Patent Publication Number: US-2021167642-A1

Title: Stator assembly for electric machine

Description:
The present invention concerns the domain of stator assemblies designed to be fitted to an electric machine, and more specifically stator assemblies designed to be fitted to an electric traction machine of an electric-drive or hybrid-electric-drive motor vehicle. 
     Electric machines, typically designed to be fitted to a power unit of an electric-drive or hybrid-electric-drive motor vehicle, include a stator built into a housing. 
     Building the stator into the housing in this manner causes the stator to be cantilevered within the housing, which results in the appearance of very-high-energy, low-frequency modes of vibration. In the case of an electric traction machine of a motor vehicle, a mode of torsion of the stator of approximately 650 Hz typically appears about the axis of the electric machine. The torque delivered by the electric machine contains a certain number of harmonics that significantly excite these modes and cause significant vibrations. This has a negative effect on the acoustic and vibratory reliability of the stator assembly, i.e. the mechanical resistance of the assembly is jeopardized when operating in these modes of vibration and the vibrations caused generate an acoustic noise that is uncomfortable for the occupants of the vehicle. An embedding link between the housing and the stator with lower torsional flexibility is therefore required. 
     Document JPS649435 discloses a cantilevered stator fastened in a stator housing using threaded stems. A centering ring seal facilitates assembly of the stator and limits the vibrations inherent in faulty centering and screwing dispersion of the threaded stems, but cannot limit the vibrations caused by modes of torsion of the stator itself. 
     In view of the foregoing, the invention is intended to propose a stator assembly that overcomes the aforementioned drawbacks. 
     More specifically, the invention is intended to increase the stiffness of the embedding link between the stator and the housing in order to improve the acoustic and vibratory reliability of the stator assembly. 
     For this purpose, a stator assembly is proposed for an electric machine comprising a first housing portion, a second housing portion, a stator body inserted into at least the first housing portion, linking means for rotatably linking the stator body to the first housing portion, first fastening means for fastening the stator body to the first housing portion, and second fastening means for fastening the housing portions to one another. 
     According to one of the general features thereof, this assembly comprises a ring seal inserted axially between the stator body and the first fastening means as well as between said two housing portions. 
     Including such a ring seal makes it possible to use a single part to create a seal between the inside and the outside of the housing and to increase the stiffness of the embedding link between the stator and the housing. Being a stiffness increase, the ring seal thus arranged works flat and provides very high stiffness in the plane thereof. This enhances the acoustic and vibratory reliability of the stator assembly. 
     According to a specific embodiment, the ring seal comprises an inner radial portion that is interposed axially between the stator body and the first fastening means, and an outer radial portion that is interposed axially between the housing portions. 
     The ring seal thus arranged is rigidly held by the housing. This enables the ring seal to further increase the stiffness of the embedding link between the stator and the housing. 
     Advantageously, the inner radial portion admits a plane of symmetry perpendicular to the axial direction, the outer radial portion admitting a plane of symmetry perpendicular to the axial direction, the axial offset between the plane of symmetry of the inner radial portion and the plane of symmetry of the outer radial portion being less than 3 mm. 
     Such a limitation of the axial offset enables the bearing plane of the ring seal on the stator to be brought closer to the bearing plane of the ring seal on the housing portions. This maximizes participation of the ring seal in increasing the stiffness of the embedding link. 
     Advantageously, the axial thickness of the inner radial portion and/or the outer radial portion is between 0.25 mm and 0.8 mm. 
     In one embodiment, the first housing portion has a cylindrical cavity, the stator body being inserted into the cylindrical cavity, the linking means having an axial rectilinear rib projecting radially outwards from the stator body and an axial rectilinear slot formed in the first housing portion and extending radially outwards from the cylindrical cavity, the rib being seated in the slot. 
     Advantageously, the assembly includes a first axial through-orifice formed in the ring seal, a second axial through-orifice formed in the rib and a third axial orifice formed in the first housing portion in axial alignment with the slot, the third orifice having a thread, the assembly comprising a threaded pin passing through the first orifice and the second orifice and cooperating with the thread of the third orifice. 
     The use of a threaded pin passing through the first orifice and the second orifice and cooperating with the thread of the third orifice enables the ring seal, stator and first housing portion to be fastened solidly. 
     A washer may also be associated with the pin, the pin having a head and the washer being interposed axially between the stator body and the head. 
     Such a washer increases torsional and compression strength when tightening the pin. 
     Preferably, the second fastening means comprise a first axial through-bore formed in the second housing portion, a second axial bore formed in the first housing portion and a screw, the second bore having a thread, the screw passing through the first bore and cooperating with the thread of the second bore. 
     The use of a screw passing through the first bore and cooperating with the thread of the second bore enables the housing portions to be fastened solidly. 
     In one embodiment, the ring seal is at least partially made of steel sheet, preferably steel sheet with a high elastic limit. 
     The seal made of steel sheet significantly enhances the stiffness of the embedding link between the stator and the housing, in particular with steel sheet with a high elastic limit. 
     The limited thickness of the seal helps to compensate for the geometric tolerances of the parts making up the stator assembly, limiting the stresses generated. 
     According to another aspect, an electric machine for a motor vehicle including a stator assembly as defined above is proposed. 
    
