Lubricating system of new energy automobile power assembly

Abstract

The invention provides a lubricating system (LS) of a new energy automobile power assembly. Lubricating oil stored in an assembly shell (100) provides circulating oil lubrication for a mechanical part of the power assembly. The mechanical part comprises but is not limited to a motor bearing, a speed reducer and / or a differential mechanism, and the lubricating system (LS) comprises a lubricating loop (200) for providing circulating oil lubrication for the mechanical part and a cooling loop (300) for cooling lubricating oil in the assembly shell (100). The lubrication system (LS) further comprises a cleaning circuit (400) for keeping the lubricating oil not below a certain cleanliness level, the cleaning circuit (400) being started to work only when the oil temperature of the lubricating oil is above a set threshold value. The arrangement of the cleaning loop can reduce the abrasion of friction pairs such as bearings and gears, reduce the failure rate of a power assembly, improve the running reliability of the whole vehicle, prolong the service life of the whole vehicle, and really realize the technical concept that the service life of lubricating oil is the same as that of the vehicle.

Description

Technical Field

[0001] The present invention relates to a lubrication system for a powertrain of a new energy vehicle. Background Art

[0002] New energy vehicles, including hybrid electric vehicles, fuel cell vehicles, and battery electric vehicles, have a powertrain (hereinafter referred to as "powertrain") that includes an electric motor, a reducer, and a differential. For the mechanical parts therein, especially various friction pairs such as bearings and gears, oil bath lubrication and splash lubrication are usually adopted. Here, the so-called "splash lubrication" refers to an automatic lubrication method in which a rotating component (for example, a gear) partially immersed in lubricating oil splashes the lubricating oil onto itself and / or other components (for example, bearings) by rotation. Taking the motor bearing as an example, when the speed of the motor changes, the speed of the gear as a rotating component also changes accordingly, resulting in the lubricating oil sometimes splashing onto the bearing and sometimes not splashing onto the bearing. Intermittent lubrication with too long intervals is likely to cause oil starvation wear of the bearing, leading to premature failure of the bearing.

[0003] To improve the reliability of lubrication, the existing solution is to provide forced circulation oil lubrication for the mechanical parts (especially bearings) to ensure that the bearings can still work properly when the splash lubrication effect is poor. In such a lubrication circuit, the filtration pore size of the filter is generally selected to be above 100 microns to ensure that even viscous lubricating oil can pass through the filter under low-temperature conditions. However, such a large-pore filter is only used to prevent large-particle contaminants from damaging the pump pressure device (oil pump and oil pump drive motor), and cannot meet the high cleanliness requirements of the mechanical parts for the lubricating oil. Taking the elastohydrodynamic lubrication film as an example, sometimes its thickness is even less than 0.1 micron. Such a thin oil film simply cannot enclose pollution particles with a size above 100 microns, and is extremely likely to cause abrasive wear on the surface of the friction pair.

[0004] However, the lubricating oil has a high viscosity and large filtration resistance at low temperatures, which is likely to cause damage to the oil pump drive motor. This has become a technical bottleneck for cleaning the lubricating oil of the powertrain. Coupled with the limitations of space, cost, and energy consumption, the problem of cleaning the lubricating oil of the powertrain has not been effectively solved. The above factors have long hindered people from proposing further lubrication improvement measures for the powertrain.

[0005] There is a need for a lubrication system that can continuously maintain the lubricating oil of the powertrain at a high cleanliness level. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a lubrication system for a new energy vehicle powertrain, which provides circulating oil lubrication for the mechanical parts of the powertrain with the lubricating oil stored in the powertrain housing. The mechanical parts include but are not limited to motor bearings, a speed reducer, and / or a differential. The lubrication system includes a lubrication circuit for providing circulating oil lubrication for the mechanical parts and a cooling circuit for cooling and dissipating heat from the lubricating oil in the powertrain housing. In addition, the lubrication system further includes a cleaning circuit for maintaining the lubricating oil at no less than a certain cleanliness level, and the cleaning circuit is only activated when the oil temperature of the lubricating oil is higher than a set threshold.

