Rotor for an electric motor provided with a cooling circuit

Abstract

The invention relates to a rotor (10) for an electric motor (30), comprising: - a rotor shaft (12) mounted so as to rotate about an axis (X); - a stack of laminations (14) mounted coaxially on the rotor shaft (12), said stack of laminations (14) comprising first internal cavities (141) housing permanent magnets (15) and second internal cavities (142) extending axially through the entire stack of laminations (14), said second internal cavities (142) housing filling modules (21); - a front flange (17) and a rear flange (19) mounted coaxially on the rotor shaft (12) and arranged axially on either side of the stack of laminations (14) so as to be contiguous with the front and rear side faces (143, 144), respectively, of the stack of laminations (14); and - channels (124, 126, 175, 195, 214) for circulating a cooling fluid formed, respectively, inside the shaft (12), the front and rear flanges (17, 19), and the filling modules (21).

Description

[0001] ROTOR FOR ELECTRIC MOTOR EQUIPPED WITH A COOLING CIRCUIT

[0002] The invention relates to a rotor for an electric motor arranged to allow better evacuation of the heat generated during its operation. The invention also relates to an electric motor comprising such a rotor.

[0003] Generally speaking, current electric motors comprise a rotor secured to a shaft and a stator which surrounds the rotor. The stator is mounted in a casing which comprises bearings for the rotational mounting of the shaft. The rotor comprises a body formed by a stack of laminations or claw poles held in the form of a packet by means of a suitable fastening system. The rotor body comprises internal cavities housing permanent magnets. The stator comprises a body constituted by a stack of laminations forming a crown, the inner face of which is provided with teeth delimiting two by two a plurality of notches open towards the interior of the stator body and intended to receive phase windings. These phase windings pass through the notches of the stator body and form buns projecting on either side of the stator body.The phase windings may, for example, consist of a plurality of U-shaped conductor segments, the free ends of two adjacent segments being connected together by welding.

[0004] In the rotor, the lamination pack is axially sandwiched between a front flange and a rear flange mounted coaxially to the shaft. Each flange has the overall shape of a disc extending in a radial plane perpendicular to the axis of the shaft. Each flange has a central hole for coaxial mounting on the shaft and several through holes intended to receive fixing screws passing axially through the entire lamination pack, said screws being secured to the flanges by means of nuts. The front and rear flanges are generally formed from a non-magnetic, heat-conducting material, for example a metal.

[0005] The housing typically has front and rear bearings assembled together. The bearings define an internal cavity in which the rotor and stator are housed. Each of the bearings centrally carries a ball bearing for rotating the rotor shaft.

[0006] During motor operation, the induced magnetic flux circulating through the rotor generates significant heat that must be removed. Several solutions currently exist to cool the motor. One of these solutions, described in French patent application FR 3 111 025, consists of circulating a cooling fluid through through-cavities formed inside the lamination pack, these through-cavities extending in the axial direction of the rotor. Such through-cavities are generally used to standardize the magnetic field generated by the rotor's permanent magnets. However, this solution proves unsatisfactory from an energy point of view. Indeed, such through-cavities are often oversized compared to the volume of cooling fluid required to ensure good heat removal from the rotor.By circulating a cooling fluid inside these through cavities, it may therefore happen that certain parts of the sheet metal pack which are far from the heat sources, namely the magnets, are unnecessarily cooled by the cooling fluid while certain other parts of the sheet metal pack which are close to said heat sources are insufficiently cooled due to the poor passage of the cooling fluid along these parts. This results in uncontrolled heat dissipation, which can potentially lead to a malfunction of the electric motor.

[0007] The invention therefore aims to propose a rotor and an electric motor comprising such a rotor arranged to allow better evacuation of the heat generated during its operation and not having the drawbacks of the existing solutions described previously.

[0008] For this purpose, the invention relates to a rotor for an electric motor comprising:

[0009] - a rotor shaft mounted to rotate around an axis;

[0010] - a stack of laminations mounted coaxially on the rotor shaft, said stack of laminations comprising first internal cavities and at least two second internal cavities symmetrical with respect to the axis of the shaft and to each other, said second internal cavities passing axially through the entire stack of laminations such that they open, at one of their ends, at a front lateral face of said stack of laminations and, at another of their ends, at a rear lateral face of said stack of laminations, said second internal cavities being configured to allow the circulation of a cooling fluid inside the stack of laminations;

[0011] - a plurality of permanent magnets housed inside the first internal cavities of the sheet metal pack;

