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Katedra za motore i vozila MOTORNA VOZILA 2012 – 2013 Krunoslav Ormuž, Goran Šagi, Ante Šoda

Motorna vozila FSB

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Katedra za motore i vozila

MOTORNA VOZILA2012 2013 Krunoslav Ormu, Goran agi, Ante oda

Katedra za motore i vozila

A) TEORIJA MOTORNIH VOZILA MEHANIKA VONJE (STATIKA / KINEMATIKA / DINAMIKA)A.1 POGON VOZILA A.2 VUNE KARAKTERISTIKE A.3 OSNOVE TEORIJE KOENJA A.4 STABILNOST VOZILA A.5 UPRAVLJANJE AUTOMOBILOM

B) KONSTRUKCIJA VOZILAB.1 KONSTRUKCIJSKE OSOBINE POJEDINIH TIPOVA VOZILA B.2 GLAVNI SKLOPOVI VOZILA

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Katedra za motore i vozila

A.2 VUNE KARAKTERISTIKESkup svojstava koja su vana za obavljanje funkcije vozila u cijelom podruju predvienih brzina vonje: vune sile (savladavanje otpora vonje), ubrzanje / usporenje, vrijeme potrebno za postizanje odr. brzine, put potreban za postizanje odr. brzine. Tijekom izrade prorauna vunih karakteristika mogu se, u nedostatku odgovarajuih iskustvenih vrijednosti, provjeriti zamisli kako poboljati svojstva vozila (npr. prijenosne omjere u prijenosniku snage).

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Katedra za motore i vozila

A.2 VUNE KARAKTERISTIKEVune karakteristike motornog vozila ovise o pogonskom stroju. Motor mora savladati otpore vonje, koji ovise o konstrukciji vozila i uvjetima eksploatacije.PMax. pogonska snaga

vMax. snaga koenja Max. broj okretaja motora (pri P < 0)

Max. brzina vozila Vmax

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Katedra za motore i vozila

A.2 VUNE KARAKTERISTIKEA.2.1 A.2.2 A.2.3 A.2.4 A.2.5 Karakteristike pogonskih strojeva Bilanca otpora vonje i vunih sila Bilanca snage Performanse vozila Utjecaj konstrukcijskih parametara na performanse

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Katedra za motore i vozila

A.2.1 POGONSKI STROJEVI MOTORNIH VOZILAVrste pogona: MSUI (klipni motori, plinska turbina, parna turbina), Elektrini pogon (baterije, gorive elije, solarna energija)

Studebaker Indy 500 (1967)

Volvo ECC (1992) Mercedes A-Klasse (1998)

Toyota Prius (2004)

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Katedra za motore i vozila

A.2.1 KARAKTERISTIKE POGONSKIH STROJEVA

Jankovi (2001)

DIESEL MOTOR S REGULATOROM

OTTO MOTOR

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Katedra za motore i vozila

A.2.1 KARAKTERISTIKE POGONSKIH STROJEVA

PARNI KLIPNI STROJ PLINSKA TURBINA

Jankovi (2001)ELEKTROMOTOR IZMJENINE STRUJE

ELEKTROMOTOR ISTOSMJERNE STRUJE

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Katedra za motore i vozila

A.2.1 POGONSKO GORIVO MOTORNIH VOZILAVrste pogonskih goriva: tekua goriva (benzin, diesel, bio-diesel, ukapljeni plin, alkohol ), plinovita goriva (vodik, para), kruta goriva elektrine baterije, solarna energija.BMW Hydrogen 7 (2007)

TU Delft Nuna 3 (2005) Stanley Steamer (1903)

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Katedra za motore i vozila

A.2.1 KLIPNI MSUI: BENZIN & DIESELMSUI Diesel+ + + manja potronja vei termiki stupanj iskoristivosti vei okretni moment aavi ispuh velika teina skuplje odravanje + + + +

Benzinski (Otto)brzohodniji vea specifina snaga jeftinija tehnologija manje ovise o klimatskim uvjetima vea specifina potronja skuplje gorivo?

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Katedra za motore i vozila

A.2.1 KLIPNI MSUI: BENZIN & DIESELKarakteristike MSUI klipnih pogonskih strojeva na tekue gorivo: Tekue gorivo s velikim specifinim kapacitetom energijeBenzin: 43 MJ/kg ili 35 MJ/l Diesel: 45 MJ/kg ili 39 MJ/l Li-baterije: 0.5 1 MJ/kg ili 1 2 MJ/l Kompr. vodik: 142 MJ/kg ili 4.7 MJ/l CNG: 36 50 MJ/kg Atomsko gorivo (fuzija): 3.0e+08 MJ/kg

Niska specifina potronjaBenzin: 0.30 kg/kWh Diesel: 0.20 0.25 kg/kWh Plinska turbina: 0.50 kg/kWh

Relativno niska specifina masaBenzin: 0.5 1 kg/kW Diesel: 2 50 kg/kW Elektromotor: 0.75 kg/kW Space shuttle: 0.005 kg/kW

http://www.motorlexikon.de/?I=9502

F1 2007- V8 2.4 l Otto: 0.15 kg/kW Audi R10 Le Mans 2006- V12 5.5 l TDI : 0.40 kg/kW

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Katedra za motore i vozila

A.2.1 KLIPNI MSUI: BENZIN & DIESELKarakteristike MSUI pogonskih strojeva: Velika specifina snaga u odnosu na volumenBenzin: 50 230 kW/l Diesel: 35 90 kW/lF1 2007: V8, 2.4 l, 550/750 kW/KS pri 19 000 min-1, m = 95 kg Audi R10 TDI Le Mans 2006: V12, 5.5 l, 485/650 kW/KS pri 5 000 min-1, m > 200 kg

Nizak stupanj iskoristivostiBenzin: 0.25 0.30 Diesel: < 0.40 Elektromotor + baterije: 0.75

http://en.wikipedia.org/wiki/Audi_R10

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Katedra za motore i vozila

A.2.1 KLIPNI MSUI: PERFORMANSEBrzinske karakteristike MSUI pogonskih strojeva: promjena snage (P), okretnog momenta (M) i specifine potronje goriva (ge) prilikom promjene brzine vrtnje (n) motora, za odreeni stupanj optereenja (reim ubrizgavanja goriva ili poloaj leptira karburatora).P, M, geP = f (n)

Ako se radi o najveem punjenju motora (100 % optereenje) Vanjska brzinska karakteristika.

