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Li P.,Henan Polytechnic University | Ouyang W.-Q.,Dongfeng Commercial Vehicle Co. | Ma C.-Q.,China Institute of Technology
Zhuzao/Foundry | Year: 2014

The blowhole problem of end cover die casting is very outstanding during the trial production with a casting per mould. Blowhole formation cause is analyzed by means of InteCAST software, and then the modified project with two castings per mould was designed. Through simulation calculation on the original project and modified project, the result shows that for the original project, molten iron presents uneven filling, the outside of die castings fills obviously faster than the inside, air entrapment phenomenon exists in blowhole formation position; Whereas for the modified proj ect, liquid alloy filling mould is stable and even, overflow is designed at the last filling location and takes a good effect on eliminating gas and slag. Blowhole defect in cover castings has been effectively controlled by applying modified project during mass production.


Wang Z.,Huazhong University of Science and Technology | Wang Z.,University of California at Berkeley | Chen X.,Huazhong University of Science and Technology | Chen X.,Dongfeng Commercial Vehicle Co. | And 6 more authors.
Fuel | Year: 2016

Although exhaust gas recirculation (EGR) is widely implemented to suppress the NOx, it can increase soot emissions and decrease the thermal efficiency in internal combustion engines. Water-emulsified diesel is a promising alternative approach, as it decreases soot emissions, suppresses NOx formation, and promotes thermal efficiency through improved mixing between the fuel and air. Based on the inhibiting functions of oxygen dilution and emulsified diesel on engine emissions, a visualization study on the spray combustion of water-emulsified diesel was experimentally explored in a constant volume combustion chamber at various ambient oxygen concentrations. This study firstly examined the different combustion characteristics of water-emulsified diesel and pure diesel. Secondly, the effects of ambient oxygen concentration on combustion characteristics of water-emulsified diesel and pure diesel were investigated. Furthermore, the characteristics of soot formation and oxidation during the combustion process were revealed by flame features observed using optical techniques. Experimental results showed that a micro-explosion arose in the emulsified diesel spray which promoted mixing between the fuel and air. Local temperatures were reduced due to water's high specific heat and latent heat of vaporization, which also played important roles in ignition. The high specific heat and latent heat of vaporization had stronger effects than micro-explosions in the combustion process. The combined functions of the micro-explosion event, specific heat and latent heat of vaporization significantly decreased the soot emissions in water-emulsified diesel. Additionally, the ambient oxygen concentration affected the integrated flame luminosity and soot formation of the water-emulsified diesel. However, there were no obvious effects of the explored ambient oxygen concentrations on the ignition limit, flame boundary and flame area. The results showed that when the requirement of NOx emissions was held constant, the use of water-emulsified diesel could decrease the need for oxygen dilution by 10%. © 2016 Elsevier Ltd. All rights reserved.


Li P.,Henan Polytechnic University | Peng X.-Z.,Henan Polytechnic University | Ouyang W.-Q.,Dongfeng Commercial Vehicle Co.
Zhuzao/Foundry | Year: 2015

According to the structure characteristics of the shell die casting, die casting process design was carried out, which mainly includes selection of parting surface and pouring position as well as processing parameters, calculating pouring system section size, determining the location, quantity and size of the overflow groove by means of InteCAST software to simulate mold filling process of shell die casting. Through production verification the designed die casting process could meet the requirements of die casting production, During shell casting production, casting defects such as abnormal porosity, cold shut and misrun, shrinkage cavity were not be found. © 2015, Chinese Mechanical Engineering Society. All right reserved.


Li P.,Henan Polytechnic University | Peng X.,Henan Polytechnic University | Li F.,China Yituo Group Co. | Ouyang W.,Dongfeng Commercial Vehicle Co.
Engineering Review | Year: 2015

Shrinkage defect is a serious problem encountered during the development of automobile wheel hub made from ductile cast iron. In order to find out the reason for shrinkage formation and eliminate it in time, numerical simulation technology was performed to analyze the casting solidification process, and two modified casting projects were brought forward. Based on the simulation result, the solidification characteristics of the original project were compared with two modified projects and accordingly the optimized casting project with chill and rider feeding was selected for application during the development of the wheel hub. The result shows that casting shrinkage defect has been effectively controlled and the trial production cycle of the wheel hub was significantly shortened.


