Casing for a rotary electric machine

Abstract

A casing (1) for a rotary electric machine, comprising a casing outer part (2) and a casing inner part (3) which form between them passages for a cooling fluid (3a), the casing inner part (3) comprising, at a first end (4a), at least one fixing portion (5) having at least one orifice (6) designed to receive a fixing element (7) connecting the casing inner part (2) to the casing outer part (3), and comprising a second end (4b), which has no fixing portion and lies opposite the first end (4a) along a longitudinal axis (X) of the machine, a clearance (J) being provided between the fixing portion (5) and the casing outer part (2), and a contact surface (9) between the casing inner part (3) and the casing outer part (2) being provided at the second end (4b).

Description

[0001] Description

[0002] Title: Rotating electrical machine casing

[0003] The present invention claims priority from French application 2313172 filed on November 28, 2023, the content of which (text, drawings and claims) is incorporated herein by reference.

[0004] Technical field

[0005] The present invention relates to the field of casings for rotating electrical machines.

[0006] The machines may be synchronous or asynchronous, with alternating current. They may be traction or propulsion machines for electric motor vehicles (Battery Electric Vehicle) and / or hybrid vehicles (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle), such as individual cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and / or energy production applications, in particular naval, aeronautical or wind power.

[0007] Prior art

[0008] It is known to want to ensure the cooling of such a machine by the use of a water core and to ensure the transmission of torque between the stator and the casing by the mounting of fixing means.

[0009] Applications US 2020 / 0144879 and EP 4 109 719 describe machines comprising fixing means arranged between a main casing and a sleeve casing, without axial stop on the side opposite the fixing means.

[0010] Applications US 2017 / 0047809, US 2023 / 0223814 and JP 2019 221054 describe machines comprising two contact surfaces between a main casing and a sleeve casing, on either side, without clearance provided at the level of the fixing means.

[0011] Application US 2017 / 217301 discloses a machine comprising an outer casing and an inner casing fitted together. The outer casing has a conical inner surface and the inner casing has a conical outer surface. Application WO 2020 / 213052 discloses a machine in which the outer and inner parts of the casing are fixed to a first end of the inner casing by screwing and have, at a second end, portions fixed by pressure.

[0012] A flat support is used in a known manner at the interface between the main casing and the liner casing, at the level of the fastening means. The other end of the liner casing remains free. The tension and therefore the rigidity of the liner casing are therefore not uniform. The behavior at the end of the liner casing can have a greater amplitude of radial displacement. The transmission of torque from the stator is only linked to the clamping force of the fastening means and the support surface at the interface. For reasons of manufacturing and limited space, more torque cannot be transmitted.

[0013] There is therefore a need to better control the transmission of torque between the stator and the casing, so that the stator does not start rotating.

[0014] Statement of the invention

[0015] The present invention meets all or part of this need by proposing a rotating electrical machine casing, comprising an outer casing part and an inner casing part, providing between them one or more passages for a cooling fluid, the inner casing part comprising at a first end at least one fixing portion, the fixing portion having at least one orifice arranged to receive a fixing element connecting the inner casing part to the outer casing part, and comprising a second end without a fixing portion, opposite the first end along a longitudinal axis X of the machine, a clearance being provided between the fixing portion of the inner casing part and the outer casing part, and a contact surface between the inner casing part and the outer casing part being provided at the second end of the inner casing part.

[0016] The "longitudinal axis" of a part refers to the line joining all the barycenters of the cross-sections of the part. The "longitudinal axis X of the machine" refers to the axis of rotation of the machine.

[0017] The term "outer casing part" means an outer casing of the machine, in particular a main casing. The term "inner casing part" means a secondary casing, for example a liner casing. The inner and outer casing parts may be a liner casing and a main casing respectively.

[0018] The outer casing portion may be more rigid than the inner casing portion. Alternatively, the outer casing portion may be less rigid than the inner casing portion. Alternatively, the inner and outer casing portions may be of substantially similar rigidity.

[0019] The invention makes it possible to ensure that one of the ends of the inner part of the casing remains free, without compromising the uniformity of the tension and therefore the rigidity of said inner part of the casing within the machine. In particular, at the second end, the inner part and the outer part of the casing are not fixed to each other by radial pressure. The radial pressure may correspond in particular to a hooping between two parts.

