EP4059122A1

EP4059122A1 - Liquid cooling machine

Info

Publication number: EP4059122A1
Application number: EP20817455.7A
Authority: EP
Inventors: Guillaume TARDY; Diana FANTUZ
Original assignee: Nidec PSA Emotors SAS
Current assignee: Nidec PSA Emotors SAS
Priority date: 2019-11-14
Filing date: 2020-11-04
Publication date: 2022-09-21
Also published as: WO2021094670A1; FR3103332A1; US20220399770A1; FR3103332B1; CN114731079A

Abstract

The invention relates to a rotary electric machine with liquid cooling, comprising a rotor with permanent magnets and a wound stator, the rotor comprising: (i) at least one rotor sheet stack, (ii) magnets housed in the sheet stack, and (iii) front and rear flanges adjacent to the sheet stack, the machine being configured to enable a cross-flow of the cooling liquid within the rotor sheet stack.

Description

Title: Liquid cooling machine Technical field

The present invention relates to rotating electrical machines, and more particularly those cooled by a circulation of a liquid, in particular oil, circulating at least partially along the shaft of the machine.

The invention relates more particularly to synchronous or asynchronous machines with alternating current. It relates in particular to traction or propulsion machines for electric motor vehicles (Battery Electric Vehicle) and / or hybrids (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle), such as passenger cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and / or energy production applications, in particular naval, aeronautical or wind turbines.

Prior art

It is known practice to cool the heads of the stator coils with a cooling liquid ejected by the rotor onto them during the operation of the machine.

Application JP2003324901 describes a machine with a permanent magnet rotor in which the cooling liquid is supplied to the rotor by an axial channel, centered on the axis of rotation, circulates through radial channels to other channels extending axially. along the magnets to cool them. Liquid leaves the rotor at the end of these magnet cooling channels, to be sprayed onto stator coil heads. The rotor has a particular arrangement, with a peripheral ring connecting in its middle to the shaft.

Application US2010 / 0194220 discloses another machine with liquid cooling, involving a circulation of liquid within the rotor to cool the magnets. This application mentions a risk of the insulation of the coil heads being removed by the cooling liquid in the event of projection on the latter. To reduce this risk, the rotor has end pieces attached to the packet of ro toric sheets, together forming a passage for the liquid, this passage opening outwards through outlets located radially set back from the radially outer surface of the rotor. Such arrangement increases the number of constituent parts of the machine and complicates its production. In addition, less cooling of the coil heads is penalizing in terms of performance thereof.

US 2019/0068012 discloses a rotor cooled by liquid circulation. The latter is discharged through through openings made in end flanges.

Disclosure of the invention

The invention aims to improve the cooling of electric machines cooled by circulating liquid.

Summary of the invention

The invention aims to meet this need and it achieves it by means of a rotating liquid-cooled electric machine comprising a rotor with magnets and a wound stator, the rotor comprising:

(i) at least one package of rotor plates,

(ii) magnets housed in said package of sheets,

(iii) front and rear flanges adjacent to said packet of sheets, the machine being configured to provide cross circulation of coolant within the packet of rotor sheets.

In particular, the liquid can circulate in cooling channels of the packet of rotor plates which are angularly offset around the axis of rotation, the cooling channels in which the liquid circulates backwards preferably alternating with those in which the liquid flows forward, these cooling channels preferably being parallel and associated with respective poles of the rotor.

Preferably, the machine comprises a supply of coolant to the front and rear flanges, the liquid supplying the front flange circulating from the latter through the pack of sheets by at least one cooling channel towards the rear flange before leaving the rotor. by at least one evacuation channel delimited at least partially by the rear flange, and the liquid supplying the rear flange circulating from the latter to the front flange via at least one cooling channel of the pack of sheets before leaving the rotor through the minus one evacuation channel delimited at least partially by the front flange. The discharge channels preferably open opposite the heads of the stator coils, in order to allow the projected liquid to cool them.

The invention allows the machine to be cooled while limiting the force with which the coolant impacts the stator. The manufacture of the machine remains simple, and the flanges can be made simply, if desired, in one piece. The invention achieves balanced cooling along the longitudinal axis of the machine.

