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I
1 O AN MON HOC THIET KE OTO GVHD: NGUYEN HU HNG
BAI TAP LN THIET KE OTO GVHD: NGUYEN HU HNG
MUC LUC Trang
I. Nhng van e chung ve ly hp 2
1. Nhiem vu 2
2. Yeu cau 2
3. Phan loai 2
II. Chon phng an thiet ke 3
1. Ly hp ma sat kho 3
2. Ly hp ien t 3
3. Ly hp thuy lc 4
4. Ly hp hon hp 4
5. Ket luan 4
III. Ket cau cac chi tiet chnh va nguyen ly lam viec cua ly hp 4
mot a ma sat kho
1. Ket cau cac chi tiet chnh 4
2. Nguyen ly lam viec 4
IV. Tnh toan cac kch thc c ban cua ly hp 5
1. Xac nh moment ma sat can truyen 5
2. Chon kch thc vanh ma sat 5
3. Lc ep can thiet len cac a e truyen moment ma sat 6
V. Tnh toan cong trt cua ly hp 7
1. Xac nh cong trt cua ly hp 9
2. Kiem tra cong trt rieng 10
3. Kiem tra nhiet o cua cac chi tiet 10
VI. Tnh toan cac chi tiet c ban cua ly hp 11
1. a thu ong 11
2. Vong ma sat 12
3. Moay a thu ong 14
4. Bo phan giam chan 15
5. Truc ly hp 17
6. a ep va a ep trung gian 20
7. Lo xo ep 21
8. on m ly hp 23
9. C cau ieu khien ly hp 24
10. Bac m ly hp 25
11. Than ly hp 25
12. Vo ly hp 25
13. S can bang ly hp 26
VII. Thao, lap, ieu chnh, bao dng, sa cha ly hp 26
I. NHNG VAN E CHUNG VE LY HP:
1.Nhiem Vu:
Ly hp la mot trong nhng cum chu yeu cua oto va may keo, no am nhan cac nhiem vu sau:
- Ngat ng truyen cong suat t ong c en hop so. No cho phep ong c quay trang thai t do ma khong truyen cong suat en hop so.
- Trong qua trnh ngat, no cho phep ngi lai sang so e phu hp vi ieu kien lam viec cua oto.
- Trong qua trnh ong ly hp xay ra s trt ly hp, lam cho qua trnh ong c em du, giam tai trong ong tac dung len hop so, truc va cac he thong khac trong hep thong truyen lc.
- Khi ly hp c ong hoan toan, toan bo cong suat c truyen t ong c en hop so, s trt khong con xay ra.
2. Yeu Cau:
- Truyen c momen ln nhat cua ong c ma khong b trt bat ky thi iem nao. Muon nh vay th momen ma sat cua ly hp phai ln hn momen cc ai cua ong c mot t, ngha la he so d tr momen cua ly hp phai ln hn 1.
- ong em du e tang t t momen quay tren truc cua he thong truyen lc, khong gay va ap cac banh rang. Ngoai ra khi ly hp ong em du th oto, may keo khi hanh khong giat, lam cho ngi lai met, nhat la khi oto chay tren ng pho hoac khi may keo lam viec canh ong nho phai s dung ly hp nhieu.
- M dt khoat va nhanh chong, ngha la cat hoan toan truyen ong t ong c en he thong truyen lc trong thi gian rat ngan. Neu m khong dt khoat th kho gai so em du v momen quay cua ong c va momen quy dan en truc khuyu cua tat ca cac chi tiet chuyen ong cua ong c se truyen mot phan en truc s cap cua hop so, cho nen khi dch chuyen cac banh rang khoi s an khp e gai so khac se rat kho khan tren banh rang ta muon dch chuyen se co tac dung cua lc do momen noi tren sinh ra. M dt khoat va nhanh chong se giam lc va ap cac banh rang.
- Momen quan tnh cua cac chi tiet thu ong phai nho e giam cac lc va ap len banh rang.
- Lam nhiem vu bo phan an toan e tranh tac dung len he thong truyen lc nhng lc qua ln khi gap qua tai.
- ieu khien de dang, lc tac dung len ban ap nho.
- Cac be mat ma sat thoat nhiet tot, am bao s lam viec bnh thng.
- Ket cau n, gian trong lng nho, lam viec ben, ieu chnh va cham soc de dang.
3. Phan Loai:
Ly hp c phan loai theo cac phng phap sau:
Theo cach truyen momen quay t truc ong c en truc cua he thong truyen lc, ngi ta chia ra cac loai ly hp:
+ Ly hp ma sat: truyen momen quay bang cac be mat ma sat.
+ Ly hp thuy lc: truyen momen quay di tac dung cua dong chat long.
+ Ly hp loai nam cham ien: truyen momen quay bang tac dung cua trng nam cham ien.
+ Ly hp loai lien hp: truyen momen quay bang cach ket hp cac loai ke tren.
Ly hp ma sat la loai thong dung nhat va thng c s dung chu yeu tren cac loai oto.
ly hp ma sat, tuy theo hnh dang cua cac chi tiet ma sat ma ngi ta chia ra lam nhieu loai :
+ Ly hp a: phan thu ong gom mot hay nhieu a.
+ Ly hp hnh con: a thu ong co dang con.
+ Ly hp hnh trong: phan thu ong lam theo kieu ma phanh va tang trong.
Loai ly hp hnh con va tang trong ngay nay khong con dung tren oto va may keo na v momen quan tnh cua chi tiet thu ong cua chung ln gay nen tai trong va ap len he thong truyen lc khi ong ly hp.
Tuy theo so a thu ong ma ngi ta chia ly hp ma sat ra mot, hai hay nhieu a.
Ly hp mot a hien nay dung nhieu tren oto va may keo v no n gian, re va momen quan tnh cua chi tiet thu ong be.
oto tuy theo phng phap sinh lc len a ep ngi ta chia ly hp loai lo xo ( ay lc ep sinh ra bi lc ep cua lo xo), loai na ly tam, loai ly tam
Loai na ly tam dung oto du lch va van tai trong c nho v ay momen cc ai cua ong c tng ng vi so vong quay tng oi caoLoai ly tam thng c dung e lam de dang ieu khien oto. Trong cac ly hp loai ly tam th lc ly tam dung e ong m ly hp, con lc e ep la do lo xo, t khi dung lc ly tam e ep a ep. Loai ly hp nay khong c s dung rong rai .
Theo phng phap ieu khien ly hp co the chia ra loai ieu khien bang sc ngi va loai ieu khien t ong.
II. CHON PHNG AN THIET KE:
1. Ly Hp Ma Sat Kho:
Ly hp ma sat loai a rat thong dung va thng c s dung rong rai tren hau het cac loai oto. Ly hp ma sat kho hien nay gom loai mot a hay nhieu a ma sat. Hien nay loai ly hp mot a ma sat co lo xo hnh tru c s dung nhieu.
* u iem: ket cau n gian, am bao thoat nhiet tot, thuan tien cho cong tac bao quan sa cha.
2. Ly Hp ien T:
Qua trnh ong va ngat nh lc ien t cua nam cham.
* u iem: ket cau n gian, de t ong hoa qua trnh ieu khien, mat ma sat hao mon t.
* Nhc iem: bo phan t ong co momen quan tnh ln.
3. Ly Hp Thuy Lc:
Co hai loai: ly hp thuy tnh va ly hp thuy ong.
