I 1.1 v J \)v \J b) Tdn s(f
u Sam btl1'n lhi!n 1 plslon ,
Sam btl1'n lhi!n. 1 plslon ,6
Hydro -motor c6 dinh
Hydro -moIor bien !hien
Xitanh 1 chieu Xitanh 2 chieu o .0 I I I I
Xilanh vOi lay keo vi sai ~I, II JI ~~I;= B¢ khufcll dOl ap [ I r=n-
Sinh Uch man cnan-ap gas
Sinh tich ap gas 8 §
b) Mi}t sf; ki IlIfli clia cae bl) IJhljll kMc
tinh gifra utiu vim va dau ra, diii ehet (dead band), bang thong (bandwidth). Van ti l~ e6 th~ chia ra 13. ti l~ eho dong ho~c ti I¢ eho ap. Nha c6 selenoit pMn (rng ti I~ voi sl.! thay doi ell.3 tin hi¢u den nen van cap dau ra thuy il.!e (ap, dong, huang, gia t6e, giilm t6e .. ) tucmg Ung "min".
Ki hi¢u van
Ki hi¢u guy djnh eha van dieu ehinh tip th~ hi~n trong hlnh 2.42a, trang d6 cae hlnh vuong 1.1 de vi tri ehuy~n mQ.eh. Hinh 2.42b th~ hi~n mQt s6 kf hi~u kh,ic dung eha d(>ng co, born. v ... v. Trang hlnh 2.43 con th~ hi~n m(>t s6 phucmg phap di€u k.hien v~n hanh van. Nhu v~y neu van co 2 vj tri thi kf hi¢u van se co 2 kh6i vuong. Vi dl:!, uicu khi~n v~n hanh van vui num dAy (hlnh 2.44a: van
cAe PHlJONG PHAp DltU
KHI~N
Chat
Thu cbng
Cakhi
NLim d~y
Canh tay don
Ap pilot Solenait Ap pilot- s6lenoit Lo xo ~ =C f:=[ =C 8 C[ CE[ cQ ~ MV[ Dieuchil1h ti 1$ dong : ~ thay doi LLtL VAN CHjNH HUONG Van 212 Van 312 Van 412 Van 312 Van 213 Van 413 (dong gilia) Van 314 (P n6i T crv! Irf gilia)
Van 413
(P,A &8 den Ihung chua crvi In gil1a)
lIinh2. 43: Ki hifu cac van ehlnh hmlng va cac ki hi¢u die"1I khilll vr;1n helnlt \'an
4/2), khi num day dtIqc nhan, piston tien. Sl,l" ehuyen dQng cua mlm day t<;1O tr<;1ng thai nhu hi~n thl boi cae kf hi~u duqe su dl;mg trang hinh vuong ben trai,
tue dong ehat hru tien theo c6ng P-B, hoi thea duemg A-1'. Khi nhi num , 10 xo day van trC1 ve vj trf ban dall va piston lui. TtIang 11!, v6i di~u khi6n s6len6it (hlnh 2.44b), khi eo dong di~n qua salCnait , piston tien, khi huy dong, 16 xo keo van ve vi tri" ban dau va piston th1.fe hi~n lui. Chuy6n d¢ng ella 10 xo tlj.o nco trlj.ng thai ella van nhu th~ hi~n ttong hinh vuong ben phiii.
2.4.2.4. Ki~u van
M6t s6' kiiu van die"u ehtnh.