The front flange may be the one located on the side of the rotor shaft that mechanically engages the driven elements, and that side of the shaft may have a drive pinion, for example machined with the shaft.

Preferably, the front and rear flanges each bear axially against said pack of rotor plates at one end. Thus, the aforementioned discharge channels can be formed recessed on the face of the flange facing said package of rotor plates. Each flange may include at least one supply channel through which the liquid supplying the flange gains at least one cooling channel. This feed channel can be formed in a hollow on the face of the flange facing the package of rotor plates. The feed channels can each be a Y or T shape, or any other suitable shape.

Preferably, the front and rear flanges are identical and angularly offset so as to supply different cooling channels, the cooling channels traversed by the liquid flowing from the front flange to the rear flange preferably being produced within the odd poles, and those traversed by the liquid in the opposite direction, preferably being located within the even poles.

Preferably, the cooling channels are formed by housings receiving magnets, by the space left free by the magnet or magnets in these housings. This space left free can in particular be used to channel the magnetic flux in the sheets of the package.

As a variant, the cooling channels may be other than housings receiving magnets. The cooling channels can for example be formed in recesses used only for cooling, or for other uses, for example for the manufacturing process.

Preferably, the discharge channels have a flared shape towards the outside. The discharge channels can be formed by recesses the depth of which increases as they approach the outer periphery of the flange. Each channel discharge can have a substantially trapezoidal shape. The shape of the discharge channels can limit the rate of ejection of the liquid while still allowing a large area of the stator coil heads to be sprayed.

Preferably, the supply and discharge channels alternate in the circumferential direction on each flange.

The flanges can be fed through the rotor shaft, the rotor shaft possibly having a central channel and radial channels opening onto the aforementioned feed channels of the front and rear flanges. The radial channels feeding the front flange can be angularly offset with respect to those feeding the rear flange, to take account of the angular offset between the flanges.

The machine may include at least one axial channel for distributing the coolant to the flange (s), which may be formed in the rotor mass or between the rotor mass and the shaft, along the shaft. This or these axial distribution channels may pass axially through at least part of the rotor mass. These axial distribution channels can for example be provided in the bundle of sheets and extend flush with the shaft.

The flanges can be supplied with cooling liquid by an axial coolant distribution channel formed in the rotor mass along the shaft. Preferably, each flange is a foundry part, being in particular made of aluminum or an aluminum alloy. The geometry of the flange, with the feed or discharge channels formed at the interface between the flange and the rotor plate pack, allows very simple manufacture without re-machining or drilling. Materials other than aluminum can be used, for example other low-magnetic materials. A further subject of the invention is a method for cooling a rotating electrical machine, the rotor of which comprises a bundle of sheets and magnets housed therein, and the rotor of which rotates within a stator having coil heads. , in particular a machine as defined above, in which the liquid is circulated in opposite directions within the rotor to cool the magnets, then the liquid is sprayed onto the heads of the stator coils after passing through the packet of rotor plates. The circulation through the bundle of sheets can in particular take place crosswise over the entire length of the bundle of sheets, this circulation taking place between the front and rear flanges. The invention makes it possible to cool the stator while limiting the force with which the cooling fluid impacts the stator. The enlarged section of the outlets of the discharge channels prevents the formation of a powerful jet directed towards the stator. Preferably, the liquid circulates axially within the packet, then is ejected radially. The bend formed at the junction between the packet of rotor plates and the flanges breaks the flow, and thus decreases the speed with which the liquid impacts the coils.

Preferably, the cooling fluid is circulated axially within the package of rotor plates through recesses thereof made in the housings of the magnets. Also preferably, all odd poles are cooled by circulation in one direction and all even poles by circulation in the opposite direction.

Brief description of the drawings

The invention may be better understood from reading the following description, of an example of non-limiting implementation thereof, and from examining the appended drawing, in which:

[Fig 1] Figure 1 partially and schematically shows, in longitudinal section, a machine according to the invention,

[Fig 2] FIG. 2 represents the rotor of FIG. 1 in isolation, and illustrates the circulation of the cooling fluid in opposite directions within the package of rotor plates,

[Fig 3] Figure 3 partially and schematically shows the rotor showing a flange in cross section in its thickness,

[Fig 4] Figure 4 shows a detail of the package of rotor plates,

[Fig 5] Figure 5 shows a flange in isolation, and

[Fig 6] Figure 6 illustrates the cooling of the coil heads by the liquid projected by the discharge channels of the flanges on them.

detailed description

The electric machine 1 according to the invention, partially shown in Figure 1, comprises a rotor 10 rotating inside a stator 20 about an axis of rotation X.

