Aviation Turbine Lubricating Oil Thermal Stability and Corrosion Test Ultimate Vacuum Device and Its Method

Abstract

The present invention relates to the technical field of aviation oil product testing, and discloses an extreme vacuum device and method for a thermal stability corrosion test of aviation turbine lubricating oil. The device includes a vacuum pump, a vacuum gauge, a first control valve, a second control valve, and a water bath arranged in sequence; a first vacuum tube is connected between the vacuum pump and the vacuum gauge; a second vacuum tube is connected between the vacuum gauge and the first control valve; a vacuum clamp is connected between the first control valve and the second control valve; the second control valve is communicated with the inside of the test tube through a third vacuum tube; the water bath is a constant temperature water bath; the test tube includes a capillary tube body and an oxidation tube body integrally connected; the third vacuum tube is communicated with the capillary tube body. The present invention can construct an extreme vacuum environment in the test tube, with a high vacuum degree and stable maintenance.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation oil product testing, and particularly to an extreme vacuum device and method for a thermal stability and corrosion test of aviation turbine lubricating oil. Background Art

[0002] To ensure the safe and efficient operation of an aviation turbine engine, it is necessary to rely on a lubrication system to continuously supply stable aviation turbine lubricating oil to the key friction parts of the engine. This lubricating oil can not only effectively reduce friction and wear between components, but also efficiently conduct and carry away the high temperature generated by fuel combustion, helping to maintain the engine within a suitable operating temperature range, thereby ensuring its long-term stable operation. During the cyclic use of aviation turbine lubricating oil, it will undergo a series of dynamic changes such as heat absorption, temperature rise, chemical oxidation, and subsequent cooling. These processes may cause problems such as evaporation loss of the lubricating oil, formation of carbon deposits, or corrosion of metal surfaces. Therefore, aviation turbine lubricating oil must possess highly thermal stability, antioxidant properties, and good chemical inertness, etc., to cope with extreme working conditions. To evaluate whether an aviation turbine lubricating oil meets the usage requirements, it is usually necessary to comprehensively test and evaluate a number of key performance indicators such as its thermal stability, antioxidant capacity, and corrosiveness according to international and industry standards.

[0003] However, at present, few domestic researchers or research institutions can conduct qualified and accurate tests and evaluations on these key performance indicators, and there are many technical barriers. Taking the performance index tests of the thermal stability and corrosiveness of aviation turbine lubricating oil as an example, in internationally recognized airworthiness standards, both of these two indicators need to be carried out in a specific vacuum environment to exclude the influence of air and simulate the actual working conditions. On the surface, it is not difficult to create a vacuum condition. However, in the actual test environment, since the test conditions also include an extreme high temperature (close to 300 °C), an extremely long continuous test period (96 hours or a longer test period), and strict variable control, etc., these factors put more stringent requirements on the vacuum condition. If the vacuum purity is insufficient or cannot be maintained, it will directly affect the test quality and pose a safety risk. Summary of the Invention

[0004] The present invention aims to provide an extreme vacuum device and method for a thermal stability and corrosion test of aviation turbine lubricating oil, which can construct an extreme vacuum environment in the test tube with high vacuum degree and can be stably maintained.

[0005] To achieve the above object, the present invention provides the following basic solutions.

[0006] Solution 1

[0007] Aero-turbine lubricating oil thermal stability and corrosion test ultimate vacuum device, comprising a vacuum pump, a vacuum gauge, a first control valve, a second control valve and a water bath arranged in sequence; a first vacuum tube is connected between the vacuum pump and the vacuum gauge; a second vacuum tube is connected between the vacuum gauge and the first control valve; a vacuum clamp is connected between the first control valve and the second control valve; the second control valve is communicated with the inside of the test tube through a third vacuum tube; the water bath is a constant temperature water bath;

[0008] The test tube comprises a capillary tube body and an oxidation tube body which are integrally connected; the third vacuum tube is communicated with the capillary tube body.

[0009] Furthermore, both the first vacuum tube and the second vacuum tube are high-vacuum bellows; the third vacuum tube is a thick-walled silica gel tube.

[0010] Furthermore, the first control valve is a high-vacuum ball valve; the second control valve is a double-tower head ball valve.