[0020] In the invention, there is a separation between the functions of fixing the inner part of the casing to the outer part of the casing and of transmitting torque between the casing and a stator of the machine. The maximum torque of the machine can be between 50 and 500 Nm, better between 60 and 200 Nm.

[0021] The invention makes it possible to increase the mechanical tension in the casing and thus to reduce the micro-displacements of the inner part of the casing, particularly at its second end, and thus to reduce the impact of noise and acoustic vibrations.

[0022] The invention makes it possible to obtain the rotational stop of a stator of the machine relative to the inner part of the casing, or casing sleeve, by an axial force. The axial force is provided by the tightening of the fixing element and the stressing of the inner part of the casing between its fixing portion and the contact surface with the outer part of the casing, which makes it possible to stiffen the inner part of the casing.

[0023] Thus, we obtain that the machine torque is contained by the stator, which does not rotate, the torque transmission being carried out between the stator and the casing by friction on the contact surface. The transmission is carried out at the second end, that is to say opposite to the tightening which is done at the first end.

[0024] The force transmission is done by friction, to lock the stator by adhesion in the inner part of the casing, and the inner part of the casing in the outer part of the casing by adhesion at the contact surface. In particular, the flat support at the second end of the inner part of the casing is configured to transmit the axial force generated by the tightening of the fixing element to the second end of the inner part of the casing by putting the inner part of the casing under mechanical tension.

[0025] Adhesion is obtained by tightening the fixing element in the hole of the fixing portion and in the external part of the casing, in particular in a thread of the latter.

[0026] The hole can be through. It passes through the fixing portion along the longitudinal axis X of the machine.

[0027] The outer casing portion may include a thread arranged in the extension of the orifice, in order to allow the passage of the fixing element from the orifice of the fixing portion towards the outer casing portion.

[0028] The coolant can be a liquid, especially water.

[0029] Summary of the invention

[0030] Game

[0031] The 'clearance' can be referred to in English as 'mechanical clearance'.

[0032] It is usually sought to limit the play at the level of the fixing means between a main casing and a liner casing. On the contrary, in the invention, a play is provided between the fixing portion of the inner part of the casing and the outer part of the casing.

[0033] The clearance between the fixing portion of the inner casing part and the outer casing part is provided at the level of the fixing element inserted between the inner and outer casing parts. The clearance can extend in a radial plane around the fixing element received in the hole of the fixing portion of the inner casing part.

[0034] The clearance is provided at the first end of the inner part of the casing. The clearance is provided between two radial portions of the inner part of the casing, along a plane normal to the longitudinal axis X.

[0035] The clearance is present after tightening the fastener. After tightening, there is no contact between the inner and outer housing parts at the clamping element. The clearance ensures that the torque transmission between the inner and outer housing parts is done through the contact surface. The clearance ensures that all the tension put into the fastener is not dispersed in the contact surface. The clearance at the fastener allows tension to be applied through the inner housing part to the contact surface between the inner and outer housing parts.

[0036] The presence of clearance ensures that the inner part of the casing is stressed and thus properly stiffened. The clearance present in the fastener helps to solidify the assembly. The clearance allows the tension of the fastener to be applied through the inner part of the casing to the contact surface. If there were no clearance, the tension applied to the casing would be dispersed at the fastening portion.

[0037] In addition, the clearance between the inner and outer part of the casing helps to reduce noise and acoustic vibrations of the machine and to overcome machining defects.

[0038] In the invention, a tension is applied in the clamping element without reaching contact between the inner and outer housing portions at the clamping element.

[0039] This provides tension to the inner part of the casing along its entire length. The second end of the inner part of the casing is held securely, due to the contact surface with the outer part of the casing. The casing is therefore stronger at both ends and more resistant to shocks.

[0040] The clearance between the mounting portion of the inner casing and the outer casing can be adjustable. The clearance can be adjusted during the design or development phase of the machine. This ensures stable clearance throughout the machine's lifetime.

[0041] The clearance may be sufficient to ensure contact-free clamping between the inner and outer parts of the housing. At the same time, the clearance may be sufficient to compensate for thermal expansion between the inner and outer parts of the housing. The clearance may also not be too large in order to minimize the axial dimensions, along the longitudinal axis X of the machine.

[0042] Such a clearance dimensioning allows the entire inner part of the casing to be tensioned, particularly between its two ends. During manufacturing, a tolerance of plus or minus 0.8 mm may be applied to the clearance.

