Tuyen tap bao cao khoa hgc Hgi nghi Khoa hgc ky thuat Do ludng toan qudc lan thur IV Hd Ndi, 11-2005
y DO RUNG VO XE VA TIENG ON BEN TRONG XE MINI BUYT 7 CHd NGOI SAN XUAT VA L A P RAP 6 VIET NAM
Du Qudc Think - DHBK Hd Ngi Li Trung Dung, Ddo Nggc Diep - Hgc viin KTQS
Tom tdt:
O td dang hogt ddng ludn phdt sinh cdc rung ddng vd tii'ng Sn. Do cdc qui dinh vi bdo ve mdi trudng cUng nhu cdc yiu cdu ngdy cdng cao cua khdch hdng, viic hgn chi tdl da mdc rung vd dn cua xe ludn Id muc tieu cda cdc nhd sdn xudt lap rdp d td. Bdi bdo trinh bdy qui trinh, ndi dung do nhdm xdc dinh mdc rung cdc tdm panel vo xe vd tii'ng on ben trong ca bin xe mini buyt 7 chd ngdi dugc lap rdp tgi Cdng ty d td Sdi Gdn. Ki't qud do Id ca sd cho cdng tdc nghiin cdu cdi tiin thiit kivd xe vd mdt sd'hi thd'ng khdc nham ddp dng cdc tieu chudn vi dn, rung.
I. T 6 N G QUAN
I. Rung dgng va tieng on cua d td
Khi xe d td dang chay se phat sinh ra r^t nhilu rung ddng va cac am thanh khac nhau.
Rung ddng cd thi nhan thay nhu ghi lac lam rung ngudi ngdi trfin nd, vO lang lac Ifin xudng lam tay ngudi lai bi rung, e^n sdhay chan ga rung mdt each khd chiu..., ngudi lai hay hanh khach cd thi cam thay khd chiu bdi nhflng rung ddng nay, phu thudc vao vi tn rung dOng va su rung ddng xay ra nhu thi nao.
Nlu am thanh do d t6 phat ra la khac thudng, qua to hoac khdng duge mong mudn thudng dugc ggi la tiing dn [2,4]. Nang lugng tifi'ng dn tfi xe mgt phin dfige toa ra mfii trfidng xung quanh nd, tifi'ng dn nay duge ggi la tiing dn ngoai (exterior noise); mOt phan duge truyin vao khdng gian bfin trong xe (nlu khOng gian nay dugc ddng kin hoan toan hoac mdt phan) va tifi'ng dn nay duge ggi la tiing dn trong (interior noise).
Tii'ng dn vd rung ddng Id hien tugng cd hihi cua xe d td lap ddng ca. Trong chuyin mdn, ngudi ta diing tieu chi NVH (Noise, Vibration and Harshness) de ddnh gid nhdng hien tugng dn, rung vd su va dap gdy nen cdm gidc khd chiu do d td tgo ra dd'i vdi con ngudi. NVH trong d td cd md'i lien he chdt che, nhdn qud vm nhau vd do nhiiu nguyen nhdn. Tiing dn chi la mgt phdn cua ndng lugng rung ddng ciia ki't cdu dugc truyin vdo trong khdng khi gdy ra su thay ddi dp sudt.
Trong nghiin ciiu NVH tren d td, 3 nhdn td sau ludn dugc chd y: Ngudn- nai tgo ra cdc kich thich ddng sinh ra rung, dn; Dudng truyin - ndng lugng rung dn dugc truyin nhu thi ndo; Cdm nhgn - rung, dn cd thi nhdn thdy, chiu dung nhu thi ndo.
Cdc ngudn chd yi'u gdy ra NVH d dto Id qud trinh ldm viec cua ddng ca vd hi thd'ng truyin luc, Id'p (su md't cdn bdng vd khdng trdn diu cua ldp, tucmg tdc gida ldp xe vdi mdt dudng), chuyin dich cda cdc tdm pa nen vd xe dudi tdc dung cua cdc logi tdi trgng; tuang tdc khi ddng cda gid vdi vd xe; kich thich cua map md mat dudng truyin qua hi thd'ng treo lin khung vd xe. Cdn dudng truyin cua rung ddng trin d td bao gid cdng qua thdn vd xe, trudc khi caquan thinh gidc vd xuc gidc cua con ngUdi cdm nhgn dugc [2].