[0011] Furthermore, the temperature of the constant temperature water bath is set to 80°C ± 1°C.

[0012] Furthermore, the lengths of the first vacuum tube and the second vacuum tube are set to 100 cm ± 10 cm; and fastening rings are provided at both ends of the first vacuum tube and both ends of the second vacuum tube.

[0013] Scheme Two

[0014] Usage method of the aero-turbine lubricating oil thermal stability and corrosion test ultimate vacuum device, using the aero-turbine lubricating oil thermal stability and corrosion test ultimate vacuum device as described in Scheme One to conduct the aero-turbine lubricating oil thermal stability and corrosion test; including the following steps:

[0015] Step 1, assemble the aero-turbine lubricating oil thermal stability and corrosion test ultimate vacuum device; and pre-add the oil sample to be tested into the test tube;

[0016] Step 2, tilt and statically place the test tube; and turn on the vacuum pump, the first control valve and the second control valve, and observe the state of the oil sample in the test tube; within the first preset time, if the state of the oil sample shows no bubbles generated, then proceed to the next step, otherwise, determine the test tube as a waste tube, replace the test tube and repeat this step until within the first preset time, the state of the oil sample shows no bubbles generated;

[0017] Step 3, start the constant temperature water bath and set its temperature to the target temperature, and statically place the test tube in the constant temperature water bath;

[0018] Step 4, observe the value of the vacuum gauge, when the value of the vacuum gauge is lower than the reference value, turn off the second control valve, the first control valve and the vacuum pump in sequence;

[0019] Step 5: Transfer the test tube and heat-seal the test tube at a high temperature at the capillary tube.

[0020] Step 6: Determine the heat-sealing state of the test tube. After the heat-sealing state meets the standard, transfer the test tube to a high-temperature bath for performance testing.

[0021] Furthermore, in the second half of the first preset time, keep shaking the test tube; and within the first preset time, if specific bubble characteristics appear, directly determine the test tube as a waste tube; the specific bubble characteristics include linear small bubbles; the small bubbles refer to bubbles with a diameter of 30μm to 50μm.

[0022] Furthermore, in Step 5, when transferring the test tube, transfer it together with the second control valve and the third vacuum tube.

[0023] Furthermore, in Step 5, the heat-sealing position of the test tube is selected at a distance of 5 cm to 8 cm from the top of the nozzle of the oxidation tube body; the width of the heat-sealing position is set to 1 cm to 1.5 cm; the heat-sealing thickness is set to 3 cm; the heat-sealing temperature of the high-temperature heat-sealing is set to 820°C to 850°C.

[0024] Furthermore, in Step 6, the qualified heat-sealing state means that the heat-sealing mouth has an inward concave feature, and the depth of the concave feature is 1.5 mm to 2 mm.

[0025] The working principle and advantages of the present invention are as follows:

[0026] The extreme vacuum device and method for the thermal stability and corrosion test of aviation turbine lubricating oil of the present invention can create an extreme vacuum environment in the test tube, with a high vacuum degree and stable maintenance. The key points are as follows:

[0027] This solution constructs a new extreme vacuum device using existing devices and provides a new and more reliable path for constructing vacuum conditions for the thermal stability and corrosion test of aviation turbine lubricating oil. First, the extreme vacuum device of this solution is connected to the inside of the test tube one by one, which can achieve targeted vacuum pumping, accurately ensure that the vacuum degree in the test tube meets the standard, and will not affect the rest of the test operations. Compared with the existing test vacuum pumping device, for example, the patent with the publication number CN211577022U discloses a device for measuring the thermal stability and corrosion of aviation turbine engine lubricating oil, in which the vacuum component used is to pump the vacuum of the overall environment where the test pool is located. Although this method is efficient, its accuracy is low, it cannot ensure that the vacuum degree in the test pool is absolutely up to standard, it cannot accurately know the pressure in the test pool, and it is not convenient to perform subsequent test operations on the test pool.

