NGHIEN CLfU - T R A O D C I
v/XAY DLTNG DAC TJNH DAN H^l C O A L 6 XO KHI NEN
STUDY ON THE ELASTIC CHARACTERISTIC OF AIR SPRING ELEMENT ; |
TS. Nguyen Si Dinh, ThS. VU Manh Diing ; Hpc vien Ky thuit Quin sU
TOM TAT
Bii bdo xay dung md hinh vdt ly vi md hinh toin h,,c md ta 'tif tinh din hSi cua Id xo khi nen dua tren ly thuylt vl nhiet ddng lUc hoc Sau dd, md phong xiy dung dd thi bieu dien quan he gUadi Igld xlkhi nln vdi tan so Uch thich dao dgng hing phdn mim MATLAB - SimuUnk. Ket qua co tU tham khio cho viec nghien cUu cic he thing treo khi nen tren o to.
Tfl khoa: Bic tinh din hdi. Id xo khi nin, do cdng
ABSTRACT
In this paper, thephysical model and mathematical model that is described the elastic characteristic of air spring based on the thermodynamics theory is developed and presented. Then frequency depend^
stiffness characteristics graph of the air spring is simulated using MATLAB - Simulink software. Th result can be used as reference to the study of air suspension systems on automobiles.
Keywords: Elastic characteristics, air spring stiffness.
1. DAT VAN D E phuang phip dieu khiSn he thong treo.. .V6i sii phit trien cUa cong nghe nano, co khi chinh xic, Lo xo khi nen co nhieu Uu diem khi so viec sin xuit cic bo phin ket ciu phUc tap, vffl sinh V(Si cic loai phan tfl din hoi khac trong be yeu cau cao vi vat lieu cua 16 xo khi nen khdng thong treo tren 6 to (nhip la, 16 xo, thanh xoin, con li mot trd ngai Wn. Cung vdi xu hUdng viu cao su...) do li cho phep giim khoi luong chung cin thift nang cao do em diu chuyen ding khong treo, tUc giam tii trong dong tic dung cua 6 to, nen ngiy nay he thong treo v6i phaa ong dutog, tranh phi buy dUdng. Ngoii ra, 16 tU dan hoi la khi nen (16 xo khi nen) dang iiitjc xuoni
,.„ khi nen cho phep thay d6i do cUng va chieu phit tri& va Ung dung rong rii tren nhieu lo?l cao cua 16 xo ie phu hop vdi die dilm cua tii xe du lich. xe buyt vi thim chi ci xe co tai trpng trong tic dung, tin s6 kich thich mat dU6ng 16n. Do do, nghien citu ve he thong treo sfl dung bing cich diSu chinh lUflng khi nen trong 16 xo, 16 xo khi nen li m6t cong viec can thie't. Cie c6ng tao dieu kien thuin loi trong viec Ung dung cic trinh khoa hpc trpng vi ngoai nUdc di nghien
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NGHIEN CLfU-TRAO D 6 I
Cliu ve he thdng treo khi nen [1], cung nhU md phdng he thong treo bang may tinh [2]. Dac tinh dan hoi cua 16 xo khi nen cd diem dac biet la do Cling dong cd the dieu chinh thay doi gia tri cho phu hdp vdi tan s6 cua dao ddng kich thich [4].
Theo [3], do Cling cua 16 xo khi nen dUdc xac dinh bang thUc nghiem va sau dd diing phUcfng phap tuyen tinh hda de xay diing dac tinh dan hdi ciia he thong treo khi nen. Viec tien hanh thi nghiem d€ xac dinh tinh chat cua 16 xo khi nen phiic tap va tdn kem, dat ra y^u cau bdc thiet xac dinh mpt m o hinh phii hcfp ciia Id xo khi nen cho tiing bai toan khao sat dao dpng cu the cua dtd.
