FR3060895B1 - ROTATING ELECTRICAL MACHINE WITH IMPROVED COOLING - Google Patents

Abstract

The invention relates mainly to a rotating electrical machine (10) comprising: - a stator (11), - a rotor (12), - an electrical control module (40) of the machine, - a heat sink (44) associated to the electric control module (40), - front and rear bearings (16, 17) delimiting an internal volume (18) in which the stator (11) and the rotor (12) are arranged, - a cooling chamber (112) ) arranged to allow the circulation of a coolant for cooling the heat sink (44), - the chamber (112) having at least one opening (101) to allow the passage of fluid within the internal volume ( 18).

Description

ROTATING ELECTRICAL MACHINE WITH IMPROVED COOLING

The present invention relates to a rotary electric machine with improved cooling. The invention finds a particularly advantageous, but not exclusive, application with reversible high-power electric machines capable of operating in alternator mode and in motor mode coupled with a host element such as a gearbox reducer.

In a manner known per se, rotary electrical machines comprise a stator and a rotor secured to a shaft. The stator is mounted in a casing configured to rotate the shaft on bearings by means of bearings.

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

Furthermore, the stator comprises a body constituted by a stack of thin sheets forming a crown, the inner face of which is provided with notches open towards the inside to receive phase windings. 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. These windings are polyphase windings connected in a star or a triangle, the outputs of which are connected to an electrical control module.

In certain types of traction chains of a motor vehicle ensuring the transmission of mechanical power from the heat engine to the wheels of the vehicle, a high power reversible rotating electric machine is coupled to the vehicle gearbox. The electric machine is then able to operate in an alternator mode in particular to supply energy to the battery and to the vehicle on-board network, and in an engine mode, not only to ensure the starting of the heat engine, but also to participate traction of the vehicle alone or in combination with the engine.

The present invention aims to improve the cooling performance of the rotary electric machine.

To this end, the subject of the invention is a rotary electric machine, in particular for a motor vehicle, comprising:

- a stator,

- a rotor mounted on a shaft,

- an electrical control module for the rotating electrical machine,

- a heat sink associated with the electrical control module,

a front bearing arranged to support a first bearing carrying the shaft of the rotary electric machine to rotate,

- a rear bearing arranged to support a bearing carrying the shaft of the rotary electric machine to rotate,

- the front and rear bearings defining an internal volume in which the stator and the rotor are arranged,

- a cooling chamber arranged to allow the circulation of a cooling liquid for cooling the heat sink, characterized in that

- The cooling chamber has at least one opening to allow the passage of the fluid inside the internal volume delimited by the front and rear bearings of the rotary electric machine.

The invention thus makes it possible to improve the cooling performance by allowing watering of the active parts via the openings made in the cooling chamber.

According to one embodiment, the opening opens into a nozzle mounted in one end of a bore in the shaft, said shaft being provided with holes for watering the stator.

According to one embodiment, the nozzle is mounted with clearance in the end of the bore of the shaft.

According to one embodiment, the nozzle is connected to the heat sink, for example by being made of material with said heat sink.

According to one embodiment, the cooling chamber has a plurality of openings opening out opposite an axial end face of the stator for cooling a stator winding.

According to one embodiment, the plurality of openings extends at least along an arc of a circle.

According to one embodiment, the plurality of openings is formed in a wall of the heat sink.

According to one embodiment, the cooling chamber is produced inside the heat sink.

According to one embodiment, the cooling chamber is delimited:

- by an axial end face of the rear bearing,

- an axial end face of the heat sink, and

- a seal fitted tightly between the rear bearing and the heat sink.

According to one embodiment, clearances are provided in the rear bearing for the passage of the liquid coming from the nozzle and / or from the openings towards the internal volume of the rotary electric machine.

The shaft may have a grooved end. This makes it possible to adapt the mechanical connection interface of the electrical machine with an external element (pinion or belt) by adapting the type of sleeve which has grooves formed at the internal periphery for cooperation with the grooved end of the shaft. Indeed, this sleeve may have at the outer periphery of the teeth to mesh with a pinion or a pulley for cooperation with a corresponding belt. The choice of the configuration of the sleeve depends on the application and in particular on the configuration of the host element.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These figures are given only by way of illustration but in no way limit the invention.

