Chapter 7 Flow Control Valves and Other Hydraulic Valves.pptVIP

* Chapter 7 Flow Control Valves and Other Hydraulic Valves Objectives: The purpose of this chapter is to describe: 1. Operation of flow control valves, cartridge valve, proportional valve and servo valve. 2. Throttle valves, combined flow control and check valves, flow regulating valve , flow divider, cartridge valve, proportional valve and servo valve. 3. Applications of flow control valves, cartridge valve, proportional valve and servo valve. Upon completing this chapter, you should be able to: Explain the operation of the various types of control valves. Identify the graphical symbols used for flow control valves. Master the characteristics of cartridge valve, proportional valve and servo valve. 7.1 Throttle valves 1 Characteristics of throttle orifice q Δq2 Δq1 Conclusion: Thin-wall orifices should be used for throttle orifices 7.1 Throttle valves Figure 7.2 throttle valve Figure 7.3 throttle valve with a with axial vee notch orifice spiral curve and thin bladed notch 1.top cover 2.guide sleeve 1.hand wheel 2.spool 3. valve body 4.spool 3. valve pocket 4. valve body 5.spring 6.bottom cove 2 structure 7. 2 combined flow control and check valves Figure 7.4 flow control and check valve 1.top cover 2.guide sleeve 3. upper spool 4.lower spool 5 valve body 6. return spring 7. base plate 7.3 Flow regulating valve 1 Problem The pressure drop variation of a throttle valve has great influence on its flow stability. 2 Measure methods of some physical parameters (1) pressure measure (b) pressure sum measure (c) pressure difference measure How to remove the influence? The solution is to add a correction loop. 7.3 Flow regulating valve The valve consists of a pressure reducing valve and a throttle valve in series, where the former maintains a constant pressure difference. 3 construction of a flow regulating valve A signal