Method for measuring gas internal leakage of pressure accumulator at high and low temperatures

Abstract

The invention discloses a method for measuring the gas internal leakage of a pressure accumulator at high and low temperatures, which comprises the following steps of: pressurizing and decompressing a liquid cavity of a test pressure accumulator through an accompanying test pressure container to ensure that gas leaked from the test pressure accumulator is stored in a pipeline; then, gas in the gas cavity of the tested pressure accumulator is leaked to the liquid cavity, at the moment, the volume of oil in the liquid cavity is increased, the liquid level of a tubular column communicated with the liquid cavity rises, and the gas internal leakage amount is obtained. According to the invention, the gas internal leakage amount of the pressure accumulator in the working process, especially in the high-temperature environment, can be measured. The method has the advantages of being simple, efficient, high in operability, accurate in measurement and free of special limitation requirements, and has good practicability.

Description

Technical Field

[0001] This invention belongs to the technical field of plunger-type accumulator testing in aviation and aerospace, specifically relating to a method for determining the internal leakage of gas in an accumulator under high and low temperatures. Background Technology

[0002] Accumulators are widely used as important accessories in aircraft hydraulic systems, and their main functions include the following: (1) Energy storage: When the load in the system is not working, the accumulator can store part or all of the hydraulic energy output by the hydraulic pump. When the system needs energy, the accumulator can release the stored energy again. In a short time, a large amount of hydraulic oil with a certain pressure can be released to supplement the peak flow, thereby reducing the power of the hydraulic pump in the system and making the system energy utilization more reasonable. When the hydraulic pump fails, the accumulator can be used as an emergency energy source for emergency braking, emergency deployment of landing gear and flaps, etc. The oil stored in the accumulator can also be used to compensate for changes in oil volume caused by temperature, leakage, etc.

[0003] (2) Absorbing pulse pressure; In energy systems, accumulators are used to absorb pressure pulsations from hydraulic pumps.

[0004] (3) Absorbing impact pressure; In hydraulic systems, accumulators are used to absorb impact pressure generated when the fluid velocity changes drastically.

[0005] (4) Achieving dynamic stability; In hydraulic servo systems, accumulators are used to reduce the system's natural frequency, increase the damping coefficient, and enhance stability margin. Accumulators can be classified into three types according to their energy storage methods: gravity-type, spring-type, and pneumatic-type. Gravity-type and spring-type accumulators are simple in structure and easy to manufacture, but they have small capacity and present issues with weight, volume, and installation; therefore, they are generally not used in modern aircraft hydraulic systems. Pneumatic accumulators can be further classified into three types based on their structural form: cylinder-type, piston-type, and capsule-type. Cylinder-type accumulators, due to direct contact between gas and liquid, are prone to causing gas to dissolve in the liquid or enter the system, affecting the performance of the hydraulic system; therefore, they are generally not used. The commonly used accumulator on aircraft is the cylindrical piston-type accumulator.

[0006] A cylindrical piston-type accumulator divides the accumulator into a liquid chamber and a gas chamber via a piston and a seal mounted on it. The gas chamber is pre-filled with high-pressure nitrogen, while the liquid chamber is connected to a hydraulic system. Pressurizing and depressurizing the liquid chamber pushes the piston in a reciprocating linear motion within the outer cylinder, thus compressing and releasing the gas in the gas chamber, achieving energy storage and release. During the accumulator's operation, gas leaks into the liquid chamber through a movable seal. Measuring the amount of gas leakage during accumulator operation is of significant importance and provides guidance for the study of the accumulator's movable seal. Summary of the Invention

[0007] The purpose of this invention is to provide a method for measuring the internal leakage of gas in an accumulator under high and low temperatures, aiming to solve the problem that there is no effective method for measuring the internal leakage of gas in the gas chamber during the working cycle of existing plunger-type accumulators, especially when operating in high and low temperature environments.

[0008] This invention is mainly achieved through the following technical solutions: A method for determining the internal leakage of gas in an accumulator at high and low temperatures involves pressurizing and depressurizing the liquid chamber of the test accumulator using a test pressure vessel to ensure that the leaked gas is stored in the pipeline. Then, the gas in the gas chamber of the test accumulator is allowed to leak into the liquid chamber. At this time, the volume of oil in the liquid chamber increases, causing the liquid level in the tubing connected to the liquid chamber to rise, thus obtaining the internal leakage of gas.

