Electrical equipment with improved thermal tolerance, and associated vehicle

Abstract

Electrical equipment with improved thermal tolerance, and associated vehicle. An electrical equipment (20) comprises: - a protective housing (30) including a circumferential lateral wall (46) made of a first material and two end flanges (48), the housing (30) delimiting an internal space (32) defined around a central axis (A), and - a stator (34) made of at least a second material, disposed in the internal space (32) around the axis (A). The stator (34) includes a plurality of mounting conduits (58) extending parallel to the axis (A) and opening on either side of the stator (34). The equipment (20) includes a plurality of bars (44) extending within the conduits (58) and having ends (64) fixed to the flanges (48). The circumferential wall (46) has at least one slot (51) extending through the entire thickness of the circumferential wall (46) and from one flange (48) to the other. Figure for the abbreviation: 2

Description

Title of the invention: Electrical equipment with improved thermal tolerance, and associated vehicle

[0001] The present invention relates to electrical equipment, in particular for a vehicle, comprising:

[0002] - a protective housing comprising a lateral circumferential wall made of a first material and two end plates, the housing delimiting a substantially cylindrical internal space defined around a central axis,

[0003] - a stator made of at least one second material, arranged in the internal space around the axis.

[0004] The invention also relates to a vehicle comprising the preceding electrical equipment.

[0005] Rotating electrical equipment, such as electric motors or alternators, generally comprises a fixed stator and a rotor mounted on a rotating shaft, arranged in a protective housing also called a casing.

[0006] The stator consists of an assembly of magnetic metal sheets, in particular made of ferrous metals, for example steel. The protective casing is generally made of cast iron, which is an advantageous material in terms of durability and production cost.

[0007] In some cases, in order to improve heat dissipation in the internal space of the housing, as well as to reduce the mass of the equipment, it is desirable to make a part of the housing, for example the circumferential part, from lighter and better thermally conductive metals, for example from aluminum alloy. Reducing the total mass of the equipment is particularly relevant in the case of a motor mounted on a mobile structure, such as for example a propulsion motor of a vehicle.

[0008] However, these devices may encounter problems of loss of fixation of the stator during operation, due to the difference between the coefficients of thermal expansion between the two materials constituting respectively the stator and the side walls of the housing.

[0009] Indeed, the stator is usually held in position in the housing by radial clamping applied by the side walls. However, the aluminum alloy walls tend to expand more than the stator made of ferrous material when the internal temperature of the equipment rises during its operation. This results in a loss of clamping of the stator, which can cause rotation of the stator and / or off-centering, compromising operation and creating risks of accident.

[0010] Thus, an aim of the invention is to provide electrical equipment whose casing is made at least in part of lightweight materials, allowing good heat dissipation and simplified assembly of the equipment, while guaranteeing the fixing and centering of the stator during operation.

[0011] To this end, the invention relates to electrical equipment of the aforementioned type, in which the stator comprises a plurality of fixing conduits extending parallel to the axis emerging on either side of the stator,

[0012] the equipment comprising a plurality of bars extending in the conduits and having ends fixed to the flanges,

[0013] the circumferential wall having at least one slot passing through an entire thickness of the circumferential wall and extending from one flange to the other.

[0014] Such equipment allows the bars to play the role of fixing the stator usually fulfilled by the housing. The housing is then dedicated to the protection of the stator and to heat dissipation, which allows the use of a less rigid structure allowing better adaptation to the differences in thermal expansion between components of the motor. The reduced rigidity of the walls, obtained by the more flexible material and the slot, also makes it easier to assemble the equipment.