M = f (n)

ge = f (n)

n13

Katedra za motore i vozila

A.2.1 KLIPNI MSUI: PERFORMANSEMotori rijetko rade u reimu najveeg punjenja Najvie vremena rade pod djelominim optereenjem Parcijalne brzinske karakteristike. Specifina potronja goriva, ge [kg/kWh] ovisi o opterecenju motora i brzini vrtnje motora.ge100% optereenja

75 % opt.

50 % opt.

n Toke ne gornjoj krivulji skinute su s gornjeg ruba podruja rada motora (lijevo). Dakle, dijagram koji se odnosi na 100% optereenja daje vrlo povrnu sliku o motoru.

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Katedra za motore i vozila

A.2.1 KLIPNI MSUI: PERFORMANSEPri vonji u odreenom stupnju mjenjaa vrijedi: apsolutna potronja goriva po kilometru [kg/km] opada smanjenjem brzine voznje.

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1

Potronja goriva, l/100 km

VW Golf 4, TDI, 1998., 66 kW uspon 0%, protuvjetar 0 m/s

15

510

2

3

4

5

0 0 50 100 150 200

Brzina, km/h

Primjer za kamionski motor

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Katedra za motore i vozila

A.2.1 KLIPNI MSUI: PERFORMANSEBrzinska karakteristika motora pri punom optereenju:P, M, ge3 4 5 6

Karakteristine toke:

P

1 Najmanja brzina vrtnje pri kojoj motor mirno radi bez optereenja (prazni hod), 2 Brzina vrtnje pri kojoj je motor spreman podnijeti optereenje, 3 Brzina vrtnje pri najveem momentu, 4 Brzina vrtnje pri najnioj specifinoj potronji, 5 Brzina vrtnje pri kojoj motor razvija najveu snagu, 6 Najvea brzina vrtnje pri kojoj motor radi bez opasnosti od oteenja.1 2

M

ge

nmin nP min

nM max nge min

nmax

n

nP max

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Katedra za motore i vozila

A.2.1 KLIPNI MSUI: ELASTINOSTP, MPmax Mmax MP max

Elastian motor

P, MPmax Mmax MP max

Krut motor

nM max

nP max

n

nM max nP max

n

Faktor elastinosti obzirom na zakretni moment:eM = M max M P maxnP max nM maxOtto: 1.15 1.35 Diesel: 1.05 1.20

Faktor elastinosti obzirom na broj okretaja:en =Otto: 1.80 2.20 Diesel: 1.30 1.6017

Katedra za motore i vozila

A.2 VUNE KARAKTERISTIKEA.2.1 A.2.2 A.2.3 A.2.4 A.2.5 Karakteristike pogonskih strojeva Bilanca otpora vonje i vunih sila Bilanca snage Performanse vozila Utjecaj konstrukcijskih parametara na performanse

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Katedra za motore i vozila

A.2.2 IDEALNA VUNA SILABilanca (ravnotea) vune sile i otpora vonje dana je jednadbom vune ravnotee: FV = Rkot. + Rzraka Rpenj. Rubrz. Idealna vuna sila, tj. vuna karakteristika za sluaj konstantne maksimalne snage: FV, id = Pe, max / (vmax )n = const. / (vmax )nFv, id ... Idealna vuna sila pri zadanom broju okretaja

F

Pe, max ... Maksimalna efektivna snaga motora (vmax )n ... Maksimalna brzina vozila pri zadanom broju okretaja

v

Idealna vuna sila prikazana u F, v - dijagramu zove se hiperbola vue.19

Katedra za motore i vozila

A.2.2 VUNA SILA NA KOTAUVuna sila dovedena pogonskom kotau:FV = M P M m i uk t = rd rd

Jednadba vune ravnotee :

M m iuk t 1 1 2 = f k mv g cos + v A C D mv g sin mv + 2 I k + I m (iuk ) 2 rd 2 rd

(

)

a

Rk

RzFV ... Mp ... Mm ... iuk = iN i0 ...

Rp

Ru

Vuna sila prenesena na podlogu [N] Moment doveden pog. kotau [Nm] Moment motora [Nm] Ukupni prijenosni omjer Ukupna iskoristivost transmisije Dinamiki radijus kotaa [m] 20

Izraun ove ravnotee za proizvoljnu brzinu vozila daje vuni dijagram.

t ...rd ...

Katedra za motore i vozila

A.2.2 RAVNOTEA OTPORA I VUNE SILEBrzina kretanja je jedno od osnovnih mjerila funkcionalne sposobnosti vozila Performanse vozila analiziraju se kao funkcija ovisnosti o brzini.MDijagram okretnog momenta motora: Dijagram vune sile:

FV RFV = f (v)

M = f (n)

100% opt.

n

vmaxM n FV ... v ... R

v

Vuni dijagram Grafika interpretacija vune ravnotee vunih sila i sila otpora, za sve mogue brzine kretanja vozila.

