NGHIEN c u t ! ANH Hl/ONG CUA CHIEU DAI VA DUONG KINH 6 N G HUT DEN HIEU SUAT LAM VIEC
CUA BOM THUY LUC NGUYEN DINH TiJ Bp mon Mdy xiiy dung - Xep dd Khoa Ca khi
Trudng Dgi hgc Giao thdng Van Idi Tdm tdt: Dudng dng hut Id mot bd phdn ciia he thdng truyen ddng thuy luc, cd anh huong lan den hiiu sudt ldm viic cua bom thiiy tuc ndi riing vd chdt luong ldm viec cua he thdng thuy luc ndi chung. Ndi dung bdi bdo trinh bdy ldm tdt mgt sd kit qua nghiin ciru ciia di ldi NCKH cdp truong md sd T20I3-CK-29 ve dnh hudng ciia chieu ddi vd dudng kinh dng hut din hieu sudt ldm viic cua bam thuy luc.
Summary: The pipes are part of the hydraulic drive system, its have great influence on the performance of hydraulic pumps privately and the all hydraulic .systems generally This paper presents a summary of results of my researches topic number T2013-CK-29 on the impact of the length and diameter of pipes to the performance of the hydraulic pumps.
I. DAT VAN DE
Dudng dng hiit la bd phdn trung gian ket ndi giCra bam thiiy lire va thiing ddu, ddy Id mgt trong nhDng bg phdn khdng the thilu trong he thdng truyin dgng thiiy luc, cd anh hudng rdt ldn dfin hi?u sudt hut va hi6u suat the tich bam thuy luc. Mdt khdc, chi do lam viec ciia bam thiiy luc lien quan true tiep din hieu suat hut, hieu sudt the tich, din dao dgng, mai mdn bl mat cdc thiit bj thiiy lyc,.,. Do vdy, can phai nghien cuu anh hudng cua cac ylu td kit cdu din kha nang hilt ciia bam thuy luc, lam ca sd cho viec lua chgn chieu dai vd dudng kinh ctia dudng dng phii hgp vdi timg logi bam va he thdng thiiy luc khac nhau, Nd giiip cho ngudi thiit kl lya chgn phuang an bd tri dudng dng hut, bd tri bom thiiy lyc trong tuang quan vj tri vdi thiing ddu de bam thiiyyuc lam viec vdi hieu qua cao nhdt Id vdn de can thiet nghien cuu.
II. GIAI QUYET VAN DE
Trong he thdng truyen dgng thiiy luc, vj tri mieng hiit trong thiing ddu cd thi duac bd tri cao han hodc thdp han bam thiiy luc, Vdi viec bd tri thiing ddu d vj tri cao han so vdi bam thiiy luc cho phep tgo ra dp luc d mieng hiit, qua dd nang cao duoc hieu sudt hiit trdnh dugc hien tugng hinh thanh Idc xody ciia ddng ddu nhung cd nhugc diSm Id lam tang dp tuc ddng ddu hdi, ldm gidm luc keo tren dgng ca thiiy luc va dan den tieu hao nhien lieu dgng ca din ddng va lam gidm hi?u sudt lam viec cua bom thuy luc, Ngoai ra, viec thay ddi hinh dgng mieng hiit, sd lugng chd ndi, viec bd tri van, loai ddu cdng tdc,.,, cung lam thay ddi ddng ke khd nang hiit cira bom thiiy lyc.
7 8 Tap chi KHOA HQC GIAO THONG VAN TAI So 50 - 02/2016
Bk lam tang kha ndng hiit ciia bom thuy luc ngudi ta cd thi sir dung nhieu phuang an bd tri dudng dng hiit khdc nhau, cd the siir dung may nen khi. mdng dan hdi hodc tan dung ddng ndng ddng dau hdi,... Mgt sd sa dd bd tri dudng dng hut dugc md ta nhu hinh 1 va hinh 2.
