Patent Publication Number: US-2021167656-A1

Title: Rotary electrical machine

Description:
TECHNICAL FIELD 
     The invention relates to a rotary electrical machine, in particular for a motor vehicle, wherein putting into place of the interconnector is simplified. 
     The invention has applications in the field of rotary electrical machines such as alternators or reversible machines which can operate as an electric generator or an electric motor. 
     PRIOR ART 
     In a known manner, rotary electrical machines comprise a stator and a rotor which is integral with a shaft. The rotor can be integral with a driving and/or driven shaft, and can belong to a rotary electrical machine in the form of an alternator, an electric motor, or a reversible machine of the alternator-starter type, which can operate in both modes. 
     The stator is fitted in a housing which is configured to rotate the shaft on bearings by means of roller bearings. The rotor is of the “rotor with claws” type, and comprises two magnet wheels which each have claws imbricated in one another in order to form the poles, and a core around which a rotor coil is wound. According to another example, the rotor comprises a body formed by a stack of metal plate sheets which are retained in the form of a set by means of an apstandriate securing system. The rotor comprises poles which are formed for example by permanent magnets accommodated in cavities provided in the magnetic mass of the rotor. Alternatively, in a so-called “projecting” poles architecture, the poles are formed by coils wound around arms of the rotor. 
     As represented in  FIGS. 1, 2 and 3 , the stator  100  comprises a body  110  constituted by a stack of thin metal plates forming a crown, the inner face of which is provided with notches  111  which are radially open towards the interior in order to receive phase windings  120 . These phase windings  120  pass through the notches  111  in the stator body and form a coil end  125 ,  126  on both sides of the stator body  110 . The phase windings  120  are polyphase windings, connected in the form of a star or a triangle, the phase input/outputs  123  of which are connected to an electrical control module. 
     The phase windings  120  are obtained from conductive elements in the farm of pins  121 . A pin  121  has two branches which are connected by a curved head, or collateral portion, and the intermediate straight portions, or central portions of which, are placed in two different notches which are offset from one another angularly by a predetermined angle. The heads of the pins  121  are twisted and form the upper coil end  125 , i.e. the coil end which is provided with the phase inputs/outputs, situated upstream from the winding. The free ends of the branches are connected to one another for example by welding, and are twisted in order to form the lower coil end  126 , i.e. the coil end downstream from the winding. 
     The pins  121  are connected to one another electrically. Two pins  121  of a single winding are connected to one another directly, for example by welding, Two phase windings  120  are connected to one another by means of inversion pins  130 , with each inversion pin connecting the final pin  121   a  of one of the windings electrically to the first pin  121   b  of the other winding, in general, the inversion pins  130  are located above the upper coil end, i.e. in the axial extension of the winding, such as to connect to one another two windings having respectively a first and a second pin which are positioned spaced from one another. 
     Each phase winding  120  comprises a phase output  124  and a connection point  122 . When the phase windings are connected in the form of a star, the connection point is a neutral point. When the phase windings are connected in the form of a triangle, the connection point is a point which makes it possible to connect two distinct windings in order to form the triangle connection. The winding of the stator thus comprises a plurality of connection points  122 , and a plurality of phase outputs  124  distributed along a periphery of the stator  100 . The connection points  122  of a single phase system must be connected together without creating an electrical short circuit with the phase outputs  124 , in order to guarantee a good electrical supply to the winding of the stator. For this purpose, the stator  100  generally comprises an electrical connection unit  140 , which connects the connection points  122  electrically to one another whilst avoiding the phase outputs  124 . A connection unit of this type generally has a complex form, and consequently a substantial size. 
     In the example of a stator represented in  FIG. 3 , the connection unit connects the neutral points  122  electrically to one another and goes around the phase outputs  124 . However, because of the complex form of this connection unit and the need to keep it spaced from the phase outputs, production of the stator requires precise putting into place of the connection unit above the coil end, and retention of the said unit in position throughout the duration of the process of welding of the neutral points  122 , which makes the production process difficult and problematic. 