Figure 1 is a perspective view of a rotary electrical machine according to the present invention;

Figure 2 is a longitudinal sectional view of the rotary electrical machine according to the invention;

Figure 3 is a longitudinal sectional view of the front part of the rotary electric machine according to the invention coupled with a speed reducer;

Figure 4 is a perspective view showing the stator and the interconnector of the rotary electric machine according to the invention;

Figure 5 is a perspective view of the rear part of the rotary electric machine according to the present invention;

FIG. 6a is a perspective view of the heat sink comprising a nozzle for injecting coolant inside the shaft of the rotary electric machine;

Figure 6b is a perspective view of the heat sink of Figure 6a in which the cooling chamber is seen by transparency;

Figure 6c is a side view of the heat sink of Figure 6a;

Figure 7a is a perspective view of the heat sink having a plurality of coolant spray holes in the internal volume of the rotary electric machine according to the invention;

Figure 7b is a perspective view of the heat sink of Figure 7a in which the cooling chamber is seen by transparency;

Figure 7c is a side view of the heat sink of Figure 7a;

Figure 8 is a partial sectional perspective view of the electric machine according to the invention according to the invention provided with a plurality of coolant spray holes in the internal volume of the machine;

Figure 9 is a perspective view of the heat sink illustrating the embodiment in which the corresponding cooling chamber is formed by a seal;

FIG. 10 is a perspective view of the rear bearing of the rotary electrical machine associated with the heat sink of FIG. 9.

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

In the following description, we consider an orientation from front to back, an orientation going from left to right in FIG. 2. Thus, by a front element is meant an element located on the side of the grooved end 73 of the machine shaft and, by rear element, an element situated on the opposite side, that is to say on the side of the electrical control module 40.

Figures 1 and 2 show a rotary electric machine 10 comprising a polyphase stator 11 surrounding a rotor 12 mounted on a shaft 13 of axis X corresponding to the axis of the electric machine. The stator 11 surrounds the rotor 12 with the presence of an air gap between the internal periphery of the stator 11 and the external periphery of the rotor 12. The stator 11 is mounted in a casing 15 provided with a front bearing 16 and a rear bearing 17. Thus, the front and rear bearings 16, 17 define an internal volume 18 in which are arranged the stator 11 and the rotor 12 corresponding to the active parts of the electric machine.

This electric machine 10 is intended to be coupled to a gearbox reducer 20 visible in FIG. 2. The machine is capable of operating in an alternator mode in particular to supply energy to the battery and to the vehicle on-board network. , and in an engine mode, not only to ensure the starting of the thermal engine of the vehicle, but also to participate in the traction of the vehicle alone or in combination with the thermal engine. The power of the machine could for example be between 15kW and 50kW.

More specifically, the rotor 12 comprises a body 22 in the form of a pack of sheets. Permanent magnets 23 are implanted in cavities of the body 22. The magnets 23 may be made of rare earth or ferrite depending on the applications and the desired power of the machine. In addition, the rotor 12 has two flanges 26 each pressed against an axial end face of the rotor 12. These flanges 26 provide axial retention of the magnets 23 and also serve to balance the rotor 12.

Furthermore, the stator 11 comprises a body 27 constituted by a pack of sheets as well as a coil 28. The body 27 is formed by a stack of sheets of sheets held in the form of a pack by means of a suitable fixing system.

The stator body 27 shown in FIG. 4 is provided with teeth 30 extending from an internal periphery of an annular yoke 31 and defining two by two of the notches 32 for mounting the winding 28 of the stator 11. Thus, two notches Successive 32 are separated by a tooth 30. The notches 32 open axially in the axial end faces and radially inward of the stator body 27.

The winding 28 comprises a set of phase windings 33 passing through the notches 32 and forming buns 36 projecting on either side of the stator body 27. The phase windings 33 are obtained here from conductive elements in the form of pins connected together for example by welding. These windings 33 are, for example, three-phase double windings connected in a star.

