Research On The Key Technologies Of High Speed Rotary Directional Control Valve

In the existing mode of excitation,electro-hydraulic excitation has been widely used due to its high power density,large output force,load adaptive ability and stepless amplitude regulation.Compared to the conventional servo valve controlled counterpart,rotary valve controlled electro-hydraulic vibration exciter can overcome the limitations of spool reciprocating motion structure and obtain higher vibration frequency.But in the applications where precision vibration is needed,there is no effective solution.Precision vibration include two aspects:accurate vibration frequency and accurate vibration waveform.Rotary valve is is the core component of the rotary valve con-trolled electro-hydraulic vibration exciter.Vibration frequency is determined by the rotational speed of the spool and vibration waveform is determined by the geometrical features of the orifice.Thus the stability of spool rotational speed and the accurate calculation of relationship between vibration waveform and orifice geometrical features are the key bottlenecks for further develop-ment of rotary valve controlled electro-hydraulic excitation technology.Supported by the National Natual Science Foundtion of China,the subject do studies on therotary valve.The calculation and compensation method of flow torques which is proposed to im-prove the stability of spool rotational speed and the design approach of orifice based on the vibra-tion waveform which is provided to improve the accuracy of vibration waveform can provide basis for the rotary valve design.The main research work of this subject are as follows.1.Baed on the structure and work principle and taken full account of research needs and machining difficulty,rectangular orifice,triangular orifice and half round orifice are designed.Flow area,area gradient and equivalent diameter of the orifices with three different shapes are calculated.The pressure-flow characteristics equation of the rotary valve is established,and the effects of structure parameters on static state characteristic are studied.The mechanical model of the rotary valve is built,the dynamic characteristics are discussed in the aspect of step response and amplitude-frequency characteristics and the effects of structure parameters and flow torques on dynamic response characteristic are studied.2.The theoretical calculate formulas of steady flow torques and transient flow torques are proposed based on the theoretical analysis of flow torques in the rotary valve.The ANSYS ICEM CFD software is used to build mesh models of internal flow field of the rotary valve,and the ANSYS/Fluent software is used to perform the CFD simulation.The change laws of flow torques with pressure drop and flow rate at the orifice and rotational speed and angular displacement of the spool are obtained.Based on the study of effects of structure parameters on the flow torques,the compensation method of flow torques is obtained.3.The mathematical model of rotary valve controlled electro-hydraulic vibration exciter is established.The effects of orifice shape,orifice axial length,orifice number,supply pressure and spool rotational speed of dynamic characteristics are analyzed.Based on the spectral analysis of vibration waveform,effects of orifice shape,orifice axial length and supply pressure of total har-monic distortion of the vibration waveform are obtained.Based on the mathematical model,the relationship between orifice flow area and vibration waveform is obtained.According to the rela-tionship between orifice axial length and vibration waveform,the design approach of orifice de-sign based on the vibration waveform is obtained.4.The experiment rig of rotary valve is established,with which the experiments of static state characteristics,flow torques and vibration waveforms are carried out.Steady flow torques coupling between unidirectional connected and bidirectional connected is obtained by experiment.The proposed methods of the calculation and compensation of flow torques and orifice design based on the vibration waveform are validated by experiment.