Design And Research On The Structure And Hydraulic System Of The Crankshaft Connecting Rod Of Inline Four Cylinder VCR Engine

With car sales rising year by year,fuel cars continued to increase,the harmful to the environment of automobile exhaust gas is more obvious.Both engine manufacturers and researchers are eager to find a new type of internal combustion engine which can not only have good power and fuel economic performance,but also have excellent discharge performance.Under this background,the engine variable technology arises at the historic moment.Through comprehensive adjustment of engine performance parameters(such as gas distribution timing,compression ratio,intake pipe length,etc.)engine variable technology make the engine in each kind of different conditions work in the best state,play to the engine's maximum potential and have excellent economy and emissions.Variable compression ratio technology has great potential.Taking performance parameters and crankshaft connecting rod size parameters of the FIC engine as reference and combining with the engine compression ratio variable structure innovation point of research team invention patent "a variable connecting rod type VCR engine connecting rod mechanism",The technical structure scheme of variable compression ratio for inline four cylinder engine was presented in this paper.The VCR structure of the inline four cylinder engine was designed and the structure size parameters were determined.Changes of the length of the connecting rod which is similar to the telescopic hydraulic cylinder lead to changes of compression ratio.Hydraulic system precisely controls changes of compression ratio.VCR crankshaft connecting rod is mainly consisted of VCR connecting rod hydraulic cylinder,VCR connecting rod hydraulic cylinder piston rod,guide sleeve,hydraulic oil conductor,VCR crankshaft.CATIA was used in the construction of the three-dimensional geometric model of the VCR crankshaft connecting rod mechanism.Analysis,calculation and calculation of the structural strength was done.The layout of hydraulic oil channel and the function of each component are analyzed in detail.Using finite element analysis software HyperWorks the static simulation of the VCR crankshaft and VCR connecting rod was analyzed.the analysis results showed that VCR crankshaft and VCR connecting rod can withstand the limit load within compression ratio range,and both under the strength limit of the material,verifying the reliability of the design proposal and feasibility of the structure.Using the software ADAMS crankshaft and connecting rod of VCR mechanism were simulated under condition of rated speed full load dynamics.Simulation results showed that in different compression ratio kinematic parameters change of the mechanism was basically the same,existing small differences due to the different length of the connecting rod;kinetic parameters of the mechanism during the power stroke was obviously different,the bigger the compression ratio,the bigger the stress between components.The requirements and principles of the hydraulic system for the compression ratio control were expounded.The hydraulic system needs high flow,high pressure,high precision,fast response and can be self locked.According to the hydraulic system control requirements,the proportional directional control valve,hydraulic pump,two-way hydraulic lock and other components were calculated and selected.