To this end, one end of the phase windings 33 is connected to the neutral point by means of neutral bars 38 ensuring a connection between the neutral points of the various phase windings 33. The other ends 37 of these windings 33, called phase outputs , are intended to be connected to an electrical control module 40 via an interconnector 41.

As can be seen in Figures 2 and 5, the electrical control module 40 includes a heat sink 44 on which are fixed in particular power modules 45, for example by screwing. These power modules 45 integrate in a manner known per se switches, taking for example the form of MOS type transistors, making it possible to control the rotary electric machine 10 in motor mode or in alternator mode. The electrical control module 40 is mounted flat, via the heat sink 44, against the rear face of the transverse wall 46 of the rear bearing 17.

To this end, as shown in FIG. 4, the interconnector 41, here of generally annular shape, comprises terminals 48 intended to be connected to the phase outputs 37 and connection terminals 49 intended to be electrically connected to lugs 50 power modules 45. The interconnector 41 thus makes it possible to establish a correspondence between the phase outputs 37 and the lugs 50 of the power modules 45 which are angularly offset with respect to the phase outputs 37.

To this end, the terminals 48 are electrically connected to the connection terminals 49 via traces 52 (cf. FIG. 2) on which is molded a body 53 made of an insulating material, such as plastic. The overmolded parts 54 from which the connection terminals 49 originate extend in axial projection relative to the annular portion of the interconnector 41.

The interconnector 41 is fixed to the front face of the transverse wall 46 of the rear bearing 17 directed towards the interior of the machine 10. The interconnector 41 can be fixed by means of fixing members 56, for example screws, intended to cooperate with inserts 57 implanted in the body of the interconnector 41. The interconnector 41 is thus positioned at a distance from the stator body 11, which greatly limits its heating.

Furthermore, in order to allow the positioning of the terminals 49 of the interconnector 41 in front of the lugs 50 of the power modules 45, the rear bearing 17 has openings 61 formed in its transverse wall 46 for the passage of the connection terminals 49. These openings 61 are positioned opposite corresponding openings 63 formed in the heat sink 44 of the electrical control module 40, as shown in FIG. 2.

As can be seen in Figure 3, the electric machine 10 is configured, so that a grooved end 73 of the shaft 13 engages with a grooved inner periphery 74 of corresponding shape of a sleeve 75. This allows thus linking the shaft 13 in rotation with the sleeve 75. The sleeve 75 may also include a helical toothing 76 formed in its external periphery intended to cooperate with the teeth of a corresponding pinion of the reduction gear 20.

To ensure rotational mounting of the shaft 13 relative to the front bearing 16, a bearing 77 is interposed between the shaft 13 and the front bearing 16. The bearing 77 may for example be a ball or needle bearing .

The outer periphery of the bearing 77 cooperates with the inner periphery of a nose 85 of the machine constituted by an annular wall forming an axial projection relative to the transverse wall 88 of the front bearing 16. Furthermore, as illustrated by the figure 2, the rear bearing 103 is mounted in a corresponding housing 104 in the rear bearing 17.

Advantageously, the electric machine 10 is cooled by means of a cooling circuit 109 allowing the flow of a cooling liquid, in this case a water-based liquid, inside the machine. Alternatively, the coolant is oil-based.

This circuit 109 has an inlet 111 formed in the heat sink 44 and opening into a cooling chamber 112 for the circulation of a cooling liquid for cooling the heat sink 44, in order to evacuate the calories dissipated by the electrical module of command 40.

The chamber 112 can be produced inside the heat sink 44, that is to say that the chamber 112 can be produced during the molding or the machining of the heat sink 44 to define a hollow volume inside of the heat sink 44. The chamber 112 is thus delimited by internal faces of the heat sink 44.

In order to improve the cooling of the active parts 11, 12 of the electric machine, the cooling chamber 112 has at least one opening to allow the passage of the fluid inside the internal volume 18 delimited by the front bearings 16 and rear 17 of the machine.

In the embodiment of FIGS. 2, 6a, 6b, 6c, an opening 101 opens into a nozzle 102 mounted with a clearance in one end of a central bore 107 of the shaft 13. The shaft 13 is provided with holes 108 for watering the stator 11. These holes 108 for example of radial orientation have for this purpose an end opening into the central bore 107 and another end opening inside the internal volume 18, preferably opposite the updos 36.