[0012] - a front flange and a rear flange mounted coaxially on the rotor shaft and arranged axially on either side of the sheet metal stack so as to be contiguous respectively to the front and rear lateral faces of the sheet metal stack;in which the shaft is provided with at least one first internal channel for circulating a cooling fluid, called the inlet channel, and at least one second internal channel for circulating a cooling fluid, called the outlet channel, and in that the front flange, respectively the rear flange, is configured to form with the front lateral face, respectively the rear lateral face, of the stack of sheets at least two front connecting channels, respectively at least two rear connecting channels, inside which a cooling fluid can circulate, each of said front connecting channels, respectively rear, being in fluid communication with one of said inlet and outlet channels and with one of said second internal cavities;characterized in that the rotor further comprises at least two plastic filling modules, each of said filling modules being intended to be housed in one of said second internal cavities and being configured so as to form, in combination with an internal wall of the sheet metal pack, at least one longitudinal fluid circulation channel opening, at a front end, onto one of the front connecting channels, and, at a rear end, onto one of the rear connecting channels, said at least one longitudinal fluid circulation channel being configured to allow the circulation of a cooling fluid.;

[0013] Thus configured, the rotor of the invention will make it possible to better evacuate the heat generated during its use, due to the passage of a cooling fluid in longitudinal fluid circulation channels formed inside the sheet stack. These longitudinal channels having a smaller volume than that of the second internal cavities, the cooling fluid will circulate optimally inside the sheet stack. In particular, by adequately configuring the filling modules, it will thus be possible to position the longitudinal channels close to the permanent magnets of the rotor, thus circulating the cooling fluid as close as possible to the hot regions of the sheet stack. Better heat evacuation will thus be obtained.Furthermore, circulating the coolant through the end plates generates few changes to the overall structure of the electric motor and, therefore, offers a relatively inexpensive solution to the problem of heat removal in electric motors.

[0014] The rotor of the invention may also include one or more of the following characteristics:

[0015] - each longitudinal fluid circulation channel is defined at least partially by at least one longitudinal groove formed inside a peripheral wall of one of the filling modules, said peripheral wall being in contact with an internal wall of the sheet metal pack which at least partially defines one of the second internal cavities.

[0016] - each longitudinal fluid circulation channel has a serpentine shape.

[0017] - said front connecting channels are in fluid communication with said inlet channel and said rear connecting channels are in fluid communication with said outlet channel, such that a cooling fluid intended for cooling the rotor can circulate in the rotor successively through the inlet channel, then between the front flange and the front lateral face of the sheet stack through said front connecting channels, then inside the sheet stack through said longitudinal fluid circulation channels, then between the rear flange and the rear lateral face of the sheet stack through said rear connecting channels, and finally through the outlet channel.

[0018] - the shaft comprises a hollow front end portion and a hollow rear end portion separated from the front end portion by a solid central portion, the front end portion, respectively the rear end portion, being crossed by a central cavity of cylindrical shape, said central cavity forming the inlet channel, respectively the outlet channel, of the shaft, and at least two holes oriented radially relative to the axis of the shaft are formed inside the front end portion, respectively the rear end portion, so as to open on one side into the inlet channel, respectively the outlet channel, and on the other side into said front connecting channels, respectively said rear connecting channels.

[0019] - said rear connecting channels are in fluid communication with said inlet channel and said front connecting channels are in fluid communication with said outlet channel, such that a cooling fluid intended for cooling the rotor can circulate in the rotor successively through the inlet channel, then between the rear flange and the rear lateral face of the sheet metal stack through said rear connecting channels, then inside the sheet metal stack through said longitudinal fluid circulation channels, then between the front flange and the front lateral face through said front connecting channels, and finally through the outlet channel.

[0020] - the shaft comprises a hollow front end portion and a solid rear end portion separated from the front end portion by a hollow central portion, the front end portion and the central portion being crossed by a central cavity of cylindrical shape, said central cavity forming the inlet channel of the shaft, the front end portion also being crossed by at least one peripheral cavity aligned coaxially with the central cavity, said at least one peripheral cavity forming the outlet channel of the shaft, and at least two holes oriented radially relative to the axis of the shaft are formed inside the front end portion, respectively of the central portion, so as to open on one side into the outlet channel, respectively the inlet channel, and on the other side into said front connecting channels, respectively said rear connecting channels.