* u iem: Giam tai trong ong len ong c va he thong truyen lc khi thay oi ot ngot che o lam viec. Tang kha nang chuyen ong cua oto, khong giat khi gai so. ieu khien n gian, khong can ieu chnh khi s dung, t hao mon, cho phep khi ong khi gai so.
* Nhc iem: khong am bao m dt khoat. o trt ln, ket cau phhc tap.
4. Ly Hp Loai Hon Hp :Thng dung loai ly hp ma sat ket hp thuy lc .
* u iem : ket hp c u iem cac loai ly hp tren .
* Nhc iem : ket cau phc tap, gia thanh cao .
5. Ket Luan:
T bon loai ly hp tren, ta thay: vi xe khach 25CN th ly hp ma sat kho loai thng ong, mot a ma sat, dung lo xo tru, co ieu khien, dan ong bang c kh co cng hoa bang thuy lc la phu hp nhat. Do o ta chon loai ly hp nay e thiet ke.
III. KET CAU CAC CHI TIET CHNH VA NGUYEN LY LAM VIEC CUA LY HP MOT A MA SAT KHO:
1. Ket Cau Cac Chi Tiet Chnh:- Vo ngoai ly hp: lam bang gang co nhiem vu bao ve cac bo phan ben trong cua ly hp va c noi lien vi hop so bang bulong va ai oc .
- a b ong: la mot a mong, tren a co ranh xe hng tam chia a thanh nhieu phan bang nhau e giam o cng va tang o an hoi. Tren a co gan cac tam ma sat bang inh tan. a thu ong noi vi moay bang inh tan. Moay c noi vi truc bang then hoa. Ngoai ra tren a b ong con co lo xo giam chan tan so cao va cac tam giam chan tan so thap.
- Mam ep: Che tao bang gang xam, co trong lng kha ln e lam thoat nhiet tot t cac be mat ma sat. a ep phai cng e ep eu len cac vong ma sat. Tren a ep co cho g len hoac cac ong dan hng e nh hng lo xo ep.
- on m: che tao bang thep, co ong cng cao.
on m ta mot au len ly hp, au con lai noi
tiep vi a ep. Tren on m co bat vt ieu chnh.
- Than ly hp: che tao bang thep, c bat cng
vao banh a bang bulong, tren than ly hp co khoan
cac lo e at lo xo ep.
- Lo xo ep: lo xo dang hnh tru, bo tr xung quanh, chu nen tao lc nen len a ep.
2. Nguyen Ly Lam Viec:
- S o nguyen ly cua ly hp:
1: Banh a; 2: Tam ma sat; 3: Vo ly hp;
4: a ep; 5: on m; 6: Ong m ly hp; 7: Lo xo hoi v; 8: Truc ly hp; 9: Ban ap;
10: Lo xo hoi v; 11: Thanh keo; 12: Cang m ly hp; 13: O bi m ly hp; 14: Lo xo ep; 15: Xng a; 16: Giam chan; 17: Moay
Khi khong tac ong vao ban ap ly hp 9, th ly hp trang thai ong. Ly hp c ong lai la do: di tac dung cua cac lo xo ep 14, a ep 4 ep a ma sat ap sat vao mat banh a, lam cho a ma sat quay cung vi banh a nh lc ma sat, thong qua moi ghep then hoa cua moay 17 lam cho truc ly hp (thng la truc s cap cua hop so) quay theo.
Khi ap vao ban ap ly hp 9, nh thanh keo 14 va cang m ly hp 12 ay ong m ly hp 6 va o bi m ly hp 13 ve pha trai, o bi m ly hp t vao cac au on m 5 lam cho a ep dch chuyen ve pha ben phai, luc o a ma sat khong con lien ket vi a chu ong va banh a, t o ngat ng truyen momen t truc ong c en truc ly hp.
Nh vay, khi ong c ang hoat ong neu ang che o ong ly hp th tat ca cac chi tiet cua bo ly hp cung quay vi banh a, neu ang che o ngat ly hp (luc ap ban ap ly hp) th a ma sat va truc ly hp ng yen con vo ly hp, cac on m va mam ep cung quay vi banh a.
IV. TNH TOAN CAC KCH THC C BAN CUA LY HP:
Tnh toan ly hp loai ma sat nham muc ch xac nh so lng va kch thc cac be mat ma sat can thiet e truyen momen quay cua ong c, xac nh lc ep len be mat ma sat, xac nh ty so truyen cua c cau ieu khien ly hp, cung nh xac nh kch thc cac chi tiet khac.
Kch thc cua ly hp c xac nh t c s co kha nang truyen momen quay ln hn momen quay cua ong c mot t. S d phai tnh theo momen ong c la e am bao truyen c het momen quay cua ong c en he thong truyen lc trong trng hp khi a ma sat b dau nhn ri vao, hoac khi cac mat ma sat b hao mon, hoac khi cac lo xo ep b mat tnh an hoi i mot t.
1. Xac nh Momen Ma Sat Can Truyen:
Ml = (.M
ay: M1: momen ma sat cua ly hp, Nm ;
M : momen quay cua ong c, oi vi oto lay momen cc ai cua ong c (M = Memax ), Nm;
( : he so d tr cua ly hp
oi vi oto khach chon ( = 1,9
M1 = 1,9.1050 = 1995 N.m
2. Chon Kch Thc Vanh Ma Sat:
ng knh ngoai cua vong ma sat b gii han bi ng knh ngoai cua banh a ong c. oi vi oto co the chon ng knh ngoai cua vong ma sat theo cong thc thc nghiem sau:
= 53,97 cm, chon D2 = 50 cm.
ay : D2: ng knh ngoai cua vong ma sat, cm;
Memax: momen cc ai cua ong c, N.m;
C: He so kinh nghiem. oi vi oto van tai trong ieu kien s dung bnh thng chon C = 3,6.
Do ng knh tnh toan c la qua ln, do o rat kho che tao, khoi lng se ln, kch thc ly hp ln. V vay thay v dung ly hp mot a ma sat th ta se chon lai kch thc cua a ma sat sau o kiem tra lai theo cac ieu kien lam viec cua ly hp nham giam kch thc cua ly hp nhng van am bao lam viec an toan.
Ban knh ngoai vong ma sat:
Chon R2 = 25 cm
Khi thiet ke ban knh trong cua vong ma sat co the xac nh s bo nh sau:
R1 = (0,53 0,75 )R2
Chon R1 = 0, 53R2 = 13,25 cm
Ban knh trung bnh c xac nh theo cong thc sau:
= 19,73 cm
He so ma sat ( phu thuoc vao nhieu yeu to nguyen lieu cua be mat ma sat, tnh trang cua tam ma sat, nhiet o va ap suat tren be mat ma sat.
e n gian tnh toan co the tha nhan rang he so ma sat ch phu thuoc bi nguyen lieu cua be mat ma sat.
Thng oto hay dung cac be mat ma sat thep vi pherao hoac pherao ong co he so ma sat kho ln nhat la 0,35, nhng tnh en nhng ieu kien nhiet o, toc o trt tng oi lam giam he so o i cho nen khi tnh ta lay ( = 0,25 0,35. Chon ( = 0,3.
Chon so be mat ma sat la p = 2 ( mot a ma sat ).