    
     
       Other objectives, characteristics and advantages of the invention are set out in the description below, given purely by way of non-limiting example and with reference to the attached drawings, in which: 
         FIG. 1  is a radial view of a stator assembly according to a first embodiment of the invention, 
         FIG. 2  is an axial cross-section view of the assembly in  FIG. 1 , 
         FIG. 3  is an exploded perspective view of the elements making up the assembly in  FIGS. 1 and 2 , and 
         FIG. 4  is an axial cross-section view of an assembly according to a second embodiment of the invention. 
     
    
    
       FIGS. 1 to 3  are schematic views of a stator assembly  2  designed to be fitted to an electric machine (not shown). In this case, the electric machine fitted with the assembly  2  is an electric traction machine of an electric-drive or hybrid-electric-drive motor vehicle. 
     The assembly  2  notably comprises a first housing portion  4 , shown in  FIGS. 2 and 3 . The portion  4  is axisymmetric about an axis of symmetry  6 . A direct orthonormal vector base  8  is attached to the portion  4 . The base  8  comprises a vector x → , a vector y →  and a vector z → . The vector z →  is parallel to the axis  6 . 
     In the present application, and unless otherwise specified, the terms “axial”, “axially”, “radial”, “radially” and “tangential” shall be understood to relate to the axis  6 . Furthermore, the term “cylindrical” shall be understood according to its conventional definition, i.e. a cylindrical surface is a surface comprising straight lines in a given direction meeting a given curve. 
     The first portion  4  comprises a main body  10 . The body  10  is cylindrical with a circular axial section about the axis  6 . The body  10  extends radially between an outer cylindrical surface  12  and an inner cylindrical surface  14 . The surfaces  12  and  14  are cylindrical with a circular axial section about the axis  6  and diameters d 12  and d 14  respectively. 
     The portion  4  has a back wall  16 . The wall  16  extends axially between an outer axial surface  18  and an inner axial surface  20 . The surfaces  18  and  20  are flat and perpendicular to the vector z → . The surfaces  18 ,  20  extend the surfaces  12 ,  14  respectively. The wall  16  has a through-opening  22 . The opening  22  is cylindrical with a circular axial section about the axis  6  and of diameter d 22 . The opening  22  is designed to receive a rotor shaft (not shown). 
     The portion  4  has four radial projections  24  spaced apart regularly about the circumference of the surface  12 . The projections  24  are cylindrical relative to the direction of the vector z → . The projections  24  are substantially identical to one another. 
     The portion  4  has four radial projections  26  spaced apart regularly about the circumference of the surface  12 . The projections  26  are axially aligned with the projections  24 . The projections  24  are positioned axially between the wall  16  and the projections  26 . The projections  26  are cylindrical relative to the direction of the vector z → . The thickness of the projections  26  in the radial direction is strictly greater than the thickness of the projections  24  in the radial direction. The projections  26  are substantially identical to one another. 
     The portion  4  has four axial rectilinear slots  28 . The slots  28  are cylindrical relative to the direction of the vector z → . The slots  28  are spaced apart regularly about the circumference of the surface  14 . The slots  28  extend radially outwards from the surface  14  to form internal grooves in the surface  14 . The slots  28  are radially and inwardly aligned with the projections  24  and  26  respectively. 
     The portion  4  has a collar  30  shown in  FIG. 3 . The collar  30  extends radially outwards from the surface  12 . The collar  30  is cylindrical about the direction of the vector z → . The projections  26  are positioned axially between the projections  24  and the collar  30 . The collar  30  is delimited axially by an outer axial surface  31  opposite the projections  26 . As such, the portion  4  extends axially between the surfaces  18  and  31   
     Overall, the collar  30  is radially delimited by an outer cylindrical surface  32 . The surface  32  is cylindrical with a circular axial section about the axis  6  and of diameter d 32 . Locally, the collar  30  has twelve radial flanges  34 . The flanges  34  are cylindrical about the direction of the vector z → . The flanges  34  are spaced apart regularly about the circumference of the surface  32 . Also locally, the collar  30  has four radial flanges  36 . The flanges  36  are thicker than the flanges  34 . The flanges  36  are spaced apart regularly about the circumference of the cylindrical surface  32 . More specifically, the flanges  36  are axially aligned with the projections  24  and  26 . Thus, each flange  36  extends in the tangential direction between two adjacent flanges  34 . 
     With reference to  FIGS. 1 to 3 , the assembly  2  has a second housing portion  38 . The portion  38  is axisymmetric about the axis  6 . When assembled, the portions  4  and  38  form a housing for the electric machine. 
     The portion  38  comprises a main body  40  that is cylindrical about the axis  6 . The body  40  extends radially between an outer cylindrical surface  42  and an inner cylindrical surface  44 . The surfaces  42 ,  44  are respectively cylindrical with a circular axial section about the axis  6  and of diameters d 42  and d 44  respectively. The diameters d 42  and d 44  are respectively equal to the diameters d 12  and d 14 : 
     
