WO2017134375A1

WO2017134375A1 - Rotating electrical machine provided with at least one ventilation opening in a heat sink

Info

Publication number: WO2017134375A1
Application number: PCT/FR2017/050206
Authority: WO
Inventors: Michel Fakes; Philippe Masson
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2016-02-02
Filing date: 2017-01-30
Publication date: 2017-08-10
Also published as: DE112017000608T5; JP2019503645A; JP7008034B2; FR3047361B1; FR3047361A1

Abstract

The invention relates mainly to a rotating electrical machine (100) capable of operating at least in alternator mode in order to supply power to a motor vehicle, said rotating electrical machine including: a heat sink (16) including a first surface, on which said electronic power circuit (15) is mounted, as well as a second surface, opposite said first surface and oriented towards said rear bearing (4); a protective cover (11) comprising at least one axial opening (11b), characterised in that said heat sink (16) comprises at least one main opening (16a), allowing the passage of said rotation shaft (2), and at least one ventilation opening, allowing the coolant to pass through said axial opening (11b) of said cover (11).

Description

ROTATING ELECTRIC MACHINE HAVING AT LEAST ONE AERATION OPENING IN A HEAT SINK

The invention relates to a rotating electrical machine provided with at least one ventilation opening in a heat sink. The invention finds a particularly advantageous, but not exclusive, application with rotating electrical machines operating at least in alternator mode.

In known manner, the rotating electrical machines comprise a stator and a rotor secured to a shaft. The rotor may be integral with a driving shaft and / or driven. The stator is mounted in a housing configured to rotate the shaft on bearings by bearings. The rotor comprises a body formed by a stack of sheets of sheet metal 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.

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. These windings are polyphase windings connected in star or delta whose outputs are connected to an electronic power circuit comprising in particular a rectifier bridge in the case of an alternator. Such a bridge rectifier can dissipate an energy of the order of 150 Watts. As described in document FR2847085, in order to cool the rectifier bridge, a dissipator has a face on which the circuit is mounted. power electronics, and an opposite face facing the rear bearing. A cooling fluid flow passage, in this case air set in motion by a fan carried by the rotor, is located between the face of the rear bearing facing the dissipator and the opposite side of the dissipator.

The air is withdrawn laterally and then discharged after circulation in the passage via an air outlet located on the same side as the air inlet. However, because of the proximity of the inlet and the side air outlet, some of the heated air can be reintroduced into the electric machine. The invention aims to effectively remedy this disadvantage by proposing a rotating electrical machine capable of operating at least in alternator mode to provide power to a motor vehicle, said rotating electrical machine comprising:

- a rear bearing,

a rotor fixed on a rotation shaft supported by at least the rear bearing,

a stator surrounding said rotor, said stator comprising an armature winding comprising windings constituting phases of the electric machine,

said rear bearing having lateral openings for outputting a cooling fluid, and at least one axial opening for entering the cooling fluid into said stator;

an electronic power circuit electrically connected to the phase windings of said stator,

a heat sink comprising on the one hand a first face on which said electronic power circuit is mounted, and on the other hand, a second face, opposite to said first face and oriented towards said rear bearing,

a protective cover comprising at least one axial opening, characterized in that said heat sink comprises at least one main opening for the passage of said rotation shaft and at least one ventilation opening allowing the cooling fluid to pass from said axial opening of said cover towards said axial opening of said rear bearing. The invention thus makes it possible to introduce fresh fluid into the electric machine via the axial opening of the cover, in order to reduce the temperature of the fluid injected inside the electrical machine to improve cooling. The fact that the fluid passes through an opening of the dissipator makes it possible to extend the exchange surface of the dissipator in the path of the fluid. Thus the heatsink bridge is better cooled.

In one embodiment, said heat sink has a plurality of ventilation apertures. This maximizes the axial surface of the heatsink licked by the axial air flow inside the electric machine.

According to one embodiment, at least one ventilation opening extends over an angular portion around said rotation shaft. This makes it possible to increase the zone of the heat exchange between the openings of the dissipator and the axial channel of the cooling fluid. Thus a larger area of the dissipator is cooled by the axial flow.