Tang K.,Dongfeng Commercial Vehicle Co. | He L.,Dongfeng Commercial Vehicle Co. | Zhao Y.,Dongfeng Commercial Vehicle Co. | Friz H.,Exa Corporation | Li B.,Exa Corporation
SAE Technical Papers | Year: 2015

The development of a new Dongfeng Heavy truck had very strict targets for fuel consumption. As the aerodynamic drag plays a crucial role for the fuel consumption, a low drag value had to be achieved. It was therefore essential to include evaluation and optimization of the aerodynamics in the development process. Because wind tunnel facilities were not available, the complete aerodynamics development was based on digital simulation. The major portion of the aerodynamic optimization was carried out during the styling phase where mirrors, sun visor, front bumper and aero devices were optimized for drag reduction. For optimizing corner vanes and mud guards, self-soiling from the wheel spray was included in the analysis. The aero results did also show that cooling air flow rates are sufficiently high to ensure proper cooling. During the detailed engineering phase an increase of the drag above the target required further optimization work to finally reach the target. Furthermore it was confirmed during this phase with thermal simulations that the design of grille openings, cooling module and fan can meet engine cooling requirements. © Copyright 2015 SAE International.


Gao L.,DongFeng Commercial Vehicle Co. | Ouyang W.,DongFeng Commercial Vehicle Co. | Min Y.,Shiyan Tianshu Induction Hardening Equipment Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

The materials and processes of engine crankshafts, and their achievable fatigue strength were summarized, and it is concluded that the forged steel crankshaft with induction hardened filleted corner can reach the highest fatigue strength. Based on this conclusion, the strengthening techniques and cost reduction ways for forged steel crankshaft were discussed. The forged steel crankshafts can be strengthened through induction hardening their filleted corners, however the precondition is to overcome the defects of quenching distortion, machining distortion and grinding burn. The approaches to reduce the cost of forged crankshaft include lightweighting by strengthening, quenching and tempering removal and free-cutting. The forged 38MnS6 steel crankshaft has a low cost and is a representative of engine crankshafts with high performance and low cost.


Li C.-S.,Dongfeng Commercial Vehicle Co. | Zhou T.-F.,Dongfeng Commercial Vehicle Co. | Yuan F.-A.,Dongfeng Commercial Vehicle Co.
Zhuzao/Foundry | Year: 2014

The analysis and optimization design of the casting technology for a medium-sized rear axle shell were carried out. The process after optimization was simulated and the process was properly adjusted according to the simulation result. The mould manufacturing and trial production were done by using of the new process, and the results show that without the effect on the castings quality, the new process not only can effectively improve the process yield and utilization rate of pattern plate, but also can improve production efficiency.


Hu L.,Wuhan University of Science and Technology | Tang Z.,Wuhan University of Science and Technology | Xu X.,Dongfeng Commercial Vehicle Co. | Yang Q.,Wuhan University of Science and Technology
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2015

The principle of steady-state energy flow method to measure the damping loss factor was derived. Through this method, a certain type of particle damper damping loss factor was carried on the experimental study. The vibration simulation of steel plate which was pasted with particle damper was compared with experimental research. The experimental results of the steady-state energy flow method show that, the particle damper damping loss factors vary with the changes of acceleration and present the obvious “piecewise representation” features. At the same time, the damping loss factors vary with the changes of the frequency and present the obvious “ridge” features. The reasons of these features were analyzed in theory. ©, 2015, China Mechanical Engineering Magazine Office. All right reserved.


Ma Z.,Huazhong University of Science and Technology | Yang J.,Texas Tech University | Jiang M.,Dongfeng Commercial Vehicle Co Ltd | Zhang Y.,Huazhong University of Science and Technology
SAE Technical Papers | Year: 2015

A new recursive method is presented for real-time estimating the inertia parameters of a vehicle using the well-known Two-Degree-of- Freedom (2DOF) bicycle car model. The parameter estimation is built on the framework of polynomial chaos theory and maximum likelihood estimation. Then the most likely value of both the mass and yaw mass moment of inertia can be obtained based on the numerical simulations of yaw velocity by Newton method. To improve the estimation accuracy, the Newton method is modified by employing the acceptance probability to escape from the local minima during the estimation process. The results of the simulation study suggest that the proposed method can provide quick convergence speed and accurate outputs together with less sensitivity to tuning the initial values of the unidentified parameters. Copyright © 2015 SAE International.


Patent
Dongfeng Commercial Vehicle Co. | Date: 2014-01-06

A connecting rod of an internal combustion engine, including a small end and a shank. The small end employs a flexible structure made of hard material. The hard material is a steel or alloy material having a tensile strength greater than or equal to 700 megapascal. The small end of the flexible structure includes a circular body, a center hole, and a flexible support. The circular body encircles the center hole, and the center hole is a complete circular hole having a constant diameter. The small end matches with a piston pin. The flexible structure of the small end operates to allow an elastic deformation of the center hole along an axial direction thereof produced by cylinder pressure exerted on the piston pin to adapt to a bending deformation of the piston pin along the axial direction.

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