WO2016189229A1

WO2016189229A1 - Rotary electric machine provided with a cooling circuit

Info

Publication number: WO2016189229A1
Application number: PCT/FR2016/051190
Authority: WO
Inventors: Lilya Bouarroudj; Michel Fakes; Régis SEIDENBINDER
Original assignee: Valeo Equipements Electriques Moteur
Priority date: 2015-05-20
Filing date: 2016-05-19
Publication date: 2016-12-01
Also published as: FR3036552B1; FR3036552A1

Abstract

The invention relates mainly to a rotary electric machine (10) comprising a rotor (12) mounted on a shaft (13), characterized in that said shaft (13) is provided with at least one outlet hole (33) for a coolant, notably a cooling oil, in relation with a central bore (32) having an oil passage cross section (Sh, Shmin, Shmax) of between 0.00000315 m² and 0.000201m², and preferably measuring of the order of 0.00005026 m².

Description

ROTATING ELECTRIC MACHINE HAVING A CIRCUIT OF

COOLING

The present invention relates to a rotating electrical machine with optimized cooling. The invention finds a particularly advantageous, but not exclusive, application with high power reversible electrical machines that can operate in alternator mode and in motor 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 and may belong to a rotating electrical machine in the form of an alternator, an electric motor, or a reversible machine that can operate in both modes.

The stator is mounted in a housing configured to rotate the shaft for example by means of bearings. The rotor comprises a body formed by a stack of sheets of sheets held in package form by means of a suitable fastening system, such as rivets axially passing through the rotor body from one side to the other. The rotor comprises poles formed for example by permanent magnets housed in cavities formed in the magnetic mass of the rotor, as described for example in document EP0803962. 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. These windings are polyphase windings connected in star or delta whose outputs are connected to a voltage rectifier bridge. In certain types of motor vehicle traction chains, a reversible power machine of high power is coupled to the vehicle gearbox. The electric machine is then able to operate in an alternator mode to provide, in particular, power to the battery and to the on-board vehicle network, and in a motor mode, not only to start the engine, but also to participate pulling the vehicle alone or in combination with the engine. Given its high power between 10kW and 50kW, the electric machine tends to heat up during operation. The aim of the invention is to optimize the cooling of this type of machine, in particular at the level of the stator winding in which currents of high intensity circulate.

For this purpose, the invention relates to a rotary electrical machine comprising a rotor mounted on a shaft and stator surrounding the rotor, the stator comprising a stator body in particular in the form of a sheet package, the stator body defining a cylindrical outer wall, characterized in that a portion of the outer wall of the stator body forms an outer wall of said electrical machine and in that the electric machine comprises a cooling circuit having at least one hole in the shaft, for the output a coolant, especially a cooling oil, and a central bore in the shaft, said hole being in fluid relation with a central bore.

Surprisingly, the invention thus makes it possible to improve the performance of the cooling circuit of the machine, thus reducing the thermal resistance of the machine and thus increasing its torque and electrical power. Indeed, for a given flow of coolant entering the machine, the cooling of the machine is thus improved with respect to a cooling circuit ensuring a distribution of the coolant, both in the shaft and in channels separate from the shaft, for example grooves extending between the housing and the stator. According to one embodiment, the electric machine comprises a housing in which is mounted the stator, the housing being configured to rotate the shaft for example by means of bearings.

According to one embodiment, the casing comprises two flanges each disposed at an axial end of the electric machine.

According to one embodiment, the central bore has an oil passage section of between 0.00000315 m ² and 0.000201 m ² , and is preferably of the order of 0.00005026 m ² .

The invention thus makes it possible to improve the performance of the cooling circuit of the machine, thus reducing the thermal resistance of the machine and thus increasing its torque and electrical power.

According to one embodiment, said electric machine comprises a cooling circuit having one or more coolant outlet holes made exclusively in said shaft of said rotor. Surprisingly, for a given coolant flow entering the machine, the cooling of the machine is thus improved with respect to a cooling circuit providing a distribution of the coolant, both in the shaft and in distinct channels of the shaft, for example grooves extending between the housing and the stator. According to one embodiment, a ratio between the oil passage section and a section of said shaft is between 1% and 64% and is preferably 16%.