Okretni moment motora [Nm] Brzina vrtnje motora [1/min] Vuna sila prenesena na podlogu [N] Brzina kretanja vozila [m/s] Ukupni otpori vonje [N]

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Katedra za motore i vozila

A.2.2 VIAK VUNE SILEKad je vozilo na usponu otpori vonje rastu: Savladavanje uspona + mogunost ubrzanja izmeu motora i pogonskih kotaa potrebno ugraditi transmisijski element mjenja. FV(FV )I (FV )II (FV )III (FV )IV (FV )VR (s=30%) R (s=20%) R (s=10%) R (s=0%)

vim = n1 z 2 z 4 = >1 n2 z 1 z 3

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Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAEWhat is a transmission? The transmission is a device that is connected to the back of the engine and sends the power from the engine to the drive wheels. An automobile engine runs at its best at a certain RPM (Revolutions Per Minute) range and it is the transmission's job to make sure that the power is delivered to the wheels while keeping the engine within that range. It does this through various gear combinations. In first gear, the engine turns much faster in relation to the drive wheels, while in high gear the engine is loafing even though the vehicle may be travelling at high speed.5-speed gearbox + reverse, the 1600 VW Golf (2009) Tractor transmission with 16 forward and 8 backward gears Shimano XT (3 x 5) mountain bike

http://en.wikipedia.org/wiki/Transmission_(mechanics)

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAEVei broj parova zupanika vea mogunost redukcije mogue savladati vee uspone te ostvariti bolja ubrzanja.

im =

n1 z 2 z 4 = >1 n2 z 1 z 3

Najvea ostvariva vuna sila ograniena je graninom adhezivnom silom:

FV , max a GaFV = FT ... Sila trenja na mjestu kontakta kotaa i podloge (ovo nije otpor kotrljanja!) [N]

a ...Ga ...

Adhezivni koeficijent trenja [-] Optereenje kotaa na pogonskoj osovini ili adhezivno optereenje [N] 24

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAEPrijenosni odnosi u mjenjau izlazne karakteristike motora pribliavaju se idealnoj vunoj karakteristici (hiperboli). Tendencija k veem broju prijenosa nedostatak: mjenjai postaju kompleksni!

FV

I II III IV V FV = const.

vSix-speed manual transmission for a rear-drive car (General Motors).http://www.answers.com/

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Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAEOn a rear wheel drive car the transmission is usually mounted to the back of the engine. A drive shaft connects the rear of the transmission to the final drive which is located in the rear axle and is used to send power to the rear wheels. On a front wheel drive car the transmission is usually combined with the final drive to form what is called a transaxle. The engine on a front wheel drive car is usually mounted sideways in the car with the transaxle tucked under it on the side of the engine facing the rear of the car. Front axles are connected directly to the transaxle and provide power to the front wheels.

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAEThere are a number of other arrangements but the two systems described above are the most popular.

Original Mini (1959)

Panhard (1895)

http://en.wikipedia.org/wiki/Automobile_layout

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAEFront wheel drive Rear wheel drive Four wheel drive

http://en.wikipedia.org/wiki/Automobile_layout

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAESome sports cars use the rear drive arrangement with transmission mounted directly to the final drive at the rear (transaxle) and connected by a drive shaft to the torque converter which is still mounted on the engine. This system balances the weight evenly between the front and rear wheels for improved performance and handling.

www.ferrari.it

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAEThe first four-wheel drive car, as well as hill-climb racer, with internal combustion engine, the Spyker 60 H.P., was presented in 1903 by Dutch brothers Jacobus and Hendrik-Jan Spijker of Amsterdam. The two-seat sports car, which was also the first ever car equipped with a six-cylinder engine, is now an exhibit in the Louwman Collection (the former Nationaal Automobiel Museum) at the Hague in The Netherlands.http://en.wikipedia.org/wiki/Four-wheel_drive

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAECompetition brings out the best in people, like Volkswagen engineers from the early 1980s tired of the Audi Quattro hogging the spotlight. Their answer? The Bimotor Scirocco: two 1.7-liter engines, 360 hp and a 0 - 60 ride in 4 seconds. VW eventually produced just two working models of the twin-engine hatchback, one with custom race engines, the other with a more production-ready setup offering 282 hp. Each engine had its own transmission and drove its closest axle independently.

http://www.rodosnightlife.com/en2/news/x-cars-motors/dual-engined-bimotor-scirocco-volkswagen-never-was

Katedra za motore i vozila

A.2.2 PRENOENJE SNAGE NA KOTAE

http://www.drivingfast.net/track/engine-driveline.htm#axzz1bPHDy5q6

Katedra za motore i vozila

A.2.2 VRSTE PRIJENOSA SNAGETransmisson types(www.wikipedia.org)

Manual

Nonsynchronous

Automatic

Semi-automatic

Continuouslyvariable

Bicycle gearing

H-type Sequential(performance cars & motorcycles)

Agricultural &military application

Full-Auto Tiptronic(Porsche)

Hydraulic / electronic(Alfa Selespeed, BMW SMG) Twin-clutch (VW DSG) Saxomat

Variomatic Multi-tronic Lineartronic

Derailleurgears Hub gears

ZF Friedrichshafen AG and BMW introduced the first six-speed (the ZF 6HP26 in the 2002 BMW E65 7-Series). Mercedes-Benz's 7G-Tronic was the first seven-speed in 2003, with Toyota introducing an 8-speed in 2007 on the Lexus LS 460.

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Katedra za motore i vozila

A.2.2 AUTOMATSKI MJENJAIAn automatic transmission (automatic gearbox) is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually. Similar but larger devices are also used for heavy-duty commercial and industrial vehicles and equipment. Some machines with limited speed ranges or fixed engine speeds, such as some forklifts and lawn mowers, only use a torque converter to provide a variable gearing of the engine to the wheels.

http://www.swapmeetdave.com/Humor/Workshop/Safety.htm

34

Katedra za motore i vozila

A.2.2 AUTOMATSKI MJENJAIThe modern automatic transmission is by far, the most complicated mechanical component in today's automobile. Automatic transmissions contain mechanical systems, hydraulic systems, electrical systems and computer controls, all working together in perfect harmony. An automatic uses a torque converter instead of clutch to manage the connection between the transmission gearing and the engine. The converter allows the engine to continue running when the vehicle stops. The principle behind a torque converter is like taking a fan that is blowing air into another fan which is unplugged. If you grab the blade on the unplugged fan, you are able to hold it from turning but as soon as you let go, it will begin to speed up until it comes close to the speed of the powered fan. The difference with a torque converter is that instead of using air, it uses oil (transmission fluid).35

