ELECTRIC MACHINE WITH REINFORCED SEALING END RING STATOR

Abstract

An electrical machine (MME), for example equipping a vehicle, comprises a rotor (RM) rotatably mounted in a stator (SM) comprising a stack of laminations (ET) housed in a casing (CM) and having a radial face (FR2) in front of which is placed an end ring (AE2) having an intermediate part (PI2) suitable for receiving oil between a first annular seal (JA1), bearing in an axial direction against this radial face (FR2), and a second annular seal (JA2), bearing against an internal face (FI) of the casing (CM) in a radial direction perpendicular to the axial direction. Figure 3

Description

Title of the invention: ELECTRIC MACHINE WITH STATOR WITH END RING WITH REINFORCED SEALING Technical field of the invention

[0001] The invention relates to electric machines with stator and rotor and supplied with oil, and more precisely to the sealing with respect to oil in certain parts of such electric machines. State of the art

[0002] In certain technical fields, such as vehicles (possibly automobiles), stator and rotor electrical machines are used, supplied with oil ensuring at least lubrication. For example, in a vehicle this type of electrical machine can be part of a powertrain (or GMP), purely electric or hybrid (thermal and electric), and be responsible for providing engine torque to move it. It should be noted that this type of electrical machine can be associated with an inverter (or "inverter") capable of electrically supplying this electrical machine, as well as possibly a reducer.

[0003] Generally, the electrical machine is supplied with oil by a first circuit which is connected to an exchanger capable of inducing an exchange of calories between this oil and a heat transfer fluid circulating in a second (cooling) circuit. In the presence of an inverter, the latter is capable of being cooled by the heat transfer fluid before it reaches the exchanger via an intermediate part of the second circuit.

[0004] The exchanger makes it possible to cool the oil which supplies, in particular, the electrical machine, so that it ensures not only the lubrication of certain active parts of the rotor and the stator of the electrical machine, but also the cooling of these active parts. Among these active parts, we can notably cite what those skilled in the art call the coil ends (or coil ends) of the stator.

[0005] These buns are placed in front of the two opposite radial faces of the lamination stack of the stator, inside which the rotor can rotate. In order to lubricate and cool these buns in a targeted manner, they are surrounded respectively by two end rings which are also placed respectively in front of the two radial faces of the lamination stack, and which each comprise an intermediate part receiving the oil and provided with a series of through holes for the passage and distribution of this received oil. Each intermediate part of an end ring must therefore be sealed by two distant annular seals.

[0006] Currently, the sealing provided by the two annular seals of one of the two end rings poses a problem due to the significant dimensional variations of the stack of laminations (typically + / - 3 mm along the axial direction of the stator). Indeed, the problematic end ring comprises a first annular seal which bears along an axial direction of the stator against the corresponding radial face of the stack of laminations, and a second annular seal which bears along this axial direction against a bearing or radial step defined in the internal face of the casing housing the stator and the rotor of the electrical machine. It will be noted that the axial support of the second annular seal against this bearing or radial step results from the axial pressure which is exerted by an end cover which is mounted in a sealed manner on the casing.Since the end ring is made of a flexible plastic material to absorb the dimensional variations of the stack of sheets, it is mainly its intermediate part located between its two annular seals which becomes deformed (or curved) when the axial dimension of the stack of sheets is greater than a predefined average value. However, this situation prevents the first annular seal from correctly ensuring its sealing function, so that oil leaks can occur at the level of the relevant radial face of the stack of sheets, which in particular impairs the cooling of the neighboring bun. In addition, when the first annular seal ages, the risk of oil leakage is increased because it hardens and loses its elasticity.

[0007] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0008] It proposes in particular for this purpose an electrical machine comprising a rotor mounted for rotation in a stator comprising a stack of sheets housed in a casing and having a radial face in front of which is placed an end ring having an intermediate part suitable for receiving oil between a first annular seal bearing in an axial direction of the stator against this radial face and a second annular seal bearing against an internal face of the casing.

[0009] This electrical machine is characterized by the fact that the second annular seal bears against the internal face of the casing in a radial direction which is perpendicular to the axial direction.

[0010] Thanks to the invention, when the axial dimension of the stack of sheets is greater than a predefined average value, the entirety of the second end ring can deform to absorb the significant increase in axial dimension, and therefore the first and second annular seals can correctly perform their sealing function, without risk of oil leakage.