In one embodiment, a perpendicular plane passing through an axis of a coolant outlet hole intersects a corresponding winding bun. In one embodiment, said shaft has at least two coolant outlet holes.

According to one embodiment, said coolant outlet holes are offset axially with respect to each other so that the coolant passing through one of the exit holes is adapted to water a base of a winding bun and that the coolant passing by the other exit hole is adapted to sprinkle an upper end of said winding bun.

In one embodiment, said coolant outlet holes are distributed angularly in a regular manner along a circumference of said shaft.

In one embodiment, said coolant outlet holes have an identical diameter with respect to each other.

According to one embodiment, said coolant outlet holes are of different diameters with respect to each other. In one embodiment, said coolant outlet holes are positioned on one side of said rotor.

In one embodiment, said coolant outlet holes are positioned on both sides of said rotor.

According to one embodiment, a ratio between a section of said outlet holes situated on an upstream side of said shaft and a section of said outlet holes located on a downstream side of said shaft with respect to a coolant inlet is between 0, 5 and 1 .2. Such a characteristic makes it possible to guarantee a correct supply of the coolant outlet holes on the downstream side. According to one embodiment, said electric machine comprises a coil formed from an enamel-covered wire and in that said coolant outlet hole is positioned in such a way that the cooling liquid exiting said outlet hole comes into direct contact with said enamel coated wire. According to one embodiment, said winding is formed on a body of a stator of said electric machine.

In one embodiment, said coolant outlet hole is positioned such that the coolant comes into direct contact with at least one winding bun. According to one embodiment, a power of the machine may be between 10kW and 50kW.

According to one embodiment, an outer diameter of the rotor is between 8 and 14 cm, in particular between 10 and 12 cm, and is preferably 1 1 cm. According to one embodiment, an outer diameter of the stator is between 10 and 20 cm, in particular between 13 and 18 cm, and is preferably 15 cm.

According to one aspect, the invention furthermore relates to a rotary electric machine comprising a rotor mounted on a shaft, characterized in that said shaft is provided with at least one exit hole of a cooling liquid, in particular a cooling oil. in relation to a central bore having an oil passage section of 0.00000315 m ^{2 to} 0.000201 m ² and preferably of the order of 0.00005026 m ² .

The foregoing features apply alone or in combination with this aspect of the invention. 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 1 is a longitudinal sectional view of a rotary electric machine according to the present invention; Figure 2 is a perspective view of the shaft of the rotating electrical machine according to the present invention;

Fig. 3a is a longitudinal sectional view of the shaft of the electric machine according to the present invention illustrating a first embodiment of the coolant outlet holes; Fig. 3b is a longitudinal sectional view of the shaft of the rotating electrical machine according to the present invention illustrating a second embodiment of the coolant outlet holes.

Identical, similar or similar elements retain the same reference from one figure to another. FIG. 1 shows a rotating electrical machine 10 comprising a stator

1 1 polyphase surrounding a rotor 12 X1 axis mounted on a shaft 13. The stator January 1 is carried by a housing 14 configured to rotate the shaft 13 via ball bearings. The stator 1 1 of the machine 10 surrounds the rotor 12 with the presence of an air gap between the inner periphery of the stator January 1 and the outer periphery of the rotor 12. The rotor 12 is mounted on the shaft 13 by fitting into a zone 15 The shaft 13 may be subjected to a heat treatment in order to obtain sufficient surface hardness.

This electric machine 10 can be coupled to a gearbox 16 belonging to a motor vehicle traction chain. The machine 10 is then able to operate in an alternator mode to supply, in particular, power to the battery and to the vehicle electrical system, and in a motor mode, not only to start the engine of the vehicle, but also to to participate in the traction of the vehicle alone or in combination with the engine.

For this purpose, the shaft 13 comprises a pinion 17 at one end intended to mesh with a corresponding gear of the gearbox 16. The pinion 17 may for example be mounted on the shaft 13 by cooperating with a fluted inner periphery of the pinion 17 and a corresponding fluted portion 18 of the shaft 13, clearly visible in Figure 2. The cooperation of the longitudinal grooves of the section 18 and the pinion 17 is used to rotate the pinion 17 with the shaft 13.

