Electric drive system, electric vehicle and preparation method

Abstract

The application discloses an electric driving system, comprising a reducer and a motor, the reducer comprises an input shaft, the motor comprises a motor shaft, one end of the input shaft is provided with a first spline, the other end of the input shaft is provided with a transmission gear, one end of the motor shaft is provided with a second spline, the input shaft and the motor shaft are connected through the first spline and the second spline, the meshing tooth surface of the first spline and / or the meshing tooth surface of the second spline and / or the meshing tooth surface of the transmission gear are provided with an insulation layer for blocking shaft current, and the insulation layer is a manganese phosphating layer. The application also discloses an electric vehicle comprising the electric driving system and a preparation method of the manganese phosphating layer. By using the manganese phosphating layer, the application can block the transmission of shaft current, prevent the formation of electric corrosion lines on the gear tooth surface, ensure the good NVH performance (noise, vibration and acoustic roughness) and reliable bearing capacity of the gear, and ensure the reliability of the insulation layer.

Description

Technical Field

[0001] This invention relates to the field of electric vehicles, and more particularly to an electric drive system, an electric vehicle, and a method for manufacturing them. Background Technology

[0002] An electric drive system is a drive system that uses an electric motor as its power source. It includes a motor controller, a motor, and a reducer. The electric drive system is a crucial component of an electric vehicle, directly affecting the vehicle's lifespan and driver safety. During operation, the motor and motor controller generate current and voltage, which are conducted outwards through the motor shaft. These current and voltage are referred to as shaft current and shaft voltage. The shaft current and shaft voltage are transmitted through the splines of the motor shaft to the splines of the input shaft in the reducer, and then to the gears on the input shaft. The oil film between the tooth surfaces of these gears and the tooth surfaces of the external gears that mesh with them is broken down by the aforementioned shaft current and shaft voltage, resulting in an electrochemical reaction and the formation of electro-corrosion patterns on the tooth surfaces. Once electro-corrosion patterns appear on the gear tooth surfaces, their NVH performance (noise, vibration, and acoustic roughness) and reliability capacity will significantly decrease. To address this problem, related technologies have proposed a solution of setting an insulating layer on the spline surface of the motor shaft. For example, Chinese Patent CN105811644A discloses an insulated transmission shaft connecting a motor and a gearbox. This shaft blocks the transmission of shaft current by setting an insulating layer on the transmission shaft, thereby preventing the formation of the aforementioned electro-corrosion patterns. However, the disclosed solution uses a spraying method to spray a layer of Teflon material onto the motor shaft to form an insulating layer. For example, paragraph

[0031] of the patent specification discloses: Shaft A and shaft B are made of carbon structural steel. Shaft A and shaft B are first machined to the required blank size. After surface treatment such as surface passivation, the mating stop of shaft A and shaft B is coated with an insulating layer of Teflon material using an electrostatic spraying process. After the coating is completed, the insulating layer is completely dry before precision machining. Shaft A and shaft B are heat-fitted, and then the outer surface of the integral shaft A and shaft B is precision machined to form splines and teeth to meet the design requirements. Using the insulation layer described above presents the following problems: Since the insulation layer is a Teflon insulation layer formed by a spray coating process, it requires finishing after spraying. Understandably, this finishing process can easily cause localized damage to the insulation layer, leading to inconsistent thickness in different areas. This can result in the insulation performance failing to meet design requirements. In severe cases, it may even completely destroy parts of the insulation layer, causing insulation failure.

[0003] Therefore, there is an urgent need in this field for a new insulating layer structure to solve the problem of electrochemical corrosion, while ensuring that it is not easily damaged and has high reliability. Summary of the Invention

[0004] This invention provides an electric drive system and an electric vehicle, as well as a manufacturing method, to solve the problem of low reliability of the insulation layer used in the prior art to avoid electrochemical corrosion of gear surfaces.

[0005] The present invention adopts the following technical solution: an electric drive system, including a reducer and a motor, wherein the reducer includes an input shaft, the motor includes a motor shaft, one end of the input shaft is provided with a first spline, the other end of the input shaft is provided with a transmission gear, one end of the motor shaft is provided with a second spline, and the input shaft and the motor shaft are splinedly connected by the first spline and the second spline; the meshing tooth surfaces of the first spline and / or the meshing tooth surfaces of the second spline and / or the meshing tooth surfaces of the transmission gear are provided with an insulating layer for blocking shaft current, wherein the insulating layer is a manganese phosphate layer, and the thickness of the manganese phosphate layer is a selected value between 3μm and 8μm.

