可变压缩比活塞的力学仿真研究

发布时间：2018-04-03 07:55

本文选题：可变压缩比　切入点：VCR技术　出处：《武汉理工大学》2011年硕士论文

【摘要】：VCR (Variable Compression Ratio,可变压缩比)技术能够有效改善发动机的低负荷性能。本文针对一种VCR活塞技术方案,利用动力学仿真软件ADAMS及有限元分析软件ANSYS联合建立了VCR活塞的三维动力学仿真模型,确定了VCR活塞模型的边界条件。VCR活塞静态模拟试验和VCR活塞动态响应模拟试验对比验证了VCR活塞的动力学仿真模型,完成了多方案的VCR活塞的动力学仿真计算分析,仿真计算结果验证了所研究的VCR技术方案的可行性。在VCR活塞的动力学仿真过程中,基于ADAMS模拟了机构各部件之间刚体受力位移,利用有限元软件ANSYS建立了碟形弹簧的3D柔性体模型,模拟碟形弹簧与钢球的接触,并考虑了接触点变化对刚度的影响。VCR活塞仿真模型采用ADAMS耦合ANSYS求解,能够更为真实的反映VCR活塞机构的实际工作状况。提出了一种新的建模方法,能够在ADAMS和ANSYS耦合求解中处理轴对称问题。根据VCR活塞机构中各零部件的实际装配关系和空间位置,在ADAMS中定义了整体结构的约束和各零部件之间接触关系。接触参数根据材料性质、接触状态设置,为了验证VCR活塞仿真模型的正确性,根据静态模拟试验和动态模拟试验的试验条件建立了对应的力学边界条件,为了仿真VCR机构在发动机中的工作状况,建立了发动机的力学边界条件。静态模拟试验采用液压式万能试验机对各种结构方案的实际VCR机构和弹性元件施加静力载荷,动态模拟试验利用MTS试验机对实际VCR机构施加动态模拟载荷。试验数据与仿真结果的比较验证了模型可行性。采用所建立的VCR活塞的动力学仿真模型对135型非增压柴油机进行了多方案VCR活塞动力学仿真计算分析,作用在活塞顶的缸内气体力由发动机性能仿真提供,分析了转速、负荷、运动件质量和结构参数对VCR机构力学性能和动态响应的影响。仿真计算表明,所提出设计的VCR技术方案具有较好的动态响应,能够实现预期的设计要求。
[Abstract]:VCR variable Compression Ratio (variable compression ratio) technology can effectively improve the low load performance of engine.In this paper, the three-dimensional dynamic simulation model of VCR piston is established by using ADAMS and ANSYS, a kind of VCR piston technology scheme, which is based on the dynamic simulation software ADAMS and the finite element analysis software ANSYS.The boundary conditions of the VCR piston model are determined. The dynamic simulation model of the VCR piston is verified by comparing the static simulation test of the VCR piston model with the dynamic response simulation test of the VCR piston model, and the dynamic simulation analysis of the VCR piston with multiple schemes is completed.The simulation results verify the feasibility of the proposed VCR technology.In the process of dynamic simulation of VCR piston, the displacement of rigid body is simulated based on ADAMS. The 3D flexible body model of disc spring is established by using finite element software ANSYS, and the contact between disc spring and steel ball is simulated.Considering the influence of contact point change on stiffness, the simulation model of VCR piston is solved by ADAMS coupling ANSYS, which can reflect the actual working condition of VCR piston mechanism more realistically.A new modeling method is proposed, which can deal with the axisymmetric problem in the ADAMS and ANSYS coupling solution.According to the actual assembly relation and space position of the parts in the VCR piston mechanism, the constraint of the whole structure and the contact relation between the parts are defined in ADAMS.In order to verify the correctness of VCR piston simulation model, according to the test conditions of static simulation test and dynamic simulation test, the corresponding mechanical boundary conditions are established.In order to simulate the working condition of VCR mechanism in engine, the mechanical boundary condition of engine is established.The static simulation test uses the hydraulic universal testing machine to exert static load on the actual VCR mechanism and elastic elements of various structural schemes, and the dynamic simulation test uses the MTS testing machine to exert the dynamic simulation load on the actual VCR mechanism.The comparison between experimental data and simulation results verifies the feasibility of the model.The dynamic simulation model of the VCR piston is used to simulate and analyze the dynamics of the 135 type non-turbocharged diesel engine with VCR piston. The gas force acting on the top of the piston is provided by the engine performance simulation. The speed and load of the engine are analyzed.Effects of mass and structure parameters of moving parts on mechanical properties and dynamic response of VCR mechanism.The simulation results show that the proposed VCR technical scheme has good dynamic response and can meet the expected design requirements.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TK403;TH113

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