CHNG I: C S L THUYTBi 1: C s l thuyt v kh nn:

1. Khi nim:

Kh nn l khng kh c nn vi mt p sut cao.

2. Nhng c trng ca kh nn

S lng: Khp mi ni trong khng kh

Vn chuyn: Theo cc ng ng

Lu tr : cc bn, bnh

Nhit : Kh nn t thay i v nhit

Ch chy n: Khng c nguy c chy, nu s dng 6 bar

Sch s: khng c nguy c gy nhim

Trang thit b : R tin

Vt tc: Ln cho php 1-2 m/s hoc 5m/s Tnh iu chnh: u chnh mt cch v cp

Qu ti: Khng xy ra qu ti (Nhn ti cho n khi dng hon ton)

3. Cc c tnh ca kh nn

Tnh cht vt l ca kh nn:

Khng kh khng mu, khng v v khng th nhn thy c

Cc thnh phn ca khng kh:

- 78% nito

- 21% Oxy

4. n v o

4.1. p sut

p sut kh quyn l p sut khng kh ti mc nc bin.

n v o p sut khng kh ti mc nc bin l 760mmHg = 1.013bar.

p sut tng i l p sut cht kh so vi p sut kh quyn (p = 0).

V d: p k ch gi tr 150psi v p sut kh quyn p = 0psi, ta ni p sut tng i l p = 150psi.

p sut tuyt i l p sut cht kh c k n p sut kh quyn (p = 14.5psi).

p sut tuyt i = p sut tng i + p sut kh quyn.

V d: p k ch gi tr 150psi v p sut kh quyn l 14.5psi, ta ni p sut tuyt i l

p = 150 + 14.5 = 164.5psi

4.2. Lc (N) L lc tc ng ln i trng c khi lng 1kg vi gia tc 1m/s2.1N = 1kg. m/s24.3. Cng sut (w) Trong thi gian 1s sinh ra nng lng 1J

1 m lc HP = 745,7w

Bng 1: Bng k hiu

Bng 2: Bng chuyn i gia cc n v o p sut5. Phng trnh trng thi nhit ng hc5.1. nh lut Boyle-Mariotle:

Nhit kh nn khng thay i (T hng s), p sut tuyt i ca kh nn t l nghch vi th tch kh nn.

P x V = C

P1 x V1 = P2 x V2 P: p sut tuyt i(Bar, Kpa)

V: Th tch kh nn(m3)

C: Hng s Nhit kh nn khng thay i (T hng s), p sut tuyt i ca kh nn t l nghch vi th tch kh nn.

V1: (m3) Th tch kh nn ti im P1

V2: (m3) Th tch kh nn ti im P2P1: p sut tuyt i kh nn c th tch V1P2: p sut tuyt i kh nn c th tch V25.2. nh lut Gay-Lussac:

Th tch kh nn khng thay i (V hng s),nhit tuyt i ca khi kh nn thay i t l thun vi p sut kh nn.

5.3. nh lut Charles:

p sut kh nn khng thay i (P=hng s),nhit tuyt i ca khi kh nn thay i t l thun vi th tch kh nn.

5.4. nh lut tng qut

i vi khi lng ca kh nn cho khi c 3 i lng nhit , p sut v th tch thay i.

V d: Mt bnh cha c th tch 0.5m3 cha kh nn vi p sut tng i l 7bar nhit l 400c. Sau khi gim nhit xung cn 200c. Tnh p sut sau cng.

Ta c: V1 = V2 = 0.5m3

T1 = 40 + 273 = 3130k P1 = 7 + 1 = 8bar

T2 = 20 + 273 = 2930k P2 = ? bar

Bi tp p dng:

Bi 1: Mt bnh cha c th tch 2,5 m3 cha kh nn vi p sut tng i l 10 bar nhit l 600c. Sau khi gim th tch xung cn 1,5 m3 .v nhit cn 400c. Tnh p sut sau cng.Bi 2:Mt bnh cha c th tch 1,5 m3 cha kh nn vi p sut tng i l 10 bar nhit l 600c. Sau khi gim p sut xung cn 7,5 bar . V th tch tng ln 2 m3 .Tnh nhit sau cng.Bi 3: Mt bnh cha c th tch 1,5 m3 cha kh nn vi p sut tng i l 10 bar nhit l 600c. Sau khi gim p sut xung cn 7,5 bar v tng nhit ln 800c . Tnh th tch sau cng.Bi 2: C s l thuyt v thy lc

1. Khi nim:

Thy lc c ngha l nc mn hc nghin cu nhng tnh cht v ng dng ca cht lng truyn dn nng lng v iu khin cc hot ng ca my cng tc.