Tii'ng on ngodi gdy dnh hudng xdu din mdi trudng xung quanh vi nd tdc ddng true tie'p di'n mdi Irudng sdng. Id mdt trong nhdng nguyin nhdn gdy d nhiim mdi trudng. Id nguyin nhdn chu yi'u cua mdc dn todn bii trong thdnh phdvd cdc vdng lan can, ddc biit d nhdng thdnh phd Idn khi giao thdng van tdi dudng bd phdt Irien mgnh.
Tifing fln trong gay khfl chiu, met moi, tao cam gidc kem thoai mdi cho hdnh khdch va la mgt trong nhflng nguyfln nhan gidn tifip gdy mdt an todn chuyfin dgng dfii vfli ldi xe.
Vi vay, ban che tfli da tifing fin (ca ngoai va ttong) cua fl tfl la vdn dfi cdp thifit ttt quan difim phdp ly cung nhtt quan diem thucmg mai.
2. Do rung, on va tieu chuin danh gia
Xudt phat ttt nhttng yeu cdu neu tren, viec do mtte rang va fin cia fl tfl, dac biet la cac loai xe con, xe chfl khach da dugc tat ca cdc nhd san xudt fl tfl quan tdm. Mic rang, fin cho phep cia fi tfi ciing dttgc hdu hfit cdc hang san xudt, cdc qufic gia thuc hifin bang cdc tifiu chudn nhdm bdo vfi mfli traflng. Mflt sfi tieu chudn cdc nuflc trong Hnh vuc nay cfl thfi thdy nhtt rOCr 7495-63 cua Lifin Xfl (cu) qui dinh tifing fln ben ttong xe buyt; SAE J986 (cia Hfli ky su fl tfi My) qui dinh mtte fln bfin ngoai xe chfl khdch... Dfi danh gid theo cdc tieu chudn, cdn phai tifin hanh cdc phfip do.
Dfi do rang cdc kfit cdu fi tfi, ngufli ta thuong si dung phuong phap do gidn tiep vfli cac cam bifin gia tfl'c kieu dp difin gdn true tifip len ngufln rang. Day Id phuang phdp phfi bie'n nhdt bifin nay, dugc cdc hang chuyen cung cdp thifit hi do nhtt B&K (Dan Mach), QUEST (My), RION (Nhat), STEYR (Ao)... ttng dung. Ngoai ra, hien nay do rang kfit cdu fi tfi cfin dugc kfit hgp vfii ky thudt do bdng chup anh giao thoa laser (holographic) nhu hang LMS cua Bi dd trifin khai. Dfi la ky thudt phat vd thu phan xa cia tia laser t i b^ mat mng cia kfit cdu, he thfi'ng do khfing tifip xuc true tifi'p vfli ngufin rang.
Dfi ddnh gid mtte fin tfing thfi bfin ngodi cia fl tfl, cdc cam bifin do am thttflng dttgc dat cdch true dgc cia xe theo dttflng chay fl khoang each 7,5 m va cao 1,2 m so vfli mat dttflng. Dfi do tie'ng fin bfin ttong vo xe 6 tfi, ngttfli ta dat micrfi tai nhirng difim ndm tren dttflng true cia xe fl dfl cao 0,7 m tinh t i difim gitta ghfi ngfii. Dfl'i vfli nhflng fl tfl bu^t cfl tren 6 hang ghfi va cfl cabin tdch bifit thi viec do tifing fln dttgc thttc hifin bfin tren hang ghfi thtt nhdt, bfin tten hang ghfi cufii cung va fl gitta cac hang ghfi dfi. Trong cabin ngttfli ta do mtte tifing fin phia trfin ghfi ngfii cia ngttfli lai xe [3].
Vi nhifiu ly do is nttflc ta chua cfl nhifiu cdc tifiu chudn ddnh gia rung, fin dfli vfli fi tfi.
