Equilibrium Design Of Internal Combustion Type Horizontally-driven Air Compressor And Simulation Study Of Multi-condition Dynamics

The internal combustion air compressor is a new device for compressor which is combined into a whole with the internal-combustion engine and the air compressor.It can convert the heat generated by the internal combustion engine into the gas pressure of the air compressor.So far the internal combustion air compressor of the double symmetric arrangement has been invented,which is denoted as Scheme 1.Due to the existence of the unbalanced torque components in the inertial force system,it will still cause the vibration of the machine.Therefore,in order to solve the problem of the dynamic unbalance,a scheme of three-way symmetrical arrangement is proposed,which is named as Scheme 2.And the two schemes are analyzed and compared,and the main research contents are as follows:The analytical method is used to calculate and analyze the two schemes respectively,and the result shows that under the premise of adding balance block,the rotating inertia force,the rotation inertia moment,and the first-order reciprocating inertia force have reached the equilibrium state in Scheme 1;compared with Scheme 1,not only the inertial force and moment above have reached the equilibrium state,but also the first-order reciprocating inertia moment has reached the equilibrium state.As a result,the internal combustion air compressor of Scheme 2 is in a state of external balance,and its overall balance performance is better than that of Scheme 1.By applying the method of balancing one by one,a balance block is arranged on each crank arm of the crank of Scheme 2 crankshaft.Through the calculation and analysis,it is confirmed that the quality of each balance block at the two ends of the crankshaft is 0.153 kg,and its eccentricity is 15.92mm;the quality of each balance block in the middle is 0.276 kg,and its eccentricity is 17.38 mm.The virtual prototype of the two schemes is simulated by ADAMS.It is confirmed that under the three working conditions(the average speed of the crankshaft is 1500 rpm,2000 rpm,2400 rmp),the maximum of the average load of the main bearing of Scheme 1 is 2228 N,and the maximum of the average load of the main bearing of Scheme 2 is 1956 N.According to the balance target of the minimum of the average load,we can see that the performance of Scheme 2 is better than that of Scheme 1.The finite element static analysis and modal analysis of the Scheme 2 crankshaft are carried out by using ANSYS Workbench.Among them,the finite element static analysis results show that the maximum equivalent stress of the crankshaft is located at the fillet of the crank pin and crank arm,and the maximum value is 305.09 MPa which is less than the allowable strength of the nodular cast iron QT700-2,proving that the strength of the crankshaft is designed to meet the design requirements;the deformation of the crankshaft is mainly distributed in the balance block,and the maximum value is 0.417 mm which belongs to the small deformation,proving that the design meets the requirement of the stiffness design.The modal analysis results show that the maximum amplitude of the crankshaft is in the crank pin,the crankshaft end face and the balance block;compared to its free mode,the natural frequency of the constraint mode of the crankshaft is larger,the lowest natural frequency is 628.42 Hz which is significantly higher than the fundamental frequency of the internal combustion air compressor in the real work(the average crankshaft speed is 2400 rpm,corresponding to the fundamental frequency is 40Hz),so that the crankshaft can effectively avoid the resonance phenomenon,proving that the dynamic performance of the crankshaft can meet the design requirements.