According to an example of this embodiment, the openings are staggered. This improves the thermal cooling.

According to one embodiment, said electric machine comprises a position sensor positioned around said rotation shaft closing at least in part said main opening. This saves axial space by incorporating the sensor in the thickness of the heatsink while having a cooling of the heatsink.

In one embodiment, said position sensor is a resolver closing said main opening along an entire periphery of said rotation shaft. This makes it possible to force the fluid to pass through heatsink openings and not between the heatsink and the shaft.

In one embodiment, said position sensor is a Hall effect sensor.

In one embodiment, said heat sink has a radial indentation for integration of said position sensor. According to one embodiment, said rear bearing comprises at least one deflector placed at the outlet of a lateral opening of said rear bearing. This makes it possible to reduce the looping of the hot air, that is to say to avoid re-sucking the hot air exiting through the radial openings of the bearing. According to one embodiment, said protective cover covers said electronic power circuit and the dissipator.

According to one embodiment, said protective cover comprises at least one end raised to form said deflector.

According to one embodiment, said rotating electrical machine comprises a cooling fluid flow passage between an upper face of said rear bearing directed towards said heat sink and the second face of said heat sink, and the second face of said heat sink comprises cooling fins, and at least one axial end of a fin extends axially at least to the level of the upper face of said rear bearing. This allows, without increasing the axial size of the electric machine, to increase the exchange surface by elongation of the fins and thus effectively improve the cooling of the electric machine.

In one embodiment, at least one fin comprises a portion located inside said axial opening of said rear bearing.

In one embodiment, said fin extends solely opposite said axial opening of said rear bearing.

According to one embodiment, the at least one fin further comprises a portion vis-à-vis the solid upper face of said rear bearing. According to one embodiment, said rotating electrical machine further comprises at least a second fin located opposite said axial opening of said rear bearing and at a distance from the upper face of said rear bearing.

According to one embodiment, said machine further comprises a brush holder and in that the brush holder is located radially between the rotor and the heat sink, in particular between a plate of the heat sink and the rotor and axially between the bearing and the position sensor. This saves axial size. In another embodiment, said machine further comprises a brush holder and in that the brush holder is located radially between the rotor and the electronics and axially between the heat sink and the cover.

According to one embodiment, the electronics are in modules overmolded on the electronic components and traces connected to the electronic components, which are overmolded in a housing.

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.

Figure 1a shows a partial sectional view of the rear portion of an alternator-starter according to the present invention;

Figure 1b shows an alternative embodiment of the alternator-starter of Figure 1a;

FIG. 2 represents a side view of the cooling fins used in the starter-alternator of FIG. 1a,

Figures 3a and 3b are side views illustrating alternative embodiments of the cooling fins; Figure 4 shows the rear part of the alternator-starter with the mezzanine on which is placed the power electronics;

Figure 5 is a detailed view of the rear bearing showing the openings opposite which extend at least a portion of the cooling fins; Figure 6 is a partial sectional view of an alternative embodiment of the alternator-starter according to the present invention comprising a heat sink according to the invention provided with ventilation openings;

Figure 7 is a top view of the dissipator of the figure of Figure 6; Figures 8a and 8b are top views illustrating alternative embodiments of the heat sink according to the invention.

Identical, similar or similar elements retain the same reference from one figure to another. Figure 1a shows a sectional view of the rear of an alternator-starter 100 having a cooling device according to the invention. This alternator-starter 100 is able to operate reversibly in a generator mode to provide power to the battery and to the on-board vehicle network, and in a motor mode to provide in particular a mechanical power to the engine of the vehicle in order to ensure its startup.

The alternator / starter 100 comprises a rotor 1 of axis X fixed on a rotation shaft 2. This rotor 1 is surrounded by a stator 3 provided with an induced coil 7. The stator 3 is supported by the rear bearing 4 and the front bearing (not shown), which holds the rotation shaft 2 by means of bearings 6.