Hifin mfli chi cfi tifiu chudn qui dinh phttong phdp do vd gifli ban cho phfip cia cac mic fln ngodi dfli vfli phttong tifin giao thflng duflng bfl trong cflng tdc ddng kifim. So sdnh vfii tifiu chudn cia mflt sfl nttflc khdc, thi tieu chudn cho phep cua Viet Nam co mtte "ttdn" cao hon, chang ban cing fl khoang cdch 7,5 m, TCVN 6436: 1998 cfl gia tti mtte fin tfii da cho phep cia fi tfi con, 6 tfi tdi, 6 tfi chuyfin ding va 6 tfi khdch hang nhe Id 103 dB(A), ttong khi dfi theo tifiu chudn qufl'c tfi (ISO), ta thdng 4 - 1970 mtte tifing fin bfin ngoai cia xe fi tfi buyt chay nfli, ngoai thanh khfing dttgc vugt qud 89 dB(A).
Mfit stf cac bao cdo nghifin cttu gdn ddy cia cdc tdc gia ttong nttfic [5] cung chi nghien cttu khao sat cdc vdn dfi tifing fin giao thfing do fi tfl phdt ra bfin ngodi mfii traflng cing cac anh httflng cua nfi. Chtta cfi tdi lieu nao dfi cap dfin tifing fin bfin ttong, kfi ca tifiu chudn tifing fin ttong cia cdc xe chfl khach.
3. Nfli dung nghien cliru, muc dich cua thi nghiem
Ndm ttong khufln khfl du an KC.05.DA.I3, nhom nghien cttu tifin hanh ddnh gia mtte rang cia vo xe va tifi'ng fin bfin ttong ca bin xe mi ni buyt 7 chfi fl difiu kien boat dfing binh thttflng. Muc di'ch cua thi nghifim nhdm tim ra cdc ving tdn so xdy ra cflng huflng dao dflng cia vo xe trong dai tfi'c dfi si dung; xac djnh bifin dfi (dich chuyfin, gia tflc) dao dfing
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cua vd xe; xac dinh eac mfic tiing dn trong ca bin, so sanh cac mfic dn thuc t l vdi mfie dn cho phdp theo qui dinh. Cac kit qua thu dugc lam co sd dl danh gia hifiu qua cua cac bifin phdp dugc dl xuat nham giam mfic dn trong d td.
II. QUI TRINH, NOI DUNG THI NGHIEM 2.1. ChuSn bi thf nghifim
2.1.1. Phfiong phap do
- Sfi dung phuong phap do gia tdc rung eua cae t ^ panel efing vdi eac cam bie'n va thilt bi do chuyfin dung cd kha nang ghi, phan tich dl xay dung dac tinh bien dd tSn sd.
- Xfi ly sd lifiu do bang cac phan mem chuyen dung va toan hgc nham dat duge cae thOng sd theo yfiu ciu.
- Six dung phuong phap do kilm tra dl do mfic dn trong ca bin (theo TCVN 5136-90).
2.1.2. Ddi tugng (xe) thf nghifim
Bang 1: Cac thong sd ca ban cua xe thf nghiem Dac tinh ky
thuat - Chilu dai - Chilu rfing - Chilu cao Kiiu ddng cd Sd ch6 ngdi (kl ca ngudi lai) Dung tich xi lanh Khdi lugng xe
Don vi tfnh mm mm mm
Thong sd 3745 1505 1925 Xang, 4 xi lanh.
Ngudi cc Kg
8 1051 1050
Dac tfnh ky thuat Khoang cdch true vet banh truOc vet banh sau COng suit cue dai MO men xoan cue dai Ceidp van tdc cue dai
Don vi tfnh mm mm mm Kw/vq Nm/vq
Thdng s6 2370 1300 1310 38.5/5200
83/3500 155 R 13 Km/h 1 n o Xe thi nghiem Id xe mini buyt loai 7 chfl ngfii dugc san xudt, Idp rdp tai nhd may fl tfl Sdi Gfln (SAGACO), san phdm cia Du an khoa hgc cflng nghfi cdp Nhd nttflc KC.05.DA.13
"Hodn thien ddy chuyen san xua't, Idp rap 6 to mini buyt 6 - 8 chfl ngoi mang thuong hifiu Vifit Nam". Cdc thflng stf ky thuat co ban cia xe dugc mfi ta ttong Bang 1 fl trfin.
