CN114583884A

CN114583884A - Power assembly system for electric vehicle and electric vehicle

Info

Publication number: CN114583884A
Application number: CN202011399417.1A
Authority: CN
Inventors: 陈睿进; 陈凯; 孙国强
Original assignee: Valeo Powertrain Nanjing Co Ltd
Current assignee: Valeo Powertrain Nanjing Co Ltd
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2022-06-03
Also published as: KR20230112690A; EP4256680A1; WO2022116940A1; JP2023551936A

Abstract

The present application relates to a powertrain system for an electric vehicle. The powertrain system includes an electric motor, an inverter, a retarder, and a cooling circuit including a single inlet and a single outlet. The cooling circuit is configured such that the oil cooling medium flowing therethrough is distributed throughout the powertrain system to lubricate and cool all components therein. The cooling circuit further comprises a distribution channel for the oil cooling medium in a cooling plate for cooling at least one power switching device in the inverter, wherein at least one flow guide plate is arranged in the distribution channel for the oil cooling medium for guiding the oil flow medium through the distribution channel. The system further comprises a cover corresponding to the cooling plate to close the distribution channel of the oil cooling medium and the cover is in sealing engagement with the at least one baffle. The application also relates to an electric vehicle comprising the power assembly system.

Description

Power assembly system for electric vehicle and electric vehicle

Technical Field

Embodiments of the present application relate generally to a powertrain system for an electric vehicle and a corresponding electric vehicle.

Background

The trend of designing and manufacturing fuel-efficient, low-emission vehicles has been greatly increased, which is inevitable due to environmental concerns and increased fuel costs. The forefront of this trend is the development of Electric vehicles, such as pure Electric vehicles (BEV), Hybrid Electric Vehicles (HEV), Plug-in Hybrid Electric vehicles (PHEV), Range extended Electric Vehicles (EV), Fuel Cell Electric Vehicles (FCEV), and the like, which combine a relatively efficient internal combustion engine and an Electric motor. Electric vehicles may include components, particularly drive trains, that generate heat, and excessive heat build-up may result in reduced performance or component damage. In particular, for high-power electric vehicles, for example BEVs with a power greater than 200kW, the cooling solution involves at least two cooling circuits in the transmission system, such as at least one oil cooling circuit for the electric motor or the retarder and at least one water cooling circuit for the inverter, whereby at least two hydraulic circuits equipped with at least two hydraulic pumps are required in the transmission system, which makes the system design complicated and costly. However, the use of oil cooling for the motor and the speed reducer ensures better cooling performance and cooling efficiency.

For lower power motors, below 100kW, there can be significant benefits by reducing the motor size, while the use of both oil and water cooling throughout the system can be costly. Therefore, a solution that can use only oil for cooling the whole system would become very attractive if the inverter could also be cooled efficiently for oil.

Thus, difficulties in existing inverter cooling designs are overcome, and it is highly desirable to provide improvements in oil cooling designs for powertrain systems of electric vehicles, at least with high efficiency, low cost, and simple structure.

Disclosure of Invention

Aspects and advantages of the present application will be set forth in part in the description which follows, or may be obvious from the description, or may be learned by practice of the application.

In one exemplary aspect, a powertrain system for an electric vehicle is provided. The powertrain system includes an electric motor including a rotor and a stator; an inverter electrically connected to the motor and providing electrical energy to the stator; a reducer connected to the motor and receiving torque of the rotor; and a cooling circuit including a single inlet and a single outlet, the cooling circuit being configured such that an oil cooling medium flowing therethrough is distributed throughout the powertrain system to lubricate and cool all components therein. The cooling circuit further comprises a distribution channel for the oil cooling medium in a cooling plate for cooling at least one power switching device in the inverter, wherein at least one flow guide plate is arranged in the distribution channel for the oil cooling medium for guiding the oil flow medium through the distribution channel. The system further comprises a cover corresponding to the cooling plate to close the distribution channel of the oil cooling medium and the cover is in sealing engagement with the at least one baffle.

