Element for distributing a flow within a hollow shaft

Abstract

The invention relates to a distribution element (30) designed to be mounted within a bore of a shaft so as to form in said bore, optionally in cooperation with a surface of the bore, two fluid circuits, in particular oil circuits, the distribution element (30) comprising a positioning element (39) for positioning the distribution element (30) in the bore, and at least one partition wall (37) for separating the two fluid circuits.

Description

[0001] TITLE: Flow distribution element within a hollow shaft.

[0002] Technical field of the invention

[0003] The invention relates to a flux distribution element within a hollow shaft. The invention also relates to an electric motor rotor shaft comprising such a distribution element. The invention also relates to an electric motor comprising such a shaft or such a distribution element. The invention also relates to a vehicle comprising such an electric motor.

[0004] State of the prior art

[0005] A vehicle, particularly a motor vehicle, generally includes at least one electric traction and / or propulsion motor to move such a vehicle. This is particularly the case for hybrid or electric vehicles.

[0006] Such an electric motor comprises a rotor that rotates near a stator. For example, the rotor has a high, even very high, rotational speed, for example of the order of 16,000 revolutions per minute.

[0007] Such an electric motor heats up during operation, although it should not exceed a certain temperature limit, for example, around 140 degrees Celsius. Indeed, beyond this temperature limit, the magnets of such an electric motor lose, at least partially, their magnetic properties, and this results in malfunctions of the electric motor.

[0008] Furthermore, such a vehicle generally comprises a gearbox for adapting the rotational speed of a ground-contacting element such as a wheel, relative to the rotational speed output by the electric motor. Such an electric motor is generally arranged, at least partially, within such a gearbox. Such a gearbox also reaches a high temperature in operation, for example of the order of 100 degrees Celsius.

[0009] Therefore, preventing such an electric motor from reaching a limit temperature, or even exceeding it, while it is arranged at least partly within such a gearbox which is itself hot, is particularly complex.

[0010] As a result, such an electric motor requires cooling in order to avoid reaching the limit temperature causing malfunctions linked to the loss of the magnetic properties of the magnets.

[0011] Presentation of the invention

[0012] The present invention aims to provide a distribution element remedying the above drawbacks. In particular, the invention makes it possible to obtain an electric motor rotor comprising a shaft which provides cooling of the motor, compatible with the high speed of the rotor and ensuring cooling at each end of the rotor although the admission of a cooling fluid is only at one end of the rotor.

[0013] Summary of the invention

[0014] To achieve this objective, the invention relates to a distribution element intended to be fitted within a bore of a shaft so as to form, possibly in cooperation with a surface of the bore, in this bore two fluid circuits, in particular oil circuits, the distribution element comprising:

[0015] - an element for positioning the distribution element in the bore, and

[0016] - at least one separating wall of the two fluid circuits. The invention also relates to a shaft for an electric motor rotor, in particular a traction and / or propulsion motor of a motor vehicle, the shaft comprising:

[0017] - a central bore centered on the axis of the shaft, the central bore being intended to receive oil at an open end of the central bore,

[0018] - a section of the shaft extending axially over a given length of the shaft and being intended to extend substantially opposite a stator of such an electric motor, the section comprising a first part and a second part on either side of a plane passing through the axis of the shaft, the section comprising a first axial end and a second axial end,

[0019] - a first hole extending from the central bore within the first part of the section and close to the first axial end of the section,

[0020] - a second hole extending from the central bore within the second part of the section and close to the second axial end of the section, the shaft comprising a distribution element as defined previously attached within the central bore so as to supply oil to the first hole and the second hole.

[0021] The distribution element can be shaped so as to create, in the central bore, a first chamber for supplying oil to the first hole and a second chamber for supplying oil to the second hole, the first and second chambers being able to communicate with the open end of the central bore.

[0022] The distribution element may comprise the second oil supply chamber, the second chamber may comprise a discharge orifice arranged opposite the second hole. The second chamber may have a hollow half-cylinder shape extending into the second part of the section, the second chamber may have a half-disc-shaped bottom extending perpendicular to the axis of the shaft.

[0023] The distribution element may comprise a hollow half-cylinder shape which may extend into the first part of the section.