       
         
           
             { 
             
               
                 
                   
                     
                       
                         d 
                         12 
                       
                       = 
                       
                         
                           d 
                           42 
                         
                         ± 
                         
                           1 
                            
                           mm 
                         
                       
                     
                   
                 
                 
                   
                     
                       
                         d 
                         14 
                       
                       = 
                       
                         
                           d 
                           44 
                         
                         ± 
                         
                           1 
                            
                           mm 
                         
                       
                     
                   
                 
               
                 
             
           
         
       
     
     The portion  38  has a back wall  46  extending axially between an inner axial surface  48  and an outer axial surface  50 . The surfaces  42 ,  44  are connected to the surfaces  50 ,  48  respectively. 
     The wall  46  has a cylindrical through-opening  52 . The opening  52  is cylindrical with a circular axial section about the axis  6  and of diameter d 52 , which is substantially equal to the diameter d 22 . Like the opening  22 , the opening  52  is designed to receive a rotor shaft (not shown). 
     The portion  38  has a collar  54 . The collar  54  is cylindrical about the direction of the vector z → . Overall, the collar  54  is radially delimited by an outer cylindrical surface  56 . The surface  56  is cylindrical with a circular axial section about the axis  6  and of diameter d 56 . The diameter d 55  is substantially equal to the diameter d 32 . Locally, the collar  54  has twelve relatively thin radial flanges  58  and four relatively thick radial flanges  60 . The flanges  58 ,  60  are axially aligned with the flanges  36 ,  34  respectively. As such, the collar  54  is substantially identical to the collar  30 . 
     The collar  54  extends axially between a proximal front surface  62  and a distal front surface  64  (not shown in the figures). The surfaces  62  and  64  are flat and perpendicular to the vector z → . As such, the portion  38  extends axially between the surfaces  50  and  64 . Furthermore, the surfaces  64  and  31  form seam sidewalks designed to bear directly or indirectly against one another in order to form a sealed seat for a stator seated in the housing. 
     The portion  38  has four axial rectilinear slots  61 , shown in  FIG. 2 . The slots  61  are axially aligned with the slots  34 . The axial cross section of the slots  61  is substantially identical to the axial cross section of the slots  34 . Thus, the slots  61  extend radially inwards from the surface  44  to form internal grooves in the surface  44 . 
     As shown in  FIG. 2 , the portion  4  includes a cavity  66 . The cavity  66  is cylindrical in relation to the direction of the vector z → . The cavity  66  extends axially between the surfaces  20  and  31 . The cavity  66  is delimited radially and externally by the surface  14  and the surfaces delimiting the slots  28 . 
     The portion  38  includes a cylindrical cavity  68 . The cavity  68  extends axially between the surfaces  64  and  48 . The cavity  68  is radially delimited by the surface  44  and the inner surface of the slots  61 . 
     The assembly  2  includes a stator  70 . The stator  70  notably comprises a stator body  72  and a stator winding  74 . 
     The stator body  72  is cylindrical and axisymmetric about the axis  6 . Overall, the stator body  72  extends radially between an outer cylindrical surface  78  and an inner cylindrical surface  79 . The surfaces  78  and  79  are cylindrical with a circular axial section about the axis  6 . The diameter d 78  of the circular axial section of the surface  78  is slightly less than the diameter d 14 . 
     Locally, the stator body  72  has four ribs  80 . The ribs  80  are rectilinear in the direction of the vector z → . The ribs  80  are spaced apart regularly about the circumference of the surface  78 . The ribs  80  extend radially outwards from the surface  78 . The ribs  80  extend along the entire axial length of the stator body  72 . The thickness of the ribs  80  is slightly less than the depth of the slots  28 . 
     The stator body  72  extends axially between a front surface  82  and a front surface  84 . The surfaces  82  and  84  are flat and perpendicular to the vector z → . 
     The assembly  2  has a ring seal  86 . The seal  86  is cylindrical and axisymmetric about the axis  6 . The seal  86  is intended to seal the cavities  66  and  68  from the outside of the housing and to enhance the stiffness of the embedding link between the elements  4 ,  38  and  72 . 
     The seal  86  is made of steel sheet with a high elastic limit. For example, the seal  86  can be made of the steels in the table below: 
     
