Design Of Differential Pressure Air Leak Detector

Airtight detection technology which is a security detection technology plays an important role in ensuring product quality. It is widely used in the following fields such as automotive、medical equipment、food packaging、gas appliances、aerospace and etc. We need to test the products to ensure that the products meet certain air-tightness performance requirements. This paper designs an airtight detector base on embedded platform, including the design of hardware and software. The research content of paper is as follows:The paper firstly describes the air tightness testing technology’s research purpose and research status of domestic and international, then introduces the principle of differential pressure leak detect, discussed formulas of leakage and leakage rates, explained the workflow and technical indicators of airtight detector, explained factors which affecting the differential pressure detection precision. In hardware design chapter, the paper describes the following contents, including the features of the selected hardware chip, the operating principle of the detecting gas path. In software design chapter, the paper describes the following contents, including the characteristics of Qt libraries, the method to build embedded Linux operating system, Qt/E graphics library and tslib touch screen calibration procedures and other operating environment, the development process of Linux drivers etc.The paper proposed the overall architecture of the system hardware, given the hardware design of the master side (upper computer) base on s3c2440a also given the hardware design of the slave side (lower computer) base on AVR Micro-controller, designed the main hardware circuit module, also designed the detecting gas path based on pressure-difference method.Designed the software function of system, gives the RS485serial port expansion driven design; then designed the master side application program based on Qt, used the multi-threading technology to achieve the function of each software module which including GUI showing、database management、network remote monitoring and RS485multi-port communication and other modules; given the overall design of the slave-side software and designed main software modules.When finished the system design work, do the systems integration testing, test the stability and reliability of the interface program, test the validity of network monitoring process, also test the range of accuracy for result and reliability to the instrument. After testing we get the test results, analyzed the data and concluded that the designs have met the requirements of the actual airtight instrument, and have put into practical application.