Abstract: The emulsion pump station is the power source of the hydraulic support and the hydraulic props of fully-mechanized mining face. Providing work medium such as high pressure and big flow for the system used liquid such as hydraulic support are its responsibility. This paper put forward a system can control the pressure of the emulsion pump station based on electro-hydraulic proportional relief valve. After applying the electro-hydraulic proportional relief valve technique, this system reconstructed the pipeline of pump station. In order to realize the control of pressure, this system used the PID controller in PLC technique to perform logical operations and finally controlled the unload action of overflow valve. This paper give a detailed design of the system, and then build a mathematical model based on the electro-hydraulic proportional pressure control system hardware and analysis the results of control using simulation software.

Introduction

With the continuous development of coal output, underground coal production equipment more perfect, high yield and high efficiency in the comprehensive mining environment is the development direction of coal production. Mining emulsion pump station is the crucial equipment to fully mechanized coal mining. It is the motive sources of the emulsification liquid pump station of single hydraulic prop to fully mechanize or high-grade conventional working coal face and turns the mechanical energy into hydraulic energy by outputting rotating torque so as to drill. In the hydraulic system, a stable hydraulic source is the main factor of a stability system. When the system pressure source appear volatility, the system pressure will happen with fluctuations, even will occur the wave process within the lifting and sharp alternate pressure in the channel. This wave process can damage to sealing device, pipeline and hydraulic components. Even, it cause hydraulic components produce malfunction, so that lead to a major accident. The underground environment of such a high requirements for safety and stability, hydraulic system must be stable, this requires as power sources emulsion pump must provide stable pressure. At present, most of the emulsion pump stations are through various relief valves to realize pressure control, the system under the control of mechanical relief valve, the emulsion pump control range itself changes fluctuation, stability is insufficient, pipeline system more likely to have "critical pipe" phenomenon. According to this phenomenon, the paper puts forward using the electro-hydraulic proportional relief valve instead of mechanical relief valve idea. According to the actual system pressure needs, set up more reasonable pressure rated value, combining PLC with electro-hydraulic proportional relief valve, make the system pressure be close to the setting up value, and finally reach the purpose of constant pressure.  

Applied Mechanics and Materials Vols. 190-191

(2012) pp 860-864 Online available since 2012/Jul/26 at www.scientific.net © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.190-191.860

1 Control system design

At present, due to the increase of underground fluid-used equipment, the emulsion pump is highly demanded more and more. Therefore, it is widely used that the applications of multiple pump in parallel manner. Refer the drowning for knowing the working principle of hydraulic system in figure 1.  

Fig.1 The hydraulic system diagram of emulsion pump 1-the emulsion pump  2-safety value  3-automatic unloading valve group  4-absorbing fluid filters and circuit breaker  5-accumulator  6-aternate globe valve  7-pressure gauge switch  8-filter slots  9-magnetic filter   10-emulsion box  11-absorbing liquid hose  12-the uninstall liquid returning pipe  13-main return liquid pipe  14-liquid-draining pipe  15-the main supplying liquid pipe b-throttle valve  c-pilot valve  d-automatic unloaded valve  e-manual unloaded valve