The Research And Development Of New Test Method And Structure On Motorcycle Crankshaft Assembly Dynamic Balance

The core technology and component of motorcycle is the engine. When engine working, motorcycle crankshaft assembly will rotate with a high velocity. At this moment, the unbalanced inertia force generated from the crankshaft assembly will have a great influence on the motorcycle vibration and noise, the strength and life of motorcycle parts, the comfort of the vehicle occupants and so on. Therefore, to achieve the dynamic balance of motorcycle crank-connecting rod-piston assembly is important to ensure the engine working properly and reduce the motorcycle vibration and noise. Based on the study of motorcycle crank, a new method and structure are raised for dynamic balance detection system in this paper.Firstly, the crank assembly is abstracted as a slider-crank mechanism which is carried out kinematics and dynamic analysis as a physical model of the crank assembly. On the basis of this, the theory of rod-piston assembly dynamic balance is studied and the motorcycle crankshaft assembly dynamic balance which uses the dynamic balance rate y and spindle inclination (?) as the measurement parameters is discussed. Then the main parameters f=ms/mx and β describing the structure of crankshaft assembly are deduced is derived, as well as the formula of the removing weight quality parameter Am and angle λ that can be used to correct the disqualification of the crankshaft assembly.Secondly, in view of the shortage of the previous designed test system of the motorcycle crankshaft assembly dynamic balance a new structural concept is raised to ensure the measurement accuracy by removing the interference of the driven parts. The signal conditioning circuit is also introduced in this paper. The automatic zero circuit can counterbalance the inferior temperature difference of the semiconductor strain gauge sensor. The steering circuit can amplify, filter and shape the signal so that the digital signal after A/D conversion can reflect the balancing characteristics of the crankshaft assembly more accurately. On the one hand, the dynamic balance test software can counterbalance the defects of the hardware system. On the other hand, it can process the acquainted digital signals and output the detection result and data of the measured crankshaft assembly directly. Finally, through designing of motorcycle crankshaft assembly dynamic balance test system and analysis of the detection result and data, the result show that this system have achieve the design requirements. The research of this project is an available tool to solve many long-standing problems in motorcycle industry such as improving the tested products, parameter identification and correcting of the tested products and so on motorcycle industry.