ELECTRIC MOTORIZATION DEVICE INCORPORATING AN ELECTRICALLY INSULATING HEAT SINK

An electric motorization device including an electric motor, an electronic system comprising power electronic elements, and a heat sink that is intended to cool the electronic system. The heat sink comprises a first shell configured to allow heat exchange between a coolant fluid and the electronic system, and a second shell configured to prevent heat exchange between the coolant fluid and the electric motor. The first shell and the second shell together define a cavity configured to allow the passage of the coolant fluid. The first shell and the second shell are each made of a material configured to ensure electrical insulation, in particular between the electronic system, the coolant fluid and the electric motor.

TECHNICAL FIELD

The present invention relates to an electric motorization device comprising an electric motor.

BACKGROUND

In general, the current electric motors include a rotor secured to a shaft and a stator which surrounds the rotor. The stator is mounted in a casing which includes bearings for the rotational mounting of the shaft. The rotor includes a body formed by a bundle of laminations or polar wheels (claw pole) held in the form of a stack by means of a suitable fastening system. The body of the rotor includes internal cavities housing permanent magnets. The stator includes a body consisting of a bundle of laminations forming a crown, the inner face of which is provided with teeth delimiting two by two a plurality of slots open towards the inside of the stator body and intended to receive phase windings.

The electric motors being likely to be damaged or even destroyed in the event of overheating of the rotor, it is generally necessary to equip electric motors with a cooling system to lower the general temperature of the motor, and in particular when it overheats.

Furthermore, the supply of the electric motor and its driving require the integration of an electronic system. Generally, these electronic systems comprise a regulator making it possible to vary the intensity of the current, and a power converter such as an inverter, making it possible to transform a direct current into alternating current. However, depending on the type of electric motor used and depending on the electronic components used in the electronic system, the on-board voltages used may be different. Thus, during assembly of the electric motor and its operation, malfunctions may occur if the masses of the various systems are not isolated. Furthermore, to obtain a long-lasting and optimal operation of the electric motorization device, it is important to also guarantee cooling of the electronic system.

It is known to use glycol water in the cooling circuit of the electric motor, and/or to use an aluminum heat sink. This solution is satisfactory in that it allows the motor to be cooled. However, glycol water has electrical conductivity, so it is not possible to integrate the electronic system.

BRIEF SUMMARY

The purpose of the present invention is to propose a solution which responds to all or part of the aforementioned problems:

This goal may be achieved through the implementation of an electric motorization device comprising:an electric motor comprising a rotor intended to be set in motion, a stator, and a cooling chamber configured to cool the electric motor;an electronic system comprising power electronic elements, said power electronic elements being configured to drive the electric motor;a heat sink interposed between the electric motor and the electronic system, said heat sink being intended to cool the electronic system and comprising:a first shell intended to cooperate with the electronic system, and configured to allow a heat exchange between a cooling fluid and the electronic system;a second shell intended to cooperate with the electric motor on the one hand and with the first shell on the other hand, said second shell being configured to prevent a heat exchange between the cooling fluid and the electric motor.

The first shell and the second shell defining between them a cavity, said cavity being configured to allow the passage of the cooling fluid.

The first shell and the second shell are each constituted of a material configured to guarantee an electrical insulation, in particular between the electronic system, the cooling fluid and the electric motor.

The provisions previously described make it possible to guarantee electrical insulation between the power electronic elements of a vehicle (with electric motorization, hybrid or originating from a fuel cell) which may comprise an inverter, and the electric motor. In this way, the masses of the different electric systems are isolated from each other, and the overvoltages between each network of different voltages are avoided. Furthermore, the passage of the cooling fluid in the cavity makes it possible to cool the electronic system.

The electric motorization device may also have one or more of the following characteristics, taken alone or in combination.

According to one embodiment, the first shell is formed of a composite material configured to be electrically insulating and thermally conductive, said composite material comprising thermally conductive fillers of the group comprising aluminum oxides, aluminosilicates, aluminum or magnesium hydroxides, boron nitrides.

According to one embodiment, the second shell is formed of an electrically insulating and thermally insulating plastic material, for example belonging to the group comprising polyolefins, styrene materials, polyamides, poly(phenylene sulphide), polysulphones and composites reinforced with non-conductive mineral fillers such as fiberglass.