[0006] The present invention has the following beneficial effects: By setting a manganese-based phosphate layer on the meshing tooth surface of the first spline and / or the meshing tooth surface of the second spline and / or the meshing tooth surface of the transmission gear, the manganese-based phosphate layer blocks the transmission of shaft current, preventing shaft current and shaft voltage from breaking down the oil film between the gear tooth surfaces, thereby preventing the formation of electro-corrosion patterns on the gear tooth surfaces and ensuring that the gear has good NVH performance (noise, vibration, and acoustic roughness) and reliable load-bearing capacity. In addition, the manganese-based phosphate layer is prepared by a phosphate process, which can form a manganese-based phosphate layer (insulating layer) on its meshing tooth surface after the above-mentioned input shaft or motor shaft is manufactured by the phosphate process, without having to form an insulating layer first and then perform finishing as in related technologies. This fundamentally eliminates the possibility of the insulating layer being damaged and ensures the reliability of the insulating layer.

[0007] Preferably, the manganese-based phosphate layer contains manganese, phosphorus and iron, wherein the weight percentage of manganese is between 23% and 24%, the weight percentage of phosphorus is between 18% and 19.5%, and the weight percentage of iron is between 9.5% and 10%.

[0008] Preferably, the surface roughness Ra of the manganese phosphate layer is between 0.4 μm and 1.6 μm.

[0009] Preferably, the withstand voltage range of the manganese phosphate layer is a selected value between 3500V and 5000V, and the breakdown voltage range of the manganese phosphate layer is a selected value between 4100V and 5700V.

[0010] To solve the above-mentioned technical problems, the present invention also adopts the following technical solution: an electric vehicle, including an electric drive system as described in any one of the above technical solutions.

[0011] To solve the above-mentioned technical problems, the present invention also adopts the following technical solution: a preparation method for preparing a manganese-based phosphating layer in an electric drive system as described in any of the above technical solutions, comprising the following steps:

[0012] S100: Determine the part to be processed, which includes the meshing tooth surface of the first spline and / or the meshing tooth surface of the second spline and / or the meshing tooth surface of the transmission gear.

[0013] S200: Degreasing treatment is performed on the area to be treated;

[0014] S300: Perform acid washing on the part to be treated;

[0015] S400: Perform surface adjustment treatment on the part to be processed;

[0016] S500: The part to be treated is subjected to manganese phosphating treatment to form a manganese phosphating layer on the surface of the part to be treated, wherein the thickness of the manganese phosphating layer is a selected value between 3 μm and 8 μm.

[0017] Preferably, the degreasing treatment time in step S200 is 5 min to 10 min, the degreasing treatment temperature is 60°C to 90°C, and the free alkali concentration of the degreasing agent used in the degreasing treatment is 15 pt to 18 pt.

[0018] Preferably, the pickling time in step S300 is 2 to 10 minutes, and the pH value of the hydrochloric acid used in the pickling process is 1 to 2.

[0019] Preferably, the surface conditioning treatment in step S400 takes 0.5 min to 1 min, the temperature is 50°C to 65°C, and the pH value of the surface conditioning agent used in the surface conditioning treatment is 6 to 7.

[0020] Preferably, the time for manganese phosphating in step S500 is 10 min to 20 min, the temperature for manganese phosphating is 94°C to 110°C, and the manganese phosphating solution used for manganese phosphating is a mixed solution containing manganese, iron, phosphorus and oxygen. The total acidity of the manganese phosphating solution is 50 mg / g to 65 mg / g, and the free acid concentration is 5 mg / g to 9 mg / g.

[0021] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of an electric drive system provided in an embodiment of the present invention;

[0023] Figure 2This is a cross-sectional view of the input shaft and the motor shaft in the embodiment.

[0024] Among them, 1. reducer, 10. input shaft, 100. first spline, 101. transmission gear, 2. motor, 20. motor shaft, 200. second spline. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] Embodiments of the present invention will now be described with reference to the accompanying drawings.

[0027] Example: This example provides an electric drive system applied in an electric vehicle. For example... Figure 1 and Figure 2 As shown, the electric drive system includes a reducer 1 and a motor 2. The reducer 1 includes an input shaft 10, and the motor 2 includes a motor shaft 20. One end of the input shaft 10 is provided with a first spline 100, and the other end of the input shaft 10 is provided with a transmission gear 101. One end of the motor shaft 20 is provided with a second spline 200. The input shaft 10 and the motor shaft 20 are splined together by the first spline 100 and the second spline 200. Correspondingly, the reducer 1 and the motor 2 are driven by the splined connection between the input shaft 10 and the motor 2. When the electric drive system is working, both the motor 2 and the motor controller inside generate current and voltage. This current and voltage are transmitted outward through the motor shaft 20 of the motor 2. When transmitted to the transmission gear 101, they break through the oil film on the surface of the transmission gear 101, causing an electrochemical reaction and forming electro-corrosion patterns on the surface of the transmission gear 101. In this embodiment, an insulating layer for blocking shaft current is provided on the meshing tooth surfaces of the first spline 100, the second spline 200, and the transmission gear 101. The insulating layer is a manganese phosphate layer. It is understood that in other embodiments, a manganese phosphate layer can also be provided on any one or two of the meshing tooth surfaces of the first spline 100, the second spline 200, and the transmission gear 101, which can also achieve the effect of blocking shaft current.

