Application of Cartridge Valve in Hydraulic System of Electro - Hydraulic Control Support

The application basis and prospect of the cartridge valve in hydraulic system of electro-hydraulic control support are discussed. The design scheme is proposed and the working principle is analyzed. That the cartridge valve flow capacity, fast response, the use of electro-hydraulic pilot control, especially suitable for the type of stent conditions, in line with technological trends, it is worth promoting. Keywords: Cartridge valve; Electro-hydraulic control; Bracket; Hydraulic system 1. Application basis Analysis of low moving speed has become an important factor restricting the yield of fully mechanized mining. In order to speed up the moving speed, cartridge valve is adopted in hydraulic system of bracket. Cartridge directional valve is also used as a pilot valve solenoid valve, the main valve (cone valve) for pilot control, the control principle is equivalent to the electro-hydraulic control valve, but the cartridge valve flow capacity (up to 10000L / min above) large , Quick response, reliable work and other outstanding advantages, is the unrivaled tubular valve, making it more suitable for use in the stent electro-hydraulic control system, without the need to develop a special high-flow solenoid valve pilot valve, both Meet the requirements, but also improve performance, improve the degree of generalization, from the fundamental solution to the problems caused by the inherent defects of the tube valve. In addition, the use of cartridge valve design bracket hydraulic system also has the following advantages: (1) the advantages of cartridge valve is very suitable for the stent conditions. The working conditions of the hydraulic support are as follows: medium viscosity is low, working pressure is high, the flow is large, the working environment is harsh, and the medium is polluted seriously. The advantages of cartridge valves can be fully utilized. (2) In line with the development trend of fluid transmission technology. To reduce the use of cost, eliminate environmental pollution, fluid transmission technology is toward the use of pure water medium direction. Hydraulic supports are high-water-based emulsions that are relatively close in nature to pure water and are likely to be the beneficiaries of the development of this technology. They are tending to adopt pure water working media. Due to the low viscosity of water, the valve is required to have good sealing to improve the system's efficiency. Cartridge valve cone sealing, with excellent sealing performance, more suitable for use in pure water medium, should be used as the preferred valve of pure water bracket. (3) strong anti-pollution, reliable work. Stents working in the coal mining surface, a high degree of media pollution, the valve core wear and tear, shortening the valve life, which also led to a variety of failures of the bracket, reducing work reliability, increased maintenance time and reduced work Productivity. Cartridge valve sleeve and valve sleeve without strict requirements, wear light, easy to plug, it will not produce hydraulic clamping phenomenon, the media can still be dirty when the stent hydraulic system to ensure normal and reliable work. (4) to meet the needs of some special conditions. Such as the cycle to pressure the strong hard and difficult to take off the roof of the support bracket, sudden pressure in the roof, the lower column control valve in the safety valve, through a large instantaneous flow, the normal safety valve through Flow capacity can not meet the flow requirements far, so specially designed inflatable large flow safety valve to adapt to this condition. However, the valve of the complex structure, manufacturing difficulty, high assembly requirements, poor reliability, it is difficult to meet the requirements. Moreover, the lower column also install a common safety valve to adapt to the needs of normal working conditions, which will undoubtedly increase the number of components and manufacturing costs. The use of cartridge relief valve, you can easily solve this problem, but also make the system simplified. 2, the working principle analysis Based on the above analysis, put forward the use of cartridge valve design electro-hydraulic control hydraulic system design ideas and programs, the working principle shown in Figure 1. The system consists of electrical and hydraulic two parts, the internal storage rack motion program microcomputer (central and stent controller) issued a directive, the cartridge pilot valve in the first pilot solenoid valve, opening and closing the corresponding two-way cone valve , Connect or disconnect the column or push the jack of the oil, so that in accordance with a certain order of action. Column or push jack working conditions by the pressure and displacement sensor feedback to the controller, the controller based on the feedback signal to determine the next action. Since the central controller and rack controllers are networked with one another, control of either rack from the central controller or from each rack can be made. The role of the central controller is to control and coordinate the controller of each stand. In addition, it can automatically program and modify system parameters, monitor the working status of each stand, and display the running speed of shearer. It provides individual control, sequential control, group control and fully automatic control of the various movements of the brackets. The stand controller directly controls the stand by the plug-in directional control valve, and sends the working condition data collected by the sensor to the other stand and the central controller. After receiving the signal, the support hydraulic system will accomplish the following actions: (1) The action of the lifting column is controlled by the cartridge directional control valve 8. When the pilot valve solenoid 1YA of the directional valve 8 is energized and the 2YA is powered off, The valve is switched to the left position, b and d on the four 2-way valve on the chamber