Method for testing compatibility of lubricating oil and motor material

Abstract

The invention discloses a lubricating oil and motor material compatibility test method, which comprises the following steps: adding a proper amount of lubricating oil sample into a sealing tank, putting an oil-cooled motor material to be tested into the sealing tank, and completely immersing the oil-cooled motor material under the liquid level of the lubricating oil; filling oxygen into the sealing tank, and pressurizing the sealing tank to a test state; activating the magnetic stirrer to work, putting the sealed tank into a high-temperature box which is heated to 155 DEG C in advance, heating substances in the tank to 155 + / -2 DEG C for not more than 30 minutes, keeping the temperature constant for 40 hours, taking out the sealed tank, putting the sealed tank into a low-temperature box which is cooled to-45 + / -2 DEG C, cooling the substances in the tank to-45 DEG C for not more than 30 minutes, keeping the temperature constant for 8 hours, forming a cycle, and increasing the cycle times according to requirements; and after the constant temperature is finished, cooling the sealing tank to room temperature, exhausting, opening the sealing cover, and taking out the sample for detection. By simulating the actual working condition, the test is close to reality, and the aging efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of oil-cooled motor heat dissipation technology, and in particular to a method for testing the compatibility of lubricating oil and motor materials. Background Technology

[0002] A high-efficiency heat dissipation system is fundamental to suppressing motor temperature rise, improving motor operational stability, and extending motor lifespan; it is also a crucial guarantee for achieving high power density in motors. Air cooling, evaporative cooling, and liquid cooling systems are three common types of motor heat dissipation systems. Air cooling systems can be further divided into natural air cooling systems and forced air cooling systems, widely used in small-power motors. Evaporative cooling systems utilize the phase change of the cooling medium to absorb heat and achieve motor cooling; they are widely used in the heat dissipation systems of megawatt-level large-capacity generator sets. Liquid cooling systems have extremely high heat dissipation efficiency, up to 50 times that of air cooling, and are suitable for applications requiring high motor heat generation and high heat flux density.

[0003] Liquid cooling systems are generally classified into two categories based on their working medium: water-cooled systems and oil-cooled systems. Compared to water, oil has better insulation properties, a higher dielectric constant, a much higher boiling point than water, and a much lower freezing point. This makes oil less prone to solidification at low temperatures and less prone to boiling at high temperatures, improving the motor system's adaptability to the external environment and preventing corrosion damage such as cavitation and scale buildup. Furthermore, oil cooling systems facilitate the integration of the motor and gearbox, improve bearing lubrication and cooling, and heating the gearbox oil at low ambient temperatures can simultaneously enhance lubrication efficiency.

[0004] Oil cooling can be either direct or indirect. Direct oil cooling involves the oil medium flowing inside the motor and directly exchanging heat with the motor windings, stator, and other heat-generating components. Alternatively, it can circulate within the motor housing, without direct contact between the oil medium and these components. Direct oil cooling, where the oil medium directly contacts the internal heat-generating components, offers extremely high heat dissipation efficiency and is an effective solution for heat dissipation challenges in high-power-density motors. It is particularly suitable for high-power-density motor applications in aerospace, armored vehicles, and other mobile platforms.

[0005] In direct oil-cooled heat dissipation systems, because the oil medium is in direct contact with heat-generating components such as motor windings and stator, the physicochemical compatibility between the motor winding insulation system and the oil medium under long-term high-temperature operating conditions will affect the insulation performance of the motor windings and the characteristics of the oil medium, ultimately impacting the motor's service life. For the oil medium in directly oil-cooled motors, it must satisfy both the lubrication of the transmission system and the cooling of the motor's heat-generating components, while also considering copper wire corrosion and the material compatibility with the winding insulation system, including the insulating impregnation varnish, enameled wire, and insulating skeleton materials.

[0006] Existing patent document CN118584257A discloses a test method for analyzing the physicochemical compatibility of the insulation system of a direct oil-cooled motor winding with the cooling lubricating oil. In the experiment, it simulates the working state of the insulation and heat dissipation system of a direct oil-cooled motor under working conditions. In the analysis process, it not only measures the changes in the physicochemical properties of each component during high-temperature aging, but also tests and analyzes the electrical performance parameters of each component during high-temperature aging.

