Active lubricating and cooling system for electric drive axle

Abstract

The invention relates to the technical field of new energy vehicles, and discloses an active lubricating and cooling system for an electric drive axle, which comprises a heat exchanger arranged outside a transmission left shell, and an oil pump and a lubricating oil pipe arranged in an inner cavity of the transmission left shell; a left shell oil duct is arranged in the transmission left shell; a right shell oil duct is arranged in the transmission right shell; an oil inlet and an oil outlet of the heat exchanger are both communicated with the left shell oil duct; the oil pump is in transmission connection with the hollow rotating shaft; a left shell oil spraying hole is formed in the left shell oil duct; an oil pipe oil spraying hole is formed in the lubricating oil pipe; the head end and the tail end of the lubricating oil pipe are respectively connected with an oil outlet of the left shell oil duct and an oil inlet of the right shell oil duct; a right shell oil spraying hole is formed in the right shell oil duct; the right side of the hollow rotating shaft is connected with the right shell oil spraying hole; and a plurality of shaft oil holes are formed in the hollow rotating shaft. Precise lubrication and efficient cooling can be achieved, the transmission efficiency of the system can be effectively improved, the economical performance of the whole vehicle can be optimized, and the cruising ability of the whole vehicle is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and in particular to an active lubrication and cooling system for an electric drive axle. Background Art

[0002] With the increasing shortage of fossil energy resources and increasingly stringent environmental protection requirements, the world is vigorously promoting the development of new energy technologies, which has led to a gradual increase in the number of new energy vehicles and a wider range of applications for pure electric vehicles. At the same time, people have higher and higher requirements for vehicle performance, including vehicle power performance, driving comfort and economic performance. Among them, economic performance is one of the key indicators of a vehicle, and improving the overall efficiency of the system is an important way to optimize the economic performance of the vehicle. As an important component of new energy vehicles, the transmission efficiency of the transmission directly affects the economic performance of the vehicle. The higher the transmission efficiency of the transmission, the better the power and economy of the vehicle. Therefore, improving the transmission efficiency of the transmission is one of the important means to optimize the economic performance of the vehicle.

[0003] In the transmission process of the transmission, oil stirring loss is one of the important factors affecting the transmission efficiency of the transmission. Oil stirring loss refers to the energy loss caused by friction and stirring of the oil inside the transmission during the transmission process. The amount of oil added directly affects the amount of oil stirring loss. The larger the amount of oil added, the more oil there is inside the transmission, the greater the stirring and friction of the oil, the greater the oil stirring loss, and the lower the transmission efficiency of the transmission, and vice versa. In addition, although the oil stirring loss can be reduced by reducing the amount of oil added, thereby improving the transmission efficiency of the transmission. However, in actual applications, if the amount of oil added is too small, the lubrication effect will deteriorate and the oil temperature will increase, which will have a negative impact on the life of the transmission. This makes it difficult to balance efficiency and life, and it is difficult to achieve stable improvement in overall performance. Summary of the invention

[0004] The present invention aims to provide an active lubrication and cooling system for an electric drive axle, which can achieve precise lubrication and efficient cooling, effectively improve the transmission efficiency of the system, help optimize the economic performance of the whole vehicle, and improve the endurance of the whole vehicle.

[0005] The basic solution provided by the present invention is: an active lubrication and cooling system for an electric drive axle, comprising a heat exchanger arranged outside the left housing of the transmission, an oil pump and a lubricating oil pipe arranged in the inner cavity of the left housing of the transmission;

[0006] A left case oil passage is provided in the left case of the transmission; a right case oil passage is provided in the right case of the transmission; the oil inlet and the oil outlet of the heat exchanger are both connected to the left case oil passage; the oil pump and the heat exchanger are in the same oil circuit, and the oil pump is also transmission-connected to the hollow shaft; a left case oil spray hole is provided on the left case oil passage; a plurality of oil pipe oil spray holes are provided on the lubricating oil pipe; the head end of the lubricating oil pipe is connected to the oil outlet of the left case oil passage; the end of the lubricating oil pipe is connected to the oil inlet of the right case oil passage; a right case oil spray hole is provided on the right case oil passage; the right side of the hollow shaft is connected to the right case oil spray hole; and a plurality of shaft oil holes are provided on the hollow shaft.