The stator 20 comprises a package 21 of stator sheets leaving notches for the electrical conductors of a winding. These conductors project axially from the packet of sheets 21 to form coil heads 22, also called chignons.

The rotor 10 comprises at least one pack 11 of rotor plates carried by a shaft 40 which is guided by bearings (not shown). This shaft 40 carries at the front a pinion 48 which engraine with driven elements, not shown. The end of the shaft 40 carrying the pinion 48 is also called the “drive end”.

The package 11 comprises, as can also be seen in FIG. 4, housings 13 in which permanent magnets 14 are arranged, the magnetization of which can be carried out if necessary after their installation in the housings 13.

The rotor 10 has two front and rear end flanges 30a and 30b arranged against the corresponding ends of the pack 11.

The two flanges 30a and 30b are identical in the example considered, and have, as illustrated in FIG. 5, on their face 31 facing the package 11, a set of recessed reliefs defining circulation passages for a cooling fluid.

This cooling fluid, which is preferably an oil, is supplied through a central channel 41 of the shaft 40, as illustrated in Figure 2.

This channel 41 communicates with the front flange 30a via radial channels 42 and with the rear flange 30b via other radial channels 43 of which only the mouth opening into the central channel 41 can be seen in FIG. 2, these channels 43 being angularly offset with respect to the channels 42.

Referring to Figure 5, we see that each flange 30a or 30b comprises supply channels 32 in the general shape of Y and discharge channels 33 which alternate with the supply channels 33 and open on the outer periphery of the flange.

As can be seen in Figure 3, the supply channels 32 each have a radial branch 32a which is aligned with a radial channel 42 of the shaft 40 and opens onto the latter, and two oblique branches 32b in which are distributes the flow of liquid circulating in branch 32a.

The branches 32b are at least partially superimposed on recesses 16 made in the sheets of the package 11, and forming longitudinal cooling channels 17 through the package 11, as illustrated in Figures 1 and 6.

The recesses 16 are made by cutting the sheets with the housings 13 of the magnets 14, and serve on the magnetic plane to channel the magnetic flux in the sheets of the package 11. The exhaust channels 33 are superimposed on the recesses 16 of the poles located between those which are fed by the supply channels 32.

In the example considered, the rotor has 8 poles, and each flange 30a or 30b has four supply channels 32 and four discharge channels 33. The flanges 30a and 30b are angularly offset by 45 ° in the example considered.

Thus, the channels 17 formed within the package 11 by the recesses 16 of the odd poles are superimposed at one end on the supply channels 32 of the front flange 30a and on the discharge channels 33 of the rear flange 30b, and the channels 17 formed by the recesses of the even poles are superimposed at one end on the discharge channels 33 of the front flange 30a and at the end opposite the supply channels 32 of the rear flange 30b.

This makes it possible to create circulations of the cooling liquid within the rotor in opposite directions.

More precisely, as illustrated in Figures 2 and 3, the liquid arriving through the central channel 41 can reach the front flange 30a through the radial channels 42, then reach through the supply channels 32 the channels 17 of the odd poles and flow from the front to the rear within the bundle of sheets (circulation marked 1 in Figures 2 and 3), before reaching the discharge channels 33 of the rear flange 30b.

The liquid which does not pass through the channels 42 reaches the channels 43 by circulating along the central passage 41, then reaches the rear flange 30b and the supply channels 32 of the latter. The liquid then circulates from the back to the front through the channels 17 of the even-numbered poles (circulation marked 2 in Figures 2 and 3), before reaching the discharge channels 33 of the front flange 30a.

Each discharge channel 33 has a generally substantially trapezoidal shape, with opposite side edges 36 which diverge outwardly, as illustrated in FIG. 5. The angular extent occupied on the periphery of the flange by an discharge channel 33 is for example greater than or equal to 30 ° around the X axis.

