Assembly comprising a main housing and a closure housing axially preventing the rotation of a stator

Abstract

The invention relates to an assembly (10) comprising a rotating electrical machine extending along a longitudinal axis X, a main housing (12) intended to house the rotating electrical machine and a closure housing (14). The rotating electrical machine comprises a stator (16). The stator (16) is prevented from rotating about the longitudinal axis X by a first bearing surface (S1) of the closure housing (14) for bearing on the stator (16), located at a first axial end of the stator (16), and by a second bearing surface (S2) of the main housing (12) for bearing on the stator (16), located at a second axial end of the stator (16) opposite the first axial end. The stator (16) is centred with respect to the longitudinal axis X by positioning the main housing (12) around the stator (16).

Description

[0001] Description

[0002] Title: Assembly comprising a main housing and a closing housing that axially locks a rotating stator

[0003] The present invention claims priority from French application 2503240 filed on March 28, 2025, 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 rotating electrical machines, and more specifically to the axial blocking of the stator in rotation during the operating phases of the electrical machine.

[0006] The machines can be synchronous or asynchronous, and alternating current. They can be traction or propulsion machines for electric (Battery Electric Vehicle) and / or hybrid (Hybrid Electric Vehicle - Plug-in Hybrid Electric Vehicle) motor vehicles, such as passenger cars, vans, trucks, or buses. The invention also applies to rotating electrical machines for industrial and / or power generation applications, particularly in the marine, aeronautical, or wind power sectors.

[0007] The stator's rotational locking is a key element in electrical machines, particularly in automotive electrical machines.

[0008] Previous technique

[0009] Currently, most stator rotation locking solutions achieve stator positioning and rotation locking through the same interface, which often consists of a shrink fit on the outer skin of the stator.

[0010] When this is not the case, screws are generally used, positioned through the stator mass. This results in a significant increase in the overall size.

[0011] US patent 2020 / 0144879 A1 discloses an electrical machine in which the stator has an external surface with a rear flange that bears against a rear edge of the main housing. A screw is engaged in a flange in a front area and generates an axial load on the stator to prevent stator movement. The stator's axial restraint is not ensured by a closing housing. EP patent 4,131,743 A1 discloses an electrical machine in which a ring is inserted into an end cap to spray oil onto the coil heads. The end cap rests on the stator to create a seal, not to axially prevent the stator from rotating. The main housing also does not contribute to axially preventing the stator from rotating.

[0012] There is a need for a simple and reliable solution to improve the axial locking of the rotating stator and its centering, in order to avoid mechanical and electrotechnical problems that could lead to the breakdown of the electrical machine.

[0013] Summary of the invention

[0014] The invention aims to meet all or part of this need and achieves this, according to one of its aspects, through an assembly comprising a rotating electrical machine extending along a longitudinal axis X, a main casing intended to house the rotating electrical machine and a closing casing, the rotating electrical machine comprising a stator,

[0015] the stator being blocked from rotation around the longitudinal axis X by a first bearing surface of the closing casing on the stator located at a first axial end of the stator and by a second bearing surface of the main casing on the stator located at a second axial end of the stator opposite the first axial end,

[0016] the centering of the stator with respect to the longitudinal axis X is ensured by the positioning of the main housing around the stator.

[0017] The first and second support surfaces extend perpendicularly to the longitudinal axis X.

[0018] The first axial end of the stator can be located on the coil head side. There can also be a coil head at each axial end of the stator.

[0019] When the electrical machine has a reducer, the second axial end of the stator is located on the reducer side.

[0020] An electrical machine may have one or more stators. An electrical machine may have one or more rotors.

[0021] According to the invention, the end cap and the main housing axially prevent the stator from rotating. This axial blocking, consisting simply of supports, is achieved on one side of the stator by the end cap and on the other side by the main housing. The stator is thus "sandwiched" between the main housing and the end cap. This stacking ensures that the stator is prevented from rotating during the operating phases of the electric machine. The larger the contact diameter at the bearing surfaces, the greater the lever arm, which reduces the axial force accordingly.

