Cơ sở khoa học của việc lắp đặt bộ điều hòa lực phanh trên ôtô vận tải

NGHIEN cuu-TRAO 001 Cd s o KHOA HOC CUA VIEC LAP DAT BO DIEU HOA Ll/C PHANH TREN TO VAN TAI SCIENTIFIC BASIS OF INSTALLATION OF REGULATE BRAKE PRESSURE ON TRUCK GS.TS Vu Diic Lap', Dumg Van Toan^ 'Hoc vien ICy thuat Quan sir ^Truong Cao dSng Kinh tS - Ky thuat Vinh Phiic TOM T A T Trong nhirng nam gdn day, td van tdi ddng vai trd rdt quan trong suphdt trien ctia nen ki te nu&c ta Viec sir dung to van tdi dd ddn tra thdnh tdt yeu vd mite su dung mot gia tdng T den thdng 572011, sdn luang lap rap vd nhgp khdu d td cd su tdng trudng tir 6% -10% Vay viec nghien ciru, lap dat thiet bi dieu hod lucphanh tren xe to van tdi Id rdt thiet thuc vd cdp gdp phdn ndng cao chat luangphanh td vd gdp phdn gidm thieu tai nan giao thdng a Viet Nam hien n Tir Ichoa: Dieu hod lire phanh; Ca s& khoa hoc; O td van tdi, hieu qud phanh ABSTRACT In recent years, truck plays a very important role in the economic development of our country Using trucks has gradually become inevitable and the level of usage is increasing more Up to May 2011, the automobile assembly production and the automobile import grow from 6% to 10% So the study and the installation of regulate brake pressure on truck are very practical and urgent, and contribute to improving the quality brake and reducing traffic accidents in Vietnam today Keywords: Regulate brake pressure; Scientific basis; Trucks, brake effectiveness I DAT VAN DE Cac doanh nghiep san xu4t lip rap to tren Hien nay, nhn cong nghiep to cua Viet Nam CO ban g6m phSn: Ph^n Co to Hoa Binh; Cong ty to 1-5, Cac cong ty to hen doanh: Toyota Viet Nam; Ford Viet Nam; Vidamco; Nissan; Honda co so cac cong ty co qu6c doanh: Cong ty C6 " "S ty O to 3-2 Cac doanh nghiep tu nhan: Doanh nghiep Tu ' TAP CHi CO KHl VIET NAM, S6 nam 2014 www.cokhivietnam.vn NGHIEN CUV-TRAODOI nhan Vinaxuki; Cong ty to Truong Hai; Cong ty to Chien Thang Theo danh gia cua eac chuyen gia, nganh cong nghiep to co toe tang truang manh me nhung quy mo khiem ton Trong cao an toan chuyin dgng (han che trugt ngang cau xe) Bg diSu hoa luc phanh la mgt cac ket c4u bd tri tren xe nh5m thuc hien muc dich Trong ngi dung bai nay, chung toi ehi de ca,p tai bg dilu hoa lure (BDH) phanh hai thong so b6i canh thi truang to the giai rai vao khung -uy hoang, san lugng to tieu thu giam siit manh nhung nganh to Viet Nam dugc danh gia da vugt qua thai ky khiing hoang va co su phat BDH triln kha 6n dinh Tinh den thang 5/2013, san (C, C2, D, d } lugng lap rap va nhap khau to co sir tang truang tir 6% - 10% D8 giam thieu tai nan giao thong a Viet Nam, ngoai viec hoan thien tang giao thong, viec nghien cuu hoan thien ket can cae to lap rap Hinh 2.1: Sa dd cdu true hi thdng diiu chinh luc phanh BDH hai thdng sd: nuac dat cho cac nha khoa hgc can