     SUMMARY OF THE INVENTION 
     In order to respond to the above-described problems relating to the difficulties of production of the stators and of size of the connection units, the applicant is standosing a rotary electrical machine wherein the connection unit is partly over-moulded in an electrically insulating material. 
     According to a first aspect, the invention relates to a rotary electrical machine, in particular for a motor vehicle, comprising:
         a stator comprising a stator body and an electrical winding, the said electrical winding comprising a plurality of phase windings forming a coil end projecting from an axial end face of the stator body, each phase winding comprising an end forming a winding connection point; and   at least one electrical connection unit which is positioned in the extension of the stator, and comprises at least one electrically conductive element over-moulded in an electrically insulating material, and extending radially from the electrically insulating material, in order to form at least two connection outputs to which the connection points are connected.       

     A rotary electrical machine of this type has a size which is reduced in comparison with the machines according to the prior art. 
     According to one embodiment, the connection points are neutral points of the winding. 
     According to one embodiment, the electrical winding is a winding of the wave type. The said winding can for example be of the simple wave or distributed wave, or also simple wave type. A wave winding of this type is different from a winding of the concentric type, in that a single coil of a phase winding of a wave winding is inserted in a plurality of notches, such as to be wound around a plurality of teeth, and a coil of a phase winding of a winding of the concentric type for its part is wound around a single tooth. 
     According to one embodiment, the electrical winding comprises a plurality of electrical conductors which are connected to one another such as to form the plurality of phase windings. For example, each of the electrical conductors has the form of a “U” or an “I”. Reference is then made to a winding with conductive pins. 
     Advantageously, the connection unit is positioned at the top of the coil end. 
     According to some embodiments, the connection unit is supported on the coil end. These embodiments make it possible to limit the vibrations within the machine when it is rotating. 
     In some embodiments, in which the electrical winding comprises a plurality of electrical conductors connected to one another such as to form the plurality of phase windings, and inversion pins each connecting two distinct electrical conductors electrically, the connection unit is supported on at least one of the inversion pins. 
     These embodiments permit facilitated putting into place of the connection unit during the production of the machine. 
     The rotary electrical machine according to the invention can comprise one or a plurality of the following characteristics:
         the electrically insulating material forms a stability stand at one end of the connection unit at least.   a contact area formed by a contact between the connection output of the connection unit and the connection point of the associated winding extends on a plane parallel to the axis of the stator, and in particular on a plane comprising the said axis.   the connection output of the connection unit and the connection point of the associated winding are arranged such as to be in contact with one another in a circumferential direction, and in particular only in the said circumferential direction.   the connection outputs each comprise at least one connection area extending axially along a connection point and to which the said connection point is connected.   the connection outputs each comprise at least one connection area extending radially along a connection point, and to which the said connection point is connected.   the connection unit comprises a plurality of electrically conductive elements which are over-moulded in a single electrically insulating material, with ends of the electrically conductive elements forming a connection output.   two connection outputs of two adjacent electrically conductive elements are connected to a single connection point. For example, the connection point is arranged between the two connection outputs in a circumferential direction.   at least the connection outputs which are situated at the ends of the connection are each provided with a paillon ensuring the contact with the connection point.   each connection point is welded on at least one connection output by means of laser welding or electrical welding.   it comprises at least two connection units distributed on the circumference of the winding coil end.       

     According to a second aspect, the invention relates to a rotary electrical machine, in particular for a motor vehicle, comprising:
         a stator comprising a stator body and an electrical winding, the said electrical winding comprising a plurality of phase windings forming a coil end projecting on an axial end face of the stator body, each phase winding comprising an end forming a winding connection point; and   a plurality of electrically conductive elements each comprising at least one end extending radially in order to form connection outputs to which the connection points are connected, the said electrically conductive elements being connected to one another by over-moulding in order to form an electrical connection unit.       