Katedra za motore i vozila

A.2.2 AUTOMATSKI MJENJAIA torque converter is a doughnut shaped device that is mounted between the engine and the transmission. It consists of three internal elements that work together to transmit power to the transmission: Pump, Turbine, Stator. The pump is mounted directly to the converter housing which in turn is bolted directly to the engine's crankshaft and turns at engine speed. The turbine is inside the housing and is connected directly to the input shaft of the transmission providing power to move the vehicle. The stator is mounted to Torque converter internal one-way clutch so that it can spin freely in one direction but not in the other.36

Katedra za motore i vozila

A.2.2 MJENJAI S DVIJE SPOJKEThe twin-clutch transmission, also known as the Direct Shift Gearbox (DSG) or dual-clutch transmission, is an automated transmission that can change gears faster than any other geared transmission. Twin-clutch transmissions deliver more power and better control than a traditional automatic transmission and faster performance than a manual transmission. Originally marketed by Volkswagen as the DSG and Audi as the S-Tronic, twin-clutch transmissions are now being offered by several automakers, including: - Complete VW Group, - Nissan, - Mitsubishi, - BMW, - Porsche, - Ferrari.koda DSG Ferrari FF (2010)

http://cars.about.com/od/thingsyouneedtoknow/a/ag_howDSGworks.htm

37

Katedra za motore i vozila

A.2.2 MJENJAI S DVIJE SPOJKEBefore DSG: The SMT The DSG is a development of the sequential manual transmission (SMT), a fully-automated manual transmission with a computer-controlled clutch. The advantage of an SMT is that it uses a solid coupling (the clutch), which provides a direct connection between engine and transmission and allows 100% of the engine's power to be transmitted to the wheels. Traditional automatics use a fluid coupling (torque conv.), which allows some slippage. The chief drawback of the SMT is the same as that of a manual: In order to change gears, the engine and transmission must be disconnected, interrupting the flow of power.http://www.newtechland.com.tw http://cars.about.com/od/thingsyouneedtoknow/a/ag_howDSGworks.htm

BMW E46 M3 SMG (2001)

38

Katedra za motore i vozila

A.2.2 MJENJAI S DVIJE SPOJKEThe twin-clutch transmission was designed to eliminate the lag inherent in SMTs and manuals. The twin-clutch transmission is essentially two separate transmissions with a pair of clutches between them. One transmission (or gearbox) provides odd-numbered speeds (gears 1, 3 and 5), the other provides even-numbered speeds (2, 4, 6).

http://cars.about.com/od/thingsyouneedtoknow/a/ag_howDSGworks.htm

39

Katedra za motore i vozila

A.2.2 MJENJAI S DVIJE SPOJKEWhen the car starts out, the "odd" gearbox is in first gear and the "even" gearbox is in second gear. The clutch engages the odd gearbox and the car starts out in first gear. When it's time to change gears, the transmission simply uses the clutches to switch from the odd gearbox to the even gearbox, for a near-instant change to second gear. The odd gearbox immediately pre-selects third gear. At the next change the transmission swaps gearboxes again, engaging third gear, and the even gearbox pre-selects fourth gear.M: Motor A: Primary drive B: Double Clutch C: shaft D: main shaft, even gears E: main shaft, odd gears F: Output

http://en.wikipedia.org/wiki/Direct-Shift_Gearbox

40

Katedra za motore i vozila

A.2.2 MJENJAI S DVIJE SPOJKEAdvantages of the twin-clutch/DSG transmission:

The primary advantage of the twin-clutch/DSG is that it provides thesame driving characteristics of a manual transmission (i.e. quicker throttle response and no drop in engine speed when the driver lifts off the accelerator) with the convenience of an automatic.

The ability to perform near-instantaneous gearshifts gives the twinclutch advantages over both manuals and SMTs. Volkswagen's DSG takes about 8 milliseconds to upshift. Compare that to the SMT in the Ferrari Enzo, which takes 150 ms to upshift.

Better fuel economy (up to 15% improvement) than conventionalplanetary geared automatic transmission and, for some models, also better than manual transmission.

http://cars.about.com/od/thingsyouneedtoknow/a/ag_howDSGworks.htm

41

Katedra za motore i vozila

A.2.2 MJENJAI S DVIJE SPOJKEDisadvantages of the twin-clutch transmission:

The main limitation of the twin-clutch/DSG is the same as all gearedtransmissions - because there are a fixed number of gears the transmission cannot always keep the engine at its best speed for maximum power or maximum fuel economy.

Marginally worse overall mechanical efficiency compared to aconventional manual transmission, especially on wet-clutch variants.

Expensive specialist transmission fluids/lubricants with dedicatedadditives are required, which need regular changes.

Relatively expensive to manufacture, and therefore increases newvehicle purchase price.

The twin-clutch transmission's computerized controller calculates thenext likely gearchange based on speed and driver behavoior and has the "idle" gearbox pre-select that gear. Relatively lengthy shift time is required when shifting to a gear ratio which the transmission ECU did not anticipate (around 1100 ms, depending on the situation).http://cars.about.com/od/thingsyouneedtoknow/a/ag_howDSGworks.htm

42

Katedra za motore i vozila

A.2.2 MJENJAI S DVIJE SPOJKEIm Jahr 1939 meldete der franzsische Erfinder Adolphe Kgresse und 1940 der Darmstdter Professor Rudolf Franke erste Patente fr eine Art Doppelkupplungsgetriebe an. Die ersten Studien zum PDK gingen auf das Jahr 1969 bei Porsche zurck. Daraus ergab sich das Porsche-Getriebe PDK (Porsche Doppelkupplungsgetriebe) Typ 919, das aber aufgrund zu ruppiger Schaltvorgnge nicht in die Serienfertigung gelangte. Im Zuge der Entwicklung des Porsche 956/962 (1984 1991) wurde das PDK wieder aktuell und mehrfach von Porsche im Rennsport eingesetzt.