Hinh I. Sa do kit cdu cd sudung mdy nin khi
I Thiing ddu: 2. Mdt thodng: 3 Dudng ddu hdi:
4 Ong hut; 5. Dudng dng ndi vdi mdy nen khi.
6 Thiit bi chia
:^^^^¥=0
Hinh 2. So dd kit can su dung ddng ndng cua ddng ddu hdi I Thiing ddu. 2. Bom thuy lire. 3. (%g hdi.
4 Ong phun: 6 Van an todn: 7. Loc ddu:
8 Ong ddn
Cac gia thiit khi xdy dung md hinh bai toan nghien ciru dnh hudng ciia chilu dai va dudng kinh dng hiit din hi?u sudt ldm viec ciia bam thiiy luc: Tdc dg quay tren tryc bam la khdng ddi;
dng hilt Id cirng tuy?t ddi; dudng kinh dng hiit khdng ddi tren sudt chieu ddi dudng dng; bd qua tdn that ve the tich ciia ddu cdng tac trong dudng dng hiit; do cao mieng hiit so vdi bam la khdng ddi; vgn tdc ddu cdng tac trong thiing Id nhd cd th6 coi bang khdng; mo duyn bien dang dan hdi cua ddu cdng tdc la khdng ddi.
So dd bd tri bom thiiy lyc trong nghien cim anh hudng ciia chilu ddi vd dudng kinh dng hut dugc md td nhu tren hinh 3 va hinh 4.
—7.
111 i l l 11 °
K I
\ >
K>
Hinh 3. Sa dd bam thuy luc f^lnh 4. So do ham thuy luc dgt phia dudi thiing ddu 0, p/,/^ ^^ew ihung ddu
0-0: Mdt cat trin be mat thodng cua ddu cdng tdc irong ihiing. I-1. Mat cdt o ddu vdo cua bom thiiy luc: p„ - Ap .sudt khi quyin: PI - Ap .sudt ddu a miing hut cua bom:
h, - Dp cao mieng hut so vdi bom
Tiip chi KHOA H Q C G I A O THONG V ^ N TAI S6 50 - 02/2016 79
Tir cac gia thiit tren, dp dyng djnh ludt bdo todn nang lugng vilt cho ddng chd\ tai mat cat (1 -1) trong sa dd Hinh 3 dudi dang phucmg trinh Becnuli ta cd:
h^+PiL = l L + i ^ + L i L + b . y 4 , H + k.ii^L (,) pg P-8. 2g- t ^d,. ^'••J2g g dT
Trong cdng thiic tren nhung dai lugng xdc djnh dugc gid trj la po. g. p, v^ K. «(.. b, cdn cac dgi lugng h^, Ic, dc, T^^, xdc dinh theo cdc thdng sd kit cdu ciia dudng dng hut.
Ty trgng ciia ddu cdng tdc dugc tinh bdng ty sd giiJa khdi lugng vd the tich dau cdng tac.
xac djnh theo cdng thirc sau:
Khi tang nhiet dp thi ty trpng cua dku cung tang len va dupe xac dinh theo cong thuc sau:
P20 (3) ' l + |3,(t-20)
T6C dp cua dku cong tac trong duong 6ng htit Vc duoc tinh theo cong thirc:
V c = ^ (4, Luu lugng ciia bam thiiy luc dygc xac dinh theo cdng thirc:
Q h = q b - n h - r i (5) Tl - Hifiu sudt the tich ciia bam, phu thugc vdo kit cdu ciia bam. su hao mdn hay khe hd va
quan trgng nhdt Id do nhdt ciia ddu cdng tdc. Hieu sudt the tich ciia bam thudng dugc xdc djnh bdng thyc nghiem.