     Advantageously, the machine comprises at least two connection units distributed on the circumference of the winding coil end. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Other advantages and characteristics of the invention will become apparent from reading the description, illustrated by the figures, in which: 
         FIGS. 1 and 2 , already described, represent a view in perspective and a partial view of a stator winding according to the prior art; 
         FIG. 3 , already described, represents a view in perspective of a stator equipped with a connection unit according to the prior art; 
         FIGS. 4A, 4B and 4C  represent respectively a partial view in perspective, a view from above and a partial front view of a rotary electrical machine according to an embodiment of the invention; 
         FIG. 5  represents a partial front view of a rotary electrical machine according to another embodiment of the invention; 
         FIGS. 6A, 6B and 6C  represent partial views in perspective and from the front of a rotary electrical machine according to another embodiment of the invention; 
         FIGS. 7, 8 and 9  represent partial views in perspective of a rotary electrical machine according to yet another embodiment of the invention, 
     
    
    
     DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT 
     Embodiments of a rotary electrical machine in which the connection unit is partly over-moulded in an electrically insulating material is described in detail hereinafter with reference to the appended drawings. These examples illustrate the characteristics and advantages of the invention. It should however be remembered that the invention is not limited to these examples. 
     In the figures, elements which are identical have identical reference numbers. For reasons of legibility of the figures, the scales of size between elements represented are not respected. 
       FIGS. 4 to 9  represent different partial views of a rotary electrical machine according to a plurality of embodiments of the invention. Irrespective of the embodiment concerned, the rotary electrical machine comprises a stator  100  with an axis X comprising a stator body  110  through which one of the phase windings  120  forming the winding of the stator passes. As previously explained, the phase windings  120  form a coil end at each end of the stator body  110 , A connection unit  150  is fitted in the extension of at least one of the coil ends  125 ,  126 . In the different examples represented in  FIGS. 4 to 9 , the connection unit  150  is fitted in the extension of the upper coil end  125 , on the understanding that it could similarly be fitted in the extension of the lower coil end  126 . 
     In the examples in  FIGS. 4 to 9 , only the upper coil end  125  can he seen, with the housing  112  of the stator surrounding the lower coil end  126 . For reasons of limitation of the size, the connection unit  150  is preferably positioned in the axial extension of the coil end, on the understanding that offset positionings can be envisaged for advantages other than that of the size. 
     The connection unit  150 , which is also known as the interconnector, comprises one or a plurality of electrically conductive elements  155 , which for example are made of copper, over-moulded in an electrically insulating material forming an insulating envelope  156 . This interconnector  150  has a material which is electrically insulating and is resistant to the heat of the winding. It can be positioned supported on the coil end  125  of the stator, which makes it possible to limit the size generated by the presence of the interconnector, and to limit the vibrations generated by the electrical machine during rotation. 
     In some embodiments, the interconnector  150  is positioned supported on one or a plurality of inversion pins  130 , which ensures stable positioning of the interconnector, in particular during operations of installation of the interconnector  150 . In fact, during operations of production of the stator, putting into place of the interconnector is facilitated by its positioning on the inversion pins  130 , and the welding of the neutral points on the interconnector is facilitated by the stability of the assembly. The use of tools in order to retain the interconnector in place is no longer necessary. 
     The interconnector  150  comprises a plurality of electrically conductive elements  155 , also known as conductive tracks, which mostly extend in the interior of the insulating envelope  156 , and which, outside the said insulating envelope, form connection outputs for the neutral points  122 . An interconnector  150  with two electrically conductive elements  155  extending in the interior of the insulating envelope  156  is represented partly in  FIG. 6C . This figure shows in greater detail ends of each of the conductive tracks  155  extending radially from the said insulating envelope  156 , in order each to form a connection output  153 ,  157 . Each conductive track end  153 ,  157 , also known as the output connection., is connected to a neutral point  122 . In fact, the phase windings  120  of the stator form a winding neutral point  122  at each of their ends, these neutral points being connected to one another by means of the interconnector  150 . 
     For this purpose, each conductive track end  155  extends radially from the insulating envelope  156 , forming an angle of approximately 90° with the insulating envelope  156 . Each connection output  153 ,  157  thus forms a connection hook, which can be connected, for example by means of laser welding or electrical welding, to a neutral point  122 . This radial extension of the connection hooks makes it possible to avoid any risk of damage to the insulating envelope during operations of welding of the neutral points. 