[0028] However, this solution does not have such problems. More importantly, this solution can perfectly meet the standard requirements, ensuring that the subsequent test results have practical reference value. In the requirements of aviation standards for the determination tests of the thermal stability and corrosivity of aviation turbine engine lubricating oil, for a completely sealed test tube, it is required that the absolute pressure inside is less than 1.3 Pa to form a standard test environment. Otherwise, it will lead to test failure or make the test results unreliable and lack credibility. First, because aviation turbine lubricating oil needs to maintain its performance in a high-altitude and low-pressure environment during actual application. Second, because if there is residual oxygen in the test tube (insufficient vacuum), during the test of thermal stability, when the lubricating oil contacts oxygen at high temperature, an oxidation reaction will occur, generating by-products such as carbon deposits and gums. These reactions may cover up the thermal decomposition characteristics of the oil itself, resulting in inaccurate results. During the test of corrosivity, it will make it difficult to fully exclude the corrosion effect of environmental gases on the metal test piece and is prone to increasing complex side reactions, leading to inaccurate results. The vacuum device provided by this solution can accurately measure and stably maintain the required vacuum environment, helping to ensure that the thermal stability and corrosivity tests only reflect the behavior of the oil under pure thermodynamic or its own chemical characteristics, and ensuring that the test results are reliable and have credibility.

[0029] Secondly, this solution optimizes the connection methods and layouts of various components, enabling the construction of a stable vacuum pumping environment and a stable vacuum degree calibration environment. The overall system construction method is simple, and the structure is concise, capable of achieving high-efficiency vacuum pumping. Among them, first, the selection of each component fits the high-vacuum scenario, with extremely high reliability and stability, and can meet the continuous vacuum pumping work requirements during the thermal stability and corrosivity tests of aviation turbine lubricating oil. Second, the layout of each component is special. Instead of simply using pipelines and valve bodies to connect to the vacuum pump, multi-layer pipelines, multi-layer valve bodies and vacuum gauges are set up to construct a stable vacuum pumping route. Through the setting of two-layer valve bodies, independent control, local isolation and double protection are achieved, and it is convenient to independently disassemble the test tube without affecting the test process. Through the setting of equal-length long corrugated pipelines at both ends of the vacuum gauge, the air pressure environment at both ends of the vacuum gauge is stabilized and balanced, and the resistance of the vacuum gauge to external fluctuations can be enhanced, which helps to improve the measurement accuracy of the vacuum gauge and achieve absolutely accurate and reliable vacuum degree measurement.

[0030] Furthermore, the device structure of this solution supports partial removal, that is, it supports the transfer together with the second control valve and the third vacuum tube. With this setting, the second control valve and the third vacuum tube can ensure that the test tube maintains a stable vacuum degree during the transfer process and subsequent high-temperature melting and sealing processes.

[0031] Second, this solution fills the defect in the construction of the vacuum condition in the thermal stability corrosion test of aviation turbine lubricating oil, and can greatly improve the success rate and efficiency of the thermal stability corrosion test of aviation turbine lubricating oil. Compared with the existing test methods, for example, the patent with the publication number CN116754750A discloses a performance test device and method for aviation lubricating oil. Although this solution gives complete test operation guidance, it does not give specific vacuum pumping operation guidelines, and the vacuum pumping effect cannot be confirmed. Moreover, the vacuum pumping method it adopts will actually damage the subsequent seal quality and cause the risk of tube explosion (for example, if the vacuum is maintained during sealing, it will interfere with the temperature distribution at the sealing position and is easy to form bubbles, affecting the uniformity and quality of the seal).

[0032] This solution provides precise vacuum pumping guidance for the thermal stability corrosion test of aviation turbine lubricating oil, can fully confirm the vacuum pumping effect and maintain the vacuum effect, and will not affect the seal quality. This solution observes the state of the oil sample in stages, uses bubbles as an obvious feature to verify the gas environment in the test tube, can accurately judge the vacuum degree in the test tube, and timely verify whether the airtightness of the tube body meets the requirements. While ensuring the vacuum purity meets the standard, it helps to reduce the risk of tube explosion caused by the quality of the tube body or the seal quality in the subsequent process (if the vacuum degree in the test tube cannot be maintained after being sealed, there is residual pressure or pressure relief, which will cause the oxidation tube to burst, affecting the test process and causing safety risks). Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the device for the extreme vacuum device and method of the thermal stability corrosion test of aviation turbine lubricating oil according to the embodiment of the present invention.