       
         
           
               
               
               
             
               
                   
               
               
                 European standard 
                 Standard Afnor NF 
                 American standard 
               
               
                 EN 10027 
                 A 35573 
                 AISI 
               
               
                   
               
             
            
               
                 X6Cr17 1.4016 
                 Z8C17 
                 430 
               
               
                 X12CrMoS17 
                 Z10CF17 
                   430 F 
               
               
                 X5CrNi18-101.4301 
                 Z7CN18-09 
                 304 
               
               
                 X5CrNiMo18-101.4401 
                 z6CND17-11 
                 316 
               
               
                   
               
            
           
         
       
     
     The seal  86  is substantially flat and perpendicular to the vector z → . The seal  86  is delimited radially by an inner cylindrical surface (not referenced) with a circular axial section about the axis  6  and of diameter d 86i . Overall, the seal  86  is delimited radially by an outer cylindrical surface (not referenced) with a circular axial section about the axis  6  and of diameter d 86e . The diameter d 86i  is strictly less than the diameter d 78 . The diameter d 86e  is strictly greater than the diameter d 14  and preferably slightly less than the diameter d 12 . More specifically, in the example illustrated: 
     
       
         
           
             { 
             
               
                 
                   
                     
                       
                         
                           d 
                           
                             86 
                              
                             i 
                           
                         
                         = 
                         
                           
                             
                               9 
                               10 
                             
                             · 
                             
                               d 
                               78 
                             
                           
                           ± 
                           
                             1 
                              
                             % 
                           
                         
                       
                        
                       
                           
                       
                     
                   
                 
                 
                   
                     
                       
                         d 
                         
                           86 
                            
                           e 
                         
                       
                       = 
                       
                         
                           
                             
                               
                                 d 
                                 14 
                               
                               · 
                               9. 
                             
                              
                             
                               d 
                               12 
                             
                           
                           10 
                         
                         ± 
                         
                           1 
                            
                           % 
                         
                       
                     
                   
                 
               
                 
             
           
         
       