[0021] - the shaft comprises a main body provided with a blind hole aligned along the axis of the shaft, said blind hole comprising two contiguous sections of different internal diameters, namely a first section having a first internal diameter and a second section having a second internal diameter, and a plastic insert is housed inside the blind hole at the first section, said insert being formed of a tubular portion aligned with the second section of the blind hole and having an internal diameter which is substantially equal to the second internal diameter, and of an annular portion extending radially around one of the ends of the tubular portion, said annular portion being positioned at the interface between the first section and the second section of the blind hole and having an external diameter which is substantially equal to the first internal diameter,the input channel of the shaft being jointly defined by the tubular part of the insert and by the second section of the blind hole and the output channel of the shaft corresponding to the space delimited by the first section of the blind hole and by the tubular and annular parts of the insert.,

[0022] - the insert comprises one or more separating fins extending radially from the outer periphery of the tubular portion, each of the separating fins being configured to separate the outlet channel into two or more outlet channel segments.

[0023] - each of the front and rear flanges has an internal face in contact with a lateral face of the stack of sheets, said internal face being provided with at least two oblong radial grooves, each of said radial grooves extending radially from a first end opening onto a hollowed-out central zone of said flange, at which said radial groove is in fluid communication with the inlet or outlet channel of the shaft, to a second end opening onto one of the longitudinal fluid circulation channels.

[0024] - each of said radial grooves faces a radial hole formed through the shaft, said radial hole opening on one side onto the inlet or outlet channel of the shaft and on the other side onto the peripheral wall of the shaft.

[0025] - each of the front and rear flanges is provided on its internal face with a circular groove intended to house an annular-shaped sealing gasket, said sealing gasket being intended to ensure sealing between the flange and the sheet metal pack.

[0026] The invention also relates to an electric motor comprising a rotor as defined previously.

[0027] The invention will be better understood upon reading the non-limiting description which follows, given with reference to the attached figures.

[0028] Figure 1 is a truncated perspective view of a rotor-stator assembly according to a first embodiment of the invention.

[0029] Figure 2 is a longitudinal sectional view of the rotor-stator assembly shown in Figure 1.

[0030] Figure 3 is a longitudinal sectional view of an electric motor incorporating the rotor and stator of Figure 1.

[0031] Figure 4 is a perspective view of the rotor lamination pack of Figure 1, equipped with permanent magnets.

[0032] Figure 5 is a perspective view of the rotor filler modules of Figure 1. Figure 6 is a perspective view of the lamination pack of Figure 4 equipped with the filler modules of Figure 5 and permanent magnets.

[0033] Figure 7 is a perspective view of the shaft equipping the rotor of Figure 1.

[0034] Figure 8 is a longitudinal sectional view of the shaft of Figure 7.

[0035] Figure 9 is a front axial view of the shaft of Figure 7.

[0036] Figure 10 is a perspective view of the insert used in the shaft of Figure 7.

[0037] Figure 11 is a perspective view of the outer face of the front flange used in the rotor of Figure 1.

[0038] Figure 12 is a perspective view of the inner face of the flange of Figure 11.

[0039] Figure 13 is a longitudinal sectional view of a shaft equipping a rotor according to a second embodiment of the invention.

[0040] Throughout the description and in the claims, the terms "axial" and "radial" and their derivatives are defined relative to the axis of rotation of the rotor. Thus, an axial orientation refers to an orientation parallel to the axis of rotation of the rotor and a radial orientation refers to an orientation perpendicular to the axis of rotation of the rotor. Furthermore, by convention, the terms "front" and "rear" refer to separate positions along the axis of rotation of the rotor. In particular, the "front" end of the rotor shaft corresponds to the end of the shaft on which a pulley, a pinion, a spline intended to transmit the rotational movement of the rotor to any other similar motion transmission device can be fixed.

[0041] Figures 1 and 2 represent a rotor 10 according to a first embodiment of the invention, the rotor 10 being surrounded by a stator 36 of annular shape. The rotor 10 comprises a substantially cylindrical body formed by a pack of sheets 14 (shown in Figure 4) made of a ferromagnetic material, in particular steel, said body being integral in rotation with a shaft 12 mounted to rotate about an axis X. The rotor 10 further comprises a plurality of permanent magnets 15 intended to be housed in a plurality of first internal cavities 141 formed inside the pack of sheets 14 (see Figure 4) and arranged obliquely to each other, each of the first internal cavities 141 housing one or more permanent magnets 15. The magnets 15 may be made of rare earth for example.In the embodiment shown, the magnets 15 have a parallelepiped shape with a rectangular section and are aligned in two planes perpendicular to the axis X of the shaft 12, each of said planes respectively forming a front lateral face 143 and a rear lateral face 144 of the stack of laminations 14. The magnets 15 are distributed uniformly around the axis X and are arranged so as to form a multi-branched star pattern. The stack of laminations 14 is mounted coaxially on the shaft 12. The shaft 12 may be force-fitted inside a central opening of the stack of laminations 14 so as to connect the rotor body in rotation with the shaft 12.