[0015] According to particular embodiments, the equipment according to the invention has one or more of the following characteristics, taken in isolation or in any technically feasible combination:

[0016] - for each bar, each flange comprises a perforation opening into view of the conduit in which the bar extends, one of the ends of the bar being engaged in the perforation;

[0017] - the electrical equipment comprises between three and six regularly distributed bars around the axis, in particular four bars;

[0018] - the slot extends substantially parallel to the axis;

[0019] - the housing comprises a flexible seal arranged in the slot;

[0020] - the circumferential wall is formed by at least two separate pieces assembled by at least one external weld bead extending parallel to the axis, in particular produced by a friction stir welding process;

[0021] - the circumferential wall is manufactured by extrusion in at least one die;

[0022] - the equipment is an electric motor comprising a shaft arranged in space internal, mobile in rotation around the axis, the shaft carrying a magnetic rotor;

[0023] - the first material has a coefficient of thermal expansion greater than the co efficient thermal expansion of the second material.

[0024] The invention also relates to a vehicle, in particular road or rail, comprising equipment as described above.

[0025] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings, among which:

[0026] - [Fig.l] [Fig.l] is a side view of a vehicle according to an embodiment of the invention;

[0027] - [Fig.2] [Fig.2] is a schematic longitudinal sectional view of equipment electric according to a first embodiment of the invention;

[0028] - [Fig.3] [Fig.3] is a schematic cross-sectional view of the equipment of [Fig.l]; and

[0029] - [Fig.4] [Fig.4] is a schematic cross-sectional view of a piece of equipment electric according to a second embodiment of the invention.

[0030] A vehicle 10 is shown in [Fig.l], comprising a body 12 and wheels 14.

[0031] The vehicle 10 is a road transport vehicle, intended to accommodate passengers in a compartment 16 defined by the body 12.

[0032] The vehicle 10 is an electrically powered vehicle, and comprises an electric motor 20, a battery 22 powering the electric motor 20 and a transmission device 24 transmitting a motor torque from the electric motor 20 to the wheels 14.

[0033] Alternatively, the vehicle 10 is a hybrid propulsion vehicle. By “hybrid” is meant that the vehicle 10 comprises at least one internal combustion engine in addition to the electric motor 20, the two motors operating alternately and / or simultaneously, depending on the driving conditions.

[0034] Alternatively, the vehicle 10 is a railway vehicle, for example an urban or peri-urban transport vehicle, or a medium or high-speed train.

[0035] The electric motor 20 is partially shown in Figures 2 and 3.

[0036] The electric motor 20 comprises a protective casing 30 delimiting a substantially cylindrical internal space 32, as well as a stator 34 and a shaft 36 carrying a rotor 38, contained in the internal space 32.

[0037] The electric motor 20 also comprises rolling bearings 40 carrying the shaft 36 and a plurality of bars 44 for fixing the stator 34 to the housing 30.

[0038] The electric motor 20 is described below with reference to an axis A defining an axial direction. The axis A is the central axis of the cylinder formed by the internal space 32, and extends parallel to the shaft 36, at the center thereof.

[0039] By the terms “axial” and “axial direction” is meant that which is oriented substantially parallel to the axis A.

[0040] By the term "radial" or "radial direction" is meant that which is oriented substantially perpendicular to the axis A.

[0041] In the example shown, the motor 20 is a synchronous electric motor.

[0042] The housing 30 comprises a lateral circumferential wall 46 having an annular shell shape around the cylindrical internal space 32, substantially parallel to the axial direction, and two end flanges 48 closing the internal space 32 at both ends, spaced from each other in the axial direction.

[0043] The housing 30 is intended to contain the rotor 38 and the stator 34 and to protect them from the outside.

[0044] The circumferential wall 46 has a substantially cylindrical internal face 50, extending opposite the internal space 32, and arranged in contact with the stator 34.

[0045] The circumferential wall 46 is made of a first material.

[0046] The first material is a metallic material which has significant thermal conduction and low density. The first material is for example an aluminum alloy.

[0047] Advantageously, the circumferential wall 46 is produced by extrusion in a die, with an extrusion direction parallel to the axis A. This greatly simplifies the manufacture of the circumferential wall 46.