3. Lc Ep Can Thiet Len Cac a e Truyen Momen Ma Sat M1:
Ap suat tren vong ma sat se la:
Ap suat cho phep tac dung len be mat ma sat oi vi a ma sat lam bang pherao la: [q]=100 250 KN/m2. Vay ap suat tren vong ma sat thoa ieu kien cho phep cua vat lieu.
V. TNH TOAN CONG TRT CUA LY HP:
Khi ong ly hp se co hien tng trt cac a thi gian au cho en khi nao a chu ong va a thu ong quay nh mot he thong ong hoc lien. Khi cac a b trt se sinh ra cong ma sat lam nung nong cac chi tiet cua ly hp len qua nhiet o lam viec bnh thng, lam hao mon cac tam ma sat va nguy hiem nhat la cac lo xo ep co the b ram nhiet o nh vay, mat kha nang ep. V the viec xac nh cong trt trong thi gian ong ly hp la mot ieu can thiet.
Trong qua trnh gai so oto theo s oi so t thap len cao hoac t cao xuong thap ma qua trnh gai co the tien hanh khac nhau. Khi oi so t thap len cao (th du t so I len so II, hoac so II len so III ) toc o goc cua truc khuyu ong c trong khi ong ly hp cao hn toc o goc cua truc s cap hop so, v vay momen quay cua ong c Mm khong nen ln e tranh tang cong trt. Khi oi t so cao xuong so thap toc o goc cua truc khuyu co the thap hn toc o goc cua truc s cap va trong trng hp nay khi ong ly hp can phai co momen Mm nao ay cua ong c e lam ong eu cac toc o goc noi tren. Nhng trong hai trng hp ke tren tuy theo ky thuat cua ngi lai toc o goc cua truc khuyu va truc s cap cua hop so co the ong eu, ngha la (m = ih .(a do o cong trt co the giam en toi thieu.
Khi oto khi ong tai cho s ong eu noi tren khong the thc hien c v (m > 0 va (a = 0. Trong trng hp nay cong trt se cc ai .
Qua trnh ong ly hp co the co hai trong hp sau:
* ong Ly Hp ot Ngot:
Luc o ong c ang quay so vong quay cao th ngi lai tha ot ngot ban ap ly hp. Khi ong tai cho nh vay se sinh ra giat rat ln ln nhat la khi ly hp co he so d tr ( cao. Che o ong ly hp nh the gan giong vi s o tnh toan trnh bay di ay mac du trong thc te can tranh viec ong ly hp ot ngot.
Bieu th (a la toc o cua truc ong c trc luc ong ly hp va (4 la toc o goc sau khi ong ly hp ( cuoi thi ky trt ): He so ha toc o goc tng oi cua truc ong c khi ong ly hp c bieu th la he so nay khi ong ly hp ot ngot se co gia tr k3 = 0,35 0,5.
* ong Ly Hp Em Du:
Khi ong ly hp em du se bao am cho oto khi ong tai cho c em du, ieu nay yeu cau quan trong khi s dung oto. Trong trng hp nay ngi lai nha ban ap ly hp t t ke t khi cac be mat ma sat cham vao nhau, do o tang thi gian trt va tang cong trt. He so k3 trong trng hp nay co gia tr k3 = 0,6 0,9.
Tuy theo che o ong ly hp ma thi gian trt ly hp to se co gia tr sau ay ( khi khi ong tai cho ); khi ong ly hp ot ngot to = 0,6 1,1s, khi ong em du to = 1,6 2,5s. Neu tiep tuc tang toc th toc o cua oto se tang ti gia tr v1 tng ng vi toc o goc cc ai cua truc ong c (2.
Toc o cc ai cua truc ong c c xac nh bi bo phan han che so vong quay at trong oto van tai hoac bi s suy xet cua ngi lai. Tai thi iem ng vi iem d ngi lai nha ly hp, ban ap nhien lieu ( chan ga ) c tha ra va toc o goc cua truc khuyu ong c ha xuong en gia tr (1. Nhp o ha toc o goc cua truc khuyu ong c khi tha chan ga va m ly hp c ac trng bi he so , no bieu th s on nh lam viec cua ly hp. He so nay co gia tr 94 105 1/s2 ( 900 1000 vg/ph/s ).
Trong thi gian t2 gia iem d va e va thi gian chay tiep theo ngi lai tien hanh chuyen so. Ngi lai tha ban ap ly hp ( ong ly hp ) va ong thi an ban ap ga e tang so vong quay (m va toc o goc nay se ha xuong do a ly hp b cuon theo. Tai iem h toc o goc cua truc ong c la (4 va sau o bat au qua trnh tang toc o cua oto so truyen tiep theo. Thi gian to ng vi thi gian trt ly hp khi chuyen so.
Toc o v cua oto at gia tr cc ai so truyen a cho tai iem d. toc o nay se ha xuong trong giai oan t3 do toc o chuyen ong lam giam en toc o ng vi iem e, luc o ly hp v cuon theo th toc o oto bat au tang. Thi gian toan bo khi chuyen so la t4.
e xet cac thong so c ban ac trng cho s lam viec cua ly hp chung ta xet mo hnh cua ong c va he thong truyen lc cua oto trnh bay tren hnh:
Jm : momen quan tnh cua banh a va cua cac chi tiet ong c quy dan ve banh a.
Ja : momen quan tnh cua oto va rmooc quy dan en truc ly hp.
= 0,55 Nms2 ay : Go : trong lng toan bo oto;
Go = (5850+11470).10 = 173200 N
Gm : trong lng toan bo cua rmooc; khong co rmooc;
Gm = 0
ih: ty so truyen tng ng cua hop so. ay oto ang che o khi ong ty so truyen nay ng vi ty so truyen cua hop so tay so 1;
ih=6,142ip :ty so truyen cua hop so phu.Xe khong co hop so phu do o: ip = 1
io : truyen lc chnh;
io =6,17rbx : ban knh lam viec cua banh xe, chon lop xe loai: 8,25-16;
rbx = 0,3562 m;
Momen can chuyen ong quy dan ve truc ly hp:
ay: ( : he so can tong cong cua ng;
( = 0,3
K: he so can khong kh (khi oto chuyen ong vi toc o thap KFv2 = 0 );
(tl : hieu suat cua he thong truyen lc;
(tl = 0,89
( : goc trt cua ly hp;
1. Xac nh Cong Trt Cua Ly Hp:
Cong trt cua ly hp c xac nh theo phng trnh sau:
Tren c s phan tch tren ve hai phng phap ong ly hp chung ta co hai phng phap e tnh cong trt cua ly hp . ay ta chon phng phap tnh toan th hai v no n gian trong tnh toan va phu hp vi ieu kien lam viec cua xe tai.
Phng phap nay tnh en qua trnh dien bien thc te khi ong ly hp gom hai giai oan:
* Tang momen quay cua ly hp M1 t 0 en Ma khi bat au ong ly hp, luc o oto bat au khi ong tai cho.
* Tang momen quay cua ly hp M1 en gia tr ma s trt cua ly hp khong con na.
Cong cua ong c giai oan au cua thi gian t1 se tieu hao cho s trt va nung nong ly hp.
Cong trt giai oan au L1 xac nh nh sau:
Cong cua ong c giai oan th hai cua thi gian t2 tieu ton cho viec tang toc truc b ong cua ly hp va se thang cac sc can chuyen ong cua oto.
