Electric Machine

Abstract

The device (52) for cooling an electric machine (2) of a motor vehicle comprises a groove (44) and a circuit (53) fluidically connected to the groove (44). The groove (44) is intended to be located radially with respect to the axis (6) of the electric machine (2) between the housing (4) of the electric machine (2) and the stator (20) of the electric machine (2).

Description

Technical Field

[0001] The present invention relates to the field of cooling devices for electric machines, and more particularly to electric machines intended to be equipped for land, sea or air vehicles. Background Art

[0002] Electric or electric hybrid propulsion motor vehicles conventionally include a drive train equipped with an electric machine. The electric machine is usually cooled by a cooling device, which includes a circuit and a tank (also called an oil sump). The tank is located below the electric machine. The circuit is supplied with fluid through the tank and includes a plurality of parts, which are thermally connected to the stator and / or rotor of the electric machine.

[0003] This arrangement allows cooling of the electric machine, but is not entirely satisfactory. On the one hand, the cooling device takes up a considerable amount of space within the limited space of the engine compartment. Moreover, if the vehicle is tilted too far or the road has a steep gradient, failure of the hydraulic fluid circulation pump may occur, thereby interrupting the cooling of the electric machine. Summary of the invention

[0004] In view of the above, an object of the present invention is to allow cooling of an electric machine while alleviating the above mentioned disadvantages.

[0005] More specifically, an object of the invention is to increase the compactness of the cooling device while limiting its sensitivity to the inclination of the vehicle or the gradient of the road.

[0006] To this end, a cooling device for an electric machine of a motor vehicle is proposed, which comprises a tank and a circuit which is fluidically connected to the tank.

[0007] According to a general feature of this device, the slot is intended to be positioned radially with respect to the axis of the electric machine, between the casing of the electric machine and the stator of the electric machine, and over the entire circumference around the axis of the electric machine.

[0008] This placement of the slots makes it possible to increase the compactness of the cooling device, in particular by limiting the vertical offset between the axis of the electric machine and the bottom portion of the slots and by making the slots use the space above and to the sides of the stator. In addition, the high-pressure hydraulic fluid contained in the slots contributes to cooling the stator of the electric machine.

[0009] In one embodiment, the circuit comprises a first peripheral compartment axially offset relative to the slot.

[0010] By limiting the vertical offset between the axis of the electric machine and the bottom part of the tank and by thus dividing the cooling device, the dispersion of the fluid in the event of a tilt of the device is limited. In doing so, the sensitivity of the cooling device to a severe tilt of the vehicle or a great gradient of the road is thereby limited.

[0011] There may also be provided first annular sealing means at right angles to the axis of the electric machine, the first sealing means being inserted axially between the groove and the first peripheral compartment.

[0012] In one embodiment, the circuit comprises a channel fluidically connected to the slot and an injection device connected to the channel and emerging in the first peripheral compartment, the injection device being intended to be arranged axially facing the windings of the rotor of the electric machine.

[0013] The arrangement of the slots between the housing and the stator makes it possible to cool the stator and therefore does not require the arrangement of injection means to cool the stator. By arranging the injection means axially facing the rotor windings, the rotor is cooled more efficiently, while improving compactness and at the same time reducing the production costs of the device.

[0014] Advantageously, the circuit comprises a second peripheral compartment, the groove being inserted axially between the first and second peripheral compartments, and the device comprises a second annular sealing device at right angles to the axis of the electric machine, the second sealing device being inserted axially between the groove and the second peripheral compartment.

[0015] A number of different configurations can be envisaged for the circuit downstream of the peripheral compartment and upstream of the tank. Among these configurations, the following variants given as non-limiting examples can be envisaged in particular.

[0016] According to a first variant, the circuit comprises a pump, an output pipe, and an injection pipe connecting the pump to the tank, the output pipe comprising a first upstream portion fluidically connected to the first peripheral compartment, a second upstream portion fluidly connected to the second peripheral compartment, and a downstream portion connecting the first upstream portion, the second upstream portion and the pump.

[0017] This first variant makes it possible, in particular, to increase the compactness of the device by using a single pump.

[0018] According to a second variant, the circuit comprises a first pump, a first output pipe fluidically connected to the first peripheral compartment, a second pump, a second output pipe fluidically connected to the second peripheral compartment, and an injection pipe comprising a first upstream portion, a second upstream portion, and a downstream portion connecting the first upstream portion, the second upstream portion and the tank, the first pump connecting the first output pipe to the first upstream portion, and the second pump connecting the second output pipe to the second upstream portion.