[0011] The electrical machine according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0012] - in a first embodiment, the internal face of the casing may comprise a part which is parallel to the axial direction and on which the second annular seal rests in the radial direction;

[0013] - in a second embodiment, the internal face of the casing may comprise a part which is inclined at an acute angle relative to the axial direction and on which the second annular seal rests in the radial direction;

[0014] - in the second embodiment, the acute angle can be between 1° and 10°;

[0015] - it may comprise a bun placed in front of the radial face of the stack of sheets and surrounded by the end ring. In this case, the intermediate part of the end ring may include through holes suitable for supplying oil to this bun;

[0016] - it may comprise an end cover mounted in a sealed manner on the casing and exerting on one end of the end ring, opposite the radial face of the stack of sheets, pressure in the axial direction in order to press the first annular seal in this axial direction against this radial face.

[0017] The invention also provides a vehicle, possibly of the automobile type, and comprising:

[0018] - a first circuit in which circulates oil suitable for lubrication and a heat exchange and connected to an exchanger capable of inducing an exchange of heat between this oil and a heat transfer fluid circulating in a second circuit, and

[0019] - a powertrain (or GMP) comprising an electric machine of the type of that presented above and supplied by the first circuit with oil from the exchanger.

[0020] For example, this vehicle may also include an inverter capable of electrically powering the electric machine and being cooled by the heat transfer fluid before it reaches the exchanger via an intermediate part of the second circuit.

[0021] Also for example, this vehicle can also include a reducer capable of receiving a motor torque delivered by the electric machine and supplied with lubricating oil by the first circuit. Brief description of the figures

[0022] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings (some of which were obtained in CAD / CAM (“Computer Aided Design / Computer Aided Drawing”)), in which:

[0023] [Fig.l] schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a cooling circuit and a GMP comprising an exemplary electric (motor) machine according to the invention,

[0024] [Fig.2] schematically illustrates, in a perspective view, part of a example of a stator of an electric (motor) machine according to the invention,

[0025] [Fig.3] schematically and functionally illustrates, in a sectional view in an axial and vertical plane, a part of a first example of embodiment of an electric (motor) machine according to the invention, and

[0026] [Fig.4] schematically and functionally illustrates, in a sectional view in an axial and vertical plane, a part of a second exemplary embodiment of an electric (motor) machine according to the invention. Detailed description of the invention

[0027] The invention aims in particular to propose an MME electric machine with SM stator and RM rotor, supplied with oil and with reinforced sealing.

[0028] In the following, it is considered, by way of non-limiting example, that the electric machine MME is intended to be part of a powertrain (or GMP) of a vehicle V, for example of the automobile type. But the invention is not limited to this application. Indeed, an electric machine MME according to the invention can equip any electrical system or device, and in particular all vehicles (land, sea (or river) or air), devices (possibly household appliances), installations (possibly industrial) and electrified buildings. Furthermore, an electric machine MME according to the invention is not necessarily part of a GMP, and therefore is not necessarily capable of providing engine torque.

[0029] Furthermore, it is considered in the following, by way of non-limiting example, that the vehicle V comprises a powertrain (or GMP) of the all-electric type (and therefore whose drive is provided exclusively by an electric (motor) machine MME according to the invention). But the GMP could be of the hybrid type (thermal and electric).

[0030] Furthermore, it is considered in the following, by way of non-limiting example, that the electric (motor) machine MME is supplied with electrical energy by a main (or “traction” or even “power”) battery BP, rechargeable during recharging phases (external or by internal torque recovery). But the electric (motor) machine MME could be supplied with electrical energy by a fuel cell.

[0031] [Fig.l] schematically shows a vehicle V comprising an electric GMP (and therefore an electric (motor) machine MME according to the invention), an inverter OM, a reducer RD, a main (or traction or power) battery BP, a supervision computer CS, a first circuit Cl, and a second (cooling) circuit C2.

[0032] The GMP is part of a transmission chain, and is, here, purely electric. It therefore comprises at least one electric (motor) machine MME according to the invention arranged so as to provide engine torque to move the vehicle V when it is electrically powered, here with alternating voltage and current by the inverter OM, from the direct electrical energy stored (here) in the main battery BP.

[0033] The operation of the GMP is supervised by a supervision computer CS.

[0034] The main battery BP may, for example, comprise electrical energy storage cells, possibly electrochemical (for example of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type). Also for example, the main battery BP may be of the low voltage type (typically 450 V for illustration purposes). But it could be of the medium voltage or high voltage type.

[0035] The electric motor MME is here coupled, via a reducer RD, to a transmission shaft which is itself coupled to at least one set of driving wheels of the vehicle V, preferably via a differential. For example, this set can be located in the front part of the vehicle V. But it could be located in the rear part of the vehicle V.

[0036] Furthermore, and as illustrated in [Fig.l], the electric motor MME is supplied with oil by the first circuit C1, which is connected to an exchanger EC capable of inducing an exchange of calories between this lubricating oil and a heat transfer fluid circulating in the second (cooling) circuit C2. It will be noted that in the example illustrated non-limitingly in [Fig.l] the first circuit C1 also supplies the reducer RD with oil. But this is not an obligation.

