, Hlob J-l Phanh bao hi~m kieu kim.
§3.3 TINH CHQN CCNG SUAT DONG CO TRUYEN DONG THANG MAy
DONG CO TRUYEN DONG THANG MAy
D~ dnh chc;m d11QC cOng su!t dQng co truy~n d¢ng tbang may clin cO cac di~u ki(!n vA tham s6 sau :
- So d6 dOng hQc cua thang may - T6c d¢ vA gia t6c Ion nhl'lt cha phep - TrQng tAi
- Tr~mg 111c;fng pu6ng thang.
COng su!t tlnh cua dOng 00 khi nAng tai khOng dung d6i tI"Qng d11QC dnh thea cOng thuc sau :
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Trang d6 Gbl - kh6i hlQng bu6ng thang [kg] G - kh6i hlQng bAng, [kg]
v - t6c dQ nAng, [mls)
g - gia t6c tl'Qng tr11bng, [m/s2]
rz - hiQ:u suAt cUa CO" Cl1u nAng (0,5 + 0,8).
(3-1)
Khi c6 d6i trQng, cOng su!t dnh cUa dOng Cd 11k nAng tl\i dl1QC dnh thea bi~u thuc sau : Pen = {[G + GbtJi - Gdt.rz}vkg.1O-3, [kW]. (3-2) VA khi hl;l tAi
(3-3) Trang d6 : Pen - cOng su!t dnh cua d¢ng 00 khi nAng co dung d6i trQng Trang d6 : Pen - cOng su!t dnh cua d¢ng 00 khi nAng co dung d6i trQng
P eh - cOng sul'lt dnh cua dQng 00 khi hl;l co dung d6i trQng Gdt - kh6i 111Qng cua d6i trQng, [kg]
k - ~ Oil tlnh Mn rna sat gifta thanh WIn bUbng va d& tn,mg (k = 1,15 + 1,3). Kh6i 111c;mg cua d6i trQng dl1QC dnh thea bi~u thuc sau dAy:
Gdt = Ghl + aG, [kg]. (3-4)
;
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Phlin 16:n cac thang mAy eM khach chI v$,n hAnh dl1y titi trvng nhung gtb can di~m, thOi gian -dm l~i luOn lam vi~c non tAi ; cho n€m d6i vdi thang may cha kMch n~n ChQD M a6 a ::= 0,35 -I- 0,4.
D6i v{Ji thang may chc'J hllng, khi nling thllbng IS. diiy tl).i vii khi hl;l thu:bng Iii. khOng
tAi, nlm chc;m a = 0,5.
D\ia t~n hai bi~u thuc (3-2) va. (3-3) c6 the xAy dl,1'ng dllt;JC biell dfi ph\! tAi vA chc;m ad bl) cOng sullt cua dOng co thea s6 tay tra CUll.
Mudn xAy d\ing bi~u d6 ph1,l tAi chtnh xac, din phAi dnh d~n thbi gian rna may, thbi gian hl1m, thai gian dong, rna cua va 86 IAn dling cua bu6ng thang khi chuyen dl;lng.
ThOng s6 tllCfng d6i M tfnh toan cae thai gian trlln dllQ'C dua ra trong bAng 3-1. Thbi gian ra, vAo bu6ng thang dllQC dnh gl1n dung ls/l ngubL 86 lAn dung (dnh thea XBC su.!It) eua bu6ng thang co the dm thea cae dubng cong tr€!n hlnh 3-3.
T6e dO di ehuyen (m/s) 0,5 0,75 1,0 1,5 2,5 3,5 18 16 14 12 10 8 6 4 2 V V Bimg 3-1
Thbi gian rna may T6ng thbi gian cOn l~i (8) vii hl1rn may v(1i khoang
Bu6ng thang Bu6ng thang Bu6ng thang each giua ella Ung (s)
cd ci'ta r¢ng co etta r¢ng e6 ella rOng 3,6 met .. 7,2 met duili BOOmm dulli BOOrnm dulli 1000mrn
(md bAng tay) (meJ t~ dQng) (rna tV' dOng) , 1,6 1,6 12,0 7,0 - 1,6 1,6 12,0 7,0 - 1,8 1,8 13,0 7,0 6,3 1,8 1,8 - 7,2 6,3 2,8 2,0 - - 6,5 3,2 2,5 - - 7,0 --- E 21n uai / ' .-- E-1 ngui / " ..------ .<,. r" E 13ng yo; f;:: / E lOng 0/ :----.-- E 5nau '; 5 10 14 18 22 26 30 34 38 42 46 50 m,
Hlnh 3-3. Dl1dng cong de x.IIc dinh ~ illn dung (thoo xAc suJll) Clla bu6ng thang. md - sO lIin dung; rn,. - s6 tA:ng ; E - s6 ngtlOi lrung bu6ng thang.