[0043] The fastener generates an axial force to keep the inner part of the casing and the outer part of the casing under tension. The tightening of the fastener can be adjustable during the design and development phases of the machine. Adjustable means a clearance at the level of the fastener that can be modulated. The tightening of the fastener can be modified according to the desired torque transmission. This avoids modifying the casing, in particular the diameter of the inner part of the casing. The clearance at the level of the fastener allows the inner part of the casing to be stressed. It also stiffens the inner part of the casing and reduces the impact of noise and acoustic vibrations regardless of the tension applied to the casing and without taking into account machining defects. The clearance therefore makes it possible to increase the stiffness of the casing.The adjustable or modular clearance can thus be modified according to the desired torque transmission and also avoid the modification of the parts used if defects exist after assembly of the machine.

[0044] The clearance can be between 0.5 mm and 40 mm, better between 0.7 mm and 10 mm, better between 1 mm and 3 mm, for example being of the order of 1.2 mm or 1.6 mm.

[0045] The clearance may be extended by a recessed portion, which may have an annular shape around the longitudinal axis X, positioned radially between the clearance and the longitudinal axis X. The shape of this recessed portion may allow a balance to be obtained between the flexibility and rigidity of the fixing portion. It allows it to be given flexibility in a controlled manner.

[0046] Fixing portion

[0047] The fixing portion(s) are provided at the first end of the inner part of the casing.

[0048] The fixing portion may have at its radial end a substantially triangular-shaped protrusion, extending beyond the outer part of the casing. This may be referred to as a fixing lug.

[0049] Alternatively, the fixing portion may be radially covered by the outer casing portion.

[0050] The fixing portion(s) may be configured to have sufficient stiffness to prevent their plastic deformation. The aim is to avoid any plasticization of the lug(s) under the stress exerted by the fixing element. The fixing portion extends longitudinally along the longitudinal axis X, over a thickness of the fixing portion. The fixing portion radially overlaps a portion of the outer casing part and allows the inner casing part to be fixed thereto. The inner casing part may be made in a single piece. In particular, the fixing portion may be made in a single piece with the rest of the inner casing part.

[0051] The fixing portion may have a thickness between 4 mm and 50 mm, better between 10 mm and 40 mm, better between 15 mm and 35 mm, being for example of the order of 20 mm or 25 mm.

[0052] The thickness of the fixing portion may be sufficient to prevent any deformation of the fixing portion and to avoid any plastic deformation of the inner part of the casing depending on the living conditions, in particular thermal and vibration.

[0053] A surface of the fixing portion facing the outer casing part may not extend in a radial plane but form a slight angle with a radial plane. This slight angle makes it easier to strip the fixing portion when it is molded.

[0054] The casing may have a single attachment portion or several attachment portions, in particular a single ear or several ears. The casing may have at least two ears, better between 2 and 10 ears, even better between 3 and 8 ears, for example 3 ears.

[0055] The casing may have as many ears as there are fastening elements. Alternatively, the casing may have a different number of ears and fastening elements.

[0056] In one embodiment, each ear may have multiple fasteners. In one embodiment, the inner housing portion may have a single ear having at least one fastener.

[0057] Alternatively, the fixing portion may have a single circular part, preferably of substantially the same diameter as the inner part of the casing, said circular part having at least one fixing element, in particular a plurality of fixing elements.

[0058] Alternatively, the inner housing portion may include at least one attachment portion and one torque transmission portion, which may be separate parts. The torque transmission portion and the attachment portion may be assembled during assembly of the machine. The torque transmission portion and the attachment portion may be assembled axially and in the same direction. The torque transmission portion and the attachment portion may be aligned with each other.

[0059] When the casing has several ears, they can be equally distributed around the circumference of the inner part of the casing. This provides good stability and good distribution of the contact pressure force of the inner part of the casing on the outer part of the casing.

[0060] Alternatively, when the casing has several ears, they may not be equally distributed. They may be arranged at different distances from each other on the circumference. In particular, when the casing has three ears, they may be distributed irregularly, in particular by being spaced apart from each other respectively by an angle of 115° between the first and second ears, by an angle of 115° between the second and third ears, and by an angle of 130° between the third and first ears. This distribution makes it easier to assemble and to adapt to manufacturing and / or environmental constraints.

[0061] The rotating electrical machine may have a single fastening element or a plurality of fastening elements, from the inner part to the outer part of the casing.