The depth of the discharge channel 33, that is to say its distance from which it recedes with respect to the plane of the face 31 of the flange, can increase as illustrated in FIG. 6 with the distance to the center of the flange. .

In Figure 6, we see that the bottom 37 of the discharge channel 33 has a planar shape inclined obliquely away from the package 11.

The angular width of the outlet of the discharge channel 33, as well as the slope of its bottom 37, make it possible to spray coolant on a large portion of the coil heads 22, as shown in Figure 6.

The flanges 30a and 30b are preferably made by casting, in aluminum or an aluminum alloy, and can be held against the package 11 by tie rods, not shown. The faces 31 of the flanges 30a and 30b advantageously cover the magnets 14 and thus contribute to their axial immobilization within the package 31.

The operation of the machine is as follows.

During the rotation of the rotor 10, the cooling liquid circulates in the opposite direction within the pack of sheets, as explained above, and cools the magnets. The liquid leaving the channels 17 formed within the package 11 is sprayed through the discharge channels 33 on the coil heads 22 due to the centrifugal force.

In view of the enlarged section of the outlets of the discharge channels 33, the formation of fine high pressure jets, the impact of which on the coil heads would be liable to damage them, is avoided.

In the example considered, the presence of the bend formed at the junction between the cooling channels 17, axial, and the discharge channels 33, radial, brakes the liquid and further reduces the speed of impact on the coil heads.

The coolant sprayed on the stator can be collected and pumped outside the stator to be cooled before being reinjected by the hollow shaft 40.

Of course, the invention is not limited to the example which has just been described.

The rotor may or may not be twisted.

The rotor can be made with other passages for the coolant. The angular offset between the flanges can be different from 45 °, depending on the polarity of the machine.

Generally speaking, this offset can be 3607n plus the possible twist angle of the rotor, where n denotes the number of poles of the rotor. It may for example be 60 ° for a 6-pole machine.

Preferably all of the poles are cooled, but alternatively only some of them are, for example every other pole or one in four.

The flanges may have a shape other than that illustrated.

Claims

1. Liquid-cooled rotating electric machine (1) comprising a rotor

(10) with magnets (14) and a wound stator (20), the rotor comprising:

(i) at least one package (11) of rotor plates,

(11) magnets (14) housed in said package of sheets,

(iii) the front (30a) and rear (30b) flanges adjacent to said pack (11) of sheets, the machine being configured to ensure cross circulation of the cooling liquid within the pack of rotor sheets, the machine comprising a liquid supply cooling of the front and rear flanges, the liquid supplying the front flange (30a) circulating from the latter through the pack of sheets (11) through at least one cooling channel (17) towards the rear flange (30b) before leaving the rotor by at least one discharge channel (33) delimited at least partially by the rear flange (30b), and the liquid supplying the rear flange (30b) flowing from the latter to the front flange (30a) by at least one cooling channel (17) before leaving the rotor via at least one discharge channel (33) delimited at least partially by the front flange (30a), the front and rear flanges each coming axially to bear against said pack of sheets rotor (11) at one end, and the discharge channels (33) being formed recessed on the face (31) of the flange facing said packet of rotor plates.

2. Liquid-cooled rotating electric machine (1) comprising a rotor

(10) with magnets (14) and a wound stator (20), the rotor comprising:

(i) at least one package (11) of rotor plates,

(11) magnets (14) housed in said package of sheets,

(iii) the front (30a) and rear (30b) flanges adjacent to said pack (11) of sheets, the machine being configured to ensure cross circulation of the cooling liquid within the pack of rotor sheets, the machine comprising a liquid supply cooling of the front and rear flanges, the liquid supplying the front flange (30a) circulating from the latter through the pack of sheets (11) through at least one cooling channel (17) towards the rear flange (30b) before to leave the rotor through at least one discharge channel (33) delimited at least partially by the rear flange (30b), and the liquid supplying the rear flange (30b) flowing from the latter to the front flange (30a) by au at least one cooling channel (17) before leaving the rotor via at least one discharge channel (33) delimited at least partially by the front flange (30a), each flange (30a; 30b) being a foundry part, being in particular made of aluminum or aluminum alloy.