[0007] Currently, oil-cooled motor technology is widely used in new energy electric vehicles. However, there are no national or industry standards for assessing the compatibility of materials such as copper wires, insulating paper, impregnating resin, sleeves, and binding tape within the motor with lubricating oil. The TCEEIA 415-2023 "Technical Specification for Insulation Structure of Drive Motors for New Energy Vehicles," formulated by the China Electrical Equipment Industry Association, includes a test for the oil resistance of insulation components in directly oil-cooled motors. However, the aging test conditions set in this standard are static and oxygen-deficient environments, which cannot simulate actual working conditions, leading to conclusions that differ significantly from actual test results. Therefore, this study adopted publicly available methods from Chapter 5.3 "Rapid Temperature Change Test" and Chapter 5.4 "Oil Resistance Test of Insulation Components" of TCEEIA 415-2023.

[0008] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0009] The main purpose of this invention is to propose a method for testing the compatibility of lubricating oil and motor materials, which solves the problem of no stirring in the oil resistance test of oil-cooled motor materials in TCEEIA415-2023 "Technical Specification for Insulation Structure of Drive Motor of New Energy Vehicle". This invention adds magnetic stirring and takes into account the sealing effect of the sealed container.

[0010] To address the issue of oxygen deficiency in the sealed container during the oil resistance test of oil-cooled motor materials in TCEEIA 415-2023 "Technical Specification for Insulation Structure of Drive Motors for New Energy Vehicles", this invention introduces oxygen at a certain pressure into the container before the test via an inflation valve on the sealed cover, allowing the material inside the container to age rapidly under oxygen-rich and agitated conditions.

[0011] Therefore, this invention proposes a method for testing the compatibility of lubricating oil and motor materials.

[0012] Preferably, the present invention may also have the following technical features:

[0013] A method for testing the compatibility of lubricating oil with motor materials includes the following steps:

[0014] Add an appropriate amount of lubricating oil sample to the sealed container, place the oil-cooled motor material to be tested into the sealed container, and completely immerse it below the surface of the lubricating oil.

[0015] Fill the sealed container with oxygen and pressurize it to the test state;

[0016] Activate the magnetic stirrer and place the sealed container in a high-temperature chamber preheated to 155±2℃. The time for heating the contents of the container to 155±2℃ should not exceed 30 minutes. After maintaining the temperature for 40 hours, remove the sealed container and transfer it to a low-temperature chamber that has been cooled to -45±2℃. The time for cooling the contents of the container to -45±2℃ should not exceed 30 minutes. Maintain the temperature for 8 hours. This completes one cycle. Increase the number of cycles as needed.

[0017] After the constant temperature period is over, place the sealed container in room temperature to cool to room temperature, vent the air, open the sealed lid, and take out the sample for testing.

[0018] Furthermore, after the lubricating oil is added to the sealed container, the level of the lubricating oil is below 2 / 3 of the height of the sealed container, and at least 1 / 3 of the space in the sealed container is filled with air.

[0019] Furthermore, under test conditions, the internal pressure of the sealed container is increased to above standard atmospheric pressure but less than 830 kPa.

[0020] Furthermore, the sealed container includes a container body, a sealing cap, and a magnetic stirrer. The inner cavity of the container body is provided with a motor material fixing bracket, the top of the container body is equipped with a sealing cap, and the bottom is provided with a magnetic stirrer. The sealing cap is provided with an air supply pipe, and the air supply pipe is provided with an air filling valve.

[0021] Furthermore, a pressure sensor is provided on the upper part of the sealed container.

[0022] Furthermore, during the oxygen filling and air purging process, oxygen is blown into the sealed container to increase the internal air pressure. After filling is completed, the filling valve is switched from the filling state to the venting state to release the gas in the sealed container and depressurize, completing one filling and venting cycle. Then, the filling valve is switched back to the filling state, and the filling and venting operation is repeated until the oxygen completely replaces the air. Finally, the filling valve is switched back to the filling state to pressurize the sealed container to the test state.

