Research On Assembly Dynamic Balancing In The Crankshaft Connecting Rod Of The Motorcycle Engine

The unbalance in the crankshaft and connecting rod mechanism is the main causeof the motor’s vibration, and it has a significant impact on the performance and comfortof the motorcycle, so that the unbalance need to be measured and adjusted. However,the current measurement for the unbalance in the crank-link mechanism most adopt themethod of measurement for the single crankshaft or using the equivalent ring, whichresult in that the unbalanced inertia force is still unsatisfactory after assembly of crank-connecting rod–piston, and the problem have not get a better solution for a long time.In the assembly unbalance measurement system used in some enterprises, the indexingmechanism is used with which the multiple measurement is needed in one rotationperiod, so that the measuring efficiency is too low to meet the productiondemand.Therefore, it is necessary to produce a new assembly measurement system to improvethe accuracy and efficiency of the unbalance measurement.In the present study about the inertial force of the crankshaft-connecting rodmechanism in the single cylinder engine, the second order inertia and above is usuallyignored. However, it suggests that the errors of the largest inertia force and unbalanceratio could be up to30%, which may leads to large deviation for the adjustment ofdynamic balance in certain conditions. A new theoretical inertial graph similarly in8-patern was get based on the synthesis inertia force of first and second order. Itsproperties was researched and new description parameters were put forward for the newgraph-the second order inertia force and secondary dip angle. Considering the secondorder inertia, the relation between maximal inertial force, imbalance efficiency andparameters of mechanism were restudied. And also the method for the election andadjustment of structure parameters was presented.An orthogonal measuring mechanism is put forward on the basis of the rotorvibration theory with five degrees of freedom. In this mechanism, one vibration sensoris aligned with the axis of the simulative cylinder and is orthogonal to the other one, bywhich thecorresponding vibration components of the unbalanced inertia force in twodirections are obtained, and then the unbalanced inertia force at any time could becalculated by vector synthesis. Based on this vibration measuring mechanism, thesystem could rapidly measure out all the value and the distribution of the unbalancedinertia force by running the machine for once. The mechanical vibration structure of the measurement system introduced, the theory and operation of the calibration and theimbalance compensation of the system are studied.In the dynamic balance measuring system, the MCU PIC16F877A is used as themicroprocessor for the acquisition and processing of the vibration signal and thereference signal, and is controlled by the IPC through the serial port. The key hardwarecircuit in the measurement system, the electrical signal processing and control theoryare discussed. The software interface for each module are introduced, the measurementdata processing method is given, and the optimization algorithm PSO used to design theassisted design module for the balance is produced.