Modeling And Friction Characteristics Analysis Of Internal Combustion Constrained Linear Power Generation System

In order to ease the pressure of global environmental protection and energy supply,as well as the continuous growth of emissions,new energy vehicles have begun to accelerate the replacement of traditional fuel vehicles.In the process of conversion from fuel to electric drive,hybrid electric vehicle is still the focus of research and development at the present stage,among which,free piston generator(FPLG)is the hot research spot in the field of hybrid power currently.However,due to the irregular operation of the piston,the uncontrollable pressure and compression ratio of the cylinder,the poor operation stability of the system,the complex control strategy and other problems,FPLG still cannot be applied in practice and commercial production.Therefore,combining the advantages of FPLG and traditional engines,this paper proposes an internal combustion constrained linear power generation system,and carries out theoretical analysis,structural design and dynamic performance analysis.Firstly,the structure and working principle of the internal combustion constrained linear power generation system are described.The system consists of V-2 cylinder four-stroke gasoline engine and linear generator.During operation,the chemical energy is converted into mechanical energy by combustion reaction in the combustion chamber,and the reciprocating motion module is pushed to do linear reciprocating motion.The mechanical energy is shunt at the mover guide bar.Part of the mechanical energy cuts the magnetic force line to generate induced current,which is output through the linear generator,and the other part continues to be transferred to the crankshaft end for direct output.Then,the energy flow analysis of the system is analyzed theoretically,and according to the energy flow chart of the system and the energy flow of each stroke in a single stable cycle,the energy proportion and efficiency distribution of the engine and linear generator are determined.The virtual prototype of the moving mechanism of the system is simulated by ADAMS software,and the linear generator model of the system is established based on it.According to the matching engine and the design of the linear generator,within the system moving parts,assembly cylinder block,cooling system and lubricating system to carry on the design,multi-cylinder internal combustion constraint linear power system model is established.Then,a finite element model of the internal combustion constrained linear power generation system is established by using the third kind of boundary conditions,and its temperature field is verified.The results show that after cooling,the operating temperature of linear generator is kept in the range of 371.37 K ～ 383.47 K,and the temperature of linear bearing is in the range of 359.26 K ～ 371.37 K,which meets the design requirements.The friction model of the internal combustion constrained linear power generation system was established by ADAMS and Simulink,and its dynamic performance was analyzed.The results show that the friction force and friction power increase significantly with the increase of rotational speed.The peak friction force of piston is increased from208.43 N to 386.37 N,and the average friction power of the system is increased from236.78 W to 1340.14 W.The friction force and power decrease gradually with the increase of load resistance.The peak friction force of piston is decreased from 465.79 N to 345.89 N,and the peak friction power of the system is decreased from 5944.78 W to 4432.72 W.When the expected service life of bearings is extended,the friction power of bearings decreases,and the average friction power is decreased from 124.82 W to 60 W.Under the influence of the power generation device,the operating characteristics of the system cylinder pressure,piston displacement,piston speed and acceleration are slightly different from those of the traditional engine.The piston ring and piston skirt are affected by the pressure in the cylinder and the speed of the piston,and the friction force and friction power reach the peak during the power stroke.For a given engine speed,linear bearings have a constant sliding speed curve,and their friction power varies sinusoidal with piston speed.