According to one embodiment, the heat sink comprises at least one fluid inlet which is fluidly connected with the cavity, said at least one fluid inlet being configured to allow the entry of the cooling fluid into the cavity; and at least one fluid outlet which is fluidly connected with the cavity on the one hand and with the cooling chamber on the other hand, and intended to allow the passage of the cooling fluid from the cavity to the cooling chamber.

According to one embodiment, the fluid outlet is fluidly connected with a general glycol circuit of the vehicle, in particular in the case where the electronic system is separate from the electric motor.

The provisions previously described make it possible to have a cooling circuit common between the electric motor and the electronic system.

According to one embodiment, the fluid inlet comprises a tube configured to cooperate with an inlet orifice, made in the second shell, said inlet orifice being configured to ensure a fluid connection between the tube and the cavity.

According to one embodiment, the heat sink comprises at least one wall secured to the first shell and/or to the second shell, said at least one wall projecting into the cavity and being configured to direct the passage of the cooling fluid into the cavity.

According to one embodiment, the at least one wall is configured to define a circuit for the passage of the cooling fluid in the cavity.

According to one embodiment, the at least one wall has at least one wall section having a curved shape.

According to one embodiment, the heat sink comprises a plurality of walls providing a heat exchange surface between the cooling fluid and the material constituting the plurality of walls.

In this way, the circuit for the passage of the cooling fluid makes it possible to cool more effectively the first shell by increasing the heat exchange surface.

According to one embodiment, the electric motor is configured to operate at a voltage substantially equal to 48V.

According to one embodiment, the electronic system is configured to operate at a voltage substantially equal to 12V.

According to another embodiment, the electronic system is configured to operate at a voltage substantially equal to 24V.

According to another embodiment, the electronic system is configured to operate at a voltage of between 12V and 52V.

The power electronic elements may in particular comprise one or more elements included in the group comprising an inverter, a rectifier, a voltage step-up, or a voltage step-down. Furthermore, the electronic system may comprise transistors (Mosfet, IGBT) configured to drive the electric motor by allowing the passage or alternatively the suppression of the currents in the stator windings.

According to one embodiment, the first shell comprises first fastening means intended to make it possible to secure the electronic system to the first shell.

According to one embodiment, the first shell comprises non-opening threaded holes so that the electronic system is screwed onto the first shell.

According to one embodiment, the first shell and the second shell comprise second fastening means configured to secure said first shell to said second shell.

According to one embodiment, the first shell may be fastened to the second shell by gluing, by screwing, by welding or by clipping.

According to one embodiment, the first shell has a shape adapted to cooperate with the electronic system.

According to one embodiment, the first shell comprises a plate, for example having the shape of a disc, configured to allow the fastening of the electronic system onto the plate.

According to one embodiment, all or part of the electronic system may be screwed, glued, welded or printed on the first shell.

According to one embodiment, the second shell has a shape adapted to the electric motor.

In general, the electric motors have a cylindrical shape. In this case, the second shell may have a cylindrical shape to interfit and cooperate with the electric motor.

DETAILED DESCRIPTION

In the figures and in the remainder of the description, the same references represent identical or similar elements. In addition, the various elements are not shown to scale so as to favor the clarity of the figures. Furthermore, the different embodiments and variants are not mutually exclusive and may be combined with one another.

As illustrated inFIG.1, the invention relates to an electric motorization device1comprising an electronic system20, an electric motor30, and a heat sink40.

The electric motor30comprises a rotor10intended to be set in motion, a stator36and a cooling chamber38disposed on the periphery of the rotor1and configured to cool the electric motor30. This electric motor30comprises in particular a casing in two parts housing the rotor10secured in rotation to a rotor shaft12and an annular stator36which surrounds the rotor10coaxially with the rotor shaft12. The casing consists in particular of a front bearing32and a rear bearing34connected to each other for example by means of screws. The bearings32,34are hollow-shaped and each generally centrally carry a bearing, for example ball bearings33, for the rotational mounting of the rotor shaft12.

As illustrated inFIG.1, winding heads37project axially on either side of the stator body36and are housed in the intermediate space separating the stator36from the respective bearings32,34.

In general, the electric motor30is configured to operate at a voltage substantially equal to 48V.