[0062] The casing may have at least two fixing elements, better between 2 and

[0063] 10 fasteners, even better between 3 and 8 fasteners, for example 3 fasteners.

[0064] The housing may have the same number of fixing portions as there are fixing elements.

[0065] The fasteners may have a thread. They may be screws.

[0066] These can be M4, M5, M6 or M8 type screws.

[0067] The fastener can be subjected to tension, once it has been tightened, depending on the desired clearance. The tension that the fastener is subjected to can be between 1500 N and 25000 N, better between 3000 N and 15000 N, for example 5000 Newtons.

[0068] Contact surface

[0069] The term “contact surface” refers to all the supports between the inner part of the casing and the outer part of the casing. The contact surface may comprise a single support zone. Alternatively, the contact surface may be multiple, comprising a plurality of support zones, in particular at least two support zones. In one embodiment, the contact surface may comprise at least two support zones.

[0070] The contact surface can thus be continuous or discontinuous, being fractioned. A discontinuous contact surface makes it easier to compensate for any defects in the perpendicularity of said contact surface.

[0071] A discontinuous contact surface can be divided into at least two support zones, for example between 2 and 20 support zones, better between 3 and 9 support zones, for example 6 support zones.

[0072] The contact surface between the inner part of the casing and the outer part of the casing forms a firm stop.

[0073] The contact surface may extend over 360° around the longitudinal axis X, continuously or discontinuously. Alternatively, it may extend over less than 360°, for example over an angular extent of between 120° and 360°, or even between 150° and 320°, or even between 180° and 290°, better still between 210° and 260°.

[0074] In one embodiment, the support zones may be regularly spaced apart.

[0075] A support zone of the contact surface may, for example, extend over an angular extent of between 1° and 30° around the longitudinal axis X, or even over an angular extent of between 2° and 20°, or even over an angular extent of between 3° and 15°.

[0076] Two consecutive support zones can be separated by an angular extent without support of between 1° and 60° around the longitudinal axis X, or even over an angular extent of between 2° and 50°, or even over an angular extent of between 3° and 40°.

[0077] Alternatively, the bearing areas may be irregularly spaced apart. In one embodiment, the bearing areas may be concentrated on a portion of the contact surface.

[0078] The total area of ​​the contact surface can be between 10 and 100 cm 2 , better between 20 cm 2 and 40 cm 2 , for example 25 cm 2 , continuously or in splits.

[0079] In an alternative embodiment, the total surface area of ​​the contact surface between the inner part and the outer part of the casing may be between 20 cm 2 and 600 cm 2 , preferably between 40 cm 2 and 80 cm2 , for example of the order of 58 cm 2 , especially in the case where the contact surface is inclined relative to the longitudinal axis X, as will be described later.

[0080] A height of the contact surface can be between 1 mm and 10 mm, better between 2 mm and 5 mm, being for example about 4 mm. A height of the contact surface is measured radially, between a point of the contact surface closest to the longitudinal axis X and a point of the contact surface furthest from the longitudinal axis X.

[0081] An average radius of the contact surface may be between 50 mm and 150 mm, more preferably between 65 mm and 110 mm, being for example approximately 80 mm. The average radius may be the radius of a central point of the contact surface, in particular a point located at half the height of the contact surface. The central point of the contact surface may also be for example a point located at an equal distance between the point of the contact surface closest to the longitudinal axis X and the point of the contact surface furthest from the longitudinal axis X.

[0082] A ratio between the average radius of the contact surface and the torque transmitted to the stator can be between 0.1 mm / Nm (millimeter divided by Newton meter) and 4 mm / Nm, better between 0.4 mm / Nm and 2 mm / Nm, being for example of the order of 0.65 mm / Nm or 0.9 mm / Nm.

[0083] The contact surface between the inner part and the outer part of the casing may extend radially over a distance around the longitudinal axis X, between 1 mm and 20 mm, better between 2 mm and 10 mm, better between 3 mm and 6 mm, for example of the order of 4 mm.

[0084] The contact surface between the inner and outer housing portions may be positioned at the end of the inner housing portion opposite that comprising the fastening element.

[0085] According to the invention, the contact surface is closer to the second end of the inner casing portion than to the first end of the inner casing portion. It may, for example, be located less than half of the total length of the inner casing portion measured along the longitudinal axis X, or even less than a third, better still less than a quarter, or even less than 1 / 6, or even less than 1 / 8 of the total length of the inner casing portion measured along the longitudinal axis X. The contact surface between the inner and outer casing portions may be positioned beyond a longitudinal end of a stator of the machine, in particular beyond the stator sheet metal stacks. This configuration may make it possible to compensate for vibrations of the stator and better transmit torque to the stator, by friction and prevent rotation of the inner casing portion.

