| The pneumatic electromagnetic valve is the key pilot controlling component in shift device of commercial vehicle transmission,and its static and dynamic performance affects the controlling characteristics of whole system.In view of the failure of pneumatic electromagnetic valve of shift device in shift working condition under high pressure and high temperature,this paper establishes the designing criteria of pneumatic electromagnetic valve under multi physical field working condition,and a type of nozzle baffle direct acting pneumatic electromagnetic valve with structure of double buffering and sealing is proposed.By means of theoretical analysis,structural designing,modeling simulation,the designing parameters of components are selected and improved.The prototype is manufactured and experimental study is carried out to obtain the comprehensive performance of electromagnetic valve.The study work has certain theoretical significance and value of practical application.The main study contents are as follows:(1)Based on the analysis of working mechanism and failure mode of pneumatic electromagnetic valve,the designing criteria of pneumatic electromagnetic valve are established and working requirements,designing objectives are formulated.According to the relationship of function transformation,a type of nozzle baffle direct acting pneumatic electromagnetic valve with structure of double buffering and sealing,whose designing scheme of structure composition are proposed.(2)Combined with the designing scheme of pneumatic electromagnetic valve,the simulation model of multi physical field is constructed.The characteristics of flow field,electromagnetic field and temperature field of pneumatic electromagnetic valve are analyzed respectively.The influence of key factors on characteristics is explored.The diameter of effective valve port and valve port opening of pneumatic electromagnetic valve are defined.The electrical and structural parameters of electromagnet are selected and improved.The reasonable measures of improvement to make pneumatic electromagnetic valve meet designing objectives are put forward for the purpose of reducing temperature rise.Furthermore,the fluid structure coupling analysis of pneumatic electromagnetic valve is carried out,and results of stress and strain show that it meets the design criteria.Based on the simulation results,the designing parameters of each part of pneumatic electromagnetic valve are determined.(3)The performance test systems of pneumatic electromagnetic valve are built.The performance of electromagnetism,flow field and temperature of pneumatic electromagnetic valve is studied and verified by experiment.The results show that: The electromagnetic force of pneumatic electromagnetic valve within the stroke is more than 24.5N under the minimum driving voltage of 17 V.Under the standard driving voltage of24 V,when the material of armature is DT4 C,Steel1008 and 1J50,the opening time of pneumatic electromagnetic valve is about 5.4ms,5.2ms and 7.0ms respectively,and the closing time is about 7.2ms,7.7ms and7.7ms respectively.The coil diameter of 0.3mm and spring stiffness of3.75N/mm-4.75N/mm can meet the requirements of dynamic response.The curve of flow simulation is close to experimental curve,and the average maximum leakage is about 0.005bar/s which meets the requirements of sealing.The maximum temperature of coil at room temperature is 166.3℃ which meets the requirements of temperature resistance.The exactness of simulation model and results is verified by experiments.The structure of designed pneumatic electromagnetic valve can not only ensure the performance,but also play an effective role in buffering and the benefit of improving service life,which provides theoretical guidance for key technology of designing pneumatic electromagnetic valve of shift device. |
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