EP4326569A1

EP4326569A1 - A cooling system for an integrated drivetrain assembly and an integrated power electronics assembly and an electrified vehicle

Info

Publication number: EP4326569A1
Application number: EP22731981.1A
Authority: EP
Inventors: Yejin JIN; Kai Chen; Guoqiang Sun
Original assignee: Valeo Powertrain Nanjing Co Ltd
Current assignee: Valeo Powertrain Nanjing Co Ltd
Priority date: 2021-04-19
Filing date: 2022-04-19
Publication date: 2024-02-28
Also published as: CN115214349A; WO2022222909A1

Abstract

The present disclosure relates to a cooling system for an integrated drivetrain assembly and an integrated power electronics assembly of an electrified vehicle. The integrated drivetrain assembly comprises an electric motor, a reducer mechanically coupled to the electric motor, and a power inverter electrically connected to the electric motor and the integrated power electronics assembly. The cooling system comprises one cooling circuit configured for being flowed through with a liquid coolant and for distributing the liquid coolant throughout the integrated drivetrain assembly and the integrated power electronics assembly so as to cool down all the components in the two assemblies. The present disclosure also relates to an electrified vehicle comprising cooing system according to the above described is provided.

Description

A COOLING SYSTEM FOR AN INTEGRATED DRIVETRAIN ASSEMBLY AND AN INTEGRATED POWER ELECTRONICS ASSEMBLY AND AN ELECTRIFIED VEHICLE

FIELD OF THE INVENTION

Embodiments of the present disclosure relate generally to a cooling system for an integrated drivetrain assembly and an integrated power electronics assembly of an electrified vehicle and an electrified vehicle comprising the cooling system.

