The Internal Combustion Engine Data Acquisition And Analysis System, The Windows Nt Platform

In this paper, the author discussed the combustion data acquisition of internal-combustion engine in unsteady operation conditions under Windows NT system. It is a momentous attempt and improvement of data acquisition system compared to those formerly based on DOS, Windows 3.x and Windows 9.X. Taking the mighty function and the high degree of stability and reliability of Window NT into consideration, it is meaningful to explore the data acquisition system under such condition. In this paper, the data acquisition with high speed and great capacity was realized and a unique way of acquisition, memory and transmission was put forward: to form the loop buffer storage area to acquire and store data by two pieces of ordinary RAM and with the aid of DMA to transmit data, the data in the buffer storage area was sent into the main memory. Thus, the data acquisition was realized under Windows NT with high efficiency and speed; the problems of the rigid restriction such as the Windows NT could not directly visit the device port and interruptive vector were settled by the DLL mechanism of Windows. With the full application of multithreading technology and the advantage of NT in supporting the symmetrical multi-processor (SMP characteristics), the operating efficiency was greatly improved. As far as the experimental data is concerned and because of the characteristics of internal-combustion engine experiment, the clearance between moving components, linking passage of pressure transducer and crankshaft torsion angle will cause the dynamic top dot to deviate from the static top dot during the dynamic process. Moreover, because of the unavoidable existence of combustion pressure oscillations and pressure oscillations of gases in linking passage of transducers, there are a lot of errors in the original data. These factors are against the accurate evaluation of the working condition and performance of internal-combustion engines. In order to eliminate the influence caused by these errors, first, the author introduced the "five-time &four-dot simulation synthesize method" to amend the top dot position; and then the "seven-dot movement average method" was utilized to smooth the indicator diagrams with saw-tooth sharp waves. Thus a satisfactory effect was achieved.