[0024] The positioning element may be in contact with the central bore, in particular the positioning element may have the shape of a hollow cylinder with a diameter equal or substantially equal to the diameter of the central bore so as to be force-fitted and / or to stick within the central bore.

[0025] The dividing wall may extend substantially centered on the plane and a half circular pad may extend radially from the dividing wall into the central bore, within the second part of the section, the half circular pad may be arranged between the first hole and the second hole while being spaced from the first hole and the second hole.

[0026] The positioning element may be a cylindrical part of diameter equal or substantially equal to the diameter of a non-opening end of the bore so as to be force-fitted and / or to be glued at the non-opening end.

[0027] An axial end of the first chamber may be arranged at a defined distance from the first hole, in particular at a defined distance of twice the diameter of the first hole, and an axial end of the second chamber may be arranged at a defined distance from the second hole, in particular at a defined distance of twice the diameter of the second hole. The invention also relates to an electric motor, in particular a traction and / or propulsion motor for a vehicle, the electric motor comprising a rotor shaft as defined above or a distribution element as defined above.

[0028] The invention also relates to a vehicle, in particular a motor vehicle, comprising a gearbox, the vehicle comprising an electric motor as defined previously arranged at least partially within the gearbox.

[0029] Presentation of figures

[0030] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of a first and a second embodiment of a distribution element given without limitation in relation to the attached figures among which:

[0031] Figure 1 is a schematic view of a motor vehicle according to one embodiment of the invention.

[0032] Figure 2 is a sectional view of an electric motor comprising a distribution element according to a first embodiment of the invention. Figure 3 is a front view of the distribution element according to the first embodiment of the invention.

[0033] Figure 4 is a perspective view of the distribution element according to the first embodiment of the invention.

[0034] Figure 5 is a sectional view of an electric motor comprising a distribution element according to a second embodiment of the invention.

[0035] Figure 6 is a perspective view of the distribution element according to the second embodiment of the invention.

[0036] Detailed description The direction in which a vehicle, especially a motor vehicle, moves in a straight line is defined as the longitudinal direction X. By convention, the direction perpendicular to the longitudinal direction, located in a plane parallel to the ground, is called the transverse direction Y. The third direction, perpendicular to the other two, is called the vertical direction Z. Thus, we use a direct XYZ reference frame in which X is the longitudinal direction in the front-rear direction of the vehicle, therefore directed towards the rear, Y is the transverse direction directed towards the right and Z is the vertical direction directed upwards. The forward direction corresponds to the direction in which the vehicle usually moves in the longitudinal direction and is opposite to the rear direction.

[0037] As illustrated in Figure 1, a vehicle, in particular a motor vehicle 1, comprises a gearbox 5. The vehicle comprises an electric motor 2, for example an electric traction and / or propulsion motor of the vehicle. Advantageously, the electric motor 2 is arranged, at least partially, within the gearbox 5.

[0038] More specifically, as illustrated in Figures 2 and 5, the electric motor 2 comprises a shaft 10, a rotor 3 and a stator 4. The shaft 10 comprises an axis A. The shaft 10 is the shaft of the rotor 3. In other words, the shaft 10 and the rotor 3, the rotor 3 being for example fixed on the shaft 10, are intended to rotate around the axis A, or substantially around the axis A, for example at a very high speed, for example of the order of 16,000 revolutions / minute. Preferably, the rotor 3 is arranged opposite the stator 4.

[0039] The shaft 10 comprises a bore 20, preferably a central bore 20, that is to say centered on the axis A of the shaft. The shaft 10 comprises an open end 24 of the central bore 20. The bore is intended to receive a fluid at the open end 24. The shaft 10 of the rotor 3 comprises a distribution element or distributor.

[0040] A first embodiment of the distribution element 30 is illustrated in Figures 2, 3 and 4.

[0041] The distribution element 30 is fitted within the bore 20 of the shaft 10. The distribution element 30 then forms, possibly in cooperation with a surface 25 of the bore, two fluid circuits in this bore. By fluid, we preferably mean oil, for example lubricating and / or cooling oil.