[0028] In this embodiment, a manganese-based phosphate layer is provided on the meshing tooth surfaces of the first spline 100, the second spline 200, and the transmission gear 101. This manganese-based phosphate layer blocks the transmission of shaft current, preventing shaft current and voltage from breaking down the oil film between the gear teeth. This prevents the formation of electro-corrosion patterns on the gear teeth, ensuring good NVH performance (noise, vibration, and acoustic roughness) and reliable load-bearing capacity. Furthermore, the manganese-based phosphate layer is prepared through a phosphate process, allowing it to be formed on the meshing tooth surfaces after the input shaft or motor shaft has been manufactured. This eliminates the need for pre-forming the insulation layer and then performing finishing, as is done in related technologies. This fundamentally eliminates the possibility of insulation layer damage, ensuring the reliability of the insulation layer.

[0029] In this embodiment, the thickness of the manganese phosphate layer is 6 μm. It is understood that in other embodiments, the thickness of the manganese phosphate layer can be selected to be between 3 μm and 8 μm, depending on actual needs (e.g., the magnitude of shaft current and shaft voltage). Correspondingly, different thicknesses of the manganese phosphate layer result in different piezoelectric withstand voltage test results. The motor shaft and input shaft are assembled together to form a transmission mechanism. The piezoelectric withstand voltage test results of the transmission mechanism with the aforementioned manganese phosphate layer formed using different test voltages are shown in the table below:

[0030]

[0031] Based on the experimental data in the table above, it can be understood that as the thickness of the manganese phosphate layer increases, its withstand voltage and breakdown voltage also gradually increase. The withstand voltage range of the manganese phosphate layer is a selected value between 3500V and 5000V, and the breakdown voltage range is a selected value between 4100V and 5700V.

[0032] It should also be noted that existing technologies also employ manganese-based phosphating processes to treat gear surfaces and form manganese-based phosphating layers. However, the manganese-based phosphating layers formed by this method are used to enhance the wear resistance of gear surfaces. The principle behind this is that the manganese-based phosphating layers formed by this method have a porous structure, which increases the amount of lubricating oil on the gear surface, thereby improving wear resistance. Unlike the porous manganese-based phosphating layers in the aforementioned methods, the manganese-based phosphating layer produced in this embodiment has a uniform and fine surface without a porous structure. Testing revealed that the surface roughness Ra of the manganese-based phosphating layer in this embodiment is between 0.4 μm and 1.6 μm.

[0033] The transmission mechanism with a manganese phosphate layer provided in this embodiment is manufactured through the following steps:

[0034] S100: Determine the area to be processed; specifically, the area to be processed is the meshing tooth surface of the first spline 100, the meshing tooth surface of the second spline 200, and the meshing tooth surface of the transmission gear 101. It is understood that in other embodiments, one or two of the meshing tooth surfaces of the first spline 100, the second spline 200, and the transmission gear 101 may be selected as the area to be processed.

[0035] S200: Degreasing treatment of the area to be treated; the above-mentioned degreasing treatment refers to cleaning the grease stains on the area to be treated with a degreasing agent. Specifically, it involves saponifying, wetting, dispersing, and emulsifying the grease, thereby causing the grease to detach from the area to be treated and become a soluble substance, making it easy to wash away. Degreasing treatment ensures the cleanliness of the area to be treated and prevents grease stains from hindering the formation of the manganese phosphating layer during the manganese phosphating treatment stage. The degreasing treatment time in this step is 5 to 10 minutes, the degreasing temperature is 60°C to 90°C, and the free alkali concentration of the degreasing agent used in the degreasing treatment is 15 to 18 pt.

[0036] S300: Perform pickling treatment on the area to be treated; the pickling treatment mentioned above refers to removing rust and other impurities from the surface of the area to be treated using an acidic solution. Specifically, in this embodiment, the acidic solution used is hydrochloric acid with a pH value of 1 to 2, and the pickling treatment time in this step is 2 to 10 minutes.

[0037] S400: Surface conditioning treatment of the area to be treated; the aforementioned pickling process may cause unevenness or roughness on the surface of the area to be treated. The surface conditioning treatment involves using a surface conditioner to correct these unevennesses and roughness, while simultaneously removing oil and debris. This surface conditioning treatment also allows for the formation of a very fine crystalline layer on the surface of the area to be treated, accelerating the formation of the manganese phosphating layer during subsequent treatment. The surface conditioner used in this step has a pH of 6 to 7, the treatment time is 0.5 to 1 minute, and the temperature is 50°C to 65°C.