[0034] The marks in the attached drawings of the specification include: test bench 1, vacuum pump 2, first vacuum tube 3, iron stand 4, vacuum gauge 5, metal three-way fitting 6, second vacuum tube 7, first control valve 8, second control valve 9, third vacuum tube 10, vacuum clamp 11, test tube 12, constant temperature water bath 13. Detailed Description of the Invention

[0035] The following is a more detailed description through specific embodiments:

[0036] The embodiment is basically as shown in the attached Figure 1 figures: The extreme vacuum device for the thermal stability corrosion test of aviation turbine lubricating oil includes a vacuum pump 2, a vacuum gauge 5, a first control valve 8, a second control valve 9, and a water bath successively arranged on a test bench 1.

[0037] A first vacuum tube 3 is connected between the vacuum pump 2 and the vacuum gauge 5; a second vacuum tube 7 is connected between the vacuum gauge 5 and the first control valve 8; a vacuum clamp 11 is connected between the first control valve 8 and the second control valve 9; the second control valve 9 and the inside of the test tube 12 are connected through a third vacuum tube 10.

[0038] The test tube 12 includes a capillary tube body and an oxidation tube body connected integrally; the third vacuum tube 10 is connected to the capillary tube body. In this embodiment, the test tube 12 is made of borosilicate glass, which has a low expansion rate, good chemical corrosion resistance and thermal shock resistance, and can be adapted to the aviation oil product test environment with a long test cycle and under high temperature conditions.

[0039] Specifically, the vacuum pump 2 is a bipolar rotary vane vacuum pump 2, whose pumping speed is not less than 4³ / h, the ultimate vacuum pumping pressure is not higher than 0.05 Pa, and it has extremely high reliability and stability, which can meet the continuous vacuum pumping work requirements during the aviation turbine lubricating oil thermal stability corrosion test.

[0040] An iron stand 4 is also provided on the test bench 1, and the vacuum gauge 5 is installed on the iron stand 4 to keep its position stable. The vacuum gauge 5 is a digital display vacuum gauge 5, and its measurement range is ~1 Pa, and the accuracy is as high as 0.05 Pa. Through the vacuum gauge 5, the vacuum degree reached by the device can be accurately measured and visually displayed, which can provide an objective and reliable reference for vacuum condition verification.

[0041] Both the first vacuum tube 3 and the second vacuum tube 7 are high-vacuum bellows; the third vacuum tube 10 is a thick-walled silicone tube, and the thickness of the thick-walled silicone tube is not less than 2 mm. The lengths of the first vacuum tube 3 and the second vacuum tube 7 are set to 100 cm ± 10 cm; and fastening rings are provided at both ends of the first vacuum tube 3 and both ends of the second vacuum tube 7 to further enhance the airtightness of the device. The fastening rings are stainless steel vacuum clamps.

[0042] Among them, the high-vacuum bellows is a flexible connector specially designed for high-vacuum environments, mainly used for pipeline connection in vacuum systems to achieve relative movement between components or compensate for installation deviations. It has good sealing performance and strong corrosion resistance. Selecting this pipeline for the first vacuum tube 3 and the second vacuum tube 7 can ensure good airtightness under extremely high vacuum conditions, prevent external gas from infiltrating or internal gas from leaking, and can adapt to different working environments. The thick-walled silicone tube is a hose made of high-quality silicone rubber, which has good heat resistance, corrosion resistance, flexibility and elasticity, and can cooperate well with the test tube 12.

[0043] Furthermore, in the present embodiment, the lengths of the first vacuum tube 3 and the second vacuum tube 7 are both set to 100 cm; this length design takes into special consideration the ergonomics during the test operation, so that the test personnel can stably hold the vacuum tube and the test tube 12 when subsequently transferring the test tube 12, and because the pipe length is moderate, the pipe is not prone to dragging during the transfer process, which helps to maintain the stability of the internal vacuum environment during the transfer of the test tube 12.

