  FIG. 4 . The stator module  9  has three lateral protuberances  13  to  15  drilled to allow the actuator to be secured. The overmoulded stator module  9  is thus totally sealed and self-contained. 
         [0052]    The bottom of the cavity  12  allows the tabs  16   a  to  16   e  of the second connector assembly  7  to be protruded, i.e., the inner ends of the tracks  7   a  to  7   e . These tabs  16   a  to  16   e  connect to a disc-shaped electronic circuit  17 , which can be housed at the bottom of the cavity  12  as shown in  FIG. 5 . 
         [0053]    The stator module  9  enables, because of its shape, to receive a rotor module  18  shown in  FIGS. 6 and 7 . The rotor module  18  includes a flange  19  with radially extending centering lugs  20  to  24  and which also has a mechanical rigidity function. The flange  19  forms a ring  25  on the inside of the rotor module  18  which receives a guide element  28  guiding the axis  26  of the magnetic rotor  27 . The magnetic rotor  27  consists of an alternation of permanent magnets  29  to  38  of alternate polarities (North/South). 
         [0054]      FIG. 7  shows a sectional view of the rotor module  18  making it possible to better appreciate the relative positioning of the flange  19  and the bearing  25  for guiding the shaft  26 . The ferromagnetic cylinder head  41  can be seen on which the magnets  29 - 38  and the encoder magnet  40  are positioned, consisting of alternating magnetized polarities. This encoder magnet  40  serves in detecting the position of the rotor together with the sensing elements and the electronic circuit  17  at the bottom of the non-opening cavity  12  of the stator module  9 , facing this encoder magnet  40  when the stator  9  and rotor  18  modules are assembled. 
         [0055]      FIG. 8  shows the positioning of the rotor module  18  in the stator module  9  by insertion in axial displacement (relative to the actuator rotation axis), the indexing of the two modules by means of the lugs  20  to  24  which are housed in complementary housings  44  to  49  and then assembled by screwing, gluing, ultrasonic welding or any other known assembly method.  FIG. 9  shows a view of both assembled modules forming the actuator  39  in its finalized version. 
         [0056]      FIGS. 10, 11 and 12  represent a second embodiment of the actuator  39  in a so-called “tubular” shape, that is to say an actuator whose height dimension is greater than that of its diameter. In this variant, the actuator  39  drives a screw  42 . In this example, the stator module  9  locally has an electrical connection socket  43  extending radially with respect to the rotation axis of the actuator  39 . The rotor module  18  comprises a flange  19  receiving, just as the first embodiment, a housing for a guide element  28 . 
         [0057]      FIG. 11  shows a sectional view of the stator of this other variant embodiment. The rotor module  18  has an inner core formed by a stack of disc laminations  50  which are forcefully engaged on a shaft  26  and supporting permanent magnets ( 29 - 38 ) in the form of tiles. The stator  1  is fed by means of a connector assembly described in European Patent EP2212985 by the Applicant. The stator  1  receives a second connector assembly  7  for the positioning of a Hall probe. 
         [0058]    This assembly is overmoulded to form a monolithic part, with a main body  51  and a secondary body  52  whose longitudinal axis is perpendicular to that of the main body  51 . In the embodiments shown above, the rotor module  18  is indexed, based on the complementarity of the shapes of the modules, inside the stator module  9 . 
         [0059]      FIGS. 13 and 14  show a third embodiment where the rotor module  18  is fastened to the stator module  9  from the outside. The flange  19  of the rotor module  18  has in this case a diameter greater than that of the stator  1  of the stator module  9 .  FIG. 15  makes it possible to appreciate the detail of the elements that are found in this embodiment. The various elements pointed being identical in their function to those mentioned in the preceding modes. 
         [0060]    The invention is not limited to a motor that has a stator with radial teeth. It also applies to an engine whose stator has teeth extending parallel to the axis, with a disc rotor, or a linear motor. The variant embodiment of  FIGS. 10, 11 and 12  makes it possible to produce a so-called “tubular” version described above. 
         [0061]    It is possible to envisage an alternative embodiment in order to obtain a more compact set. This alternative is particularly described in  FIGS. 16 to 18 . This form of embodiment differs from the mode described in  FIG. 10  in that the rotor module  18  comprises a second, a guide element  28 ′ which is made secured to the shaft  26  after mounting the stack of laminations  50 . This embodiment makes it possible to mount two guide elements  28  and  28 ′ of smaller sizes and allows easier assembly in the stator module  9 . 
         [0062]    The rotor module  18  is typically made with the following steps: 
         [0063]    the front guide element  28  to form the flange with its positioning and indexing pins  20 , 
         [0064]    assembling the stack of laminations  50  on the rotor axis  26 , 
         [0065]    bonding of the magnet(s)  29  of the motor on the stack of laminations  50 , 
         [0066]    assembling the rear guide element  28 ′ on the shaft  26  comprising the stack of laminations  50 . 
         [0067]    In the example described, a sensor magnet  53  is then assembled with its support on the free end of the spindle (for example by forcing through or screwing). After the magnetization of the magnets of the motor and of the sensor in place, this assembly of the axle+stack of laminations+magnets of the motor+rear bearing+magnet sensor on its support is finally assembled to the overmoulded module formed from the rear guide element  28  and the flange  19 . The stator module  9  specifically has an internal opening cavity  12  which makes it possible to assemble the more easily formed rotor module  18  and to bring back a third module  56 , thereby closing the actuator on the rear part. 
         [0068]    After assembling both the stator  9  and rotor  18  modules, it is thus necessary to add a complementary electronic module comprising, in this example, the printed circuit  17  receiving the detection probe(s)  55  of the magnetic field sensor and a closure cap  54 . This embodiment has the advantage of enabling the integration of a printed circuit of larger size (than that shown in the embodiment of  FIGS. 10 and 11 ), so that it may also be possible to place an on-board electronic control circuit directly driving the phases of the engine. 
         [0069]      FIG. 19  shows an alternative embodiment of an actuator  39  according to the invention in which the stator module  9  accommodates an on-board electronic circuit that enables the motor control system management. This is called an “intelligent” or “smart” motor and the connector technology leaving the motor is simplified because there is no need to remove the electrical tabs of the second connector assembly  7  from the motor. Typical elements that can be found in this electronic circuit are: a switching logic management module  60 , one or more filtering capacitors  61 , a set of MosFet-type switching transistors  62  to control the supply of the various phases. These electronic elements are then positioned on the overmoulded stator module  9  and a lid (not shown) can be placed glued, welded, screwed or riveted to complete the motor.