http://de.wikipedia.org/wiki/Doppelkupplungsgetriebe

43

Katedra za motore i vozila

A.2.2 MJENJAI S KONT. PROMJENOM PRIJENOSNIH ODNOSAIn the early days of automotive technology, the engine's power was low and a simple solution could be applied: a friction variator (today named CVT for Continuously Variable Transmission) by means of a flat disc driving a wheel at right angle. By sliding the wheel on its shaft, it was possible to vary gradually the transmission ratio, either in forward motion or in reverse. A neutral was obtained by pulling back the plate on its shaft to interrupt its contact with the wheel. It was used in particular in the USA by Carter, Lambert and Metz, in England by GFK and in Switzerland by Turicum during the years 1906 1920. It was not an automatic system because its regulation was entrusted to the driver.http://www.histomobile.com/dvd_histomobile/usa/tech/83-2.htm

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Katedra za motore i vozila

A.2.2 MJENJAI S KONT. PROMJENOM PRIJENOSNIH ODNOSAThough there are several types of CVTs, most cars use a pair of variable-diameter pulleys, each shaped like a pair of opposing cones, with a metal belt or chain running between them. One pulley is connected to the engine (input shaft), the other to the drive wheels (output shaft). The halves of each pulley are moveable; as the pulley halves come closer together the belt is forced to ride higher on the pulley, effectively making the pulley's diameter larger. Changing the diameter of the pulleys varies the transmission's ratio. Making the input pulley smaller and the output pulley larger gives a low ratio for better low-speed acceleration. As the car accelerates, the pulleys vary their diameter to lower the engine speed as car speed rises. http://cars.about.com/od/thingsyouneedtoknow/a/CVT.htmhttp://drive2.subaru.com/Sum09/Sum09_whatmakes.htm

45

Katedra za motore i vozila

A.2.2 MJENJAI S KONT. PROMJENOM PRIJENOSNIH ODNOSAAdvantages of the CVT The CVT can vary the engine speed as needed to access maximum power as well as maximum fuel efficiency. This allows the CVT to provide quicker acceleration than a conventional automatic or manual transmission while delivering superior fuel economy. Disadvantages of the CVT The CVT's biggest problem has been user acceptance. Because the CVT allows the engine to rev at any speed, the noises coming from under the hood sound odd to ears accustomed to conventional manual and automatic transmissions. The gradual changes in engine note sound like a sliding transmission or a slipping clutch - signs of trouble with a conventional transmission, but perfectly normal for a CVT. Because early automotive CVTs were limited as to how much horsepower they could handle, there has been some concern about the long-term reliability of the CVT. Advanced technology has made the CVT much more robust. Nissan has more than a million CVTs in service around the world and uses them in powerful cars such as the 290 horsepower Maxima, and says their long-term reliability is comparable to conventional transmissions.http://cars.about.com/od/thingsyouneedtoknow/a/CVT.htm

46

Katedra za motore i vozila

A.2.2 MJENJAI S KONT. PROMJENOM PRIJENOSNIH ODNOSAIn the late sixties DAF wanted to get rid of their plain image and prove the capabilities of their Variomatic CVT transmissions. In 1967 DAF entered two cars in F3, Cosworth engines were used, tuned for top-end power because the CVT system took care of the necessary flexibility.

The blue car seen behind the DAF F3 is the 1993 Williams FW15C CVT prototype. This car was used by the Williams F1 team to test the feasibility of a CVT transmission in Formula 1. The FIA, the governing body of Formula 1, banned all CVT transmissions from single-seater racing in 1994.http://www.ritzsite.demon.nl/DAF/DAF_cars_p17.htm

47

Katedra za motore i vozila

A.2.2 KONSTRUIRANJE VUNOG DIJAGRAMAZa izraun pogonske sile na kotau potrebno je poznavati vanjsku brzinsku karakteristiku motora i prijenosne odnose u mjenjau.

Za Renault Clio 1.5 dCi (2006):Stupanj prijenosa, N Prijenosni omjer, iN 1 3.73 2 2.05 3 1.32 4 0.97 5 0.76 Red. 3.44

Auto Motor und Sport (22 / 2005)

48

Katedra za motore i vozila

A.2.2 VUNA SILAVuna sila ovisi posredno o brzini vrtnje motora (preko momenta motora):

( FV )Nstupanj mjenjaa:

Mm iN i0 (t )N = rd

Gubici u prijenosu snage (transmisiji) od motora do kotaa, za svaki pojedini

(t )N

1 nm , max = 1 2 1 + 2 1 + 4 i i N 0 100 1000 1 0.83 2 0.87 3 0.89 4 0.90 5 0.92

Stupanj prijenosa, N Iskoristivost transmisije, (t )N

nm, max ... Najvea brzina vrtnje motora u pojedinom stupnju prijenosa [1/min] iN ... Prijenosni odnos u mjenjau za pojedini stupanj prijenosa i0 ... (t )N ... Prijenosni odnos u osovinskom reduktoru Iskoristivost transmisije u pojedinom stupnju prijenosa 49

Katedra za motore i vozila

A.2.2 NAJVEI OKRETNI MOMENT MOTORA

nm [1/min] Mm [Nm]

1000 125

1500 175

2000 200

2500 200

3000 185

3500 165

3750 150

4000 14050

Katedra za motore i vozila

A.2.2 VUNA SILA U POJEDINIM STUPNJEVIMA PRIJENOSA

51

Katedra za motore i vozila

A.2.2 BRZINA VONJEBrzina kretanja vozila kao funkcija broja okretaja motora:

v = opseg kotaa [m] x broj okr. kotaa [1/s] v = 2 rd nk / 60 = 2 rd nm / ( 60 iN i0 )Brzina vozila u pojedinim stupnjevima prijenosa snage (Renault Clio 1.5 dCi):vN = 2 rd nm / ( 60 iN i0 ) = 2 0.29 nm / ( 60 iN 3.44 ) = 0.00885 nm / iNn_m v1 v2 v3 v4 v5 ------------------------------------------------------------[1/min] [m/s] [m/s] [m/s] [m/s] [m/s] ------------------------------------------------------------1000.0 2.36679 4.30640 6.68797 9.10115 11.61595 1500.0 3.55018 6.45960 10.03195 13.65173 17.42392 2000.0 4.73358 8.61280 13.37594 18.20231 23.23189 2500.0 5.91697 10.76600 16.71992 22.75288 29.03986 3000.0 7.10036 12.91920 20.06391 27.30346 34.84784 3500.0 8.28376 15.07240 23.40789 31.85404 40.65581 3750.0 8.87545 16.14900 25.07988 34.12933 43.55980 4000.0 9.46715 17.22560 26.75188 36.40461 46.46378

iN ... i0 ...