The alternator / starter 100 comprises a rectifier bridge with MOS power transistors, associated with control units of these power transistors. This bridge rectifier and these control units together form the power electronics of the alternator-starter, referenced 15. This power electronics 15 is mounted on the upper face of a heat sink 16. The electronic circuit 15 power can be electrically connected to the phase windings of the stator 3 directly or through a connector.

In particular the connector (not shown in the drawings) may include traces for connecting the phases and being overmolded with a plastic material. This connector can be fixed to the bearing 4 between the bearing 4 and the fins 181 of the heat sink 16.

The face axially oriented towards the rear bearing 4 of this heat sink 16 forms a wall of a flow passage 17 of the cooling fluid in the alternator-starter 100. The other wall of this passage 17 is formed by the upper face of the rear bearing 4 facing the heat sink 16.

The protective cover 1 1 has openings 1 1 a located opposite the flow passage of the fluid 17. In this way, the cooling fluid, and in particular the air, is introduced into the rear of the alternator. - Starter 100 laterally by these openings 1 1 a then flows in the passage 17, under the dissipator 16, cooling the power electronics 15. A fan 5, fixed on the rotation shaft 2 or on the rotor 1, ensures suction of the air, or any other fluid, inside the passage 17. The air flows towards axial openings 4a of the bearing 4 before being discharged through the lateral openings 4b of the bearing 4.

The dissipator 16 comprises, on its lower face opposite the face carrying the power electronics, cooling fins 18, 18 ', 18 ", 18"', 18 "". In the embodiment of FIGS. 1a and 2, the fins 18 comprise a first portion 181 extending opposite the solid face of the bearing 4 and a second portion 182 which is longer axially than the first portion 181. In this case, the second portion 182 is located vis-à-vis a corresponding opening 4a of the bearing 4 and extends at least partially inside the opening 4a. The portion 182 of the fin 18 is considered to be "facing" a central opening 4a when a straight line orthogonal to the face of the dissipator 16 passing through the portion 182 also passes through the axial opening 4a. corresponding.

As can be seen in FIG. 2, the dissipator 16 also has fins 18 'situated opposite the solid face of the bearing 4. The fins 18' have an axial end positioned at a distance from the face of the bearing 4 .

In the embodiment of FIG. 3a, the fins 18 "are situated vis-à-vis the opening 4a and at a distance from the upper face of the bearing 4. More precisely, as can be seen more clearly in FIG. each opening 4a has a first lateral edge 41 and a second lateral edge 42, the first edge 41 being closer to the X axis than the second edge 42. Each opening 4a further comprises two other end edges 43, 44 joining the first edge 41 and the second edge 42. The fins 18 " correspond to the fins located closest to one of the two end edges 43, 44 delimiting the opening 4a. This facilitates the passage of air inside the corresponding opening 4a via the arms 45 separating two successive openings 4a. In the embodiment of FIG. 3b, the fins 18 "'situated opposite an opening 4a have an end extending axially substantially up to the level of the upper face of the rear bearing 4.

In the embodiment of FIG. 1b, the fins 18 "" extend only in relation to a corresponding opening 4a, that is to say that the fins 18 "" are devoid of the portion 181 extending vis-à-vis the solid face of the bearing 4 facing the dissipator 16.

The adjacent fins form radial channels guiding the cooling fluid in the passage 17. Thus, these channels comprise a lower face formed by the rear bearing 4, the two opposite sides of two adjacent fins and the U-bottom of the dissipator 16 formed between two adjacent fins. Advantageously, the fins 18, 18 ', 18 ", 18"', 18 "" are arranged radially in the direction of the flow of the fluid concentrating towards the axial openings 4a of the rear bearing 4. Thus, the power electronics 15 is cooled by conduction, after cooling the dissipator 16 via the fins 18 licked by the air flow along their length.