[0048] As shown in [Fig. 3], the circumferential wall 46 has at least one slot 51 passing through an entire thickness of the circumferential wall 46 and extending from one flange to the other. By “passing through an entire thickness of the circumferential wall”, it is meant that the slot 51 extends continuously between the internal space 32 and the exterior of the housing 30.

[0049] The slot 51 extends for example substantially parallel to the axis A.

[0050] As a variant (not shown), the slot 51 extends in a direction forming a non-zero angle with the axis A, and then has a substantially helical shape.

[0051] The slot 51 is for example produced by milling in the circumferential wall 46.

[0052] The slot 51 reduces the rigidity of the circumferential wall 46 and allows for deformations larger formations in the radial and orthoradial directions. This allows the housing 30 to better adapt to different thermal deformations between the stator 34 and the circumferential wall 46, as explained below.

[0053] Advantageously, a flexible seal 53 is arranged in the slot 51. By “flexible” is meant that the stiffness of the material forming the seal 53 is negligible compared to the stiffness of the first material. The seal 53 is for example made of polymer material, and makes it possible to isolate the internal space 32 from the outside without significantly increasing the rigidity of the circumferential wall 46.

[0054] Advantageously, the circumferential wall 46 defines a plurality of cooling ducts 55. The ducts 55 extend through the circumferential wall 46, in particular parallel to the axis A, over the entire periphery of the circumferential wall 46.

[0055] The conduits 55 allow circulation of cooling fluid in the housing 30. This further improves heat dissipation through the circumferential wall 46, and further reduces the total mass of the housing 30. In addition, the fa extrusion construction of the circumferential wall 46 greatly simplifies the formation of the conduits 55.

[0056] Each end flange 48 has substantially the shape of a flat disc, and has a circular central opening 52, centered on the axis A, receiving one of the rolling bearings 40 and allowing the shaft 36 to pass through.

[0057] Each flange 48 defines a plurality of through perforations 54, for example four perforations, regularly distributed around the axis A.

[0058] The flanges 48 are for example made with the first material.

[0059] Alternatively, the flanges 48 are made with another material, for example cast iron, steel, or steel alloy.

[0060] The stator 34 is mounted in the internal space, in a fixed manner relative to the housing 30.

[0061] The stator 34 is capable of generating a magnetic field in the internal space 32 in order to drive the rotor 38 and the shaft 36 in rotation.

[0062] The stator 34 comprises a magnetic core 56, for example made up of a stack of laminated sheets, which allows electromagnetic interaction between the rotor 38 and the stator 34.

[0063] The stator 34 further comprises an electrical winding (not shown), for its power supply.

[0064] The stator 34 defines a plurality of fixing conduits 58 oriented in the axial direction A, which extend through the magnetic core 56.

[0065] Each conduit 58 passes through and opens out on either side of the magnetic core 56 in the axial direction opposite one of the perforations 54. The conduit 58 is suitable for receiving one of the bars 44.

[0066] The equipment 20 advantageously comprises between three and six bars 44 distributed regularly around the axis A and received in the conduits 58, in particular four bars 44. This makes it possible to better guarantee the maintenance and centering of the stator 34.

[0067] The laminated sheets extend substantially perpendicular to the central axis A.

[0068] The laminated sheets are for example assembled together by weld beads extending substantially parallel to the axis A.

[0069] The magnetic core 56 is made with a second material, having ferromagnetic properties, for example steel.

[0070] The magnetic core 56 is arranged in radial abutment against the internal face 50 of the circumferential wall 46, under normal temperature and pressure conditions. By normal conditions, we mean a temperature substantially between 10°C and 30°C and an atmospheric pressure, i.e. close to 1013 hPA.

[0071] In particular, during the assembly of the motor 20, the circumferential wall 46 is heated to expand it and increase the internal diameter of the internal surface 50. The magnetic core 56 is then placed cold in the circumferential wall 46, so as to obtain good contact once the circumferential wall 46 has cooled to room temperature.

[0072] The circumferential wall 46 is advantageously mounted with greater tightening than in the electric motors of the state of the art. The lower rigidity of the circumferential wall 46, obtained thanks to the slot 51, allows this greater level of tightening without increased risk of material damage.