[0086] According to this embodiment, the inner housing part is thus fully tensioned. The position of the contact surface towards the second end of the inner housing part makes it possible to compress said inner housing part and in return to ensure a continuous force making it possible to stiffen the system. The resulting stiffness of the tensioned housing can allow optimal torque transmission.

[0087] The contact surface between the inner part and the outer part of the casing may be flat, extending in particular in a radial plane relative to the longitudinal axis X.

[0088] The outer and inner parts of the casing forming the contact surface can form a firm stop. The angle between the longitudinal axis X and the contact surface is in this case approximately 90°.

[0089] Alternatively, the outer and inner casing portions forming the contact surface may be arranged at a different angle, in particular at an angle greater than or less than 90°. The contact surface between the inner and outer casing portions may be inclined relative to the longitudinal axis X at an angle other than 90°. An angle formed between the contact surface and the longitudinal axis X may be between 2° and 45°, better still between 15° and 30°, preferably 20°. The contact surface may be conical in shape.

[0090] According to this embodiment, the surfaces of the inner and outer casing parts may come into contact, within the contact surface, at an angle with the longitudinal axis other than 90°. The surfaces of the outer and inner casing parts may come into contact, within the contact surface, at an angle greater than or less than 90°. The contact surface may extend between the inner and outer casing parts, the latter being able to be substantially inclined.

[0091] This embodiment allows for better adjustment of the torque transmission. Adding an angle between the longitudinal axis X of the housing and the contact surface increases the tangential force between the inner and outer parts of the housing. Depending on the tightening adjustment of the fastening element, the variation of the tangential force at the contact surface and thus the torque transmission is more precise. This embodiment also allows for the transmission of greater torque with the same size.

[0092] This embodiment makes it possible to tension only the inner part of the casing between its two ends, namely the end comprising the fixing element and that comprising the contact surface, which allows better control of the transmission of the torque.

[0093] In addition, the surface area of ​​the contact surface between the inner portion and the outer portion of the casing may be greater according to this embodiment, as mentioned above.

[0094] The torque transmission and the coefficient of friction between the inner and outer housing parts can be further improved by degrading the surface condition of one or both of the inner and outer housing parts. The contact surface between the inner and outer housing parts can be degraded.

[0095] According to an alternative embodiment, the surface of the inner casing portion may be degraded. According to this alternative embodiment, the surface condition of the inner casing portion may not be smooth. The surface of the inner casing portion may have been deliberately degraded, for example scratched or marked with grooves from a smooth surface. This makes it possible to increase the roughness of the surface of the inner casing portion in order to increase the coefficient of friction.

[0096] The contact surface may include studs and notches, in particular the inner part of the casing having studs and the outer part of the casing having notches of a shape complementary to the studs.

[0097] The pins formed in the inner part of the casing can fit completely or partially into the hollow notches of complementary shape. The notches can be formed by matting in the outer part of the casing, that is to say by local plastic deformation by strong compression. Each pin can thus be embedded in a notch.

[0098] Such a configuration can significantly increase the adhesion between the inner part of the casing and the outer part of the casing. This can be further amplified in the case where the hardness of the inner part of the casing is greater than that of the outer part of the casing. A stud may have a substantially block shape. Alternatively, the stud may have a substantially trapezoidal shape. Alternatively, the stud may be of any other shape.

[0099] In an exemplary embodiment, the stud has a substantially trapezoidal shape formed of three distinct support zones, a central zone and two lateral zones. The two lateral zones may form an angle of substantially 90° with the central zone. Alternatively, the angle may be other than 90°.

[0100] In order to reinforce the rigidity of the casing, the casing may comprise at least one shrink-fitting zone, preferably two shrink-fitting zones. A first shrink-fitting zone may be located near the first end of the casing, between the clearance and a first cooling fluid passage. A second shrink-fitting zone may be located near the contact surface between the inner part and the outer part of the casing, between the contact surface and a final cooling fluid passage.

[0101] The shrinkage can be low, it does not participate in the transmission of torque. It can help avoid assembly and jamming problems while ensuring mechanical contact, in order to limit the impact of noise and acoustic vibrations from the machine.