[0009] To better realize the present invention, the following steps are further included: Step S1: Place the test accumulator and the accompanying pressure vessel in the test chamber and perform pretreatment to remove residual gas from the liquid chamber; Step S2: Connect the hydraulic tubing to the liquid chamber of the test accumulator, adjust the test chamber temperature to the required high or low temperature, and after the temperature of the gas chamber of the test accumulator stabilizes at the required high or low temperature, disconnect the hydraulic tubing from the liquid chamber of the test accumulator and record the liquid level value of the hydraulic tubing. Step S3: Connect the test accumulator and the test pressure vessel, adjust the test bench pressure to the rated working pressure, and pressurize and depressurize the liquid chamber of the test pressure vessel. Pressurize and depressurize the test accumulator through the test pressure vessel to make it work. Step S4: Stabilize the gas chamber temperature of the test accumulator to the required high or low temperature, connect the hydraulic tubing to the liquid chamber of the test accumulator, check the change in the liquid level of the tubing, and record the liquid level value after the liquid level of the tubing stabilizes. Step S5: Obtain the internal leakage of gas in the test accumulator by recording the liquid level changes in steps S3 and S4.

[0010] To better realize the present invention, the preprocessing in step S1 further includes the following steps: Step S11: At room temperature, fill the gas chamber of the test accumulator with nitrogen gas at the required pressure and then seal it; Step S12: Discharge the residual gas from the test accumulator liquid chamber, the test pressure vessel, and the pipeline.

[0011] To better realize the present invention, in step S12, based on the test bench control, the oil pressure of the test accumulator and the test pressure vessel are alternately increased and decreased to discharge the residual gas in the test accumulator liquid chamber, the test pressure vessel and the pipeline.

[0012] To better realize the present invention, in step S12, the test bench is connected to the liquid chamber of the test accumulator through the first branch, and a control valve group is provided on the first branch; the test bench is connected to the liquid chamber of the test pressure vessel through the pipeline interface 1.

[0013] To better realize the present invention, further, in step S2, before connecting the hydraulic tubing to the liquid chamber of the test accumulator, the hydraulic tubing is calibrated: The test bench is pressurized to allow the oil in the pipeline to enter the hydraulic column until the hydraulic column level no longer changes, at which point the pressure on the test bench is released.

[0014] The beneficial effects of this invention are as follows: This invention can measure the internal gas leakage of an accumulator during operation, especially in high-temperature environments. It is simple, efficient, easy to operate, accurate, and has no special limitations, making it widely applicable for measuring internal gas leakage during accumulator operation. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the control principle of the method for measuring the internal leakage of gas in an accumulator at high and low temperatures according to the present invention.

[0016] Wherein: 1-Test accumulator, 2-Accompanying pressure vessel, 3-Hydraulic tubing, 4-First control valve, 5-Second control valve, 6-Third control valve. Detailed Implementation

[0017] Example 1: A method for determining the internal leakage of gas in an accumulator at high and low temperatures, such as Figure 1 As shown, a measurement system is used to test and evaluate the internal leakage of gas. The measurement system includes: a test pressure vessel 2 for pressurizing the test accumulator 1; an oil tubing column for displaying the gas leakage value; and a first control valve 4, a second control valve 5, and a third control valve 6 for opening and closing the hydraulic lines. The liquid chamber of the test accumulator 1 and the test pressure vessel 2 are connected by pipelines. Closing the second control valve 5 and the third control valve 6 forms a closed chamber, and closing the first control valve 4 also forms a closed chamber. The test pressure vessel 2 pressurizes and depressurizes the test accumulator 1, ensuring that leaked gas from the test accumulator 1 is stored in the pipeline. Gas leakage from the gas chamber of the test accumulator 1 into the liquid chamber causes an increase in the oil volume in the liquid chamber and a rise in the oil level in the tubing column.

[0018] The determination method specifically includes the following steps: (1) At room temperature, nitrogen gas of the required pressure value is filled into the gas chamber of the test accumulator 1 and then sealed. The liquid chamber of the test accumulator 1, the test pressure vessel 2, the oil tubing and the test bench pipeline interface 2 are connected by pipelines. The pipelines are equipped with a first control valve 4, a second control valve 5 and a third control valve 6 to control the opening and closing of the pipelines. The test pressure vessel 2 is connected to the test bench pipeline interface 1. The test accumulator 1 and the test pressure vessel 2 are placed in the test chamber.

[0019] (2) Open the first control valve 4 and the second control valve 5, close the third control valve 6, adjust the pressure of the test bench to be greater than the charging pressure of the test accumulator 1, and alternately apply and unapply oil pressure to the pipeline interface 1 and the pipeline interface 2 to discharge the residual gas in the test accumulator liquid chamber, the accompanying pressure vessel 2 and the pipeline.

