To study the fuel saving algorithm for assisted driving of high-speed tractors,taking a cer-tain tractor as the research object,based on the analysis of driving behavior of excellent drivers,a predic-tive cruise control strategy for the tractor in actual road spectra was designed.In addition,the vehicle simulation software Cruise and strategy modeling software Simulink were used for joint simulation.Results show that compared with cruise control,the fuel consumption is reduced by 11.57%per 100 kilometers under the predictive cruise control strategy,and the fuel saving rate during actual vehicle testing is 6.8%.
The three-dimensional simulation model of large deformation of fluororubber seal ring was established by finite element method to study the lube oil pump rectangular seal in the bolt assembly process and different temperature contact pressure,filling rate and compression rate on the impact of seal-ing performance.The results show that the large deformation analysis of the seal can get accurate contact pressure in the sealing area.And under the low temperature condition of-40℃,the lubricant pump cold shrinkage to the middle increases the extrusion of the contact area to make the contact pressure increase.As the temperature rises to 120℃,the lubricant pump thermal expansion reduces the contact pressure,the maximum contact pressure under each working condition is greater than the oil internal pressure of 1.98 MPa.As the temperature increases,the filling rate of the seal gradually increases,and the filling rate of the seal at different temperatures is less than 85%,while the compression rate of the seal de-creases,and the compression rate at different temperatures is in the range of 13%to 36%.The filling rate and compression rate meet the design requirements.
An efficient oil gas separation structure integrated on the cylinder head cover for a Na-tional VI diesel engine was designed.The adsorption cotton was equipped in the fine separation unit and worked well for small oil fractional particles.The basic structural parameters of the product were deter-mined through computational fluid dynamics(CFD)gas-liquid two-phase flow analysis method,and the separation efficiency of oil droplets with different particle sizes and gas flow pressure loss were tested us-ing the German Topas oil-gas separation equipment.By adjusting the diameter of orifice plate in front of the filter cotton,the effect of different airflow impact velocities on the adsorption effect of the filter cotton was studied,and the optimal diameter of the accelerating pore was determined.The results show that af-ter adding adsorption type filter cotton,the separation efficiency of small oil droplets within 0.5μm can be improved by about 25 percentage points.The final designed sample can be verified to be qualified through engine bench testing,and the oil mass flow rate at the outlet is about 0.48 g/h.
For natural gas engines,exhaust gas recirculation(EGR)can effectively suppress the generation of nitrogen oxides(NOx)while reducing the combustion temperature in the engine cylinder.However,differences in EGR rates among cylinders can lead to differences in combustion,thereby in-creasing the risk of misfire and detonation.EGR rate tests on each cylinder and computational fluid dy-namics(CFD)simulation analysis of the intake pipeline were conducted based on a China Ⅵ natural gas engine.By optimizing the structural design of the intake pipeline,the uniformity of the EGR rate was ef-fectively improved.The uniformity of EGR rate in each cylinder was≤2.5%,which meets the design re-quirements and can provide reference for the design and development of intake pipes in engines.
Taking the 6.7 L China Ⅵ diesel oil gas separator as the research object,the structural characteristics of the oil gas separator were analyzed.Based on the original oil gas separator structure,the oil gas separator was optimized and designed.Computational fluid dynamics(CFD)finite element analysis software was used for steady-state pressure and flow rate analysis,and experimental verification was conducted on the Topas oil and gas separation test bench in Germany.The results show that by opti-mizing measures such as adding filter cotton,reducing pore size,and increasing the pore number to the oil gas separator,the design goal of less than 1.0 g/h of the oil carrying mass flow rate for the crankcase ventilation system has been achieved,and its emissions have met the requirements of the national emis-sion regulations.