Ta i nghin cu hai lnh vc ca cht lng:

+ Thy tnh hc

+ Thy ng hc2. Cc nh lut ca cht lng

3. p sut thy tnhTrong cht lng, p sut (do trng lng v ngoi lc) tc dng ln mi phn t cht lng khng ph thuc vo hnh dng thng cha.

- khi lng ring ca cht lng; h- chiu cao ca ct nc; g- gia tc trng trng; pS- p sut do lc trng trng; pL- p sut kh quyn;

pF- p sut ca ti trng ngoi;

A, A1, A2- din tch b mt tip xc;

. F- ti trng ngoi. 2. Phng trnh dng chy lin tc

Lu lng (Q) chy trong ng ng t v tr (1) n v tr (2) l khng i (const). Lu lng Q ca cht lng qua mt ct A ca ng bng nhau trong ton ng (iu kin lin tc).

Ta c phng trnh dng chy nh sau: Q = A.v = hng s (const)

Vi v l vn tc chy trung bnh qua mt ct A

Nu tit din chy l hnh trn, ta c:

Q1 = Q2 hay v1.A1 = v2.A2

Trong : Q1[m3/s], v1[m/s], A1[m2], d1[m] ln lt l lu lng dng chy, vn tc dng chy, tit din dng chy v ng knh ng ti v tr 1; Q2[m3/s], v2[m/s], A2[m2], d2[m] ln lt l lu lng dng chy, vn tc dng chy, tit din dng chy v ng knh ng ti v tr 2.

4. Phng trnh BernulliTng nng lng dng chy thy lc s c bo ton nu khng c s thot nng lng ra ngoi , hoc nng lng t bn ngoi tc ng vo h

Tng nng lng bo gm:

+Th nng (sc p ca trng lc) ph thuc vo chiu cao ca ct cht lng v p sut thy tnh

+ng nng (nng lng do chuyn ng) ph thuc vo tc dng chy

C mt dng chy nh hnh v:

5. Cng thy lc

Cng bng tch ca lc vi qung ng i , nh vy cng thy lc tc ng ln pistons nhn vi di hnh trnh dch chuyn.

W = F.S = p.A.S = p.V

Trong

W: cng (j) p: p sut

F: lc (N), P: Cng sut (W) . Q: lu lng

S: di

V: th tch (m3) 6. Tn tht th tch

6.1. Tn tht th tchL do du thy lc chy qua cc khe h trong cc phn t ca h thng gy nn.

Nu p sut cng ln, vn tc cng nh v nht cng nh th tn tht th tch cng ln.

Tn tht th tch ng k nht l cc c cu bin i nng lng (bm du, ng c du, xilanh truyn lc)

i vi bm du: tn tht th tch c th hin bng hiu sut sau:

tb = Q/Q0

Q- Lu lng thc t ca bm du;

Q0- Lu lng danh ngha ca bm.

Nu lu lng chy qua ng c du l Q0 v lu lng thc t Q = q. th hiu sut ca ng c du l:

t = Q0/Q

Nu nh khng k n lng du d cc mi ni, cc van th tn tht trong h thng du p c bm du v ng c du l:

t = tb. t

6.2. Tn tht v c kh

Tn tht c kh l do ma st gia cc chi tit c chuyn ng tng i trong bm du v ng c du gy nn

Tn tht c kh ca bm c biu th bng hiu sut c kh:

cb = N0/N

N0- Cng sut cn thit quay bm (cng sut danh ngha), tc l cng sut cn thit m bo lu lng Q v p sut p ca du, do :

6.3. Tn tht p sut

Tn tht p sut l s gim p sut do lc cn trn ng chuyn ng ca du t bm n c cu chp hnh (ng c u, xilanh truyn lc).