[0044] The first vacuum tube 3, the second vacuum tube 7 and the vacuum gauge 5 are connected by a metal tee 6. In addition, the first vacuum tube 3 and the second vacuum tube 7 of relatively equal length are connected to the two ends of the vacuum gauge 5. Firstly, the air pressure environment at both ends of the vacuum gauge 5 can be balanced and stabilized; secondly, the bellows have good vibration reduction performance and flexible buffering effect, which can relatively isolate the vacuum gauge 5 from the vacuum pump 2, balance the vibration, maintain the mechanical stability of the entire device, and help improve the measurement accuracy of the vacuum gauge 5; thirdly, the bellows of equal length at both ends can ensure that the gas flows more evenly when entering and leaving the vacuum gauge 5, reduce turbulence and eddy current phenomena, and improve the accuracy of measurement; fourthly, the flexibility and compressibility of the bellows help to maintain the pressure balance of the system under different pressure conditions and avoid measurement errors caused by pressure fluctuations; fifthly, the bellows of equal length can make installation more convenient, and can more easily adjust and calibrate the positions of various components to ensure the overall performance of the system.

[0045] The first control valve 8 is a high vacuum ball valve. In this embodiment, a KF16 stainless steel ball valve is selected, which is suitable for high vacuum environment and has extremely high sealing performance; the second control valve 9 is a double pagoda head ball valve, which has a good sealing effect, and pagoda joints are used at both ends. This type of joint is easy and quick to install, can be connected and disassembled without tools, and can achieve rapid disassembly and assembly with other components. The pressure control range of the two ball valves is 0.1MPa~1MPa, and the distance between the two ball valves is 15mm. Here, two ball valves are set for sealing control. First, independent control and local isolation can be achieved, which is convenient for independently splitting the test tube 12; second, the two ball valves can provide double protection. Even if one of the ball valves fails, the other ball valve can still maintain the vacuum degree of the system to ensure the safe operation of the system.

[0046] The water bath is a constant temperature water bath 13; the temperature of the constant temperature water bath 13 is set to 80°C±1°C.

[0047] Here, if the water bath temperature is too high, the oil sample (specifically aviation lubricant) in the test tube 12 will undergo oxidation reaction, affecting the test results; in addition, the kinematic viscosity of the lubricant at 100°C is 5 , at 80℃, the kinematic viscosity is 8 -12 , it has a relatively small viscosity and better corresponding fluidity. In addition, lubricating oil also has an important index, namely the air release value, which means that lubricating oil contains a certain amount of air at room temperature; when a negative pressure is drawn, the smaller the viscosity, the easier it is to release the air in the lubricating oil, so that the air can be fully evacuated; therefore, choosing a temperature point where the lubricating oil is not oxidized and has a smaller viscosity is very important for creating an absolute vacuum environment.

[0048] In view of this, in this embodiment, the temperature is set to 80°C ± 1°C, which can ensure that the test tube 12 does not undergo an oxidation reaction in the short term, and the viscosity value of the oil in the tube is also relatively small, which is suitable for short-term rapid degassing.

[0049] This embodiment also provides a method for using an extreme vacuum device for aero-turbine lubricating oil thermal stability and corrosion test, which uses the extreme vacuum device for aero-turbine lubricating oil thermal stability and corrosion test as described above; it includes the following steps:

[0050] Step 1, assemble the extreme vacuum device for aero-turbine lubricating oil thermal stability and corrosion test; and pre-add the oil sample to be tested in the test tube 12.

[0051] Specifically, when assembling the extreme vacuum device for aero-turbine lubricating oil thermal stability and corrosion test, first install the vacuum gauge 5 on the iron stand 4, then connect the first vacuum tube 3 and the second vacuum tube 7 at both ends, and connect the other end of the first vacuum tube 3 to the vacuum pump 2, connect the other end of the second vacuum tube 7 to the first control valve 8, and then connect the first control valve 8 and the second control valve 9. When adding the oil sample to the test tube 12, use a glass syringe to add 6 ml of the oil sample from the port of the capillary body of the test tube 12. Then use the third vacuum tube 10 to connect the second control valve 9 and the port of the capillary body of the test tube 12.

[0052] Step 2, tilt and statically place the test tube 12; and turn on the vacuum pump 2, the first control valve 8 and the second control valve 9, and observe the state of the oil sample in the test tube 12; within the first preset time, if the state of the oil sample shows no bubble generation, then perform the next step, otherwise, determine that the test tube 12 is a waste tube, replace the test tube 12 and repeat this step until within the first preset time, the state of the oil sample shows no bubble generation.