[0042] The fluid inlet or admission is provided at the level of the emerging end 24 of the shaft 10. Advantageously, the bore 20 is formed, machined, from this emerging end 24. A first fluid circuit C1 extends from the inlet to a first hole 21. A second fluid circuit C2 extends from the inlet 24 to a second hole 22. The first circuit C1 and the second circuit C2 are marked at the level of the inlet and at the outlet of each hole by an arrow.

[0043] More specifically, as illustrated in Figure 4 in particular, the distribution element 30 comprises a positioning element 39 for positioning the distribution element 30 in the bore 20. For example, the positioning element 39 is in contact, or substantially in contact, with the central bore 20. Advantageously, the positioning element 39 has the shape of a hollow cylinder with a diameter equal or substantially equal to the diameter of the central bore 20. Thus, it is easy to force-fit and / or glue the positioning element 39 within the central bore 20 of the shaft 10. Preferably, the cylindrical positioning element 39 comprises a shoulder 38 intended to come into abutment against or at the level of the opening end of the shaft 10 or inlet 24. The distribution element 30 further comprises at least one separating wall 37 of a flow C separating into two fluid flows or circuits C1, C2, as illustrated in particular in figure 4.

[0044] The shaft 10 for the rotor 3 of the electric motor 2 further comprises a section 15, or cylindrical portion, of the shaft 10 extending axially over a given length L15 of the shaft 10 illustrated in FIGS. 2 and 5. The section 15 is intended to extend, or extend substantially, opposite the stator 4 of the electric motor 2. More precisely, the section 15 comprises a first part 16 and a second part 17 on either side of a plane P passing through the axis A of the shaft 10. In other words, the section 15 is divided, cut, separated in two, in a fictitiously manner, by the plane P so as to obtain the first part 16 (portion of the shaft 10 extending below the axis line A in FIGS. 2 and 5 and over the axial length L15, the plane P extending perpendicular to this view) and the second part 17 (portion of the shaft 10 extending above the axis line A in figures 2 and 5 and over the axial length L15, the plane P extending perpendicular to this view).

[0045] The section 15 comprises a first axial end 11 and a second axial end 12 illustrated in dotted lines in Figures 2 and 5.

[0046] The shaft 10 comprises the first hole 21. The first hole 21 extends for example radially from the central bore 20, within the first part 16 of the section 15, and close to the first axial end 11 of the section 15. Preferably, as illustrated in Figures 2 and 5, the first hole 21 is circular and / or the axis of the first hole 21 extends perpendicular to the plane P. The first hole 21 extends from the central bore 20 to an external surface 18 of the first part 16 of the section 15. Alternatively, several holes, radial or not, are provided so as to extend from the central bore 20 to the external surface 18 of the first part 16 of the section 15. The shaft 10 comprises the second hole 22. The second hole 22 extends for example radially from the central bore 20, within the second part 17 of the section 15, and close to the second axial end 12 of the section 15.Preferably, as illustrated in Figures 2 and 5, the second hole 22 is circular and / or the axis of the second hole 22 extends perpendicular to the plane P. The second hole 22 extends from the central bore 20 to an external surface 19 of the second part 17 of the section 15. Alternatively, several holes, radial or not, are provided so as to extend from the central bore 20 to the external surface 19 of the second part 17 of the section 15.

[0047] The shaft 10 comprises the distribution element attached, fixed, glued, fitted within the central bore 20. Thus, the fluid admitted at the level of the opening end 24 of the bore 20 communicates with, feeds, the first hole 21 and the second hole 22.

[0048] As illustrated in Figure 2, in the first embodiment, the distribution element 30 is shaped so as to create, in the central bore, a first chamber 31 for supplying the first hole 21 and a second chamber 32 for supplying the second hole 22. The first and second chambers 31, 32 communicate with the opening end 24 of the central bore 20.

[0049] More specifically, in the first embodiment illustrated in Figures 3 and 4, it is the distribution element 30 which creates the second supply chamber 32. The second chamber 32 then has the shape of a hollow half-cylinder 35 extending into the second part 17 of the section 15 of the shaft 10 once the element 30 is arranged in the bore 20. The second chamber 32 then has a bottom 33 in the shape of a half-disc extending perpendicular to the axis A so as to close, plug, or seal the hollow half-cylinder 35. The second chamber 32 comprises a hole or discharge orifice 34 for the fluid, for example circular, arranged opposite or at least partially opposite the second hole 22 once the distribution element 30 is inserted into the bore 20 of the shaft 10.