[0023] Furthermore, the sealing cover is connected to an air inlet pipe and an exhaust pipe, and the air inlet pipe is equipped with an air inlet switch, while the exhaust pipe is equipped with a one-way valve and an exhaust switch.

[0024] Furthermore, the end of the air inlet pipe is connected to an oxygen cylinder, and oxygen is introduced into the sealed container. As a large amount of oxygen is poured into the sealed container, the air inside the sealed container is discharged from the exhaust pipe, and the oxygen completely replaces the air inside the sealed container.

[0025] Furthermore, the magnetic stirrer operates at a speed of less than 2000 rpm.

[0026] Furthermore, the top of the sealed container is provided with a flange, and an annular groove is opened on the flange to assemble a polytetrafluoroethylene sealing ring. An assembly hole is also provided to connect the sealing cover; the sealing cover is installed on the top of the sealed container by bolts.

[0027] Furthermore, the lubricating oil contains 0-0.5% water.

[0028] The beneficial effects of this invention compared to existing technologies include: when blowing oxygen into the sealed container, the container is continuously circulated through inflation and deflation three times to ensure that the air inside is completely replaced, thus guaranteeing the purity of the oxygen inside the container. By increasing the aging test conditions, a magnetic stirrer is installed at the bottom of the stainless steel sealed container, and oxygen at a certain pressure is blown in. Accelerated aging tests are conducted at high and low temperatures, making this invention closer to actual working conditions and yielding more convincing data. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the sealed container structure of the present invention.

[0030] Figure 2 This is a schematic diagram of yet another embodiment of the sealing cap of the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope or application of the present invention.

[0032] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0033] like Figure 1 The method for testing the compatibility of lubricating oil with motor materials, as shown, includes the following steps:

[0034] Add an appropriate amount of lubricating oil sample to the sealed container, and place the oil-cooled motor material 5 to be tested into the sealed container, ensuring it is completely submerged below the surface of the lubricating oil.

[0035] In the above steps, after the lubricating oil is added to the sealed container, the level of the lubricating oil is below 2 / 3 of the height of the sealed container, so that at least 1 / 3 of the space in the sealed container is filled with air.

[0036] Oxygen is introduced into the sealed container, and the container is pressurized to the test state. Under the test state, the internal pressure of the sealed container is increased to above the standard atmospheric pressure and less than 830 kPa, preferably 500~680 kPa.

[0037] Preferably, the sealed container is a circular container, comprising a container body 1, a sealing cap 2, and a magnetic stirrer 5. A motor material fixing bracket 3 is provided in the center of the inner cavity of the container body 1. The sealing cap 2 is installed on the top of the container body 1, and the magnetic stirrer 5 is provided at the bottom. The magnetic stirrer 5 is used to stir the lubricating oil inside the container body 1. An air supply pipe 6 is provided on the sealing cap 2, and an air filling valve 7 is provided on the air supply pipe 6. To ensure the oxygen purity inside the sealed container, the air in the sealed container needs to be replaced with oxygen, so that the sealed container is filled with lubricating oil and oxygen. Preferably, the magnetic rotor 51 is coated with a polytetrafluoroethylene layer.

[0038] Preferably, a pressure sensor is installed on the upper part of the sealed container to measure the internal pressure of the sealed container, such as on the sealing cover 2. In this way, when filling with oxygen and purging with air, oxygen is blown into the sealed container to increase the internal air pressure. After a certain amount of oxygen is filled, the filling valve 7 switches from the filling state to the venting state to release the gas in the sealed container and depressurize, completing one filling and venting operation. Then, the filling valve 7 is switched back to the filling state, and the filling and venting operation is repeated twice. Finally, the filling valve 7 is switched back to the filling state to pressurize the sealed container to the test state.

[0039] Preferably, when blowing oxygen into the sealed container, the container is continuously purged and degassed three times to ensure that the air inside the container is completely replaced. Each time oxygen is purged, the amount of oxygen to be purged is calculated based on the volume of the sealed container and the amount of lubricating oil, ensuring that the amount of oxygen purged each time is greater than the difference between the volume of the sealed container and the volume of the lubricating oil.

