Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/32—Rotating parts of the magnetic circuit with channels or ducts for flow of cooling medium
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/28—Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures
  • H02K1/30—Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures using intermediate parts, e.g. spiders
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
  • H02K7/003—Couplings; Details of shafts

Definitions

• 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.
• current electric motors have a rotor attached to a shaft and a stator which surrounds the rotor.
• the stator is mounted in a casing which has bearings for the rotational mounting of the shaft.
• the rotor comprises a body formed by a stack of laminations or pole wheels (claw pole) held in the form of a package by means of a suitable fastening system.
• the rotor body has internal cavities housing permanent magnets.
• the stator comprises a body consisting of a stack of laminations forming a crown, the inner face of which is provided with teeth delimiting two by two a plurality of slots open towards the inside of the stator body and intended to receive phase windings.
• phase windings pass through the notches of the stator body and form buns protruding from either side of the stator body.
• the phase windings can for example consist of a plurality of U-shaped conductor segments, the free ends of two adjacent segments being connected together by welding.
• 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 stack of sheets, said screws being secured to the flanges by means of nuts.
• the front and rear flanges are generally formed of a non-magnetic, heat-conducting material, for example a metal.
• the crankcase generally 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 the rotational mounting of the rotor shaft.
• the invention therefore aims to provide 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 above.
• the invention relates to a rotor for an electric motor comprising:
• 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 between them, said second internal cavities passing through axially the entire stack of sheets such that they open out, at one of their ends, at a front side face of said stack of sheets and, at another of their ends, at a rear side 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;
• a front flange and a rear flange mounted coaxially on the rotor shaft and arranged axially on either side of the stack of sheets so as to be contiguous respectively to the front and rear side faces of the stack of sheets;
• the shaft is provided with at least a first internal channel for the circulation of a cooling fluid, said inlet channel, and with at least a second internal channel for the circulation of a cooling fluid, said channel outlet, and in that the front flange, respectively the rear flange, is configured to form with the front side face, respectively the rear side face, of the stack of laminations at least two front connection channels, respectively at least two rear link, inside which a cooling fluid can circulate, each of said front link channels, respectively rear, being in fluid communication with one of said inlet and outlet channels and with one of said second internal cavities;
• the rotor further comprises at least two filler modules of plastic material, each of said filler modules being intended to be housed in one of said second internal cavities and being configured so as to form, in combination with
• 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 stack of sheets.
• These longitudinal channels having a smaller volume than that of the second internal cavities, the cooling fluid will circulate optimally inside the stack of sheets.
• the filling modules it will thus be possible to position the longitudinal channels close to the permanent magnets of the rotor, thus causing the cooling fluid to circulate as close as possible to the hot regions of the stack of laminations. A better heat dissipation will thus be obtained.
• the fact of circulating the cooling fluid through the end plates generates few modifications at the level of the general structure of the electric motor and, therefore, offers a relatively inexpensive solution to the problem of evacuation. heat in electric motors.
• 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 packet of sheet which at least partially defines one of the second internal cavities.
• each longitudinal fluid circulation channel has a serpentine shape.
• said front connection channels are in fluid communication with said inlet channel and said rear connection 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 pack of laminations through the said front connection channels, then inside the pack of laminations through the said longitudinal fluid circulation channels , then between the rear flange and the rear side face of the stack of sheets through said rear connection channels, and finally through the outlet channel.
• 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 traversed 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 with respect to the axis of the shaft are formed at 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 channels front link, respectively said rear link channels.
• said rear connection channels are in fluid communication with said inlet channel and said front connection 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 side face of the pack of laminations through the said rear connecting channels, then inside the pack of laminations through the said longitudinal fluid circulation channels , then between the front flange and the front side face through said front connecting channels, and finally through the outlet channel.
• 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 traversed 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 from the shaft, and at least two holes oriented radially with respect to the axis of the shaft are formed inside the front end portion, respectively the central portion, so as to emerge from a side in the output channel, respectively the input channel, and on the other side in the said front link channels, respectively the said rear link channels.