[0022] Furthermore, the main housing positions the stator radially, centering it, while the closing housing positions the rotor and ensures the circulation of cooling fluid. A cooling fluid is indeed used to limit heat loss in the stator and rotor of the electric machine, as well as in the gearbox.

[0023] Thus, the invention separates the stator's rotation blocking function and the stator's radial centering function, by implementing them through two distinct interfaces.

[0024] The invention has many advantages.

[0025] Since the stator is centered directly on the main housing, thanks to a small positive assembly clearance, no shrink-fitting is required. The invention therefore offers an advantage in terms of manufacturing process by eliminating the heating of the main housing during assembly, which would be necessary for shrink-fitting. Not only are production methods simplified, but deformations related to component heating (stress relaxation in the casting) are also eliminated, and cycle time is reduced.

[0026] The invention also brings an advantage to the product itself, by offering a low space constraint.

[0027] It also allows, as mentioned above, for the positioning and holding functions of the stator to be separated.

[0028] It offers a simple solution to implement.

[0029] Furthermore, the resulting torque transmission range of the electric machine is significant. The assembly according to the invention can be dimensioned for a torque exceeding 400 Nm.

[0030] Description of the invention

[0031] The closing housing can be tightened onto the main housing along the longitudinal axis X by means of at least one screw located on the periphery of the closing housing and extending along the longitudinal axis X into the closing housing and into the main housing.

[0032] As a non-limiting example, there may be four screws distributed around the periphery of the closing casing so as to be spaced at 90° angles.

[0033] The screws are not used to prevent the stator from rotating, but only to axially tighten the closing housing onto the main housing.

[0034] The axial clamping of the closing housing on the main housing ensures a sufficiently high force on the stator mass.

[0035] The closing cover may have at least one lug through which at least one screw passes. There is one lug per screw.

[0036] Advantageously, sufficiently long screws are used to optimize the control of the applied tension. In effect, the screws act similarly to tie rods, which work in elongation to absorb thermal expansion and maintain screw tension under all conditions of thermal expansion, with temperatures ranging from approximately -50°C to +130°C. Furthermore, increasing the screw length allows for a thinner, and therefore lighter, cover and main housing.

[0037] The cover and main housing can be made of aluminum. The screws and stator mass can be made of steel.

[0038] Since the contact diameters between the stator and the housing, and between the stator and the main housing, are fixed by the stator diameter, the torque resulting from the axial force and the coefficient of friction between the mutually supporting surfaces is a key parameter of the invention. Various embodiments aimed at increasing the coefficient of friction are possible. This will indeed reduce the axial force required and thus allow for a reduction in the size of the housing.

[0039] In one particular embodiment, only the first bearing surface of the end cap on the stator is smooth. In another particular embodiment, only the second bearing surface of the main housing on the stator is smooth. In yet another particular embodiment, both the first bearing surface of the end cap on the stator and the second bearing surface of the main housing on the stator are smooth. A smooth bearing surface is, for example, a machined surface.

[0040] In one particular embodiment, only the first bearing surface of the closing housing on the stator is obtained by a surface treatment adapted to increase its coefficient of friction. In another particular embodiment, only the second bearing surface of the main housing on the stator is obtained by a surface treatment adapted to increase its coefficient of friction. In yet another particular embodiment, both the first bearing surface of the closing housing on the stator and the second bearing surface of the main housing on the stator are obtained by a surface treatment adapted to increase their coefficient of friction.

[0041] In a particular embodiment, the surface of the stator in contact with the first bearing surface of the closing housing on the stator or the surface of the stator in contact with the second bearing surface of the main housing on the stator is obtained by a surface treatment adapted to increase its coefficient of friction.