[0050] The distribution element 30 of the first embodiment comprises a hollow half-cylinder shape 36. The hollow half-cylinder 36 extends into the first portion 16 of the section 15 once the element 30 is arranged in the bore 20.

[0051] Preferably, the hollow half-cylinder 35 closed by the bottom 33 and the hollow half-cylinder 36 form a cylinder having a skin or external surface of diameter substantially equal to, preferably slightly smaller than, the diameter of the bore 20. In this case, the external surface of the two half-cylinders 35, 36 form the positioning element 39 facilitating the fixing of the distribution element 30 within the bore 20. The separating wall 37 extends on either side of the fictitious plane P separating the first part 16 from the second part 17 of the section 15, preferably being centered relative to the plane P. The separating wall 37 extends in the direction of the inlet 24 so as to divide the flow of fluid C arriving at the inlet into two flows C1, C2. Advantageously, as illustrated in FIG. 2, the separating wall 37 does not extend to the level of the shoulder 38.Indeed, the separating wall 37 stops at a distance L24 from the inlet 24, that is to say from the orifice of the bore 20 or from the shoulder 38. Thus, the flow C arriving at the inlet 24 is not divided upon entering the distribution element 30 but after having traveled the distance L24 within the distribution element 30. For example, the distance L24 is equal to at least the internal diameter of the tubular part of the element 30 receiving the fluid, or even twice this internal diameter, so as to obtain a laminar flow instead of a turbulent one. Advantageously, as illustrated in Figure 2, the axial end of the first chamber 31 corresponds to the non-opening end 23 of the bore 20. Preferably, the end 23 is arranged at a defined distance D from the first hole 21. For example, the defined distance D is twice the diameter of the first hole 21, or at least twice the diameter of the first hole 21.

[0052] Advantageously, as illustrated in Figure 2, the axial end of the second chamber 32 is obtained by the bottom 33. The bottom 33 is preferably arranged at a defined distance D from the second hole 22. For example, the defined distance D is twice the diameter of the second hole 22, or at least twice the diameter of the second hole 22. The bottom 33 is arranged, in the axial direction, after the second hole 22, that is to say between the non-opening end 23 and the second hole 22 so as to allow the fluid in the second chamber 32 to access the second hole 22.

[0053] In this first embodiment, the distribution element is therefore a part comprising a cylindrical portion which allows the oil to be distributed uniformly over its internal surface by centrifugation at the inlet 24. On the side of the first part 16 of the section 15, the element 30 extends in the axial direction with the open semi-cylindrical part 36 which allows the oil to pass towards the bottom 23 of the central bore 20 of the rotor shaft. On the side of the second part 17 of the section 15, the element 30 extends in the axial direction with the semi-cylindrical chamber 32 comprising the orifice 34 for radial oil discharge arranged opposite the second hole 22 made in the rotor shaft on the oil inlet side.

[0054] It should be noted that the shoulder 38 makes it possible to ensure axial positioning of the distribution element 30 relative to the central bore 20. Preferably, the contact between the shoulder 38 of the element 30 and one end or one shoulder of the central bore 20 of the shaft 10 makes it possible to ensure that the orifice 34 of the hollow half-cylinder 35 is at the level, along the axis A, of the second hole 22 formed in the shaft.

[0055] According to a second embodiment illustrated in Figures 5 and 6, the distribution element 40 is also shaped so as to create, in the central bore, a first chamber 41 for supplying the first hole 21 and a second chamber 42 for supplying the second hole 22. The first and second chambers each communicate with the opening end 24 of the central bore 20.

[0056] In this second embodiment, the distribution element 40 comprises a positioning element 49 for positioning the distribution element 40 in the bore 20. For example, the positioning element 49 is a cylindrical part of diameter equal, or substantially equal, to the diameter of the non-emerging end 23 of the bore 20. Thus, the distribution element 40 can be force-fitted and / or be glued at the non-emerging end 23. In addition, the distribution element 40 comprises at least one separating wall 47 of the two fluid circuits.