Furthermore, the dissipator 16 has a main opening 16a to allow the passage of the rotation shaft 2. In the embodiment of Figures 1a and 1b, the main axial opening 16a is configured in such a way that there exists, between this rotation shaft 2 and the dissipator 16, a space 22 through which the air can also circulate. This space 22 forms with the space between the shaft 2 of the power electronics 15 an axial flow channel of the fluid.

Axial openings 1 1 b being made in the bottom of the protective cover 1 1, air is then sucked through these openings 1 1 b in the alternator-starter, then flows through the space 22 along the rotation shaft 2 to join the flow passage 17 under the dissipator 16. Alternatively, as shown in FIG. 7, a sensor 23 for measuring the angular position of the rotation shaft 2 is positioned around the rotation shaft 2. In this case, the position sensor 23 is a resolver closing the opening 16a along the entire periphery of the rotor shaft 2.

In this case, the dissipator 16 includes ventilation openings 16b also visible in FIG. 6, permitting air to pass through axial openings 1 1b of the cover 1 1 towards the axial openings 4a of the rear bearing 4. axial surface of the dissipator 16 licked by the axial air flow inside the machine.

The ventilation openings 16b may have a circular shape as shown in Figures 7 and 8a. In the embodiment of Figure 7, the openings 16b are aligned with each other, while in the embodiment of Figure 8a the openings 16b are positioned circumferentially around the main opening 16a. Thus the openings extend angularly about the axis.

As a variant, the openings 16b may have an elongate shape so as to extend over an angular portion around the rotation shaft 2, in particular aligned with a portion of a circle (see FIG. According to another example not shown, the openings are distributed angularly staggered about the axis X.

In the embodiment of FIGS. 8a and 8b, the dissipator 16 comprises a radial notch 16c for the integration of a Hall effect position sensor which then replaces the resolver. Alternatively, the dissipator 16 has a single vent opening 16b.

Thus, the power electronics 15 is cooled, on the one hand, laterally via the passage 17 and, on the other hand, axially via the passage 22 or the openings 16b to allow the air coming from the outside to reach the passage 17. This additional axial air flow makes it possible to obtain a better cooling of the internal parts of the alternator, such as the buns induced windings, by increasing the overall air flow in the machine.

The coolant flow path at the rear of the starter-alternator is represented by arrows and dashed lines in Figures 1a, 1b, and 6.

Deflectors 24 are placed downstream of the openings 4b made in the rear bearing 4. These deflectors 24 allow the flow of the input fluid to be displaced from the flow of the output fluid so that the fluid leaving the alternator-starter is not not reintroduced immediately in the passage 17. This avoids significant recirculation of the hot fluid from inside the alternator-starter.

These deflectors 24 can be fixed on the bearing 4, near the openings 4b. The deflectors 24 may also be made in the protective cover 1 1, for example, by raising the ends of the protective cover, as shown in Figures 1a, 1b, and 6.

The protective cover 1 1 can wrap the entire rear part of the alternator-starter, that is to say, it envelops the power electronics

Mounted in the dissipator 16 and the entire rear bearing 4. In this case, the protective cover 1 1 may comprise openings located downstream of the lateral openings 4b of the rear bearing 4 and intended to allow the fluid to escape out of the alternator starter.

The dissipator 16 is fixed on the rear bearing 4 by means of tie rods 20. According to one embodiment, the tie rods 20 are the same as those used to fix the bearing usually with the magnetic circuit of the stator 3.

As is clearly visible in FIG. 4, the rear bearing 4 with the dissipator

16 form a mezzanine above the landing 4. The mezzanine is fixed on the bearing 4 by means of the fixing studs 21. These fixing studs 21 are at least two in number. They are distributed between the fins 18. In addition, the electrical machine may comprise a layer of electrically insulating material, placed between the lower face of the dissipator 16 and the rear bearing 4, to avoid any risk of electrical contact between these two elements. Advantageously, this layer of insulating material is fixed on the outer face of the rear bearing 4 and also has air passage openings facing those of the rear bearing 4 for the passage of the cooling fluid.