     As represented in particular in  FIG. 6C , a neutral point  122  can be connected between the ends of two adjacent conductive tracks. As shown in this example, the two ends of conductive tracks, for example the ends  153  and  157 , are the ends of two adjacent conductive tracks  155 , obtained from a single insulating envelope  156 . These two ends  153 ,  157  extend substantially parallel from the insulating envelope  156  in order to form a double connection hook which is designed to sandwich a neutral point  122 . A welding operation, for example electrical or laser, ensures the electrical connection between the neutral point  122  and each of the ends  153 ,  157 . 
     A single interconnector  150 , for example in the form of an arc of a circle, can connect all the neutral points  122  of the winding. A plurality of interconnectors, for example two, each in the form of an arc of a circle, can be distributed on the circumference of the coil end  125 , with each interconnector connecting only some of the neutral points  122  of the winding. A distribution of this type of the interconnectors permits good ventilation within the rotary electrical machine. In the examples in  FIGS. 4 to 9 , two interconnectors  150   a ,  150   b  are positioned diametrically opposite one another on the circumference of the coil end  125 , each connecting three neutral points. 
     Different modes of connection of the neutral points  122  to the interconnector  150   a  or  150   b  are represented in  FIGS. 4 to 9 . Persons skilled in the art will understand that, when a plurality of interconnectors are fitted in the machine, the connection mode of the neutral points  122  can be identical for each of the interconnectors, as represented in  FIGS. 4 to 9 , or, on the contrary, that the connection mode can differ from one interconnector to another. In the examples described hereinafter, it will he considered that the connection modes of the two interconnectors  150   a ,  150   b  are similar. The connection mode of a single interconnector will thus be described. 
     Each neutral point  122  of the stator winding can be connected to one or two ends of conductive tracks  155 . In the example in  FIGS. 4A-4C , the central neutral point  122   b  is connected between two ends of conductive tracks, and the two lateral neutral points  122   a ,  122   c  are each connected to a single end of a conductive track  155 . For example, for the interconnector  150   a , the lateral neutral point  122   a  is connected to an end  153  of a conductive track  155 . Once they are welded to one another, the neutral point  122   a  and the end  153  of the conductive track form a connection point  163 . Similarly, once they are connected, the lateral neutral point  122   c  and the end  154  of the conductive track form the connection point  161 . The central neutral point  122   b  for its part is connected between the end  151  of a conductive track and the end  152  of another conductive track of the same interconnector  150   a . Once they are welded to one another, the neutral point  122   b  and the ends  151 ,  152  of the conductive tracks form a connection point  162 . In these embodiments, the lateral neutral points  122   a ,  122   c  are welded on the exterior of the interconnector, and close the interconnector  150   a.    
     In the example in  FIG. 5 , the central neutral point  122   b  is connected, as in  FIGS. 4A-4C , between two ends  151 ,  152  of conductive tracks, and the two lateral neutral points  122   a ,  122   c  are each connected to a single end, respectively  153  and  154 , of the conductive track  155 , However, in this example, the lateral neutral points  122   a ,  122   c  are welded in the interior of the interconnector. It is therefore the ends  153 ,  154  which closed the interconnector  150   a.    
     In the examples in  FIGS. 6A, 6B, 6C , each neutral point  122   a ,  122   b  and  122   c  is connected between two ends of conductive tracks, respectively  153  and  157 ,  151  and  152 ,  154  and  158 . In other words, each neutral point, whether it is central or lateral, is connected within a double hook. In these examples, in order to ensure the stability of the interconnector  150   a , a stand  170  can he installed below the insulating envelope  156 , such as to be supported on the coil end  125 , As a variant, a stand can be provided at each of the ends of the interconnector  150   a , with each stand having dimensions designed to prevent any pivoting of the interconnector. This stand  170  is a protuberance, made of insulating material, projecting between the conductive track  155  and the coil end  125 , It can he added below the insulating envelope  156 , or it can be formed by moulding in the electrically insulating material. 