31
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Phuong phap dnh ch!;m cOng Built d¢ng CO truy~n d¢ng thang may til!n hanh theo cac bulic sau dAy :
1. nnh IIjC kea d~t len puli cap kea bu6ng thang a tAng dulii dmg va cac IAn dung ti@'p thea :
Trang do :
kl - s6 llin dung cua bu6ng thang.
6.G1 - thay d6i (giam) kh6i h1Qng tM sau m6i hin dung. g - gia t6c tr(;mg truong, [m/s2].
2. Tlnh m6men tuong ung vai lljc kea.
M F.R i.I[ , [Nm] nl!u F > 0
va : M ~ -,-12 , F.R . [Nm], n@'uF<O. Trang dci R - ban kfnh cua puli, [m].
i - ty 96 truy~n cua cd ~u.
'1 - hi~u sucH cua co cAu.
(3-5)
(3-6)
3. Tfnh t6ng thbi gian hanh trinh nAng va h~ cua bu6ng thang baa g6m : thai gian bu6ng thang di chuyl!n vai t6c dQ 6n dinh, thbi gian rna may va hlim may va t6ng thai gian ron l~i (thai gian dong rna cua bu6ng thang, thbi gian ra vao buang thang cua hanh khach) thea bang 3-1.
4. Dy-a tr~n k@'t qua cua cac buac tlnb tmin tr~n, tinh mO men dAng trj va tinh chon cOng sullt de)ng cd.
5. XAy dljng bi~u do ph1,l ali chlnh xae cua de)ng cd truyl'!n. de)ng co tlnh den cae qua trinh qua de) va ti@'n hanh ki@'m nghi~m cOng sullt dQng cd dli ch<;>n thea di~u ki~n phat nong, qua till.
§3.4. ANH HuUNG ellA Toe DQ, GIA Toe VA DQ D~T (DAO HAM
B~e NHAT ellA GIA TOC) DOl veil He TRUYEN oQNG THANG MAy
M9t trang nhung y~u cAu Cd ban d6i vOi M truy~n d¢ng thang may la ph!ll dam baa cha bu6ng thang chuyEfn d¢ng ~m. Bu6ng thang chuyEfn dOng Elm hay khOng, ph\! thu¢C vao gia t6c khi md may va khi hlim may. Cac tham 56 chlnh d~c t:rung cha ch~ dO lam vi~c cua thang may Ia : t6c d¢ di chuyEfn v[m/s], gia t6c a[m/s2] va de) d~t p[m/s3).
T6c de) di chuygn cua bu6ng thang quy~t dinh nling Built cua thang may, cd y nghta quan tI'Qng, nh:H la d6i vai cac nha cao bing.
D6i v6"i cac nha ch9c trbi, t6i uu nMit la dung thang may caa t6c (v = 3,5m/s), giam thbi gian qua de) va Wc d¢ di chuygn trung binh cua bu6ng thang d{lt gAn bAng t6c d() dtnh muc. Nhung vi~c tling t6e de) l{li dAn d~n tling gia thlinh eua thang may. Neu tang 32
'.
t6c d¢ cua thang may v = 0,75m/s Hln v = 3,5m/s, gia thanh tllng Illn 4 + 5 ll'in. Bai v1).y, tuy thea d¢ caa cua nha rna chQn thang may co Mc d¢ phil hc;Jp viii t6c d¢ t6i uu. T6c d¢ di chuy4!n trung blnh cua thang may cd th4! tAng bAng clch giAm thOi gian rna may va ham may, cd nghla IA tAng gia t6c. Nhung khi gia t6c IlIn sll gAy ra cAm giac khd chju cha hAnh khach (nhu chdng m~t, SQ hAi, nghfilt tho v.v ... ). Boi v$.y, gia t6c t6i uu la a :!iO 2m/s2.
Gia t6c t6i 11u dAm bAa na.ng suAt caa, khOng gAy ra cam giac kh6 ch~u cha hanh khach, d11QC d11a ra trong bAng 3-2.
Tham s6
Tt'lc d¢ thang may (m/s)
Gia t6c cl,1c d~ (m/s2)
Gia Me dnh toan kung binh (m/s2)
I '-' , 0 '-' , 0 !-_I- 'I I , I , Xaay chi~u 0,5 0,75 1 1 0,5 0,5 s H~ tTUy~n d¢ng 1 1,5 0,8 M¢t chi~u 1,5 1,5 1 p r- , I 2,5 2 1 Bang 3-2 l' n , I 3,5 2 1,5 Q~I~~~ _ _ _ _ _ _ ~~~~=+~t_ J. ~Bf)i)l ·i. , , L.,J P
Hloh 3-4. Cae dlldng cong bit!u dil'n sl,l ph1,l tln.tOe ella quAng duong S, Ide d¢ v, gia 16e a va dO del P thea thOi gian.