Trj sd Reynolds ddi vdi ddng chdy trong dudng dng hut cd the dugc xdc djnh theo cdng thuc:
Re = ^ i i (6) u
(3 ch6 dp chay r6i Re > 2320 khi do K = 0.3I64.Re""-"; ct chj dp chay ting Re < 2320 lihi do A^ = —
' Re
He so dp nhat dpng hpc dupe xac djnh theo cong thuc:
— ( ? ) •
(7)80 Tap chi KHOA HOC GIAO THONG VAN TAI So 50 - 02/2016
Trong dd: p(, - Ap sudt khi quyen (Pa): pi - Ap suat ddu a mieng hiit ciia bam (Pa): p - T\
trgng ciia ddu cdng tdc (kg/m'): p, - Ty trong ciia ddu cdng tac d nhiet dd t (kg/m"'); p:,, - T>
trgng ciia ddu cdng tdc d 20"C; p, - He sd gian no nhiet ctia ddu cdng tdc ("C"');
t - nhiet do ctia ddu cdng tdc ("C); g - Gia tdc trgng trudng (m/s"); h^- Chieu cao mi^ng hiit (m);
It - Chieu ddi dudng dng hiit (m): d^ - Dudng kinh dirdng dng hut (m); v^ - Tdc do ddng ddu cdng tac d cudi dudng dng hiit (m/s); /_^^, - Tdng he sd can cue bd tren dudng dng; ?^ - He sd ma sdt dgc dudng; a^ - He sd Koriolis tinh din anh hudng khdng diu ciia tdc do ddng chdy trong dng trdn, Qe = 1 ddi vdi chi do chay rdi, a^ = 2 ddi vdi che do chay tang; x - Thai gian tinh toan (s);
qb - Luu lugng rieng ciia bam thiiy luc (cmVvdng); nb - Tdc do quay cua bam thiiy luc (vdng/phiit); b - He sd tdn that ke den dnh hudng do nhdt ciia dau cdng tac d nhiJng cho ndi.
Tir (4) cd the xdc djnh dugc dudng kinh dng hiit theo cdng thirc sau:
d,, = 1 . 1 3 . 1 ^ (8)
Trong tinh todn tdc do cua ddu trong dudng dng dugc xac djnh theo day gid trj sau: Vc = 0,6; 0,7; 0,8; 0,9; 1,0; 1,1. 1,2 m/s,
Thay (4) vdo (1), qua bien ddi ta nhdn dugc cdng thirc xdc djnh dp suat d mieng hiit ciia bam thiiy lyc nhu sau:
(9)
Hieu suat hiit ciia bam thiiy luc duoc xac dinh theo cdng thirc sau.
%=-^ < > 0 ) p
Hieu suat the tich ciia bom thu> luc duoc xac djnh theo cong thirc sau:
n.,=#^ (M) Trong dd: p<,p, - dp sudt tdi uu trong dudng dng hiit (Pa); Qd„, - luu lugng dinh mirc ciia bam
thiiy luc (m'Vs): Ob- Luu lugng ciia bam thiiy luc, xac djnh theo cdng thirc (5).
Tir cdc cdng ^Crc tren va thdng qua irng dung phdn mim Matlab - Simulink. tdc gia xdy dyng so dd chuang trinh de khao sat anh hudng ciia cac thdng sd kit cdu dng hiit din hi^u sudt dp sudt ciia bom thiiy luc nhu tren hinh 5,
Tgp chi KHOA HOC GIAO THONG V^N TAI S6 50 - 0 2 / 2 0 1 6
Hmh 5. Chuong trinh khao sdt dnh hudng cua dirdng dng hut den hieu sudt hut cua bam thuy luc trong Matlab-Simulink
III.VIDUAPDUNG
De nghien ciru khao sat danh gia anh hudng ctia cdc thdng sd ket cau dudng dng hiit den hieu sudt ldm viec ciia bam thiiy luc, tac gia tien hdnh tinh todn. xac djnh cac thdng sd dau vao ciia bdi todn, ket qua tinh toan thu dugc nhu trong bang 1,
Bdng I. Cdc gid In thdng .sd ddu vdo chgy chuong trinh T T
1 2 3 4 5 6 7 8 9 10 I I 12
Thong so Ap suat khi quyen Ty trong cua dau cong tac Nhiet do dau cong tac He so gian no nhiet cua diu cong tac Chieu dai duimg ong hiit Chieu cao htit Duong kinh duimg ong hilt Gia tdc
Toe dQ quay ciia bam thiiy luc Dp nhcrt ciia dau a nhiet do He so ma sat dpc ducmg Hes6 Koriolis
Ky hieu Po P t
R
1.