dlj.ng dan giin thuang duqe su d~ng trang h~ 13:
+ Van ddy (poppet valves)
duqc th6 hi¢n il hinh 2.45, binh thuemg C1 trlj.ng tMi dong. Trang van, cae bi, dia ho~c dau con lien ket voi vi tri d~t van (valve seat)
d6 dieu ehinh lUll IUqIlg, vi dl,l, khi nhan buton, bi duqc keo khoi vi tti ella n6 de dong qua. LOlj.i van nay e6 the 13. duVe dan (Pilot
-operated), khi Il,l"e yeu cau dong bi 160 (ttong h~ thong van duqc
dan (Pilot - operated sytem), ngl1Cri ta sit d~ng van dan de dieu khien van thtl hai -van ehinh. Van dan thuang c6 eang suat nho va c6 the v~n hanh thtl eong ho~c bC1i solenoit). Van poppet eo the
la van crunh hu6ng (directional), eho phep dong chuyen d¢ng thea
AI is \ ( ' II I ()l / , ,) , " P ·.T b) ifWV I
Hinh 2.44: Van 412 a) dilu khiln viii num ddy b) die"u khie"'n va-i silinait
0 r1 Il~n " I r;-' .J:! ,~l I , I, I I
Hinh 2.45:Van ddy
I I j
Hinh 2.46: Vall o'ng
r
'i t ~ " I I I
! ~, ~I IT ~I IT
mQt hl16ng, ho~e la van an toan- xd ap (presure relief valve) c6 16 van blnh thuemg dong va ehi mil khi ap trong h¢ thong Vl1qt qua gia tq thiet If).p.
+ Van o"ng (spool valve) c6 mOt aog cuQn chuyen d¢ng ngang trang than van cte di~u khien hru hrqng. ffinh 2.46 tM hi¢n hlnh dr,tng ella m9t van ong 4/2. Nhu trang hlnh, B duqc n6i vai P khi A va T dong. Khi 6ng cu(m chuy~n ve ben trai, A duqc n6i v6i P va B, T duqc dong. Ong cUQn co the: dlIqc day bili mim
day, canh tay don ho~c solenoit. Van {/ng CUQfI quay (rotary spool valve) c6 rnQt 6ng cUQn quay. Khi ong quay, d.c cang duqc d6ng ho~e duqc rna theo each tu'cmg tl! nhau. Van ang thuemg duqc Slr dl,lng trong cac van dan hudng.
2.4.2.5. Thanh phan kfch truyen dQng (actuator):
Kich truyln dQng lruyi'n thang: xilanh khi min hogc xilanh lhuy ltjc Iii vi dl,l ve thanh phan kich -truyen d¢ng thang. Ve nguyen Ii xilanh h¢ thuy II!C va khi nen la tuemg tl!, sl! khac nhau 6 kich thuae do ap a h¢ thuy II!C cao hem. Xilanh thuy II!C la rn¢t ang r(jng, trong do piston co thi truQt dQc. Hinh 2.47 tM hi¢n hai lo~i xi lanh d~e trung nhat, lo~i hO'l1 d¢ng dup (tac d¢ng hai chieu) va lo~i
hO{l1 d¢ng dall (lac d¢ng rn¢t chieu). Chuy~n d¢ng thang do xilanh thuy ll,fc sinh ra thtICmg duqc Sll dl,lng de v~n hanh van ong.
Vi¢c chQn xilanh duqc
-- I I i
j aj aj
quyet djnh 00i l\Ic yeu d.u d~ch chuyen tai va toc d¢ dieh
chuy~n. Xilanh thuy Ilfc e6 kha
nang truyen life cao han nhieu so vrn xilanh khf nen, Tuy nhien xilanh khi nen l~i cap toe dO djeh chuyen nhanh hon.
TlI b~ di~u k~i~n La ~o
Lifc sinh bdi xilanh lhuy hie: F~A_p
Vdi A la tiet di¢n ngang clla xilanh, p In. ap suat lam viec clla xilanh
Neu toc aQ dong chat long vao xilanh la rn¢t kh6i 111Q'Ilg Q trong 1 gi5.y, piston c6 tiet di¢n ngang A. djeh chuyen rn¢t khoang v trong 1 giay, hie d6: Q=A.v. :::::>
v=Q/A, nhu v~y toc dQ ella xilanh thuy il!c bang luqng chat long Q chia cho tiet di¢n A cua piston.
Toe d¢ eua xilanh khf nen kh6ng the
r 1 .\ .~ "
\
F -, -j , I bl bl
Hinh 2. 47: Xi/anh fhuy lJ/c
a) lac d¢ng hoi chitili b) lac d~ng m¢f chilli
TlI 00 di~u khii!'n
aj bj
Hinh 2.48 :B¢ kich fruyrin d(mg (juay
oj (juay canl! gqf