[0042] In a particular embodiment, at the first axial end of the stator, either the first bearing surface of the housing on the stator, or the corresponding surface of the stator, is obtained by a surface treatment adapted to increase its coefficient of friction; and at the second axial end of the stator, either the second bearing surface of the main housing on the stator, or the corresponding surface of the stator, is obtained by a surface treatment adapted to increase its coefficient of friction. In other words, at each axial end of the stator, one surface on each of the two contacting surfaces is obtained by such a surface treatment.

[0043] The first bearing surface of the closing housing on the stator or the second bearing surface of the main housing on the stator may have a diamond dust coating.

[0044] The stator surface in contact with the first bearing surface of the closing housing on the stator, or the stator surface in contact with the second bearing surface of the main housing on the stator, may have a diamond dust coating.

[0045] Alternatively, the surface treatment may consist of creating a knurled surface. In a particular embodiment, the first bearing surface of the closing housing on the stator and / or the second bearing surface of the main housing on the stator and / or the corresponding surface of the stator may have asperities. For example, an asperity may be a deformation or protrusion created by punching, welding, or sheet metal cutting.

[0046] Since the clamping force varies according to the coefficient of friction, it can have a significant impact on the stator mass. Indeed, depending on whether the stator mass is held in place by welding, clipping, or gluing, the effect on economic efficiency and stator performance will differ. In this respect, clipping represents a good compromise between performance and cost.

[0047] The periphery of the closing housing may include an indexing pin or finger adapted to secure the closing housing to the main housing. The indexing pin helps to prevent the stator from rotating and thus prevents the closing housing from rotating. It is advantageously unique and passes through a lug that can be located anywhere on the periphery of the closing housing. The indexing pin may be in the form of an anti-rotation pin.

[0048] In a particular embodiment where the rotating electrical machine also includes at least one rotor, the closing casing may include a cylindrical part extending along the longitudinal axis X and forming an interface with the rotor, and the centering of the rotor with respect to the longitudinal axis X may be achieved by axial support on the cylindrical part.

[0049] The cylindrical section may include a central coolant circulation channel. This channel carries the coolant from the periphery of the housing towards the rotor.

[0050] The coolant can be a liquid, including oil.

[0051] The assembly may include a bearing forming an interface between the closing housing and the rotor, the bearing having an outer ring disposed inside the rotor and an inner ring disposed around the cylindrical part of the closing housing.

[0052] The internal mounting of the bearing within the shaft allows the assembly to be used in high-speed applications, from 10,000 rpm to 40,000 rpm, ideally around 30,000 rpm. It also saves space and reduces axial compression of the electric motor. The assembly is therefore compact.

[0053] The closing casing may include a skirt and a plurality of ribs extending radially between the cylindrical portion and the skirt. It may also include another plurality of ribs extending radially on its outer portion, opposite its inner portion comprising the cylindrical portion.

[0054] The ribs have several functions: they contribute to the mechanical stiffening of the closing casing, as well as to the acoustic performance of the assembly thanks to the good support of the rotor held by the cylindrical part, and they allow the cooling fluid to be brought back by trickle from the rotor and the coil heads to the internal bearing of the rotor, in order to cool and lubricate the bearing.

[0055] The skirt of the closing casing may have a sloping internal wall to allow the cooling fluid to flow towards the ribs.

[0056] In a particular embodiment, the closing casing is in contact with the main casing in an area distinct from the first bearing surface of the closing casing on the stator. Specifically, the skirt comprises, on the one hand, an end portion with a first thickness, at the end of which is located the first bearing surface on the stator, and on the other hand, a portion upstream of the end portion with a second thickness greater than the first, which is in contact with the main casing. The two parts of the skirt are separated by a shoulder that creates a space between the skirt and the main casing, allowing the circulation of the cooling fluid.

[0057] The assembly may include a seal in an area where the skirt of the closing housing is in contact with the main housing. This seal may be an O-ring.

[0058] The invention also relates to a propulsion device for a motor vehicle, comprising an assembly as defined above, a reducer and an inverter.

[0059] The propulsion system for a motor vehicle may include one or two rotating electrical machines.