[0057] More precisely, the separating wall 47 preferably extends substantially centered on the fictitious plane P separating the first part 16 from the second part 17 of the section 15. Preferably, the separating wall 47, for example of the plate type, comes into contact, or substantially in contact, with the wall 25 of the bore 20. In the case of a positioning element 49 of cylindrical shape in the bore, preferably the separating wall has a clearance relative to the bore 20 so as not to hinder the assembly of the positioning element at the bottom 23 of the bore 20. For example, the separating wall 47 comprises two edges 46 intended to come into contact, or substantially in contact, with the bore 20. For example, the section perpendicular to the axis A of each edge 46 is curved so as to follow the circular section of the central bore 20 opposite each edge.The curvature of each edge 46 then has an axis radius A of length just less than the radius of the bore 20 at this level.

[0058] The distribution element 40 further comprises a half circular pellet 48. The half pellet or the half circular plate 48 extends radially from the separation wall 47. Thus, the half pellet 48 extends to the central bore 20, or substantially to the bore 20 so as not to hinder the assembly of the element 40 within the bore 20. The half pellet 48 extends into the second part 17 of the section 15. The half pellet 48 therefore creates an axial bottom, or substantially an axial bottom, for the second chamber 42.

[0059] Thanks to the separating wall 47, in particular centered on the plane P, and the half-pad 48, the distribution element 40 creates in the bore 20 the first chamber 41 within the first part 16 of the section 15 of the shaft 10 and the second chamber 42 within the second part 17 of the section 15 of the shaft 10.

[0060] More precisely, the first chamber 41 has a substantially half-cylinder shape extending from the disc or cylinder type positioning element 49 to one end 45 of the separation wall 47 on the intake side. The wall or surface 25 of the bore 20 on the side of the first part 16 of the section helps to create the first chamber 41.

[0061] The second chamber 42 also has a substantially half-cylinder shape extending from the half-pad 48 to the end 45 of the separation wall 47 on the intake side. The wall or surface 25 of the bore 20 on the side of the second part 17 of the section helps to create the second chamber 42. Advantageously, as illustrated in FIG. 5, the separation wall 47 does not extend to the emerging end 24 of the shaft 10. Indeed, the separation wall 47 stops at the distance L24 relative to the intake 24, that is to say relative to the orifice of the bore 20. Thus, the flow C arriving at the intake 24 is not divided upon arriving in the bore

[0062] 20 but after having traveled the distance L24 in the central bore 20. For example, the distance L24 is equal to at least the diameter of the bore 20, or even twice this diameter, so as to obtain a laminar flow instead of turbulent.

[0063] Note that the half circular pad 48 is arranged, positioned, in the direction of the axis A, between the first hole 21 and the second hole 22. In addition, the half circular pad 48 is axially distant from the first hole

[0064] 21 and the second hole 22.

[0065] Advantageously, as illustrated in Figure 5, the axial end of the first chamber 41, for example created by the positioning element 49, is arranged at a defined distance D from the first hole 21. For example, the defined distance D is twice the diameter of the first hole 21, or at least twice the diameter of the first hole 21.

[0066] Advantageously, as illustrated in Figure 5, the axial end of the second chamber 42, created by the half-pastille 48, is arranged at a defined distance D from the second hole 22. For example, the defined distance D is twice the diameter of the second hole 22, or at least twice the diameter of the second hole 22. The half-pastille 48 is arranged behind the second hole 22 in the direction of the non-opening end 23 of the bore.

[0067] It should be noted that the positioning element 49 makes it possible to ensure axial positioning of the distribution element 40 relative to the central bore 20. Preferably, the contact between the element 49 of the element 40 and the bottom of the end 23 of the central bore 20 of the shaft 10 makes it possible to ensure axial positioning, i.e. along the axis A, of the distribution element 40 within the bore 20.

[0068] Alternatively, according to a non-illustrated variant of the second embodiment, the separating wall comprises two edges coming into contact with the central bore of the shaft and ensures positioning with respect to the bore so that the distribution element can be without a cylindrical pellet-type positioning element. In this case, the end 23 of the bore comes into contact with the separating wall which ensures the bottom of the first chamber.

[0069] Alternatively, according to a non-illustrated variant of the second embodiment, the distribution element is devoid of half-pad 48. For example, the distribution element only comprises a separation plate 47 capable of being positioned centered on the plane P and coming into contact with the end 23 of the bore 20.