[0019] This second variant makes it possible to minimize the risk of pump failure.This variant is therefore more particularly suitable for demanding applications such as electric traction machines of all-terrain vehicles or electric machines embedded in aircraft.

[0020] In one embodiment, the circuit includes a check valve disposed on the output conduit.

[0021] This limits the risk of the pump failing if the vehicle tilts too far.

[0022] In another embodiment, the circuit includes an equalizing pipe fluidly connected to the first peripheral compartment and the second peripheral compartment, the equalizing pipe including a nozzle and a ball disposed in the nozzle.

[0023] In the event that the levels of the hydraulic fluid in the peripheral compartments are unbalanced, for example due to a pronounced tilt, the equalization conduit makes it possible to restore the balance between the hydraulic fluid levels.

[0024] In one embodiment, the device comprises means for managing the temperature of the hydraulic fluid contained in the tank, the management means being able to drive the supply of the stator of the electric machine.

[0025] Such a management device makes it possible to control the temperature of the hydraulic fluid without having to incorporate fluid heating devices, in order simply to optimize the cooling implemented by the device.

[0026] According to another aspect, an electric machine for a powertrain of a motor vehicle, preferably an electric or hybrid propulsion electric vehicle, is proposed, the electric machine comprising a housing, a stator and a device as defined previously. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other objectives, characteristics and advantages of the invention will become apparent from a reading of the following description given purely as a non-limiting example and with reference to the accompanying drawings, in which:

[0028] - Figure 1 is a perspective view of an electric machine according to one aspect of the present invention,

[0029] - Figure 2 yes Figure 1 A longitudinal cross-sectional view of an electric machine,

[0030] - Figure 3 A cooling device according to an embodiment of the present invention is schematically shown, and

[0031] - Figure 4 A cooling device according to another embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0032] Reference Figure 1 and Figure 2, an electric machine 2 has been schematically represented. In the example shown, the electric machine 2 is intended to be incorporated into the drive train of an electric or hybrid electric propulsion motor vehicle (not shown). However, of course, it would not depart from the context of the invention when the electric machine 2 is incorporated into another device, such as an aerial vehicle (such as an aircraft).

[0033] The electric machine 2 comprises in particular a housing 4 which is axisymmetric about an axis of symmetry 6. A direct orthogonal vector basis 8 attached to the housing 4 is defined. The basis 8 consists of vectors vector and vector Composition. Vector Parallel to axis 6.

[0034] In this application, unless otherwise indicated, the terms "axial", "axially", "radial", "radially" and "circumferential" are to be understood as being relative to the axis 6. Furthermore, the term "cylindrical" is to be understood according to its conventional definition, i.e. a cylindrical surface is a surface consisting of straight lines of a given direction passing through a given curve.

[0035] The housing 4 comprises a first housing part 10 and a second housing part 12. A radially outer flange 14 extends at one axial end of the first housing part 10. A radially outer flange 16, whose form corresponds to the form of the radially outer flange 14, extends at the axial end of the second housing part 12. The first housing part 10 and the second housing part 12 are in axial contact with each other, in particular via the radially outer flanges 14 and 16. The first housing part 10 and the second housing part 12 are fixed by a plurality of threaded rods 18. In this particular case, eleven threaded rods 18 are used to fix the first housing part 10 and the second housing part 12.

[0036] The electric machine 2 includes a stator 20 arranged inside the housing 4. The stator 20 is wound around a vector The stator 20 particularly comprises a body 22 and a winding 24. The body 22 is cylindrical about the axis 6 and has a circular axial cross section. Figure 2 As shown, the winding 24 particularly includes a left lead 26 and a right lead 28, which are axially located on both sides of the stator body 22. The stator body 22 and the left lead 26 are received inside the first housing portion 10. The right lead 28 extends axially outside the first housing portion 10 and is received inside the second housing portion 12.

[0037] The electric machine 2 includes a rotor 30. The rotor 30 is rotatable around a vector The rotor 30 comprises a shaft 32 and a body 34. The shaft 32 is mounted to rotate relative to the housing 4 around the axis 6. The body 34 is radially delimited by a cylindrical outer surface (not mentioned) having a circular axial cross section around the axis 6. The body 34 receives a winding, which in particular comprises a left lead 36 and a right lead 38.