[0060] The gearbox may have a single transmission stage. Alternatively, it may have several transmission stages, for example two or three transmission stages.

[0061] The rotating electrical machine(s) can be arranged on either side of the gearbox. Each rotating electrical machine can have a shaft connected to a primary shaft of the gearbox.

[0062] The invention also relates to a motor vehicle comprising a propulsion device as described above. The vehicle may have at least two drive wheels, each of the drive wheels being driven in rotation by the reduction gear, in particular by an output shaft thereof.

[0063] The drive wheels can be arranged on either side of the gearbox. Each drive wheel can have a shaft connected to an output shaft of the gearbox. The device can include a first drive wheel fixed in rotation to a first output shaft of the gearbox. The device can include a second drive wheel fixed in rotation to a second output shaft of the gearbox.

[0064] Brief description of the drawings

[0065] The invention will be better understood upon reading the detailed description that follows, a non-limiting example of its embodiment, and an examination of the attached drawings.

[0066] [Fig 1] Figure 1 is a schematic and partial cross-sectional view of an assembly according to the invention, in a first particular embodiment.

[0067] [Fig 2] Figure 2 is a schematic and partial cross-sectional view of an assembly according to the invention, in a second particular embodiment where the closing housing is lightened.

[0068] [Fig 3] Figure 3 is a schematic and partial cross-sectional view of the whole of Figure 1 along a different cutting plane, showing a detail of the realization.

[0069] [Fig 4] Figure 4 is a schematic and partial cross-sectional view of the whole of Figure 1 along a different cutting plane, showing the cooling fluid circuit.

[0070] [Fig 5] Figure 5 is a schematic perspective view of the closing housing included in the assembly of Figure 1.

[0071] Detailed description

[0072] Figures 1 to 5 illustrate an assembly 10 according to the invention, in particular embodiments of the invention. The assembly 10 comprises a rotating electrical machine extending along a longitudinal axis X.

[0073] The assembly 10 also includes a main casing 12 for housing the rotating electrical machine and a closing casing 14.

[0074] In the non-limiting example described here, the electric machine comprises a stator 16 and a rotor 18.

[0075] According to the invention, the stator 16 is blocked in rotation around the longitudinal axis X by a first bearing surface SI of the closing housing 14 on the stator 16 located at a first axial end of the stator 16, the bearing surface SI extending perpendicularly to the axis X and by a second bearing surface S2 of the main housing 12 on the stator 16 located at a second axial end of the stator 16 opposite to the first axial end, the bearing surface S2 extending perpendicularly to the axis X.

[0076] The area of ​​the first support surface SI can be between 10 cm 2 and 80 cm 2 , ideally between 20 cm 2 and 50 cm 2 For example, it is approximately 38 cm 2 .

[0077] According to the invention, the centering of the stator 16 with respect to the longitudinal axis X is ensured by the positioning of the main housing 12 around the stator 16.

[0078] As shown in Figures 1 and 2, the closing cover 14 is tightened onto the main cover 12 along the longitudinal axis X by means of at least one screw 20 located on the periphery of the closing cover 14. In the example described here, the assembly comprises four screws 20 equally spaced around the periphery of the closing cover 14 and thus spaced at 90° angles. The four screws 20 extend along the longitudinal axis X into the closing cover 14 and into the main cover 12.

[0079] The diameter of the 20 screws can be between 3 mm and 14 mm, preferably between 5 mm and 10 mm. For example, it is around 6 mm.

[0080] The length of the 20 screws can be between 10 mm and 200 mm, preferably between 40 mm and 160 mm. For example, it is around 120 mm.

[0081] Figure 2 is similar to Figure 1, except that in the embodiment of Figure 1, the assembly 10 includes a lighter and thinner closing housing 14.

[0082] As shown in Figures 1 and 2, the closing housing 14 has at least one lug 22 respectively through which a screw 20 passes. In the example described here, the assembly 10 has four lugs 22.