Cong trt giai oan th hai se xac nh theo cong thc sau:
Cong trt toan bo cua ly hp se la:
Trong cong thc tren thi gian t1 va t2 c tnh nh sau:
= 0,3 s
= 0,8 s
ay: k: he so ty le, ac trng cho nhp o tang momen cua a ly hp M1 khi ong ly hp;
oi vi oto van tai k = 150 750 Nm/s. Chon k = 540 Nm/s
Gia tr cua A xac nh theo cong thc sau:
= 20,885 (Nms)1/2
(m: toc o goc cua truc ong c;
(m = n(/30 = 2000.(/30 = 209,4 (s-1)
(a: toc o goc cua truc ly hp.Khi khi ong (a = 0
Toc o goc cua truc ong c khi ong ly hp co the tha nhan khong oi va bang toc o goc ng vi momen cc ai cua ong c.
( L = 33,03 kJ
T cac cong thc tren ta thay rang, cong trt tang ang ke khi tang hieu so ((m - (a). e giam cong trt ngha la giam hao mon oi be mat ma sat cua ly hp th ngi lai phai lam the nao e giam hieu so ((m - (a ). Gia tr ln nhat cua hieu so nay xay ra khi khi ong oto tai cho v luc o (a=0.
2. Kiem Tra Cong Trt Rieng:
oi vi oto cong trt rieng c tnh theo cong thc:
= = 242,5 kJ/m2Vay Lo = 242,5 < [Lo] = 150 250 kJ/m2 . Thoa man yeu cau ve cong trt rieng cho phep.
3. Kiem Tra Nhiet o Cua Cac Chi Tiet B Nung Nong Trong Qua Trnh Ly Hp B Trt:
Trong o:
T : nhiet o tang len cua chi tiet, oK;
( : he so xac nh phan cong trt e nung nong chi tiet can tnh;
( = 0,5 ( oi vi ly hp 1 a ).
C = 500 J/Kg.o
L : cong trt toan bo;
ga :khoi lng cua chi tiet b nung nong , chon ga = 10,6 kg;
T = = 3,2 oK
Vay ly hp thoa ieu kien nhiet o cho phep la t 8 10oK.
VI. TNH TOAN CAC CHI TIET C BAN CUA LY HP:
1. a Thu ong:
oto va may keo thng dung loai ly hp mot hai a thu ong vi tam ma sat co he so ma sat cao la nham muc ch giam kch thc va giam kim loai cua ly hp. Con ly hp nhieu a co the lam a thu ong co tam ma sat hoac khong co tam ma sat. Ly hp vi a thep khong co tam ma sat thng lam viec trong dau e tang kha nang thoat nhiet (ly hp nay at trong hop so hoac truyen ong truc thu cong suat ).
Ly hp mot a cua oto hien nay ch dung a thu ong loai an hoi. o an hoi cua a thu ong am bao bang cach cho no nhng hnh thu nhat nh hoac dung them nhng chi tiet ac biet co kha nang lam giam o cng cua a. e giam o cng, tren a thu ong co xe cac ng hng tam. Cac ng xe nay chia a thu ong ra nhieu phan. Cac phan nay uon ve cac pha khac nhau. So lng ng xe la 12 tuy theo ng knh cua a. Cac ng xe nay lam cho a thu ong venh khi b nong len luc lam viec.
e giam chieu rong (tang o an hoi ) cho noi tiep cua phan ngoai vi phan trung tam cua a th ng xe co the lam theo hnh ch T. Khi at lo xo tam gn song gia a thu ong va tam ma sat th o cng tren be mat cua a thu ong tng oi eu hn.
Neu thay oi o cng cua lo xo tam co the anh hng en o cng chung cua a thu ong.
e tang o tiep xuc ong eu va tang be mat tiep xuc cua tam ma sat trong qua trnh ong ly hp th so lo xo tam khong c nho hn 6. Khi at lo xo tam gia a thu ong va tam ma sat ma muon m ly hp dt khoat th hanh trnh dch chuyen cua a ep phai tang len mot t. ieu nay co the thc hien c neu van gi nguyen hanh trnh cua ban ap bang cach giam ty so truyen cua he thong dan ong ly hp va nh vay phai tang lc tac dung len ban ap. Cung v the ma cac ly hp truyen momen quay ln khong dung cac a thu ong an hoi co lo xo tam.
a thu ong c noi vi truc ly hp nh moay, moay noi vi a thu ong bang inh tan rat t khi dung bulong. a thu ong co the lam vi bo phan giam chan hoac khong co giam chan. Khi at bo phan giam chan th ket cau cua a se thay oi, trong lng va momen quan tnh se tang len. a thu ong can co tnh chat an hoi ln e tang em du khi ong ly hp cho nen chung c che tao bang la thep co thanh phan cacbon tiep noi vi phan thu ong cua ly hp bang cac ranh then hoa th cac ranh then hoa c tnh theo dap tren c s lam the nao cho a thu ong khong sinh ra tren be mat trong nhng vet han, do o ng suat dap cho phep trung bnh va cao ( thep loai 45 en 85 ) c toi trong dau va ep e tranh venh. Lo xo tam c che tao t la thep mong co thanh phan cacbon cao.a thu ong c che tao bang thep 50, chieu day a thu ong la 2mm, sau khi che tao c toi trong dau va ep e tranh venh.
a thu ong c noi vi truc ly hp nh moay, moay noi vi a thu ong bang cac inh tan bang thep. inh tan co dang hnh tru, bo tr theo vong tron, theo ket cau ta co ng knh qua tam inh tan la D =130mm. ng knh cua inh tan d =8mm, so lng inh tan la: 6.
* Lc tac dung len mot inh tan :
== 371 N
* ng suat cat:
== 7,38 MN/m2Vay =30 MN/m2* ng suat chen dap:
== 23,2 MN/m2 vi: :chieu day tam ghep.
d : ng knh inh tan.
Vay =80 MN/m2.
Nh vay inh tan a chon ap ng u ieu kien ben.
2. Vong Ma Sat:
Vong ma sat gi vai tro quan trong khi ly hp lam viec va can phai co cac ac tnh sau:
- am bao he so ma sat can thiet va he so ma sat t b anh hng khi co s thay oi nhiet o, toc o o trt va ap suat tren be mat.
- Co kha nang chong mon ln nhiet o cao (en 573 623 oK ).
- Tr lai kha nang ma sat nh ban au c nhanh chong sau khi b nung nong hoac b lam lanh.
- Lam viec tot, nhiet o cao t b sui cac chat dnh, khong co mui khet, khong b xop.
- Co tnh chat c hoc cao (o ben, o an hoi va o deo ).
Nguyen lieu hien nay thng dung e lam vong ma sat la pherao, pherao ong va trong thi gian gan ay tren oto va may keo bat au s dung vong ma sat bang kim loai s.
Chon vat lieu lam vong ma sat la pherao. Chon chieu day tam ma sat la 3,5mm. Vong ma sat bang pherao co o dan nhiet thap, he so ma sat cua chung phu thuoc vao nhiet o.
Trong ieu kien s dung bnh thng th vong ma sat che tao bang pherao bao am kha nang lam viec tot va che tao re. Vong ma sat bang lim loai s ch nen dung trong trng hp can thiet v no che tao bang kim loai mau nen at tien.