[0042] The sheet metal stack 14 is formed from an axial stack of sheets extending in a radial plane perpendicular to the axis X of the shaft 12. A plurality of fixing holes 11 are made in the sheet metal stack 14 to allow the passage of fixing screws (not shown). These fixing holes 11 are through holes so that it is possible to pass a screw inside each hole 11. A first end of the screws bears against the external face of a front end flange 17, while the other end of the screws protrudes from the external face of a rear end flange 19 and is threaded so as to receive a nut which, once screwed, exerts pressure against said external face. Thus, the sheet metal stack 14 is axially clamped between the front end flange 17 and the rear end flange 19.These flanges 17, 19 may advantageously ensure balancing of the rotor 10 while allowing good maintenance of the magnets 15 inside the first internal cavities 141. The balancing of these flanges can be carried out by adding or removing material. The removal of material can be carried out by machining, while the addition of material can be carried out by implanting elements in openings provided for this purpose and distributed along the circumference of the flange 17, 19.

[0043] With reference to Figure 3, there is shown an electric motor 30 equipped with the rotor 10 of Figure 1. This electric motor 30 comprises in particular a two-part casing housing the rotor 10 and an annular stator 36 which surrounds the rotor 10 coaxially with the shaft 12. The casing comprises in particular a front bearing 32 and a rear bearing 34 connected to each other, for example by means of fixing screws. The bearings 32, 34 are hollow in shape and each centrally carry a ball bearing, respectively 33 and 35, for the rotational mounting of the shaft 12. Ball ends 37 project axially on either side of the stator body 36 and are housed in the intermediate space separating the stator 36 from the respective bearings 32, 34. The front and rear bearings 32, 34 will advantageously be made of metal.

[0044] As illustrated in Figure 4, the sheet metal pack 14 of the rotor 10 further comprises a plurality of second internal cavities 142 extending in a radial direction relative to the axis X and are axially through. These second internal cavities 142 are configured to house filling modules 21 (as shown for example in Figure 5) made of plastic, each filling module 21 being configured to form, in combination with an internal wall of the sheet metal pack 14 which defines one of the second internal cavities 142, at least one longitudinal fluid circulation channel. In the embodiment shown, these second internal cavities 142 are four in number, namely the cavities 142a, 142b, 142c and 142d. The cavities 142a-142d each have a section in the shape of a portion of a ring and are distributed uniformly around the axis X.Two directly adjacent cavities 142a-142d are separated by a radial segment 18 of the lamination pack 14 so that a central annular portion of the rotor body is made up of alternating second internal cavities 142a-142d and radial segments 18. As shown in FIG. 2, each cavity 142a-142d opens, at one of its ends, at the front lateral face 143 of said lamination pack 14, and, at another of its ends, at the rear lateral face 144 of said lamination pack 14. Each of the front and rear lateral faces 143, 144 faces and is directly adjacent to an internal face 173, 193 of the front and rear flanges 17, 19 respectively.

[0045] As illustrated in Figures 5 and 6, each filling module 21 has a shape substantially complementary to one of the second internal cavities 142 so as to fill it almost completely. Each filling module 21 thus has a semi-cylindrical shape defined in particular by a front wall 211 and a rear wall 213 connected by a curved longitudinal wall 212 which adjoins a corresponding internal wall of the sheet metal stack 14 when the filling module 21 is housed inside one of the second internal cavities 142. The longitudinal wall 212 is provided with two longitudinal grooves 214 extending from a front end 215 located at the front wall 211 to a rear end 216 located at the rear wall 213.These longitudinal grooves 214 are intended to form, in combination with the internal walls of the sheet metal pack 14 adjoining the filling modules 21, longitudinal fluid circulation channels opening, at their front end 215, onto fluid circulation channels 175 (shown for example in FIG. 3) formed at least partially inside the front end plate 17, and, at their rear end 216, onto fluid circulation channels 195 formed at least partially inside the rear end plate 19. Thus configured, these longitudinal fluid circulation channels 214 will make it possible to circulate a cooling fluid inside the rotor 10, while being in contact with a portion of the sheet metal pack 14 which is relatively close to the magnets 15. This will therefore result in better heat dissipation and improved operation of the rotor 10.To further improve heat dissipation, it will be advantageous to increase the contact time of the cooling fluid with the sheet metal pack 14. An advantageous solution consists, for example, as in the specific embodiment shown in FIG. 5, of configuring each longitudinal groove 214 in such a way that it describes a serpentine shape.