[0073] The first material and the second material have thermal expansion properties that are different from each other.

[0074] In particular, the second material expands less than the first material when they are subjected to comparable temperature increases.

[0075] The first material has a coefficient of thermal expansion greater than the coefficient of thermal expansion of the second material.

[0076] For example, the first material has a coefficient of thermal expansion greater than or equal to 0.018 mm / m / °C, in particular greater than or equal to 0.022 mm / m / °C.

[0077] For example, the second material has a coefficient of thermal expansion less than or equal to 0.016 mm / m / °C, in particular less than or equal to 0.012 mm / m / °C.

[0078] The internal space 32 is for example likely to undergo a temperature rise of 60°C to 120°C above the ambient temperature.

[0079] When the temperature in the internal space 32 rises, the magnetic core 56 and the circumferential wall 46 expand. Since the circumferential wall 46 is made of the first material and the magnetic core 56 is made of the second material, they expand in different ways.

[0080] However, the greater tightening permitted by the reduced rigidity of the circumferential wall 46 conferred by the slot 51 makes it possible to maintain the support of the magnetic core 56 on the circumferential wall 46. The stator 34 is held in position by the bars 44.

[0081] The shaft 36 is rotatable relative to the housing 30 and the stator 34, around the central axis A. The shaft 36 is carried by the rolling bearings 40, so that its rotational movement takes place with reduced friction.

[0082] The shaft 36 has a substantially cylindrical shape in the internal space 32, and defines two shoulders 60 at its ends engaged in the rolling bearings 40, so as to block the movements of the shaft 36 in the axial direction.

[0083] The rotor 38 comprises a set of coils electrically connected to a collector (not shown), adapted to drive the rotation of the shaft 36 under the effect of an electric field generated by the stator 34.

[0084] Alternatively, the rotor 38 comprises a plurality of permanent magnets connected to the collector.

[0085] The rotor 38 and the stator 34 are separated by an air gap e.

[0086] The rolling bearings 40 comprise, for example, ball bearings. The rolling bearings 40 are arranged between the shaft 36 and the flanges 48, so as to allow the rotation of the shaft 36 relative to the housing 30 with reduced friction.

[0087] Each bar 44 has a middle part 62 and two ends 64, opposite in the axial direction.

[0088] The middle portion 62 extends into the conduit 58, and the ends 64 are fixed to the flanges 48.

[0089] The ends 64 are advantageously threaded over at least part of their length, and have diameters smaller than a diameter of the middle part.

[0090] Advantageously, each perforation 54 comprises a counterbore 66 partially receiving the middle part of the bar 44. This allows better support of the bar 44.

[0091] Advantageously, each flange 48 comprises sleeves 68 extending each perforation 54 and defining the counterbores 66. The sleeves then receive the ends 64 of the bars 44 as well as a fraction of the middle part 66.

[0092] Each sleeve 68 bears against the magnetic core 56 so as to hold the magnetic core in place in the axial direction, and to keep the magnetic sheets clamped together.

[0093] Each bar 44 receives two clamping members 72 engaged on the threaded parts of the ends 64, bearing on the flanges 48 on sides opposite the magnetic stator 56.

[0094] For example, the clamping members 72 are nuts having an external diameter larger than the internal diameter of the perforation, so that the nut bears against the flange 48, in the axial direction. This allows simplified assembly of the bars 44.

[0095] As a variant, the ends 64 have tapped threaded holes extending in the axial direction, from the end 64 towards the middle part 62. The clamping members 72 are then screws engaged in the threaded holes, each screw comprising a head with an external diameter larger than an internal diameter of the perforation 54, so that the screw head bears against the flange 48, in the axial direction.

[0096] Alternatively, the ends 64 of the bars 44 are not threaded, and are directly fixed to the flanges 48, for example by welding.

