1. Chapter 8 Flow control valves

2. — limiting the fluid volume flow rate from fixed displacement pumps accurately. — Applications: velocity control of cylinders; speed control of hydraulic motors — ; where Q : volume flow rate to actuator A : effective area of cylinder piston V : displacement of hydraulic motor § Type of flow control valves 1) Throttle valves Non-variable restriction variable restriction(i.e. adjustable) —

3. 2) Pressure compensated flow control valve Basic idea : Q  constant, indep. of change in  P Principle of operation :

4. Neglecting flow force, obtaining the eq. of force equilibrium on the pressure compensator: P 1 A=P L A + F f  P = P 1 – P L = (B)meter-out (Ps – P L )A= P 1 A + F f  P = (Ps – P L ) – P 1 =  Q  constant ∵ F f =k(x 0 – x ) 且 x << x 0 (x 0 : Pre-compression)

5. — static performance E 4 : due to flow force at large Q E 1 : due to the characteristic of the original throttle

6. 流量控制閥：

7. (2) 節流閥 (Throttle valve)

8. (3) 數種常見之節流口

9. 1) 節流閥： ( 具備 free reverse flow)

10. 2) 壓力補償式流量控制閥特性圖：

11. 3) 壓力, 溫度補償式流量控制閥：

12. § 二通流量控制閥與三通流量控制閥之比較： (two-way) (three-way) (a)Two-way: ( 壓力補償桿與節流閥串聯 )

13. (b)Three-way: ( 壓力補償桿與節流閥並聯 )

14. 減速閥 (deceleration valve) ： (a) 結構及工作原理

15. (b) 減速回路及 symbols

16. 分流閥 (flow divider valves) (a)Flow divider valve with equal flow division

17. (b)Priority flow divider valve