through the pressure oil, is off, a and c on the chamber through the tank, is open, the pressure pump provided by the 2-pass Valve c and the pilot check valve (at this time the pilot check valve in the position of the two three-way pilot valve in the position shown, the same work with the ordinary one-way valve) 2-way valve into the lower column, column The cavity of the emulsion valve 8 through the two-way valve a back to the liquid, the column extends, to achieve elevated. When the top beam contacts the top plate, the pressure in the lower chamber of the column rises to the unloading pressure of the pump station, the pilot-operated one-way control valve group with the pilot- The pressure of the lower chamber of the column rises to the setting pressure of the relief valve, the relief valve opens and unloads, and the pressure in the lower chamber of the column is reduced again. As a result, When the lower column pressure drops to the relief valve closing pressure, the relief valve and closed. Thereafter, the above process will be repeated so that the pressure in the lower chamber of the column changes in the vicinity of the setting value of the relief valve, and the holder operates in a constant-resistance support state. Due to the fast response speed of the cartridge valve, the pressure in the lower column of the column is small and the support of the stent is good, which is good for the roof management. The system also achieved initial support, resistance increase and constant resistance in the process of lifting the support. The size of initial support force is determined by the pressure of the pump station, and the size of the work resistance is determined by the pressure setting of the relief valve. (2) lowering rack When the solenoid valve 2YA of the pilot valve in the cartridge type directional control valve 8 is energized, when the 1YA is de-energized, the valve is switched to the right position and the pressure in the upper chamber of the four two-way valves, a and c, , In the closed state, b and d on the chamber through the tank, in the open state, the pump pressure provided by the two-way valve b into the upper chamber, while the pilot-operated valve in the pilot valve to the right position , So that the two-way valve on the chamber through the tank, in the open state, the lower column of the oil through the hydraulic control check valve in the two-way valve back to the column retracted to achieve reduction. After the descending frame, the pilot valve in the directional valve is placed in the middle of the diagram (both 1YA and 2YA are off). At this time, the upper two chambers of the two two-way valves are closed with pressure oil and the two The cavity oil circuit is also closed, the stent stays in a certain height position, ready to move (3) push and move the jack pushed jack action by the cartridge-type directional control valve 9, when the pilot valve in the directional valve Right (4YA power, 3YA power) and left (3YA power, 4YA power off), respectively, control the displacement of the jack piston rod out and retract, to achieve push and slip and move the shelf. Pushed the action is completed, the pilot valve will be placed in the middle (3YA and 4YA power), 4 two-way valve e, f, g, h on the cavity are pressure oil in a closed state, pushing the jack of the two chamber oil The road is closed, the move stopped. After receiving the new command, the carriage will start the next cycle of motion. When the solenoid valve in the directional valve is replaced by a manual valve, the hydraulic system of the existing manual control mode bracket can be designed by using the cartridge valve to improve the workability of the bracket and improve the reliability of the work. The analysis shows that the hydraulic system of the electro-hydraulic control bracket designed by the cartridge valve can meet the work requirement of the bracket. Based on the same principle, the hydraulic system of all types and models of hydraulic support can be designed by the cartridge valve. 3, feasibility analysis (1) cartridge valve performance characteristics suitable for hydraulic support conditions, to meet their requirements. (2) The functions of various valve elements used in the hydraulic system of modern stents can be realized with the corresponding cartridge valves. The hydraulic system of all types and models of electrohydraulic control brackets can be designed with cartridge valves. (3) The advantage of easy integration of the cartridge valve allows the structure of the control valve cartridge to be compact and easy to install. (4) There are mature electro-hydraulic control system and explosion-proof electro-hydraulic control components available for selection. (5) Cartridge valve element production has become a series of generalization, manufacturing and use of relatively low cost. The design and assembly of the support hydraulic system with cartridge valves is technically accessible and economically viable. 4 Conclusion (1) plug-in valve to facilitate the realization of electro-hydraulic control, flow through the advantages of large capacity and fast response to adapt to the use of electro-hydraulic control of the hydraulic support conditions, with its designed stent hydraulic system, superior performance, to meet the use Requirements and the need to move quickly to facilitate universalization, serialization and standardization. (2) cartridge valve excellent sealing performance, more suitable for use in pure water medium pure water stent. (3) cartridge valve anti-pollution ability, when the media is dirty, not easy to block, wear less, can extend the service life of valve components, reduce failure and improve the reliability of hydraulic support system. (4) The hydraulic system of the electro-hydraulic control bracket is designed by using the cartridge valve, which accords with the production requirements and meets the development trend of roof support technology and fluid transmission technology of fully mechanized coal mining face. It is technically accessible, economically feasible and worth promoting.