[0020] (3) When the pipeline interface 2 is under pressure, close the pipeline interface 1, close the second control valve 5, and slowly open the third control valve 6 to allow the oil in the pipeline to enter the liquid column until the liquid level no longer changes, and then release the pressure of the test bench.

[0021] (4) Keep the first control valve 4 and the third control valve 6 open, close the second control valve 5, adjust the temperature of the test chamber to the required high or low temperature, and after the temperature of the gas chamber of the test accumulator 1 stabilizes to the required high or low temperature, close the third control valve 6 and record the liquid column level value.

[0022] (5) Adjust the pressure of the test bench to the rated working pressure, close the first control valve 4, pressurize and depressurize the pipeline interface 1, and pressurize and depressurize the test accumulator 1 through the test pressure vessel 2 to make it work. After the test, the gas chamber temperature of the test accumulator 1 is stabilized again to the required high or low temperature. Open the first control valve 4, and then slowly open the third control valve 6 to check the change of the liquid level in the tubing. Record the liquid level value after the liquid level in the tubing stabilizes.

[0023] (6) The internal leakage of gas in the test accumulator 1 can be obtained by the change of liquid level before and after.

[0024] This invention can measure the internal gas leakage of an accumulator during operation, especially in high-temperature environments. It is simple, efficient, easy to operate, accurate, and has no special limitations, making it widely applicable for measuring internal gas leakage during accumulator operation.

[0025] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method of measuring the amount of gas leakage from a pressure accumulator at high and low temperatures, characterized by, The pressure vessel (2) pressurizes and depressurizes the liquid chamber of the test accumulator (1) to ensure that the gas leaking from the test accumulator (1) is stored in the pipeline. Then, the gas in the gas chamber of the test accumulator (1) leaks into the liquid chamber. At this time, the volume of the oil in the liquid chamber increases, causing the liquid level of the tubing connected to the liquid chamber to rise, and the amount of gas leakage is obtained.

2. The method of claim 1, wherein Includes the following steps: Step S1: Place the test accumulator (1) and the accompanying pressure vessel (2) in the test chamber and perform pretreatment to remove residual gas from the liquid chamber; Step S2: Connect the hydraulic tubing (3) to the liquid chamber of the test accumulator (1), adjust the temperature of the test chamber to the required high or low temperature, and after the temperature of the gas chamber of the test accumulator (1) stabilizes to the required high or low temperature, disconnect the hydraulic tubing (3) from the liquid chamber of the test accumulator (1) and record the liquid level value of the hydraulic tubing (3). Step S3: Connect the test accumulator (1) and the test pressure vessel (2), adjust the test bench pressure to the rated working pressure, and pressurize and depressurize the liquid chamber of the test pressure vessel (2). Pressurize and depressurize the test accumulator (1) through the test pressure vessel (2) to make it work. Step S4: Re-stabilize the gas chamber temperature of the test accumulator (1) to the required high or low temperature, connect the hydraulic tubing (3) to the liquid chamber of the test accumulator (1), check the change in the tubing level, and record the level value after the liquid level in the tubing stabilizes. Step S5: The internal leakage of gas in the test accumulator (1) is obtained by recording the liquid level changes in steps S3 and S4.

3. The method of claim 2, wherein the method is characterized by: In step S1, the preprocessing includes the following steps: Step S11: At room temperature, fill the gas chamber of the test accumulator (1) with nitrogen gas at the required pressure value and then seal it; Step S12: Discharge the residual gas in the test accumulator liquid chamber, the test pressure vessel (2), and the pipeline.

4. The method of claim 3, wherein the method is characterized by: In step S12, based on the test bench control, the oil pressure of the test accumulator (1) and the test pressure vessel (2) is alternately increased and decreased to discharge the residual gas in the test accumulator liquid chamber, the test pressure vessel (2) and the pipeline.

5. The method of claim 4, wherein the method is characterized by: In step S12, the test bench is connected to the liquid chamber of the test accumulator (1) through the first branch, and a control valve group is provided on the first branch; the test bench is connected to the liquid chamber of the test pressure vessel (2) through the pipeline interface 1.

6. The method of claim 2, wherein the method is characterized by: In step S2, before connecting the hydraulic string (3) to the liquid chamber of the test accumulator (1), the hydraulic string (3) is calibrated: The test bench is pressurized to allow the oil in the pipeline to enter the hydraulic column (3) until the liquid level in the hydraulic column (3) no longer changes, and then the pressure of the test bench is released.

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