[0053] In the second half of the first preset time, keep shaking the test tube 12; here, the shaking frequency is 1 - 2 seconds / time, and the shaking time is greater than 10 min to fully remove the air in the oil sample.

[0054] Moreover, within the first preset time, if specific bubble characteristics appear in the oil sample, the test tube 12 is directly determined to be a waste tube; the specific bubble characteristics include linear small bubbles; the small bubbles refer to bubbles with a diameter of 30μm to 50μm. Linear means that multiple small bubbles are coherent into a linear shape. In this embodiment, the first preset time is set to 20 min.

[0055] In this step, by observing the state of the oil sample and using bubbles as the dominant feature to verify the gas environment in the test tube 12, the vacuum degree in the test tube 12 can be accurately judged, and whether the airtightness of the tube body meets the requirements can be verified in time, which helps to reduce the risk of tube explosion caused by the quality of the tube body in the follow-up.

[0056] Step 3: Start the constant temperature water bath 13 and set its temperature to the target temperature, and place the test tube 12 statically in the constant temperature water bath 13.

[0057] The target temperature is set to 80°C ± 1°C.

[0058] Preferably, after keeping the test tube 12 tilted and static in the constant temperature water bath 13 for 10 min, the test tube 12 is vibrated slightly within the second preset time until no bubbles are generated in the test tube 12. The second preset time is also set to 20 min. With such a setting, through the visually observable state of the oil sample, the vacuum degree inside the test tube 12 and the quality of the test tube 12 itself can be fully verified.

[0059] Step 4: Observe the value of the vacuum gauge 5. When the value of the vacuum gauge 5 is lower than the reference value, close the second control valve 9, the first control valve 8, and the vacuum pump 2 in sequence.

[0060] Specifically, the reference value is set to 1.3 Pa. When the value of the vacuum gauge 5 is lower than this reference value and remains stable within a certain time (such as 1 min to 2 min), it proves that a relatively high vacuum degree has been achieved in the test tube 12, meeting the vacuum standard required for the performance test. Then, closing the second control valve 9, the first control valve 8, and the vacuum pump 2 in sequence can keep the vacuum environment at the test tube 12 stable.

[0061] Step 5: Transfer the test tube 12 and heat-seal the test tube 12 at a high temperature from the capillary.

[0062] When transferring the test tube 12, transfer it in coordination with the second control valve 9 and the third vacuum tube 10. With such a setting, the continuity of the vacuum environment can be ensured during the transfer process, preventing external air from entering the system during the transfer process, and fully maintaining the vacuum state at the test tube 12.

[0063] When sealing the test tube 12, an oxyacetylene flame device is used to control the oxyacetylene flame to align with the sealing position for sealing. Specifically, the oxyacetylene flame device is arranged within 1m of the ultimate vacuum device, the height of the oxyacetylene flame is 200mm±50mm, and the temperature can reach 3100℃~3400℃. In this embodiment, the sealing temperature of the high-temperature sealing is set to 820℃~850℃. Under this temperature condition, it can ensure that the material of the test tube 12 is fully melted and maintains moderate fluidity (too low temperature may cause local non-melting, resulting in micropores or cracks; too high temperature may over-soften the material, resulting in deformation or too thin sealing), forming a uniform, seamless and stable sealing layer.

[0064] The sealing position of the test tube 12 is selected to be 5cm~8cm away from the top of the tube mouth of the oxidation tube body; the width of the sealing position is set to 1cm~1.5cm; the sealing thickness is set to 3cm. Under this sealing parameter condition, the sealing width and sealing thickness are appropriately set. Among them, the size setting of 5cm~8cm has sufficient sealing area, which can enhance the sealing performance and reduce the risk of leakage. It is also more convenient to put the test tube 12 into the metal constant temperature bath without affecting the structural stress at the interface between the small tube and the large tube; the size limits of 1cm~1.5cm and 3cm can ensure that the sealing thickness is not too large, and can ensure uniform heat distribution, high sealing quality, and not easy to explode the tube.

[0065] Step 6, determine the sealing state of the test tube 12, and after the sealing state meets the standard, transfer the test tube 12 to a high temperature bath for performance testing.

