ABSTRACT
A :cross sectional area of flowmeter A c:control chamber area of main valve Ap (Apm) :pilot valve opening area(m:max.) A s:supply pressure acting area b:damping coefficient of flowmeter spool C d:discharge coefficient Ft:flow force kl. k2:spring constants L: length between inlet and outlet port m:mass of flowmeter spool mt:mass of workig fluid moving with spool P c:pressure at control chamber
P L: load pressure P s: supply pressure Q:flow rates Q c: flow rates through feedback slots QL:load flow rates Qp:pilot flow rates t p:PWM width t s: PWM carrier nrc:width of feedback slots x:lift of main seat valve XL:underlap of feedback slots y:displacement of flowmeter spool p:fluid density z:-:PWM duty (= t p/ t s)
