ENGINE GROUP AND MOBILITY DEVICE COMPRISING SUCH AN ENGINE GROUP

Abstract

The motor group comprises: - an electric machine including a stator (104) and a rotor; - an inverter (110) for driving the stator (104); - an output shaft; - a gear system between the rotor and the output shaft; - a housing in which at least the stator (104) and the gear system extend, the housing containing oil (124) extending onto a bottom (126) of the housing (112), a wheel (118D) of the gear system, called the projection wheel, being designed to, during its rotation, drive and project the oil from the bottom (126) of the housing (112) onto an element to be cooled (116); - a retention basin (138) designed to receive the projected oil (124); and - a return path for the oil (124) overflowing from the retention basin (138) to the bottom (126) of the housing (112). The stator (104) and / or a heat sink (112) of the inverter (110) extend at least partially into the retention basin (138) to be immersed in the retained oil (124).Figure for the summary: Fig. 3.

Description

Title of the invention: ENGINE UNIT AND MOBILITY DEVICE COMPRISING SUCH AN ENGINE UNIT Technical field of the invention

[0001] The present invention relates to a motor unit and a mobility device comprising such a motor unit.

[0002] A mobility device is, for example, a motorized land vehicle, a train, an aircraft, or a drone. A motorized land vehicle is, for example, a car, a motorcycle, a motorized bicycle, or a motorized wheelchair. Technological background

[0003] The international PCT application published under number WO 2018 150128 A1 describes an engine unit comprising: - an electrical machine comprising a stator and a rotor; - a stator control inverter; - an output tree; - a gear system between the rotor and the output shaft; and - a housing containing at least the stator and the gear system extend, the casing containing oil extending over a bottom of the casing, a wheel of the gear system, called the projection wheel, being designed to, when rotating, drive and project the oil from the bottom of the casing onto the inverter's cooling fins.

[0004] Thus, the inverter is passively cooled, without requiring an oil circulation pump. However, this solution has the disadvantage that at low speeds of the electric machine, oil spray is less significant and may not be sufficient to effectively cool the inverter.

[0005] Furthermore, the international PCT application published under number WO 2022 201590 A1 proposes spraying oil onto the stator to cool it, and providing a retention basin to collect the sprayed oil. The retention basin is placed next to a rotor bearing, so that this bearing is immersed in the retained oil. This ensures that the bearing remains lubricated, even after the electric machine has not been used for a long period. However, this prior art does not provide a solution to the problem of cooling the inverter at low speeds of the electric machine.

[0006] It may therefore be desirable to provide an engine group which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0007] A motor group comprising: is therefore proposed. - an electrical machine comprising a stator and a rotor; - a stator control inverter; - an output tree; - a gear system between the rotor and the output shaft; - a housing containing at least the stator and the gear system extend, the casing containing oil extending onto the bottom of the casing; - a part, called the projection part, designed to be driven in rotation by the gear system and, during its rotation, to drive and project the oil from the bottom of the housing onto an element to be cooled; - a retention basin designed to receive the spilled oil; and - a return path for the oil overflowing from the retention basin towards the bottom of the casing; characterized in that the stator and / or a heat sink of the inverter extend at least partially into the retention basin to be immersed in the retained oil.

[0008] Thus, thanks to the invention, the stator and / or the inverter are always sufficiently cooled, even at low speed of the electric machine, thanks to the retained oil in which they are immersed.

[0009] The invention may further include one or more of the following optional features, according to any technically possible combination.

[0010] Optionally, the projection part is a wheel of the gear system, called a projection wheel, designed, when rotating, to drive and project the oil from the bottom of the housing onto the element to be cooled.

[0011] Optionally also, the projection wheel is the largest wheel in the gear system.

[0012] Optionally also, the heat sink includes a body against which the inverter is pressed and projections of the heat sink body, these projections being designed to bathe in the retained oil.

[0013] Optionally also, the heat sink projections include fins extending in a direction of oil projection so that the projected oil flows between the fins.

[0014] Optionally also, the element to be cooled includes the heat sink and / or the stator.

[0015] Optionally also, at least part of the stator is on the return path so that the oil overflowing from the retention basin flows onto the stator.

[0016] Optionally, the engine assembly also includes, on the return path, a device for limiting the flow of oil onto the stator, comprising: - a buffer basin designed to receive the oil overflowing from the retention basin; and - pipes placed in the bottom of the buffer tank and designed to carry the oil from the buffer tank to the stator.

[0017] Optionally, the gear system is also a reducer.

[0018] A mobility device comprising: is also proposed. - a propulsion system, comprising, for example, one or more drive wheels; and a motor group according to the invention, used as a powertrain for driving the movement system. Brief description of the figures

[0019] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: - [Fig. 1] is an exploded view of an example of an engine group in which the invention is implemented, - [Fig. 2] is a cross-sectional view of the engine assembly of [Fig. 1], and - [Fig.3] is another cross-sectional view of the engine group of [Fig.1]. Detailed description of the invention

[0020] With reference to [Fig.1], an example of a motor group 100 in which the invention is implemented will now be described.