Cac tam ma sat bang pherao c gan vi a thep bang cach dan hoac bang inh tan. Phng phap dan t c dung v chat dnh ket ac biet dung e dnh tam ma sat vao a se dnh rat chat va khi tam ma sat b mon th khong the tach ra khoi a e thay bang tam ma sat khac c. Trong trng hp nay thng phai thay toan bo a thu ong. Do o ta chon phng an gan cac tam ma sat bang inh tan. inh tan lam bang ong o, thau mem hoac bang nhom, ay ta chon vat lieu lam inh tan bang ong thau vi ng knh inh tan la: d = 4 mm theo dang hnh ong.
Chon so lng inh tan tren mot a la: 24 inh, chia lam hai day
Khi gan cac tam ma sat th au cac inh tan phai thut xuong khoi be mat tam ma sat khoang 2 mm e tranh s co sat cac inh vao a ep hoac banh a khi tam ma sat b hao mon.
Ban knh vong inh trong : R1 = 105 mm.
Ban knh vong inh ngoai : R2 = 155 mm.
Lc tac dung len mot inh tan vong trong :
vi n: so inh tan moi day, n = 12.
Lc tac dung lem mot inh tan vong ngoai :
Moi ghep inh tan co the b h hong do :
* inh tan b cat
* inh tan b chen dap
ng suat cat :
ng suat chen dap :
Vi s = 3,5 mm : chieu day tam ghep;
Vay cac inh tan eu thoa cac ieu kien ben cho phep ve ng suat cat va ng suat chen dap .
3. Moay a Thu ong:
Moay a thu ong cua ly hp oto c at tren truc then hoa cua ly hp theo lap ghep trt.
e co the mai nhan de dang cac mat ben cua then vi ban knh trong cua truc then hoa ngi ta lam ranh hoac ln chuyen tiep eu an vi ban knh r. Hnh dang cua then anh hng en o vng ben cua truc ly hp. Neu chuyen tiep ot ngot th chan then se co ng suat cuc bo rat ln. Cac then co the lam dang than khai hoac vuong goc. Dang then than khai am bao o ben va o chnh xac trung tam tot hn loai vuong goc. Ta chon rang then hoa dang than khai v co nhieu u iem:
- Sc ben moi cao do chan ren day hn va khong co goc ln ot ngot nen ng suat tap trung chan then nho (tan so tap trung ng suat giam) so vi rang hnh ch nhat.
- Cac phan t moi ghep c che tao bang cac phng phap hoan thien hn do o o chnh xac cao hn.
- am bao o ong tam cao.
Cac then cua moay tnh theo dap va cat. Khi co nhieu a thu ong va moi a nam tren moi moay rieng biet th coi nh momen quay truyen en moi a eu bang nhau. Moay a thu ong che tao bang thep 40 hoac 40X, chon loai thep 40X.
Lc tac dung len ban knh trung bnh cua cac then oi vi mot moay la:
Trong o:
Q : lc tac dung len then, N;
M : Momen cc ai cua ong c;
M = Memax = 290 N.m
Z1 : so lng moay;
Z1 = 1
D : ng knh ngoai cua cac then truc ly hp;
D = 40 mm
d : ng knh trong cua cac then tren a thu ong, d=32 mm;
( Q = =16111,1 N.
ng suat dap cua then se la:
= = 9,58 MN/m2 < [ (d ] = 20 MN/m2Trong o:
Z2: so lng then cua moay;
Z2 = 10
l : chieu dai lam viec cua then;
l = 42 mm
ng suat cat cua then la:
= =7,67 MN/m2 < [( ] = 10 MN/m2Trong o:
b : chieu rong cua chan then;
b = 5 mm
Vay then thoa ng suat cho phep.
4. Bo Phan Giam Chan:
Giam chan c dung trong ly hp e tranh cho he thong truyen lc cua oto khoi nhng dao ong xoan cong hng sinh ra khi co s trung mot trong nhng tan so cua dao ong s hu cua he thong truyen lc vi tan so cua lc gay nen bi s thay oi momen xoan cua ong c.
Chi tiet an hoi cua giam chan dung e giam o cng cua he thong truyen lc, do o giam dc tan so dao ong ban than cua he thong truyen lc va triet tieu c kha nang xuat hien cong hng tan so cao. Do o cng toi thieu cua chi tiet b an hoi cua giam chan b gii han bi ieu kien ket cau cua ly hp cho nen he thong truyen lc cua oto khong the tranh khoi cong hng tan so thap. Bi the ngoai chi tiet an hoi ra can phai co chi tiet thu nang lng cua cac dao ong cong hng tan so thap bang phng phap ma sat goi la chi tiet ma sat.
Giam chan c dung nhieu la loai chi tiet co an hoi bang lo xo c at tiep tuyen trong cac lo khoet cua a thu ong va co chi tiet ma sat bang thep hoac bang nguyen lieu ma sat khac. So lng lo xo hnh tru thng t 612 chiec. e tang hieu qua giam chan, co khi giam chan c thiet ke vi o cng thay oi, ban au o cng t hn va sau o tang dan. Momen cc ai Mmax gii han o cng toi thieu cua lo xo (khi cac vong lo xo sat vao nhau) thng lay bang momen xac nh theo ieu kien bam ( = 0,8.
Chon loai giam chan lo xo thep hnh tru, so lng z = 6 cai.
Vat lieu: thep mang gan co = 16001700.
= = 211,72 N.m
ay: G2: Trong lng tac dung len cac banh chu ong, N;
G2 = 0,55.G = 0,55.42500 = 23375 N
rbx: Ban knh lan cua banh xe, m;
rbx = 0,3562 m
io: ty so truyen cua truyen lc chnh;
io = 6,05
ih1: ty so truyen cua hop so so 1;
ih1 = 5,2
Lc tac dung len lo xo giam chan:
= = 588 N
Trong o:
R : Ban knh vong tron at lo xo giam chan;
R = 60 mm
n : so lng lo xo giam chan;
n = 6
Chon ch so cua lo xo la:
C = D/d = 5
He so tnh en s tap trung ng suat;
k = 1,3
ng suat cat cho phep cua vat lieu;
[(x ] = 0,5.(b = 0,5 . 1600 = 800 MPa
ng knh day lo xo:
= 3,5 mm
Chon d = 4 mm
ng knh trung bnh cua vong lo xo:
D = d . C = 4.5 = 20 mm
Lc ep nho nhat khi lap lo xo vao lo:
Plxmin = 50 N
Goc xoay tng ng cua may khi lo xo chu tai:
( = 5oKhoan dch chuyen cho phep cua lo xo luc lam viec:
x = R. ( = 60. 5.( / 180 = 5,22 mm
So vong lam viec cua lo xo:
EMBED Equation.3 vong
Chon i = 4 vong
Vi G : Momen quan tnh oc cc cua tiet dien day lo xo;
G = 8.104 MPa
So vong toan bo cua lo xo:
io = i + 1,5 = 5,5 vong
Chieu dai cua lo xo khi cac vong st nhau:
lt = (io 0,5).d = 20 mm
Chieu dai cua lo xo khi cha chu tai:
lo = lt + i.(t-d)
Trong o:
t : bc lo xo khi cha chu tai;
t = d+1,2./i
: bien dang ln nhat cua lo xo;
=
mm
t = 4+1,2.7,35/4 = 6,205 mm
Vay lo =20 + 4.(6,205-4)= 28,8 mm
5. Truc Ly Hp:
Do oto, ly hp va hop so c bo tr lien nhau e am bao can gat so nam vao v tr buong lai v the tren truc ly hp con co banh rang chu ong luon luon an khp cua hop so va thng chung c noi vi nhau qua khp 1 noi hoac truyen ong khp cacang cho nen truc ly hp khong co banh rang chu ong cua hop so.