[0102] Furthermore, an O-ring may be inserted between the inner casing portion, in particular at the first end of the inner casing portion, and the outer casing portion. Alternatively, a plurality of O-rings, for example two, may be inserted between the inner casing portion and the outer casing portion. This or these seals make it possible to ensure the sealing of the cooling fluid.

[0103] The invention also relates to a rotating electrical machine comprising a casing as described above.

[0104] Brief description of the drawings

[0105] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the attached drawing, in which:

[0106] [Fig 1] Figure 1 illustrates a casing according to the invention. [Fig 2] Figure 2 is a general perspective view of the fixing portion of the inner part of the casing.

[0107] [Fig 3] Figure 3 is a longitudinal section of the casing according to the invention.

[0108] [Fig 4] Figure 4 is a detail view of the fixing portion.

[0109] [Fig 5] Figure 5 is a view similar to Figure 3 of an alternative embodiment.

[0110] [Fig 6] Figure 6 is an isolated view of the inner casing portion of an alternative embodiment.

[0111] [Fig 7] Figure 7 is an isolated view of the inner casing portion of another alternative embodiment.

[0112] [Fig 8] Figure 8 is a longitudinal sectional view of the housing of Figure 7.

[0113] [Fig 9] Figure 9 is a detailed view of the contact surface according to the embodiment variant of Figure 8.

[0114] [Fig 10] Figure 10 is a detailed view of the contact surface according to the embodiment variant of Figure 8.

[0115] Detailed description

[0116] Figures 1 to 4 illustrate a casing 1 of a rotating electrical machine. The casing 1 comprises an outer casing part 2 and an inner casing part 3, providing between them one or more passages 3a for a cooling fluid.

[0117] The inner casing part 3 comprises at a first end 4a at least one fixing portion 5. The fixing portion 5 has at least one orifice 6 arranged to receive a fixing element 7 connecting the inner casing part 3 to the outer casing part 2. The orifice 6 is a through hole. It passes through the fixing portion 5 along the longitudinal axis X of the machine.

[0118] The inner part of the casing 3 also comprises a second end 4b without a fixing portion, opposite the first end 4a along a longitudinal axis X of the machine.

[0119] A clearance J is provided between the fixing portion 5 of the inner casing part 3 and the outer casing part 2. A contact surface 9 between the inner casing part 3 and the outer casing part 2 is provided at the second end 4b of the inner casing part 3. Adhesion is obtained by tightening the fixing element 7 in the hole

[0120] 6 of the fixing portion 5 and in the outer casing part 2, in particular in a thread thereof. The outer casing part 2 comprises for this purpose a thread 21 arranged in the extension of the orifice 6, in order to allow the passage of the fixing element 7 from the orifice 6 of the fixing portion towards the outer casing part 2.

[0121] Furthermore, two O-rings 8a and 8b are inserted between the inner casing part 3, in particular at the first end 4a of the inner casing part 3, and the outer casing part 2.

[0122] The clearance J between the fixing portion 5 of the inner casing part 3, illustrated in Figure 2, and the outer casing part 2 is provided at the level of the fixing element

[0123] 7 inserted between the inner 3 and outer 2 casing parts. The clearance J can extend along a radial plane around the fixing element 7 received in the orifice 6 of the fixing portion 5 of the inner casing part 3.

[0124] The clearance J is provided at the first end 4a of the inner casing part 3. The clearance J is provided between two radial portions of the inner casing part 3, along a plane normal to the longitudinal axis X.

[0125] The clearance J is present after tightening the fastening element 6. After tightening, there is no support between the inner 3 and outer 2 housing parts at the tightening element. The clearance J at the fastening element 7 allows tension to be applied through the inner 3 housing part to the contact surface 9 between the inner 3 and outer 2 housing part.

[0126] The J clearance is of the order of 1.4 mm.

[0127] The clearance J provided between the fixing portion 5 of the inner casing part 3 and the outer casing part 2 is adjustable.

[0128] The fixing element 7 generates an axial force making it possible to keep the inner part of the casing 3 and the outer part of the casing 2 under tension.

[0129] The clearance J is extended by a hollow portion 8, illustrated in figure 4, which can have an annular shape around the longitudinal axis X, positioned radially between the clearance J and the longitudinal axis X.

[0130] The fixing portions 5 are provided at the first end 4a of the inner casing part 3. The fixing portion 5 has at its radial end a substantially triangular-shaped protrusion, extending beyond the outer casing part 2. This can be referred to as a fixing lug.