[0037] It will also be noted that in the example illustrated non-limitingly in [Fig.l] the first circuit C1 also comprises a reservoir RH storing and collecting the oil, a filter FH, and a pump PH sucking the oil from the reservoir RH to inject it, via the filter FH, into the exchanger EC. The latter (EC) comprises a first output which supplies a part of the first circuit C1 which is (here) connected to the reducer RD to supply it with oil, and the first circuit C1 comprises another part which interconnects an output of the reducer RD to an input of the electric motor MME in order to supply the latter (MME) with oil. This oil then circulates in another part of the first circuit C1 which supplies the reservoir RH.

[0038] Also as illustrated in [Fig.l], the inverter OM is capable of being cooled by the heat transfer fluid before it reaches the exchanger EC via a first intermediate part PAU of the second circuit C2.

[0039] For example, and as illustrated non-limitingly in [Fig.l], the second circuit C2 may comprise a radiator RR installed downstream of the exchanger EC, and capable of cooling the heat transfer fluid. In this case, the second circuit C2 may comprise a second intermediate part PAI2 interconnecting (directly or indirectly) a second outlet of the exchanger EC to the radiator RR, and yet another intermediate part interconnecting (directly or indirectly) an outlet of the radiator RR to an input of the OM inverter.

[0040] It should be noted that the second circuit C2 can be dedicated to cooling the inverter OM and the oil. But this is not obligatory. Indeed, it could also be used to cool at least one other piece of equipment or component of the vehicle V.

[0041] As partially illustrated in Figures 3 and 4, an electrical machine MME, according to the invention, comprises a rotor RM rotatably mounted in a stator SM and a casing CM housing these stator SM and rotor RM.

[0042] As illustrated at least partially in Figures 2 to 4, the stator SM notably comprises a stack of laminations (or lamination stack) ET, first CH1 and second CH2 coil ends (or coil ends), first AE1 and second AE2 end rings (or end-rings), and a cover CE.

[0043] The stack of laminations ET is housed in the casing CM, comprises a central (and axial) housing in which the rotor RM is rotatably mounted, and has first FRI and second FR2 opposite radial faces. Here, the term "radial face" means a face which is parallel to a radial direction dr which is perpendicular to the axial direction da of the stator SM and the rotor RM. This axial direction da is also parallel to the axis of rotation of the rotor RM.

[0044] As illustrated at least partially in Figures 2 to 4, the first end ring AE1 and the first bun CH1 are placed in front of the first radial face FR1, and the first end ring AE1 surrounds the first bun CH1. Similarly, the second end ring AE2 and the second bun CH2 are placed in front of the second radial face FR2, and the second end ring AE2 surrounds the second bun CH2.

[0045] Furthermore, the first end ring AE1 has a first intermediate part PII which is suitable for receiving oil from the first circuit C1 between a first annular seal JAI' (visible in FIGS. 3 and 4) and a second annular seal JA2' (visible in [Fig. 2]). For example, the oil supply to the first intermediate part PII can be done via a channel defined in the casing CM.

[0046] The first annular seal JAI' bears in the axial direction da against the first radial face FRI of the stack of sheets ET, and the second annular seal JA2' bears in the axial direction da against a wall, not shown, of the electrical machine MME and located opposite the first annular seal JAI'.

[0047] The first intermediate part PII of the first end ring AE1 (which receives the oil in a sealed manner thanks to the first JAI' and second JA2' annular seals) is provided with a series of first through holes TT1 which allow the passage and distribution of this oil received towards the first bun CH1 (see [Fig.2]). This not only allows the first bun CH1 to be lubricated, but also the latter (CH1) to be cooled.

[0048] The second end ring AE2 has a second intermediate part PI2 which is suitable for receiving oil from the first circuit C1 between a first annular seal JAI (visible in FIGS. 3 and 4) and a second annular seal JA2 (visible in FIGS. 2 to 4). For example, the oil supply to the second intermediate part PI2 may be via a channel defined in the casing CM (which may also optionally supply the first intermediate part PII).

[0049] The first annular seal JAI bears in the axial direction da against the second radial face FR2 of the stack of sheets ET, and the second annular seal JA2 bears against the internal face FI of the casing CM in the radial direction dr (perpendicular to the axial direction da).