BACKGROUND OF THE INVENTION

The trend towards designing and building fuel efficient, low emission vehicles has increased dramatically, this trend driven by concerns over the environment as well as increasing fuel costs. At the forefront of this trend has been the development of electrified vehicles, such as BEV, HEV, PHEV, Range extended EV, Fuel Cell etc., electrified vehicles that combine a relatively efficient combustion engine with an electric drive motor. Electrified vehicles can include components, particularly the drivetrain system, that generate heat. Excessive heat build-up can cause performance degradation or damage to the components. Specially, cooling solutions for high power electrified vehicles, e.g., for BEV whose power is larger than 30kW, especially cooling for power electronics assembly, such as On-board Charger ( “OBC” ) , DC/DC converter and Power Distribution Unit ( “PDU” ) and for different components in the drivetrain system would be more complex and the cost would be high.
Therefore, it would be desirable if any improvements on cooling design for the drivetrain system for electrified vehicles could be provided at least with simple configuration, high efficiency and low cost.
SUMMARY OF THE INVENTION
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In accordance with one aspect disclosed herein, a cooling system for an integrated drivetrain assembly and an integrated power electronics assembly of an electrified vehicle is provided. The integrated drivetrain assembly generally comprises an electric motor, a reducer mechanically coupled to the electric motor, and a power inverter electrically connected to the electric motor and the integrated power electronics assembly. The cooling system comprises one cooling circuit configured for being flowed through with a liquid coolant and for distributing the liquid coolant throughout the integrated drivetrain assembly and the integrated power electronics assembly so as to cool down all the component in the two assemblies.
In accordance with another aspect disclosed herein, an electrified vehicle comprising the cooling system according to the above described is provided.
These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following detailed description. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
FIG. 1 is a schematic view of a cooling system for an integrated drivetrain assembly and an integrated power electronics assembly in accordance with an exemplary aspect of the present disclosure;
FIG. 2 is a schematic view of a cooling system for an integrated drivetrain assembly and an integrated power electronics assembly in accordance with another exemplary aspect of the present disclosure;
FIG. 3 is a schematic view of a cooling circuit of the cooling system within the integrated drivetrain assembly in accordance with an exemplary aspect of the present disclosure;
FIGs 4A and 4B are schematic views of a heatsink cover of the power inverter in accordance with an exemplary aspect of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made to in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “a” , “an” and “the” are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. The terms “comprising” , “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The terms “first” and “second” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of individual components.
Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures, FIG. 1 shows a cooling system 100 for an integrated drivetrain assembly 10 and an integrated power electronics assembly 20 in accordance with one embodiment of the present disclosure. The drivetrain assembly 10 is generally integrated with a power inverter 11, an electric motor 12 and a reducer 13. The drivetrain assembly 10 as shown is therefore a single unit.
The electric motor 12 can be a synchronous motor or an asynchronous motor. When it is a synchronous motor, it may include a wound rotor or a permanent magnet rotor. The peak power supplied by the electric motor can be between 10KW and 80KW, for example, of the order of 40KW, for a nominal supply voltage of 48V to 400V, or up to 800V for higher power. In the case of an electric motor adapted to a high voltage supply, the nominal power supplied by this electric motor may be 25KW. In the illustrated embodiment, the electric motor 12 is a synchronous motor with permanent magnets, providing a peak power between 10KW and 80KW. The electric motor 12 can include a stator with a three-phase winding, or a combination of two three-phase windings or five-phase windings.
The reducer 13 is mechanically coupled to the electric motor 12. The reducer 13 can transform the electric motor’s high speed, low torque to low speed, high torque. The reducer 13 may comprise two or more gears, with one of the gears driven by the electric motor 12 for instance, for torque increase via speed reduction. The reducer may further comprise a transmission shaft, i.e., an intermediate shaft, linking a driving gear driven by one transmission shaft of the electric motor 12 and another gear of larger diameter coupled to a driven mechanical load (not shown, e.g., vehicle wheel shafts) .
In the illustrated embodiments, the electric motor 12 and the reducer 13 are designed with high thermal capacity. The power inverter 11 is attached by the electrical wires to the electric motor 12 and mechanically to a wall of the electric motor 12 or to a wall of the reducer 13 or to both walls of the electric motor 12 and the reducer 13. The power inverter 11 converts the direct current ( “DC” ) supplied by the integrated power electronics assembly 20 providing with the electric energy of a nominal voltage to the alternating current ( “AC” ) used to the electric motor 12. The power inverter 11 can comprise at least one power switching device (not shown) , such as, field effect transistors ( “FETs” ) , metal oxide semiconductor field effect transistors ( “MOSFETs” ) or insulated gate bipolar transistors ( “IGBTs” ) . In the case of a nominal supply voltage of 48V, the power switching device can be MOSFET transistors. In the case of a supply voltage corresponding to a high voltage, the power switching device can be IGBTs.
Referring to FIG. 1, the integrated power electronics assembly 20 may comprise OBC, and/or DC/DC converter and/or PDU. OBC is generally installed in the BEV and connect to an external power supply. DC/DC converter is a power electronic device that convert the DC input voltage supplied by, e.g., the battery power, to a certain amplitude DC output voltage, which can be applied for all kinds of electrified vehicle, including for BEV. PDU is a high-voltage power supply that distributes the battery power to the high-voltage components of the vehicle. The integrated power electronics assembly 20 is electrically connected with the power inverter 11 and mechanically mounted to the power inverter 11, as illustrated in FIG. 1. In one embodiment, the integrated power electronics assembly 20 can be coupled with the integrated drivetrain assembly 10 by tubes 40, as illustrated in FIG. 2.
A cooling system is designed to ensure the temperatures of the integrated drivetrain assembly 10 and the integrated power electronics assembly 20 are maintained with a desired operating ranges when the vehicle is running and at stop, i.e., at a parking phase.
Referring to FIGs 1 to 2, the cooling system 100, 100’ may include a fan 130 equipped with a condenser 120. The fan 130 may provide with air flow towards the integrated drivetrain assembly 10 and the integrated power electronics assembly 20 to achieve a desired cooling by convection. In other case, the air cooling flow is provided either by the vehicle speed during running, or by natural cooling air flow at stop.
The cooling system 100, 100’ may also include a plurality of first cooling fins 140 arranged on an outer surface of a housing 14 containing at least the electric motor 12 and the reducer 13.