[0066] In this step, the fusion sealing state meets the standard, which means that the fusion sealing mouth has an inward concave feature, and the depth of the concave feature is 1.5mm~2mm. Here, because the capillary wall will soften during fusion sealing (high borosilicate glass melts under high heat), and at the same time, because the pressure environment inside the test tube 12 is less than 1.3Pa, under the influence of the external atmospheric pressure (101.3kpa), the fusion sealing mouth will be concave inward, so when the concave seal appears, it indicates that the fusion sealing of the test tube 12 is successful, and the pressure inside the test tube 12 meets the test safety requirements, and can be transferred to the high temperature bath.

[0067] Here, a high temperature constant temperature bath set at 274°C ± 1°C may be used, and a 96-hour performance test may be performed according to the test standard.

[0068] Using this solution, the total time from removing the test tube 12 from the vacuum system to completing the sealing (corresponding to step 5 to step 6) is , which can ensure the vacuum state in the test tube 12 to a great extent.

[0069] An extreme vacuum device and method for the thermal stability and corrosion test of aviation turbine lubricating oil provided by this embodiment can create an extreme vacuum environment in the test tube 12, with a high and stable vacuum degree. The overall device has relatively low assembly and usage costs, and has good economy and adaptability. Moreover, in actual test applications, our side used this vacuum device to complete 200 sets of thermal stability and corrosion determination tests for aviation turbine engine lubricating oil. During the test process, multiple test tubes 12 all experienced a strict temperature change environment (room temperature → 274°C high-temperature bath), but none of the test tubes 12 exploded. Thus, it can be seen that this device has strong reliability, and it also indirectly verifies the compliance and stability of the vacuum environment in the test tube 12. Compared with the previous method of directly connecting a pump to the test tube 12 to extract vacuum during testing, this solution can reduce the risk of test tube explosion from 2 - 5 times per 10 groups of tests to 0 times, with a significant effect.

[0070] The application effect of this solution is described below in combination with specific comparative examples:

[0071] Comparative Example 1: In the vacuum extraction stage of the existing thermal stability and corrosion test, a traditional air extraction device is used to directly extract air from the test tube 12 through a pipeline.

[0072] Comparative Example 2: On the basis of this solution, the first control valve 8 is not provided.

[0073] Comparative Example 3: On the basis of this solution, the second control valve 9 is not provided.

[0074] Comparative Example 4: On the basis of this solution, the multi-level pipeline is not provided.

[0075] Test tubes 12 are prepared respectively using the solutions of this embodiment and Comparative Examples 1 - 4, and six groups of thermal stability and corrosion tests are carried out on the premise that the remaining test conditions are the same. The test results are shown in Tables 1 and 2.

[0076] Table 1 Tube explosion results

[0077]

[0078] Table 2 Vacuum degree situation (the extreme vacuum degree that can be achieved inside the test tube)

[0079]

[0080] It can be seen from Tables 1 and 2 that in the six groups of tests, test tube explosions occurred in Comparative Examples 1 - 4, while no test tube explosion occurred in this embodiment; moreover, the extreme vacuum degrees that can be achieved in Comparative Examples 1 - 4 cannot meet the standard requirements, while this embodiment can meet the standard requirements and even has an improvement on the basis of meeting the standard.

[0081] Thus, it can be seen that the solution provided by this embodiment has obvious advantages, and the constructed vacuum environment meets the standards and can remain stable in the extreme test environment for a long time.

[0082] The above are only embodiments of the present invention. Common general knowledge such as specific structures and characteristics well known in the art is not described in detail here. Those of ordinary skill in the art know all the general technical knowledge in the technical field to which the invention pertains before the filing date or the priority date, can learn all the existing technologies in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, improve and implement this solution in combination with their own abilities. Some typical well-known structures or well-known methods should not become an obstacle for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, 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 implementation effect of the present invention and the practicality of the patent.

Claims

1. A limit vacuum device for the thermal stability and corrosiveness test of aviation turbine lubricating oil, characterized in that, It includes a vacuum pump, a vacuum gauge, a first control valve, a second control valve and a water bath pool arranged in sequence; a first vacuum tube is connected between the vacuum pump and the vacuum gauge; a second vacuum tube is connected between the vacuum gauge and the first control valve; the first vacuum tube and the second vacuum tube adopt bellows and are arranged at equal lengths relative to both ends of the vacuum gauge; a vacuum clamp is connected between the first control valve and the second control valve; the second control valve is communicated with the inside of the test tube through a third vacuum tube; the water bath pool is a constant temperature water bath pool. The test tube includes a capillary tube body and an oxidation tube body connected integrally; the third vacuum tube is communicated with the capillary tube body; the second control valve and the third vacuum tube are transferred together with the test tube during use.