Tn tht ny ph thuc vo cc yu t sau:

+/ Chiu di ng dn +/ nhn thnh ng +/ ln tit din ng dn +/ Tc chy +/ S thay i tit din +/ S thay i hng chuyn ng +/ Trng lng ring, nht

Nu p0 l p sut ca h thng, p1 l p sut ra, th tn tht c biu th bng hiu sut:

P l tr s tn tht AP 7. nht v yu cu nht i vi du thy lc7.1. nht :

nht l mt trong nhng tnh cht quan trng nht ca cht lng. nht xc nh ma st trong bn thn cht lng v th hin kh nng chng bin dng trt hoc bin dng ct ca cht lng. C hai loi nht: a. nht ng lc nht ng lc l lc ma st tnh bng 1N tc ng trn mt n v din tch b mt 1m2 ca hai lp phng song song vi dng chy ca cht lng, cch nhau 1m v c vn tc 1m/s. nht ng lc c tnh bng [Pa.s]. Ngoi ra, ngi ta cn dng n v poaz (Poiseuille), vit tt l P. 1P = 0,1N.s/m2 = 0,010193kG.s/m2

1P = 100cP (centipoiseuilles)

Trong tnh ton k thut thng s quy trn: 1P = 0,0102kG.s/m2b. nht ng nht ng l t s gia h s nht ng lc vi khi lng ring ca cht lng: n v nht ng l [m2/s]. Ngoi ra, ngi ta cn dng n v stc ( Stoke), vit tt l St hoc centistokes, vit tt l cSt. 1St = 1cm2/s = 10-4m2/s

1cSt = 10-2St = 1mm2/s. 7.2. Yu cu i vi du thy lcNhng ch tiu c bn nh gi cht lng cht lng lm vic l nht, kh nng chu nhit, n nh tnh cht ho hc v tnh cht vt l, tnh chng r, tnh n mn cc chi tit cao su, kh nng bi trn, tnh si bt, nhit bt la, nhit ng c Cht lng lm vic phi m bo cc yu cu sau:

+/ C kh nng bi trn tt trong khong thay i ln nhit v p sut;

+/ nht t ph thuc vo nhit ;

+/ C tnh trung ho (tnh tr) vi cc b mt kim loi, hn ch c kh nng xm nhp ca kh, nhng d dng tch kh ra; +/ Phi c nht thch ng vi iu kin chn kht v khe h ca cc chi tit di trt, nhm m bo r du b nht, cng nh tn tht ma st t nht; +/ Du phi t si bt, t bc hi khi lm vic, t ho tan trong nc v khng kh, dn nhit tt, c mun n hi, h s n nhit v khi lng ring nh. Trong nhng yu cu trn, du khong cht tho mn c y nht.

CHNG II: CUNG CP V X L

Bi 1: Cung cp v x l kh nn

1. My nn kh

1.1. My nn kh kiu Piston

a. Nguyn l lm vic:

Khi pistng i xung van np m ra ht khng kh t bn ngoi vo, lc ny van x ng. Khi pis tng i ln van np ng li , kh tip tc c nn n mt p sut nht nh, th van x m ra v kh nn a vo bnh cha, p sut kh nn kiu pis tng n khong 4 bar

b. u v nhc im:

+ u im: Cng vng

Hiu sut cao

Bo qun n gin

+ Nhc im To ting n

Gi thnh bo qun cao

To ra kh nn theo xung v thng c du1.2. My nn kh kiu cnh gt

a. Nguyn l lm vic:

Khng kh c nn vo bung ht, nh rto v stator t lch nhau nn khi r to quay th khng kh s vo bung nn, sau kh nn s vo bung y.

b. u , khuyt im:

+ u im

Khng cng knh

Lm vic m

Sa cha d dng

Lu lng l hng s, kh khng b xung t.

+ Nhc im

Hiu sut nhit km hn my nn kh kiu pis tng

Kh nn thng thng b nhim du.

1.3. My nn kh kiu trc vt

a. My nn kh kiu trc vt:

Hai roto ca trc t song song ( trc 1 c 4 rnh, trc 2 c 6 rnh). Hot ng theo nguyn l thay i th tch, th tch khong trng gia cc rnh s thay i khi trc vt quay c mt vng . S to ra qu trnh ht ( th tch khong trng tng ln) qu trnh nn (th tch khong trng nh li) v cui cng l qu trnh y.

b. u v nhc im:

+ u im

Khng kh sch v khng b xung

Rt tin cy tui th cao 15.000 40.000 gi.