Truc ly hp phai am bao ong tam vi truc khuyu ong c. Trong a so trng hp o ong tam c thc hien nh hai o bi, mot at lo khoet cua banh a hoac truc khuyu ong c, con mot c at vo hop so. e am bao o ong tam cua hai o bi khi lap ghep ta nen lam chot nh v vo ong c va vo ly hp.
oto tren truc ly hp co banh rang chu ong cua hop so banh rang nay co the la banh rang thang hoac banh rang nghieng. Goi cua truc ly hp c at vao banh a. Goi nay khong nhan lc chieu truc. e truc ly hp khong chuyen dch theo chieu truc do thanh phan lc chieu truc banh rang gay nen, can at chi tiet nh v nam tren vo hop so.
Goi cua truc ly hp thng c at tren o bi hng knh mot day.
Trong a so trng hp oto boi trn bi ang trc cua truc ly hp bang cach cho dau m khi thao ly hp, m nay dung trong suot thi gian phuc vu cho en khi thao ly hp lan khac. Trong trng hp nay o bi nen co vong bao ve hay vong chan dau e gi m boi trn bi trc cua ly hp c thc hien nh vu m bat tren truc ly hp qua ranh tam truc hoac bang day n at ng tam truc khuyu.
Truc ly hp cua oto thng c noi vi moay cac a thu ong nh then hoa. Trong mot vai trng hp e n gian viec sa cha truc, cac then c kha tren mot vanh rieng, vanh nay noi vi truc bang inh tan.
Neu tren truc co banh rang th cua banh rang se sinh ra cac momen uon, xoan phu them. Trong trng hp nay can phan tch tac dung cho cu the e ve bieu o momen xoan va momen uon tac dung len truc.
Xac nh ng knh truc ly hp:
Vi : Mx : moment xoan tac dung tai tiet dien nguy hiem;
Mx = Memax = 290 Nm
: ng suat xoan cho phep ( = 80120 N/mm2), chon = 80 N/mm2;
Chon d = 28 mm
Chon s bo banh rang chu ong:
Chon modun rang m = 4
Goc an khp =
Goc nghieng rang
EMBED Equation.3 Chon so rang z =20 rang
Vay ng knh vong chia la:
Khoang cach truc s bo:
Chon A =124 mm
S o lc tac dung len truc ly hp:
Tai trong tac dung len truc len truc ly hp:
- momen xoan cua ong c: Memax = 290 Nm.
- Lc tac dung len banh rang chu ong:
* Lc vong:
Ft ==7631.6 N
* Lc hng tam:
F r==2920 N
* Lc doc truc:
Fa==2479 N
Xac nh phan lc tai o truc:
ng suat tong hp do momen xoan va momenuon tac dung tai tiet dien nguy hiem:
ay : Mx : momen xoan tac dung tai tiet dien nguy hiem, MN/m;
Mu : Momen uon tac dung tai tiet dien nguy hiem, MN/m;
d : ng knh tai tiet dien nguy hiem, m;
Mu2 = Mx2 +My2 Tx = 290 Nm
Xet tai tiet dien B:
Chon =70 N/mm2
Chon ng knh truc tai tiet dien B la: d = 45 mm.
6. a Ep Va a Ep Trung Gian:
a ep ngoai va a ep trung gian phai quay cung vi banh a, khi m hoac ong ly hp phai co kha nang chuyen dch theo chieu truc, bi the chung c noi vi banh a bang chot 1, gan than ly hp bang chot 2, c van vao banh a bang chot 3 c ep chat vao banh a hoac bang g loi cua a c ty vao cho lom 4 cua than ly hp hoac bang nhng phng phap khac.
Khi ong c lam viec cac a nay quay cung banh a cho nen khi tnh momen quan tnh cua cac trong khoi quay cua ong c can phai them momen quan tnh cua cac a nay.
a ep ngoai va a ep trung gian chu ong phai co trong lng kha ln e lam thoat nhiet tot t cac be mat ma sat, bang cach hut nhiet vao ban than chung roi truyen ra khong kh.
Cac a ep phai cng e am bao ep eu len cac vong ma sat. e thoat nhiet tot oi khi tren a lam cac gan nh canh quat e gay gio.
a ep ngoai va a ep trung gian khi lam viec chung vi cac vong ma sat phai chong mon tot, khong c xc cac be mat lam viec, de che tao, thoat nhiet tot va co o ben c hoc cao so vong quay ln. Bi v cac a ep co hnh dang tng oi phc tap (co phan loi e noi vi vo ly hp, co cho g len e nh v hoac hng lo xo ep, co cac cho loi ra e noi vi on m hay co cac ranh thong gio ) cho nen thng c ut bang gang xam co cau tng peclit.
e tang o ben, o cng vng va tuoi tho cac a ep cua ly hp nay ngi ta che tao chung bang gang hp kim.
7. Lo Xo Ep:
Ly hp oto s dung lo xo hnh tru, con va lo xo a. Lo xo tru c s dung rong rai va co the at xung quanh hay trung tam. So lng va ng knh lo xo c chon nh the nao e am bao lc ep can thiet len cac a va e bo tr hp ly tren da ep, nen thng at t 912 cai lo xo.
Ta chon lo xo tru va c bo tr xung quanh, so lng la 12 cai.
Bo tr lo xo xung quanh co khuyet iem la neu nh trong trng hop o cng cua lo xo khac nhau th lc ep cua chung se khac nhau do o lam cho lc ep cac be mat ma sat khong ong eu. Muon tranh khuyet iem nay can phai tang yeu cau khi chon cac lo xo va phan loai thanh bo. Muon cho ly hp lam viec tot can phai lam bo phan e hng lo xo khi lap ghep, v du lam g noi len than ly hp hoac a ep. Cac g nay tranh cho lo xo khoi bat ra di tac dung cua lc ly tam ln. Dung lo xo trung tam co u iem la am bao cac mat ma sat ep eu hn. Ly hp vi lo xo trung tam hnh con co u iem so vi hnh tru la kch thc chieu dai be hn va ket cau gon gang hn. Khi s dung cac lo xo ep trung tam hnh tru hoac hnh con th bo tr o bi ep cua c cau ieu khien se phc tap, bi v cac lo xo phai at tren truc ly hp.
e tranh nung nong cac lo xo hnh tru bo tr xung quanh a ep th di mat ta cua lo xo vao a ep co at tam em cach nhiet. Chieu day cua tam em nay khoang 3 mm.
Cac lo xo ly hp thng ong c at trang thai ep ban au. Lc ep chung cua cac lo xo khi tat ca cac lo xo eu tac dung len a ep phai bang lc P can thiet e truyen momen quay.
= 6957 N
Khi m ly hp cac lo xo ep b bien dang them, do o lc ep len a se ln hn na. Ta coi rang bien dang them cua lo xo khi m ly hp se lam tang lc ep len 20%. Do o lc tnh toan cua lo xo c tha nhan khong phai la P ma la P:
= 8348,4 N
Lo xo cua ly hp thng c che tao bang thep cacbon 85, thep mangan 65. ng suat cho phep [(]=500 700 MN/m2.