[0007] The working principle and advantages of the present invention are:

[0008] When the transmission is running, a certain amount of lubricating oil will be stored in the transmission cavity, so that the hollow shaft is in a continuous operation state, driving the oil pump to rotate and generate suction, and then the lubricating oil enters the oil circuit from the transmission cavity through the left housing oil channel. During the oil circuit circulation process, the lubricating oil first passes through the heat exchanger to achieve rapid heat dissipation and cooling, and then passes through the oil pump cavity and enters the left housing oil channel. Part of the oil is sprayed out through the left housing oil injection hole to lubricate and dissipate heat for the bearings; part of the oil enters the lubricating oil pipe and the right housing oil channel, and through the multiple oil pipe oil injection holes and right housing oil injection holes provided therein, multiple bearings and gear meshing positions are lubricated and dissipated; another part of the oil is sprayed from the right housing oil injection hole into the hollow shaft cavity, and through the shaft oil hole, the needle bearings on the shaft are lubricated and dissipated; the lubricating oil from various places finally flows back to the transmission cavity to continue the above cycle.

[0009] The present invention provides an active lubrication and cooling system for an electric drive axle. By designing an active lubrication system in the transmission and adding a heat exchanger, the lubrication and heat dissipation capabilities of the transmission can be effectively improved, so as to further reduce the amount of refueling, reduce oil churning losses, improve the transmission efficiency of the system, optimize the economic performance of the whole vehicle, and improve the endurance of the whole vehicle. In particular, firstly, in this scheme, oil channels are set in the left and right housings of the transmission, and the lubricating oil pipe and the inner cavity of the transmission form a circulating oil circuit, and oil injection holes are set in multiple points of the circulating oil circuit, which can accurately locate the key component positions and key transmission positions in the transmission, realize active lubrication, and have strong lubrication ability; the oil can be distributed relatively evenly layer by layer, and it is not easy to generate refueling redundancy for key components, and the oil can be circulated, which can reduce the demand for refueling from the root, reduce oil churning losses, and improve transmission efficiency.

[0010] Second, this solution adds a heat exchanger to the system to improve the system's cooling capacity. In the circulating oil circuit, the oil will quickly dissipate heat through the heat exchanger, thereby ensuring that the recycled lubricating oil will not overheat the transmission during the oil circuit circulation process, and has a certain cooling effect, which can further improve the system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic diagram of the system structure of a first embodiment of an active lubrication and cooling system for an electric drive axle according to the present invention;

[0012] Figure 2 It is a simulation schematic diagram of a second embodiment of an active lubrication and cooling system for an electric drive axle according to the present invention. DETAILED DESCRIPTION

[0013] The following is a further detailed description through specific implementation methods:

[0014] The marks in the drawings of the specification include: left housing oil passage 11, heat exchanger 12, gear pump 13, left housing oil spray hole 14, lubricating oil pipe 21, first oil pipe oil spray hole 22, second oil pipe oil spray hole 23, third oil pipe oil spray hole 24, fourth oil pipe oil spray hole 25, right housing oil passage 31, first right housing oil spray hole 32, second right housing oil spray hole 33, third right housing oil spray hole 34, fourth right housing oil spray hole 35, hollow rotating shaft 41, first shaft oil hole 42, second shaft oil hole 43, third shaft oil hole 44.

[0015] Embodiment 1

[0016] The embodiment is basically as shown in the attached Figure 1 As shown: an active lubrication and cooling system for an electric drive axle, comprising a heat exchanger 12 arranged outside the left housing of the transmission, an oil pump and a lubricating oil pipe 21 arranged in the inner cavity of the left housing of the transmission.

[0017] The left housing of the transmission is provided with a left housing oil passage 11; the right housing of the transmission is provided with a right housing oil passage 31. The distance between the bottom surface of the left housing oil passage 11 and the oil pan is less than 28 mm. Lubricating oil is stored in the inner cavity of the transmission, and the liquid level of the lubricating oil is higher than the bottom surface of the left housing oil passage 11. With this structure, the lubricating oil in the inner cavity of the transmission is more convenient to enter the left housing oil passage 11, and then enter the oil circuit circulation.

[0018] The oil inlet and the oil outlet of the heat exchanger 12 are both connected to the left housing oil passage 11. The oil pump and the heat exchanger 12 are in the same oil passage, and the oil pump is also in driving connection with the hollow shaft 41; specifically, the oil pump is a gear pump 13; the gear pump 13 and the hollow shaft 41 maintain the same rotation speed.

[0019] Optionally, an oil inlet pipe may be further provided at the oil inlet of the left housing oil passage 11, and the front end of the oil inlet pipe is connected to an oil suction plate and an oil inlet filter, which can assist in oil suction and filter impurities.