[0038] S500: The area to be treated is subjected to manganese phosphating treatment to form a manganese phosphating layer on its surface. The manganese phosphating treatment involves immersing the area in a manganese phosphating solution, which is a mixed solution containing manganese, iron, phosphorus, and oxygen. The treatment time is 10 to 20 minutes, the temperature is 94°C to 110°C, and the total acidity of the manganese phosphating solution used is 50 mg / g to 65 mg / g, with a free acid concentration of 5 mg / g to 9 mg / g.

[0039] It is understandable that a water rinsing step can be added between steps S200 and S300, and between steps S300 and S400, to further ensure the cleanliness of the part to be treated.

[0040] After the above preparation, a manganese phosphate layer is formed on the meshing tooth surfaces of the first spline 100, the second spline 200, and the transmission gear 101. This manganese phosphate layer contains manganese, phosphorus, iron, and other elements (nickel and oxygen, etc.). The weight percentage of manganese is 23.47%, phosphorus is 18.9%, and iron is 9.76%. It can be understood that adjusting the parameters in the process can change the weight percentage of each element in the final manganese phosphate layer. The weight percentage of manganese is approximately between 23% and 24%, the weight percentage of phosphorus is approximately between 18% and 19.5%, and the weight percentage of iron is between 9.5% and 10%.

[0041] In this invention, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific implementation.

[0042] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An electric drive system comprising a reducer (1) and a motor (2), the reducer (1) comprising an input shaft (10) and the motor (2) comprising a motor shaft (20), characterized in that, One end of the input shaft (10) is provided with a first spline (100), and the other end of the input shaft (10) is provided with a transmission gear (101). One end of the motor shaft (20) is provided with a second spline (200). The input shaft (10) and the motor shaft (20) are connected by the first spline (100) and the second spline (200). The meshing tooth surfaces of the first spline (100) and / or the meshing tooth surfaces of the second spline (200) and / or the meshing tooth surfaces of the transmission gear (101) are provided with an insulating layer for blocking shaft current. The insulating layer is a manganese phosphate layer prepared by a phosphate process after the motor shaft (20) is manufactured. The thickness of the manganese phosphate layer is a selected value between 5 μm and 7 μm. The manganese phosphate layer contains manganese, phosphorus and iron, wherein the weight percentage of manganese is between 23% and 24%, the weight percentage of phosphorus is between 18% and 19.5%, and the weight percentage of iron is between 9.5% and 10%.

2. The electric drive system as described in claim 1, characterized in that, The surface roughness Ra of the manganese-based phosphate layer is between 0.4 μm and 1.6 μm.

3. The electric drive system as described in claim 1 or 2, characterized in that, The withstand voltage range of the manganese phosphate layer is a selected value between 3500V and 5000V, and the breakdown voltage range of the manganese phosphate layer is a selected value between 4100V and 5700V.

4. An electric vehicle, characterized in that, Includes the electric drive system as described in any one of claims 1 to 3.

5. A preparation method for preparing a manganese-based phosphating layer in an electric drive system as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S100: Determine the part to be processed, which includes the meshing tooth surface of the first spline and / or the meshing tooth surface of the second spline and / or the meshing tooth surface of the transmission gear. S200: Degreasing treatment is performed on the area to be treated; S300: Perform acid washing on the part to be treated; S400: Perform surface adjustment treatment on the part to be processed; S500: The part to be treated is subjected to manganese phosphating treatment to form a manganese phosphating layer on the surface of the part to be treated, wherein the thickness of the manganese phosphating layer is a selected value between 3 μm and 8 μm.

6. The preparation method according to claim 5, characterized in that, In step S200, the degreasing treatment time is 5 to 10 minutes, the degreasing treatment temperature is 60°C to 90°C, and the free alkali concentration of the degreasing agent used in the degreasing treatment is 15 to 18 pt.

7. The preparation method according to claim 5, characterized in that, The pickling time in step S300 is 2 to 10 minutes, and the pH value of the hydrochloric acid used in the pickling process is 1 to 2.

8. The preparation method according to claim 5, characterized in that, In step S400, the surface conditioning treatment takes 0.5 min to 1 min, the temperature is 50°C to 65°C, and the pH value of the surface conditioning agent used in the surface conditioning treatment is 6 to 7.

9. The preparation method according to claim 5, characterized in that, In step S500, the manganese phosphating treatment time is 10 min to 20 min, the manganese phosphating treatment temperature is 94℃ to 110℃, and the manganese phosphating solution used in the manganese phosphating treatment is a mixed solution containing manganese, iron, phosphorus and oxygen elements. The total acidity of the manganese phosphating solution is 50 mg / g to 65 mg / g, and the free acid concentration is 5 mg / g to 9 mg / g.

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