K
i.
g ni, Uo J>
0 ,
Don vi Pa Kg/m'
"C
V
m m m m/s"
v/ph m"/s
Gia t r i 101325 854,5676 Thay doi 0.000875 l-^3 0.2-=-0.8 0.045-^0.06
9.81 Thay ddi 5.IO""((320*'C)
5,194 1.25
"^=^==^^ =1^
82 Tap chi KHOA HQC GIAO THONG V^N TAI So 50 - 02/2016
Sau khi chgy chuang trinh chiing ta thu dugc cac kit qua nhu sau;
EO.9
^ 0 5 SQA
• | 0 3 3^0,2
^ ,
"»*
^ ^ ^ ^
Chieu djii dirirno ong liQt, m D=004m — - -D^tMSm .. -0=005m [M)A55m< - • •D=006m
Hinh 6. Anh hudng cua duong kinh dng hiit vdi su thay ddi chieu ddi dng hut din hiiu sudt thi
tich cua bom thiiy luc
<^ •$> 'i' 4- <P Baimg kinh 6ng hCrt, m - L = 3 m L=2.5m
-L=1.5m — - -L=1ni
Hinb 7. Anh huong cua chiiu ddi dng hut vdi su thay dot dudng kinh dng hut din hiiu sudt thi lich
cua bom thuy luc
0 888
0 884
0 878
ziirr——
^
1 14172Q23 2629 32 3638414447 5053
~ Nhl$t dg eua diu c6ng (ac. t Setiesl _ . _ D = 0 06m
D = 0 045m
Hinh 8. Anh hudng cua dudng kinh dng hut din hiiu sudt hiit cua bom thuy luc
D = 0045m
Hinh 9 Anh hudng cua chiiu ddi dng hut din hieu sudt hiit ctia bam thuy luc Phdn tich kit qua tinh toan nhan dugc tren hinh 6 vd hinh 7, chiing ta nit ra mdt sd nhdn xet sau:
- Chieu ddi ciia dudng dng hut cd anh hudng den hieu suat the tich cua bam thiiy luc. Khi chilu dai dudng dng hiit tdng Ifin thi luu lugng lam vi^c cua bam thiiy luc va dp sudt lam viec giam, dan den lam gidm hieu sudt the tich ciia bam thuy luc.
- Khi dudng kinh dudng dng hut ndm trong khoang tir 0,045m din 0.055m thi hieu sudt the tich cua bam thiiy luc tdng; cdn d trong khoang tir 0.055m den 0.065m thi hieu sudt the tich ciia bcrm cd xu hudng gidm di, tuy nhien gid trj hieu sudt van d mirc cao r|q = 0,98 (vdi chieu ddi dng hilt la Im); khi dudng kinh 6ng hiit tiep tyc tang thi hieu sudt the tich ciia bam thiiy luc gidm rdt mgnh ri, = 0,48 (gidm 46,06%).
Phan tich ket qua tinh toan nhdn dugc tren hinh 8 va hinh 9, chiing ta riit ra nhan xet sau:
Dudng kinh vd chieu ddi cua dng hiit cdng ldn thi hieu sudt hut ciia bam thiiy luc sS gidm, hi^u sudt hdt ciia bom Ihiiy lyc la 0,845 ddi vdi dudng kinh dng hut 0,045m se giam xudng 0,67 vdi dudng kinh dng hiit 0,06m (giam 20,71%).
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T?p chi KHOA HQC GIAO THONG VAN TAI So 50 - 02/2016 83
