0 Preface
The aero engine is the core component of the aircraft and is the power source for the aircraft. The quality of aero-engine maintenance directly affects aircraft usage and even affects flight safety. During the life of the aero-engine, in order to ensure flight safety, it is necessary to periodically test the aircraft engine to check the performance of the engine. There is an indicator instrument in the cockpit showing the test parameters, but the observation is inconvenient, the precision is not high, the human error is large, and the crew members report that when the engine is tested, a large number of parameters need to be recorded, especially when the engine fails to test the vehicle. The analysis of the test data makes the test run long, and the data recording and analysis are inconvenient. These shortcomings are very unsuitable for modern high-tech war requirements and cannot meet the maintenance requirements of the field. Based on PC104 bus technology, this test vehicle parameter detection system can detect, display, store and print the main technical parameters in the engine test process in real time, so that the crew can accurately analyze, judge and eliminate engine faults and improve engine reliability. At the same time, the maintenance time can be greatly shortened, manpower and material resources are saved, and the maintenance of the engine is more scientific and more targeted.
1 Design foothold
1.1 Guaranteed reliability
System development has always focused on its reliability and safety. For purchased equipment, the supplier must submit the products to meet the reliability requirements of the GJB standard. The supplier provides complete product qualification certificates, maintenance instructions and other documents, and signs the contract to ensure the reliability of the purchased equipment. . The hardware and software design is strictly in accordance with the design specification and reliability outline. The electromagnetic isolation sensor is used. The signal input and output of the sensor are isolated from the power supply. No circuit is added to the instrument on the aircraft. The original instrument can work normally. . When the system is connected to the aircraft, even if the tester does not work or does not work properly, the original instrument on the aircraft can work normally.
1.2 Guaranteed operability
The system development adopts the people-oriented design idea, fully considers the use requirements of the crew, has a high degree of intelligence, good man-machine interface, simple operation, convenient use, and good operability.
1.3 Guaranteed interchangeability
The system design fully considers the interchangeability of components, try to use standard and versatile components, and select aviation products for military products to ensure that the equipment has good interchangeability and is convenient for maintenance by maintenance personnel.
1.4 Guaranteed accuracy
Guaranteed accuracy is the design idea that has always been adhered to during the development of the system. The following methods are mainly adopted in the development: First, the high-precision sensor is selected to make the accuracy of the collected signal meet the test requirements: Second, the software filtering method is used to filter out the interference data. To ensure the accuracy of the collected data; the third is to ensure the accuracy of the hardware design, the data will not affect the normal operation of the on-board sensors and instruments, and ensure that the collected data is true and accurate.
2 Features and functions
The aero-engine test parameter detection system is a device developed on the basis of foreign ground detection equipment. It adopts PC104 bus industrial computer and EL screen display, which makes the detection system have the characteristics of small size, light weight, easy to move, simple operation, high automation, good reliability, rich display information and good man-machine interface. It can fully detect the cockpit. The engine performance parameters are displayed with higher accuracy than the cockpit indicator.
System functions include: 1) real-time detection and display of high and low pressure rotor speed of engine, engine vibration speed, oil pressure, oil temperature, main and auxiliary oil pressure and exhaust temperature: 2) plot test curve in real time; 3) Save the test parameter data; 4) After the test run, you can view the data of each parameter during the test run and the test curve; 5) The tester communicates with the computer data, and the data of each parameter in the test run is transmitted to the computer, and the crew can be at the computer. View data for each parameter to analyze and troubleshoot.
3 structure and working principle
The design idea of ​​the test parameter detection system is realized by using the original sensor of the aircraft without affecting the normal operation of the aircraft instrument and ensuring the safety and reliability of the engine work. The operation of the inspection system does not affect the normal operation of the maintenance personnel. When using the vehicle, the engine program is tested according to the ground. The system includes sensors, controllers, data acquisition cards, detection circuits, keyboards, power supplies, and displays. The detection principle is shown in Figure 1.
During the test run, the engine output high and low pressure rotor speed analog signal, vibration speed analog signal, oil pressure analog signal, oil temperature analog signal and exhaust temperature analog signal are taken from the connecting plug of the aircraft, and the parameters are taken through the detecting circuit. The analog signal is isolated and converted to a DC voltage signal. The main and auxiliary oil passage fuel pressure transmitters are connected to the measuring joints on the fuel main and auxiliary oil feed rings. The pressure transmitter senses the oil pressure change and outputs a DC voltage signal proportional to the fuel pressure of the main and auxiliary oil passages. These DC voltage signals are converted into digital quantities by the data acquisition card and sent to the controller, and the values ​​of the parameters are calculated by the program in the controller. The controller stores the detected data in the data memory through program control, and displays the test data and the test curve of each parameter on the EL display.
The controller is the core part. The main function is to read the data corresponding to each parameter from the data acquisition card according to the user program, and calculate the actual value of each parameter and store it in the data memory; control the EL flat panel display to display the man-machine Interactive interface, test data for each parameter, test curve, etc. It uses the embedded industrial computer PC40 bus produced by Shengbo Technology Co., Ltd., model SysCentreModule/SDXpn. The main technical data are: 1) embedded 486 processor, working frequency 50MHz; 2) 16M bytes of RAM; 3) 1M memory; 4) standard DMA, interrupt timing controller; 5) industrial standard BIOS with extension; 6) VGA supports monochrome LCD, EL display, and analog CkT; 7) supports DOC electronic disk; 8) power supply requirements: +5V ± 5%, 0.8A; 10) working environment temperature: -40 ~ +80 ° C .
The data acquisition card completes the acquisition of analog signals of various parameters, and adopts the multi-function data acquisition card PM511P of PC104 bus produced by Beijing Zhongtai Research and Development Technology Co., Ltd., with 16 A/D conversion channels and 4 D/A channels. 24 channels of programmable digital input and output, 3 counting channels, and can work under -40 ~ +80 °C environment conditions. In addition, the acquisition card also completes the collection of keyboard signals.
The power supply is used to convert the 27V DC power of the airport into +5V, ±12V, +24V DC required by the internal circuit of the system. Two DC-DC converters are used to convert 27V DC to PC104 and other electrical components. +12V, -12V, +24V and +5V DC power supplies. It has high conversion accuracy and can work stably in the environment of -40 to 55 °C.
The EL display is used to display the prompt characters and the detected parameters of the parameters and the test curve of the human-computer interaction. The model used is EL640.480-AGI-ET. Its main technical parameters are: 1) Resolution: 640 & TImes; 480; 2) Size: 8.1 inches; 3) Power supply: 12V; 4) Operating temperature: -40 to +85 °C.
The DOC electronic disk is used to store various parameter data detected during the test run, and is also used to store the operating system file of the controller, the control program file of the instrument, and the like. The DOC electronic disk has a capacity of 128M. The keyboard uses a simple switch keyboard, and the keyboard signal is sent to the industrial computer of the PC104 bus through the data acquisition card.
The keyboard on the panel is used for human-computer interaction to input commands and data to the controller. It has 6 keys and uses a simple switch-type keyboard. The keyboard signal enters the controller through the data acquisition card. The interface is simple and convenient.
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