[0131] The fixing portion 5 extends longitudinally along the longitudinal axis X, over a thickness of the fixing portion. The fixing portion 5 radially overlaps a portion of the outer casing part 2 and allows the inner casing part 3 to be fixed there. The fixing portion has a thickness, illustrated in FIG. 4, being for example of the order of 22 mm. The fixing portion 5 may have a protrusion of substantially triangular shape. This can be referred to as an ear.

[0132] The inner part of the casing 3 here comprises three ears 5. The inner part of the casing 3 comprises as many ears as there are fixing elements 7. The ears 5 are not equally distributed around the circumference of the inner part of the casing 3. The fixing elements 7 are screws.

[0133] As illustrated in Figure 3, the contact surface 9 between the inner casing part 3 and the outer casing part 2 forms a firm stop.

[0134] As shown in Figure 3, a height h of the contact surface is approximately 4 mm. The height h of the contact surface is measured radially, between a point on the contact surface closest to the longitudinal axis X and a point on the contact surface farthest from the longitudinal axis X.

[0135] An average radius R of the contact surface is approximately 80 mm. The average radius is the radius of a central point of the contact surface, in particular a point located at half the height of the contact surface. The central point of the contact surface can also be, for example, a point located equidistant between the point of the contact surface closest to the longitudinal axis X and the point of the contact surface furthest from the longitudinal axis X.

[0136] A ratio between the average radius of the contact surface and the torque transmitted to the stator is of the order of 0.5 mm / mN.

[0137] The contact surface 9 between the inner part 3 and the outer part of the casing 2 may extend radially over a distance around the longitudinal axis X, between 1 mm and 2 mm, better between 1 mm and 10 mm, better between 3 mm and 6 mm, for example of the order of 4 mm. The contact surface 9 between the inner 3 and outer parts of the casing 2 is positioned at the end 4b of the inner part of the casing 3 opposite that comprising the fixing element 5.

[0138] According to the invention, the contact surface 9 is closer to the second end 4b of the inner casing part 3 than to the first end 4a of the inner casing part 3. The contact surface 9 between the inner 3 and outer casing parts 3 is positioned beyond a longitudinal end of a stator of the machine.

[0139] In order to ensure the sealing of the cooling fluid, the casing also comprises two shrinking zones 12a and 12b. A first shrinking zone 12b is located near the first end 4a of the casing, between the clearance J and a first cooling fluid passage. A second shrinking zone 12b is located near the contact surface 9 between the inner part 3 and the outer part of the casing 2, between the contact surface 9 and a last cooling fluid passage.

[0140] The total area of ​​the contact surface 9 can be, for example, 25 cm2 , continuously or in splits.

[0141] In the embodiment illustrated in Figures 1 to 4, the contact surface 9 between the inner part 3 and the outer part of the casing 2 is flat, extending in particular in a radial plane relative to the longitudinal axis X. The outer 3 and inner parts of the casing 2 forming the contact surface 9 form a clear stop. The angle between the longitudinal axis X and the contact surface is in this case substantially 90°. According to this embodiment, the contact surface 9 comprises a single bearing zone 10.

[0142] Of course, it does not depart from the scope of the present invention if it is otherwise. By way of example, Figure 5 illustrates an exemplary embodiment in which the outer 3 and inner 2 parts of the casing forming the contact surface 9 are arranged at an angle other than 90°.

[0143] An angle a is provided between the contact surface and the longitudinal axis X and is of the order of 20°, as illustrated in Figure 5.

[0144] The J clearance is of the order of 1.4 mm.

[0145] According to this embodiment variant, the total surface area of ​​the contact surface between the inner part 3 and the outer part 2 of the casing is for example of the order of 58 cm 2 .

[0146] According to an alternative embodiment illustrated in Figure 6, the contact surface 9 of the inner casing part 3 is degraded. According to this alternative embodiment, the state of the contact surface 9 of the inner casing part 3 is not smooth. The contact surface 9 of the inner casing part 3 has been deliberately degraded, by being marked with crossed grooves from a smooth contact surface. This makes it possible to increase the roughness of the contact surface 9 of the inner casing part 3 in order to increase the coefficient of friction.

[0147] In another embodiment variant illustrated in figures 7 to 10, the contact surface 9 is multiple, comprising a plurality of support zones 10. The contact surface 9 is discontinuous and is divided into several support zones. The support zones 10 are regularly spaced apart.