Khng sinh ra giao ng

T s nn b hn ch bi tng

+ Nhc im

Gi thanh cao

Gy ra ting n1.4. My nn kh kiu rt

a. Nguyn l lm vic:

My loi ny gm c 2 hoc 3 cnh (Pistong c dng hnh s 8) cc pistong c quay ng b bng b truyn ng ngoi thn my, trong qu trnh quay khng tip xc nhau. Nh vy kh nng ht ca my ph thuc vo khe h gia 2 pis tng , khe h gia phn quay v thn my .

b. u nhc im

Kh nn to ra t xung v khng b nhim du

t to ra giao ng

mn gia cc rng v xi lanh

2. B lc

2.1. Van lc

Van lc c 3 phn t:

Van lc

Van iu chnh p sut

Van tra du

Van lc c nhim v tch cc phn

t cht bn v hi nc ra khi kh nn( l c th 30 70m hoc 0,01 m

2.2. Van iu chnh p sut

Nhim v ca van p sut n nh p sut iu chnh mc d u ra v u vo lu lng bt thng. 2.3. Van tra du

Van tra du: Nhm cung cp v bi trn cho thit b trong h thng iu khin kh nn nhm gim ma st, s n mm v g st. 3. Thit b x l kh nn3.1. Yu cu v kh nn

Kh nn c to ra t nhng my nn kh khc nhau, trong kh nn cha rt nhiu bi, m

Trong qu trnh nn t0 kh nn tng ln c th gy nn xy ha mt s phn t k trn.

Chnh v vy kh nn s dng trong cng nghip phi qua x l, ty thuc vo phng php x l v phm vi ng dng ca tng thit b.3.2. Cc phng php x l kh nn

a. S dng bnh ngng t lm lnh bng khng kh.

Kh nn sau khi ra khi my nn kh s c y vo bnh ngng t, ti y p sut kh s c lm lnh, phn ln hi nc cha trong khng kh s c ngng t v tch ra.

H thng dn nc lm lnh

Nc lm lnh c dn vo

Kh nn sau khi c lm lnh

Tch nc sau khi lm lnh

Nc lm lnh i ra

Kh nn c dn vo t my nn kh.

b. Thit b xy kh bng cht lm lnhKh nn t my nn kh s qua b phn trao i nhit kh (1) >b phn trao i nhit kh - cht lm lnh (2) ti y dng kh nn s c i chiu trong nhng ng dn nm trong cc thit b ny( T0 ha sng y l 20c hi nc s b kt ta ti (3)

Du, nc v cht bn sau khi c tch ra khi dng kh nn s4 c i ra ngoi qua (4) > dng kh c lm sch vn cn lnh s c a n b phn trao i nhit (1) ti T0 t 6 80c trc khi a vo s dng.Bi 2: Cung cp v x l du

1. B du

1.1. Nhim v: Cung cp du cho h thng lm vic theo chu trnh kn

Gii ta nhit sinh ra trong qu trnh bm du lm vic

Lng ng cc cn gi, bn trong qu trnh lm vic

Tch nc.1.2. Chn kch thc b du

i vi b du di ng th tch b du ta chn nh sau:

V = 1,5qv

i vi b du c nh th tch b du ta chn nh sau:

V = (0,3 0,5)qv

Trong :

V : lt

qv: lt/pht1.3. Kt cu b du

2. B lc du

2.1. Nhim v Ngn chn nhng cht bn trong qu trnh lm vic.

t u ng ht ca bm du, v ca ra

2.2. Phn loi theo kch thc lc.

Ty thuc vo yu cu s dng m ta c ta chn b lc c kch c khc nhau.

B lc th: C l lc 0,1mm B lc trung bnh: C l lc 0,01mm B lc tinh: C l lc 0,005mm3. Bm v ng c du3.1. Khi nim:Bm v ng c du l hai thit b c chc nng khc nhau.

Bm l phn t to ra nng lng

ng c du l thit b tiu hao nng lng.

Nhng tnh ton v kt cu ca hai loi ny ging nhau.3.2. Bm bnh rng

a. Nguyn l lm vic:

Theo nguyn l thay i th tch. Khi V bung ht tng bm ht du thc hin k ht A, Khi V gim bm dy du ra ca B thc hin k nn

Nu trn ng i ta t mt vt cn th du s b chn li to nn mt p sut nht nh ph thuc vo ln ca vt cn v kt cu ca bm. b. Lu lng bm bnh rng c tnh theo cng thc:

Trong : m: m un ca bnh rng ( cm)

d: ng knh vng chia

b: b rng bnh rng

n: s vng quay trong mt pht

z: s rng

v : hiu sut th tch3.3. Bm trc vt

a. Bm cnh gt dng rng ri hn bm bnh rng v:

+ n nh lu lng

+ Hiu sut v

th tch caob. Lu lng c tnh theo cng thc

Trong :

ng knh Stato

chiu rng cnh gt

lch tm

s vng quay ca roto

3.4. Bm piston

Bm piston c s dng rng ri trong h thng thy lc, lm vic p sut cao

Lu lng c tnh theo cng thc:

d: ng knh piston

h: khong chy piston h = 2e = (1.3 1.4)d

e: lch tm

i: s piston

. n: s vng quay ca rto

3.5. Bm hng trc

4. Tiu chun chn bm

Chn bm cn phi cn c vo yu cu k thut v knh t

Gi thnh tui th, p sut, phm vi s vng quay, kh nng chu hp cht ha hc, s dao ng ca lu lng , cng sut , hiu sut

CHNG III: CC PHN T TRONG H THNGBi 1: Cc phn t kh nn

1. Khi nim

H thng iu khin : Gm cc cm v phn t chnh, c chc nng sau:

a. C cu to nng lng: bm du, b lc (...)

b. Phn t nhn tn hiu: cc loi nt n (...)

c. Phn t x l: van p sut, van iu khin t xa (...)

d. Phn t iu khin: van o chiu (...)

e. C cu chp hnh: xilanh, ng c du.

2. Van p sut

2.1. Nhim v Van p sut dng iu chnh p sut, tc l c nh hoc tng, gim tr s p trong h thng iu khin bng thy lc.

2.2. Phn loi:Van p sut gm c cc loi sau:

2.2.1. Van trn v van an ton Van trn v van an ton dng hn ch vic tng p sut cht lng trong h thng thy lc vt qu tr s quy nh. Van trn lm vic thng xuyn, cn van an ton lm vic khi qu ti. K hiu ca van trn v van an ton:

C nhiu loi:

+ Kiu van bi (tr, cu)

+ Kiu con trt (pittng)

+ Van iu chnh hai cp p sut (phi hp)

2.2.2. Van gim pTrong nhiu trng hp h thng thy lc mt bm du phi cung cp nng lng cho nhiu c cu chp hnh c p sut khc nhau. Lc ny ta phi cho bm lm vic vi p sut ln nht v dng van gim p t trc c cu chp hnh nhm gim p sut n mt gi tr cn thit.

K hiu: 2.2.3. Van cn Van cn c nhim v to nn mt sc cn trong h thng > h thng lun c du bi trn, bo qun thit b, thit b lm vic m, gim va p.

3. Van o chiu3.1. Van o chiu 2/2

3.2. Van o chiu 3/2

3.3. Van o chiu 3/2 tc ng bng c chn 2 chiu

3.4. Van o chiu 5/2

3.5. Van logic OR

3.6. Van logic AND

4. Van tit lu

5. C cu chp hnh

5.1. Xy lanh tc ng mt pha

5.2. Xy lanh tc ng 2 pha

CHNG IV:CC PHN T IN

1. Cng tc

2. Nt nhn

2.1. Nt nhn thng h

2.2. Nt nhn thng ng

3. Cc phn t c bn khc3.1. Cng tc hnh trnh

3.2. Cm bin

4. Cc k hiu phn t iu khin th hin trong qu trnh thit k m phng

5. Gii thiu mt s phng php thit k mch iu khin

5.1. S trng thi

5.2. Nguyn tc chia tng

Trong mt tng mt xy lanh khng thay i trng thi 2 ln.

5.2.1. Mch chun 2 tng

5.2.2. Mch chun 3 tng

5.2.3. Mch chun 4 tng

5.2.4. Mch chun n tng

5.3. Phng php thit k tun t

CHNG V: MT S NG DNG

1. Nhn nt nhn xy lanh A i ra, chm cng tc hnh trnh xy lanh i vo

1.1. iu khin kh nn

1.2. iU khin in kh nn

2. Thit k mch iu khin, nhn Start xy lanh A i ra, chm cng tc hnh trnh S1 xy lanh B i ra, chm cng tc hnh trnh S2, c hai xy lanh i v

3. Nhn nt Start xy lanh thy lc ( kh nn) i ra, nhn Stop quay v ( s dng van 4/3 hoc van 5/3 t gi tc ng 2 pha)

4. Mch iu khin 2 xy lanh s dng phng php iu khin theo tng

Nguyn l hot ng:

..

5. Mch iu khin 3 tng:

Nguyn l hot ng:

..

6. Mch iu khin 1 xy lanh s dng cm bin nhn tn hiu gii hn hnh trnh

Nguyn l hot ng:

..