[0007] The lubrication system additionally provides a cleaning circuit outside the traditional lubrication circuit, and the cleaning circuit is only activated when the temperature is higher than a set threshold. The cleaning circuit that is activated only when the oil temperature is high eliminates the long-standing technical prejudice that the lubricating oil of the powertrain cannot be filtered with high precision due to the aforementioned various limitations. In fact, after the viscosity of the lubricating oil decreases due to temperature rise, it becomes realistically possible to perform fine filtration on the lubricating oil. In addition, contrary to intuition, the additional presence of the cleaning circuit does not occupy too much space, and due to limited energy consumption, a single precision filtration can ensure that the lubricating oil remains at a high cleanliness level for a relatively long time. Therefore, the setting of the cleaning circuit can reduce the wear of friction pairs such as bearings and gears, reduce the failure rate of the powertrain, improve the reliability and service life of the vehicle operation, and truly realize the technical concept of the lubricating oil having the same service life as the vehicle.

[0008] The following will describe in detail various embodiments of the present invention and the beneficial technical effects with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Showing a top view of the powertrain and a circuit distribution diagram of its lubrication system; and

[0010] Figure 2 Showing a side view of the powertrain and a circuit distribution diagram of its lubrication system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] Figure 1 and 2Show the external structure of the powertrain and the circuit distribution diagram of the lubrication system arranged around the powertrain from the top view and side view respectively. For the sake of simplicity, the powertrain 100 is only drawn as the shape of its housing (hereinafter referred to as the "assembly housing", also marked with the number "100") in the figure, and the power motor 101, reducer 102, differential 103 and the output half shafts 104 of the differential contained therein are marked at their corresponding positions in the housing. The lubrication system LS uses the assembly housing 100 as an oil sump to provide circulating oil lubrication for the mechanical parts of the assembly. Among them, the mechanical parts include but are not limited to bearings, gears and any other type of friction pair. In addition, the assembly housing 100 is in air communication and pressure balance with the outside through a breather valve 600, and the breather valve 600 has the functions of preventing water intrusion and oil splashing.

[0012] Taking bearing lubrication as an example, the lubrication system LS includes a circulating oil lubrication circuit (hereinafter referred to as the "lubrication circuit") 200 that provides forced lubrication for the bearings, forming a backup protection scheme with the splash lubrication described above. The lubrication circuit 200 includes a pipeline 201, a large-aperture filter 202, an oil pump 203, an oil pump drive motor 204 and a pressure transmitter 205. Through the operation of the motor 204 and the oil pump 203, the lubricating oil in the assembly housing 100 is circulated and transported to the components to be lubricated in the mechanical parts, that is, bearings, gears and / or other friction pairs. Taking the motor bearing as an example, the lubrication circuit 200 can lubricate more than two bearings through the pipeline 201 in a parallel or series manner (not shown).

[0013] The lubrication circuit 200 is also provided with a pressure transmitter 205 downstream of the oil pump 203 for monitoring the oil outlet pressure of the pipeline 201. If the pressure is too high, it means that the downstream section of the pipeline 201 is blocked; if the pressure is zero, it means that the oil pump 203 and / or the motor 204 fails. The pressure transmitter 205 can be connected to the vehicle control unit (VCU) or other control systems (not shown) for monitoring the working state of the lubrication circuit 200.

[0014] In the lubrication circuit 200, the filter 202 is still the large-aperture filter described above, and the lubricating oil can pass through it under both high-temperature and low-temperature conditions, which can prevent large-particle contaminants from damaging the oil pump 203. As a preferred implementation, part or all of the pipeline 201 can be integrated on the outer wall of the assembly housing 100, allowing the filter 202 to be externally connected to the pipeline 201, so as to facilitate regular replacement.

[0015] In addition to the lubrication circuit 200, the lubrication system LS also provides a circulating oil cooling circuit (hereinafter referred to as "cooling circuit") 300. The cooling circuit 300 includes a pipeline 301, an oil pump 302, an oil pump drive motor 303, a pressure transmitter 304, and a cooling unit CU. Among them, the cooling unit CU further includes a fan 305, a fan drive motor 306, and a heat exchanger 307. The oil pump motor 303 and the fan motor 306 are both arranged to be able to accept the control of the temperature transmitter 500 and are used to start running when the oil temperature is relatively high (for example, exceeding 40 °C). In order to obtain the best cooling effect, the oil pump motor 303 and the fan motor 306 can be arranged to work simultaneously when the oil temperature reaches a specific threshold.