3. Liquid-cooled rotating electric machine (1), comprising a rotor

(10) with magnets (14) and a wound stator (20), the rotor comprising:

(i) at least one package (11) of rotor plates,

(11) magnets (14) housed in said package of sheets,

(iii) the front (30a) and rear (30b) flanges adjacent to said pack (11) of sheets, the machine being configured to ensure cross circulation of the cooling liquid within the pack of rotor sheets, the machine comprising a liquid supply cooling of the front and rear flanges, the liquid supplying the front flange (30a) circulating from the latter through the pack of sheets (11) through at least one cooling channel (17) towards the rear flange (30b) before leaving the rotor by at least one discharge channel (33) delimited at least partially by the rear flange (30b), and the liquid supplying the rear flange (30b) flowing from the latter to the front flange (30a) by at least one cooling channel (17) before leaving the rotor via at least one discharge channel (33) delimited at least partially by the front flange (30a), the flanges being fed by a shaft of the rotor, the tree with a channel central (41), this central channel (41) communicating with the front flange (30a) via radial channels (42) and with the rear flange (30b) via other radial channels (43).

4. Liquid-cooled rotating electric machine (1), comprising a rotor

(10) with magnets (14) and a wound stator (20), the rotor comprising:

(i) at least one package (11) of rotor plates,

(11) magnets (14) housed in said package of sheets,

(iii) front (30a) and rear (30b) flanges adjacent to said package (11) of sheets, the machine being configured to ensure a cross circulation of the cooling liquid within the package of rotor plates, the machine comprising a supply of cooling liquid from the front and rear flanges, the liquid supplying the front flange (30a) circulating from the latter through the latter through the packet of sheets (11) by at least one cooling channel (17) towards the rear flange (30b) before leaving the rotor through at least one discharge channel (33) delimited at least partially by the rear flange (30b) ), and the liquid supplying the rear flange (30b) flowing from the latter to the front flange (30a) through at least one cooling channel (17) before leaving the rotor through at least one discharge channel (33) delimited at least partially by the front flange (30a), the flanges being supplied with cooling liquid by an axial coolant distribution channel formed in the rotor mass along the shaft.

5. Machine according to any one of the preceding claims, with the exception of claim 3, each flange comprising at least one supply channel (32) through which the liquid supplying the flange gains at least one cooling channel (17). .

6. Machine according to claim 5, the feed channel (32) being formed recessed on the face of the flange facing the package (11) of rotor plates.

7. Machine according to one of claims 5 and 6, the feed channels (32) each having a Y or T shape.

8. Machine according to any one of the preceding claims, the front (30a) and rear (30b) flanges being identical and angularly offset so as to supply different cooling channels (17), the cooling channels (17) traversed by the liquid flowing from the front flange to the rear flange preferably being formed within the odd poles, and those through which the liquid passes in the opposite direction, preferably being located within the even poles.

9. Machine according to any one of the preceding claims, the cooling channels being formed by housings (13) receiving magnets (14), by the space (16) left free by the magnet or magnets in these housings.

10. Machine according to any one of the preceding claims, the discharge channels (33) being formed by recesses whose depth increases as they approach the outer periphery of the flange.

11. Machine according to any one of the preceding claims, the supply (32) and discharge (33) channels alternating in the circumferential direction on each flange (30a; 30b).

12. Machine according to the preceding claim, each discharge channel (33) having a substantially trapezoidal shape.

13. Machine according to any one of the preceding claims with the exception of claim 4, the supply of the flanges being effected by a shaft (40) of the rotor.

14. Machine according to any one of the preceding claims, the discharge channels (33) opening opposite the coil heads (22) of the stator.

15. Machine according to any one of the preceding claims with the exception of claim 2, each flange (30a; 30b) being a foundry part, being in particular made of aluminum or an aluminum alloy.

16. A method of cooling a rotating electrical machine as defined in any one of the preceding claims, in which the liquid is circulated in opposite directions within the rotor to cool the magnets, then it is sprayed onto them. stator coil heads the liquid after passing through the rotor plate pack (11).