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7/29/2019 Ly Thuyet He Thong Phanh
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H thng phanh3.2.1 Cng dng
H thng phanh ca xe dng lm cho xe ang chy -c gim bt tc
hoc -c dng bnh nhanh, n cn gi cho xe ng yn ti ch k c khiang nm trn -ng dc.
H thng phanh m bo cho xe chy an ton tc cao. Nh m nng
cao nng sut vn chuyn.
3.2.2. Phn loi
Theo ph-ng php iu khin, h thng phanh chia thnh;+ Phanh chn; -c iu khin bng chn, phanh chn to ra lc tc
ng ln cc guc phanh. Phanh chn l chnh v -c dng trong sut qu
trnh xe ln bnh.
+ Phanh tay; -c iu khin bng tay, gy lc hm ph trn bnh sau
ch ng hoc hm khu vc gia h thng truyn ng. Phanh tay dng
hm xe dng ti ch v h tr cho phanh chn khi phanh chn b hng.
Theo cu to ca c cu phanh, h thng phanh -c chia thnh;+ C cu phanh guc
+ C cu phanh a
Theo ph-ng thc truyn ng h thng phanh -c chia thnh;+ Dn ng c kh
+ Dn ng thu lc
+ Dn ng kh nn
3.2.3. S cu to v nguyn l lm vic ca phanh guc dn ng c kh.
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a t 1 bt cht ln v bn trc ( bnh sau ) hoc v khp chuyn h-ng (
bnh tr-c ) tang trng phanh 4 bt cht trn moay bnh xe. Gia m
phanh v mt trong ca tang trng phanh c khe h nh. Khi p phanh ccu cam banh ct m phanh lm ct quay quanh cht 3 m phanh p cht
ln mt trong ca tang trng to ra lc hm. Khi nh chn phanh, l xo 6 ko
cht m phanh v v tr ban u lm cho mt ma st tch ri khi mt tang
trng phanh.
3.2.4. H thng phanh truyn ng thu lc ( phanh du)
3.2.4.1.S cu to
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3.2.4.2.Nguyn l lm vic:
Tc dng hm ca phanh l da trn c s lc ma st. Khi ch-a p bn p,
cc guc phanh 10 -c l xo 11 ko nn mt ma sat ( mt ngoi ) ca chng
tch ri khi mt trong ca tang trng 14 nn bnh xe -c quay t do trn
moay .
Nu p chn ln bn p 1, cn 2 s y pt tng 3 ca xi lanh chnh 4
chuyn dch sang phi lm tng p sut du y m van cao p 6 -a du vo-ng ng 7 ti xi lanh cng tc ca cc bnh xe. Lc ydo p sut du
trong cc xi lanh cng tc tng ln to lc y hai pt tng 8 v 9 chy sang hai
bn y guc phanh 10 quay quanh cc cht 13 cc m phanh t p v hm
cht tang trng phanh 14, Lc ma st gia m phanh v tang trng gi khng
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cho cc bnh xe quay tip. Lc y nu bnh xe bm tt mt -ng th lc ma
st trn s to ra m men hm bnh xe dng li.
Ng-i ta dng cc tm aming p, hp cht ca aming vo cao su
hoc si ng v aming lm m phanh dn ln b mt ngoi ca guc phanhnh lm tng lc ma st gia guc v tang trng phanh.
Ma st gia m v tang trng phanh s to ra mt l-ng nhit ln lm
nng tang trng. Khi xe chy khng kh thi qua s gy tc dng lm mt cho
tang trng phanh
Nu nhc chn khi bn p ( nh chn phanh ) th p sut trong hthng du s gim nhanh nh l xo 11, cc guc phanh -c ko li gn nhaulm cho cc pttng 8 v 9 cng b ko vo y du qua van hi du 6 tr v v
xi lanh chnh v b cha, cc m phanh ri khi mt tip xc nn mt trong
ca tang trng khng cn tc dng hm.
3.2.5. Cc ph-ng php b tr guc phanh
S cc loi phanh guc khc nhau v hai mt: lc iu khin phanh ( c kh
hay thu lc ) v im t ca guc khi phanh. Hnh 6.13a -c iu khin
thu lc vi im t l hai cht c nh, khi phanh m phanh ca guc bn
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tri l m cun, lc phanh tng ln nhanh theo h s ma st, cn m guc bn
phi l m nh, lc phanh gim bt khi phanh v vy phanh hnh 6.13 a -c
gi l phanh cun nh iu khin thu lc. Hnh 6.13b l phanh cun nh iu
khn hi hoc c kh, hnh 6.13c phanh mt chiu hai m cun, hnh 6.13e lphanh hai chiu tng lc ( hai m cun ).
