A brake system pollutant backflush verification test method

Abstract

The application belongs to the field of brake system test, and is a kind of brake system pollutant backwash verification test method. First, the oil sample in the brake device of the aircraft after continuous flight for a certain number of times is collected, the source of the pollutants in the oil sample is confirmed, then a pollutant backwash verification test bench is built, and a brake system sampling point is arranged on the pollutant backwash verification test bench, then the test pollutants are configured according to the parameters of the pollutants, and are added into the brake actuating cylinder; the test operation is carried out, the brake operation times when the oil backwash reaches the brake system sampling point are obtained, and whether the anti-pollution ability of the brake system can meet the requirements can be judged. The relationship between the factors such as the length of the brake system pipeline, the vertical drop between the accessories and the brake device and the pollutant backwash condition can be investigated and verified, and the basis for the existing model field use and maintenance requirements can be provided.

Description

Technical Field

[0001] This application belongs to the field of brake system testing, and specifically relates to a test method for verifying the backlash of contaminants in a brake system. Background Technology

[0002] The aircraft braking control system is a crucial component of the aircraft's onboard systems. Its function is to fully utilize the frictional resistance provided by the ground to the wheels, safely, reliably, and quickly achieving braking and control during takeoff, landing, taxiing, and turning. Its performance directly impacts the aircraft's rapid response, safe return to base, and sustained combat capability, thus affecting the overall aircraft performance. To improve the system's anti-skid performance, the braking control system employs fly-by-wire control, digital anti-skid control, and hydraulic servo actuation. Because the braking control system uses hydraulic servo actuation, it is susceptible to contamination during operation due to foreign matter and hydraulic system contamination. Contamination can lead to abnormal braking response, potentially causing tire blowouts and compromising flight safety. One possible source of contaminants is the backflow from the brake system into the servo valves. Currently, major servo valve designers are researching jet pipe valves or jet deflector valves. The main advantage of these valves is their strong anti-contamination capability; however, whether their anti-contamination capability truly meets design specifications in the system remains to be evaluated. The brake servo valve is the core actuator of the system and belongs to the category of high-precision hydraulic accessories. The quality of its protection has a significant impact on the reliability of the system and the safety of aircraft takeoff and landing.

[0003] In recent years, braking systems of various aircraft have frequently experienced malfunctions such as mechanical rattling, temperature drift, residual pressure, brake lock-up, and tire drag due to foreign matter and hydraulic system contamination, seriously affecting flight safety. Therefore, it is necessary to study brake contamination backlash.

[0004] Currently, the theory of "brake servo valve sticking due to backflow of contaminants in the brake system" is still in the theoretical analysis stage and has not been effectively verified. Therefore, it is necessary to conduct experimental verification of the backflow of contaminants in the brake system. Summary of the Invention

[0005] The purpose of this application is to provide a test method for verifying the backflow of contaminants in a braking system, in order to solve the problem that the protective performance of brake servo valves is difficult to effectively test and verify in the prior art.

[0006] The technical solution of this application is: a test method for verifying the backlash of contaminants in a braking system, comprising:

[0007] Collect oil samples from the braking system of an aircraft after a certain number of consecutive flights, test and analyze the oil samples, and identify the source of contaminants in the oil samples based on the test and analysis results;

[0008] Based on the actual installation and layout of the braking system on the aircraft, a pollutant backflush verification test bench was built, and a braking system sampling point was set on the pollutant backflush verification test bench.

[0009] Based on the test and analysis results, determine the parameters of the contaminants in the oil sample. Then, according to the parameters of the contaminants, mix the dust and metal standard liquid / standard solution to the specified parameters to form test contaminants, and add the test contaminants into the brake actuator cylinder.

[0010] The braking system is controlled to perform braking operations according to actual operating conditions. After a certain number of braking operations, the oil in the system is collected through the braking system sampling point and tested and analyzed to determine whether the oil in the braking system can backflow to the braking system sampling point. If so, the number of braking operations is compared with the set number of braking operations to determine whether the design requirements are met. If not, the braking operation is performed again until the oil in the braking system backflows to the braking system sampling point.

[0011] Preferably, after the pollutant backflushing verification test bench is set up, all hydraulic accessories and pipelines on the pollutant backflushing verification test bench are cleaned.

[0012] Preferably, oil samples are taken from the braking system during the interval between two oil draining and cleaning maintenance operations, after 20 or more flights.

[0013] Preferably, when testing and analyzing oil or oil samples, a combination of detection methods is used to obtain the morphological parameters, types of pollutants, and number of solid particles in the oil or oil sample.