[0046] With reference to Figures 7 to 9, the shaft 12 equipping the rotor 10 of Figure 1 is shown. This shaft 12 comprises in particular a main body 120 formed of a front end portion 121 and a rear end portion 123, said front and rear end portions being separated by a central portion 122 (the central portion 122 is delimited by dotted lines in Figure 8). The main body 120 is provided with a blind hole 128 aligned along the axis X of the shaft 12. This blind hole 128 comprises two contiguous sections of different internal diameters, namely a first section 128a having an internal diameter D1 and a second section 128b having an internal diameter D2. A plastic insert 13 is housed inside the blind hole 128 at the first section 128a.As shown in Figure 10, this insert 13 is formed of a tubular part 131, having an internal diameter Di substantially equal to the internal diameter D2, and of an annular part 132 extending radially around one of the ends of the tubular part 131, said annular part 132 having an external diameter De substantially equal to the internal diameter D1. Four fins 133 extend radially from the external periphery of the tubular part 131, said fins 133 being perpendicular two by two. Each of the fins 133 has a length such that its free end is tangent to the outer peripheral edge of the annular portion 132. When the insert 13 is fixed in the main body 120, its tubular portion 131 is aligned with the second section 128b of the blind hole 128 and its annular portion 132 is positioned at the interface between the first section 128a and the second section 128b of the blind hole 128.Thus configured, the shaft 12 has a first channel 124, called the inlet channel, through which a cooling fluid intended to cool the rotor 10 can be conveyed, and at least one second channel 126, called the outlet channel, through which the cooling fluid can exit after having stored the heat coming from the magnets 15 and the pack of sheets 14. The inlet channel 124 is formed jointly by the tubular part 131 of the insert 13 and by the second section 128b of the blind hole 128. The outlet channel 126 is defined by the peripheral space surrounding the tubular part 131 of the insert 13. The outlet channel 126 is thus delimited by the internal wall of the first section 128a of the blind hole 128 and by the tubular and annular parts 131, 132 of the insert 13. This outlet channel 126 is divided respectively into four outlet channel segments 126a, 126b, 126c and 126d, two directly adjacent segments being separated by a fin 133.Furthermore, the shaft 12 is provided with four holes 125 oriented radially with respect to the axis X of the shaft 12, said holes 125 being formed inside the front end portion 121 so as to open, on one side, into one of the segments 126a-126d of the outlet channel 126 and, on the other side, into a central zone 172 of the front flange 17 which communicates with the front connecting channels 175, as shown in FIG. 3. Similarly, four holes 127 oriented radially with respect to the axis X of the shaft 12 are formed inside the central portion 122 so as to open, on one side, into the inlet channel 124 and, on the other side, into a central zone 192 of the rear flange 19 which communicates with the rear connecting channels 195. As explained below, the front and rear connecting channels 175, 195 are formed respectively inside the front and rear flanges 17, 19.With reference to figures 11 and 12, the front flange 17 equipping the rotor 10 of figure 1 is shown. The rear flange 19 having a structure identical to the front flange 17, the technical details given below will apply in a similar manner to the rear flange 19. The front flange 17 is substantially in the form of a disc comprising in particular an external face 171 and an internal face 173. The internal face 173 is in contact with the front lateral face 143 of the stack of sheets 14 (the internal face 193 of the rear flange 19 is on the other hand in contact with the rear lateral face 144 of the stack of sheets 14). The internal face 173 is provided with a series of eight oblong grooves 175 extending radially from a hollowed-out central zone 172 of said flange to an intermediate zone of said flange, the eight grooves 175 being offset by an angle of 45° relative to each other.The external face 171 therefore has several protrusions 178 matching the hollow shape of the underlying grooves 175. Cylindrical section cavities 176 are also provided at the level of the external face 171, each of said cavities 176 being capable of housing the head of a screw intended to connect the front and rear flanges 17, 19. A bore 177 is therefore formed through the front flange 17 to allow the threaded rod of said screw to pass through. Furthermore, each of the front and rear flanges 17, 19 is advantageously provided on its internal face 173, 193 with a circular groove 174, 194 intended to house a sealing gasket 16 of annular shape, said sealing gasket 16 being intended to ensure sealing between the front or rear flange 17, 19 and the pack of sheets 14. For this purpose, the circular groove 174 will be radially further from the central zone 172 than the distal ends 175a of the grooves 175.