In some embodiments, a sealing material is disposed between an inner surface of the cover and an end of each of the at least one baffle.

In some embodiments, the sealing material is disposed on an inner surface of the lid.

In some embodiments, a plurality of radiator fins are provided in the distribution passage of the oil cooling medium, and the radiator fins are arranged in a high density in all the distribution passages of the oil cooling medium.

In some embodiments, the heat fins are located on the cooling plate and cover.

In some embodiments, the at least one power switching device is arranged between two of the cooling plates so that it can be cooled on both sides of the power switching device.

In some embodiments, the oil cooling medium is an ultra-low viscosity oil.

In some embodiments, further comprising an oil pump configured to communicate with an inlet of the cooling circuit to control a flow rate of an oil cooling medium flowing through the cooling circuit,

in some embodiments, the oil pump is located on the electric vehicle side, and the oil pump is connected to the inlet of the cooling circuit when the powertrain system is installed in the electric vehicle, or the oil pump is integrated on the powertrain system.

In some embodiments, the oil pump is a positive displacement pump.

In some embodiments, the drive train further comprises an oil pump, a radiator configured to be connected between an outlet of the cooling circuit and the oil pump to cool the oil cooling medium exhausted by the powertrain system and to convey the cooled oil cooling medium back into the powertrain system.

In some embodiments, the heat sink is integrated on the powertrain system or on the electric vehicle side.

In another exemplary aspect, an electric vehicle is provided, which includes the aforementioned powertrain system.

These and other features, aspects, and advantages of the present application will become better understood with reference to the following description. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

Drawings

A full and enabling disclosure of the present application, 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 illustration of a powertrain system for an electric vehicle according to an exemplary embodiment of the present application.

Fig. 2 is a schematic diagram of a cooling plate and a distribution channel of an oil cooling medium located in the cooling plate according to an exemplary embodiment of the present application.

FIG. 3 is a schematic diagram of a preferred embodiment of a cooling plate and cover mated therewith, according to an exemplary embodiment of the present application.

Fig. 4A is a schematic diagram of a preferred implementation of a cooling plate and power switching device according to an exemplary embodiment of the present application.

Fig. 4B is a schematic diagram of another preferred implementation of a cold plate and power switching device according to an exemplary embodiment of the present application.

Detailed Description

Reference now will be made in detail to embodiments of the application, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the application, not limitation of the application. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the scope or spirit of the application. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present application cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. As used in this specification, the terms "first," "second," and the like may be used interchangeably to distinguish one element from another and are not intended to indicate the position or importance of each element. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Referring now to the drawings, in which like numerals indicate like elements throughout the several views, FIG. 1 illustrates a preferred embodiment of a powertrain system for an electric vehicle. The illustrated powertrain system 1 is generally assembled from an inverter (not shown), a motor 12, and a reducer 13, thereby forming a single component.

The motor 12 may be a synchronous motor or an asynchronous motor. When the motor 12 is a synchronous motor, it may include a wound rotor or a permanent magnet rotor. For nominal supply voltages of 48V to 400V, or for higher powers which may be up to 800V, the peak power provided by the motor may be between 10KW and 80KW, for example of the order of 40 KW. In case the motor is adapted for a high voltage power supply, the nominal power provided by the motor may be 25 KW. In the embodiment shown, the electric motor 12 is a synchronous motor with permanent magnets, which provides peak power between 10KW and 80 KW. The motor 12 may include a stator having three-phase windings, or a combination of two three-phase windings or five-phase windings.

A reducer 13 is associated with the motor 12. The reducer 13 can convert the high speed and low torque of the motor into low speed and high torque. The reducer 13 may comprise two or more reduction gears, one of which is driven by an electric motor, for example, to increase torque by reducing speed. The reducer 13 may also drive a shaft, such as an intermediate shaft, which may be connected to a gear driven by the drive shaft of the motor and another gear having a larger diameter, thereby distributing the reduced driving force to a driven mechanical load (not shown), such as a driven wheel shaft.