[0070] For example, the seal for the oil flow C on the intake side 24 between a fixed casing and the rotating shaft end 20 is obtained via radial grooves provided on the shaft and a smooth surface of a bore in the casing. In this case, the fluid, preferably oil, creates fluid "seals" in the grooves like O-rings. This eliminates the need for lip seals which generate friction and reduce the efficiency of the electric motor.

[0071] For example, the flow distribution element 30; 40 is made of plastic, such a material being resistant, for example, up to 200 degrees C. Alternatively, the distribution element is made of metal, for example by sintering. As illustrated in Figures 2 and 5, the oil flow C, preferably coming from a pump, in particular a pump dedicated to the lubrication of the gearbox if necessary, is admitted at the inlet 24, that is to say at the open end of the shaft 10. As a reminder, preferably the oil flow C comes from a fixed casing and passes at the inlet 24 into the shaft 20 which rotates, in particular at high speed. As mentioned previously, the oil flow first travels a distance L24 (either within a tubular part of the distribution element 30 of the first embodiment, or directly within the bore 20 in the second embodiment).The distance L24 makes it possible to attenuate any turbulence in the flow of oil linked to the passage from a fixed part, the casing, to a rotating part, the shaft 10. Thus, at the end of this distance L24, the oil flows, or flows substantially in laminar flow, at least in a turbulent or non-turbulent manner. Thus, the separating wall 37; 47 is placed at this level so as to divide the oil flow C into two flows C1, C2. The flow C1 joins the first chamber 31; 41 and the flow C2 joins the second chamber 32; 42. In the case of a dividing wall dividing the section S20 of the bore (second embodiment - figure 5) or the section at the shoulder 38 (first embodiment - figure 2) into two straight sections S1, S2 of equal area, each substantially in the shape of a half disc, the oil flow C is substantially divided into two equally.Thus, once the oil flow is continuous, in the case of the areas of the holes 21, 22 being identical or substantially identical, the flow C1 leaving the first hole 21 and the flow C2 leaving the second hole 22 are identical or substantially identical.

[0072] The distance D between the bottom of the first chamber and the first hole and between the bottom of the second chamber and the second hole makes it possible to attenuate, or even eliminate, the turbulence in the flow of oil generated by the presence of these cavity bottoms. Alternatively, one hole may have a section greater than the section of the other hole, for example if more cooling is required on one side of the rotor and / or stator. Alternatively, or in addition, if it is desired to increase the oil flow on one side, the section of the distribution element may make it possible to make the sections of the first and second chambers unequal. In other words, the geometry of the distribution element may be adapted, modified, to calibrate each flow C1, C2, for example 70 percent at the bottom (flow C1) and 30 percent at the inlet (flow C2), or vice versa.Alternatively, or in addition, several first holes (radial or not) are arranged in the first part 16 of the section 15 from the bore 20 and / or several second holes (radial or not) are arranged in the second part 17 of the section 15 from the bore 20. In this case, for the first embodiment, as many corresponding orifices 34 are provided in the second chamber 32 so as to be opposite the second holes.

[0073] Regardless of the embodiment, an angular positioning means (not shown) is provided within the central bore and / or on the distribution element so as to angularly orient, around the axis A, the distribution element relative to the bore. This prevents any subsequent angular offset between the distribution element and the central bore.

[0074] For example, an axial groove is provided within the bore and a projection, possibly of the lug type, extends radially outwardly from the distribution element. In the first embodiment, for example, one of the hollow half-cylinders 35, 36 comprises the projection. In the second embodiment, for example, the positioning element 49 comprises the angular positioning projection, and / or at least one edge 46 of the partition wall 47 comprises the positioning projection, and / or the circular half-pad 48 comprises the positioning projection. Indeed, it is appropriate to arrange each hole provided in the shaft with the corresponding chamber, possibly with an orifice of a corresponding chamber provided in the distribution element.Alternatively or additionally, a position-holding means, for example welding and / or press-fitting and / or glue, is provided to angularly hold the distribution element within the bore. Thus, the position-holding means can act as an angular positioning means, which simplifies the manufacture of the shaft and / or the distribution element.