3.2.6. Phanh a:
Khc vi c cu phanh tang trng, c cu phanh a, tang trng -c
thay bng mt a thp lp trn may bnh xe. Hai m phanh lp trn gi c
nh trn dm cu kp hai bn a phanh, cc m phanh ny -c dn ng
bi sc p ca pt tng ca xi lanh con p vo a phanh khi ng-i li p
phanh. Kt cu hnh a l s c cu phanh a dng gi xi lanh con di
ng, gi c th di ng theo ph-ng lc p ca pt tng. Do trong c cu
ny ch cn mt xi lanh con. Kt cu hnh b dng gi xi lanh c nh trong
tr-ng hp ny phi dng hai xi lanh con vi hai pt tng p cc m phanh
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hai bn a phanh vo mt a phanh. H thng thu lc dn ng phanh a
cng t-ng t nh- h thng phanh du dn ng c cu phanh tang trng .
C cu phanh a c -u im l lc phanh n nh nn th-ng -c s dng
cho cc phanh bnh xe pha tr-c trn xe du lch. Tuy nhin hin nay xe dulch s dng phanh a cho c bn bnh.
3.2.7. B tr lc phanh chn khng:
Mt s loi xe dng phanh du cn -c trang b thm b tr lc chn
khng vi mc ch s dng chn khng trn -ng ng ht ca ng c
h tr thm vo lc p chn phanh ca ng-i li gip ng-i li tn sc khi
s dng phanh. Hnh 6.16 gii thiu s cu to v nguyn tc ca b tr lc
chn khng. Bung chn khng III -c ni vi -ng ng np ca ng c
qua van 1 chiu, v tr khng s dng phanh ( ng-i li khng p ln chn
phanh) (hnh 6.16a) d-i tc dng ca cc l xo van khng kh 4 ng kn, van
chn khng 5 m, lm cho khng gian II ngn cch vi khng gian I nh-ng li
n thng vi khng gian III. Lc ny chn khng hai khng gian II, III
bng nhau v bng chn khng trn -ng ng ht ca ng c. Do khng
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c chnh p trn hai mt ca mng 3 nn l xo y mng 3 sang tri. khi
ng-i li p chn phanh, du phanh i t xi lanh chnh i ln vi p sut p
y pittng 7 i ln ng van chn khng 5, m van khng kh 4. Lc ny
khng gian II b ngn cch vi khng gian III nh-ng li n thng vi khnggian I. Khng kh t ngoi tri trn vo khng gian II lm tng p sut kh
y, trong khi khng gian III vn tip tc n thng vi chn khng trn
-ng ng np. Nh chnh p hai bn mng 3 b ht sang phi thng qua
thanh y 9 y pittng 8 sang phi, ngoi ra pit tng 8 vn chu tc dng ca
p sut du do xi lanh chnh to ra.
3.2.8. Phanh hi.3.2.8.1. S cu to:
Phanh hi th-ng -c s dng trn t xe c ti trng trung bnh v ln.
c im ca phanh hi l: lc p phanh nh m hiu qu phanh li cao nn
rt d iu khin phanh. V cu to, phanh hi phc tp hn cc loi phanhkhc.
My nn kh 1 chnh l my bm hi do ng c ca xe dn ng. Qua my
nn kh, khng kh -c nn ti p sut do b iu chnh p sut 2 quy nh
ri i vo bnh hi 4 ,dung tch bnh hi m bo d tr hi p phanh mt
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s ln. ng h p sut 5 dng kim tra p sut trong bnh hi. T bnh hi
khng kh nn i vo van iu khin 12. khi ch-a p chn phanh 6 cc np
van trong van iu khin nm v tr ngn khng cho khng kh nn i vo
cc hp phanh 8 v 9, lc y cc hp phanh ny ni thng vi kh tri nn ccbnh xe quay t do khng b phanh.
3.2.8.2. Nguyn l lm vic: Khi p chn phanh 6 cc np van ca tng van 7
thay i v tr lm cc hp phanh 8 v 9 ct t -ng thng vi kh tri v
bt u ni thng vi bnh hi khng kh nn i vo cc hp phanh, y
mng phanh p vo cn lm quay n v cam banh u guc phanh hm
tang trng v bnh xe. nu nh chn khi bn p 6 s ct -ng -a khngkhi nn ti cc hp phanh 8 v 9 v ni cc hp phanh vi kh tri, p sut hi
trong hp phanh gim xung v cc guc phanh tr-t tr v v tr ban u
d-i tc dng ca l xo, nh bnh xe -c nh phanh.