[0021] The engine unit 100 is, for example, designed to equip a mobility device comprising a propulsion system, for example one or more drive wheels. The engine unit 100 can then be used as a powertrain for driving the propulsion system.

[0022] Thus, the motor group 100 comprises, firstly, an electric machine 102 equipped with a stator 104 and a rotor 106 movable relative to the stator around a motor shaft AM. The electric machine 102 is designed to operate as a motor and / or a generator. The electric machine 102 further comprises a motor shaft 108 extending along the motor shaft AM and fixed to the rotor 106 to rotate with it.

[0023] The motor group 100 further includes an inverter 110 for driving the stator 104. More specifically, the inverter 110 is designed to drive the stator 104 so that the latter generates a rotating magnetic field, under the effect of which the rotor 106 is designed to rotate around the axis of rotation AM.

[0024] To cool the inverter 110, the motor assembly 100 further comprises a heat sink 112 having a body 114 against which the inverter 110 is pressed, and projections 116 projecting from the body 114 of the heat sink 112. These projections 116 may be pins or fins. In the latter case, the fins preferably extend in a direction of projection of the oil 124, as in the illustrated example, so that the projected oil 124 flows between the fins and dissipates heat more effectively.

[0025] The motor group 100 further comprises a gear system 118 coupled to the rotor 106 in order to be driven by the latter. The gear system 118 comprises successive gears 118A-D meshing with each other, the first gear 118A in the sequence being, for example, fixed to the motor shaft 108. For example, the gear system 118 is a reduction gear, so that the last gear 118D in the sequence rotates at a lower speed, for example at least 5 times lower, for example at least 8 times lower, for example at least 10 times lower, than that of the first gear 118A in the sequence.

[0026] The drive unit 100 further comprises an output shaft 120 designed to be coupled to the gear system 118, and more specifically to the last wheel 118D of the gear system 118, in order to drive the movement system of the mobility device. For example, the output shaft 120 is fixed to the last wheel 118D so as to rotate with it.

[0027] The motor assembly 100 further comprises a housing 122 in which at least the stator 104 and the gear system 110 extend. The housing 122 is designed to contain oil 124 extending over a bottom 126 of the housing 122.

[0028] For example, the housing 122 has an upper cover 122A in which the inverter 110 extends and which has a lower opening 128 closed by the body 114 of the heat sink 112. The housing 122 further has a lower basin 122B having a first compartment 130 for receiving the electric machine 102 and a second compartment 132 for receiving the gear system 118. These two compartments 130, 132 communicate with each other. The basin 122B also has an upper opening 134 leading to the first compartment 130.

[0029] A wheel of the gear system 110, called the projection wheel, is designed, during its rotation, to drive and project the oil 124 from the bottom 126 of the housing 122. Preferably, this is the largest wheel of the gear system 118. Indeed, the largest wheel is generally the one that is always immersed in the oil 124 from the bottom 126 of the housing 122. This is wheel 118D in the illustrated example. To facilitate the drive of the oil 124, the housing 122, and in particular the tank 122B, has a curved wall 136 following the curvature of the projection wheel 118D.

[0030] The oil 124 is for example sprayed onto the cooling fins 116. For this, as in the illustrated example, the spray wheel 118D is designed to spray the oil 124 into the upper opening of the tank 122 where the cooling fins 116 extend. In this case, the curved wall 136 preferably extends from the bottom 126 to the upper opening 134 of the tank 122B.

[0031] The drive unit 100 further includes a retention basin 138 designed to receive the sprayed oil 124. For example, as in the illustrated example, the drive unit 100 includes a tank 140, at least part of which forms the retention basin 138. The tank 140 extends into the upper opening 134 of the tank 122B. The cooling fins 116 of the inverter 110 then extend, at least partially, into the retention basin 138 to be immersed in the retained oil 124. The retention basin 138 has no bottom outlet to allow the oil 124 to accumulate. Discharge occurs at a certain height, either by overflowing over a wall of the retention basin 138 (as in the illustrated example) or through an opening in a wall of the retention basin 138.

[0032] The engine group 100 includes a return path 142 for the oil 124 overflowing from the retention basin 138, towards the bottom 114 of the housing 112.

[0033] Preferably, as in the illustrated example, at least part of the stator 104 is located on the return path 142, for example under the retention basin 138, to receive the oil 124 overflowing from the retention basin 138.