In the illustrated embodiment, the motor 12 and the reducer 13 are designed to have a high heat capacity. The inverter may be attached to the motor 12 by wires, and mechanically attached to a wall of the motor 12 or a wall of the reducer 13 or walls of the motor 12 and the reducer 13. The inverter converts direct current ("DC") provided by an electrical energy storage unit (not shown) of electrical energy at nominal voltage to alternating current ("AC") for the electric motor 12. The inverter may include at least one power switching device 17 (shown in fig. 4A and 4B), which may be, for example, a field effect transistor ("FET"), a metal oxide semiconductor field effect transistor ("MOSFET"), or an insulated gate bipolar transistor ("IGBT"). In case of a nominal supply voltage of 48V, the power switching device 17 may be a MOSFET transistor. In case the supply voltage corresponds to a high voltage, the power switching device 17 may be an IGBT.

Referring to fig. 1, the motor 12 is accommodated in a housing (not shown), and the reducer 13 is accommodated in another housing (not shown). The two housings may be integrally formed or assembled from a plurality of housing assemblies, and the two housings may be rigidly secured together, for example by screws, and a sealing wall may be provided between the two housings.

In some embodiments, a heat sink (not shown) may also be provided for dissipating heat towards the outside of the powertrain system 1. The heat sink is carried by the outer surface of the housing. These fins may be formed integrally with the housing. The heat dissipation fins increase the area of the outer surface of the shell, thereby improving the heat dissipation effect of the power assembly system through the shell. The entire outer surface of the housing may be provided with cooling fins. The fins may be arranged in rows and there may be a constant or non-constant spacing between adjacent rows. The rows may or may not have the same orientation. Where appropriate, the same heat sink may extend first to one housing and then to the other housing.

In the embodiment shown, a coolant flow-through cooling circuit 3 is also provided for distributing coolant throughout the powertrain system 1. The coolant flowing in the cooling circuit 3 may be an oil having an ultra-low viscosity. Such ultra low viscosity oils will have a kinematic viscosity value at 40 ℃ of less than 40 and a kinematic viscosity value at 100 ℃ of less than 10. With such ultra-low viscosity oil, all components contained in the powertrain assembly can be lubricated and cooled more efficiently with a lower pressure drop by flowing it through the cooling circuit 3 to the entire powertrain system 1.

The cooling circuit 3 comprises a single inlet 31 and a single outlet 32 provided on the drive train 1. The inlet 31 may be connected to the oil pump 4 to control the flow of the ultra-low viscosity oil through the cooling circuit 3, while the outlet 32 may be connected to a radiator to cool the heated oil discharged from the cooling circuit 3. Meanwhile, the radiator 5 may be connected to the oil pump 4 so as to deliver the cooled oil into the powertrain system 1 through the oil pump 4. In the illustrated embodiment, the oil pump 4 and the radiator 5 are located on the electric vehicle side 2. When the powertrain system 1 is installed in an electric vehicle, the inlet 31 and outlet 32 will be in fluid communication with the oil pump 4 and radiator 5, respectively, through the plurality of hoses 6 in the electric vehicle side 2 so that the ultra-low viscosity oil can automatically flow through the powertrain system 1 to cool and lubricate it during operation.

In some embodiments, the radiator 5 may be integrated with the powertrain system 1 to receive heated oil from the powertrain system 1 and to transfer cooled oil back to the powertrain system.

In some embodiments, the oil pump 4 may be an electric pump or a mechanical pump, and the oil pump 4 may also be integrated with the powertrain system 1, in particular mechanically integrated on the speed reducer 13. The oil pump may be a positive displacement pump to provide the required flow rate of fluid, particularly an accelerated flow rate. In some embodiments, a positive displacement pump instead of a centrifugal pump may apply a higher oil pressure for cooling to increase the ability to dissipate heat from the switchgear absorbed by the radiator.

In some embodiments, the cooling circuit 3 may include an oil reservoir (not shown) disposed within the retarder 13 for retaining the necessary ultra-low viscosity oil, which may ensure a minimum flow of oil for lubrication and cooling inside the powertrain system 1.