• 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 part aligned with the second section of the blind hole and having an internal diameter which is substantially equal to the second internal diameter, and an annular portion extending radially around one of the ends of the tubular part, said annular part being positioned at the level of 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 inlet channel of the shaft being defined jointly by the tubular part of the insert and by the second section of the blind hole and the outlet 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.
• the insert comprises one or more splitter fins extending radially from the outer periphery of the tubular part, each of the splitter fins being configured to separate the outlet channel into two or more outlet channel segments.
• each of the front and rear flanges has an internal face in contact with a lateral face of the stack of laminations, said internal face being provided with at least two radial grooves of oblong shape, each of said radial grooves extending radially from a first end opening onto a hollow central zone of said flange, at the level of which said radial groove is in fluid communication with the inlet or outlet channel of the shaft, up to a second end opening onto one of the longitudinal circulation channels of fluid.
• 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 tree.
• each of the front and rear flanges is provided on its internal face with a circular groove intended to accommodate an annular-shaped seal, said seal being intended to provide sealing between the flange and the stack of sheets .
• the invention also relates to an electric motor comprising a rotor as defined above.
• Figure 1 is a truncated perspective view of a rotor-stator assembly according to a first embodiment of the invention.
• Figure 2 is a longitudinal sectional view of the rotor-stator assembly shown in Figure 1.
• Figure 3 is a longitudinal sectional view of an electric motor incorporating the rotor and stator of Figure 1.
• Figure 4 is a perspective view of the laminations of the rotor of figure 1, equipped with permanent magnets.
• Figure 5 is a perspective view of the filling modules of the rotor of Figure 1.
• Figure 6 is a perspective view of the stack of sheets of Figure 4 equipped with the filling modules of Figure 5 and permanent magnets.
• Figure 7 is a perspective view of the shaft fitted to the rotor of figure 1.
• Figure 8 is a longitudinal sectional view of the shaft of figure 7.
• Figure 9 is a front axial view of the shaft of Figure 7.
• Figure 10 is a perspective view of the insert used in the shaft of Figure 7.
• Figure 11 is a perspective view of the outer face of the front flange used in the rotor of Figure 1.
• Figure 12 is a perspective view of the internal face of the flange of figure 11.
• Figure 13 is a longitudinal sectional view of a shaft fitted to a rotor according to a second embodiment of the invention.
• an axial orientation relates to an orientation parallel to the axis of rotation of the rotor and a radial orientation relates to an orientation perpendicular to the axis of rotation of the rotor.
• forward and aft refer to separate positions along the axis of rotation of the rotor.
• the "front" end of the rotor shaft corresponds to the end of the shaft on which can be fixed a pulley, a pinion, a spline intended to transmit the rotational movement of the rotor to any other similar motion transmission device.
• Figures 1 and 2 show 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 stack of laminations 14 (shown in FIG. 4) made of a ferromagnetic material, in particular steel, said body being integral in rotation with a shaft 12 mounted rotatably 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 stack of laminations 14 (see FIG. 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.
• the magnets 15 have the shape of a parallelepiped 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 side face 143 and a side face rear 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 star pattern with several branches.
• Sheet pack 14 is mounted coaxially on the shaft 12.
• the shaft 12 can be force-fitted inside a central opening of the stack of laminations 14 so as to connect the body of the rotor in rotation with the shaft 12.
• the stack of laminations 14 is formed by an axial stack of laminations which extend in a radial plane perpendicular to the axis X of the shaft 12.
• a plurality of fixing holes 11 are made in the stack of laminations 14 to allow the passage of fixing screws (not shown). These fixing holes 11 are through so that it is possible to pass a screw inside each hole 11.
• a first end of the screws bears against the outer face of a front end flange 17, while the other end of the screws protrudes from the outer face of a rear end flange 19 and is threaded so as to receive a nut which, once screwed, exerts pressure against said outer face.
