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Pilot pressure valve structure and function as well as features
Abstract: This paper introduces the best structural mode of pilot pressure valve, which has excellent accuracy and stability. This mode can be used in the conventional pilot relief valve. The sequence valve and pressure reducing valve are unified as a pilot pressure valve with a common pilot valve. Key words: Pilot pressure valve; Optimal structure model; Precise zero-difference control; General-purpose pilot valve; Maximum value of stability margin 1 Introduction The existing pilot-operated pressure valve mostly adopts the mode of introducing technology. Here is a description of the best structure model (patented), its accuracy and stability is excellent. Conventional pilot-operated relief valves, sequencing valves and pressure relief valves have been modified to be pilot pressure valves with a common pilot valve. 2 Pilot pressure valve structure, function Figure 1 is a pilot relief valve relief valve structure, the relationship between the parameters as follows: Kt2 (Y20 + Y2) = p1A2-Ky2Y2p2-Fr2Q = KQY1p1Kt1 (Y10 + Y1) = (p1 - p2) A1-p2 (A3-A1) -Ky1Y1p1-Ff1q = KqY2p1 / 2-qjq = Kd (p1- p2) 1 / 2d2e where Kt2, Kt1- spring rate of the main valve Y20, Y10- Pilot valve, the main valve spring pre-compression Y2, Y1 - pilot valve, the main valve opening p2, p1 - pilot valve port, the main valve port pressure Ky2Y2p2, Ky1Y1p1 - pilot valve, the main valve of the steady state Hydraulic power Ff2, Ff1-- pilot valve core, the main spool friction q, Q - pilot valve, the main valve of the flow KQ, Kq, Kd - structure constant qj - pilot valve guide piston clearance leakage (Small value) A2, A3, A1 - Cross-sectional area of ​​pilot valve port, main spool and main port de - Main valve differential pressure damping orifice The pilot flow of the pilot pressure valve is made through a separate orifice E Valve pressure, the size of the orifice (does not affect the pressure wave transmission speed) has nothing to do with the dynamic characteristics. The pilot valve core and the main spool have their own special orifice D and F to control the smoothness of its action, the size of its damping orifice (affecting spool movement speed) does not affect the pressure regulation accuracy. Pilot valve directly driven by the control pressure, no partial pressure loss; pilot valve opening pressure will be lower than the opening pressure. Control pressure to open the pilot valve after the pressure increase that is the pressure difference, which directly determines the pilot valve opening, so its value is only a few atmospheres, much smaller than the conventional structure. When the pilot valve port opens, the pressure will be lower than the pressure when the pilot valve is opened, so as to minimize the pressure drop at the pilot valve port. The main valve plug is fully promoted by the pressure difference generated by the control flow and there is no partial pressure loss. Control flow mainly in the main spool between the front and back chamber and the pilot valve port at the pressure drop, the former great pressure (damping orifice E can take the minimum), the static characteristics can achieve the best value. Differential orifice size is the key factor that determines the amount of control flow required. The pilot pressure control valve pressure directly determines the pilot valve opening, and the three damping holes completely separate, can play their own functions to the extreme. Therefore, its structural model is the best. The pilot pressure valve opening process is as follows: When the control pressure increases, to open the pressure, the pilot valve open, resulting in control of flow. Control flow through the main valve differential pressure orifice to form a pressure drop. Control pressure continues to rise, the pilot valve opening continues to increase, the control flow continues to increase, the main valve differential pressure orifice pressure drop continues to increase, when the pressure reaches the main valve opening pressure to full open pressure, the main spool is Lift until it opens enough to pass the rated flow. 3 Pilot pressure valve performance characteristics 1) can be accurately controlled based on imported structural mode, maintain its installation, connection size, pressure level series, diameter series and the size of the orifice unchanged, the best mode of transformation, the same period last year Regulated pressure difference is only imported 0.1 to 0.2, if the pressure differential orifice reduced to import imports of 0.05 to 0.1. When system cleanliness is high, pilot valve opening is allowed to be small, the best mode pressure difference is minimal (zero difference in engineering). Therefore, precise control is possible. 2) Pilot valve can be realized as a result of the pressure difference is small, if the uniform design of a low stiffness, high strength large amount of compression spring valve, but also cancel the pressure level series, the conventional pilot-pressure valve unified Best Mode Pilot Pressure Valve with Universal Pilot Valve. 3) great stability margin, excellent anti-vibration and noise reduction If the pilot valve in Figure 1 to conduct a comprehensive transformation to increase the spring-oriented sleeve to prevent the pilot valve core radial vibration, vibration and noise reduction, the guidance Sleeves have "Fuzheng" power, while the special damping holes D and F are "evil" effect. To meet the rapidity of the premise, D and F damping aperture should be the minimum. In this way, great stability margin, excellent anti-vibration and noise reduction. Due to the presence of the guide sleeve, the pilot valve steady-state hydraulic power is negligible. In this way, you can set the pilot valve opening Y2, according to the required known technical requirements, from equation (1) ~ (5) (excluding friction and qj) can be followed by control pressure p1, the main valve opening Y1, pilot valve port pressure p2, the control flow q and the main valve differential pressure damping aperture de. 4) Structure can be further optimized In order to facilitate the detection of pilot valve open, but also to make the main valve components are interchangeable, the main spool and the valve sleeve can be further used between the combination of low friction seal.