[0016] Similar to the lubrication circuit 200, the pressure transmitter 304 in the cooling circuit 300 is also used to monitor whether the pipeline 301 is blocked downstream of the oil pump 302 and whether the oil pump 302 and the motor 303 fail. For the purpose of heat dissipation, it is preferable that part or all of the pipeline 301 of the cooling circuit 300 is integrated on the outer wall of the assembly housing 100. As a preferred embodiment, the cooling unit CU (especially the heat exchanger 307) can be formed as part of the vehicle thermal management system. For example, it heats the lubricating oil under low-temperature conditions and cools the lubricating oil under high-temperature conditions to achieve the best utilization of energy.

[0017] As an important feature of the present invention, the lubrication system LS additionally includes a cleaning circuit 400. The cleaning circuit 400 includes a pipeline 401, an oil pump 402, an oil pump drive motor 403, a pressure transmitter 404, and a filtering unit FU. Among them, the filtering unit FU further includes a precision filter 405, a differential pressure transmitter 406, and a one-way pressure valve 407. In the working state, the lubricating oil is driven by the oil pump 402 and the motor 403 through the pipeline 401 and the filtering unit FU, and finally returns to the assembly housing 100. The cleaning circuit 400 is used to keep the lubricating oil in the assembly housing 100 always at a certain high cleanliness level.

[0018] As the core component of the filtering unit FU, the precision filter 405 preferably has a filtration ratio β3≥100 and / or β 5[C] ≥5000, and more preferably a filtration ratio β3≥200 and / or β 5[C]≥1000. To extend the service life, the fine filter 405 preferably uses high dirt-holding capacity filter elements such as folded and / or depth types. Among them, the folded filter element refers to a filter element that increases the filtration area and improves the filtration efficiency through a folded design, and the depth filter element refers to a filter element in which impurities are intercepted in a filter layer with a certain thickness during filtration. To further improve the filtration accuracy, the fine filter 405 preferably uses a small cellulose packing type filter element. The cellulose packing type filter element has excellent depth filtration ability and can remove any type of contaminants as small as 0.1 micron, including hard and soft particles, bacteria, water (free, bound, and emulsified water), oxides, insoluble varnishes, etc.

[0019] Similar to the lubrication circuit 200 and the cooling circuit 300, the pipeline 401 of the cleaning circuit 400 is also preferably partially or fully integrated on the outer wall of the assembly housing 100, allowing the fine filter 405 to be firmly externally connected to the pipeline 401 in a quick-change manner. The fine filter 405 can be a filter that is easy to replace or can include an easy-to-replace filter element.

[0020] In the filtration unit FU, the differential pressure transmitter 406 is used to detect the differential pressure on both sides of the fine filter 406 and transmit the measurement result to the vehicle control unit VCU or the relevant control system. A too high differential pressure indicates an increase in impurities in the filter element, resulting in blockage, meaning the filter element needs to be replaced. As an additional or alternative option, the replacement of the fine filter 406 or its filter element can also be combined with the vehicle's maintenance plan. For example, it can be replaced regularly or according to the mileage. The function of the one-way pressure valve 407 is to automatically conduct the cleaning circuit 400 when the filter 406 is blocked, so as to protect the oil pump 402 and the oil pump drive motor 403.

[0021] It is necessary to point out that the drive motor 403 of the oil pump 402 must be set to be controlled by the signal of the temperature transmitter 500 and is only allowed to work when the lubricating oil temperature reaches a predetermined threshold (for example, ≥40°C) to avoid an increase in the viscosity of the lubricating oil at low temperatures, and the huge resistance when passing through the fine filter 405 may damage the drive motor 403. If a particle counter (a precise cleanliness monitoring device) is provided in the housing assembly 100, its detection result can be used to control when the cleaning circuit 400 is put into operation. As another option, the working interval of the cleaning circuit 400 can also be set according to experience. The finely filtered lubricating oil will maintain a high cleanliness level for a quite long time, so the cleaning circuit 400 will not be started frequently and will not impose a heavy burden on the energy consumption of new energy vehicles.

