EP3455926A1 - Rotary electrical machine with optimised cooling - Google Patents

Abstract

The invention relates mainly to a rotary electrical machine including: a bearing (12); a stator (11) including a stator body (13); and a tubular ring (27), said stator body (13) being mounted braced in the ring (27); a cooling chamber (28) for circulating coolant liquid defined by an outer periphery of said tubular ring (27) and an inner periphery of said bearing (12); said bearing (12) including an intake and an outlet of coolant liquid, said machine including a separating wall (42) for separating said cooling chamber (28) extending between said intake and said outlet of coolant liquid, said separating wall (42) being added relative to said tubular ring (27) and including at the ends thereof attachment members for holding said wall (42) on said tubular ring (27).

Description

 ROTATING ELECTRIC MACHINE WITH OPTIMIZED COOLING

The invention relates to a rotating electric machine with optimized cooling. The invention relates to the field of electrical machines such as motors, alternators, or alternator-starters. Electric machines are known comprising rotor integral with a driving shaft and / or driven and a stator which surrounds the rotor with the presence of an air gap. The stator is carried by a casing which comprises bearings for the rotational mounting of the rotor shaft.

The rotor may comprise a body formed by a stack of sheets of sheets held in pack form by means of a suitable fastening system. The rotor comprises poles formed for example by permanent magnets housed in cavities formed in the magnetic mass of the rotor. Alternatively, in a so-called "salient" poles architecture, the poles are formed by coils wound around rotor arms. Alternatively, the rotor has claw poles.

Furthermore, the stator comprises a body consisting of a stack of thin sheets forming a ring, whose inner face is provided with notches open inwardly to receive phase windings. These windings pass through the notches of the stator body and form buns protruding from both sides of the stator body. The phase windings are obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins connected together by welding. Alternatively, in the case of a concentric type winding, the polyphase electrical machine comprises a stator winding formed by a plurality of preformed coils mounted around the stator teeth via a coil insulator.

The heat generated by the flow of current through the stator winding can be discharged to a cooling circuit. This cooling circuit comprises a chamber in which circulates a coolant liquid. The cooling chamber is delimited by an inner periphery of the casing and an outer periphery of a tubular ring in which is mounted shrouded the stator body. The outer periphery of the stator body is thus in contact with the inner periphery of the tubular ring to facilitate the evacuation of heat to the cooling chamber. However, the realization of the cooling chamber can cause a deformation of the ring in the shrinking area with the stator body, which is likely to cause problems of mechanical strength, efficiency and sealing.

The present invention aims to effectively remedy this disadvantage by proposing a rotating electrical machine comprising:

- a step,

 a stator comprising a stator body,

 a tubular ring, said stator body being mounted shrunk in said tubular ring,

 a cooling chamber for circulating coolant defined by an outer periphery of said tubular ring and an inner periphery of said bearing,

 said bearing having an inlet and a coolant outlet,

characterized in that said rotating electrical machine has a partition wall for separating said cooling chamber extending between said inlet and said coolant outlet, so that the coolant flows from said inlet to said liquid outlet of cooling, said partition wall being attached relative to said tubular ring and having at its ends fasteners for maintaining said partition wall on said tubular ring.

The invention thus makes it possible to prevent the ring from being deformed in the zone shrunk by the partition wall when it is fastened. The invention thus ensures a good contact surface between the outer periphery of the stator body and the inner periphery of the ring during hooping.

According to one embodiment, the stator comprises a pack of sheets.

In one embodiment, said partition wall extends rectilinearly. In one embodiment, said partition wall is inclined with respect to an axis of said tubular ring.

This inclination of the wall facilitates the diffusion or the recovery of the liquid in the chamber. In one embodiment, the coolant inlet and outlet are positioned at a single axial end of the partition wall to facilitate diffusion or recovery of the liquid into the chamber.

According to one embodiment, the coolant inlet is positioned at one of the axial ends of the partition wall and the coolant outlet is positioned at the other of the axial ends of the partition wall for facilitate the diffusion or the recovery of the liquid in the chamber.