3.2.8.3.Cu to cc b phn trong h thng phanh hi.
a) My nn kh:
+ Cng dng: Dng cung cp khng kh nn cho bnh hi.
Cu to
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+ Nguyn l hot ng: Bnh ai 10 -c lp u trc khuu my nn
-c dn ng t trc khuu ng c nh pittng my nn -c chuyn
ng tnh tin trong xi lanh. Khi pittng i xung to chn khng trong xi
lanh ht m van ht 14 lm cho khng kh ngoi tri -c ht vo sau khi
-c lc sach qua bnh lc kh. Lc pittng i ln, van ht ng kn, khng
kh trong xi lanh b nn y m van y 4v 8 -a khng kh nn qua np xi
lanh n bnh hi.
Khi p sut bnh cha cn nh hn 7 7,5 kg/cm2, th hai van thot ti ng,
khi p sut trong bnh ln hn 7 7,5 kg/cm2, kh nn t van iu chnh p
sut theo ng dn ti c cu bo him y mng 2 i ln, qua n gnh y
m hai van thot ti 5, 6 lm hai xi lanh thng nhau, lc ny kh nn trong hai
xi lanh qua hai van thay i sang nhau m khng np cho bnh cha, trng
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thi ny gi l trng thi khng ti, trng thi ny m bo cho my nn
khng b qu ti nn tui th ca my nn m bo.
Khi p sut ca bnh cha gim xung cn 66,5 kg/cm2 ( do s dng phanh
lm gim l-ng khng kh nn ) van iu chnh p sut ng li l xo ca haivan thot ti 5 v 6 y van ng kn v y n gnh tr v v tr ban u.
My nn kh li tip tc cung cp kh nn cho bnh cha.
b) Tng van phanh:
Khi phanh, van ny c nhim v iu khin p sut t bnh hi ti cc
hp phanh lm cho xe -c hm v gim tc mt cch thch hp. Khi p
chn phanh lm n iu khin tng van i xung p van kh 11 i xung
ng l thot kh ra ngoi ca van 12 v p van 12 i xung M -ng thng
khi t bnh cha kh nn qua -ng 13 sang -ng 15 v n cc bt phanh 8
v 9 cc bnh xe gy ra lc phanh ti cc bnh xe. Khi nh bn p phanh,
van 11 i ln lm van 12 i ln ngt -ng cp kh nn t bnh cha n.Van
11 tip tc i ln lm m -ng thot kh trn van 12 lm kh t cc bt
phanh thot ra ngoi qua l 14. Khi cc l xo hi v ko m phanh v v tr
ban u tch khi tang trng, qu trnh phanh kt thc.
c) B iu chnh p sut
+ Cng dng: B iu chnh p sut l mt cm chi tit c kh dng
iu khin c cu trit p ca my nn kh nhm duy tr p sut nn trong
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bnh cha lun lun nm trong gii hn 0, 6 0,75 MPa khi ng c hot
ng.
+ Cu to:
B iu chnh p sut kiu van bi gm c: thn 9, vng m iu chnh 6, u
ni ren vi l 7 bn s-n, a y 4, l xo 3, ng chp 2 v cc vin bi 11. l xo
3 t ln hai vin bi hai u, y a y 4 v hai vin bi 11 xung bt l
thng vi u ni 10.
C th iu chnh lc p ca l xo bng cch vn chp 2 dc u ni ren
, iu chnh xong dng cu cng hm chp 2. L 8 ni -ng ng thng vi
khng gian iu khin c cu trit p.
+Nguyn tc hot ng: Nu p sut khi nn trong bnh nh hn 0,6
MPa th cc vin bi 11 d-i tc dng ca l xo 3 thng qua a y 4 -c y
xung ng kn l thng vi u ni 10. Lc y l 7 bn s-n u ni ren ni
thng khng gian ca c cu trit p vi kh tri. Nu p st kh nn trong
bnh t 0,7 0,75 MPa th hai vin bi 11 b y ln p l xo 3, lc y l 7 bn
s-n u ni ren 5 -c bt li ct -ng thng vi kh tri ca khng giancha c cu trit p, ng thi ni thng khng gian ny vi bnh hi nh u
ni 10 v qua van 11 lm cho c cu trit p hot ng v my nn kh
ngng cung cp khng khi nn cho bnh hi.
d) Van an ton
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+ Cng dng: Van an aton dng gi cho p sut khi nn trong h
thng khng v-t ln qu cao khi b iu chnh p sut b hng. Van an ton
lp trn np xi lanh ca my nn.