Lo xo c tnh toan theo cac phng phap sau:
Tnh lc tac dung len mot lo xo Po:
= 696 N
ay : P : lc tac dung len tat ca cac lo xo khi a m ly hp;
n : so lng lo xo chon theo ac iem ve ket cau. Chon n = 12.
Chon ch so cua lo xo:
C = D/ d = 5
He so tnh en s tap trung ng suat:
k = 1,3
ng suat xoan cho phep cua vat lieu:
[(x ] = 600 MPa
ng knh day lo xo:
= = 4,4 mm
Chon ng knh day lo xo la d = 5 mm
ng knh trung bnh cua vong lo xo:
D = d . C = 5 . 5 = 25 mm
Lc ep nho nhat khi lap lo xo vao lo:
Plxmin = P/n = 6957 / 12 = 580 N
Lc ep ln nhat khi lo xo lam viec:
Plxmax = P0 = 696 N
Khoan dch chuyen cho phep cua lo xo luc lam viec:
x = 2 mm
So vong lam viec cua lo xo:
= 6,8 vong
Chon i = 7 vong.
Vi: G : Momen quan tnh oc cc cua tiet dien day lo xo;
G = 8.104 MPa
So vong toan bo cua lo xo:
io = i + 2 = 9 vong
Chieu dai cua lo xo khi cac vong st nhau:
lt = (io 0,5).d = 42.5 mm
o mem cua lo xo:
(1 = 8C3 /(G.d) = 0,0025
Chuyen v ln nhat cua lo xo khi chu lc:
(max = (1.i.Pmax = 0,0025.7.696 = 12,18 mm
Bc lo xo khi cha chu tai:
t = d + 1,2.(max /i = 7,08 mm
Chieu dai cua lo xo khi cha chu tai:
lo = lt + (t d).i = 42,5+ 7.(7,08-5) = 57,06 mm
8 .on M:
Cac on m ly hp c ta mot au tren ly hp, au con lai noi tiep vi a ep. on m dung e m ly hp, no can co o cng tot, nhat la trong mat phang tac dung lc, con ong em du ly hp la nh dung a thu ong an hoi. Chon so lng cac on tuy theo kch thc ly hp va khong t hn ba chiec.
e giam tieu hao do ma sat khi m ly hp th cac on c at tren cac chan ta hay tren cac o thanh lan hnh tru hay cac ngong. O trt khong c dung v no can phai boi trn, khi quay di tac dung cua lc ly tam dau se ban tung toe hoac khi ly hp b nong th dau se chay, do o dau co the ri vao vong ma sat lam anh hng en kha nang lam viec cua chung.
Khi a ep chuyen ong tnh tien th cac on m ly hp phai quay t do goi hoac cho noi cua on m vi a ep hoac ca hai cho.
Khi m ly hp, bac m phai t cung mot luc len cac on m. Muon the cac au trong cua chung phai nam trong mot mat phang. ieu chnh cac au trong cua on m tien hanh bang cach dung chot va ecu nam au ngoai cua cac on, bang cach thay oi v tr goi trung gian hoac bang cach dung cac bulong ieu chnh van vao cac au trong cua on.
oi vi cac on m che tao bang phng phap dap, ngi ta dung thep la co thanh phan cacbon thap, thep 80, sau o em xianuya hoa.
Khi tang so vong quay cua truc khuyu th ap lc tac dung len a se tang do lc ly tam Plt cua trong khoi phu on m ly hp sinh ra. Lc ly tam cua on m xac nh theo cong thc sau:
ay : GP: Trong lng cua on ke ca trong khoi phu, N;
n : So vong quay cua truc khuyu ong c, v/ph;
R : Khoang cach t trong tam cua on en truc quay, m;
g: Gia toc trong trng, g = 9,81 m/s2 ;
Lc ep P1 len a ep do lc ly tam cua mot on sinh ra la:
P1= Plt.a/b
Trong khoi phu cua cac on c che tao nh the nao e sinh ra lc ep P1 phoi hp vi lc ep lo xo co the sinh ra momen quay ma sat ln hn momen cc ai cua ong c khi ong c lam viec so vong quay ng vi momen cc ai.
Lc ep chung len a ep do tac dung cua lc ly tam va cua lo xo ep la:
ay : P : Lc ep do lo xo gay nen, N;
c : So lng on m ly hp, chon c = 6 on m;
9. C Cau ieu Khien Ly Hp:
oi vi loai ly hp thng ong:
e ieu khien ly hp thng ong ngi ta dung dan ong loai c kh hoac c kh co cng hoa thuy lc hay cng hoa chan khong.
Ta chon c cau ieu khien ly hp bang c kh co cng hoa thuy lc.
Chon: a = 190 mm c = 50 mm e = 95 mm
b = 55 mm d = 45 mm g = 20 mm
ty so ng knh xy lanh: d2/d1 = 1,5
oi vi dan ong c kh co cng hoa thuy lc th ty so truyen cua dan ong id va hanh trnh cua ban ap ib xac nh nh sau:
Va
ay: F : Hanh trnh cua a ep khi m ly hp;
( : khe h gia on m ly hp va bac m, hay la hanh trnh chay khong cua bac m ly hp.
Hanh trnh cua a ep khi m ly hp c xac nh nh sau:
F = (f.p
ay: (f : khe h gia oi be mat ma sat khi ly hp m hoan toan.
oi vi oto (f = 0,75 1 mm, chon = 0,8mm.
p: So lng oi be mat ma sat, p = 2.
Khe h ( can thiet e ly hp co the lam viec c khi cac vong ma sat b hao mon ( v khi o khe h ( giam va a ep co the khong ep c a thu ong vao banh a do on m ly hp b ham bi bac m ).
oi vi oto tuy theo o hao mon cho phep cua vong ma sat khe h ( = 24 mm, chon = 2,5mm.
Vay:
Lc tac dung len ban ap Pb e m ly hp xac nh theo cong thc sau:
ay: P: tong cac lc do lo xo ep tac dung a ep cuoi thi ly m ly hp;
P = 8348,4 N
(d : hieu suat cua dan ong;
Thng (d = 0,7 0,8 , chon = 0,8.
oi vi oto van tai lc tac dung len ban ap ly hp khi m hoan toan khong c qua 200 N, con oi vi oto du lch lam viec ng pho khong c qua 150 N. Hanh trnh toan bo cua ban ap ly hp oi vi oto van tai khong qua 180 mm, oi vi oto du lch khong qua 150 mm.
Ban ap ly hp che tao bang cach uc gang ren hoac dap t thep 20 hoac thep 25.
10. Bac M Ly Hp:
Bac m la bo phan trung gian e c cau ieu khien co the tac dung len on m e m ly hp.
bac m co the co o bi t hay o bi hng knh. Cung co khi ngi ta thay o bi bac m bang vong t che tao bang than ep co tham m. Dung vong ty che tao bang than ep se khong can boi trn khi s dung. Boi trn cac o bi va cac chi tiet trt cua bac m c tien hanh nh vu m at ngay tren o bi hoac nh vu m at ca so cua ly hp qua ong mem, hoac nh vong n hut dau t buong cha dau.
cac ket cau hien nay, o bi t khong co cho e bm m. Trong trng hp nay o bi c at trong mot vong bang thep la do o o bi khong b tach ri va c bt kn buong cha m. Buong cha m co u m e boi trn trong suot thi ky lam viec cua oto cho en khi ai tu.
