chap8 flow control val
TRANSCRIPT
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Chapter 8 Flow control valves
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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)
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2) Pressure compensated flow control valve Basic idea : Q constant , indep. of change in P
Principle of operation :
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Neglecting flow force , obtaining the eq. of force equilibrium on the pressure compensator: P1 A=PL A + Ff P = P1 PL =
(B)meter-out
(Ps PL)A= P1 A + Ff P = (Ps PL ) P1= Q constant Ff =k(x0 x ) x
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static performance E4 : due to flow force at large QE1 : due to the characteristic of the original throttle
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(2)(Throttle valve)
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(3)
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1) (free reverse flow)
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2)
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3),
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(two-way) (three-way)(a)Two-way: ()
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(b)Three-way: ()
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(deceleration valve)(a)
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(b)symbols
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(flow divider valves)(a)Flow divider valve with equal flow division
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(b)Priority flow divider valve