The nozzle 102 is connected to the heat sink 44, for example by taking the form of an annular wall made from material with said heat sink 44. As a variant, the nozzle 102 is attached to the mounting on the heat sink 44. The attached nozzle 102 may thus for example be welded, glued, or force-fitted onto the heat sink 44.

In the embodiment of FIGS. 7a, 7b, and 8, the cooling chamber 112 has a plurality of openings 110 opening out opposite an axial end face of the stator 11 for cooling the winding 28 of the stator 11. These openings 110 are in this case formed in a wall of the heat sink 44 facing the rear bearing 17.

Preferably, the plurality of openings 110 extends in an arc of a circle or a complete circle. These openings 110 may thus extend over an angular range of the order of 360 degrees or over an angular range less than 300 degrees, in particular over 180 degrees or 120 degrees.

In addition, clearances are provided in the rear bearing 17 and positioned opposite the openings 110 of the cooling chamber 112. This allows the passage of the liquid from the nozzle 102 and / or the openings 110 to the internal volume 18 of the rotating electric machine. In the embodiment of Figure 2, the rear bearing 17 thus has a through clearance 113 to allow passage of the nozzle 102 inside the shaft 13. In the embodiment of Figure 8, the bearing rear 17 has a clearance 116 positioned opposite the openings 110 made in the chamber 112.

The fixing of the heat sink 44 on the rear bearing 17 can be carried out by means of fixing members 118, such as screws, passing through perforated ears 119 protruding radially from the heat sink 44 and intended to cooperate with tapped holes 122 corresponding spares at the outer periphery of the rear bearing 17, as shown in FIG. 2.

Of course, the embodiments of FIGS. 2, 6a to 6c and of FIGS. 7a, 7b and 8 may be combined with each other, that is to say that the heat sink 44 may have an opening opening into the nozzle 102 in communication with the internal bore of the shaft 13 as well as a plurality of openings 110 opening directly into the internal volume 18.

Alternatively, as illustrated in FIGS. 9 and 10, the cooling chamber 112 may be delimited by an axial end face of the rear bearing 17, an axial end face opposite the heat sink 44, and a seal 124 mounted tight between the rear bearing 17 and the heat sink 44.

To this end, the seal 124 which has a closed contour defining that of the chamber 112 may be of the O-ring type. As can be seen in Figure 9, a groove 126 receiving the seal 124 is formed in the heat sink 44. The seal 124 defines a closed volume in the form of an elongated C and the ends of which are very close, so that the chamber 112 extends circumferentially over more than 300 degrees and almost 360 degrees to cool the entire volume of the heat sink 44. The heat sink 44 can be hollowed out in the surface delimited by the seal 124 to increase the volume of the chamber 112. In this case, the openings 101 and / or 110 are formed in the transverse wall 46 of the rear bearing 17.

Preferably, whatever its embodiment, the cooling chamber 112 is arranged to allow the cooling of capacitors and / or power modules 45 of the electrical control module 40. To this end, the cooling chamber 112 switches on. below these items. In other words, there is an at least partial superposition in axial projection along the axis X between the projected surface of these components of the module 40 and the projected surface of the cooling chamber 112. The inlet of the cooling chamber 112 may be positioned near a chimney 127 coming from the heat sink 44 in which the capacitors are mounted, as shown in FIG. 6c.

The liquid from the chamber 112 can also flow to a chamber 114 delimited by the front 16 and rear bearings 17. For this purpose, the coolant passes through a channel 115 opening on the one hand into the chamber 114 defined by the front 16 and rear 17 bearings and on the other hand in the chamber 112 of the dissipator 44.

More specifically, the cooling chamber 114 is delimited by the external periphery of the side wall 125 of the front bearing 16 and the internal periphery of the side wall 117 of the rear bearing 17. This cooling chamber 114 is closed at its axial ends by two 128 O-ring seals. The stator 11 is preferably mounted hooped inside the front bearing 16 so as to establish intimate contact between the external periphery of the stator body 27 and the internal periphery of the side wall 125 of the front bearing 16.