The power of the machine 10 may be for example between 10kW and 50kW. In an exemplary embodiment, an outer diameter of the rotor 12 is between 8 and 14 cm, in particular between 10 and 12 cm, and is preferably 1 1 cm. An outside diameter of the stator January 1 is between 10 and 20 cm, especially between 13 and 18 cm, and is preferably 15 cm.

More specifically, the rotor 12 comprises a body 19 in the form of a plate package to reduce the eddy currents. Permanent magnets 20 are implanted in openings of the body 19. The magnets 20 may be rare earth or ferrite depending on the applications and the desired power of the machine 10. Alternatively, the rotor poles

12 may be formed by coils. Furthermore, the stator January 1 comprises a body 23 in the form of a pack of sheets with notches, for example of the semi-closed type, equipped with notch insulation for mounting the coil 24. The coil 24 comprises a set phase windings passing through the notches of the body 23 of the stator January 1 and forming a front bun 25a located on the side of the pinion 17 and a rear bun 25b located on the opposite side projecting on either side of the body 23 of the stator 1 1.

The phase windings are obtained for example from a continuous wire covered with enamel. Alternatively, the phase windings are made from conductive elements in the form of pins connected together for example by welding. These windings are, for example, three-phase windings connected in a star or in a triangle. The outputs of the phase windings are connected to a rectifier bridge and / or inverter comprising electronic components, such as diodes or MOSFET type transistors, especially when it is a reversible machine.

The electrical machine 10 is cooled by means of a cooling circuit 28 arranged to allow in particular the flow of a coolant, in this case oil, between the casing 14 and the body 23 of the stator 1 1 , in the direction of the axis X1. For this purpose, the cooling circuit 28 comprises a pump 29 for conveying the oil, in a distribution chamber 30 formed in the housing 14, which allows the oil to circulate inside grooves 31 ' extending axially along the stator January 1 and angularly distributed regularly on the circumference of the stator January 1.

The cooling circuit 28 operates in closed loop, so that the oil is taken by the pump 29 in a reservoir 39 and is recovered after circulation in the machine 10 in the reservoir 39.

In addition, in order to improve its performance, the cooling circuit 28 is configured in such a way that the oil comes into direct contact with the enamel coated wire of the winding 24. By direct contact is meant an oil projection directly from an oil outlet to the enamelled wire without the oil coming into contact with an intermediate element, such as a projection blade of liquid, a deflector or the rotor 12, before coming into contact with the winding wire 24.

For this purpose, as is clearly visible in FIGS. 3a and 3b, the oil flows in an axial bore 32 made in the shaft 13 of the rotor 12 and in the outlet holes 33 coming from the bore 32 having an axis X2 of radial orientation and opening opposite the two buns 25a, 25b of the coil 24, that is to say that each plane P1 perpendicular to the axis X1 of the rotor 12 passing through an axis X2 of an exit hole 33 coolant cut a corresponding bun 25a, 25b (see Figures 1 and 3a). In this case, the central bore 32, of blind configuration, has an inlet 34 of coolant corresponding to the open end of the bore 32 formed on the side of an axial end of the shaft 13. The liquid inlet 34 is situated at the axial end of the shaft 13 on the side of which the pinion 17 is positioned. However, as a variant, the liquid inlet 34 can be made on the side opposite to the pinion 17.

The coolant outlet holes 33 are positioned on both sides of the rotor 12. Such a configuration thus makes it possible, in view of the pressure and the centrifugal force generated by the rotation of the shaft 13, to project the liquid from cooling directly on the two buns 25a, 25b of the rotor 12.

In order to ensure compatibility between oil and enamel to prevent deterioration of the enamel and therefore short circuits, the enamel is made of a material chosen from one of the following materials: polyamide or polyamide; imide. The oil is selected from hydraulic fluids, including gearbox transmission oils with single clutch or dual clutch or automatic. The enamel thickness is between 0.1 and 0.3mm.