[0050] It will be understood that in an electrical machine MME according to the invention the second annular seal JA2 no longer bears against the internal face FI of the casing CM in the axial direction da (at a radial step or bearing), but in the radial direction dr. This is particularly advantageous because, when the axial dimension of the stack of sheets ET is greater than a predefined average value, the entirety of the second end ring AE2 can deform (curve) to absorb the significant increase in axial dimension of the stack of sheets ET, and not just its second intermediate part PI2.As a result, the first JAI and second JA2 annular seals can correctly perform their sealing function, and therefore there is no longer any risk of oil leakage occurring either at the second radial face FR2 of the stack of sheets ET or at the internal face FI of the casing CM, including when the first JAI and second JA2 annular seals age, and therefore harden and lose their elasticity.

[0051] In a first embodiment illustrated non-limitingly in [Fig. 3], the internal face FI of the casing CM may comprise a part PI which is parallel to the axial direction da and on which the second annular seal JA2 rests in the radial direction dr.

[0052] In a second embodiment illustrated non-limitingly in [Fig. 4], the internal face FI of the casing CM may comprise a part PI which is inclined at an acute angle relative to the axial direction da and on which the second annular seal JA2 rests in the radial direction dr.

[0053] For example, this acute angle can be between 1° and 10°. As an illustrative example, this acute angle can be equal to 5°. But other values ​​can be chosen for this acute angle, the important thing being that there is no radial step or bearing in the entire zone where the second annular seal JA2 can potentially rest on the internal face FI taking into account the possible dimensional variations of the stack of sheets ET.

[0054] Also for example, and as illustrated non-limitingly in Figures 2 to 4, the second intermediate part PI2 of the second end ring AE2 (which receives the oil in a sealed manner thanks to the first JAI and second JA2 annular seals) can be provided with a series of second through holes TT2 which allow the passage and distribution of this oil received towards the second bun CH2. This not only allows the second bun CH2 to be lubricated optimally (due to the absence of leakage), but also optimally cools this second bun CH2 (due to the absence of leakage), and therefore increases the service life of the stator SM.

[0055] Furthermore, and as illustrated non-limitingly in Figures 3 and 4, the end cover CE can be mounted in a sealed manner (via an annular seal) on the casing CM and can exert on one end of the second end ring AE2, opposite the second radial face FR2, a pressure in the axial direction da in order to press the first annular seal JAI in this axial direction da against the second radial face FR2.

Claims

Claims

1. Electrical machine (MME) comprising a rotor (RM) rotatably mounted in a stator (SM) comprising a stack of laminations (ET) housed in a casing (CM) and having a radial face (FR2) in front of which is placed an end ring (AE2) having an intermediate part (PI2) suitable for receiving oil between a first annular seal (JAI), bearing in an axial direction of said stator (SM) against said radial face (FR2), and a second annular seal (JA2), bearing against an internal face (FI) of said casing (CM), characterized in that said second annular seal (JA2) bears against said internal face (FI) in a radial direction perpendicular to said axial direction.

2. Electrical machine according to claim 1, characterized in that said internal face (FI) comprises a part (PI) parallel to said axial direction and on which said second annular seal (JA2) rests in said radial direction.

3. Electrical machine according to claim 1, characterized in that said internal face (FI) comprises a part (PI) inclined at an acute angle relative to said axial direction and on which said second annular seal (JA2) rests in said radial direction.

4. Electrical machine according to claim 3, characterized in that said acute angle is between 1° and 10°.

5. Electrical machine according to one of claims 1 to 4, characterized in that it comprises a bun (CH2) placed in front of said radial face (FR2) of the stack of sheets (ET) and surrounded by said end ring (AE2), and in that said intermediate part (PI2) of the end ring (AE2) comprises through holes (TT2) suitable for supplying oil to said bun (CH2).

6. Electrical machine according to one of claims 1 to 5, characterized in that it comprises an end cover (CE) mounted in a sealed manner on said casing (CM) and exerting on one end of said end ring (AE2), opposite said radial face (FR2), a pressure in said axial direction in order to press said first annular seal (JAI) in said axial direction against said radial face (FR2).

7. Vehicle (V) comprising a powertrain and a first circuit (Cl) i) in which circulates oil suitable for lubrication and heat exchange and ii) connected to an exchanger (EC) suitable for induce an exchange of calories between said oil and a heat transfer fluid circulating in a second circuit (C2), characterized in that said powertrain comprises an electric machine (MME) according to one of claims 1 to 6, supplied by said first circuit (Cl) with oil from said exchanger (EC).

8. Vehicle according to claim 7, characterized in that it comprises an inverter (OM) capable of electrically supplying said electrical machine (MME) and of being cooled by said heat transfer fluid before it reaches said exchanger (EC) via an intermediate part (PAU) of said second circuit (C2).

9. Vehicle according to claim 7 or 8, characterized in that it comprises a reducer (RD) capable of receiving a motor torque delivered by said electric machine (MME) and supplied with oil by said first circuit (Cl).

10. Vehicle according to one of claims 7 to 9, characterized in that it is of the automobile type.

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