• the stack of sheets 14 is clamped axially between the front end flange 17 and the rear end flange 19.
• These flanges 17, 19 can advantageously make it possible to ensure balancing of the rotor 10 while allowing good maintenance of the magnets 15 inside the first internal cavities 141 .
• These flanges can be balanced 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.
• an electric motor 30 equipped with the rotor 10 of Figure 1.
• This electric motor 30 notably comprises a casing in two parts housing the rotor 10 and an annular stator 36 which surrounds the rotor 10 coaxially with the shaft 12.
• the casing notably comprises a front bearing 32 and a rear bearing 34 connected to the one to the 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.
• Buns 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.
• the stack of laminations 14 of the rotor 10 also comprises a plurality of second internal cavities 142 extending in a radial direction with respect to the axis X and are axially traversing.
• These second internal cavities 142 are configured to house filling modules 21 (as represented for example in FIG. 5) made of plastic material, each filling module 21 being configured to form, in combination with an internal wall of the sheet metal package 14 which defines one of the second internal cavities 142, at least one longitudinal fluid circulation channel.
• 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 ring portion shape and are evenly distributed around the X axis. Two directly adjacent cavities 142a- 142d are separated by a radial segment 18 of the stack of laminations 14 so that a central annular portion of the rotor body is formed an alternation of second internal cavities 142a-142d and radial segments 18.
• each cavity 142a-142d opens out, at one of its ends, at the level of the front side face sheets 14, and, at another of its ends, at the level of the rear side face 144 of said stack of sheets 14.
• Each of the front and rear side faces 143, 144 faces and is directly adjacent to an internal face 173, 193 of the front and rear flanges 17, 19 respectively.
• each filling module 21 has a shape substantially complementary to one of the second internal cavities 142 so as to fill it almost entirely.
• Each filling module 21 thus has a semi-cylindrical shape defined in particular by a front wall 21 1 and a rear wall 213 connected by a curved longitudinal wall 212 which adjoins a corresponding internal wall of the stack of sheets 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 level of the front wall 211 to a rear end 216 located at the level of the rear wall 213.
• These longitudinal grooves 214 are intended to form, in combination with the internal walls of the sheet metal packet 14 adjoining the filling modules 21, longitudinal fluid circulation channels opening, at their front end 215, on fluid circulation channels 175 (shown for example in FIG. 3) formed at least partially inside the front end flange 17, and, at their rear end 216, on fluid circulation channels 195 formed at least partially inside the rear end flange 19.
• these longitudinal fluid circulation channels 214 will make it possible to circulate a cooling fluid inside the rotor 10, being in contact with a portion of the stack of laminations 14 which is relatively close to the magnets 15. This will therefore result in better heat removal and improved operation of the rotor 10.
• An advantageous solution consists for example, as in the specific embodiment represented in FIG. 5, of configuring each longitudinal groove 214 so that it describes a serpentine shape.
• This shaft 12 comprises in particular a main body 120 formed of a front end portion 121 and a portion of rear end 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 level of the first section 128a.
• this insert 13 is formed of a tubular part 131, having an internal diameter Di substantially equal to the internal diameter D2, and 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 outer periphery of the tubular part 131, said fins 133 being perpendicular in pairs. Each of the fins 133 has a length such that its free end is tangent to the outer peripheral edge of the annular part 132.
• the shaft 12 has a first channel 124, called the inlet channel, by which can convey a cooling fluid intended to cool the rotor 10, 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 from the lamination stack 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 inner 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.
• 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 out, on one side, into one of the segments 126a-126d of the outlet channel 126 and, on the other side, in a central zone 172 of the front flange 17 which communicates with the front connection channels 175, as represented in FIG. 3.
• 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 emerge, on one side, in the inlet channel 124 and, on the other side, in a central zone 192 of the rear flange 19 which communicates with the channels rear link 195.
• the front and rear link channels 175, 195 are formed respectively inside the front and rear flanges 17, 19.