In one embodiment, said partition wall has a curved shape. In one embodiment, the rotating electrical machine has a single partition wall for separating said cooling chamber extending between said inlet and said coolant outlet.

In one embodiment, the wall extends axially from one axial side of the tubular ring to the other axial side of the tubular ring. In one embodiment, said partition wall has a central recess arranged to form a space between said inlet and said coolant outlet, so as to be isolated from the coolant when the coolant flows into said cooling chamber. In one embodiment, said partition wall has a spiral shape wrapped around said tubular ring.

According to one embodiment, said partition wall has a section of rectangular shape. According to one embodiment, said tubular ring comprises two annular grooves each positioned at an axial end of said tubular ring, each annular groove being formed in a flange with respect to an outer face of said tubular ring, said annular grooves being arranged to receive a seal of sealing for sealing said cooling chamber.

According to one embodiment, said fasteners comprise fastening tabs welded to a rim of an annular groove.

According to one embodiment, at each end of said partition wall, said attachment tabs extend on either side of said partition wall.

According to one embodiment, said partition wall and said fasteners are made of metal.

According to one embodiment, said fasteners form an elastically deformable and open collar for snapping onto an outer periphery of said tubular ring.

According to one embodiment, said rotating electrical machine comprises a retaining device in rotation of said partition wall.

According to one embodiment, said partition wall is made of plastic.

According to one embodiment, said rotational retention device comprises bosses formed on the side of an outer face of said tubular ring.

According to one embodiment, said bosses are positioned on each side of said partition wall. According to one embodiment, said bosses are positioned in said central recess of said partition wall.

According to one embodiment, said partition wall is made of metal. According to one embodiment, said rotational retention device comprises welds made between a fixing member and a corresponding flange of said groove.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given for illustrative but not limiting of the invention.

FIG. 1 shows a perspective view of the stator and the bearing of a rotating electrical machine according to the invention;

Figure 2 is a perspective view of a rotating electrical machine according to the invention showing a transparent partition wall of the cooling chamber;

Figure 3 is a partial schematic sectional view of a rotary electric machine according to the invention illustrating the configuration of the cooling chamber; Figure 4 is a perspective view of the tubular ring and a partition wall of the cooling chamber having a curved shape;

Figures 5a to 5d are perspective views illustrating alternative embodiments of the partition wall of the cooling chamber;

Figures 6a and 6b are perspective views illustrating retaining devices in rotation of a partition wall of the cooling chamber according to the invention.

Identical, similar or similar elements retain the same reference from one figure to another.

FIG. 1 shows a rotating electrical machine 10 comprising a stator 1 1 carried by a bearing 12. The stator 1 1 comprises a body 13 constituted by a stack of thin sheets forming a ring, the inner face of which is provided with teeth 16 delimiting two at two of the notches open towards the inside of the stator body 1 1. In the example shown, the winding 19 of the stator January 1 is concentric type formed by a plurality of preformed coils 20 each mounted around a tooth 16 of the stator January 1 by means of a coil insulator. Alternatively, the winding 19 may be made from windings passing through the notches of the stator body 13 and forming protruding buns on either side of the body 13. The phase windings can be obtained for example from a continuous wire covered with enamel or from conductive elements in the form of pins connected together by welding. More specifically, as illustrated by FIG. 2, the bearing 12 comprises a central wall 23 having an axially oriented annular shape and two transverse end walls 24 having a substantially radial orientation with respect to the X axis of the machine. Each of the end walls 24 is provided at its center with a bearing for rotatably mounting one end of the rotor shaft (not shown).

The bearing 12 may be made in two parts with a first cup-shaped portion having the central wall 23 and one of the end walls 24. This first portion is assembled with a second portion formed of the other end wall 24 As a variant, the central wall 23 and the end walls 24 constitute distinct parts which are assembled together, for example by means of tie rods. The bearing 12 may for example be made of a moldable material good thermal conductor, such as aluminum.

As can be seen clearly in FIG. 3, the stator body 13 is mounted in a ring 27 of tubular form. A cooling chamber 28 for the circulation of coolant is delimited by an outer periphery of the tubular ring 27 and an inner periphery of the central wall 23 of the bearing 12. The outer periphery of the stator body 13 is thus in contact with the inner periphery of the central wall 23 of the ring 27, in order to facilitate the evacuation of the heat towards the cooling chamber 28.

