Thit k chn vt s dng ht cng sut my
T cc gi tr D, H/D, p , N e tnh c bng 3.2 ta xy dng th biu th s
ph thuc ca chng vo tc quay ca chn vt ncv (Hnh 3.1).
T th, xc nh vng ng knh chn vt c th ch n cho tu thi t k t gi
tr D Dmax . Sau , tin hnh bc chn my chnh.
m b
Cc h s nh hng ca thn tu
H s dng theo
H s dng theo l t s gia tc ca dng theo v tc tu:
C
V
(3.4)
Trong :
C Tc dng theo, m/s;
V Tc tu, m/s.
H s dng theo ph thuc ch yu vo hnh dng ui tu v kh xc nh m t
cch chnh xc.
Do , n thng c xc nh theo cc cng thc gn ng.
Cn
Xy dng c tnh thu ng hc ca chn vt trong nc t do
Mc ch ca vic xy dng c tnh thu ng ca chn vt trong nc t do l
gip cho vic nghin cu s lm vic ca chn vt cc ch khc vi ch tnh
ton.
Trnh t tnh theo bng 3.5.
Bng tnh xy dng c tnh thu ng hc ca chn vt trong nc t do
TT
S phi hp lm vic gia c tnh ng c v c tnh chn vt
c tnh ng c v c tnh chn vt. Min cng sut s dng v min cc ch lm
vic ca lin hp My Thn tu Chn vt
1- c tnh ngoi cng sut cc i.
2- c tnh ngoi cng sut nh mc.
3- c tnh ngoi cng sut vn hnh.
4- c tnh gii hn theo mmen xon (
THIT K THIT B NNG LNG CHNH TU C
Nguyn tc chung ca vic thit k t hp ng c Truyn ng Thit b
y
Chn cng sut ng c chnh
Cng sut ng c chnh c xc nh trong qu trnh tnh ton thu ng chn
vt trn c s sc cn thn tu chuyn ng trong n c v t c ch y tu. Vi c xc
nh cng sut ng c chn
Chn cc thng s ban u
- Chn Z v ca chn vt
- Chn h s dng theo v h s dng ht t. Tnh kim tra hiu sut thn tu K .
- Tc quay ca chn vt ncv , v/s.
*
*
- Cng sut truyn n mt trc chn vt N D N e hs t mt ( N p N D K R - xt ch
nh mc).
Thit k chn vt s dng ht cng sut my
T
Xy dng th biu th mi quan h
*
T trc N D , ta t tr s N D N e hs t mt (xc nh v tr), ri k qua ng
song song vi trc honh, ct ng N D f V ti mt im. Qua im , ta k
ng song song vi trc tung, ct trc honh v cc ng D f V , p f V ,
H D f V .
Cc giao im y cho ta tr s cc t
Xy dng c tnh chn vt
Mc ch ca vic xy dng c tnh chn vt l kim tra s ph h p gi a t
My V Chn vt cc ch lm vic: ch hng hi t do, ch ko li v
ch buc tu.
Khi tnh ton cn ch cc thng s khc bit sau:
- ch hng hi t do: p p tt ; t t tt .
- ch ko li: p
p tt
2
; t t KL ;
Nguyn tc chn v tnh cc thng s ban u
i vi tu nh c li ko trang b chn vt nh b c c 3 xu h ng thi t k
chn vt:
a)- Thit k chn vt theo ch hng hi t do. R rng trng h p ny chn vt
b nng thu ng khi lm vic ch ko li. y l xu hng ca Lin X c.
b)- Thit k chn vt theo ch ko
Thng s cho trc
Cng thc ca Heckscher i vi tu li ko:
t 0,7 7 0,30
(3.13)
Hoc c th xc nh t theo cng thc sau:
t q
(3.14)
Khi bnh li c dng lu tuyn th q (0,7 0,9) .
Trng hp chn vt lm vic ch khc vi ch tnh ton c n xc nh t
ph thuc vo bc trt tng i p hoc h s trt the
Tnh v chn cc thng s ban u
- Chn thng s Z v ca chn vt
- Xc nh h s dng theo v h s dng ht t. Tnh kim tra hiu sut thn tu
K (1,01 1,06) .
- Xc nh ng knh cc i ca chn vt.
- Xc nh sc cn thn tu ng vi tc tu cho trc.
- Tnh lc y ca chn vt:
P
R
P
e , kG
1 t 1 t
- Tn
