Abstract
Variation elliptical piston skirt has better mechanical and thermodynamic properties and it is widely applied in internal combustion engine in recent years. Because of its complex form, its geometrical precision evaluation is a difficult problem. In this paper, quasi-particle swarm optimization (QPSO) is proposed to calculate the minimum zone error and ellipticity of cross-section linear profile, where initial positions and initial velocities of all particles are generated by using quasi-random Halton sequences which sample points have good distribution properties and the particles’ velocities are modified by constriction factor approach. Then, the design formula and mathematical model of the cross-section linear profile of variation elliptical piston skirt are set up and its objective function calculation approach using QPSO to solve the minimum zone cross-section linear profile error is developed which conforms to the ISO/1101 standard. Finally, the experimental results evaluated by QPSO, particle swarm optimization (PSO), improved genetic algorithm (IGA) and the least square method (LSM) confirm the effectiveness of the proposed QPSO and it improves the linear profile error evaluation accuracy and efficiency. This method can be extended to other complex curve form error evaluation such as cam curve profile.
Highlights
Piston skirt is the key parts of internal combustion engines ICEs
For QPSO the initial positions were generated by using quasrandom Halton sequence in −ε, ε, −ε, ε, −ε, ε, −ε, ε, −ε max ri, ε max ri, −ε min ri, ε min ri and the initial velocities were generated by using quasirandom Halton sequence in: −ε, ε, −ε, ε, −ε, ε, −ε, ε, −ε, ε, −ε, ε
The searching process and optimization results of the minimum zone error of crosssection linear profile by different methods are shown in Figure 5 and Table 2
Summary
Piston skirt is the key parts of internal combustion engines ICEs. Because internal combustion engines usually run under the circumstance of higher speed, larger pressure, and heavier load, it makes piston skirt work in overload conditions. Huang et al 2 proposed the algorithm based on single optimum seeking and moment method to evaluate cross-section linear profile error. Because ISO 1101 1996 recommends the form tolerance being evaluated based on the concept of minimum zone 5 , the minimum zone method MZM has received much attention in recent years, and it has been applied to solve circularity roundness , straightness, flatness, sphericity, and cylindricity error. Because the cross-section linear profile of variation elliptical piston skirt is more complex, it is difficult for traditional method to calculate the minimum zone error. Wen attempted to calculate the minimum zone solution of piston skirt cross-section linear profile error by PSO 14. In order to solve the minimum zone error of piston skirt cross-section linear profile accurately and efficiently, its mathematical model is founded, and QPSO is proposed. Mathematical Model of Piston Skirt Cross-Section Linear Profile Error Evaluation
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