[0020] The left housing oil passage 11 is provided with a left housing oil spray hole 14. The lubricating oil pipe 21 is provided with a plurality of oil pipe oil spray holes; the head end of the lubricating oil pipe 21 is connected to the oil outlet of the left housing oil passage 11; the end of the lubricating oil pipe 21 is connected to the oil inlet of the right housing oil passage 31. The right housing oil passage 31 is provided with a right housing oil spray hole; the right side of the hollow rotating shaft 41 is connected to the right housing oil spray hole; the hollow rotating shaft 41 is provided with a plurality of shaft oil holes.

[0021] Specifically, the oil pipe oil injection holes and the right housing oil injection holes are each provided with 4, including the first oil pipe oil injection hole 22, the second oil pipe oil injection hole 23, the third oil pipe oil injection hole 24, the fourth oil pipe oil injection hole 25, and the first right housing oil injection hole 32, the second right housing oil injection hole 33, the third right housing oil injection hole 34, the fourth right housing oil injection hole 35. The shaft oil holes are provided with 3, including the first shaft oil hole 42, the second shaft oil hole 43, and the third shaft oil hole 44.

[0022] In specific applications, when the transmission is running, there is a certain amount of lubricating oil in the transmission cavity, and the liquid level of the lubricating oil is always higher than the bottom surface of the left housing oil channel 11. The hollow shaft 41 is in a continuous operation state, driving the oil pump to rotate and generate suction, thereby allowing the lubricating oil to enter the oil circuit circulation from the transmission cavity (specifically the oil pan) through the left housing oil channel 11.

[0023] During the oil circulation process, the lubricating oil first passes through the heat exchanger 12 to achieve rapid heat dissipation and cooling, and then passes through the oil pump cavity and enters the left housing oil channel 11. Part of the oil is sprayed out through the left housing oil spray hole 14 to lubricate and dissipate heat to the bearings; part of the oil enters the lubricating oil pipe 21 and the right housing oil channel 31, and through the multiple oil pipe oil spray holes and right housing oil spray holes provided therein, lubricate and dissipate heat to multiple bearings and gear meshing positions; some of the oil is sprayed from the fourth right housing oil spray hole 35 into the inner cavity of the hollow shaft 41, and lubricates and dissipates heat to the needle bearings on the shaft through the shaft oil holes; the lubricating oil from various places finally flows back to the inner cavity of the transmission (specifically the oil pan) to continue the above cycle.

[0024] The active lubrication and cooling system for an electric drive axle provided in this embodiment can achieve precise lubrication and efficient cooling, can effectively improve the transmission efficiency of the system, help optimize the economic performance of the whole vehicle, and improve the endurance of the whole vehicle.

[0025] Embodiment 2

[0026] An active lubrication and cooling system for an electric drive axle, based on the first embodiment, the size and position of the oil passage and oil hole are calculated based on simulation analysis; the oil passage includes a left housing oil passage 11 and a right housing oil passage 31; the oil hole includes a left housing oil injection hole 14, an oil pipe oil injection hole, a right housing oil injection hole and an axle oil hole. The diameter of the oil passage is 8 to 12 mm; the diameter of the oil hole is 2 to 5 mm; the setting positions of the multiple oil pipe oil injection holes are respectively close to the bearing setting position and the gear meshing position in the transmission, and the openings of the holes face the bearing raceway position and the gear meshing position; the setting position of the axle oil hole coincides with the bearing setting position on the hollow shaft.

[0027] The simulation analysis includes heat dissipation demand analysis; the heat dissipation demand analysis includes the following steps:

[0028] Step 1: Build a shaft-gear system simulation model based on the transmission structure and set key parameters for it.

[0029] Specifically, in this embodiment, a shaft gear system simulation model is constructed in existing shaft gear simulation software. The key parameters set include part materials, lubricating oil parameters, operating temperature, etc.

[0030] Step 2, perform finite element meshing on key parts in the transmission structure; based on the finite element meshed key parts and the shaft-gear system simulation model, construct a system assembly simulation model.

[0031] Specifically, in this embodiment, the key parts include a transmission housing, a bearing seat, a special-shaped shaft, etc.

[0032] Step 3: Based on the vehicle operating conditions, the system simulation load spectrum is converted and the system assembly is simulated and calculated.

[0033] Specifically, the vehicle usage condition refers to the usage condition of the vehicle in an actual application scenario. In this embodiment, the usage condition data used is obtained from the national standard working condition related data of heavy trucks.