The electronic system20may comprise power electronic elements, said power electronic elements being configured to drive the electric motor30.

The power electronic elements may in particular comprise one or more elements included in the group consisting of an inverter, a rectifier, a voltage step-down or step-up. Furthermore, the electronic system20may comprise transistors (Mosfet, IGBT) configured to drive the electric motor30by allowing the passage or alternatively the suppression of the currents in the stator windings.

Depending on the vehicle on which the electric motorization device1is installed, the electronic system20may be configured to operate at a voltage substantially equal to 12V, or at a voltage substantially equal to 24V, or at a voltage of between 12V and 52V.

The heat sink40is interposed between the electric motor30and the electronic system20.

The heat sink40may be intended to cool the electronic system20and/or the electric motor30.

According to the embodiment shown inFIG.1, the heat sink40comprises at least one fluid inlet45configured to allow the entry of the cooling fluid into a cavity48included in the heat sink40; and at least one fluid outlet47which is fluidly connected with the cavity48on the one hand and with the cooling chamber38on the other hand. In this way a cooling fluid may circulate from the cavity48to the cooling chamber38.

The provisions described make it possible to have a cooling circuit common between the electric motor30and the electronic system20.

Referring toFIGS.2to5, the heat sink40comprises a first shell42intended to cooperate with the electronic system20, and a second shell44intended to cooperate with the electric motor30on the one hand and with the first shell42on the other hand. The first shell42and the second shell44define between them a cavity48configured to allow the passage of the cooling fluid.

Advantageously, the first shell42and the second shell44are each made of a material guaranteeing electrical insulation, in particular between the electronic system20, the cooling fluid and the electric motor30.

Furthermore, the first shell42may be configured to allow a heat exchange between the cooling fluid and the electronic system20, and the second shell44can be configured to prevent a heat exchange between the cooling fluid and the electric motor30.

In other words, the first shell42may be made of a composite material configured to be electrically insulating and thermally conductive, said composite material comprising thermally conductive fillers belonging to the group consisting of aluminum oxides, aluminosilicates, aluminum or magnesium hydroxides, boron nitrides, and the second shell44may be made of a electrically insulating and thermally insulating plastic or composite material belonging to the group comprising polyolefins (polyethylene, polypropylene, etc.), styrene materials (polystyrene, acrylonitrile butadiene styrene etc.), polyamides (PA6, PA66, polyphthalamide, etc.), poly(phenylene sulphide), polysulfones (polyethersulfone, polysulfone, etc.), and composites reinforced with non-conductive mineral fillers such as fiberglass.

The first shell42may comprise first fastening means intended to secure the electronic system20to the first shell42. For example, the first shell42may be fastened to the electronic system20by an adhesive. The first shell42also comprises a plate, for example having the shape of a disk, configured to allow the fastening of the electronic system20onto the plate.

The first shell42and the second shell44may be provided with second fastening means configured to secure said first shell42to said second shell44. For example, the first shell42may be fastened to the second shell44by gluing, by screwing, by welding or by clipping.

In general, the electric motors have a cylindrical shape. Thus, the second shell44has a shape adapted to the electric motor30. For example, the second shell44may have a cylindrical shape to interfit and cooperate with the electric motor30.

According to a non-limiting variant shown inFIGS.2to6, the second shell44comprises the fluid inlet45and the fluid outlet47. The fluid inlet45may have a tube configured to cooperate with an inlet orifice made in the second shell44. The inlet orifice being configured to ensure a fluid connection between the tube and the cavity48. In this way, the fluid inlet45is fluidly connected with the cavity48.

Advantageously, the heat sink40may comprise at least one wall46secured to the first shell42and/or to the second shell44. According to the embodiment illustrated inFIG.6, the heat sink comprises a plurality of walls46included on the second shell44and projecting into the cavity48. Each wall46of the plurality of walls46has at least one wall section46having a curved shape, so as to direct the passage of the cooling fluid into the cavity48.

The provisions previously described allow the walls46to define a circuit for the passage of the cooling fluid in the cavity48and provide a larger heat exchange surface between the cooling fluid and the material constituting the plurality of walls46.

In this way, the circuit for the passage of the cooling fluid makes it possible to cool more effectively the first shell42by increasing the heat exchange surface.