Prijenosni odnos u mjenjau Prijenosni odnos u os. reduktoru

nm ... Brzina vrtnje motora [1/min]

52

Katedra za motore i vozila

A.2.2 BRZINA VONJE U POJEDINIM STUPNJEVIMA PRIJENOSA

53

Katedra za motore i vozila

A.2.2 IDEALNA VUNA SILAIdealna vuna sila, tj. vuna karakteristika za sluaj konstantne maksimalne snage:

FV, id = Pe, max / vmax--------------------n Fv,id [1/min] [N] --------------------1000.0 5423.57706 1500.0 3615.71908 2000.0 2711.78970 2500.0 2169.43195 3000.0 1807.85954 3500.0 1549.59402 3750.0 1446.28763 4000.0 1355.89485

Fv, id ... vmax ...

Idealna vuna sila pri zadanom broju okretaja

Pe, max ... Maksimalna efektivna snaga motora Pe, max = 63 kW Maksimalna brzina vozila pri zadanom broju okretaja

Idealna vuna sila prikazana u vunom dijagramu zove se hiperbola vue.

54

Katedra za motore i vozila

A.2.2 VUNI DIJAGRAM

Vune sile u pojedinom stupnju prijenosa moraju tangirati vunu hiperbolu. Vuna hiperbola je idealna vuna karakteristika, tj. krivulja konstantne snage u F,v - dijagramu.55

Katedra za motore i vozila

A.2.2 VIAK VUNE SILEU sluaju vonje brzinom manjom od vmax Razlika raspoloive vune sile,

FV , tj. viak vune sile koji moe posluiti za ubrzanje vozila. Povecanjem brzine v, ta se razlika (mogunost ubrzanja) smanjuje!FV RFV = f (v)

FV

100% opt. Djelom. opt.

vM max

vmax

v

Vuni dijagrama omoguava analizu vunih karakteristika vozila (sposobnost ubrzanja, sposobnost savladavanja uspona i drugih vanjskih otpora). Osnovu za analizu ini viak vune sile, FV .56

Katedra za motore i vozila

A.2.2 DINAMIKI FAKTORIznos FV ovisi o raznim utjecajima, meu ostalima i o Rk . Poto i Rk ovisi o mnogim faktorima (korisno optereenje, kvaliteta podloge) Na osnovu iznosa FV nije mogue direktno zakljuivati o dinamikim sposobnostima vozila. Prikladno je vuno-dinamike karakteristike analizirati pomou izvedenih veliina, koje ne ovise o teini vozila Specifina vuna sila svedena na jedinicu teine vozila ili dinamiki faktor:

D=

FV R z G

Odnos razlike vune sile i otpora zraka prema ukupnoj teini vozila.

57

Katedra za motore i vozila

A.2.2 DINAMIKI FAKTORM m i N i0 (t )N Rz rd F Rz D = V = G GU izrazu za dinamiki faktor prisutne su karakteristike vozila okretni moment motora (Mm ), iskoristivost transmisije (t ), dinamiki radijus kotaa (rd ), itd.

FV = Rk + Rz + Rp + Ru

FV Rz = G fk cos G sin mV

dv dt

D = fk cos sin

dvg dt

=

dvg dtfk ... Koeficijent otpora kotrljanja

U izrazu za dinamiki faktor prisutne su takoer veliine vane za dinamika svojstva vozila brzina i ubrzanje ( dv/dt ), otpor kotrljanja ( fk ), otpor penjanja ( sin ), itd.

... Kut uspon puta [] ... Koeficijent uea rotacijskih masa

... Ukupni koeficijent otpora puta58

Katedra za motore i vozila

A.2.2 DINAMIKE KARAKTERISTIKEZa potpunu analizu vuno-dinamikih karakteristika vozila, potrebno je izraunati vrijednosti D za sve stupnjeve prijenosa i za sve brzine vozila Dinamike karakteristike. U stvarnim uvjetima iznos dinamikog faktora ogranien je najveom ostvarivom vunom silom:FV , max a GaDmax

Granina vrijednost dinamikog faktora:

Dmax =

FV , max R z G

=

a Ga R z G

Do proklizavanja dolazi pri rel. malim brzinama vonje Rz 0 :

Dmax =

a GaG

VJankovi, et al. (2001)

59

Katedra za motore i vozila

A.2.2 DINAMIKE KARAKTERISTIKERavnomjerno (stacionarno) kretanje vozila ubrzanje dv/dt = 0 :

D =Ukupni otpori puta (kotrljanje + penjanje) mogu se, za razliite uspone, prikazati kao horizontalne linije ( f(v) ) u D,v dijagramu.

3

2 1

Jankovi, et al. (2001)

60

Katedra za motore i vozila

A.2.2 DINAMIKE KARAKTERISTIKE1 Pravac presjeca dinamikukarakteristiku u jednoj toki maksimalna brzina vozila u tom stupnju prijenosa je v1 .3

2 Pravac presjeca dinamikukarakteristiku u dvije toke maksimalna brzina vozila u tom stupnju prijenosa je v3 , a stacionarno kretanje mogue i brzinom v2 .

2 1

3 Pravac iznad dinamikihkarakteristika gibanje vozila konst. brzinom nije mogue! Moe biti samo nestacionarno (a = dv/dt < 0) i vremenski ogranieno.Jankovi, et al. (2001)

61

Katedra za motore i vozila

A.2.2 DINAMIKE KARAKTERISTIKEDinamiki faktor, D , omoguuje usporedbu vuno-dinamikih karakteristika za vozila razliitih kategorija (razliite mase i snage motora).

vmax ...

