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1、 Valve sets of position feedback based on electro-hydraulic proportional directional Dynamic Design and Simulation Throttle Of: Ligen Yi Zhang Jinxi Zhang Weixing by Joe Zhou Hua Meng Paper Keywords: dynamic simulation of MATLAB proportional directional throttle Abstract: Analysis of a feedback base
2、d on Valves two sets of displacement direction of the throttle valve electro-hydraulic proportional principle, the establishment of the linear r model of the valve, from the steady-state error and speed of the two aspects of the the dynamic characteristic simulation, the improved dynamic performance
3、 measures of the valve. Electro-hydraulic proportional control technology has evolved as a means of control, as the connection of modern microelectronics and power control of a bridge between objects. Electro-hydraulic proportional control valve is also because of its high precision, fast response c
4、haracteristics, in the high-precision mechatronic systems, engineering machinery onboard control systems, drive systems for large ship, large-scale test equipment is widely used. in which the direction of electro-hydraulic proportional throttle valve is a positive or negative according to the input
5、signal, the value, flow direction and flow control to achieve proportional control of the electro-hydraulic proportional valve. 1 Valve set the direction of the throttle valve position feedback principle of proportional The direction of electro-hydraulic proportional pilot valve throttle body mainly
6、 by the dynamic damper, the main valve and the feedback lever and so on. Which four sides of the pilot valve spool valve opening is zero, the valve sleeve designed to move the valve sleeve. Displacement feedback to facilitate the formation of the main valve opening for the negative sides of the slid
7、e valve, the principle diagram shown in Figure 1. The valve can be used both open-loop system, but also with single-piston with cylinder displacement feedback loop control system composed of position, but the signal must be used quickly step through the zero dead zone, because of its main valve with
8、 zero dead zone, can guarantee a reliable lock in place, and because of its internal mechanical displacement feedback as leverage, greatly enhanced the safety and reliability of the valve is ideal for high reliability requirements, but not too high speed requirements of the occasion. When the comman
9、d displacement signal is applied to the pilot valve, pilot valve spool movement, hydraulic pressure through the pilot valve port into the main valve cavity at both ends of sensitive hydraulic control, then control the main spool to drive the feedback lever to move, the feedback lever and then push t
10、he guide Valve sleeve valve to the pilot valve spool moving in the same direction, and then close the pilot valve port, the main valve spool stabilized at a certain location. Automatic control from the point of view, the ratio of the direction of the position of the throttle valve is a typical contr
11、ol mechanism, namely through the feedback lever to contact the main valve spool pilot valve spool displacement and relative displacement (displacement of the pilot valve spool valve cover moving the pilot valve shift differential), control the main valve and pilot valve spool in proportion to the mo
12、vement. Obviously, the valves performance depends on the pilot valve, main valves, levers, and other components of the dynamic damping characteristics. 2 Mathematical Model Mathematical model for calculating time-domain characteristics of the foundation, with reference to Figure 1, the establishment
13、 of a mathematical model of the valve. 2.1 proportional pilot valve flow equation Assuming the pilot throttle valve 4 and symmetrical windows are matched, the pilot valve inlet pressure p, constant, back to the oil pressure is 0. The pilot valve of the load flow equation q = K. (a d) a K . P (1) Whe
14、re: for the pilot valve flow gain, K for the pilot valve of the flow pressure coefficient, as the pilot valve spool displacement, the pilot valve Valve sets of feedback displacement, P is the load pressure pilot valve. 2.2 The flow equation of the dynamic damping Dynamic damping of the flow equation
15、 Where: G. For the damping fluid inlet guide, G,: for the return oil port damping fluid conductivity. 2.3 The main valve flow continuity equation Assuming the pilot valve and main valve of the connection channel symmetric and short and thick, the pressure loss in the channel and channel dynamics can
16、 be ignored, the main valve chamber in each tank to control the pressure-sensitive everywhere equal, oil temperature and the bulk modulus is constant, the inflow , out of the main valve chamber fluid flow control sensitive Where: the main hydraulic control valve chamber pressure-sensitive area: the
17、main spool displacement, the main valve chamber fluid dynamic volume control chamber sensitive volume, P p the main hydraulic control valve cavity pressure sensitive, p-based Fluid control valve chamber sensitive to oil and parietal effective bulk modulus, m the main valve spool equivalent mass, equ
18、ivalent viscous damping coefficient based valve, main valve fluid dynamic stiffness, the main valve is the equivalent load. 2.4 lever feedback equation Displacement feedback as leverage Where: F. as a lever for moving the valve sleeve driving force, m is the quality of the pilot valve sleeve valve m
19、oving, viscous damping coefficient for the pilot valve, pilot valve for the fluid dynamic stiffness. Main valve of the flow equation 2.5 the main valve to the load flow equation Where: c main valve of the orifice flow coefficient, the main valve orifice area of the gradient, p the pressure for the o
20、il, the main valve zero dead zone, p the main valve load pressure. 3 static and dynamic performance simulation 3.1 Simulation Block Diagram Based on the above model, using MATLAB / Simulink simulation software to establish the corresponding simulation model, the direction of the throttle on the prop
21、ortion of dynamic and static characteristics of simulation. The direction of the throttle ratio, the ratio of the input signal into the output of the control volume is not flow, but the power levels of the axial displacement of the spool, because the flow in addition to the axial displacement (valve
22、 opening) related, but also by the load pressure and supply pressure variations. The valve block diagram of simulation in Simulink, as shown in Figure 2. The simulation time is set to 1s, using ode45 solver, the simulation mode is set to variable step size, tolerance of 0.001. Links to free paper do
23、wnload 3.2 Performance Analysis Simulation Based on the above diagram, set the unit slope and unit step displacement of two input signals, the corresponding ring blast shown in Figure 3,4. It can be seen from Figure 3, unit ramp input main spool displacement under static following error is 0.25mm, f
24、ull stroke of 2.5% relative error, can be seen from Figure 4, unit step input, its rise time is 55 ms, the dynamic response curve without fluctuations. pilot stage fixed orifice valve sleeve displacement due to the feedback loop, in the main valve spool movement to the specified offset, the load flo
25、w, the pressure close to zero value, which corresponds to the unit step response curve shown in Figure 5. 3.3 Performance Improvement Based on the above performance curves, data, and taking into account the mechanical structure of the valve, the valve to improve the response speed of liquid to be co
26、ntrolled by changing the main valve chamber of the pressure sensitive area and the flow gain pilot valve port measures. Reduce the pressure area of the original 90%, the simulation results shown in Figure 6. Increase the flow gain pilot valve port 120% of the original, the simulation results shown i
27、n Figure 7. From Figure 6, 7 can be seen, reducing the hydraulic main valve chamber sensitive area and increase the flow gain pilot valve to help improve the dynamic response of the valve so that the rise time decreases, does not influence its stability . 4 Conclusion The mathematical model and simu
28、lation, based on fixed percentage of the valve position feedback sets the direction of displacement of the throttle command signal input at the specified under the main spool displacement, fixed displacement of the valve cover, the pilot valve load pressure, flow and other parameters change law, and
29、 proposed solution by changing the main valve control chamber pressure-sensitive area and the pilot valve port flow gain ways to improve its dynamic characteristics, is conducive to further analysis and optimization of the structure of the valve. reposted elsewhere in the paper for free download : / / eng.