     
     Locally, the seal  86  is extended radially by four lugs  87 . The lugs  87  are spaced apart regularly about the circumference of the outer surface of the seal  86 . The radial thickness of the lugs  87  is substantially equal to the radial thickness of the flanges  36 . 
     The seal  86  is split into an inner radial portion  88  and an outer radial portion  90 . The limit between the portions  88  and  90  corresponds to the axial projection of the stator body  72  on to the flat surface of the seal  86 . In other words, the portion  88  has a portion positioned between the two cylinders of revolution about the axis  6  of diameter d 86i  and d 78 . Furthermore, the portion  88  has the four portions of the seal  86 , which are axially aligned with the four ribs  80  respectively. The portion  90  corresponds to the remainder of the seal  86 . 
     The portions  88  and  90  admit respectively the planes of symmetry P symmetry_88  and P symmetry_90  (not shown). The planes P symmetry_88  and P symmetry_90  are perpendicular to the vector z →  and positioned in the middle of the axial thickness of the portions  88  and  90 . In the first embodiment, the planes P symmetry_88  and P symmetry_90  are the same. The thickness of the seal  86  is between 0.25 mm and 0.8 mm. 
     The seal  86  has a rib  92  on one of the axial surfaces thereof. The rib  92  extends about the entire circumference of the axial surface of the seal  86 . The rib  92  is formed on the outer radial portion  90 . In a radial projection, the rib  92  is positioned at a distance l 92  from the outer radial limit of the seal  86 , the distance l 92  being constant. In other words, the rib as a whole forms a circle about the axis  6  of diameter d 92  greater than d 14 . Locally, the rib  92  moves away from the axis  6  relative to this circle, the gap varying from zero to a maximum value slightly greater than the radial depth of the slot  28 . As such, the rib  92  can be in full contact with the surface  64  or with the surface  31 , as a function of the orientation of the seal  86 . 
     With reference to  FIG. 3 , the portion  4  includes twelve axial bores  94 . The bores  94  are blind. The bores  94  are cylindrical and have a circular section about an axis parallel to the vector z →  and are of diameter d 94 . The bores  94  are threaded. The twelve bores  94  are formed respectively in the twelve flanges  34 . 
     The portion  38  has twelve axial bores  96 . The bores  96  are cylindrical and have a circular axial section about an axis parallel to the vector z →  and are of diameter d 96 . The bores  96  are through-bores and are threaded identically to the bores  94 . The twelve bores  96  are formed respectively in the twelve flanges  58 . The diameters d 94  and d 96  are substantially equal. 
       |   d   94   =d   96 ±1%   
     The seal  86  has four axial orifices  98 . The orifices  98  are cylindrical and have a circular axial section about an axis parallel to the vector z →  and are of diameter d 98 . The orifices  98  are radially and inwardly aligned with the lugs  87 . 
     The stator body  72  has four axial orifices  100 . The axial orifices  100  are cylindrical and have a circular axial section about an axis parallel to the vector z →  and are of diameter d 100 . The four orifices  100  are respectively formed in the four ribs  80 . 
     With reference to  FIG. 2 , the portion  4  includes four axial orifices  102 . The orifices  102  are blind and threaded. The orifices  102  are cylindrical and have a circular axial section about an axis parallel to the vector z →  and are of diameter d 102 . The four orifices  102  are respectively formed in the four projections  24 . The diameters d 98 , d 100  and d 102  are substantially equal. 
     With reference to  FIG. 3 , the assembly  2  has four threaded pins  104 . Each pin  104  has a head  106 , an unthreaded portion  108  and a threaded portion  110 . The portion  108  is positioned axially between the head  106  and the portion  110 . The portions  108  and  110  are cylindrical with a circular axial section of diameter d 104  that is slightly less than the diameter d 98 . The thread of the portion  110  is designed to cooperate with the thread of the orifices  102 . 
     Four washers  112  are respectively associated with the four pins  104 . The internal diameter d 112i  of the washers  112  is slightly greater than the diameter d 104 . The outer radius r 112e  of the washers  112  is strictly less than the minimum distance between the axis of an orifice  98  and the rib  92 . 
     The washers  112  are preferably made of non-magnetic material. For example, one of the steels in the table below can be used to make the washers  112 : 
     
       
         
           
               
               
               
             
               
                   
               
               
                 European standard 
                 Standard Afnor NF 
                 American standard 
               
               
                 EN 10027 
                 A 35573 
                 AISI 
               
               
                   
               
             
            
               
                 X5CrNi18-101.4301 
                 Z7CN18-09 
                 304 
               
               
                   
               
            
           
         
       
     