Referring to FIGs 1 to 2, the electric motor 12 and the reducer 13 are contained in the one-piece housing 14. A plurality of cooling fins 140 may be provided for the heat dissipation towards the outside of the integrated drivetrain assembly 10. The first cooling fins 140 may be carried by the outer surface of the housing 14. These cooling fins 140 are for example made in one piece with the housing 14. These cooling fins 140 allow to increase the outer surface of the housing, and thus promote the heat dissipation to the outside of the drivetrain assembly 10 via the housing. The entire outer surface of the housing 14 may carry cooling fins 140. The cooling fins 140 may be arranged in rows, and a pitch, constant or not, may exist between two adjacent rows. These rows may or may not all have the same orientation.
The cooling system 100, 100’ may further include a cooling circuit 110, 110’. The cooling circuit 110, 110’ being flowed through with coolant is provided for distributing the coolant throughout the integrated drivetrain assembly 10 and the integrated power electronics assembly 20.
The coolant can be the oil with ultra-low viscosity. The kinetic viscosity value of this kind of ultra-low viscosity oil at 40℃ will be less than 40 and the kinetic viscosity value at 100℃ will be less than 10. By using this kind of ultra-low viscosity oil flowing throughout the two assemblies via the cooling circuit 110, all components contained could be both lubricated and cooled down more efficiently with lower pressure drop.
The oil flowing in the cooling circuit 110, 110’ maybe transferred by a pumping device. The pumping device may control the oil flowing through the cooling circuit 110, 110’ at a required flow rate, further, may have the oil autonomously flow throughout the cooling circuit 110, 110’ for cooling and lubrication during operating, and may circulate the oil through the cooling circuit 110, 110’ as well. In one embodiment, the pumping device can be an electrical pump and the OBC of the integrated power electronics assembly 20 may supply power to the electrical pump for operation. In one embodiment, if the OBC is absent from the integrated power electronics assembly 20, a mechanical pump can be considered to apply in the cooling system.
The pumping device, as illustrated in FIGs 1 to 2, is an electrical pump 30 which is equipped with the integrated drivetrain assembly 10, particularly is fluidly in communication with an oil reservoir 113 as shown in FIG. 3 at a lower portion of the reducer 13 of the integrated drivetrain assembly 10. The electrical pump 30 will continue to work during the parking phase. During the operation of the electrical pump 30, the oil is pumped from the integrated drivetrain assembly 10 into the integrated power electronics assembly 20, then the oil flows back to the integrated drivetrain assembly 10. Further, in case of the mechanical pump can be driven by a driving shaft, such as an intermedia shaft, which will work when the vehicle wheel are rotating.
Generally, the oil is firstly transferred from electrical pump 30 to the power inverter 11, then into the integrated power electronics assembly 20 by at least tubes inside the integrated drivetrain assembly 10. As shown in FIG. 2, the oil is transferred into the integrated power electronics assembly 20 by tubes 40 outside of the two assemblies in addition to the tubes inside the integrated drivetrain assembly 10. The components, such as DC/DC converter (if any) , OBC (if any) , and PDU (if any) can be cooled down by the oil circuit within the integrated power electronics assembly 20.
Regarding the cooling for the power inverter 11, referring to FIGs 4A to 4B, the cooling circuit 110, 110’ can comprise a fluid turbulent passage 115 provided by the power inverter 11. The fluid turbulent passage 115 is particularly formed by a plurality of cooling spikes 116 arranged onto an inner surface 151 of a heatsink cover 15 for cooling the power switching device, such as IGBTs provided by the power inverter 11. The cooling spikes 116 are made of thermal material, for example aluminum. In one embodiment, the spikes 116 can be full of the fluid turbulent passage 115 with a high density so that the gap between the spikes 116 can be narrowed which will increase the flow velocity around the spikes 116, creating turbulence and local increase of flow velocity that will increase the cooling performance of the power switching device, such as IGBTs. The power switching device, such as IGBTs of the power inverter 11 is in direct contact with the oil flowing within the fluid turbulent passage 115 so that the heat dissipation thermal resistance can be improved. A plurality of second cooling fins 117 can be further arranged onto an outer surface 152 of the heatsink cover 15 for heat dissipation by convection. Ambient air, as well as the air from the fan 130, may flow through these cooling fins 117 to achieve a desired cooling.
The oil is then transferred into a housing 14 containing the electric motor 12 and the reducer 13. Referring to FIG. 3, the oil is transferred via tubes 50 inside the housing 14, in one embodiment, nozzles 51 may be provided by the tubes 50 for spraying the oil onto the inner wall of the housing 14, and onto the rotating components, such as gears, bearings, of the electric motor 12 and the reducer 13 for active lubrication and heat dissipation before the oil reaches the inner wall of the housing. In one embodiment, dedicated cooling channels 52 may be further provided for the oil to flow through the stator body, stator windings and the rotor of the electric motor 12, as well as the power electronics components. As shown in FIG. 3, several radial cooling channels can be arranged between the rotor and the stator so as to transfer the oil from the rotor to the stator. An annular cooling channel can be arranged around the outer surface of the stator and be fluidly in communication with the radial cooling channels so that the oil may be distributed to the outer peripheral surface of the stator. Furthermore, several axial cooling channels can be provided to be fluidly in communication with the annular cooling channel so as to have the oil flow through the outer peripheral surface of the stator. The electric motor 12 can be further cooled down via the dedicated cooling channels 52 by directly contacting with the oil.
Still referring to FIG. 3, the cooling circuit 110, 110’ can comprise an oil reservoir 113 provided by a lower portion of the reducer 13 for receiving the oil droplets from the nozzles 51 and the oil outputs from the dedicated cooling channels 52 and retaining the oil. In the meanwhile, the oil in the reservoir 13 allow gears of the reducer 13 to carry it to splash towards the housing 14 as well as the adjacent components which needs to be cooled down during the operation of the gears. The oil reservoir is also to be used for keeping necessary oil therein, which can ensure a minimum flow of the oil for cooling and lubricating inside the drivetrain assembly 10.
With such configuration, the integrated power electronics assembly and the integrated drivetrain assembly, including at least DC/DC converter, the power inverter 11, electric motor 12 and the reducer 13, can be cooled down by one continuously oil circuit, while driving or at parking. Furthermore, the heatsink cover of the power inverter is provided with two sides cooling fins, i.e., one for turbulence creation of the oil circuit, the other for the air cooling, which introduces air cooling for further improving the heat dissipation. Moreover, the arrangement of the fan and the condenser may ensure sufficient air flow for the air cooling.
This written description uses examples to disclose the embodiments of the present disclosure, including the best mode, and also to enable any person skilled in the art to practice embodiments of the present disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the embodiments described herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