2.1.3. Chudn bi ky tiiuat xe thi nghiem
Traflc khi thi nghiem, xe dugc kifim tra, difiu chinh todn bfl tinh trang ky thuat theo tieu chudn dang kifim Viet Nam. C!dc nfli dung chudn hi xe thi nghiem dugc thttc hien tai nhd mdy fl tfi Mfi Kfing Cfl Loa gfim: 1-Ria xe; 2-Kifim tra dflng bfl cua xe; 3-Kifim tta lam viec cia dfing eg vd HTTL; 4-Bom va kifim tta dp sudt lflp; 5-Kifim tra van tfic vd cdc chi stf cia dfing hfi tfi'c dfi; 6-Kifim tta difiu chinh he thfing phanh; 7-Kifim tta difiu chinh hfi thfing ldi; 8-Kifim tra nfing dfl khi xa; 9-Kifim tta he thfing den chieu sdng, cfli, den tin hifiu; 10- Kifim tta stt cfi dinh chdc chdn cdc canh cia, giodng kinh.
2.1.4. Thie't bj, vdt ttt cho thi nghifim
a. Hfi thong kiem chain d£u do rung Bruel&Kjaer: Cfl tdc dung hifiu chudn lai thifit bj do theo difiu kifin hifin traflng, ttanh sai stf.
b. He tho'ng do rung va on B&K: Type PiniSE 3560 cing phdn mfim Pulse LabShop V.4.I.
Hinh 1: He thong B&K type PULSE 3560 + S«hieumay: 2085721
+ S6 kenh do: S + Dai tfin phan tich: 0.01 - 100 kHz + PhSn mSm Pulse LabShop v.4.1 thiSt lap chf 66.
luu tri} sfi lieu do.
Hinh 2: Cam bie'n do rung dugc gdn tren tam vo xe
c. Sensor B&K
Hlnh 3: B&K gia toe:
Type 5958.
+ D6 nhay: ImV/ms-.
+ DJi tSn hoat d6ng:
1 Hz - 14 kHz.
Hinh 4: B&K gia tfi'c:
Type 8325 + D6 nhay: 10 mV/ms'^
+ Dai tSn boat dOng: 1 Hz - 10 kHz.
Hinh 5: Sensor do am:
B&K type 4188 1-DO nhay: 31.6 mV/Pa + Dai tSn hoat d6ng:
8 H z - 12,5 kHz.
2.1.5. Dia difim, thfli gian, difiu kifin thi nghiem a. Dia difim
Chudn bi ky thuat xe: Do tten ralfl va do uen cdu nang dugc thuc Men tai Nhd mdy fl tfi Cfi Loa - Cfing ty fi tfi Mfi Kfing, Dfing Anh - Ha Nfli.
Do khi chay xe ttfin duflng dugc thuc hien trfin qufic 16 18 (doan Nfii Bai - Bdc Ninh), do doan duflng nay cfi chdt Iugng tfit, cdch xa khu dan ctt, mat dfl xe thdp nfin tifing fin ngodi it anh huflng toi kfi't qua do.
b. Thfli gian: Ngdy 15 va 16 thdng 4 nam 2005.
c. Dieu kien thi nghiem
Dfii voi xe: Xe thi nghifim mfii chay dfin 2100 km; da dttgc kifim tra chudn bi ky thuat nhu trinh bdy fl phdn ttfin; tai ttgng xe khi thi nghiem: 4 ngttoi/7 ngufli; xe dugc dflng kin cdc c i a kinh; hfi thfing difiu hod nhifit dfi ddt fl chfi dfl lam vific trang binh.
Dfii voi noi t h i nghifim:
- Do ttong nha may Me Kflng khi toan bfl nha may khfing lam vific (ngay nghi).