Referring to fig. 4A and 4B, the power switching devices 17, such as IGBTs, may be single-sided cooled by oil distribution channels in the cooling plates 18 of the inverter. The power switching device 17 may also be double-sided cooled by oil flowing through two cooling plates, i.e. the power switching device 17 and the cooling plates form a "sandwich" structure.

In some embodiments, since the thermal conductive paste and the additional aluminum heat sink are removed in directly cooling the power switching device 17, i.e., the IGBT module, the power switching device 17 may be in direct contact with the oil so that the thermal dissipation resistance may be improved. The use of direct contact cooling will increase the costs to a limited extent, but can be compensated for, for example, by using a reduced size oil-cooled motor, which necessitates the use of oil cooling by the inverter.

In some embodiments, the power switching device 17 is controlled for full-wave mode or DVPWM mode starting at a given rotational speed, so that power losses from the IGBTs can be reduced, which will allow the use of oil cooling.

With this configuration, the motor 12 can be cooled by oil, and the efficiency at high torque can be greatly improved. The oil-cooled motor will be 5% more efficient than the water-cooled motor under heating conditions. The current through the IGBT can be significantly reduced, limiting the amount of heat that the heat sink and oil will dissipate.

Referring to fig. 2, an oil distribution passage is disposed inside the inverter. Specifically, the oil distribution passage is located in the cooling plate 18 of the inverter, and is formed along the periphery and the inner surface 181 of the cooling plate 18. As shown in fig. 3, the periphery of the cooling plate 18 includes a groove to provide a sealed connection with the cover 19. An auxiliary heat transfer element may be provided in the oil distribution channel to provide additional heat dissipation. As shown in the embodiment, the auxiliary heat transfer element may be a plurality of metal fins 16 provided by the cooling plate 18, in particular by an inner surface 181 of the cooling plate 18, the fins 16 extending from said inner surface 181 towards a cover 19 (as shown in fig. 3), said cover 19 serving to close the oil distribution channel. The secondary heat transfer element is made of a thermally conductive material, such as aluminum. In some embodiments, the cooling fins 16 may entirely cover the oil distribution channels with high density. High density of fins is an important burden on conventional centrifugal water pump circuits due to higher pressure drop, whereas positive displacement oil pumps are almost insensitive to higher pressure drop. The radiator fins 16 may have a circular and/or square (not shown) cross-section, or other shaped cross-section to suit the improvement of the flow rate of the oil cooling medium fluid F. In the case of oil pump feed, oil flows from one side of the cooling plate 18 to the opposite side, the oil pump providing an accelerated flow to increase the flow rate of the oil coolant fluid F, thereby increasing the amount of heat dissipation.

With continued reference to fig. 2, at least one baffle 15 is provided in the oil distribution channel for guiding the oil cooling medium fluid F to flow through the oil distribution channel. In the embodiment shown, one end of each of the two flow guide plates 15 extends from each of the two opposite edges of the cooling plate 18, so that the oil cooling medium fluid F can flow in an "S" shape in the oil distribution channel. It should be understood that the configuration and pattern of the baffles 15 and fins 16 are described herein by way of example only. In other exemplary embodiments, the baffle 15 may be arranged in other configurations and arrangement directions according to different configurations and patterns of the cooling plate 18, so as to better improve the flow velocity of the oil cooling medium fluid F.

Referring to FIG. 3, an exemplary configuration of the cooling plate 18 and the cover 19 adapted thereto is shown. In the conventional design involving a cover, the cover 19 is a flat plate and the heat sink fins 16 are provided on the cooling plate 18. In the present application relating to covers, both the cover 19 and the cooling plate 18 may be provided with cooling fins 16, the cooling fins provided by the cover 19 extending axially towards the cooling plate 18 and the cooling fins provided by the cooling plate extending axially towards the cover 19, such that the cooling fins from the cooling plate 18 and the cover 19 may be spaced apart from each other, narrowing the flow path gap between the cooling fins 16, which will provide a flow velocity of the fluid around the cooling fins 16, thereby further improving the cooling performance of the cooling plate 18. Even if the original water cooling circuit has a large number of fins, the oil-using double-sided fin structure can achieve a cooling level similar to that of water.