[0034] Step 4: Adjust the tooth surface micro-modification parameters of the shaft-tooth system simulation model to ensure that the gear meshing state meets the standards.

[0035] Specifically, the gear meshing state meeting the standard means that: the gear load is centered, the contact area of ​​the meshing part is greater than 80%, and the load transition of the contact surface is uniform without abnormal mutations.

[0036] Step 5, simulate the system assembly again, export the simulation results, record the operating efficiency and power loss of key parts, and calculate the lubrication and heat dissipation requirements of each key part (including the lubrication amount and lubricating oil pressure required for each key part).

[0037] The simulation analysis also includes flow distribution calculation; the flow distribution calculation includes the following steps:

[0038] S1, based on the current structure of the active lubrication and cooling system for the electric drive axle, build an active lubrication and cooling system simulation model and set key parameters for it.

[0039] In this step, the active lubrication and cooling system simulation model built is a one-dimensional model, and is built based on the existing one-dimensional simulation software. The key parameters set include oil pump performance, lubricant performance, cooler performance, operating temperature, pipeline material, etc.

[0040] S2, setting the size of each pipeline and each oil hole in the active lubrication and cooling system simulation model based on the preset reference value.

[0041] S3, based on the system simulation load spectrum obtained in step 3, simulate and calculate the active lubrication and cooling system; and obtain the lubrication amount and lubrication oil pressure allocated to each lubrication oil spray point as the first simulation result.

[0042] S4, based on the lubrication and heat dissipation requirements of each key component in step 5, verify whether the first simulation result meets the lubrication and heat dissipation requirements; if so, retain the preset reference value as the size value of each pipeline and each oil hole; if not, modify the preset reference value and perform a new simulation calculation; iteratively optimize until the lubrication and heat dissipation requirements are met, and then take the preset reference value at this time as the size value of each pipeline and each oil hole.

[0043] Among them, when modifying the preset reference value, refer to the following conditions for modification: when the lubrication amount shown in the simulation results is less than the lubrication amount in the lubrication and heat dissipation requirements, and the lubrication oil pressure shown in the simulation results is greater than the lubrication oil pressure in the lubrication and heat dissipation requirements, that is, insufficient lubrication and excessive oil pressure occur, then increase the aperture; otherwise (that is, excessive lubrication and insufficient oil pressure occur), reduce the aperture. In addition, in actual applications, the single adjustment step size in the iteration process is determined according to computer performance and development time requirements.

[0044] S5, based on the dimension values ​​and one-dimensional models of each pipeline and each oil hole finally confirmed in S4, and based on the existing CFD simulation analysis software, build a three-dimensional simulation model for the active lubrication and cooling system, such as Figure 2 As shown (part of the simulated oil channel is shown), and simulation verification is carried out.

[0045] The active lubrication and cooling system for an electric drive axle provided in this embodiment can optimize the specific layout of the system through simulation calculation, so that the system can meet the lubrication and heat dissipation requirements of the electric drive axle without generating performance redundancy, thereby helping to accurately control system costs.

[0046] In particular, compared with the existing practical application solutions, the existing solutions often determine the balance point of the refueling amount through experiments, but the test process of this solution is long, the test cost is high, and it is difficult to get the accurate balance point through experiments. This solution chooses to introduce a simulation calculation method. Through simulation calculation to assist in optimizing the specific layout of the system, the layout can be iterated and optimized quickly, so that the final layout of the system can meet the lubrication and heat dissipation requirements of the electric drive axle while the performance does not produce redundancy, so as to achieve the best transmission efficiency and the service life of the transmission. In addition, the simulation process is properly set up, and the flow distribution target is first determined in combination with various actual working conditions, which can assist in realizing the customized active lubrication and cooling system design; in the flow distribution calculation, the one-dimensional model is flexibly selected for calculation, and the three-dimensional model is used for verification, which can ensure a high solution calculation and iteration efficiency, and maintain the accuracy of the final output structure. The overall solution has high operating efficiency and low operating cost.