- Do uen duflng ttong difiu kien thfli tifit tfit, dam bao cdc yfiu cdu vfi difiu kifin do dugc qui dinh trong TCVN 5136-90: khfing mtta, khfing cfl gifi manh, duflng khfi rdo, nhiet dfi ngodi tiin ttung binh 27°C.
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2.2. So do lap d$t thi nghiem tren d to Kv hifiu
- SS 1: Sensor do gia tdc gdn trfin tSin san.
- SS 2: Sensor do gia tde gin tren tSin trudc.
- SS 3: Sensor do gia tdc gan trfin t^m ndc.
- SS 4: Sensor do gia tdc gSn trfin tam sau.
- SS 5: Sensor do gia tdc gin trfin tflin phai.
- SS 6: Sensor do gia tdc gin trfin ta'm trdi.
- SS 7: Sensor do am trong cabin tai vi tri ddu ngudi lai, each mat ghfi'ngdi 0.7 m.
Hinh 6: So do bd trf c^c diem do 2.3. Ngi dung va cac birdc thurc hien thf nghiem
2.3.1. N6i dung
Nham tao ra nhfing tinh hudng kfch thich khac nhau lam rung kit cau vd xe, ndi dung do bao gdm 3 bai thi nghifim tai 3 vj tri do: Trfin rul6, trfin ciu nang va trfin dudng.
- Do trfin ruld va cSu nang cd thi loai bd anh hudng khf dOng cua gid.
- Do trfin ruld dl ban cbl anh hfidng cua m^p md mat dudng.
- Do trfin cau nang dl loai bd hoan toan tuong tac cua Idp xe vdi mat dudng; ed thi tang tdc ma khOng eSn ddi tay sd.
- Do trfin dudng nhu trong diiu kifin hoat d6ng binh thudng cua d td.
Trong mdi bai thi nghifim, tiln hanh do d cac tdc dO dn dinh (30, 40, 50, 60, 70, 80 km/h) va tang tdc (0 din 45 km/h; tfi 40 dfi'n 80 km/h) dl tfi dd rut ra cae so sdnh, ddnh gia kfi't qua gifia cdc chi dd.
2.3.2. cac budc thuc hifin
1- Lap dat thifi't bi do theo so dd. Cae cam biln do rung dugc dat trfin cdc tam panel chinh cua cac mang vd xe, hudng do trting vdi phuong phap tuyin cua cde tam; cam biln do am dugc dat lai cac vi tri tai ngudi lai xe va d gifla mdi bang ghi hanh khach, each mat ghi 0,7m
2- Dfia xe vao vi tri do (theo bai thi nghifim: trfin rulo, cau nang hoac ngoai dudng).
3- Do, ghi tie'ng dn nin.
4- Dua xe den ehl dd lam vific da dinh (tang tdc hoac gifi d cac tde dd 6n dinh).
5- Tiln hanh ddng thdi do rung, dn 6 cac ehl d6 da dinh (theo vi tri do, tdc dd). 6 mdi cbl dg tiln hanh do 5 iSn dl lay kit qua trung binh. Ghi lai dfl lifiu.
6- Xfi ly, phan ti'ch, ti'nh todn ede sd lifiu do.
III. KET QUA THI NGHigM 3.1. Xfi ly kit qua do
Sd lieu thu dugc khi thfi nghifim la gia tdc (m/s^ - khi do rung) va dp am (Pa - khi do dn). Day la cdc tin hifiu hinh sin theo thdi gian, vdi cdc tan sd khdc nhau. Di nhan dugc cac dfi lifiu trong vung tan sd, cdn xfi ly kit qua do bang viec phan tfch tan sd, tfic la vdi cac dilm dfi lifiu theo thdi gian, dung phep biln ddi Fourier nhanh vdi cdng cu ph&i mim DasyLabT.
Xfi ly sd lieu do bang p h ^ mim DasyLap7 nhd cdc mO dun: Dgc sd lifiu - Hiin thi phd tfn hifiu theo thdi gian - Phdn tfch FFT - Ghi ra file kit qua.