     In embodiments not represented in the figures, where the interconnector  150  is not supported on the coil end, a central stand can be formed below the interconnector, for example facing the portion containing the connection point  162 , in order to ensure the retention of the interconnector in the extension of the coil end. 
     In the embodiments in  FIGS. 4A-4C, 5 and 6A-6C , each connection hook or double hook extends radially through the coil end  125 . Reference is then made to a radial hook/double hook. In other words, each connection point  161 ,  162 ,  163  comprises a connection area, at the end of the conductive track, which extends in a direction perpendicular to the direction in which the neutral point  122  emerges from the winding. The welding, which ensures the electrical conduction between the neutral point and the interconnector, is thus provided at the point of intersection of the hook or double hook, and the neutral point, 
     In the embodiments in  FIGS. 7 to 9 , each connection hook or double hook extends axially in the extension of the winding. Reference is then made to an axial hook/double hook. In other words, each connection point  164 .  165 .  166  comprises a connection area, at the end of the conductive track, which extends in a direction parallel to the direction in which the neutral point  122  emerges from the winding. The connection area and the neutral point are welded parallel to one another, which makes it possible to increase the area of electrical conduction between the two parts. 
     In the connection modes with axial hooks/double hooks, each neutral point  122  can be connected to a single end of a conductive track, or between two ends of conductive tracks. In the example in  FIG. 7 , each neutral point  122   a ,  122   b  and  122   c  is connected axially between two ends of conductive tracks, respectively  153  and  157 ,  151  and  152 ,  154  and  158 . In other words, each neutral point, whether it is central or lateral, is connected within a double hook. In this example, a stand  170  is installed laterally, on both sides of the interconnector, below the insulating envelope  126 , in order to ensure the stability of the said interconnector  150   a.    
     In the examples in  FIGS. 8 and 9 , the central neutral point  122   b  is connected between two ends of conductive tracks, and the two lateral neutral points  122   a ,  122   c  are each connected to a single end of a conductive track  155 . For example, the lateral neutral point  122   a  is connected to an end  153  of a conductive track  155  which, after welding, forms the connection point  166 . Symmetrically, the lateral neutral point  122   c  is connected to an end  154  of a conductive track  155  which, after welding, forms the connection point  164 . The central neutral point  122   b , for its part, is connected between the end  151  of a conductive track and the end  152  of another conductive track of the same interconnector  150   a  which, after welding, forms the connection point  165 . 
     In the example in  FIG. 8  in particular, the lateral neutral points  122   a ,  122   c  are welded on the exterior of the interconnector  150   a , such that they close the interconnector. Alternatively, in the example in  FIG. 9 , the lateral neutral points  122   a ,  122   c  are welded in the interior of the connector  150   a ,, such that it is the ends  153 ,  154  which close the interconnector. 
     In the embodiments where the lateral neutral points are connected to a simple connection hook, i.e. to a single conductive track end, the connection hook is previously provided with a tin paillon in order to ensure a high-quality weld between the neutral point and the connection hook. 
     Irrespective of the embodiments, the three neutral points  122   a ,  122   b ,  122   c  of a stator winding, are connected to one another by means of the interconnector  150 . This interconnector  150  could also connect the phase outputs  124  of the stator, such as to bring all the phase inputs and outputs circumferentially towards an electronic control. 
     The foregoing description focuses on a winding which is connected in the form of a star. It will be appreciated that a departure from the context of the invention will not be constituted by replacing the coupling in the form of a star by a coupling in the form of a triangle, with the neutral points then being replaced by connection points making it possible to connect the phase windings to one another in order to form the triangle connections. 
     Although described by means of a certain number of examples, variants and embodiments, the rotary electrical machine according to the invention comprises different variants, modifications and improvements which will become apparent to persons skilled in the art, on the understanding that these variants, modifications and improvements form part of the scope of the invention as defined by the following claims. For example, a departure from the context of the invention will not be constituted by replacing the plurality of electrical conductors welded to one another which form the winding by continuous wires with a round or rectangular cross-section.