Advantageously, as shown in Figure 1, on each side of the rotor 12, the shaft 13 has two outlet holes 33 of coolant. As illustrated in Figure 3a, the outlet holes 33 located on the same side of the rotor 12 may have X2 axes aligned relative to each other. However, advantageously, as illustrated in FIG. 3b, the outlet holes 33 situated on one and the same side of the rotor 12 are offset axially with respect to each other by a distance L1, so that the cooling liquid originating from one outlet holes 33 is adapted to water a base of a bun 25a, 25b (located on the side of the body 23 of the stator January 1) and that the coolant from the other hole 33 is adapted to water a high end the bun 25a, 25b (located on the opposite side of the body 23 of the stator 1 1). The two holes 33 located on the same side of the rotor 12 are preferably diametrically opposite one another.

In a variant, as shown in FIG. 2, the shaft 13 has more than two holes 33 on each side of the rotor 12 which are distributed angularly in a regular manner along a circumference of the shaft 13.

In an advantageous embodiment, the cooling circuit 28 is devoid of grooves 31 and the corresponding distribution chamber 30. The exit holes 33 of coolant are then made exclusively in the shaft 13 of the rotor 12. In fact, it has surprisingly been found that for a given oil flow entering the machine, the cooling of the machine is improved with a circuit 28 providing only a projection of oil on the buns 25a, 25b, through the holes 33 made in the shaft 13, relative to a circuit 28 ensuring a distribution of available oil between the holes of output 33 of the shaft 13 and the grooves 31.

In a preferred embodiment, the diameter L2 (see FIG. 3a) of the shaft 13 in the fitted zone 15 of the rotor 12 is of the order of 20 mm. The section Sar of the shaft 13 without bore is therefore of the order of 0.000314m ² . Furthermore, the diameter L3 of the central bore 32 in the fitted zone 15 is of the order of 8 mm, which corresponds to a passage section of the oil Sh of the order of 0.00005026m ² . Thus, the preferential ratio R1 between the passage section of the oil Sh and the section Sar of the shaft 13 is of the order of R1 = Sh / Sar = 16%. The central bore 32 being made by a deep drilling technique, it is necessary to provide a minimum material thickness radius for the mechanical strength of the order of 2mm. The maximum diameter L3 of the bore 32 is therefore of the order of 16 mm, which corresponds to a passage section maximum oil value Shmax = 0.000201 m ² , a maximum ratio of R1 max = Shmax / Sar = 64%.

Furthermore, the minimum diameter L3 of the central bore 32 is of the order of 1 mm, which corresponds to a minimum oil passage section of Shmin = 0.00000315 m ² , a minimum ratio of R1 min. = Shmin / Sar = 1%. The ratio R1 is therefore between 1% and 64%.

In addition, the diameter L4 of an outlet hole 33 is of the order of 2.4 mm, so that the section Ss of a small output is Ss = 4.52E-6m ² . As a result, the section of the four exit holes 33 (two on each side of the rotor 12) S4s = 1.81 E-5 m ² . A preferential ratio R2 between the section S4s of the outlet holes 33 and the passage section Sh of the oil is therefore S4s / Sh = 36%.

The exit holes 33 are made by a standard drilling method for making holes of any size. It will thus be possible, for example, to produce eight exit holes 33 having a minimum diameter L4 of the order of 0.3 mm. In all cases, the maximum diameter L4 of the exit holes 33 is less than 4 mm, regardless of the number of holes 33.

In addition, a ratio R3 between a section Ss_am of the outlet holes 33 on the upstream side of the shaft 13 (that is to say on the side of the inlet 34 of coolant) and a section Ss_av holes of output 33 on the downstream side of the shaft 13 (i.e. the opposite side of the coolant inlet 34) R3 = Ss_am / Ss_av is between 0.5 and 1 .2. Such a characteristic makes it possible to guarantee a correct supply of the exit holes 33 in cooling liquid on the downstream side. The exit holes 33 present in this case an identical diameter L4 with respect to each other. However, alternatively, the outlet holes 33 may be of different diameters L4 with respect to each other.

Advantageously, a ratio between an electrical power of the machine 10 expressed in kW and a flow rate of the coolant inside the circuit 28 expressed in Liters / min is between 0.3 and 10, especially between 0.5 and 4. The flow of coolant is considered inside the central bore 32.