With continued reference to fig. 3, when the cover 19 is mated to the cooling plate 18, the flow-guide plates 15 are sealingly engaged with the cover 19 to close the oil distribution channel, in particular, a sealing material 20 is provided between the inner surface 191 of the cover 19 and the free end 151 of each flow-guide plate 15. The sealing material 20 is also applied in a groove 21 provided by the periphery of the cooling plate 18. By applying the sealing material 20 on the cover 19, we can ensure that the gap between the cover 19 and the cooling plate 18 is zero, thereby avoiding flow velocity losses in the oil distribution channel due to the presence of the gap allowing the oil cooling medium fluid F to flow therethrough. In addition, applying the sealing material to the cover may increase the number of fins on the cooling plate, which is a fundamental factor in efficient heat dissipation, whereas if the sealing material has to be applied directly to the cooling plate, for example in a conventional manner at the periphery of the cooling plate, the recesses at the periphery of the cooling plate will occupy a larger surface portion of the cooling plate, thereby reducing the number of fins.

By the construction as described above, it is achieved that only one fluid circuit is used for cooling and lubrication of the powertrain system. In addition, the thermal resistance under the configuration of the present application is only about 10% higher compared to the high density finning water cooling structure.

This written description uses examples to disclose the application, including the best mode, and also to enable any person skilled in the art to practice the application, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the application is defined by the claims, and may include other embodiments that occur to those skilled in the art. Such other embodiments are intended to be within the scope of the claims if they include 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

1. A powertrain system for an electric vehicle, comprising:

an electric motor including a rotor and a stator;

an inverter electrically connected to the motor and providing the stator with electric power;

a speed reducer connected to the motor and receiving a torque of the rotor; and

a cooling circuit including a single inlet and a single outlet, the cooling circuit being configured such that an oil cooling medium flowing therethrough is distributed throughout the powertrain system to lubricate and cool all components therein, the cooling circuit further including a distribution passage of the oil cooling medium in a cooling plate for cooling at least one power switching device in the inverter, at least one baffle plate provided in the distribution passage of the oil cooling medium for guiding the oil cooling medium to flow through the distribution passage, and a cover corresponding to the cooling plate to close the distribution passage of the oil cooling medium and mate with the at least one baffle plate in a sealing manner.

2. The powertrain system of claim 1, wherein:

a sealing material is disposed between the inner surface of the cover and one end of each of the at least one baffle.

3. The powertrain system of claim 2, wherein:

the sealing material is disposed on an inner surface of the cap.

4. The powertrain system of claim 1, wherein:

a plurality of heat dissipation fins are arranged in the distribution channel of the oil cooling medium, and the heat dissipation fins are arranged in all the distribution channels of the oil cooling medium in a high density.

5. The powertrain system of claim 4, wherein:

the heat dissipating fins are located on the cooling plate and the cover.

6. The powertrain system of claim 1, wherein:

the at least one power switching device is arranged between two of the cooling plates so that it can be cooled on both sides of the power switching device.

7. The powertrain system of claim 1, wherein:

the oil cooling medium is ultra-low viscosity oil.

8. The powertrain system of claim 1, further comprising:

an oil pump configured to communicate with an inlet of the cooling circuit to control a flow rate of an oil cooling medium flowing through the cooling circuit, wherein the oil pump is located on an electric vehicle side, the oil pump is connected to the inlet of the cooling circuit when the powertrain system is installed in the electric vehicle, or the oil pump is integrated on the powertrain system; the oil pump is a positive displacement pump.

9. The powertrain system of claim 8, further comprising:

a radiator configured to be connected between an outlet of the cooling circuit and the oil pump to cool the oil cooling medium discharged by the powertrain system and to convey the cooled oil cooling medium back into the powertrain system.

10. The powertrain system of claim 9, wherein:

the radiator is integrated on the power assembly system or positioned on the side of the electric vehicle.

11. An electric vehicle comprising the powertrain of any of claims 1-10.