[0014] Preferably, the sampling points of the braking system are sampled using a line sampling method and distributed across multiple points.

[0015] Preferably, the pollutant backwash verification test bench includes a hydraulic pump source, a brake servo valve, a brake actuator, and an oil tank; the input end of the hydraulic pump source is connected to the oil tank, and a connecting pipeline is provided between the hydraulic pump source and the brake servo valve, and between the brake servo valve and the brake actuator; a number of brake system sampling points are provided on the connecting pipeline between the brake servo valve and the brake actuator, and a pressure reducing valve is provided on the outside of each brake system sampling point; a heater and a radiator are connected to the brake actuator.

[0016] The brake system contaminant backflow verification test method of this application first collects oil samples from the brake device after a certain number of consecutive flights of the aircraft to identify the source of contaminants in the oil samples. Then, a contaminant backflow verification test rig is constructed, and brake system sampling points are set on the rig. Test contaminants are then prepared according to various contaminant parameters and added to the brake actuator cylinder. Test runs are conducted, and the number of brake operations when oil backflows to the brake system sampling points is recorded. This allows for the determination of whether the brake system's anti-contamination capability meets the requirements. This method can investigate and verify the relationship between factors such as brake system pipeline length, vertical drop between accessories and the brake device, and contaminant backflow, providing a basis for the field use and maintenance requirements of existing aircraft models. Attached Figure Description

[0017] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0018] Figure 1 This is a schematic diagram of the overall process of this application;

[0019] Figure 2 This is a structural diagram of the pollutant backwash test rig for this application. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] A test method for verifying contaminant recoil in a braking system, such as Figure 1 As shown, it includes the following steps:

[0022] Step S100: Collect oil samples from the braking system after a certain number of consecutive flights. For example, within the interval between two brake system oil draining and cleaning maintenance flights, oil samples are collected from the braking system after 20 or more flights. The oil samples are then tested and analyzed to identify the source of contaminants. Specifically, a combination of detection methods is used to obtain the morphological parameters, contaminant types, and solid particle quantity parameters of the oil or oil samples.

[0023] Step S200: Based on the actual installation and layout of the braking system on the aircraft, a contaminant backflush verification test rig is constructed, and sampling points for the braking system are set on the rig. The sampling points ensure that the sampled fluid comprehensively and accurately reflects the system's fluid condition.

[0024] Preferably, such as Figure 2 As shown, the pollutant backwash verification test bench includes a hydraulic pump source, a brake servo valve, a brake actuator, and an oil tank. The input end of the hydraulic pump source is connected to the oil tank. A connecting pipeline is provided between the hydraulic pump source and the brake servo valve, and between the brake servo valve and the brake actuator. Several brake system sampling points are set on the connecting pipeline between the brake servo valve and the brake actuator. The oil collected in this way is the oil after the brake actuator returns. A pressure reducing valve is set on the outside of each brake system sampling point. A heater and a radiator are connected to the brake actuator.

[0025] During operation, the hydraulic pump draws oil from the tank, which then passes through the brake servo valve and enters the brake actuator. The brake actuator then performs the braking function. A heater and radiator maintain the normal operating environment of the brake actuator. When the brake actuator simulates operation at high altitudes, the radiator cools it down; when it simulates operation at low altitudes, the heater heats it up. After braking is completed, the oil in the sampling point of the braking system can be removed by controlling the pressure reducing valve.

[0026] Preferably, the sampling points of the braking system adopt a line sampling method and are distributed in multiple points to ensure that the sampling results represent the typical values ​​of the system.

[0027] Preferably, after setting up the pollutant backflush verification test bench, all hydraulic accessories and pipelines on the pollutant backflush verification test bench are cleaned to ensure that the overall braking system is sufficiently clean.

[0028] Step S300: Determine the parameters of various contaminants in the oil sample based on the test analysis results, and then mix the dust and metal standard liquid / standard solution to the specified parameters according to the parameters of various contaminants to form test contaminants, and add the test contaminants into the brake actuator cylinder.

[0029] This test allows the contaminant levels to directly represent the contamination amount after a certain number of flights, such as 20 flights, of the brake actuator. For example, if a traditional aircraft experiences oil backflow after 25 flights, only 5 more brake operations are needed to reach the specified operating condition. If, after installing the brake servo valve, the aircraft does not experience oil backflow after 25 flights, but only after 35 flights, it indicates that the brake servo valve has met the design requirements. In this case, the first 20 tests are no longer necessary, significantly reducing brake operation time and improving testing efficiency.