[0083] In the example described here, the bearing surfaces SI and S2 are smooth and the surfaces of the stator 16 respectively in contact with the bearing surfaces SI and S2 have a diamond dust coating.

[0084] The coefficient of friction between the closing housing 14 and the stator 16 can be between 0.01 and 1, preferably between 0.1 and 0.7. For example, it is around 0.55.

[0085] As shown in Figure 3, the periphery of the closing housing 14 has an indexing pin 24 adapted to make the closing housing 14 integral with the main housing 12 and to block the closing housing 14 from rotation, which allows the first bearing surface SI to contribute to blocking the rotation of the stator 16. Figure 5 shows a lug 25 adapted to be passed through by the indexing pin 24.

[0086] As shown in figures 1 to 5, the closing housing 14 has a cylindrical part 26 extending along the longitudinal axis X and forming an interface with the rotor 18. The centering of the rotor 18 with respect to the longitudinal axis X is achieved by axial support on the cylindrical part 26.

[0087] The cylindrical part 26 includes a central conduit 28 for the circulation of cooling fluid.

[0088] Figure 4 shows the internal cooling fluid circuit.

[0089] The circuit includes, in particular, a fluid inlet to the stator 16, which is in the form of a supply ring 30.

[0090] The inner wall of the main casing 12 has axial fluid circulation channels in its thickness which guide the fluid towards a recovery ring 32 disposed at the outlet of the axial channels and formed between the main casing 12 and the closing casing 14. The recovery ring 32 is adapted to collect and evacuate the cooling fluid heated by the thermal losses of the active part of the stator 16 to an evacuation outlet equipped with a pump.

[0091] In addition, the arrows on Figure 4 indicate the direction of fluid flow towards the rotor 18, via the central conduit 28 of the cylindrical part 26.

[0092] As shown in Figures 1 to 4, the assembly 10 further comprises a bearing 34 forming an interface between the closing housing 14 and the rotor 18. The bearing 34 comprises an outer ring disposed inside the rotor 18 and an inner ring disposed around the cylindrical part 26 of the closing housing 14.

[0093] As shown in Figure 5, the closing housing 14 comprises a skirt 36 and a plurality of ribs 38 extending radially between the cylindrical portion 26 and the skirt 36. In the example described here, the closing housing 14 has eight regularly spaced ribs 38. Additional ribs (not visible) may be provided on the opposite face of the closing housing 14 to stiffen its exterior.

[0094] As shown in Figures 1 to 4, the assembly 10 includes a sealing gasket 40 in an area where the skirt 36 of the closure housing 14 is in contact with the main housing 12. This area is distinct from the area where the first bearing surface SI of the closure housing 14 on the stator 16 is located. Indeed, the skirt 36 comprises, on the one hand, an end portion 360 which has a first thickness and at the end of which is located the first bearing surface SI on the stator 16, and on the other hand, a portion 362 upstream of the end portion 360 which has a second thickness greater than the first thickness and which is in contact with the main housing 12. The two portions 360, 362 of the skirt 36 are delimited by a shoulder 364 which creates a space between the skirt 36 and the main housing 12, allowing the circulation of the fluid. cooling.

Claims

1. Claims 1. Assembly (10) comprising a rotating electrical machine extending along a longitudinal axis X, a main casing (12) intended to house the rotating electrical machine and a closing casing (14), the rotating electrical machine comprising a stator (16), the stator (16) being blocked in rotation around the longitudinal axis X by a first bearing surface (SI) of the closing housing (14) on the stator (16) located at a first axial end of the stator (16) and by a second bearing surface (S2) of the main housing (12) on the stator (16) located at a second axial end of the stator (16) opposite to the first axial end, the centering of the stator (16) with respect to the longitudinal axis X being ensured by the positioning of the main housing (12) around the stator (16), the periphery of the closing housing (14) having an indexing pin (24) adapted to make the closing housing (14) integral with the main housing (12).