[0038] The electric machine 2 includes a silicone rim 40. The rim 40 is placed on the axial front end surface 41 of the first housing portion 10. The axial front end surface 41 is in axial contact with the axial front end surface 22g of the body 22 via the rim 40. The rim 40 forms a continuous loop on the circumference of the axial front end surface 41. More specifically, the rim 40 is disposed in a direction parallel to the vector In the example shown, the ring formed by the rim 41 is predominantly circular with four local radial widenings.

[0039] The electric machine 2 comprises an annular seal 42. The seal 42 is substantially flat. The seal 42 is axially inserted between the radially outer flanges 14 and 16. The seal 42 comprises a radially inner end (not mentioned) axially in contact with the axial front end surface 22d of the body 22. In the illustrated example, the seal 42 is constituted by a metal washer. However, it is conceivable that the seal 42 is constituted by a washer made of another material (e.g. rubber), or by two washers made of two different materials juxtaposed relative to each other (e.g. a metal washer and a rubber washer juxtaposed) without departing from the scope of the present invention.

[0040] The rim 40 and the seal 42 thus form sealing means axially located on either side of the body 22. By means of these sealing means, the interior of the housing 4 is divided into a groove 44, a first peripheral compartment 46, and a second peripheral compartment 48. The groove 44 is axially inserted between the first peripheral compartment 46 and the second peripheral compartment 48. The groove 44 extends over the entire circumference around the axis 6, in other words, the groove 44 completely surrounds the axis 6 and the stator 20. The groove 44 is tightly delimited relative to the compartment 46 by the rim 40. Similarly, the groove 44 is tightly separated from the second peripheral compartment 48 by the seal 42. It is obvious that the sealing means can be reversed, that is to say replacing the rim 40 with a seal and / or replacing the seal 42 with a silicone rim, without departing from the scope of the invention.

[0041] The first peripheral compartment 46 and the second peripheral compartment 48 each include a filter 50 in their bottom portion. The filter 50 is capable of collecting the hydraulic fluid contained in the first peripheral compartment 46 and the second peripheral compartment 48. More specifically, the filter 50 is in contact with the hydraulic fluid layer formed in the bottom of the first peripheral compartment 46 and the second peripheral compartment 48 and can thereby collect the hydraulic fluid from these layers.

[0042] Reference Figure 3, the electric machine 2 comprises a cooling device 52. For the sake of clarity of the drawings, Figure 3 Schematically, an electric machine 2 is shown in FIG. 1 , wherein certain elements of the electric machine 2 are intentionally omitted. Similarly, in order to make the drawings clearer, Figure 1 and Figure 2 The cooling device 52 is omitted. The cooling device 52 comprises in particular the groove 44 and a circuit 53, which circuit comprises in particular a first peripheral compartment 46 and a second peripheral compartment 48, respectively strictly delimited by sealing means (rim 40 and seal 42). The groove 44 and the circuit 53 exchange hydraulic fluid, which may in particular comprise oil.

[0043] The circuit 53 comprises a high-pressure channel 54, the function of which is to distribute the hydraulic fluid contained in the groove 44 to the first peripheral compartment 46 and the second peripheral compartment 48. The high-pressure channel 54 comprises an upstream portion 56 fluidically connected to the groove 44. The high-pressure channel 54 comprises a first downstream portion 58 and a second downstream portion 60. The first downstream portion 58 and the second downstream portion 60 are fluidically connected to the upstream portion 56. Each portion (the first downstream portion 58 and the second downstream portion 60) comprises a nozzle 62, 64, respectively. The nozzle 62 is present in the compartment 46. The nozzle 64 is present in the compartment 48. More specifically, each nozzle 62, 64 is axially arranged facing the lead-out lines 36, 38, respectively. Although nozzles are used to spray the hydraulic fluid, it is of course possible to use another distribution device or another spraying device.

[0044] The circuit 53 includes an output conduit 66. The output conduit 66 includes a first upstream portion 67 fluidly connected to the filter 50 of the compartment 46 and a second upstream portion 68 connected to the filter 50 of the compartment 48. Each portion (the first upstream portion 67 and the second upstream portion 68) includes a check valve 69 that blocks flow to the associated filter 50. The output conduit 66 includes a downstream portion 70 fluidly connected to the first upstream portion 67 and the second upstream portion 68.