The channel 115 is produced in the side wall 117 of the rear bearing 17, that is to say that the walls delimiting the channel 115 are in one piece with the side wall 117 of the rear bearing 17. The channel 115 may for example be obtained by molding or by machining the side wall 117 of the rear bearing 17.

A seal 120 visible in Figure 2 is disposed between the rear bearing 17 and the heat sink 44 around the channel 115. This ensures a seal of the electric machine 10 vis-à-vis the coolant.

After having circulated in the chamber 114 which extends around the stator 11 to ensure its cooling over approximately 360 degrees, the liquid is evacuated via a liquid outlet 121 visible in FIG. 1.

Furthermore, a seal 131 visible in FIGS. 1 and 2 is carried by an external periphery of the nose 85 to prevent particles or liquid from entering the machine via the bearing 77. This seal 131 is radially disposed between the external periphery of the nose 85 and the internal periphery of the corresponding housing 123 formed in the casing 98 of the reduction gear 20.

A seal 135, for example of the triple lip type, may also be positioned radially between an external periphery of the sleeve 75 and a face of the casing 98 delimiting an opening for the passage of the sleeve 75, as shown in FIG. 3. The seal 135 is positioned axially between the bearing 136 ensuring the guiding in rotation of the sleeve 75 relative to the casing 98 of the reduction gear 20 and the front bearing 77 of the rotating electrical machine 10.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention from which one would not depart by replacing the various elements with any other equivalent.

Furthermore, the various features, variations, and / or embodiments of the present invention can be combined with one another in various combinations, insofar as they are not incompatible or mutually exclusive of each other.

Claims (10)

1. Rotating electric machine (10), in particular for a motor vehicle, comprising: - a stator (11), - a rotor (12) mounted on a shaft (13), - an electrical control module (40) of the rotating electrical machine, - a heat sink (44) associated with the electrical control module (40), a front bearing (16) arranged to support a first bearing (77) carrying the shaft (13) of the rotary electric machine (10) in rotation, a rear bearing (17) arranged to support a bearing (103) carrying the shaft (13) of the rotary electric machine (10) in rotation, - the front and rear bearings (16, 17) defining an internal volume (18) in which the stator (11) and the rotor (12) are arranged, - a cooling chamber (112) arranged to allow the circulation of a cooling liquid for cooling the heat sink (44), characterized in that - the cooling chamber (112) has at least one opening (101, 110) to allow the passage of the fluid inside the internal volume (18) delimited by the front and rear bearings (16, 17) of the electric machine rotating. 2. Rotating electric machine according to claim 1, characterized in that the opening (101) opens into a nozzle (102) mounted in one end of a bore (107) of the shaft (13), said shaft (13 ) being provided with holes (108) for watering the stator (11). 3. Rotating electric machine according to claim 2, characterized in that the nozzle (102) is mounted with clearance in the end of the bore (107) of the shaft (13). 4. Rotating electric machine according to claim 2 or 3, characterized in that the nozzle (102) is connected to the heat sink (44), for example by being made of material with said heat sink (44). 5. rotary electric machine according to any one of claims 1 to 4, characterized in that the cooling chamber (112) has a plurality of openings (110) opening opposite an end face axial of the stator (11) for cooling a winding (28) of the stator (11). 6. rotary electric machine according to claim 5, characterized in that the plurality of openings (110) extends at least in an arc. 7. Rotating electric machine according to claim 5 or 6, characterized in that the plurality of openings (110) is formed in a wall of the heat sink (44). 8. Rotating electric machine according to any one of claims 1 to 7, characterized in that the cooling chamber (112) is produced inside the heat sink (44). 9. Rotating electric machine according to any one of claims 1 to 8, characterized in that the cooling chamber (112) is delimited: - by an axial end face of the rear bearing (17), - an axial end face of the heat sink (44), and - A seal (124) mounted tightly between the rear bearing (17) and the heat sink (44). 10. Rotating electric machine according to claim 2 or 5, characterized in that clearances (113, 116) are provided in the rear bearing (17) for the passage of the liquid coming from the nozzle (102) and / or the openings ( 110) to the internal volume (18) of the rotary electric machine.