Najvea brzina vozila [m/s]

Dv max ... Din. faktor pri max. brzini Dmax ... Najvei iznos din. faktora u prvom stupnju prijenosa Dpsp ... Najvei iznos din. faktora u najviem stupnju prijenosa

Jankovi, et al. (2001)

62

Katedra za motore i vozila

A.2 VUNE KARAKTERISTIKEA.2.1 A.2.2 A.2.3 A.2.4 A.2.5 Karakteristike pogonskih strojeva Bilanca otpora vonje i vunih sila Bilanca snage Performanse vozila Utjecaj konstrukcijskih parametara na performanse

63

Katedra za motore i vozila

A.2.3 EFEKTIVNA SNAGA MOTORAFunkcija (Leyderman) za izraun krivulje snage motora Pe na temelju jedne poznate toke (Pe, max ):

Pe = Pe, max ( a + b 2 - 3 )

Pe, max ... Najvea efektivna snaga motora [kW] Pe, max = 63 kW = n / n Pe, max n ... Odabrani broj okretaja motora nPe, max ... Broj okretaja motora kod Pe, max nPe, max = 3750 min-1 a, b ... Koeficijenti (za dizelski motor: a = 0.5, b = 1.5, za benzinski motor: a = 1.0, b = 1.0)

64

Katedra za motore i vozila

A.2.3 EFEKTIVNA SNAGA MOTORAEfektvna snaga na raspolaganju pri odabranom broju okretaja motora:Broj okretaja motora, n [1/min] 500 1000 1500 2000 2500 3000 3500 3750

0.13 0.27 0.40 0.53 0.67 0.80 0.93 1.0

Pe [kW]6.46 15.16 25.20 35.69 45.73 54.43 60.89 63.0

65

Katedra za motore i vozila

A.2.3 RASPOLOIVA SNAGA NA KOTAIMARaspoloiva snaga na kotaima za ukljueni stupanj prijenosa:

PN = (t )N PeGubici u prijenosu snage (transmisiji) od motora do kotaa, za svaki pojedini stupanj mjenjaa:

(t )N

= 1

1 nm , max i i 2 1 + 2 1 + 4 N 0 100 1000 1 0.83 2 0.87 3 0.89 4 0.90 5 0.92

Stupanj prijenosa, N Iskoristivost transmisije, (t )N

nm, max ... Najvea brzina vrtnje motora u pojedinom stupnju prijenosa [1/min] iN ... Prijenosni odnos u mjenjau za pojedini stupanj prijenosa i0 ... Prijenosni odnos u osovinskom reduktoru (t )N ... Iskoristivost transmisije u pojedinom stupnju prijenosa 66

Katedra za motore i vozila

A.2.3 RASPOLOIVA SNAGA NA KOTAIMARaspoloiva snaga na kotaima za ukljueni stupanj prijenosa:

PN = (t )N Pen_m P_1 P_2 P_3 P_4 P_5 P_e -----------------------------------------------------------------------[1/min] [kW] [kW] [kW] [kW] [kW] [kW] -----------------------------------------------------------------------500.0 5.36180 5.62020 5.74940 5.81400 5.94320 6.46000 1000.0 12.58280 13.18920 13.49240 13.64400 13.94720 15.16000 1500.0 20.91600 21.92400 22.42800 22.68000 23.18400 25.20000 2000.0 29.62270 31.05030 31.76410 32.12100 32.83480 35.69000 2500.0 37.95590 39.78510 40.69970 41.15700 42.07160 45.73000 3000.0 45.17690 47.35410 48.44270 48.98700 50.07560 54.43000 3500.0 50.53870 52.97430 54.19210 54.80100 56.01880 60.89000 3750.0 52.29000 54.81000 56.07000 56.70000 57.96000 63.00000

67

Katedra za motore i vozila

A.2.3 RASPOLOIVA SNAGA NA KOTAIMA

68

Katedra za motore i vozila

A.2.3 BRZINA VONJEBrzina kretanja vozila kao funkcija broja okretaja motora:

v = opseg kotaa [m] x broj okr. kotaa [1/s] v = 2 rd nk / 60 = 2 rd nm / ( 60 iN i0 )Brzina vozila u pojedinim stupnjevima prijenosa snage (Renault Clio 1.5 dCi):vN = 2 rd nm / ( 60 iN i0 ) = 2 0.29 nm / ( 60 iN 3.44 ) = 0.00885 nm / iNn_m v1 v2 v3 v4 v5 ------------------------------------------------------------[1/min] [m/s] [m/s] [m/s] [m/s] [m/s] ------------------------------------------------------------500.0 1.18339 2.15320 3.34398 4.55058 5.80797 1000.0 2.36679 4.30640 6.68797 9.10115 11.61595 1500.0 3.55018 6.45960 10.03195 13.65173 17.42392 2000.0 4.73358 8.61280 13.37594 18.20231 23.23189 2500.0 5.91697 10.76600 16.71992 22.75288 29.03986 3000.0 7.10036 12.91920 20.06391 27.30346 34.84784 3500.0 8.28376 15.07240 23.40789 31.85404 40.65581 3750.0 8.87545 16.14900 25.07988 34.12933 43.55980

iN ... Prijenosni odnos u mjenjau i0 ... Prijenosni odnos u os. reduktoru nm ... Brzina vrtnje motora [1/min]

69

Katedra za motore i vozila

A.2.3 DIJAGRAM SNAGE

70

Katedra za motore i vozila

A.2.3 MAKSIMALNE BRZINE VONJE U POJEDINIM STUPNJEVIMA PRIJENOSAPrijenosni odnosi za Renault Clio 1.5 dCi (2006):Stupanj prijenosa 1 2 3 4 5 Red.