[0075] Thanks to the solution, the oil flows through the holes 21, 22 and is consequently projected on each side of the rotor 3 and the stator 4 by centrifugal force. The diffusion of this oil on either side of the rotor, and / or stacks of the rotor, and / or the stator, contributes to effectively cooling the electric motor 2. As a reminder, the rotor can rotate at a speed of the order of 16,000 revolutions per minute.

[0076] Thanks to this solution, the electric motor does not reach the temperature limit of around 140 degrees C. Thus, the magnets retain their magnetic properties, are not altered, and the motor operates perfectly. In addition, it is avoided that only one of the two sides is properly cooled. As mentioned previously, the solution preferably aims to create two equal flows on either side of the rotor / stator assembly so as to cool both sides equally. This prevents one side from being less cooled and the magnets arranged at this level from creating malfunctions in the electric motor.

[0077] The solution is compatible for an electric motor integrated within a gearbox. Indeed, although the gearbox has a temperature of the order of 100 degrees C for example, cooling via the holes makes it possible to maintain each side face of the electric motor below the critical temperature, for example of the order of 140 degrees C. In summary, the solution consists of placing a physical element in the center of the rotor shaft to separate the flow of oil arriving in the shaft, and its centrifugation into two distinct flows. As seen previously, preferably, a single hole, for example radial, is provided in the rotor shaft through which a first half of the flow is directed towards the outside of the shaft, and one or more holes at the other end of the shaft to direct the second half of the oil flow to the other side of the rotor.

[0078] In other words, the invention relates to a separator of the oil flow into two flows for cooling an electric motor. Although the oil inlet is arranged on one side of the shaft, the oil diffusion hole closest to the inlet does not offer a higher flow rate than the hole furthest from the inlet. Furthermore, the solution makes it possible to obtain oil flow rates through the holes independent of the rotational speed.

[0079] The solution therefore makes it possible to cool the electric motor with oil injected into the bore 20 of the shaft 10 of the rotor 3. Although the oil is introduced into the inlet 24 at the bore 20, i.e. at the center of the rotor, the oil is projected by centrifugation towards the inside of the stator 4 which makes it possible to take calories from the hot parts, in particular the rotor and the stator. Thus, the solution is suitable for cooling the heat flow produced by the symmetrical losses of the electric motor.

[0080] The solution allows, if desired, a distribution of the oil flow arriving in the bore into two equal flows so as to optimize cooling over the entire engine speed range.

[0081] Eventually, the solution allows to increase, if necessary, the diameters of the holes 21, 22 since their diameter has little or no influence on the distribution of the oil. Drilling or machining holes of larger diameter is advantageous because it is easier and therefore less expensive, which contributes to saving money.

[0082] Although two embodiments have been described, other forms of the flow distribution element or separator may be suitable for creating two separate chambers within the central bore such that each chamber supplies oil to at least one hole provided on the inlet side and at least one other hole provided at the other end of the shaft.

[0083] The solution is suitable for cooling any electric motor equipped with an oil intake. The solution is particularly suitable for cooling an electric motor arranged, at least in part, within a gearbox, particularly in a vehicle. Indeed, although the gearbox reaches a temperature of around 100 degrees C for example, the cooling resulting from the solution makes it possible to cool the electric motor, the rotation of which can be very high, so as to prevent the electric motor from reaching a critical temperature of around 140 degrees C. As a reminder, such a temperature causes losses of magnetic properties of the magnets, which generates malfunctions of the electric motor.

[0084] The solution therefore provides efficient cooling for the electric motor, compatible with its installation within a gearbox. In addition, the distribution element is easy to manufacture and integrate into the shaft in which a bore has been machined, for example. Thus, the solution makes it possible to obtain an electric motor rotor that provides cooling at each end of the rotor, for example with two equal or even equal oil flows.

[0085] As a remark, the solution therefore achieves the desired objective of obtaining an electric motor rotor comprising a shaft which provides cooling of the motor, compatible with the high speed of the rotor and ensuring cooling at each end of the rotor although the intake of the cooling fluid is only at one end of the rotor, and has the advantage of being able to be adapted to all types of electric motors benefiting from an intake of fluid for its lubrication and / or its cooling.