The ring 27 comprises two annular grooves 31 each positioned at an axial end of the ring 27. More precisely, each groove 31 is formed in a flange 34 relative to the outer face of the ring 27. Each groove 31 is arranged to receive a seal 35 to seal the chamber 28.

One of the grooves 31 may have a smaller diameter than the other groove 31 so as to facilitate the insertion of the tubular ring 27 in the bearing 12.

The bearing 12 further comprises an inlet 38 and a coolant outlet 39 visible in FIG. 2. A separation wall 42 separates the cooling chamber 28 extending between the inlet 38 and the outlet 39 of liquid cooling, so that the coolant flows, along the arrows F1, from the inlet 38 to the outlet 39 of coolant to evacuate the heat generated by the coil 19 of the stator January 1.

The partition wall 42 is attached to the ring 27 and has at its ends fasteners 43 for holding the partition wall 42 on the ring 27.

In the embodiment of Figure 2, the partition wall 42 extends rectilinearly between the two end flanges 34 of the ring 27. The partition wall 42 may extend parallel to the axis Y of the ring 27 which coincides with the axis X when the ring 27 is mounted inside the rotating electrical machine 10.

Alternatively, as shown in Figure 4, the partition wall 42 may have a curved shape, for example in the form of elongated S. The wall 42 thus has two substantially rectilinear end portions 46 interconnected by a curved portion 47 having a point of inflection in which the curvature of the wall 42 changes direction.

In addition, the partition wall 42 comprises fixing lugs 50 forming the fasteners 43. These lugs 50 are welded at their free end to a flange 34 of a groove 31 along the welded zones referenced 51. At each end of the partition wall 42, the tabs 50 extend on either side of the partition wall 42. tabs 50 further extend along a portion of the circumferential periphery of the ring 27. The partition wall 42 and the fastening tabs 50 are preferably made of metal.

Advantageously, the partition wall 42 may have a section of rectangular shape with a larger side of the rectangle bearing against the outer periphery of the ring 27. This maximizes the contact area between the partition wall 42 and the periphery outer ring 27 to improve the seal of the assembly.

In the embodiments of FIGS. 5a to 5d, the fasteners 43 each form a collar 54 that is open and elastically deformable in order to be snap-fastened on the outer periphery of the ring 27. For this purpose, the collar 54 has, to the unconstrained state, an inner diameter slightly smaller than the outer diameter of the ring 27. In these embodiments, the partition wall 42 incorporating the open collars 54 at each of its axial ends may be made of a material based on metal or plastic to give it some elasticity.

The partition wall 42 may be inclined relative to the Y axis of the ring 27, as shown in Figure 5a. Preferably, the inlet 38 and the coolant outlet 39 are positioned at the corners formed by the central portion of the wall 42 with the collar 54 to facilitate diffusion or recovery of the liquid in the chamber.

In the embodiment of Figure 5b, the partition wall 42 has a central recess 57 arranged to form a space between the inlet 38 and the outlet 39, so as to be isolated from the coolant when it circulates in the the cooling chamber 28.

In one embodiment of FIG. 5b, the inlet 38 and the outlet 39 are each disposed at an axial end of the ring 27.

In a variant, the inlet 38 and the outlet 39 may be arranged at the same axial end of the ring 27. In the embodiment of FIG. 5c, the partition wall 42 has the curved shape of FIG. 4 and is provided with inclined ends 46 relative to the Y axis of the ring 27. The fasteners 43 located at the ends of the wall 42 are formed by open collars 54.

In the embodiment of Figure 5d, the partition wall 42 has a spiral shape wound around the ring 27. The cooling liquid performs in this configuration a complete revolution of the ring 27 before being evacuated via the exit 39.

