Crankshaft Shaft Torsional Oscillation Digital Test System

Endlessly emerging of new technology gradually fulfilled low energy-waste and exhaust target in internal-combustion engine research and manufacture industry, at the same time, the strict request was brought forward at structure reliability design, vibration and noise reduction of internal-combustion engine, one of all the problems, the cranftshaft torsional vibration problem was very outstanding, and now NVH(Noise,Vibration and Harshness)has been paid attention to in distribution market. Pursuing perfect torsional vibration theoretics and seeking methods to solve torsional vibration is emergent. Higher precision and higher reliability test equipment is effective tool to achieve this target. On the base of these reasons, considering technology of sensor, SCM (Single Chip Micyoco) and DSP(Digital Signal Processing), adequately utilizing capability of microcomputer, adopting the technology to measure time through high frequency counter, a higher precision digital test system for internal-combustion engine torsional vibration has been studied and developed in this paper.The system is comprised of hardware and software. Hardware is comprised of signal gear, sensor and data acquisition card. Some functions are carried out by hardware, such as, creation, acquisition, filter, regulation, transmission of signal and the count of rectangle-wave. The principle of developing hardware is to reduce interfering signal. Some work completed as follows: selection of high frequency crystal oscillator, high speed processor MCU and big buffer flip-latch, USB interface, the flip-latch of the count of several gear-tooth pulse is independent of MCU time-sequence by reasonable working-flow design.Following functions are completed by software: reading time-sequence from buffer of data acquisition card, variously transforming of time-sequence, disposing abnormal point and filtering of digital signal, counting of torsional vibration amplitude, protracting torsional vibration wave under the steady rotating-speed, spectrum analysis, protracting torsional vibration amplitude-rotating speed curve and printing test report, etc. The principle of developing software: scientificity and veracity of transform disposal, high efficiency of running speed, high conveniency of software usage, software function is expandable and software maintenance is convenient, etc. Some work has been completed, such as, software module has been designed in VC++6.0 environment, the arithmetic of abnormal point disposal has been studied based on hardware characteristic, some influences of torsional vibration measuring accuracy have been restrained, trosional vibration amplitude has been revised in spectrum analysis and distilling harmonic amplitude, the communication between this software and Microsoft word2003 has been realized, 'chm' help document has been made, etc.In the course of developing the test system, signal induction, signal transmission, data acquisition and data analysis disposal of this system have been verified on a simplified test bench. After system integration, tests haves been made on diesel engine experimental bench, results testified system anticipative desire had been achieved basically.