Prijenosni 3.73 2.05 1.32 0.97 0.76 3.44 omjer

Najvea brzina vozila u pojedinim stupnjevima:Stupanj prijenosa, N Maksimalni broj okretaja motora [min-1] Maksimalni broj okretaja kotaa [min-1] Maksimalna brzina [m/s] Maksimalna brzina [km/h] 1 4450 347 10.5 38 2 4450 631 19.2 69 3 4450 980 29.8 107 4 4450 1334 40.5 146 5 4100 1568 47.6 17271

Katedra za motore i vozila

A.2.3 VUNI DIJAGRAMRealna vuna sila, tj. vuna karakteristika za sluaj realne snage u pojedinim stupnjevima prijenosa, predstavlja omjer snage na kotau i brzine kretanja vozila:

FV (I,II,III,IV,V) = PI,II,III,IV,V / vI,II,III,IV,V

Primjer (za I. brzinu) :----------------------------n_m v_1 Fv_1 [1/min] [m/s] [kN] ----------------------------500.0 1.18339 4.53088 1000.0 2.36679 5.31640 1500.0 3.55018 5.89153 2000.0 4.73358 6.25799 2500.0 5.91697 6.41475 3000.0 7.10036 6.36262 3500.0 8.28376 6.10094 3750.0 8.87545 5.89153

Primjer (za V. brzinu) :----------------------------n_m v_1 Fv_1 [1/min] [m/s] [kN] ----------------------------500.0 5.80797 1.02328 1000.0 11.61595 1.20069 1500.0 17.42392 1.33058 2000.0 23.23189 1.41335 2500.0 29.03986 1.44875 3000.0 34.84784 1.43698 3500.0 40.65581 1.37788 3750.0 43.55980 1.33058

72

Katedra za motore i vozila

A.2.3 VUNI DIJAGRAM

73

Katedra za motore i vozila

A.2 VUNE KARAKTERISTIKEA.2.1 A.2.2 A.2.3 A.2.4 A.2.5 Karakteristike pogonskih strojeva Bilanca otpora vonje i vunih sila Bilanca snage Performanse vozila Utjecaj konstrukcijskih parametara na performanse

74

Katedra za motore i vozila

A.2.4 PERFORMANSE VOZILASkup osobina koje odreuju sposobnost vozila da obavlja pojedine funkcije vua, ubrzanje, savladavanje uspona, itd.

http://www.inforally.sibiul.ro/photo-gallery-5343.html

http://www.draglist.com/artman/publish/daily_pictures/article_001962.shtml

75

Katedra za motore i vozila

A.2.4 SPOSOBNOST REALIZACIJE UBRZANJAv

RSt + RU FV = 0RSt = RK + RZ + RPRSt ... Suma stacionarnih otpora

RSt Gv

T

RU

FV

Ru = m a = m a + m a = RU + RU mv a = ( Gv / g ) am ... Stvarna masa vozila ( m = mv ) [kg] m ... Dodatak masi vozila uslijed rotirajuih dijelova a ... ...

Translatorno ubrzanje vozila (tangencijalno ubrzanje na obodu kotaa) [m/s2] Koeficijent uea rotacijskih masa, vrijednosti za osobne automobile: 1.15 1.18 ... za 1. stupanj prijenosa 1.05 1.06 ... za najvii stupanj prijenosa

76

Katedra za motore i vozila

A.2.4 SPOSOBNOST REALIZACIJE UBRZANJAa = g GV

( FV

R St

)=

g GV

( FV

RK RZ RP

)=

g GV

( D f K cos sin ) G V

D=g

FV R z GV

a=

( D f K cos sin )U sluaju vrlo velike redukcije Velik utjecaj rot. masa Velik 1

FV

a2 3 4 5

1

a2 3 4 5

1

2 3 4 5

v

v

v77

Katedra za motore i vozila

A.2.4 SPOSOBNOST REALIZACIJE UBRZANJAUbrzanje je openito ogranieno adhezivnom sposobnou pogonskih / vunih kotaa:

( FV )max = a Gaamax = g (a Ga RSt ) Gv

(FV )max ... Najvea ostvariva vuna sila [N]

a ...

Adhezivni koeficijent trenja [-] Optereenje kotaa na pog. osovini, tj. adhezivno optereenje [N] Teina vozila [N]

a) Poetak kretanja (start): RSt = 0, 1

Ga ... Gv ...

amax = g

Ga G a 10 a a Gv Gv

b) Poetak kretanja (start) za vozilo 4x4: Ga = Gv

amax = g a 10 a78

Katedra za motore i vozila

A.2.4 VRIJEME POTREBNO ZA UBRZANJEVrijeme potrebno da se postigne odreena brzina za sluaj kretanja s mjesta (v1 = 0), konstantnim ubrzanjem (a = const.):a= dv dt dt = dv at2 v2

t1

dt =

v1

a dvVrijeme potrebno za promjenu stupnja prijenosa

1

Priblian proraun:n 1 t = v t = t i a i =1

a

1

1/a5 2 3 4 2 5 1 3 4

tt 2 1 3

t

1/a

v

v

v

100

v79

Katedra za motore i vozila

A.2.4 PUT POTREBAN ZA UBRZANJEPrijeeni put potreban da se postigne odreena brzina za sluaj kretanja s mjesta i s konstantnim ubrzanjem (a = const.):v= ds dts2 t2

ds = v dt

s1

ds = v dtt1n

Priblian proraun:s = v t s = s ii =1

t3

s v

s

t

s1

2

v

t

v80

Katedra za motore i vozila

A.2.4 SAVLADAVANJE USPONAZa projektiranje motornih vozila uspon u postocima [s %]:

tan = s / 100g

s [%]a g

1 2 3 4 5

a=

( D f K cos sin )

sin = D f K cos

Za male uspone: 0 cos 1 tan sin s 100 D fK a g Za vee uspone (a 0): a s = 100 tan arc sin D fK cos g 100 tan (arc sin (D fK cos ))

v

81

Katedra za motore i vozila

A.2 VUNE KARAKTERISTIKEA.2.1 A.2.2 A.2.3 A.2.4 A.2.5 Karakteristike pogonskih strojeva Bilanca otpora vonje i vunih sila Bilanca snage Performanse vozila Utjecaj konstrukcijskih parametara na performanse

82

Katedra za motore i vozila

A.2.5 ...UTJECAJ MASE (OPTEREENJA)...

83