[0047] As illustrated in Figure 12, each of the grooves 175 has a distal end 175a and a proximal end 175b. In the mounted position of the front flange 17 shown in Figure 1, the proximal end 175b opens onto the central zone 172 towards which also open the ends 125a of the radial holes 125 of the shaft 12 and the distal end 175a faces the front end 215 of one of the longitudinal channels 214 of one of the filling modules 21. Thus, fluid communication takes place between the radial holes 125 of the shaft 12 and the longitudinal channels 214 via, successively, the central zone 172 and the radial grooves 175 of the front flange 17.Similarly, fluid communication takes place between the radial holes 127 of the shaft 12 and the longitudinal channels 214 via, successively, the central zone 192 and the radial grooves 195 formed at the level of the internal face 193 of the rear flange 19, the distal ends of which face the rear ends 216 of the longitudinal channels 214.

[0048] By convention, the radial grooves 175 are thus called front connecting channels and the radial grooves 195 are called rear connecting channels. Thus configured, the rotor 10 can be cooled by a cooling fluid, such as oil for example, said cooling fluid circulating in the rotor successively through the inlet channel 124 of the shaft 12, then between the rear flange 19 and the rear lateral face 144 of the stack of sheets 14 through the rear connecting channels 195, then inside the stack of sheets 14 through the longitudinal channels 214, then between the front flange 17 and the front lateral face 143 of the stack of sheets 14 through the front connecting channels 175, and finally through the segments 126a-126d of the outlet channel 126 of the shaft 12.

[0049] With reference to Figure 13, there is shown an alternative embodiment of a shaft 12 which can equip a rotor according to the invention. This shaft 12 comprises in particular a hollow front end portion 121 and a hollow rear end portion 123 separated from the front end portion 121 by a solid central portion 122 (the central portion 122 is delimited by dotted lines in Figure 13). The front end portion 121 is crossed by a central cavity 124 of cylindrical shape, said central cavity 124 having a front end 124a open towards the outside and a closed rear end 124b. Near the rear end 124b is formed a series of four holes 125 oriented radially with respect to the axis X of the shaft 12, said holes 125 being arranged at right angles to each other. Each of the holes 125 has an end 125a radially distant from the central cavity 124 and open towards the outside.The front end portion 121 is thus configured to allow the entry of a flow of cooling fluid at the front end 124a of the central cavity 124, then the circulation of said cooling fluid through the central cavity 124 until reaching the radial holes 125, then through the radial holes 125 until reaching the ends 125a of the holes 125. Symmetrically, the rear end portion 123 is crossed by a central cavity 126 of cylindrical shape, said cavity having a rear end 126a open towards the outside and a front end 126b closed. Near the front end 126b is formed a series of four holes 127 oriented radially with respect to the axis X of the shaft 12, said holes 127 being arranged at right angles to each other. Each of the holes 127 has an end 127a radially distant from the central cavity 126 and open towards the outside.The rear end portion 123 is thus configured to allow the entry of a flow of cooling fluid at the ends 127a of the radial holes 127, then the circulation of said cooling fluid through the radial holes 127 until reaching the central cavity 126, then through the central cavity 126 until reaching the rear end 126a of the central cavity 126.

[0050] In the remainder of the description, and by convention, the central cavity 124 will thus be called the inlet channel for the cooling fluid and the central cavity 126 will be called the outlet channel for the cooling fluid. By equipping the rotor 10 of FIG. 1 with the shaft 12 of FIG. 13 instead of the shaft 12 of FIG. 8, it is thus possible to modify the path followed by the cooling fluid inside the rotor 10.In particular, the cooling fluid may circulate in the rotor 10 successively through the inlet channel 124 of the shaft 12, then between the front flange 17 and the front lateral face 143 of the stack of sheets 14 through the front connecting channels 175, then inside the stack of sheets 14 through the longitudinal fluid circulation channels 214, then between the rear flange 19 and the rear lateral face 144 of the stack of sheets 14 through the rear connecting channels 195, and finally through the outlet channel 126 of the shaft 12.