11. Than Ly Hp:
Than ly hp c gan vi banh a va dung lam mat ta cho cac lo xo ep cung nh lam goi cho cac on m. e lam mat ly hp ngi ta khoet cac ca so than. Than che tao bang thep 08 hay 10, t khi che tao bang thep uc hoac gang uc.
12. Vo Ly Hp:
mot vai ket cau cua oto na khung hoac khong khung vo ly hp va hop so lam thanh mot khoi lien. cac oto khac co khung th vo ly hp lam thanh mot khoi rieng biet.
Hnh dang, kch thc cua vo va cac ca so e thong gio phu thuoc vao ket cau cua ly hp.
Vo ly hp co loai lien mot khoi hoac loai ghep. loai lien mot khoi vo c uc bang gang, con loai ghep th ca hai phan cua vo co the cung c uc bang gang hoac phan di dap bang thep la.
Vo ly hp c nh v vi vo ong c theo vo banh a nh cac chot nh v va nh v oi vi hop so theo mat bch cua nap o bi truc s cap hop so.
13. S Can Bang Ly Hp:
e tranh nhng hien tng khong tot do lc ly tam sinh ra can phai can bang cac chi tiet cua ly hp khi che tao. o chnh xac khi can bang phu thuoc so vong quay cua ong c, bi khe h cua cac cho noi a ep vi than ly hp va bi kch thc cua ly hp.
a ep cua oto du lch c can bang vi o chnh xac (1,52 )10-3 Nm, cua oto van tai co the en (37 )10-3 Nm. a thu ong khi lap cung vi moay c can bang vi o chnh xac (34 )10-3 Nm va thong thng ch can bang a thu ong ly hp oto du lch. Can bang bang cach khoet cac lo nam xa tam quay e bt lng kim loai phai khoet.
VII. THAO, LAP, IEU CHNH, BAO DNG, SA CHA LY HP :
* Thao:
- Thao hop so.
- Lay truc ly hp ra khoi a ly hp.
- Thao cac bulong ghep vo ly hp vi vo banh a e lay vo ly hp ra. Tren vo ly hp co mat bch va bac m ly hp.
- Thao cac bulong lap than ly hp vi banh a va cac ai oc goi trung gian cua on m e lay than ly hp va cac lo xo ep ra.
- Lay a ep va a thu ong ra khoi vanh banh a.
- M cac vong chan cac chot cua on m e lay on m ra khoi a ep.
* Lap:Ngc vi trnh t thao tren.
* ieu Chnh Ly Hp:- Trong qua trnh lap rap, ta phai ieu chnh v tr cua cac goi trung gian cua cac on m bang cac ai oc cau, sao cho cac au on m ong phang e chung co the tiep xuc mot cach ong thi vi bac m ly hp.
- ieu chnh khe h gia a ep trung gian va chot han che la 1mm.
- ieu chnh khe h t do gia au on m va bac m ly hp la 2mm.
* Bao Dng Ly Hp:- Cac o bi phai c boi trn nh ky.
- nh ky ieu chnh khe h t do gia au on m va bac m ly hp.
* Sa Cha Ly Hp:Trong qua trnh s dung, c cau ly hp co the phat sinh nhng h hong sau:
- Ly hp ong khong hoan toan (b trt ).
- Ly hp ngat khong hoan toan.
- Ly hp ong ot ngot.
Phng phap bao dng sa cha:
- Khi ly hp b trt, momen xoan t truc ong c se khong truyen hoan toan cho cac banh chu ong (ac biet khi oto co hang leo len doc ). Ket hp vi viec tang so vong quay cua truc khuyu ong c khi nha ban ap ly hp, oto hau nh van khong nhch khoi cho hoac tang toc rat cham, oi khi oto chay b giat va trong buong lai ngi thay mui khet cua cac tam ma sat cua a b ong. Nguyen nhan ly hp trt la:
+ Khong co khe h gia bac m ly hp va on m ly hp khi nha ban ap ly hp do a chu ong khong ep hoan toan vao a thu ong; e khac phuc h hong nay, can kiem tra va ieu chnh hanh trnh t do cua ban ap ly hp.
+ a ly hp b dnh dau: h hong nay la do o truc cua bac m ly hp boi qua nhieu m hoac do dau ro chay qua o truc chnh pha sau cua truc khuyu; trong trng hp nay lc ma sat giam i ot ngot va cac a ly hp b trt. Muon khac phuc h hong nay phai thao ri bo ly hp dung xang ra sach cac a, con ma cac tam em dung ban chay sat hoac dua anh sach.
+ Be mat ma sat cac a ly hp b mon: neu tam ma sat a ly hp mon t th co the khac phuc c bang cach ieu chnh lai hanh trnh t do cua ban ap ly hp; neu tam ma sat mon nhieu th phai thay mi.
+ Cac lo xo ep yeu hoac gay: phai thay mi cac lo xo.
- Bo ly hp ngat khong hoan toan:
Dau hieu cua h hong nay la khi gai cac so co kem theo tieng nghien rt cua cac banh rang hop so, trong o khong loai tr kha nang cac banh rang b st me. H hong nay co the do nhng nguyen nhan:
+ Khe h gia bac m ly hp va on m ly hp qua ln. H hong nay co the khac phuc bang cach ieu chnh lai hanh trnh t do cua ban ap ly hp.
+ Cac a b ong b lech hoac b venh, khe h khong eu nhau gia cac a do chung b venh (con rieng tng cho th khong co khe h ) h hong nay thng phat sinh khi bo ly hp qua nong sau khi no b trt. Khac phuc bang cach thay mi cac a cong venh.
+ a ep b lech: khi ngat ly hp a chu ong van tiep tuc ep tng phan vao a b ong. H hong nay phat sinh khi cac au trong cua on m ly hp khong nam tren mot mat phan, trong trng hp nay can phai ieu chnh v tr cac on m ly hp.
- Bo ly hp ong ot ngot: Mac du nha chan ban ap cham va em nhe, oto chuyen banh b giat. H hong nay co the xay ra trong trng hp bac m ly hp b ket. Khi nha ban ap ly hp, bac m se di chuyen khong eu, con khi lc lo xo thang s ket cua bac m th bac m se di chuyen nhanh, giai phong on m ly hp mot cach ot ngot va cac a b ep lai mot cach nhanh chong. S ong ot ngot cua bo ly hp cung co the do nhng ng ran nt nho tren cac a chu ong gay nen sau khi chung b qua nong. Muon khac phuc nhng h hong tren phai thay mi nhng chi tiet b hong.
TAI LIEU THAM KHAO
1. Nguyen Hu Can Phan nh Kien : Thiet Ke Va Tnh Toan OTo-May Keo, tap I va II, Nha Xuat Ban Giao Duc 1996.
2. Trnh Chat Le Van Uyen : Tnh Toan Thiet Ke He Thong Dan ong C Kh, tap I va II, Nha Xuat Ban Giao Duc.
2. Nguyen Hu Loc : C S Thiet Ke May, tap I.
4. Nguyen Hu Can D Quoc Thnh Pham Minh Thai Nguyen Van Tai Le Th Vang : Ly Thuyet Oto May Keo, Nha Xuat Ban Khoa Hoc Va Ky Thuat.
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