[0045] The circuit 53 comprises an equalizing conduit 71 connecting the first upstream portion 67 and the second upstream portion 68. More specifically, the connection point of the equalizing conduit 71 to each portion (the first upstream portion 67 and the second upstream portion 68) is upstream of the associated non-return valve 69. The equalizing conduit 71 comprises a nozzle 72 with an equalizing ball 73. In this way, if the vehicle tilts, the equalizing conduit 71 is blocked by the ball 73. If the vehicle is level, the ball 73 is displaced to the middle of the nozzle 72 and hydraulic fluid can flow into the equalizing conduit 71 to restore the balance between the hydraulic fluid level in the first peripheral compartment 46 and the hydraulic fluid level in the second peripheral compartment 48. Although in the illustrated example, a nozzle and a ball are used to create the equalizing conduit 71, of course any other way of creating the opening and closing of the flow of fluid in the equalizing conduit 71 based on the tilt of the vehicle can be envisaged.

[0046] The circuit 53 comprises a high-pressure injection conduit 74. The high-pressure injection conduit 74 is fluidly connected to the tank 44. The circuit 53 further comprises a pump 76 connecting the downstream portion 70 with the high-pressure injection conduit 74.

[0047] The cooling device 52 comprises a temperature sensor 78 inside the tank 44. By means of the temperature sensor 78, the temperature T of the hydraulic fluid contained in the tank 44 can be measured. 44 However, it is conceivable to use other ways to determine the temperature T 44 , such as mapping-based estimators.

[0048] The cooling device 52 comprises a driver module 79 which is informationally linked to the temperature sensor 78 of the electric machine 2 and to a control device (not shown). The driver module 79 is provided with hardware and software components to establish a stator supply current set point. In practice, the driver module 79 is configured to set the stator supply current set point when the temperature T 44 Below the threshold T 44 低阈值 The supply current set point is followed and when the temperature T 44 Above the threshold T 44 高阈值 Therefore, a temperature control circuit for managing the temperature T is provided. 44 way.

[0049] By virtue of this arrangement, the pump 76 generates a flow in the groove 44. The high-pressure hydraulic fluid contained in the groove 44 cools the stator 20 of the electric machine 2. Thus, the temperature T can be driven by modifying the supply current of the stator 20 by means of the drive module 79. 44The high-pressure hydraulic fluid is directed to the nozzles 62 and 64 through the high-pressure passage 54. The nozzle 62 sprays hydraulic fluid into the first peripheral compartment 46 to cool the rotor 30 at the lead-out line 36. Similarly, the nozzle 64 sprays hydraulic fluid against the lead-out line 38 in the second peripheral compartment 48. The sprayed hydraulic fluid then accumulates at the bottom of the first peripheral compartment 46 and the second peripheral compartment 48 so as to form a layer near the filter 50. The pump 76 draws the hydraulic fluid, which is then reintroduced under pressure into the tank 44.

[0050] Reference Figure 4 , schematically represents another embodiment of a cooling device 80 intended to be incorporated in an electric machine 2. Identical elements have the same reference numerals.

[0051] according to Figure 4 The cooling device 80 of the embodiment of the present invention differs from the cooling device 52 in that it includes a first output pipe 82 and a second output pipe 84 instead of the output pipe 66. The first output pipe 82 is connected to the filter 50 of the first peripheral compartment 46. The second output pipe 84 is connected to the filter 50 of the second peripheral compartment 48. The cooling device 80 includes a first pump 86 and a second pump 88 mounted on the first output pipe 82 and the second output pipe 84, respectively.

[0052] Cooling device 80 includes injection conduit 90. Injection conduit 90 includes a first upstream portion 92 connected to first pump 86 and a second upstream portion 94 connected to second pump 88. Injection conduit 90 includes a downstream portion 96 fluidly connected to tank 44 and first and second upstream portions 92, 94.

[0053] With this arrangement, the first pump 86 and the second pump 88 generate a flow of high pressure hydraulic fluid in the groove 44. This fluid is directed through the high pressure passage 54 into the first peripheral compartment 46 and the second peripheral compartment 48. In this way, the hydraulic fluid cools the stator 20 and the rotor 30, as shown in FIG. Figure 3 Next, the fluid contained in the first peripheral compartment 46 is collected by the filter 50, which is associated with the first outlet duct 82 by the suction of the first pump 86. Similarly, the fluid contained in the second peripheral compartment 48 is sucked by the second pump 88 via the second outlet duct 84 and is associated with the filter 50. The fluid sucked by the first pump 86 on the one hand and by the second pump 88 on the other hand follows the first upstream portion 92 and the second upstream portion 94, respectively, to re-enter the tank 44 via the downstream portion 96.