• FIGs 11 and 12 there is shown the front flange 17 fitted to the rotor 10 of Figure 1.
• 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 outer face 171 and an inner face 173.
• the inner face 173 is in contact with the front side 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 grooves 175 of oblong shape extending radially from a central zone 172 hollowed out of said flange to an intermediate zone of said flange, the eight grooves 175 being offset by an angle of 45 ° to each other.
• the outer face 171 therefore has several protrusions 178 matching the hollow shape of the underlying grooves 175.
• Cylindrical cross-section cavities 176 are also provided at the outer 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 of this fact formed through the front flange 17 to allow the passage of the threaded rod of said screw.
• 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 seal 16 of annular shape, said seal 16 being intended to ensure sealing between the front or rear flange 17, 19 and the stack of sheets 14.
• the circular groove 174 will be radially farther from the central zone 172 than the distal ends 175a of the grooves 175.
• each of the grooves 175 has a distal end 175a and a proximal end 175b.
• the proximal end 175b opens onto the central zone 172 towards which the ends 125a of the radial holes 125 of the shaft 12 also open and the distal end 175a faces the front end 215 of one of the longitudinal channels 214 of one of the filling modules 21.
• fluid communication takes place between the radial holes 125 of the shaft 12 and the longitudinal channels 214 via , successively, of the central zone 172 and the radial grooves 175 of the front flange 17.
• fluid communication takes place between the radial holes 127 of the shaft 12 and the longitudinal channels 214 via, successively, of the central zone 192 and of 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.
• 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 flange rear 19 and the rear side face 144 of the stack of sheets 14 through the rear connection channels 195, then inside the stack of sheets 14 through the longitudinal channels 214, then between the front flange 17 and the front side face 143 of the stack of sheets 14 through the front connecting channels 175, and finally through the segments 126a-126d of the output channel 126 of the shaft 12.
• a cooling fluid such as oil for example
• FIG. 13 there is shown a variant embodiment of a shaft 12 that 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 on the 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 rear end 124b closed.
• Near the rear end 124b is formed a series of four holes 125 oriented radially relative 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 level of 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.
• the rear end portion 123 is traversed by a central cavity 126 of cylindrical shape, said cavity having a rear end 126a open to the outside and a front end 126b closed.
• the rear end portion 123 is thus configured to allow the entry of a flow of cooling fluid at the level of 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.
• the central cavity 124 will thus be called the cooling fluid inlet channel and the central cavity 126 will be called the cooling fluid outlet channel.
• the cooling fluid will be able to circulate in the rotor 10 successively through the inlet channel 124 of the shaft 12, then between the front flange 17 and the front side face 143 of the stack of laminations 14 at the through the front connection channels 175, then inside the laminations package 14 through the longitudinal channels 214 for fluid circulation, then between the rear flange 19 and the rear side face 144 of the laminations package 14 through the channels rear link 195, and finally through the outlet channel 126 of the shaft 12.
• the invention is obviously not limited to the embodiments as described above.
• the number of second internal cavities 142, and of radial holes 125, 127 may differ from four, and the number of front and rear connection channels 175 , 195 may differ from eight.
• 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.
• the rotor may comprise three (or another odd number) second internal cavities 142, said second internal cavities 142 being distributed in a regular manner around the axis X so as not to create unbalance for the rotor.
• the respective centers of gravity of the second internal cavities 142 may form an equilateral triangle in a plane perpendicular to the axis X and the center of gravity of this equilateral triangle will be aligned with the axis X.
• the rotor 10 of FIG. 1 could include an insert 13 without separating fins 133.
• 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.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Iron Core Of Rotating Electric Machines (AREA)

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• 2022
  • 2022-02-18 FR FR2201476A patent/FR3132993B1/fr active Active
• 2023
  • 2023-02-15 EP EP23708844.8A patent/EP4480068A1/de active Pending
  • 2023-02-15 WO PCT/FR2023/050204 patent/WO2023156735A1/fr not_active Ceased

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