According to one embodiment, said machine further comprises a brush holder not shown and in that the brush holder is located radially between the rotor and the heat sink, in particular between a plate of the heat sink and the rotor and axially between the bearing and the sensor. position. This saves axial size. According to another embodiment the brush holder not shown is located radially between the rotor and the electronics and axially between the heat sink and the cover.

The cooling device for starter-alternator which has just been described can generally be implemented in any type of alternator, including in particular a rotor with claws or salient poles.

Claims

1. A rotating electric machine (100) operable at least in alternator mode to provide power to a motor vehicle, said rotating electrical machine comprising:

a rear bearing (4),

a rotor (1) fixed on a rotation shaft (2) supported by at least the rear bearing (4),

a stator (3) surrounding said rotor (1), said stator (3) comprising an armature winding (7) comprising windings constituting phases of the electric machine,

said rear bearing (4) having lateral openings (4b) for outputting a cooling fluid, and at least one axial opening (4a) for entering the cooling fluid into said stator (3),

an electronic circuit (15) of power electrically connected to the phase windings of said stator (3),

a heat sink (16) comprising on the one hand a first face on which said electronic power circuit (15) is mounted, and, on the other hand, a second face, opposite to said first face and oriented towards said rear bearing; (4)

a protective cover (1 1) comprising at least one axial opening (1 1 b),

characterized in that said heat sink (16) comprises at least one main opening (16a) for the passage of said rotation shaft (2) and at least one vent opening (16b) allowing the cooling fluid to pass from said axial opening (1 1 b) of said cover (1 1) to said axial opening (4a) of said rear bearing (4).

2. rotary electric machine according to claim 1, characterized in that said heat sink (16) comprises a plurality of ventilation apertures (16b).

3. A rotary electric machine according to claim 1 or 2, characterized in that at least one vent opening (16b) extends over an angular portion about said rotation shaft (2).

4. rotary electric machine according to any one of claims 1 to 3, characterized in that it comprises a position sensor (23) positioned around said rotation shaft (2) closing at least in part said main opening (16a) .

5. A rotary electric machine according to claim 4, characterized in that said position sensor (23) is a resolver closing said main opening (16a) along an entire periphery of said rotation shaft (2).

6. Rotating electric machine according to claim 4, characterized in that said position sensor (23) is a Hall effect sensor.

7. A rotary electric machine according to claim 4, characterized in that said heat sink (16) comprises a radial notch (16c) for integration of said position sensor (23).

8. rotary electric machine according to any one of claims 1 to 7, characterized in that said rear bearing (4) comprises at least one deflector (24) placed at the outlet of a lateral opening (4b) of said rear bearing (4). ).

9. rotary electric machine according to any one of claims 1 to 8, characterized in that said protective cover (1 1) covers said electronic power circuit (15) and the dissipator (16).

10. Rotating electrical machine according to claims 8 and 9, characterized in that said protective cover (1 1) comprises at least one end raised to form said deflector (24).

1 1. Rotary electric machine according to any one of claims 1 to 10, characterized in that it comprises a cooling fluid flow passage (17) between an upper face of said rear bearing (4) facing said heat sink ( 16) and the second face of said heat sink (16), and in that the second face of said heat sink (16) has cooling fins (18, 18 ', 18 ", 18", 18 "") , and in that at least one axial end of a fin (18) extends axially at least up to the level of the upper face of said rear bearing (4).

12. Rotating electrical machine according to claim 1 1, characterized in that at least one fin (18, 18 "") comprises a portion (182) located inside said axial opening (4a) of said rear bearing (4). ).

13. A rotary electric machine according to claim 1 1 or 12, characterized in that said fin (18 "") extends only vis-à-vis said axial opening (4a) of said rear bearing (4).

14. A rotary electric machine according to any one of claims 1 1 to 13, characterized in that the at least one fin (18) further comprises a portion (181) vis-à-vis the full upper face of said rear bearing (4).

15. A rotary electric machine according to any one of claims 1 1 to 14, characterized in that it further comprises at least one second fin (18 ") located vis-à-vis said axial opening (4a) of said rear bearing (4) and remote from the upper face of said rear bearing (4).