[0034] With reference to [Fig. 2], the motor assembly 100 further includes, on the return path 142, a flow-limiting device 202 for restricting the flow of oil onto the stator 104. This flow-limiting device 202 includes a buffer basin 204 designed to receive the oil 124 overflowing from the retention basin 138. The flow-limiting device 202 further includes conduits 206 (in [Fig. 2], for clarity only some are identified by the reference numeral 206), formed in a base 208 of the buffer basin 204 and designed to conduct the oil 124 from the buffer basin 204 to the stator 104. Thus, it is possible to limit the flow of oil 124 reaching the rotor 104, while ensuring that the oil 124 is properly distributed over the stator. 104.

[0035] With reference to [Fig. 3], during operation, the rotor 106 rotates, causing the projection wheel 118D to rotate. The latter is in contact with the oil 124 present at the bottom 126 of the housing 112 and, by virtue of its rotation, carries and lifts the oil 124, projecting it onto the cooling fins 116 to cool the inverter 110. The projected oil 124 then falls back into the retention basin 138 where it accumulates, so that the cooling fins 116 are immersed in the accumulated oil 124. When the accumulated oil 124 reaches a certain level (that of [Fig. 2]), it overflows from the retention basin 138 to flow into the basin The oil 124 exits the reservoir 204 through the conduits 206 to reach the stator 104. The flow rate of the oil 124 is limited by the conduits 206. Thus, when the oil 124 is sprayed onto the cooling fins 116, the reservoir tends to fill, while when the spray is weak, the reservoir tends to empty. This ensures a relatively constant flow of oil 124 onto the stator 104, regardless of the level of oil spray and therefore the speed of the electric machine 102. The oil 124 passing over the stator 104 then enters compartment 132 of the gear system 118, since compartments 130 and 132 are interconnected, before returning to the bottom 126 of the housing 112.

[0036] In conclusion, it is clear that a motor unit such as the one described above makes it possible to remove heat from the cooling fins, without requiring a pump and even when the electric machine is running at low speed.

[0037] It should also be noted that the invention is not limited to the embodiments described above. It will indeed be apparent to those skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.

[0038] In particular, the retention basin could be located below the stator, so that the stator is immersed in the oil accumulated in the retention basin. It could even be envisaged that the inverter be placed lower so that both the heat sink and the stator are immersed in the oil accumulated in the retention basin. Furthermore, the element cooled by the oil spray could be the stator, instead of or in addition to the heat sink, or even a different element altogether.

[0039] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted as including all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

1. Demands Engine group (100) comprising: - an electrical machine (102) comprising a stator (104) and a rotor (106); - an inverter (110) for driving the stator (104); - an output tree (120); - a gear system (118) between the rotor (106) and the output shaft (120); - a housing (112) in which at least the stator (104) and the gear system (118) extend, the housing (112) containing oil (124) extending over a bottom (126) of the housing (112); - a part (118D), called a projection part, designed to be driven in rotation by the gear system (118) and, during its rotation, to drive and project the oil (124) from the bottom (126) of the housing (112) onto an element to be cooled; - a retention basin (138) designed to receive the sprayed oil (124); - a return path (142) for the oil (124) overflowing from the retention basin (138) to the bottom (126) of the housing (112), at least a portion of the stator (104) being located on the return path (142) so that the oil (124) overflowing from the retention basin (138) flows over the stator (104); and - on the return path (142), a device (202) for limiting the flow rate of oil (124) on the stator (104), comprising: • a buffer basin (204) designed to receive the oil (124) overflowing from the retention basin (138); and • pipes (206) provided in a bottom (208) of the buffer basin (204) and designed to conduct the oil (124) from the buffer basin (204) to the stator (104); characterized in that the stator (104) and / or a heat sink (112) of the inverter (110) extend at least partly into the retention basin (138) to be immersed in the retained oil (124).

2. Motor unit (100) according to claim 1, wherein the projection part is a wheel (118D) of the gear system (118), called the projection wheel, designed, when rotating, to drive and project the oil (124) from the bottom (126) of the housing (112) onto the element to be cooled.

3. Motor unit (100) according to claim 2, wherein the projection wheel (118D) is the largest wheel of the gear system (118).

4. Engine assembly (100) according to any one of claims 1 to 3, wherein the heat sink (112) comprises a body (114) against which the inverter (110) is pressed and projections (116) of the body (114) of the heat sink (112), these projections (116) being designed to bathe in the retained oil (124).

5. Engine assembly (100) according to claim 4, wherein the projections (116) of the heat sink (112) have fins extending in a direction of projection of the oil (124) so ​​that the projected oil (124) flows between the fins.

6. Motor assembly (100) according to any one of claims 1 to 5, wherein the element to be cooled comprises the heat sink (112) and / or the stator (104).

7. Motor unit (100) according to any one of claims 1 to 6, wherein the gear system (118) is a reducer.

8. Mobility device comprising: - a movement system, comprising for example one or more drive wheels; and - a motor unit (100) according to any one of claims 1 to 7, used as a drive power unit for the movement system.

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