Bai bao trinh bay ccf sd xay dUng md hinh toan hpc cua Id xo khi nen cd the tich phu, xac dinh sU thay doi dp cdng cua 16 xo khi nen theo tan so kich thich dao dpng bang phUdng phap nhiet dpng. Ket qua nghien ciiu la cP sd tham khao de khao sat dao dpng cua d td cd sd dung h$ thdng treo khi nen, gdp phan hoan thien ket cau, nang cao do em diu va an toan chuyen dpng cua d td.
2. CG S6 LY THUYET X A Y D U ^ G DAC TiNH DAN H 6 I CUA LO XO KHI NEN
Khi xay dUng dac tinh dan hdi cua 16 xo khi nen can quan tam den qua trinh nhiet dpng lUc hpc ciia chat khi.
2.1. Qua trinh nhiet dong cua khi nen trong 16 xo Idii nen
Cac quy luat chung cua nhiet khi dong lUc hpc duac v i n dung vao ket cau 16 xo khi nen.
N^u coi buong khi la khdng gian kin va sU thay doi nhiet do la khdng dang ke thi quan he cua ap suSt v^ th^ tich l^:PoV"=p V"= const.
Trong do, p^ V^ la ap suat va the tich 6 trang thai tinh ban dau, ^ va V la ap suat va the tich d trang thai lam viec bat ki.
He sd dp Cling cua phan ttt dan hoi khi nen khac nhau vdi cac qua trinh nhiet ddng khac nhau: Dang nhiet, doan nhiet hay qua trinh da bien. Chi sd nen da bien (n) thay doi trong khoang l<n<Y tUPng iing vdi giCfa hai qua trinh dang nhiet va doan nhiet. Trong dd, y la chi sd nen doan nhiet (hang sd khdng thii nguyen). Dp Cling ciia phan td dan hdi khi nen cd gia tri nhd nhat, khi qua trinh nhiet ddng cua khi nen la qua trinh dang nhiet va ldn nhat khi do la qua trinh doan nhiet.
Khi Id xo khi nen bi nen cham, nhi^t dupc sinh ra rat nho nen co th^ xem la khong doi va qua trinh nhiet ddng do dUdc xem la qua trinh dang nhiet (vdi n - 1 ) . PhUPng trinh tinh toan cua qua trinh dang nhiet la: p V = const. The tich trong bieu thifc tren la the tich tong cdng cua phan tif dan hdi khi nen.
Trong qua trinh lam viec cua Id xo khi nen, rat it nhiet hi thoat ra mdi trUdng, ^d vay, nhiet do dUpc tang len khi 16 xo bi nen va giam di khi 16 xo bi gian. Qua trinh nay dUpc xem la qua trinh doan nhiet (vdi n = y). PhUPng trinh ciia qua trinh doan nhiet:
p^Vj ^p V^ =const
Tdm lai, tdc dp nen hoac gian cua chat khi se anh hUdng den bien dang cua phan td dan hdi khi nen. Tdc dp nen nhanh cho ket qua la qua trinh doan nhiet vdi ap suat va bien dang ldn hdn. NgUpc lai, qua trinh nhiet ddng la qua trinh dang nhiet vdi ap suat va bien dang be hdn.
Tren thUc te, qua trinh lam viec cua Id xo khi nen khdng phai la qua trinh dang nhiet, cung khdng phai la qua trinh doan nhiet ma la qua trinh da bien. Thdng thudng qua trinh nhiet dpng do dUdc xem la qua trinh doan nhiet hdn la qua trinh dang nhiet. Vdi gia tri cua y thudng dupc lay trong khoang tii 1,3 den 1,4. ^
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NGHIEN C l i u - T R A O D O I
2.2. Mo hinh 16 xo khi nen
Xiy dung mo hinh hpa 16 xo khi nen l i can thift trong mo phdng dpng lUc hgc cua he thong treo khi nen tren xe 5 to. Bai bao nay, trinh b i y nghien cflu 16 xo khi nen cua he thong nhu trong hinh 1, bao gom: Mpt bdng khi 3 (the tich chinh) dupc noi vdi binh tich nang 7 (the tich phu) bdi dudng ong dan 5. DUdi tic dpng cfla kich thich mat dudng, khi trong bdng khi se nen h o l e giin nd v i i p suit trd nen cin bing gifla t h i tich chinh va t h i tich phu. Cac thong so kich thude (chieu dii, dien tich...) cfla dudng ong d i n cd anh hudng den sU chenh lech ap suit gifla hai the tich tren. Do cflng phan tfl dan hoi phu thupc vao tong the tich cfla bong khi v i buih tich nang va duoc thay doi nhd van tai trpng 8. Cpng viec tinh t o i n l i phflc tap, cin dUa vao ly thuyet nhiet dpng cua chat khi. Cic thong sd quan trpng khi xem xft doi vdi chit khi bao gom: Ap suat, the tich, nhiet dp, khdi luong, khoi Iflong rieng v i trpng lupng cfla chat khi cung nhu hinh dang cua t h i tich binh chfla khi.
