WO2017134372A1

WO2017134372A1 - Rotary electric machine fitted with cooling fins

Info

Publication number: WO2017134372A1
Application number: PCT/FR2017/050202
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: FR3047360B1; FR3047360A1; JP6858794B2; JP2019503644A; DE112017000617T5

Abstract

The invention chiefly relates to a rotary electric machine (100) capable of operating at least in alternator mode to supply power to an automotive vehicle, said rotary electric machine including: -a power electronic circuit (15) electrically connected to the phase windings of the stator (3); -a heat sink (16) including, on the one hand, a first face on which said power electronic circuit (15) is mounted and, on the other hand, a second face opposite said first face and oriented towards said rear bearing (4); -a passage (17) for the flow of coolant between an upper face of said rear bearing (4) oriented towards said heat sink (16) and the second face of said heat sink (16), characterized in that the second face of said heat sink (16) includes cooling fins (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).

Description

ROTATING ELECTRIC MACHINE PROVIDED WITH FIN

COOLING

The invention relates to a rotary electric machine provided with cooling fins. 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. In addition, to increase the heat exchange surface, fins are positioned in the fluid flow passage.

The problem lies in the fact that the length of the cooling fins is limited, insofar as it is necessary to ensure a space between the fins and the opposite side of the rear bearing to allow assembly of the assembly without risk of breakage . In other words, the axial extension of the fins would imply a larger size of the electric machine due to the need to always maintain a predefined minimum mounting clearance. 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 cooling fluid flow passage between an upper face of said rear bearing oriented towards said heat sink and the second face of said heat sink,

characterized in that the second face of said heat sink has 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.

The invention thus makes it possible, without increasing the axial size of the electric machine, to increase the exchange surface by elongation of the fins and thus to improve the cooling of the electric machine.

According to one embodiment, the at least one fin comprises a base vis-à-vis the opening and comprises its axial end which extends axially at least to the level of the upper face of said rear bearing. This makes it possible to mount the heat sink without risk that the fins touch the rear bearing.

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

This makes it possible to have a portion of the fin in a zone of acceleration of the fluid and thus may allow better cooling of the fin.

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. This makes it possible to have a larger fin surface of the dissipator.

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. This facilitates the passage of air inside the electric machine. According to an embodiment of the example of the preceding embodiment, said axial opening of said rear bearing is delimited by a first and a second lateral edge, said first lateral edge being closer to an axis of said rotor than the second lateral edge and by two other end edges joining said first side edge and said second side edge, and said second fin is one of the fins closest to one of the two end edges.

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 reduces the looping of the hot air, that is to say, to avoid re-suck the hot air out through the radial openings of the bearing.

According to one embodiment, said rotating electrical machine comprises a protective cover covering said electronic power circuit and said heat sink. According to one embodiment, said protective cover comprises at least one end raised to form said deflector.

According to one embodiment, said protective cover comprises at least one axial opening for the passage of the fluid.

According to one embodiment, said heat sink comprises at least one main opening for the passage of said rotation shaft and at least one ventilation opening allowing air to pass from said axial opening of said cover to said axial opening of said rear bearing. This allows fresh air to enter the machine through the axial opening of the hood, to reduce the temperature of the air injected into 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 air. Thus, the dissipating 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 a circular 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 one embodiment, said rotating electrical 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. 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 fluid The other wall of this passage 17 is formed by the upper face of the rear bearing 4 facing towards the heat sink 16. The protective cover 1 1 has openings 1 1 a located in In this way, the cooling fluid, and in particular the air, is introduced into the rear of the alternator-starter 100 laterally through these openings 1 1a and then circulates in the direction of flow. 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 the suction of air, or any other fluid, to the interior of the passage 17. The air flows ve rs of the 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 defining 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. embodiment of Figure 1b, the fins 18 "" extend only vis-à-vis a corresponding opening 4a, that is to say that the fins 18 "" are devoid of the portion 181 extending towards 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.

Alternatively, the openings 16b may have an elongated shape so as to extend over a circular portion about the rotation shaft 2 (Figure 8b).

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 windings of the induced windings, by an increase in the overall air flow rate 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 portion of the alternator-starter, that is to say it envelops the power electronics 15 mounted on the dissipator 16 and the entire rear bearing 4. In 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 let the fluid escape from 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 bearing 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.

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 power circuit (15) 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 coolant 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),

characterized in that the second face of said heat sink (16) has cooling fins (18, 18 ', 18 ", 18"', 18 ""), and at least one axial end of a fin (18) extends axially at least to the level of the upper face of said rear bearing (4).

2. A rotary electric machine according to claim 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). .

3. rotary electric machine according to claim 1 or 2, characterized in that said fin (18 "") extends only vis-à-vis said axial opening (4a) of said rear bearing (4).

4. rotary electric machine according to any one of claims 1 to 3, characterized in that the at least one fin (18) further comprises a portion (181) vis-à-vis the upper upper face of said bearing rear (4).

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

Rotary electric machine according to claim 5, characterized in that said axial opening (4a) of said rear bearing (4) is delimited by a first and a second lateral edge (41, 42), said first lateral edge (41) being closer to an axis (X) of said rotor (1) than the second lateral edge (42) and by two other end edges (43, 44) joining said first lateral edge (41) and said second lateral edge (42). ), and in that said second fin (18 ") is one of the fins closest to one of the two end edges (43, 44).

7. rotary electric machine according to any one of claims 1 to 6, 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). ).

8. rotary electric machine according to any one of claims 1 to 7, characterized in that it comprises a protective cover (1 1) covering said electronic power circuit (15) and said heat sink (16).

9. rotary electric machine according to claims 7 and 8, characterized in that said protective cover (1 1) comprises at least one end raised to form said deflector (24).

10. Rotary electrical machine according to claim 8 or 9, characterized in that said protective cover (1 1) comprises at least one axial opening (1 1 b) for the passage of the fluid.

1 1. Rotary electric machine according to claim 10, 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 ventilation 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).

12. Rotating electrical machine according to claim 1 1, characterized in that said heat sink (16) has a plurality of ventilation apertures (16b).

13. A rotary electric machine according to claim 1 1 or 12, characterized in that at least one vent opening (16b) extends over a circular portion about said rotation shaft (2).

14. A rotary electric machine according to any one of claims 1 1 to 13, characterized in that it comprises a position sensor (23) positioned around said rotation shaft (2) closing at least in part said main opening (16a). ).

15. A rotary electrical machine according to claim 14, characterized in that said position sensor (23) is a resolver closing said main opening (16a) along an entire periphery of said rotation shaft (2).