[0148] According to this embodiment variant, a support zone of the contact surface extends over an angular extent c of between 3° and 15°. Two consecutive support zones are separated by an angular extent without support d of between 3° and 40°.

[0149] In this variant embodiment illustrated in figures 6 to 9, the contact surface 9 comprises pins 91 and notches 92, in particular the inner part of the casing 3 having pins 91 and the outer part of the casing 2 having notches 92 of a shape complementary to the pins 91.

[0150] The pins 91 formed in the inner part of the casing 3 fit completely or partially into the hollow notches 92 of complementary shape. The notches 92 are formed by matting in the outer part of the casing, that is to say by local plastic deformation by strong compression. Each pin 91 can thus be embedded in a notch 92.

[0151] The stud 91 has a substantially trapezoidal shape formed of three distinct support zones 10, a central zone 10a and two lateral zones 10b. The two lateral zones 10b can form an angle of substantially 90° with the central zone 10a.

Claims

Claims 1. Rotating electrical machine casing (1), comprising an outer casing part (2) and an inner casing part (3), providing between them one or more passages for a cooling fluid (3a), the inner casing part (3) comprising at a first end (4a) at least one fixing portion (5), the fixing portion (5) having at least one orifice (6) arranged to receive a fixing element (7) connecting the inner casing part (3) to the outer casing part (2), and comprising a second end (4b) without a fixing portion, opposite the first end (4a) along a longitudinal axis (X) of the machine, a clearance (J) being provided along the longitudinal axis (X) between the fixing portion (5) of the inner casing part (3) and the outer casing part (2),and a contact surface (9) between the inner casing part (3) and the outer casing part (2) being provided at the second end (4b) of the inner casing part., 2. Housing according to the preceding claim, in which the clearance (J) provided between the fixing portion (5) of the inner part (3) of the housing and the outer part of the housing (2) is adjustable, being modular.

3. Housing according to any one of the two preceding claims, the clearance (J) being between 0.5 mm and 40 mm, better between 0.7 mm and 10 mm, better between 1 mm and 3 mm.

4. Housing according to any one of the two preceding claims, the fixing portion (5) having a thickness (e) of between 4 mm and 50 mm, better between 15 mm and 35 mm, better between 20 mm and 25 mm, for example of the order of 22 mm.

5. Housing according to any one of the preceding claims, comprising at least two fixing elements (7), better between 2 and 10 fixing elements (7), even better between 3 and 8 fixing elements (7), for example 3 fixing elements (7).

6. Housing according to any one of the preceding claims, comprising the same number of fixing portions (5) as fixing elements (7).

7. Housing according to any one of the preceding claims, the contact surface (9) comprising a single support zone (10).

8. Housing according to any one of claims 1 to 6, the contact surface (9) comprising at least two support zones (10).

9. Housing according to the preceding claim, the support zones (10) being regularly spaced apart.

10. Casing according to any one of the preceding claims, the contact surface (9) between the inner part (3) and the outer part of the casing (2) being flat, extending in particular in a radial plane relative to the longitudinal axis (X).

11. Casing according to any one of claims 1 to 10, the contact surface (9) between the inner part (3) and the outer part (2) of the casing being inclined relative to the longitudinal axis (X) at an angle other than 90°.

12. Housing according to the preceding claim, an angle a provided between the contact surface and the longitudinal axis (X) being between 2° and 45°, better between 15° and 30°, being in particular 20°.

13. Housing according to any one of claims 1 to 9, the contact surface (9) between the inner (3) and outer (2) parts of the housing being degraded.

14. Casing according to any one of claims 1 to 9, the contact surface (9) comprising pins (91) and notches (92), in particular the inner part (3) of the casing having pins (91) and the outer part (2) of the casing having notches (92) of a shape complementary to the pins (91).

15. Housing according to any one of the preceding claims, the inner housing part (3) comprising a torque transmission portion, the torque transmission portion being a separate part from the fixing portion, the torque transmission portion and the fixing portion (5) being assembled axially and in the same direction.

16. Rotating electrical machine comprising a casing (1) according to any one of the preceding claims.

17. Rotating electrical machine according to the preceding claim, comprising a stator having sheet metal packs, the contact surface (9) between the inner (3) and outer (2) casing parts being positioned beyond the sheet metal packs of the stator.

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