2. The extreme vacuum device for the aviation turbine lubricating oil thermal stability and corrosion test according to claim 1, characterized in that, The third vacuum tube is a thick-walled silica gel tube, and the thickness of the thick-walled silica gel tube is not less than 2 mm.

3. The aviation turbine lubricating oil thermal stability and corrosion test ultimate vacuum device according to claim 1, characterized in that, The second control valve is a double-tower head ball valve.

4. The extreme vacuum device for the aviation turbine lubricating oil thermal stability and corrosion test according to claim 1, characterized in that, The temperature of the constant temperature water bath pool is set to 80°C ± 1°C.

5. The aviation turbine lubricating oil thermal stability and corrosion test ultimate vacuum device according to claim 2, characterized in that, The lengths of the first vacuum tube and the second vacuum tube are set to 100 cm ± 10 cm; and fastening rings are provided at both ends of the first vacuum tube and both ends of the second vacuum tube.

6. The method of using the ultimate vacuum device for the thermal stability corrosion test of aviation turbine lubricating oil is characterized in that, An aviation turbine lubricating oil thermal stability and corrosion test is carried out by using the aviation turbine lubricating oil thermal stability and corrosion test ultimate vacuum device according to any one of claims 1-5; it includes the following steps: Step 1, assemble the aviation turbine lubricating oil thermal stability and corrosion test ultimate vacuum device; and pre-add the oil sample to be tested into the test tube. Step 2, tilt and statically place the test tube; and turn on the vacuum pump, the first control valve and the second control valve, and observe the state of the oil sample in the test tube; within the first preset time, if the state of the oil sample shows no bubble generation, then perform the next step, otherwise, determine the test tube as a waste tube, replace the test tube and repeat this step until within the first preset time, the state of the oil sample shows no bubble generation. Step 3, start the constant temperature water bath pool and set its temperature to the target temperature, and statically place the test tube in the constant temperature water bath pool. Step 4, observe the value of the vacuum gauge, and when the value of the vacuum gauge is lower than the reference value, close the second control valve, the first control valve and the vacuum pump in sequence. Step 5, transfer the test tube, and heat-seal the test tube at a high temperature from the capillary; the heat-sealing temperature of the high-temperature heat-sealing is set to 820°C - 850°C. Step 6, determine the heat-sealing state of the test tube, and after the heat-sealing state meets the standard, transfer the test tube to a high-temperature bath for performance testing; the temperature of the high-temperature bath is set to 274°C ± 1°C.

7. The method for using the ultimate vacuum device for the thermal stability and corrosiveness test of aviation turbine lubricating oil according to claim 6, characterized in that In the second half of the first preset time, keep shaking the test tube; and within the first preset time, if specific bubble characteristics appear, directly determine the test tube as a waste tube; the specific bubble characteristics include linear small bubbles; the small bubbles refer to bubbles with a diameter of 30 μm - 50 μm.

8. The method for using the ultimate vacuum device for the aviation turbine lubricating oil thermal stability and corrosion test according to claim 6, characterized in that, In step 5, when transferring the test tube, transfer it together with the second control valve and the third vacuum tube.

9. The method of using the ultimate vacuum device for the aviation turbine lubricating oil thermal stability and corrosion test according to claim 6, characterized in that In step 5, the heat-sealing position of the test tube is selected to be 5 cm - 8 cm from the top of the pipe orifice of the oxidation tube body; the width of the heat-sealing position is set to 1 cm - 1.5 cm; the heat-sealing thickness is set to 3 cm.

10. The method for using the ultimate vacuum device for the thermal stability and corrosiveness test of aviation turbine lubricating oil according to claim 6, characterized in that In step 6, the qualified hermetic sealing state means that the hermetic seal has a concave feature facing inward, and the depth of the concave feature is 1.5 mm to 2 mm.

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