A cooling system (100, 100’) for an integrated drivetrain assembly (10) and an integrated power electronics assembly (20) of an electrified vehicle, the integrated drivetrain assembly (10) comprising an electric motor (12) , a reducer (13) mechanically coupled to the electric motor, and a power inverter (11) electrically connected to the electric motor (12) and the integrated power electronics assembly (20) , the cooling system comprising:

one cooling circuit (110, 110’) configured for being flowed through with a coolant and for distributing the coolant throughout the integrated drivetrain assembly (10) and the integrated power electronics assembly (20) so as to cool down all the components in the two assemblies.
The cooling system according to claim 1, further comprising

a convection mechanism for cooling down the integrated drivetrain assembly (10) and the integrated power electronics assembly (20) by using an air flow generated by vehicle speed when the vehicle is running, by using a natural air flow when the vehicle is parking, and/or by using an air flow provided by a fan (130) equipped with a condenser (120) .
The cooling system according to claim 1, further comprising

a plurality of first cooling fins (140) arranged onto an outer surface of a housing (14) , containing the electric motor (12) and the reducer (13) , for the heat dissipation towards the outside of the integrated drivetrain assembly (10) .
The cooling system according to any one of claims 1 to 3, wherein

the cooling circuit (110, 110’) comprises a fluid turbulent passage (115) , formed by a plurality of cooling spikes (116) , arranged onto an inner surface (151) of a heatsink cover (15) configured for cooling at least one power switching device provided with the power inverter (11) by contacting with the coolant.
The cooling system according to claim 4, wherein

a plurality of second cooling fins (117) arranged onto an outer surface (152) of the heatsink cover (15) for heat dissipation by convection.
The cooling system according to any one of claims 1 to 3, wherein

the cooling circuit (110, 110’) comprises a reservoir (113) provided within the reducer (13) configured for retaining the coolant to provide a plurality of rotating devices of the electric motor (12) and the reducer (13) , and a housing (14) containing the electric motor (12) and the reducer (13) , with liquid coolant for heat dissipation by contacting with the coolant.
The cooling system according to any one of claims 1 to 3, wherein

the cooling circuit (110, 110’) comprises:

a plurality of nozzles (51) within the integrated drivetrain assembly (10) for spraying the coolant towards the reducer (13) , the electric motor (12) and an inner wall of a housing (14) containing the electric motor (12) and the reducer (13) for heat dissipation, and

a plurality of cooling channels (52) configured for having the coolant flow through at least one of the following elements: the electric motor (12) , the power inverter (11) and the component included in the integrated power electronics assembly (20) for heat dissipation.
The cooling system according to claim 1, wherein

the integrated power electronics assembly (20) comprising an On-board Charger connected to an external power supply, and/or a DC/DC converter and/or a power distribution unit.
The cooling system according to claim 1, further comprising

a pumping device (30) is configured for circulating the coolant through the cooling circuit (110) , the pumping device is a mechanical pump integrated with the integrated drivetrain assembly (10) , or the pumping device is an electrical pump integrated with the integrated drivetrain assembly (10) .
The cooling system according to claim 1, wherein

the integrated power electronics assembly (20) is separated from the integrated drivetrain assembly (10) , the cooling circuit (110’) is fluidly in communication with the integrated power electronics assembly (20) via at least tubes (40) outside of the integrated drivetrain assembly (10) .
The cooling system according to claim 1, wherein

the coolant is ultra-low viscosity oil.
An electrified vehicle, comprising the cooling system according to any one of claims 1 to 11.