phai nghien cuu nang cao chat lugng to noi chung va chat lugng phanh noi rieng Vay, viec nghien cuu, lap dat thiet bi dieu hoa lue phanh tren xe to van tai la rat thiet thuc va cap bach, gop phan nang cao chat luong phanh to va gop phan giam thieu tai nan giao thong a Viet Nam hien T: Hi thdng treo; A: O td; TP: Tdng phanh Nhin vao sa cau true tren hinh 2.1, ta thay BDH luc phanh khong chi dugc dieu khien bai ap suat p^ tu tong phanh ma no dugc dieu khien theo tai trgng F^ Trong qua trinh phanh, tai trpng tren eau sau thay doi dan den lue tac dgng len piston BDH lam thay doi ap suat rap^ phu hgp vcri sir thay doi tai trpng tren eau sau phanh KHAO SAT DAC TINH LAM VIEC CIIA BQ BIEU HOA LlTC PHANH HAI THONG SO Nhu chiing ta da biet, cac qua trinh phanh to deu dan tai hien tugng tang tai trgng tae dung len can truac, giam tai trgng a cau sau Su phan bo lire phanh can thiet phai dam bao mdi quan he giija mo men phanh sinh a chu phanh (hay lue phanh sinh a banh xe) ty le vai phan luc thSng dung tac dung len cae banh xe Thuc hien dugc yen cau se nang cao chat lugng phanh, giam mai mon lop, tang kha nang dieu khiin xe va nang Hinh 2.2: Ket cdu vd sa nguyin ly ciia BDH luc phanh hai thdng sd Tren hinh 2.2 the hien cu thi vl kit ciu va sa d6 nguyen ly lam viec eua BDH luc phanh hai thong s6, gom mgt so chi tiet ca ban nhu sau: 1) g TAP CHi CO KHi VIET NAM, S6 nam 2014 www.cokhivietnam.vn NGHIEN ciru-TRAO DOI Piston; 2) Vach ngan; 3) Vanh ty; 4) Xilanh; 16 xo /,„: Do bien d 1; 16 xo va cac chi tilt khac Khi tiep tuc dap phanh, ap suat p tang tai gia Khi chua phanh, 16 xo va ca cau dan dgng I ban dau cua 16 xo tri p^, piston BDH tiep tuc dich chuyen sang trai n6i chu sau vai BDH dky piston sang ben phai ty eho tai vai ciia piston cham vao vach ngan sat vao v6 cua bg Dieu hoa Liie nay, du6Tig dau khe ho S = 0, ngan each khoang A vai khoang thong til tong phanh xilanh phanh banh sau, ap B Liic nay, khoang B tra khoang kin: Tir suat dau dan dgng phanh: Pj=p^= van dieu chinh ap suat tai xilanh phanh banh sau p^^ Khi ap suat khoang A bang ap suat Khi phanh, ta xet giai doan: khoang B va bang ap suat lam viec p^ cua BDH: + Giai doan T Ap suat dau dan dgng Pl^P2=Po tang tir/7=;7^ d i n ;;„ + Giai dogn 2: Giai doan lam viec cua BDH, Do ket cau cua BDH luc phanh co khe ap suat dau din dgng tiep tue tang (p^ > p^ nen khoang A thong vol khoang B, ap suat dau - Khi ap suat/?, tiep tuc tang, piston ciia BDH dan d6ng toi xi lanh phanh truoc va xilanh bi day dich sang trai, tach vach ngan khoi vanh phanh sau la bang nhau^^ = p^ ^ p Khi ap suat ty Phuang trinh can bang lire doi vai piston a p tang den mgt gia tri p ' nao do, vai p ' < p^ cong trang thai la: voi sir chenh lech dien tich cac bac cua piston thi piston se bi dich chuyen sang trai mgt khoang / so voi vi tri ban dau, dong thai co