[0022] Similar to the lubrication circuit 200, the pipeline 401 of the cleaning circuit 400 can also be partially or fully integrated on the outer wall of the assembly housing 100, allowing the precision filter 405 to be externally connected to the pipeline 401, thus facilitating regular replacement. As a preferred implementation, as Figure 2 shown, the bottom of the assembly housing 100 can be constructed in a funnel shape that gradually narrows from top to bottom, and the inlet of the pipeline 401 of the cleaning circuit 400 is arranged at the lowest point of the funnel. With this design, when the vehicle stays on a horizontal road surface, the pollutant particles in the lubricating oil will gather at the lowest point of the housing 100 under the action of gravity, and are easily filtered out from the lubricating oil first when the cleaning circuit 400 operates, thereby improving the filtering efficiency.

[0023] As a preferred implementation, the cleaning circuit 400 and the cooling circuit 300 can also be integrated into the same circuit. For example, the filtering unit FU can be integrated into the cooling circuit 300, downstream of the oil pump 302 (not shown). This solution is based on the common premise that both the cooling circuit 300 and the cleaning circuit 400 are only allowed to start when the oil temperature is relatively high, achieving unity in the usage level for two circuits with different functions. The cooling and cleaning oil circuit formed in this way only requires a set of oil pump, oil pump drive motor, and pressure transmitter, thus simplifying the composition and reducing the cost.

[0024] The powertrain 100 described above adopts a parallel-axis drive axle structure, that is, the respective axes of the motor 101, the reducer 102, and the differential 103 are parallel to each other. However, those skilled in the art should understand that the lubrication system LS is equally applicable to other types of powertrains with coaxial or vertical-axis drive axle structures.

[0025] The lubrication system of the new energy vehicle powertrain described above is not limited by the specific implementation, and the more general technical solution will be subject to the limitations in the appended claims. Any changes and improvements to the present invention that comply with the limitations in the appended claims fall within the protection scope of the present invention.

Claims

1. A lubrication system (LS) for a powertrain of a new energy vehicle provides circulating oil lubrication for the mechanical parts of the powertrain with the lubricating oil stored in the assembly housing (100). The mechanical parts include, but are not limited to, motor bearings, a speed reducer, and / or a differential. The lubrication system (LS) includes a lubrication circuit (200) for providing circulating oil lubrication for the mechanical parts and a cooling circuit (300) for cooling and dissipating heat from the lubricating oil in the assembly housing (100), and is characterized in that: The lubrication system (LS) further includes a cleaning circuit (400) for maintaining the lubricating oil at no less than a certain cleanliness level, and the cleaning circuit (400) is activated only when the oil temperature of the lubricating oil is higher than a set threshold value.

2. The lubrication system (LS) according to claim 1, characterized in that: The cleaning circuit (400) employs a precision filter (405), and the filtration pore size of the precision filter (405) is much smaller than that of the large-pore filter (202) used in the lubrication circuit (200).

3. The lubrication system (LS) according to claim 2, wherein: The filtration ratio β3 of the precision filter (405) is ≥ 100 and / or β 5[C] ≥ 500.

4. The lubrication system (LS) according to claim 3, characterized in that: The precision filter (405) uses a high dirt-holding capacity filter element of the folded type and / or the depth type.

5. The lubrication system (LS) according to claim 4, characterized in that: The precision filter (405) uses a small cellulose packing type filter element.

6. The lubrication system (LS) according to any one of claims 1 to 5, characterized in that: The precision filter (405) is arranged to be monitored and protected by a differential pressure transmitter (406).

7. The lubrication system (LS) according to any one of claims 1 to 5, characterized in that: The pipeline (401) of the cleaning circuit (400) is partially or entirely integrated on the outer wall of the assembly housing (100), and the precision filter (405) is externally connected to the pipeline (401) in a replaceable manner.

8. The lubrication system (LS) according to any one of claims 1 to 5, characterized in that: The cleaning circuit (400) is arranged to be controlled by an oil cleanliness monitoring device.

9. The lubrication system (LS) according to any one of claims 1 to 5, characterized in that: The cleaning circuit (400) and the cooling circuit (300) are integrated into one body and share a set of lubricating oil pumping devices.

10. The lubrication system (LS) according to any one of claims 1 to 5, characterized in that: The assembly housing (100) is constructed such that its bottom has a funnel shape that gradually narrows from top to bottom, and the inlet of the pipeline (401) of the cleaning circuit (400) is arranged at the lowest point of the funnel.

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