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M~t dl.li hrc;mg nua quyl'lt d~nh sl,t di chuy€n €lm cua bu6ng thang la t6c dQ tAng cua gia Mc khi mc'.! may va t6c d9 giam cua gia t6c khi ha.m may. Noi mtit eAch kM.c, do Iii
da d2v
d¢ ~t (~l.lo ham b~c nhc'(t cua gia tOe f = dt hoi;1c ~ h8rn. ~ hai ella. t.6c dti f = dt2 ). ,Khi gia t6c a ~ 2m/s2 thi d¢ d~t kht"lng dUQc qua 20m/s3.
Bh~u d6 lam vi~c t6i uu cUa thang may USc d9 trung binh va t6c dO cao bi€u di€n tr€ln hlnh 3-4.
Bieu d6 nay co th~ chia ra lam 5 giai dOl.ln thea dnh chllt thay d6i toc dti cua buang thang : ma may, che dti On dinh, M.m xu6ng t6c d() thllp, bu6ng thang den tAng va
ham dung.
Bi~u d6 t6i uu hlnh 3-4 se dl;it dUQc n~u dung M truy~n d()ng mtit chi~u (F-D). Neu dung M truyen d()ng xoay chieu vlii d(lng co kht"lng d6ng b(l hai cap t6c dQ, bi~u d6 chi dl.lt gan giOng bi{!u d6 t6i uu.
Doi voi thang may chl;iy ch~m, bi~u d6 chi c6 ba giai do!pl : mo may, chI'! dQ 6n dmh va ham dung.
§3.5. DlrnG CHINH xAc BUONG THANG
Bu6ng thang cUa thang may cAn phai dting chinh xac so voi m~t bang cua Uing cAn dung sau khi iln nut dung. Neu buang thang dung khong chinh xac se gay ra cac hi~n tUQng sau :
- D6i v6i thang may cha kMch, lam cho hanh khAch ra, vao kho khAn, tAng- thai gian re, vilo cua hanh khach, dAn d~n giam nAng suilt.
- D6i v{Ji thang may chb hang, gAy kho khAn trong vi~ xep va Mc da hang. Trang mtit s6 trubng hQP c6 th~ kht"lng tht,!c hi~n dUQc vi~ x~ vA Mc da hang.
D~ kh~c phl,lc h(,-u qua do, co th€ c'(n nhAp nut ba:m d~ df).t dUQc dti chinh xac khi dung, nhung se dAn Mn cae vc'(n de kh6ng mong mu6n sau
- Hong thi(~"t bi di~u khi~n - GAy t6n th!t nling lUQng - GAy t6n th!t nling lUQng
- GAy h9ng hOc clk thi~t hi Cd khi - TAng thbi gian tu luc ham d~n dung.
D~ dung chinh xlie bu6ng thang, din dnh den m(jt ntra hi/[!u 56 cua hai quang duang truQt khi phanh buang thang dc'(y Uti va phanh bu6ng thang kht"lng tAi thea cung mQt huang di chuy~n. Cac yeu to anh huang d~n dung chinh xac bu6ng thang bao gam : momen cua co cllu phanh, mt"lmen quan dnh cua buang thang, t6c d¢ khi b~t dAu ham va mOt s6 yeu to phl,l khac.
Qua trlnh ham bu6ng thang xity ra nhu sau : khi bu6ng thang di dlin gan san tang, dIng tAc chuy€n d6i tang dip l~nh Mn h¢ th6ng dieu khi~n d(lng cd d~ dung buang
'.
thang. Trang quAng thbi ,gian 6.t (thbi man tac dQng cua thi~t bi di~u khi~n), bu6ng thang di dUQc quAng dubng IA
S' = voAt , [m] (3-7)
Trang d6 : v 0 - T6c dQ hic bAt dllu ha.m, [m/s].
Khi co c!1'u phanh mc dQng IA qua trlnh hAm bu6ng thang. Trong thbi gian nAy, bu6ng thang di dUQc m¢t quang duong S".
mv'
S" = 0 , [m]
2(Fph ± FJ (3-8)
Trang do : m - kh6i IUQng cAc phl1n chuygn dQng cua bu6ng thang, [kg] F ph - h,1c phanh, [Nl
Fe - h,1c can dnh, [N]
Dau (+) ho~c tru (-) trong bieu thuc (3-8) phl:l thuQc va~ chh~u tac dvng clla h,tc
Fe: Khi bu6ng thang di l@n (+) va khi bu6ng thang di xu6ng (-). S" cung cd the vi~t duO'i df).ng sau :
S" = (3-9)
Trang do : J - mOmen quan dnh M quy d6i v~ chuy~n d¢ng Clla bu6ng thang, [kgm2] MPh - momen rna sat, [N]
Me - mOmen can tlnh, [N]
Wo - Mc dQ quay cua d¢ng co Iuc bAt dl1u phanh, [rad/s] D - dubng klnh puli keo cap, [m]