[0040] Another way to vent air is to combine... Figure 2The air supply pipe 6 on the sealing cover 2 includes an inlet pipe 61 and an outlet pipe 62. The inlet pipe is equipped with an inlet switch 63, and the outlet pipe 62 is equipped with a one-way valve 64 and an outlet switch 65. In this way, by connecting the end of the inlet pipe 61 to an oxygen cylinder, oxygen is introduced into the sealed container. As a large amount of oxygen is poured into the sealed container, the air inside the sealed container is discharged through the outlet pipe 62. Simultaneously, the one-way valve 64 prevents air from flowing back into the sealed container, thus completely replacing the air inside the sealed container with oxygen and ensuring the purity of the oxygen inside. Preferably, when installing the motor material holder 8, interference between the motor material holder 8 and the magnetic rotor 51 of the magnetic stirrer 5 is avoided. For example, a boss 13 is provided on the inner wall of the sealed container, and the motor material holder 8 is installed on the boss 13, so that the motor material holder 8 and the magnetic rotor 51 are at a certain distance. The magnetic stirrer 5 is an existing product. A flange is provided on the top of the sealed container, and an annular groove is formed on the flange to assemble a polytetrafluoroethylene (PTFE) sealing ring. An assembly hole is also provided to connect a sealing cap. The sealing cap is bolted to the top of the sealed container.

[0041] Activate the magnetic stirrer 5, place the sealed container in a high-temperature chamber preheated to 155±2℃, and heat the contents to 155±2℃ for no more than 30 minutes. After holding the temperature for 40 hours, remove the sealed container and immediately place it in a low-temperature chamber cooled to -45±2℃. The transition time from the high-temperature chamber to the low-temperature chamber should be less than 30 seconds, and the cooling time to -45±2℃ should be no more than 30 minutes. Hold the temperature for 8 hours. This constitutes one cycle, and the number of cycles can be increased as needed. During the test, the motor material can complete the test in only 2-8 days under oxygen-rich and stirred conditions, achieving aging and improving work efficiency. In contrast, the TCEEIA 415-2023 method is a static test during high and low temperature tests, where the oil is not agitated, resulting in slow oil heating / cooling and a slow aging process, which cannot simulate the motor operation process. Preferably, the lubricating oil contains 0-0.5% water during the test.

[0042] Preferably, the magnetic stirrer 5 operates at a speed of less than 2000 rpm, and more preferably 60-1200 rpm. In this embodiment, by stirring and injecting oxygen at a certain pressure, and conducting an aging test at a certain temperature, the aging efficiency is higher than that of the TCEEIA 415-2023 method.

[0043] The above steps are performed in accordance with Chapter 5.3 "Rapid Temperature Change Test" and Chapter 5.4 "Oil Resistance Test of Insulation Components" of TCEEIA 415-2023 "Technical Specification for Insulation Structure of Drive Motor for New Energy Vehicles".

[0044] After the constant temperature period is over, place the sealed container in room temperature to cool to room temperature, vent the air, open the sealed lid, and take out the sample for testing.

[0045] The above technical solution adds aging test conditions. A magnetic stirrer is installed at the bottom of the stainless steel sealed tank, and oxygen at a certain pressure is blown in. Accelerated aging tests are carried out at high and low temperatures, making the embodiments of the present invention closer to actual working conditions and the data obtained more consistent with reality.

[0046]

[0047] Table 1 compares the kinematic viscosity, total acid value, breakdown voltage, volume resistivity, and volume resistivity of several sample oils at 100℃. Sample 1 is a new oil-cooled motor coolant; Sample 2 is a used oil-cooled motor coolant after 200 hours of reliability bench testing; Sample 3 is a sample tested 8 days after the TCEEIA 415-2023 method test; and Sample 4 is a sample tested 4 days after the method of this invention. As shown in Table 1, in terms of the main aging indicators, breakdown voltage and volume resistivity, the aging effect of Sample 4 (using the method of this invention) is significantly better than that of Sample 3 (using the TCEEIA 415-2023 method).