su giam tai trgng cua ciu sau phanh lam cho piston cua Trong do: F\: F'^=C/l^ BDH dich sang trai them mgt khoang / \ Khi phuong trinh can bang lire doi voi piston a trang thai can bang la: Fx=P la luc nen ciia ea eau din dgng BDH a vi tri mai + l'-l"J (2.5) T: La khoang dich chuyen ciia piston a trang thai mai; 7rd^ — + F^2(2.1) l"^ La khoang dich chuyen cua piston su giam tai gay a trang thai mai; Trong do: F^ La luc nen cua ca ciu din dpng BBH a vi tri dang phanh: F^=C^.(l, F^^i La luc nen ciia 16 xo 1: ^,„ = C//,„ + / - - < - / V + l-rj(2.2) (2.6) l^g: La bien dang ban dau ciia 16 xo 1; Cy, Do Cling cua co ciu din dong BDH; F'j^^: La luc nen cua 16 xo ; : Dp biSn dang ban d i u cua 16 xo co cau din P'i.2 = Cfi„^r-l"J dpng; F,^^: Luc d l y cua 16 xo (ngupc chi6u vdi (2.7) Quan he ap suat xi lanh banh xe ciu tnrac vdi xi lanh banh xe cau sau qua trinh phanh: fia = C/l,,-l-rj(2.3) C : Do cung 16 xo 2; 4 -' Tir cong thiic (2.4) d i n (2.8) ta xac dinh dugc ^ TAP CHi CO KHi VIET NAM, S6 nam 2014 www.cokhivietnam.vn NGHIEN ciiu-TRAO001 phuang trinh dac tinh lam viec ciia BDH hai thong so: * Xac dinh khoang dich chuygn /' va /« ciia piston - Tinh / "^: Khi phanh co su giam tai a ck sau lam thay doi khoang each / giiia san xe va p,-A.p, + B.[F\+F^^-F\Jkhip>p^ v6 chu Su thay d6i thong qua bg phiin dau Trong do: ^, B: La cac he so ket cau ciia BDH: h6i ciia BDH (16 xo ca c4u din dgng) lam piston BDH dich chuyen mgt khoang r\ ^ i^j-f dayi^ Dt'Dt B = la he s6 dku dgng cua 16 xo din dgng BDH KiDl-D;) Dl-Dt ' Pi^Pi ^^^Pi^Po C^: La cung ciia ca cau dan dgng BDH; C,, C, - la Cling ciia 16 xo 1,16 xo ciia BDH; D , D^- la duong kinh xi lanh, piston eua BDH; d: La du6ng kinh than piston BDH Khoang cach/dugc xac dinh theo cong thiic: _G.a-g,.L PA L.C,., (2.9) L.C., Ci day: g^ Trpng luang phSn khong dupe treo; C ,: Do Cling tong cong he thong treo cau sau; P: Luc quan tinh cua xe phanh ./• = Gia toe cham dan j cua xe phanh dat duoc gia tri lan nhat la liic sii dung luc bam Ion nhat: -(p.g = (p.a = P G.a-g^.L ip.GJi^ (2.10) P,„x P, Hinh 2.3: Dd thi dgc tinh Idm viec cua BDH hai thdng sd Neu coi h ^ la khong doi phanh thi: + Duong 1: La dac tinh thuc te (xe khong co BDH); Vai: + Duong cong Oae: La dac tinh ly tuong cua BDH xe khong tai; + Duong gap khiic 2: La dac tinh lam viec eiia BDH xe khong tai; + Duong cong Obg: La dac tinh ly tuong cua BDH xe diy tai; f=A,-A^.V (2.11) G.a-g,.L G.h^ (2.11) Tir cong thiic (2.11) ta tinh dupe dp vong/ ciia he thong treo cau sau khong tai va cM day tai Tinh dp vpng cho cac diem A, A', B, B' tuang ling voi cac gia tri ^^ tp^., ip^ ta dupe: + Du6ng gip khiic 2': La dac tinh lam viec eua BDH xe dky tai; + Diem a, b la diem bat dau lam viec cua BDH xe khong tai va day tai TAP CHI CO KHI VIET NAM, So nam2014 www.cokhivietnam.vn G„.a-g,.L ip,-GA G„.a-g^.L