' 9 ) PO
•-MD
Tfl CO sd p h i n tich d tren, de xiy dUi^;.
md hinh nghiSn cflu cin mdt so gii thift: (i) MS; • hinh k h i o sit chi bao gom bdng khi va binh t i d ; ning duoc ndi vdi nhau bdi ong dan, pit tongf.
chiu tic dung cfla lUc theo phUdng t h i n g dflng (ii) Bd qua sU thay doi dien tich hi$u dung cfla, pit tdng; (iii) Bo qua dao ddng theo phUang.
ngang, (iv) Bo qua sU thay doi tinh chat, nhiit dp, hao but cua khi nen trong qua trinh khio sat, (v) Qua trinh nhilt dpng cfla khi nen trpng he thong la qua trinh da bien.
Tfl cic gii thiet d tren, phan tfl dan hii khi nen dUOc md hinh hda nhu hinh 2. Trong do, A v i V^ lin lUpt l i dien tich v i the tich hilu dung; p, l i i p suit khi nen trong bdng khi; p_ va V lan luot l i ap suit va the tich khi nen trong binh tich ning; A v i 1^ lin lUpt la dien tich mat cit ngang v i chieu dai dudng dng ndi 16 xo khi nen vdi binh tich nang; z l i bien dang cfla bong khi (sU dich chuyen cfla pit tong) theo phUOng thing dflng; Chuyin dpng cfla khi nen gifla hdng khi v i binh tich n i n g dupc d i e trUng bdi khii lupng m v i chuyen dich z^.
Md hmh toan hpc cua he dUpc xiy dUr^
bing each viet phuong trinh cin bing lUc tic dung len pit tdng (1) v i phuong trinh dpng lUc hpc cua kbpi khi nen di chuyen trpng dudng png (2).
Hinhl. Md hinh hi thdng treo si dung Id xo khi nen:
1) Satxi; 2) Gid dd; 3) Bdng khi; 4) Vau cao su:
5) Ong din; 6) Gic la; 7) Binh tieh nang:
8) Van tdi trong; 9) Binh khi nen; 10} Mdy nen khi
1 ^^
A, (Bong khi)
P,.V,
1^
»,
(Binh Tich nang) Pr.K
m^Jz^ =l.lxp. - A p , ) / i , -K^.z],
(1) (2)
Hinh 2. Mo hinh vdt If Id xo khi nen
Trong dd: F^ la tai trong tac dung len pit tdng theo phUdng thang ddng.
Gpi ap suSt ban dau trong phan td dan hoi khi nen la p^, bien dang z cua Id xo khi nen se gay ra sU thay ddi ap suat tUdng Ung A^^ va A^^
trong 16 xo khi nen va bmh tich nang. V^, V^ la the tich ban dau cua 16 xo khi nen va binh tich nang.
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NGHIEN CLfU-TRAO D 6 |
Ap dung ly thuyet khi ddng life hoc, xay dUng dUdc md hinh toan hpc cua phan tit dan hoi khi n e n (3) tUPng dng vdi md hinh phan tii dan hdi trong hinh 3.