Claims

CLAIMS 1. Distribution element (30; 40) intended to be fitted within a bore (20) of a shaft (10) so as to form, possibly in cooperation with a surface of the bore, in this bore two fluid circuits, in particular oil circuits, the distribution element (30; 40) comprising: - a positioning element (39; 49) of the distribution element (30; 40) in the bore (20), and - at least one separating wall (37; 47) of the two fluid circuits.

2. Shaft (10) for a rotor (3) of an electric motor (2), in particular of a traction and / or propulsion motor of a motor vehicle (1), the shaft (10) comprising: - a central bore (20) centered on the axis (A) of the shaft (10), the central bore (20) being intended to receive oil at an open end (24) of the central bore (20), - a section (15) of the shaft (10) extending axially over a given length (L15) of the shaft (10) and being intended to extend substantially opposite a stator (4) of such an electric motor (2), the section (15) comprising a first part (16) and a second part (17) on either side of a plane (P) passing through the axis (A) of the shaft (10), the section (15) comprising a first axial end (11) and a second axial end (12), - a first hole (21) extending from the central bore (20) within the first part (16) of the section (15) and close to the first axial end (11) of the section (15), - a second hole (22) extending from the central bore (20) within the second part (17) of the section (15) and close to the second axial end (12) of the section (15), the shaft (10) comprising a distribution element (30; 40) according to the claim 1 reported within the central bore (20) so as to supply oil to the first hole (21) and the second hole (22).

3. Shaft (10) according to the preceding claim, characterized in that the distribution element (30; 40) is shaped so as to create, in the central bore, a first chamber (31; 41) for supplying oil to the first hole (21) and a second chamber (32; 42) for supplying oil to the second hole (22), the first and second chambers being in communication with the open end (24) of the central bore (20).

4. Shaft (10) according to the preceding claim, characterized in that the distribution element (30) comprises the second oil supply chamber (32), the second chamber (32) comprising an evacuation orifice (34) arranged opposite the second hole (22).

5. Shaft (10) according to the preceding claim, characterized in that the second chamber (32) has the shape of a hollow half-cylinder (35) extending into the second part (17) of the section (15), the second chamber (32) having a bottom (33) in the shape of a half-disc extending perpendicular to the axis (A) of the shaft (10).

6. Shaft (10) according to claims 4 and 5, characterized in that the distribution element (30) comprises a hollow half-cylinder shape (36) extending into the first part (16) of the section (15).

7. Shaft (10) according to one of claims 2 to 6, characterized in that the positioning element (39) is in contact with the central bore (20), in particular the positioning element (39) has the shape of a hollow cylinder with a diameter equal or substantially equal to the diameter of the central bore (20) so as to be force-fitted and / or to stick within the central bore (20).

8. Shaft (10) according to one of claims 2 or 3, characterized in that the separating wall (47) extends substantially centered on the plane (P) and in that a half circular pellet (48) extends radially from the separating wall (47) in the central bore (20), within the second part (17) of the section (15), the half circular pellet (48) being arranged between the first hole (21) and the second hole (22) while being distant from the first hole (21) and the second hole (22).

9. Shaft (10) according to the preceding claim, characterized in that the positioning element (49) is a cylindrical part of diameter equal or substantially equal to the diameter of a non-emerging end (23) of the bore (20) so as to be force-fitted and / or to be stuck at the non-emerging end (23).

10. Shaft (10) according to one of claims 2, or 4 to 9, in combination with claim 3, characterized in that an axial end of the first chamber (31; 41) is arranged at a defined distance (D) from the first hole (21), in particular at a defined distance (D) of twice the diameter of the first hole (21), and in that an axial end of the second chamber (32; 42) is arranged at a defined distance (D) from the second hole (22), in particular at a defined distance (D) of twice the diameter of the second hole (22).

11. Electric motor (2), in particular traction and / or propulsion motor for a vehicle, characterized in that the electric motor (2) comprises a rotor shaft (10) according to one of claims 2 to 10 or a distribution element (30; 40) according to claim 1.

12. Vehicle, in particular a motor vehicle (1), comprising a gearbox (5), characterized in that the vehicle comprises an electric motor (2) according to the preceding claim arranged at least partially within the gearbox (5).

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