Advantageously, the partition wall 42 can be arranged to allow the coolant to perform a predetermined number of complete turns in the ring 27 before being discharged via the outlet 39. In order to maintain the wall 42 in position on the tubular ring 27, it is possible to provide a rotation retaining device 60 of the partition wall 42, as shown in Figures 6a and 6b. In the case where the partition wall 42 is made of plastic material, the rotation retaining device 60 has bosses 61 formed on the side of an outer face of the ring 27. As shown in FIG. bosses 61 are positioned in the recess 57 of the partition wall 42. Alternatively, the bosses 61 may be positioned on each side of a partition wall 42 without recess.

In the case where the partition wall 42 is made of metal, the rotational retention device 60 comprises welds 62 made between a fixing member 43 and the rim 34 of the groove 31. This is illustrated in Figure 6b.

It should be noted that the rotor of the machine, not shown in the figures, may comprise a body formed by a stack of sheet metal sheets held in pack form by means of a suitable fastening system. The rotor comprises poles formed for example by permanent magnets housed in cavities formed in the magnetic mass of the rotor. Alternatively, in a so-called "salient" poles architecture, the poles are formed by coils wound around rotor arms. Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention which would not be overcome by replacing the different elements by any other equivalent.

In addition, the various features, variations and / or embodiments of the present invention may be associated with each other in various combinations, to the extent that they are not incompatible or exclusive of each other.

Claims

1. Rotating electrical machine (10) comprising:  a bearing (12),  a stator (1 1) comprising a stator body (13),  a tubular ring (27), said stator body (13) being mounted shrunk in said tubular ring (27),  a cooling chamber (28) for the circulation of cooling liquid defined by an outer periphery of said tubular ring (27) and an internal periphery of said bearing (12),  said bearing (12) having an inlet (38) and an outlet (39) for coolant,  characterized in that said rotating electrical machine (10) has a partition wall (42) for separating said cooling chamber (28) extending between said inlet (38) and said coolant outlet (39) so that that the coolant flows from said inlet (38) to said coolant outlet (39), said partition wall (42) being attached with respect to said tubular ring (27) and having at its ends fasteners ( 43) for maintaining said partition wall (42) on said tubular ring (27). 2. rotary electric machine according to claim 1, characterized in that said partition wall (42) extends rectilinearly. 3. rotary electric machine according to claim 2, characterized in that said partition wall (42) is inclined relative to an axis (Y) of said tubular ring (27). 4. rotary electric machine according to claim 1, characterized in that said partition wall (42) has a curved shape. The rotary electric machine according to claim 1, characterized in that said partition wall (42) has a central recess (57) arranged to form a space between said inlet (38) and said coolant outlet (39), so as to be isolated from the coolant when the coolant circulates in said chamber of cooling (28). 6. Rotating electrical machine according to claim 1, characterized in that said partition wall (42) has a spiral shape wound around said tubular ring (27). 7. rotary electric machine according to any one of claims 1 to 6, characterized in that said partition wall (42) has a rectangular section. 8. rotary electrical machine according to any one of claims 1 to 7, characterized in that said tubular ring (27) comprises two annular grooves (31) each positioned at an axial end of said tubular ring (27), each annular groove ( 31) being formed in a rim (34) with respect to an outer face of said tubular ring (27), said annular grooves (31) being arranged to receive a seal (35) to seal said chamber cooling (28). 9. rotary electrical machine according to claim 8, characterized in that said fasteners (43) comprise fastening lugs (50) welded to a flange (34) of an annular groove (31). 10. Rotating electrical machine according to claim 9, characterized in that at each end of said partition wall (42), said fixing lugs (50) extend on either side of said partition wall (42). 1 1. Rotary electric machine according to claim 9 or 10, characterized in that said partition wall (42) and said fasteners (43) are made of metal. 12. A rotary electric machine according to any one of claims 1 to 7, characterized in that said fasteners (43) form a collar (54) open and elastically deformable to snap on an outer periphery of said tubular ring ( 27). Rotating electric machine according to the claim characterized in that it comprises a device for retaining rotation (60) of said partition wall (42). 14. A rotary electric machine according to claim 12 or 13, characterized in that said partition wall (42) is made of plastics material. 15. The rotary electrical machine according to claims 13 and 14, characterized in that said rotational retainer (60) comprises bosses (61) formed on the side of an outer face of said tubular ring (27).