Preferably, the electrical power of the machine is about 14kW, said ratio is between 1, 16 and 2.33 and the flow rate of coolant is between 6 and 12 L / min.

Alternatively, the exit holes 33 are positioned on one side of the rotor 12.

In another variant, a single outlet hole 33 is positioned on one side of the rotor 12.

Alternatively, the rotor 12 is a wound rotor and the coolant outlet holes 33 are made in the shaft 13 so as to directly water the buns of the wound rotor 12 and / or the stator January 1 to ensure effective cooling of the machine.

Of course, the foregoing description has been given by way of example only and does not limit the scope of the invention which would not be overcome by replacing the different elements by any other equivalent.

Claims

1. Rotary electric machine (10) comprising a rotor (20) mounted on a shaft (13) and stator (1 1) surrounding the rotor (20), the stator (1 1) having a stator body (23) (1 1) in particular in the form of a pack of sheets, the stator body (23) defining a cylindrical outer wall, characterized in that a portion of the outer wall of the stator body (1 1) forms a wall external of said electric machine (10) and in that the electric machine (10) has a cooling circuit (28) having at least one hole (33) in the shaft (13), for the output of a cooling fluid, in particular a cooling oil, and a central bore (32) formed in the shaft (13), said hole (33) being in fluid relation with a central bore (32), the central bore ( 32) including a section (Sh, Shmin, Shmax) of oil passage between 0.00000315 m ² and 0.000201 m ² .

Rotary electric machine according to claim 1, characterized in that the cooling circuit (28) has one or more coolant outlet holes (33) made exclusively in said shaft (13) of said rotor (12).

3. rotary electric machine according to claim 1 or 2, characterized in that a ratio (R1) between the oil passage section (Sh) and a section (Sar) of said shaft (13) is between 1% and 64% and is preferably 16%.

Rotary electric machine according to any one of claims 1 to 3, characterized in that a perpendicular plane (P1) passing through an axis of an outlet hole (33) of coolant cuts a bun (25a, 25b) of corresponding winding.

5. Rotating electrical machine according to any one of claims 1 to 4, characterized in that said shaft (13) has at least two outlet holes (33) of coolant.

Rotary electric machine according to claim 5, characterized in that said coolant outlet holes (33) are axially offset with respect to each other such that the coolant passing through one of the outlet holes (33) is adapted to water a base of a winding bun (25a, 25b) and the coolant passing through the other outlet hole (33) is adapted to sprinkle an upper end of said winding bun (25a, 25b).

7. A rotary electric machine according to claim 5 or 6, characterized in that said coolant outlet holes (33) are distributed angularly in a regular manner along a circumference of said shaft (13).

8. rotary electric machine according to any one of claims 5 to 7, characterized in that said exit holes (33) of coolant have a diameter (L4) identical to each other.

9. rotary electric machine according to any one of claims 5 to 7, characterized in that said exit holes (33) of coolant are of diameters (L4) different from each other.

10. A rotary electric machine according to any one of claims 5 to 9, characterized in that said coolant outlet holes (33) are positioned on one side of said rotor (12).

1 1. Rotary electric machine according to any one of claims 5 to 9, characterized in that said coolant outlet holes (33) are positioned on both sides of said rotor (12).

12. Rotating electric machine according to claim 1 1, characterized in that a ratio (R3) between a section (Ss_am) of said outlet holes (33) located on an upstream side of said shaft (13) and a section (Ss_av ) said outlet holes (33) located on a downstream side of said shaft (13) relative to an inlet (34) of coolant is between 0.5 and 1 .2.

13. A rotary electric machine according to any one of claims 1 to 12, characterized in that it comprises a coil (24) formed from an enamel covered wire and in that said exit hole (33) coolant is positioned such that the coolant exiting said outlet hole (33) comes into direct contact with said enamel coated wire.

14. A rotary electric machine according to claim 13, characterized in that said coil (24) is formed on a body (23) of a stator (1 1) of said electric machine.

Rotary electric machine according to claim 14, characterized in that said coolant outlet hole (33) is positioned in such a way that the coolant comes into direct contact with at least one bun (25a, 25b) of winding.