| High-speed on/off valve as digital electro-hydraulic control components is developed in the 1980s, it is small、fast switching speed、flexible control、high reliability, and can be directly controlled by the computer without D/A conversion interface, and is widely used in aerospace field、engineering machinery、automobile、metallurgical machinery、mining machinery, agricultural machinery and other equipment. In recent years, high-speed on/off valve is developed in both high power and micro-flow development trends, but both demand rapid response of high-speed on/off valve. Miniature high-speed on/off valve has fast response because of its small spool mass and low flow rate, but large-flow is extremely difficult in improving response speed, because of its large-flow、spool’s high quality, large-travel, high work pressure and other factors. High-speed on/off valve’s response speed improving can make control system not only to improve the speed and control accuracy, but also to ensure reliable operation of the system in case of emergency. In recent years, with the hydraulic system towards high pressure, high-power and high-speed direction, flow and response speed switching valve is put forward higher requirements.To simultaneously improve the flow and speed of response speed switching valve, studied can be started from the three following aspects:spool’s innovative design and optimization of the body structure; electromechanical transducer’s structural innovation and control method research; This topic needle ejection system and high-power quick-locking hydraulic system for high-speed on/off valve flow, fast response and working pressure requirements, key technology research of high-speed on/off valve are as follows:(1) The hydraulic servo spiral can be used to design the large-flow high-speed on/off valve to improve its flow-rate and dynamic characteristics because it’s fast response, high natural frequency, good dynamic performance, simple structure,etc. To overcome such shortcomings as:the traditional single-stage direct-acting electro-hydraulic valve is difficult to achieve high pressure and large-flow, and pilot-controlled electro-hydraulic valve’s structure is complex, on the basis, the scheme is purposed that hydraulic servo spiral is be used to design the spool, and arise spool large stroke and spool driving force, to improve the high-speed on/off valve’s flow and response speed. The dynamic characteristics of the hydraulic servo spiral is researched, the influence of main structure parameters to valve frequency characteristics and step response such as radius of high and low pressure hole, initial chord height, system pressure and length of sensitive chamber are all studied. Theoretical analysis shows frequency response at-3dB amplitude attenuation is about 160Hz, the step response time is about 2ms, the research results development of high-frequency, high flow switching valve foundation.(2) Anew type of rotary solenoid with a six-blade rotor is proposed for the 2D hydraulic valve, which has a low rotation inertia, large angular displacement, fast response characteristics, particularly suitable for 2D hydraulic valves’electromechanical transducer. Base on the study of its working principle, mathematical model is established about the rotating magnet, the influence of structural parameters on its static and dynamic characteristics is simulated and analyzed, on the base prototype production and experimental platform building, the rotary solenoids’static and dynamic characteristics and experimental are studied, the rotary solenoid has constant output driving torque 0.04N.m,12.5° angular displacement, and about 5ms dynamic response time.(3) According to the requirements of hydraulic ejection system,2D electro-hydraulic high-speed on-off valve is proposed, adopts sleeve-free structure and the outer surface adopts hollow structure to reduces mass and volume; Base on the digital simulation and experiment results of dynamic characteristics are quite coincide and show commonly:the working pressure of 28MPa, when the spool stroke 0.8mm, step response time of about 5ms, the flow-rate of valves is up to 60L/min with 6mm path diameter; The electro-hydraulic high-speed on/off valve can work stably in the temperature range in-55～+135℃. And it can switch 200,000 times at the working pressure of 42MPa, to meet the performance requirements of 4th generations fighter (J20).(4) The design of 2D electro-hydraulic valve control large flow poppet valve is proposed, according to that high-power hydraulic quick-locking system demands high-speed on/off valve’s flow-rates is 450L/min and dynamic closing time is less than 8ms. In order to solve the problems of the spool’s shock and vibration of the large-flow high-speed on/off valve, a solution of the spool’s squeeze oil-film damper is put forward, theoretical analysis shows that the squeeze oil film’s initial thickness is the most influencing factor of its damping effect, based on the structure design of the squeeze oil-film dampers, the theoretical models of its damp and output force are established, and the influence of structural parameters on damping performance is analyzed. Both theoretical and simulation results show:the damping buffers and the damping force of squeeze oil-film is inversely proportional to the cube of the oil-film thickness. and the spool velocity don’t decline in the first 97.5% spool stroke because that the damper is no effect on the speed of the spool, in the last 2.5% spool stroke, the spool is damped by the force of the squeeze oil film damper, and the final velocity of the spool decline quickly, the squeeze oil film damper does not extend the spool closing time.(5) In order to improve the locking speed of the large-flow cone valve, the dynamic characteristics of the mathematical model is establishment, some key structure parameters impact on the cone valve is studied and be optimized, simulation results show that:spool dynamic closing time of about 8ms in a 6mm stroke, the smaller initial thickness of the squeeze oil-film, the better spool cushion, when the initial squeeze film thickness is about 0.1mm, the maximum force of squeeze oil-film can reach 43KN, the average resistance force can up to 3T in the final stroke of 0.15mm, the spool speed is rapidly reduced from 3.4m/s to 0.1 m/s, the large flow rate high-speed on-off valve’s spool vibration and shock is disappear.(6) The experimental programs of static and dynamic characteristics of the large flow rate high-speed on-off valve are designed, the valve prototype is developed and the test system of the dynamic and static characteristics are built. The valve’s leakage is 8.249mL/h when the switch times is 100 without the spool’s squeeze oil-film damper;but the valve’s leakage is 3.85mL/h when the switch times is 5000 with the 0.1mm squeeze oil film damper, dynamic off time is about 8ms, it meets the design requirements of the large flow rate high-speed on-off valve. the large flow rate high-speed on-off valve can meet the performance requirements of high-power hydraulic quick-locking system relative to the no squeeze film damper one. |