\M^z^=C,(z-z^)-K^\i/sign (z^) '
Vdi F„^A,.p„-A,.p,,;
; C,
Trong dd: F^ la lUc tinh tac dung len pit tdng cua bdng khi; C^, C^ dac trUng cho do cdng cua khi nen trong bdng khi va trong binh tich nang; K la he sd can giam chan cua ddng khi trong dng din; |3 la he so phi tuyen giam chan cua khi nen; p la khdi lUdng rieng cua khi nen;
^ va M lan lUpt la he sd k^ den ton that nang lupng tdng cdng va khdi lUpng quy ddi cua khdi khi nen di chuyen trong dUdng dng.
J.
Kg M , //////>/////////y/y^//j^/////>///////
T
Hinh 3. Mo hinh phdn td dan hoi khi nen
Dp cUng dpng ciia phan td dan hdi khi nen se la tdng cdng cua ba thanh phan, bao gdm hai 16 xo vdi he so dp ciing C^ va C^ dac trUng cho dp Cling cua khi nen trong bong khi va trong banh tich nang, thanh phan thU ba la giam chan khi nen vdi he so can giam chan la K,.
(3) 3 . KET QUA VA N H A N XET
Giai he phUdng trinh (3) bang phUPng phap sd, ifng dung phan mem MATLAB - Simulink [2] di md phdng va xay diing dac tinh dan hdi cua phan td dan hdi khi nen. Sd lieu dau vao til he thdng treo khi nen cua xe Thaco Kinglong KB120SH. Ket qua khao sat la dd thi bi^u thi sU phu thupc cua dp cdng phan tii dan hdi khi nen vao tan sd kich thich dao ddng d td dUdc the hien tren hinh 4. Tren dd, ciing the hien sU so sanh giiia dp cUng dgng cua phan tif dan hdi khi nen va phan tU dan hdi kim loai.
D^C TINH TAN SO BI£N DO 0() CtJlSG »ONG
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400000 200DDD
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y 1
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Hinh 4. Dgc tinh tdn so bien do do cdng dong cua Id xo khinen
TU ket qua hinh 4, cd the nhan xet: Dp cdng cua phan td dan hdi bang kim loai xem nhu thay ddi tuyen tinh theo tan sd kich thich.
Do cdng 16 xo khi nen thay doi phi tuyen theo hudng tich cUc tUPng dng vdi cac tan sd kich thich khac nhau: Tai vi tri va trong khoang lan can viing cong hUdng t i n sd thSp (a) va cpng h u d n g tan sd cao (c), do cUng phan td dan h d i ' ^ ^
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II
NGHIEN ClJU - TRAO B 6 | ^ \
khi nen giim nham giam chuyin dich cua phan trep, tfl dd t i n g dd I m diu chuyen dpng; Cdii trong khoing lim viec (b) thi dp cflng tang len d i m bao cho chieu cao xe g i n nhu khdng thay doi theo tai trpng va dieu chinh dupc khpang sang gam xe.<'
Ngay n h i n bii: 24/4/2016 Ngiy p h i n biln: 16/5/2016
Tai lilu tham khao:
[1]. Trinh Van DUc (2014); Nghiin cdu dao ddng 6 td vdi hi thdng treo khi nen. Luin van Cao hoc, TrUdng Dai hoc Giao thong Van tai. , . . , , , , . . . .»-• j ' [2]. Nguyin Van Tri (2006); Nghiin cilu dng dung hi thdng treo bin tich ciic d sd dd 1/4 de nang cao do em diu chuyen ifonc cuo 0 (A Luan an Tien si. Hoc vien Ky thuit Quin sU.
[3]. M. Presthus (2002); Derivasion of air spring model parameters for train simulation. Master thesis, Lulea University of technology.
[4]. A. M. rpiiuiKeBiiq (1987), ABTOModraii KOHCTpyuuMji, KOHCTpynpoBamie paciei. CMCMCMH ynpaBaenua H xogOBaa lacTb, Bbiuiemiiaa uiKoaa, MPIHCK.
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