3.2. Tinh toan cac dai lugng theo yeu cdu
Yeu cdu kfit qua thi nghiem la dac tinh tdn sfi - bien dfl dich chuyfin (tinh bdng mm) vd tdn stf - mic dp sudt dm (tinh bang dB), do vdy cdn tinh todn x i ly dfi nhdn dugc dang kfit qua mong mufi'n.
3.2.1. Tinh todn cdc dai lugng rang
Cdc gid tri vdn tfic, dich chuyfin cia rang dfing nhdn dugc bdng cdch tich phdn phfi quan he tdn stf - gia ttfc rang da nhdn dugc, nhfl thifit lap cac mfl dun tich phan tuong ttng trong DasyLab.
3.2.2. Tinh todn cdc dai Ittgng tifing fin (theo TCVN 5136-90) a. Mic ap sua't am: L = 20.log—
in
L : Mtte ap sudt am (dB) P : Ap sudt am do dttgc (Pa).
P„: Ap sud't chudn; P„ = 20.10'' (Pa)
b. Mic am (mic ap sua't dm co trgng so): L,, = lO.lgJjlO MC,-I:AI) (1)
(2) LA : Mtte am, [dB(A)]; L,: Mtte dp sudt am trong dai tdn sfi thtt i, [dB].
Kji: Dac tinh trgng stf tdn stf theo trgng sfi A; ttng vfli tdn stf danh dinh (tdn sfi trung binh nhdn) cia dai tdn thi i, [dB].
n : Sfl Ittgng cdc dai tdn sfi.
c. Mtte dm tugng dugng
Tifing fin ttong fi tfi la tifing fin bifi'n dfii (hinh 8). Dfi danh gid, so sdnh anh httflng cia cdc dang tifing fln bifin dfii, ngttfli ta thttflng tinh tifing fin tucfng dttcmg. Vfli mfit dang tifing fln bifin dfii cho traflc, mtte am tttong dttong cia nfl Id mtte dm cia tifing fin khfing dfli, dai tdn rfing, khfing phai xung, gay tac dfing len con ngttfli gifing nhu tifi'ng fln bifin dfli dfl.
Cdch tinh mtte am tttong dttcmg theo httdtig ddn cia cdc tdi lifiu tham khao [6].
3.3. Kfi't qua thi nghiem
3.3.1. Kfit qua rang cua cdc tdm panel vo xe
Hinh 7 thfi hien phfl kfit qua do rang cia tdm sdn khi chay xe tten dttflng fl tfic dfi 60 km/h.
1
,0.8 0 7
f l '
0 3 0.2
0 0 E E
L
AlC<Road, V-60, Floor
LJAju-Jjlk. .-.."•.
50 100 150 200 : I 350 400 460 500 550 i
Hinh 7: Pho rung ciia tam san khi chay xe
tr£n dirdng d tdc do 60 km/h Hlnh 8: Phd ap sua't am tai dSu lai xe khi chay xe trfin dudng d tdc d6 60 km/h
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3.3.2. Ke't qua mfic 6n (tai vi tri ddu ngudi lai xe)
Tfi kit qua do ap sua't am, theo edng thfic (1) cd thi xac dinh dang phd tiing dn tai mdi ehl dO do nhu dfige thi hifin d hinh 8.
Hinh 9: Mfic am trong cac dai dc ta d 60 km/h
Hinh 10: Mfic ap sua't am trong cac dai dc ta d 60 km/h
a. Mfic ap sua't am cd trgng sd (mfic am)
Mfie am LA (dBA) trong cdc dai dc ta vdi cac tdn sd trung binh nhan tfi 12.5 din 1000 Hz duge xde dinh theo cdng thfic (2). Hinh 9 bieu diln mfic dm d tdc dd 60 km/h khi chay xe trfin dfidng.
b. Mfie dp suat am
Mfic dp sud't am trong mdi dai dc la cd tdn sd trung binh nhan tfi 12.5 dfi'n 1000 Hz.