2. Assembly (10) according to claim 1, the closing housing (14) being tightened on the main housing (12) along the longitudinal axis X by means of at least one screw (20) disposed on the periphery of the closing housing (14) and extending along the longitudinal axis X in the closing housing (14) and in the main housing (12).

3. Assembly (10) according to claim 2, the closure housing (14) comprising at least one lug through which at least one screw (20) passes.

4. Assembly (10) according to claim 1, 2 or 3, the first bearing surface (SI) of the closing housing (14) on the stator (16) or the second bearing surface (S2) of the main housing (12) on the stator (16) being smooth.

5. Assembly (10) comprising a rotating electrical machine extending along a longitudinal axis X, a main casing (12) intended to house the rotating electrical machine and a closing casing (14), the rotating electrical machine comprising a stator (16), the stator (16) being blocked in rotation around the longitudinal axis X by a first bearing surface (SI) of the closing housing (14) on the stator (16) located at a first axial end of the stator (16) and by a second bearing surface (S2) of the main housing (12) on the stator (16) located at a second axial end of the stator (16) opposite the first axial end, the centering of the stator (16) with respect to the longitudinal axis X being ensured by the positioning of the main housing (12) around the stator (16), the first bearing surface (SI) of the closing housing (14) on the stator (16) or the second bearing surface (S2) of the main housing (12) on the stator (16) being obtained by a surface treatment adapted to increase its coefficient of friction.

6. Assembly (10) comprising a rotating electrical machine extending along a longitudinal axis X, a main casing (12) intended to house the rotating electrical machine and a closing casing (14), the rotating electrical machine comprising a stator (16), the stator (16) being blocked in rotation around the longitudinal axis X by a first bearing surface (SI) of the closing housing (14) on the stator (16) located at a first axial end of the stator (16) and by a second bearing surface (S2) of the main housing (12) on the stator (16) located at a second axial end of the stator (16) opposite to the first axial end, the centering of the stator (16) with respect to the longitudinal axis X being ensured by the positioning of the main housing (12) around the stator (16), the surface of the stator (16) in contact with the first bearing surface (SI) of the closing housing (14) on the stator (16) or the surface of the stator (16) in contact with the second bearing surface (S2) of the main housing (12) on the stator (16) being obtained by a surface treatment adapted to increase its coefficient of friction.

7. Assembly (10) according to claim 5 or 6, the first bearing surface (S1) of the closing housing (14) on the stator (16) or the second bearing surface (S2) of the main housing (12) on the stator (16) having a diamond dust coating.

8. Assembly (10) according to claim 5 or 6, the surface of the stator (16) in contact with the first bearing surface (S1) of the closing housing (14) on the stator (16), or the surface of the stator (16) in contact with the second bearing surface (S2) of the main housing (12) on the stator (16), comprising a diamond dust coating.

9. Assembly (10) according to any one of the preceding claims, the rotating electrical machine further comprising at least one rotor (18), the closing housing (14) comprising a cylindrical part (26) extending along the longitudinal axis X and forming an interface with the rotor (18), the centering of the rotor (18) with respect to the longitudinal axis X being achieved by axial support on the cylindrical part (26).

10. Assembly (10) according to the preceding claim, the cylindrical part (26) comprising a central conduit (28) for circulating cooling fluid.

11. Assembly (10) according to one of the two preceding claims, comprising a bearing (34) forming an interface between the closing housing (14) and the rotor (18), the bearing (34) comprising an outer ring disposed inside the rotor (18) and an inner ring disposed around the cylindrical part (26) of the closing housing (14).

12. Assembly (10) according to any one of the three preceding claims, the closure housing (14) comprising a skirt (36) and a plurality of ribs (38) extending radially between the cylindrical part (26) and the skirt (36).

13. Assembly (10) according to the preceding claim, comprising a sealing gasket (40) in an area where the skirt (36) of the closing housing (14) is in contact with the main housing (12).

14. Propulsion device for motor vehicle, comprising an assembly (10) according to any one of the preceding claims, a reducer and an inverter.

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