[0051] The invention is obviously not limited to the embodiments as described above. In particular, in other embodiments (not shown) of the invention, the number of second internal cavities 142, and radial holes 125, 127 may differ by four, and the number of front and rear connecting channels 175, 195 may differ by eight.

[0052] Thus, a possible configuration of the invention could consist of a rotor comprising only two second internal cavities 142 arranged symmetrically with respect to the axis X of the shaft 12.

[0053] In another possible configuration of the invention, the rotor may comprise three (or another odd number) second internal cavities 142, said second internal cavities 142 being distributed regularly around the X axis so as not to create an imbalance for the rotor. In particular, the respective centers of gravity of the second internal cavities 142 may form an equilateral triangle in a plane perpendicular to the X axis and the center of gravity of this equilateral triangle will be aligned with the X axis.

[0054] In another possible configuration of the invention, the rotor 10 of FIG. 1 could comprise an insert 13 without separation fins 133. As a result, the outlet channel 126 would not be divided into outlet channel segments 126a-126d, but would consist of a single peripheral cavity aligned coaxially with the central cavity 124 formed by the tubular part 131 of the insert 13.

Claims

DEMANDS 1. Rotor (10) for electric motor (30) comprising: - a rotor shaft (12) mounted to rotate around an axis (X); - a sheet metal pack (14) mounted coaxially on the rotor shaft (12), said sheet metal pack (14) comprising first internal cavities (141) and at least two second internal cavities (142) symmetrical with respect to the axis (X) of the shaft (12) and to each other, said second internal cavities (142) traversing axially through the entire sheet metal pack (14) such that they open, at one of their ends, at the level of a front lateral face (143) of said sheet metal pack (14) and, at another of their ends, at the level of a rear lateral face (144) of said sheet metal pack (14); - a plurality of permanent magnets (15) housed inside the first internal cavities (141) of the sheet metal bundle (14); - a front flange (17) and a rear flange (19) mounted coaxially on the rotor shaft (12) and arranged axially on either side of the sheet metal bundle (14) so ​​as to be contiguous respectively to the front and rear lateral faces (143, 144) of the sheet metal bundle (14);in which the shaft (12) is provided with at least one first internal channel (124) for the circulation of a cooling fluid, called the inlet channel, and at least one second internal channel (126) for the circulation of a cooling fluid, called the outlet channel, and in that the front flange (17), respectively the rear flange (19), is configured to form with the front side face (143), respectively the rear side face (144), of the sheet metal package (14) at least two front connecting channels (175), respectively at least two rear connecting channels (195), within which a cooling fluid can circulate, each of said front connecting channels (175), respectively rear connecting channels (195), being in fluidic communication with one of said inlet and outlet channels (124, 126) and with one of said second internal cavities (142);characterized in that the rotor (10) further comprises at least two plastic filling modules (21), each of said filling modules (21) being intended to be housed in one of said second internal cavities (142) and being configured so as to form, in combination with an internal wall of the sheet metal pack (14), at least one longitudinal fluid circulation channel (214) opening, at a front end (215), onto one of the front connecting channels (175), and, at a rear end (216), onto one of the rear connecting channels (196), said at least one longitudinal fluid circulation channel (214) being configured to allow the circulation of a cooling fluid.; 2. Rotor (10) according to claim 1, characterized in that each longitudinal fluid circulation channel (214) is defined at least partially by at least one longitudinal groove (214) formed inside a peripheral wall (212) of one of the filling modules (21), said peripheral wall (212) being in contact with an internal wall of the sheet metal pack (14) which defines at least partially one of the second internal cavities (142).

3. Rotor (10) according to claim 1 or 2, characterized in that each longitudinal fluid circulation channel (214) has a serpentine shape.

4. Rotor (10) according to any one of claims 1 to 3, characterized in that said front connecting channels (175) are in fluidic communication with said inlet channel (124) and said rear connecting channels (195) are in fluidic communication with said outlet channel (126), such that a cooling fluid for cooling the rotor can circulate in the rotor successively through the inlet channel (124), then between the front flange (17) and the front side face (143) of the sheet metal stack (14) through said front connecting channels (175), then inside the sheet metal stack (14) through said longitudinal fluid circulation channels (214), then between the rear flange (19) and the rear side face (144) of the sheet metal stack (14) through said rear connecting channels (195), and finally through the outlet channel (126).

