The influence of oil film inertia on piston skirt lubrication in a high speedengine is investigated by an iteration method that alternately solves the Navier-Stocks equationsand the Reynolds equa-tion by finite elemen...The influence of oil film inertia on piston skirt lubrication in a high speedengine is investigated by an iteration method that alternately solves the Navier-Stocks equationsand the Reynolds equa-tion by finite element method and difference method. The Reynolds lubricationequation including oil film inertia is developed, in which the inertia coefficient is introduced toinvestigate the effect of oil film inertia. The iteration procedure and finite formulation ofsolving the new Reynolds lubrication equation are given to analyze the effect of oil film on pistonskirt in this kind of engine. The calculation results show that the oil film inertia has someeffects on the friction force, pressure force and load capacity of oil film and its effect isobvious for the last. The Reynolds lubrication equation proposed can be also used to analyze thelubrication performance of the piston skirt in low or medium speed engine and some other lubricationproblems generally excluding oil film inertia with the inertia coefficient being set at zero.展开更多
The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of...The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.展开更多
By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new itera...By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new iteration method can trace the variations of velocity field and pressure field with time. Based on this, the mixed-lubrication model suitable for the piston skirt of high engines is proposed. By introducing the inertia coefficient, the new lubrication model includes the inertia term in oil film. The model can be also used to solve for the lubrication performances of a piston skirt in low or medium speed engines and for lubrication problem in general excluding the inertia term of oil film , when the inertia coefficient is put equal to zero. The calculation results show that the influence of oil film inertia on the friction force increases with the ratio of the piston skirt's length to its diameter, the inertia coefficient and the eccentricities of the lower and the upper piston skirt, with other conditions kept constant, while the influence of it on the load capacity of oil film is small.展开更多
In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordina...In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper （1） slip- per pressure distribution is improved; （2） hydrodynamic pressure of the combining slipper is greatly increased; （3） inclining degree is greatly reduced; （4） negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.展开更多
文摘The influence of oil film inertia on piston skirt lubrication in a high speedengine is investigated by an iteration method that alternately solves the Navier-Stocks equationsand the Reynolds equa-tion by finite element method and difference method. The Reynolds lubricationequation including oil film inertia is developed, in which the inertia coefficient is introduced toinvestigate the effect of oil film inertia. The iteration procedure and finite formulation ofsolving the new Reynolds lubrication equation are given to analyze the effect of oil film on pistonskirt in this kind of engine. The calculation results show that the oil film inertia has someeffects on the friction force, pressure force and load capacity of oil film and its effect isobvious for the last. The Reynolds lubrication equation proposed can be also used to analyze thelubrication performance of the piston skirt in low or medium speed engine and some other lubricationproblems generally excluding oil film inertia with the inertia coefficient being set at zero.
文摘The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.
基金National Natural Science Foundation of China (Grant No. 59990472)
文摘By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new iteration method can trace the variations of velocity field and pressure field with time. Based on this, the mixed-lubrication model suitable for the piston skirt of high engines is proposed. By introducing the inertia coefficient, the new lubrication model includes the inertia term in oil film. The model can be also used to solve for the lubrication performances of a piston skirt in low or medium speed engines and for lubrication problem in general excluding the inertia term of oil film , when the inertia coefficient is put equal to zero. The calculation results show that the influence of oil film inertia on the friction force increases with the ratio of the piston skirt's length to its diameter, the inertia coefficient and the eccentricities of the lower and the upper piston skirt, with other conditions kept constant, while the influence of it on the load capacity of oil film is small.
基金Supported by the National Key Laboratory Foundation Project(9140C3403010903)
文摘In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper （1） slip- per pressure distribution is improved; （2） hydrodynamic pressure of the combining slipper is greatly increased; （3） inclining degree is greatly reduced; （4） negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.