[0030] Step S400: Control the braking system to perform braking operations according to actual operating conditions. After a certain number of braking operations, collect the oil in the system through the braking system sampling point and test and analyze the oil to determine whether the oil in the braking system can backflow to the braking system sampling point. If so, compare the number of braking operations with the set number of braking operations to determine whether the design requirements are met. If not, perform braking operations again until the oil in the braking system backflows to the braking system sampling point.

[0031] By comparing the number of brake operations performed by the brake system at the sampling point where the brake fluid backflows to the system with the set number of brake operations, it is possible to accurately determine whether the anti-contamination effect after using the brake servo valve meets the requirements. If the number of brake operations during the test run is 35, and the set number of brake operations is 40, then the anti-contamination capability does not meet the requirements; if the number of brake operations during the test run is 40, and the set number of brake operations is 35, then the anti-contamination capability meets the requirements.

[0032] This application involves first collecting oil samples from the braking system of an aircraft after a certain number of consecutive flights to identify the source of contaminants in the oil samples. Then, a contaminant backflow verification test rig is constructed, and sampling points for the braking system are set up on the rig. Test contaminants are then configured according to various contaminant parameters and added to the brake actuator cylinder. During test runs, oil samples are collected from the braking system sampling points and analyzed. The number of brake operations required when oil backflows to the sampling points is obtained, thus determining whether the braking system's anti-contamination capability meets requirements. This approach allows for the investigation and verification of the relationship between factors such as braking system pipeline length, vertical drop between accessories and the braking device, and contaminant backflow. It provides a basis for the field use and maintenance requirements of existing aircraft models and supports the design, accessory and pipeline layout, servo valve selection, and contamination protection of new aircraft braking systems. Ultimately, this avoids mechanical brittle noises, temperature drift, residual pressure, brake lock-up, and tire drag caused by foreign matter in the braking system and hydraulic system contamination, ensuring flight safety.

[0033] Finally, it should be noted that the accompanying drawings of the embodiments disclosed in this invention only involve the structures involved in the embodiments disclosed in this invention. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.

[0034] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A test method for verifying contaminant recoil in a braking system, characterized in that, include: Collect oil samples from the braking system of an aircraft after a certain number of consecutive flights, test and analyze the oil samples, and identify the source of contaminants in the oil samples based on the test and analysis results; Based on the actual installation and layout of the braking system on the aircraft, a pollutant backflush verification test bench was constructed, and braking system sampling points were set on the pollutant backflush verification test bench. The pollutant backflush verification test bench includes a hydraulic pump source, a brake servo valve, a brake actuator, and an oil tank. The input end of the hydraulic pump source is connected to the oil tank. A connecting pipeline is set between the hydraulic pump source and the brake servo valve, and between the brake servo valve and the brake actuator. A pressure reducing valve is set on the outside of each braking system sampling point. A heater and a radiator are connected to the brake actuator. Several braking system sampling points are set on the connecting pipeline between the brake servo valve and the brake actuator. Based on the test and analysis results, determine the parameters of the contaminants in the oil sample. Then, according to the parameters of the contaminants, mix the dust and metal standard liquid or standard solution to the specified parameters to form test contaminants. Add the test contaminants into the brake actuator cylinder. The braking system is controlled to perform braking operations according to actual operating conditions. After a certain number of braking operations, the oil in the system is collected through the sampling point of the braking system and the oil is tested and analyzed to determine whether the contaminants in the oil carrying contaminants in the brake actuator cylinder are backflowed to the sampling point of the braking system. If so, the number of braking operations is compared with the set number of braking operations to determine whether the design requirements are met. Otherwise, apply the brakes again until the fluid in the brake system backflows to the brake system sampling point.

2. The brake system contaminant recoil verification test method as described in claim 1, characterized in that: After setting up the pollutant backwash verification test bench, all hydraulic accessories and pipelines on the pollutant backwash verification test bench were cleaned.

3. The brake system contaminant recoil verification test method as described in claim 1, characterized in that: During the interval between two oil flushing and maintenance operations of the braking system, oil samples are taken from the braking system after 20 or more flights.

4. The brake system contaminant recoil verification test method as described in claim 1, characterized in that: When testing and analyzing oil or oil samples, a combination of detection methods is used to obtain the morphological parameters, types of contaminants, and number of solid particles in the oil or oil sample.

5. The brake system contaminant recoil verification test method as described in claim 1, characterized in that: The sampling points of the braking system are arranged along the axial direction of the pipeline and multi-point sampling is performed.

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