5. Rotor (10) according to claim 3, characterized in that the shaft (12) comprises a hollow front end portion (121) and a hollow rear end portion (123) separated from the front end portion (121) by a solid central portion (122), the front end portion (121) and the rear end portion (123) respectively, being traversed by a central cylindrical cavity, said central cavity forming the inlet channel (124) and the outlet channel (126) respectively of the shaft (12), and in that at least two holes (125, 127) oriented radially with respect to the axis (X) of the shaft (12) are formed inside the front end portion (121) and the rear end portion (123) respectively, so as to open on one side into the inlet channel (124) and the outlet channel (126) respectively. (126), and on the other side in said front link channels (175), respectively said rear link channels (195).

6. Rotor (10) according to any one of claims 1 to 3, characterized in that said rear link channels (195) are in fluidic communication with said inlet channel (124) and said front connecting channels (175) are in fluidic communication with said outlet channel (126), such that a cooling fluid intended for cooling the rotor can circulate in the rotor successively through the inlet channel (124), then between the rear flange (19) and the rear side face (144) of the sheet metal pack (14) through said rear connecting channels (195), then inside the sheet metal pack (14) through said longitudinal fluid circulation channels (214), then between the front flange (17) and the front side face (143) through said front connecting channels (175), and finally through the outlet channel (126).

7. Rotor (10) according to claim 6, characterized in that the shaft (12) comprises a hollow front end portion (121) and a solid rear end portion (123) separated from the front end portion (121) by a hollow central portion (122), the front end portion (121) and the central portion (122) being traversed by a cylindrical central cavity, said central cavity forming the inlet channel (124) of the shaft (12), the front end portion (121) also being traversed by at least one peripheral cavity aligned coaxially with the central cavity, said at least one peripheral cavity forming the outlet channel (126) of the shaft (12), and in that at least two holes (125, 127) oriented radially with respect to the axis (X) of the shaft (12) are formed inside the front end portion (121), respectively of the central portion (122), so as to open on one side into the outlet channel (126),respectively the input channel (124), and on the other side in said front link channels (175), respectively said rear link channels (195).

8. Rotor (10) according to claim 7, characterized in that the shaft (12) comprises a main body (120) having a blind hole (128a, 128b) aligned along the axis (X) of the shaft (12), said blind hole (128) comprising two contiguous sections of different internal diameters, namely a first section (128a) having a first internal diameter and a second section (128b) having a second internal diameter, and in that a plastic insert (13) is housed inside the blind hole at the level of the first section (128a), said insert (13) being formed of a tubular portion (131) aligned with the second section (128b) of the blind hole and having an internal diameter that is substantially equal to the second internal diameter, and of an annular portion (132) extending radially around one end of the tubular portion (131),said annular part (132) being positioned at the interface between the first section (128a) and the second section (128b) of the blind hole and having an external diameter which is substantially equal to the first internal diameter, the inlet channel (124) of the shaft (12) being jointly defined by the tubular part (131) of the insert (13) and by the second section (128b) of the blind hole and the corresponding outlet channel (126) of the shaft (12), to the space delimited by the first section (128a) of the blind hole and by the tubular and annular parts (131, 132) of the insert (13).

9. Rotor (10) according to claim 8, characterized in that the insert (13) comprises one or more separating fins (133) extending radially from the outer periphery of the tubular portion (131), each of the separating fins (133) being configured to separate the output channel (126) into two or more segments (126a-126d) of output channels.

10. Rotor (10) according to any one of the preceding claims, characterized in that each of the front and rear flanges (17, 19) has an inner face (173, 193) in contact with a lateral face (143, 144) of the sheet metal pack (14), said inner face (173, 193) being provided with at least two oblong radial grooves (175, 195), each of said radial grooves extending radially from a first end opening onto a central area (172) hollowed out of said flange, at the level of which said radial groove (175, 195) is in fluidic communication with the inlet (124) or outlet (126) channel of the shaft (12), to a second end opening onto one of the longitudinal fluid circulation channels (214).

11. Rotor (10) according to claim 10, characterized in that each of said radial grooves (175, 195) faces a radial hole (125, 127) formed through the shaft (12), said radial hole opening on one side into the inlet channel (124) or outlet channel (126) of the shaft (12) and on the other side into the peripheral wall of the shaft (12).

12. Rotor (10) according to any one of the preceding claims, characterized in that each of the front and rear flanges (17, 19) is provided on its inner face (173, 193) with a circular groove (174) intended to house an annular sealing gasket (16), said sealing gasket (16) being intended to ensure sealing between the flange (17, 19) and the stack of sheets (14).

13. Electric motor (30) comprising a rotor (10) according to any one of the preceding claims.

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