     The assembly  2  has twelve screws  114 . Each screw  114  comprises a head  116  and a threaded stem  118 . The diameter d 118  and the thread of the stem  118  are designed to cooperate with the diameters d 96  and d 94  and the threads of the bores  96  and  94 . 
     The assembly  2  can be assembled as follows: 
     Firstly, the stator  70  is inserted into the cavity  66 . More specifically, the stator body  72  is fully seated in the cavity  66 , while a portion of the winding  74  projects axially out of the cavity  66 . The ribs  80  enter the slots  28 . 
     The seal  86  is then arranged against the surface  82 . In this layout, the portion  88  bears against the surface  82  and the portion  90  bears axially against the surface  31 . 
     The pins  104  are then inserted into and pivoted in the orifices  98 ,  100  and  102 . This causes the thread of the portion  110  to cooperate with the thread of the orifice  102 . When the pins  104  are tightened, the elements  4 ,  70  and  86  form a rigid assembly. 
     In this embodiment, the seal  86  is arranged in the position shown in  FIG. 3 , i.e. with the rib  92  opposite the elements  4  and  70 . The seal  86  can naturally be in a position in which the rib  92  is adjacent to the elements  4  and  70  without thereby moving outside the scope of the invention. In this case, the rib  92  is pressed axially against the surface  31 . 
     The portion  38  is then in contact with the portion  4  such that the surfaces  31  and  64  face one another axially. More specifically, the portion  38  is oriented in relation to the portion  4  such that the flanges  60  are arranged to face the flanges  26 . In this layout, the surface  64  is in direct contact with the rib  92 . 
     The screws  114  are then tightened. This causes the thread of the stems  118  to cooperate with the thread of the bores  96  and  94 . When the screws  114  are tightened, the elements  4 ,  70 ,  86  and  38  form a rigid assembly. The surface  64  axially compresses the rib  92  to create a seal between an internal space and an outer space of the housing. The seal  86  is compressed between the seam sidewalks  31  and  64  and bears axially against the stator body  72 . Fastening the stator body  72  using the pins  104  and making the seal  86  from steel sheet with a high elastic limit and low thickness help to increase the stiffness of the embedding link between the stator body  72  and the housing. 
     Although in the example shown in  FIGS. 1 to 3 , the assembly  2  has four subassemblies each comprising a projection  24 , a projection  26 , a flange  36 , a lug  87 , a flange  60 , an orifice  98 , an orifice  100 , an orifice  102 , a washer  112  and a pin  104 , it is naturally possible to select a different number of such subassemblies without thereby moving outside the scope of the invention. It is also possible to select another number of subassemblies each having a flange  34 , a flange  58 , a bore  94 , a bore  96  and a screw  114  without thereby moving outside the scope of the invention. It is also possible to select another number of subassemblies each having a rib  80  and a slot  28  without thereby moving outside the scope of the invention. 
     Although in the example shown in  FIGS. 1 to 3 , only the orifice  102  is threaded, it is naturally possible for one of the orifices  98  and  100  to be threaded without thereby moving outside the scope of the invention. Equally, the bore  96  can be unthreaded. 
       FIG. 4  is a schematic representation of a stator assembly  120  according to a second embodiment of the invention. The same elements are indicated using the same reference signs. 
     The axial length of the stator body  72  of the assembly  120  is shorter than the axial length of the stator body  72  of the assembly  2 . The inner radial portion  88  is axially offset in relation to the outer radio portion  90 . The axial offset Δ between the planes P symmetry_88  and P symmetry_90  is substantially equal to the offset between the surfaces  31  and  82  when the stator body  72  is installed at the bottom of the cavity  66 . The offset α is preferably strictly less than 3 mm. 
     In this embodiment, the seal  86  has a cylindrical portion  122  in addition to the portions  88  and  90 . The portion  122  is cylindrical in relation to the direction of the vector z → . The axial section of the portion  122  corresponds to the axial projection of the stator body  72 . The axial thickness of the portion  122  is substantially equal to the offset Δ. 
     In this embodiment, this arrangement makes it possible to create the seal between the inner space and the outer space of the housing and to increase the stiffness of the embedding link, even where the stator body  72  is axially shorter than the portion  4 . 
     In the second embodiment, the seal  86  is designed to take account of a reduction in the axial length of the stator body  72 . However, it is naturally possible to adapt the seal  86  to take into account an increase in the axial length of the stator body  72  without thereby moving outside the scope of the invention. 
     Creating a seal between the inside and the outside of the housing facilitates aspiration of hydraulic fluid. This makes oil surges of the suction point less sensitive to inclines on account of the lesser displacement of hydraulic fluid. Increasing the stiffness of the embedding link between the housing and the stator body effectively absorbs vibrations that could appear in this link, thereby enhancing the acoustic and vibratory reliability of the stator assembly according to the invention.