Hinh 10 la mfic dp sudt am d tdc dd 60 km/h khi chay xe trfin dudng.
c. Mfic dm tuong duong
Bang 2: Mfic am tuong duong Mtte dm tuong duong dB(A) 30
km/h 40 km/h
50 km/h
60 km/h
70 km/h
80 km/h
0-45 km/h
40-80 km/h Khi chay xe tren duimg
68 72 71 1 76 1 76 j 72 71 75 Khi chay xe tren cau ndng
67 69 75 1 74 1 67 1 67 64 67 Khi chay xe tren rulo
64 70 70 1 64 1 65 1 64 70 78
IV. BAN LUAN VE KET QUA THf NGHIEM
Kfit qua do rang, fin va x i ly tinh todn fl tdt ca cdc chfi dfl thi da nfli fl trfin cho thdy:
- Ddc tinh bien dfl tdn sfi cia vo xe cfi cdc gid tri bifin dfl cdn quan tam ndm ttong ving tdn sfl thd'p, khoang dttfli 400 Hz. Ngodi khoang tdn stf ndy, bifin dfl dao dfing rdt be.
- Trong khoang tdn sfi dfin 400 Hz, vo xe cfl ttt 6 dfi'n 8 difi'm xdy ra cfing httflng xung quanh cdc tdn sfi 20, 50,76, 105, 145,170,235 Hz.
- Trong toan bfl dai ttfc dfl thi nghifim cua xe t i 30 dfin 80 km/h, 6 cdc tfic dfl 50, 60 knVh bien dfl dao dfing cfl gid tri Ifln nhdt.
- Mtte fin trong ca bit tai vi tti ddu ngufli Idi xe dat gid tti cao nha't fl ving ttfc dfi lan can 60 km/h (Bang 2: mic dm mong duong dat 76 dB(A)). O cdc tfi'c dfl thdp bode cao hom thi tifing fln cung giam. Khi fl tfl tang ttfc thi tifing fin cung tang lfin.
- Do chua cfl tieu chudn rieng dfi ddnh gid, nhflm nghifin cttu so sanh kfit qua vfli cdc tifiu chudn khdc: Nfiu so vfli rOCT 7495-63 cho phep xe ttfildybuyt khi chay ttfin duflng nhua ttfc dfl 45-50 km/h mtte fln khflng dttgc vttgt qud 70 dB(A) thi mtte fln cia xe do cao hon 1-2 dB(A). Nfiu so vfli TCVN 3985-1999 qui dinh mic tifing fln cho phfip tai cdc vi tii ldm vific dfli vfli mtte dm urong duong Id 85 dB(A) thi tifi'ng fin trong xe da do la 76 dB(A), thdp hon 9 dB(A). Cung theo tifiu chudn nay, mtte dp sudt dm fl cdc dai tfc ta cua xe dugc do cung thdp hon gid tri cho phep, chdng ban fl tdn so 1000 Hz Id 32 dB so vfli cho phep la 75 dB.
V. Ldl C A M O N
Chung tfli xin bay to Ifli cam on chan thdnh dfi'n ban lanh dao va cdc cdn bfi, nhdn vifin cia cdc co quan: Trang tam PTCN 6 tfi, Du dn KC.05.DA.I3, Phfing Thi nghiem Dfing Ittc hgc - Vifin Cg hgc, Chi nhdnh nhd may ft tfi Mfi Kfing Cfi Loa, Bfi mfin Xe QS - HVKTQS da hfit sttc tao difiu kien, giup dfl chung tfli thuc hifin thi nghifim ndy.
Tdi liiu tham khdo:
[1] Bruel & Kjaer. Structural Testing (Part 1 & 2) Revision April 1998, DK 2850 Naerum, Denmark.
[2] Toyota Service Training. NVH (Noise - Vibration - Harshness).
[3] Cryil M. Harris, PhD, Handbook of Noise Control. McGrcm-Hlll Book Company, Inc 1957.
[4] Karl D. Kryter. The Effects of Noise on Man. Academic Press, Inc 1985.
[5] Bid Vdn Ga. Tie'ng dn do d td gdy ra. Tap chi Thdng lin Mdi trudng QN-DN, sd 211997.
[6] TCVN 5136-90: TCVN 6398-7:1999: TCVN 6775:2000.