[0048]

[0049] Table 2 shows examples of aging times. Depending on the number of cycles, the aging time of the present invention is 2-8 days. For the same number of cycles, the aging time of the TCEEIA 415-2023 method is 4-16 days, which is twice that of the present invention.

[0050] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0051] Although exemplary embodiments of the invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the invention without departing from the central concepts of the invention described herein. Therefore, the invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the invention.

Claims

1. A method for testing the compatibility of lubricating oil with motor materials, characterized in that: Includes the following steps: Add an appropriate amount of lubricating oil sample to the sealed container, place the oil-cooled motor material to be tested into the sealed container, and completely immerse it below the surface of the lubricating oil. Fill the sealed container with oxygen and pressurize it to the test state; Activate the magnetic stirrer and place the sealed container in a high-temperature chamber preheated to 155℃±2℃. The time for heating the contents of the container to 155±2℃ should not exceed 30 minutes. After maintaining the temperature for 40 hours, remove the sealed container and transfer it to a low-temperature chamber that has been cooled to -45±2℃. The time for cooling the contents of the container to -45±2℃ should not exceed 30 minutes. Maintain the temperature for 8 hours. This completes one cycle. Increase the number of cycles as needed. After the constant temperature period is over, place the sealed container in room temperature to cool to room temperature, vent the air, open the sealed lid, and take out the sample for testing.

2. The method for testing the compatibility of lubricating oil and motor materials as described in claim 1, characterized in that: After the lubricating oil is added to the sealed container, the oil level should be below 2 / 3 of the container's height, and at least 1 / 3 of the container should be filled with air.

3. The method for testing the compatibility of lubricating oil and motor materials as described in claim 1, characterized in that: Under test conditions, the internal pressure of the sealed container is increased to above standard atmospheric pressure but less than 830 kPa.

4. The method for testing the compatibility of lubricating oil and motor materials as described in claim 1, characterized in that: The sealed container includes a container body, a sealing cap, and a magnetic stirrer. The inner cavity of the container body is provided with a motor material fixing frame, the top of the container body is equipped with a sealing cap, and the bottom is provided with a magnetic stirrer. The sealing cap is provided with an air supply pipe, and the air supply pipe is provided with an air filling valve.

5. The method for testing the compatibility of lubricating oil and motor materials as described in claim 4, characterized in that: A pressure sensor is installed on the upper part of the sealed container.

6. The method for testing the compatibility of lubricating oil and motor materials as described in claim 4, characterized in that: During the oxygen filling and air purging process, oxygen is blown into the sealed container to increase the internal air pressure. After filling is complete, the filling valve is switched from the filling state to the venting state to release the gas in the sealed container and depressurize, completing one filling and venting cycle. Then, the filling valve is switched back to the filling state, and the filling and venting operation is repeated until the oxygen completely replaces the air. Finally, the filling valve is switched back to the filling state to pressurize the sealed container to the test state.

7. The method for testing the compatibility of lubricating oil and motor materials as described in claim 4, characterized in that: The sealing cover is connected to an air inlet pipe and an air outlet pipe. The air inlet pipe is equipped with an air inlet switch, and the air outlet pipe is equipped with a one-way valve and an air outlet switch.

8. The method for testing the compatibility of lubricating oil and motor materials as described in claim 7, characterized in that: Connect the end of the air inlet pipe to an oxygen cylinder and introduce oxygen into the sealed container. As a large amount of oxygen is poured into the sealed container, the air inside the sealed container is discharged from the exhaust pipe, and the oxygen completely replaces the air inside the sealed container.

9. The method for testing the compatibility of lubricating oil and motor materials as described in claim 1, characterized in that: The magnetic stirrer operates at a speed of less than 2000 rpm.

10. The method for testing the compatibility of lubricating oil and motor materials as described in claim 1, characterized in that: The top of the sealed container is provided with a flange, and an annular groove is opened on the flange to assemble a polytetrafluoroethylene sealing ring. An assembly hole is also provided to connect the sealing cover; the sealing cover is installed on the top of the sealed container by bolts.

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