[0054] This embodiment makes it possible to implement the same Figure 3The cooling device 80 is therefore particularly suitable for electric machines for particularly demanding applications, such as electric machines intended to be incorporated in a drive train in an all-terrain vehicle or an aircraft.

[0055] In the example shown, the cooling device 80 has no check valve or equalization pipe. However, in order to limit the risk of pump failure and the risk of hydraulic fluid level imbalance to the greatest extent possible, it is possible to add check valves on the first output pipe 82 and the second output pipe 84 and / or add an equalization pipe connecting the first output pipe 82 and the second output pipe 84. Similarly, the drive module 79 and the temperature sensor 78 can of course be integrated in the cooling device 80 without departing from the scope of the present invention.

[0056] In view of the above, the electric machine 2 and the cooling devices 52 and 80 make it possible to effectively cool the electric machine by radially inserting the slots 44 between the housing 4 and the stator 20, while increasing compactness and limiting the risk of cooling failure when the vehicle is tilted sharply or the road has a large slope.

Claims

1. An electric machine (2) of a motor vehicle, comprising a cooling device (52, 80), the cooling device comprising a tank (44) and a circuit (53) fluidically connected to the tank (44), characterized in that The groove (44) is located radially relative to the axis (6) of the electric machine (2) between the housing (4) of the electric machine (2) and the stator (20) of the electric machine (2) and over the entire circumference around the axis (6) of the electric machine (2), the circuit (53) comprises a first peripheral compartment (46) axially offset relative to the groove (44), the cooling device (52, 80) comprises a first annular sealing device (40) at right angles to the axis (6) of the electric machine (2), the first annular sealing device (40) being axially inserted between the groove (44) and the first peripheral compartment (46), the circuit (53) comprising a second peripheral compartment (48), The groove (44) is axially inserted between the first peripheral compartment (46) and the second peripheral compartment (48), the cooling device (52, 80) comprises a second annular sealing device (42) at right angles to the axis (6) of the electric machine (2), the second annular sealing device (42) being axially inserted between the groove (44) and the second peripheral compartment (48), The first annular sealing device and the second annular sealing device include radial inner ends axially contacting the axial front end surface (22d) of the body (22) of the stator, The cooling device comprises a fluid level equalization pipe (71) fluidly connected to the first peripheral compartment (46) and the second peripheral compartment (48), the equalization pipe (71) comprising a nozzle (72) and a ball (73) disposed in the nozzle.

2. The electric machine (2) according to claim 1, wherein: The circuit (53) comprises a channel (54) which is fluidically connected to the groove (44); and an injection device (62) which is connected to the channel (54) and emerges in the first peripheral compartment (46), the injection device (62) being axially arranged to face the winding (24) of the rotor (30) of the electric machine (2).

3. The electric machine (2) according to claim 2, wherein: The circuit (53) includes a pump (76), an output pipe, and an injection pipe connecting the pump (76) to the tank (44), the output pipe including a first upstream portion fluidly connected to the first peripheral compartment (46), a second upstream portion fluidly connected to the second peripheral compartment (48), and a downstream portion (70) connecting the first upstream portion, the second upstream portion and the pump (76).

4. The electric machine (2) according to claim 2, wherein: The circuit (53) includes a first pump (86), a first output pipe fluidly connected to the first peripheral compartment (46), a second pump (88), a second output pipe fluidly connected to the second peripheral compartment (48), and an injection pipe, the injection pipe including a first upstream portion, a second upstream portion, and a downstream portion (96) connecting the first upstream portion, the second upstream portion and the tank (44), the first pump (86) connecting the first output pipe to the first upstream portion, and the second pump (88) connecting the second output pipe to the second upstream portion.

5. The electric machine (2) according to claim 3, wherein: The circuit (53) comprises a non-return valve (69) arranged on the output line.

6. The electric machine (2) according to claim 4, wherein: The circuit (53) comprises a check valve arranged on the first outlet pipe or the second outlet pipe.

7. An electric machine (2) according to any one of claims 1 to 4, wherein: The cooling device further comprises management means for managing the temperature of the hydraulic fluid contained in the tank (44), the management means being able to drive the supply means of the stator (20) of the electric machine (2).

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