+ Cu to:
gm c thn van 4 ( hnh 6.21 ), mt u ca thn ni vi u ni 6, u khc
lp vt iu chnh 2. Van bi 5 t ln u ni 6, n cng l mt t ca cht kim
tra1. L xo 3 mt u t ln vai ca cht vu t p ln van bi 5 u khc t ln
vt iu chnh 2, xoay vt iu chnh s lm thay i lc p ca l xo 3 ln van
bi 5. iu chnh xong dng cu cn hm vt iu chnh.
+ Nguyn tc hot ng: nu p sut trong h thng v-t qu 0,9 MPath lc do p sut kh nn trong h thng to ra s thng lc l xo 3 nn van bi
b y bt ln x kh nn ra ngoi tri qua l thng 7 ca van.
e) Bnh hi: L mt bnh v thp hnh tr, dung tch mt bnh khong
23 25 lt. Trn xe c hai bnh hi -c bt cht vo hai dm dc hai bn
s-n khung gm xe. Cc bnh hi ( cha kh nn ) u c van x n-c v du
ng d-i y bnh.f) C cu phanh bnh xe:
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gm c guc phanh 19 bn trong tang trng phanh 20. Guc phanh lp tr-t
trong cht 21 sau khi trong l guc phanh p cc bc ng. Cc cht 21
-c bt cht trn gi cu sau. Gia hai u ca hai guc tr-t l cam
phanh 18. l xo 22 ko hai guc phanh li gn nhau, trc ca cam phanh
quay trn ng bc ng lp trn gi . Gi ny cng l ni bt cht hp
phanh bnh xe. Tay n1 7 ca trc cam phanh -c ni vi mng 16 trn
u cht ca hp phanh. V tr ca tay n xung quanh trc cam phanh c th
iu chnh bng vt.
Khng kh nn i vo hp phanh y mng 16 ri thng qua cht y
tay n lm quay trc cam phanh. Khi quay, cam phanh banh u hai trc
guc phanh p hai m phanh t cht vo mt trong ca tang trng phanh.
Nu hnh trnh ca cht hp phanh tng ln nhiu cn phi quay u trc vt
13 iu chnh li gi tr quy nh.
3.2.9. Phanh tay
3.2.9.1. Cng dng: Phanh tay dng
Hm xe dng bnh ti ch. D tr thay phanh chn khi phanh chn b hng
3.2.9.2.. Cu tov nguyn l lm vic ca phanh tay t sau hp s
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a tnh 3 ca phanh -c bt cht vo cc te ca hp s. Trn a tnh
lp hai guc phanh 5 i xng nhau sao cho m phanh gn st mt tang trng
phanh 7, lp trn trc th cp ca hp s. u d-i ca m phanh t ln u
hnh cn ca cht iu chnh 10, u trn t vo mt mt cm banh guc
phanh gm mt cht 4 v hai vin bi cu. Cht banh guc phanh thng qua h
thng tay n -c ni vi tay iu khin 2.
* Nguyn l lm vic
Mun hm xe ch cn ko tay iu khin 2 v pha sau qua h thng tay
n ko cht 4 ra pha sau banh u trn ca guc phanh hm cng trc
truyn ng. V tr hm ca tay iu khin -c kho cht nh c cu con cc
chn vo vnh rng ca b kha. Mun nh phanh tay ch cn n ngn tay
vo nt 1 nh c cu con cc ri y tay iu khin 2 v pha tr-c. L so 8
s ko guc phanh tr li v tr ban u. Vt iu khin 10 dng iu chnh
khe h gia m phanh v tang trng phanh.
3.2.9.2. Cu tov nguyn l lm vic ca phanh tay t ti bnh xe sau;a. Cn phanh tay;
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Cn phanh tay -c ch to vi bnh cc gi cn v tr m n -c t.
Mt s cn phanh tay c vt iu chnh gn cn phanh tay c th d dng
iu chnh hnh trnh chuyn ng ca cn phanh.
b. Cp Phanh tay;Cp phanh tay truyn chuyn ng ca cn n b tang phanh ph. Trong
tr-ng hp phanh tay bnh sau c tm hiu chnh nm gia cp chia u
lc vn hnh ca cn cho c hai bnh, cn trung gian tng lc vn hnh.
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