[0097] According to a second embodiment shown in [Fig.4], the circumferential wall 46 comprises at least two separate parts 80 assembled by at least one external weld bead 82.

[0098] The parts 80 are arranged angularly all around the axis A, so as to form the circumferential wall 46.

[0099] Each external weld bead 82 extends parallel to the axis A, between two parts 80 of the circumferential wall 46.

[0100] The slot 51 is formed between two parts 80, which are not joined by an external weld bead 82 at this location.

[0101] The external weld beads 82 are notably produced by a friction stir welding process.

[0102] The production of the circumferential wall 46 in several separate pieces is made possible by the greater flexibility permitted for the circumferential wall 46, and greatly simplifies the production of the housing 30.

[0103] According to another embodiment, the motor 20 is an asynchronous motor. The rotor 38 then comprises a set of bars and rings forming a cage, known as a squirrel cage.

[0104] According to another embodiment, the electric motor 20 is not a propulsion motor of a vehicle, but a static electric motor, in particular an industrial motor.

[0105] According to another embodiment, the electrical equipment according to the invention is not an electric motor 20 as described above, but another type of electrical equipment comprising a protective housing containing a magnetic stator and a rotor mounted on a rotating shaft.

[0106] For example, the electrical equipment is an alternator, the shaft of which is driven by a turbine, and in which the interaction between the rotor and the stator produces electrical power.

[0107] The electrical equipment 20 according to the invention makes it possible to use a lighter and better thermally conductive material to produce the protective housing, while having improved resistance to thermal expansion, in particular that resulting from its operation.

[0108] It ensures the centering of the stator despite these differences in thermal expansion, which reduces the risks of loss of efficiency and accidents, and improves the durability of the motor over time.

Claims

Claims

1. Electrical equipment (20), in particular for a vehicle, comprising: - a protective housing (30) comprising a lateral circumferential wall (46) made of a first material and two end plates (48), the housing (30) delimiting a substantially cylindrical internal space (32) defined around a central axis (A), - a stator (34) made of at least a second material, arranged in the internal space (32) around the axis (A), characterized in that the stator (34) comprises a plurality of fixing conduits (58) extending parallel to the axis (A) opening on either side of the stator (34), the equipment (20) comprising a plurality of bars (44) extending in the conduits (58) and having ends (64) fixed to the plates (48), the circumferential wall (46) having at least one slot (51) passing through an entire thickness of the circumferential wall (46) and extending from one flange (48) to the other.

2. Electrical equipment (20) according to claim 1, in which, for each bar (44), each flange (48) comprises a perforation (54) opening opposite the conduit (58) in which the bar (44) extends, one of the ends (64) of the bar (44) being engaged in the perforation (54).

3. Electrical equipment (20) according to claim 1 or 2, in which the electrical equipment (20) comprises between three and six bars (44) regularly distributed around the axis (A), in particular four bars (44).

4. Electrical equipment (20) according to any one of claims 1 to 3, wherein the slot (51) extends substantially parallel to the axis (A).

5. Electrical equipment (20) according to any one of claims 1 to 4, wherein the housing (30) comprises a flexible seal (53) disposed in the slot (51).

6. Electrical equipment (20) according to any one of claims 1 to 5, in which the circumferential wall (46) is formed by at least two separate parts (80) assembled by at least one external weld bead (82) extending parallel to the axis (A), in particular produced by a friction stir welding process.

7. Electrical equipment (20) according to any one of claims 1 to 6, wherein the circumferential wall (46) is manufactured by extrusion in at least one die.

8. Equipment (20) according to any one of claims 1 to 7, in which the equipment (20) is an electric motor comprising a shaft (36) arranged in the internal space (32), movable in rotation around the axis (A), the shaft carrying a magnetic rotor (38).

9. Equipment (20) according to any one of claims 1 to 8, wherein the first material has a coefficient of thermal expansion greater than the coefficient of thermal expansion of the second material.

10. Vehicle (10), in particular road or rail, comprising equipment (20) according to any one of claims 1 to 9.

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