[0047] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement the scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. An active lubrication and cooling system for an electric drive axle, characterized in that: It includes a heat exchanger arranged outside the left housing of the transmission, an oil pump and a lubricating oil pipe arranged in the inner cavity of the left housing of the transmission; A left case oil passage is provided in the left case of the transmission; a right case oil passage is provided in the right case of the transmission; the oil inlet and the oil outlet of the heat exchanger are both connected to the left case oil passage; the oil pump and the heat exchanger are in the same oil circuit, and the oil pump is also transmission-connected to the hollow shaft; a left case oil spray hole is provided on the left case oil passage; a plurality of oil pipe oil spray holes are provided on the lubricating oil pipe; the head end of the lubricating oil pipe is connected to the oil outlet of the left case oil passage; the end of the lubricating oil pipe is connected to the oil inlet of the right case oil passage; a right case oil spray hole is provided on the right case oil passage; the right side of the hollow shaft is connected to the right case oil spray hole; and a plurality of shaft oil holes are provided on the hollow shaft.

2. The active lubrication and cooling system for an electric drive axle according to claim 1, characterized in that: The distance between the bottom surface of the left housing oil passage and the oil pan is less than 28 mm.

3. The active lubrication and cooling system for an electric drive axle according to claim 1, characterized in that: The oil pipe oil spray holes and the right housing oil spray holes are each provided with 4, and the shaft oil holes are provided with 3.

4. The active lubrication and cooling system for an electric drive axle according to claim 1, characterized in that: The oil pump is a gear pump; the gear pump and the hollow shaft keep the same rotation speed.

5. The active lubrication and cooling system for an electric drive axle according to claim 2, characterized in that: Lubricating oil is stored in the inner cavity of the transmission, and the liquid level of the lubricating oil is higher than the bottom surface of the left housing oil channel.

6. The active lubrication and cooling system for an electric drive axle according to claim 1, characterized in that: The sizes and positions of the oil passages and oil holes are calculated based on simulation analysis; the oil passages include a left housing oil passage and a right housing oil passage; the oil holes include a left housing oil spray hole, an oil pipe oil spray hole, a right housing oil spray hole and a shaft oil hole; the oil passage has a diameter of 8 to 12 mm; the oil hole has a diameter of 2 to 5 mm; the locations of the multiple oil pipe oil spray holes are respectively close to the bearing location and the gear meshing location in the transmission, and the openings of the holes face the bearing raceway location and the gear meshing location; the location of the shaft oil hole coincides with the bearing location on the hollow shaft.

7. The active lubrication and cooling system for an electric drive axle according to claim 6, characterized in that: The simulation analysis includes heat dissipation demand analysis; the heat dissipation demand analysis includes the following steps: Step 1: Build a shaft-gear system simulation model based on the transmission structure and set key parameters for it; Step 2, perform finite element mesh division on key parts in the transmission structure; construct a system assembly simulation model based on the key parts and shaft-gear system simulation model divided by the finite element mesh; Step 3: Based on the vehicle operating conditions, the system simulation load spectrum is converted and the system assembly is simulated and calculated; Step 4, adjusting the tooth surface micro-modification parameters of the shaft-tooth system simulation model to ensure that the gear meshing state meets the standard; Step 5, simulate the system assembly again, export the simulation results, record the operating efficiency and power loss of key parts, and calculate the lubrication and heat dissipation requirements of each key part.

8. The active lubrication and cooling system for an electric drive axle according to claim 7, characterized in that: The simulation analysis also includes flow distribution calculation; the flow distribution calculation includes the following steps: S1, based on the current structure of the active lubrication and cooling system for the electric drive axle, build an active lubrication and cooling system simulation model and set key parameters for it; S2, setting the size of each pipeline and each oil hole in the active lubrication and cooling system simulation model based on the preset reference value; S3, based on the system simulation load spectrum obtained in step 3, simulate and calculate the active lubrication and cooling system; and obtain the lubrication amount and lubrication oil pressure allocated to each lubrication oil spray point as the first simulation result; S4, based on the lubrication and heat dissipation requirements of each key component in step 5, verify whether the first simulation result meets the lubrication and heat dissipation requirements; if so, retain the preset reference value as the size value of each pipeline and each oil hole; if not, modify the preset reference value and perform a new simulation calculation; iteratively optimize until the lubrication and heat dissipation requirements are met, and then take the preset reference value at this time as the size value of each pipeline and each oil hole.

9. The active lubrication and cooling system for an electric drive axle according to claim 8, characterized in that: The active lubrication and cooling system simulation model built in S1 is a one-dimensional model.

10. The active lubrication and cooling system for an electric drive axle according to claim 9, characterized in that: The flow distribution calculation also includes S5, which builds a three-dimensional simulation model for the active lubrication and cooling system based on the size values ​​of each pipeline and each oil hole and the one-dimensional model finally confirmed in S4, and performs simulation verification.

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