Research On Measuring Accuracy And Test Bench Of Engine Torsional Vibration

Non-contact magnetic sensor is widely used in engine torsional vibration measurement for its convenient installation and simple collection system. However, the measurement results are often unstable with measurement errors. This thesis aims to offer suggestions for the measurement of torsional vibration on the basis of studying engine torsional vibration signal processing algorithms and measurement accuracy. In addition, in order to further explore torsional vibration and to achieve high-frequency and multi-band scanning, this thesis investigates several actuators in the torsional vibration test stand and a flywheel calibrator.Firstly, this thesis analyzes the engine torsional vibration signal processing and the harmonic extraction algorithm and proposes a two-lane instantaneous calculation method, which not only can effectively filter missing pixels, but also function under the condition of a variety of speed and sampling frequency. Secondly, with the combination of standard signals and theoretical analysis, this thesis studies the impact of average speed, cycle sampling density, speed changes and high-frequency counting method on torsional vibration measurement.As to the issue of the high-frequency and multi-band scanning of the torsional vibration test bench, this thesis develops eccentric axis actuators, designs and analyzes the crank rod actuator, the spring crank rod actuator and cross crank shaft universal actuator. Moreover, the method of achieving multiple harmonic of the same speed has been discussed in the subsequent section.In order to simulate torsional vibration test, this thesis constructs a torsional vibration test bench of 1.4L four-cylinder gasoline engine. After a thorough analysis and measurement of the torsional vibration, the present research verifies the signal processing algorithms and gives feasible suggestions to the coupling parameter design and improvement. Meanwhile, this thesis designs a flywheel device calibrator and analyzes its dynamics characteristics.