Search

Posljednjih godina, osim laboratorijskih ispitivanja, za određivanje emisija iz cestovnih motornih vozila provode se i ispitivanja u stvarnim uvjetima vožnje RDE (engl. Real Driving Emissions - RDE) uz upotrebu prijenosne mjerne opreme PEMS (engl. Portable Emissions Measurement System - PEMS). U radu su prikazani rezultati mjerenja emisija provedenih na vozilu VW Caddy 1.4 TGI opremljenim za pogon motornim benzinom Eurosuper 95 i stlačenim prirodnim plinom SPP-om (engl. Compressed Natural Gas - CNG). Cilj istraživanja bio je utvrđivanje emisija štetnih tvari i ugljikova dioksida, odnosno potrošnje goriva, u skladu s propisanom RDE procedurom te usporedba rezultata za dvije navedene vrste pogonskog goriva.

Public transportation and the transportation of goods in urban areas is becoming more and more complex task, especially due to increased awareness of its impact on the environment. One of the solutions could be a flexible transport system which could be fitted with different powertrain solutions, according to the region of its deployment. Croatia is a Mediterranean country and is in a need for such a solution. Its coastal cities are characterized by narrow streets which pose a problem for conventional city busses and delivery trucks. The objective of the project described in this paper was the development of a modular vehicle which could be used as a low floor minibus or as a commercial delivery vehicle fitted with an electric, hybrid or conventional powertrain and which could provide a suitable transportation solution for Croatia’s coastal cities and similar European cities. The project started in 2007 when the Chair of IC Engines and Motor Vehicles of the Faculty of Mechanical Engineering and Naval Architecture on the University of Zagreb joined forces with the newly formed company called AZ Crobus. AZ Crobus had an ambition to restart the bus production in Croatia and the idea was to offer a unique niche product along with a standard intercity bus. The development task was to develop a vehicle with a gross weight up to 6, 000 kg and a high percentage of low floor area which could carry up to 35 passengers. During the development process two vehicle concepts were developed and evaluated. The better rated vehicle concept was further developed and design solutions for some critical components (axles and steering system) were developed. The cooperation between the Chair of IC Engines and Motor Vehicles and AZ Crobus ended by the end of 2008 due to financial reasons but the project was further developed on the Chair of IC Engines and Motor Vehicles. The design process was greatly supported with modern CAD tool, FEM (finite elements method) and MBD (multibody dynamics) simulation and optimization tools. The paper offers a review of the development of an innovative vehicle concept carried out in Croatia.

Climate changes, continuous increase of energy consumption in transport and requirements for reducing dependency on oil import, promote the use of alternative fuels in motor vehicles. The most used alternative fuel in Europe is liquefied petroleum gas (LPG), which currently propels around 3% of passenger cars in Europe. Since the LPG is produced by refining the crude oil or by separation from natural gas, in the paper comparison of LPG with gasoline and gaseous fuels of fossil origin (compressed natural gas (CNG), liquefied natural gas (LNG)) and gaseous fuels of organic origin (biogas) has been made. Except the fuel composition, technical level or generation of LPG system installed in the vehicle impacts the emissions, so an overview of existing systems and their major components is given. By analysing the data of registered motor vehicles of category M1 (passenger cars) in the Republic of Croatia for vehicles powered by LPG categorization of vehicle age, mileage, emission standard and generation LPG system installed in the vehicle is made. This categorization enables estimation of emissions from LPG powered motor vehicles.

In order to meet the required performance (power and torque), and to simultaneously reduce the fuel consumption and exhaust gas emissions, modern spark-ignition (SI) engines are usually turbocharged and "downsized". High intake pressure at the cylinder inlet increases the tendency of knocking combustion. The presence of knock reduces the overall engine efficiency, combustion stability and structural durability. The applications of different fuels and their blends, different combustion chamber designs, lean stratified mixtures, different levels of exhaust gas recirculation (EGR), together with the spark-timing settings enables the reduction of knock occurrence. On the other hand, high EGR ratios increase the cyclic variability in combustion which leads to unstable engine operation. In order to minimize cyclic variability and knock occurrence it is necessary to find the compromise between the engine operating parameters. In this paper the numerical analysis of a four cylinder SI engine performance is made, with the emphasis on the knock occurrence and the cyclic variability. For the validation of ignition, turbulence and combustion sub-model constants, the experimental results of multi cylinder SI engine were used as the averaged results over four engine cylinders. The ignition, turbulence and combustion sub-model constants were optimized at the different operating conditions with a single cylinder (reduced) engine model. After validation of the simulation model constants on the reduced single cylinder model, the full engine cycle-simulation model is made representing the modern multi cylinder SI engine. The applied cycle-simulation model includes modelling of the early flame kernel growth, mixture stratification, turbulent combustion, in-cylinder turbulence, knock and cyclic variability over 300 cycles. For several operating points of the four cylinder SI engine, the optimum operating parameters (such as spark advance, EGR ratio, intake pressure) were found to meet the imposed requirements in terms of fuel consumption, percentage of knocking cycles and variation of indicated mean effective pressure (IMEP). The presented methodology represents the fast and well promising tool for a definition of engine operating conditions and performance even in the conceptual development phase.

One of the measures for increasing the thermal efficiency and reducing the fuel consumption of spark-ignition engines is the increase of compression ratio of the engine. Due to the nature of combustion process in a spark-ignition engine, the occurrence of knock presents one of the biggest obstacles in increase of compression ratio. Modern SI engines apply high levels of boost in order to reduce the overall losses. To avoid knock in these conditions the engine manufacturers often have to reduce the compression ratio. Engine knock occurs after the start of main combustion do to auto ignition of hot-spots in the end gas. The main parameters which influence the onset of auto ignition (knock) are the in-cylinder pressure, end gas temperature, end gas composition and the chemical reactivity of the fuel. The tendency of a specific fuel to knock in a fuel-air mixture is expressed with the octane number of the fuel which is determined by a standard procedure in an experimental CFR (Cooperative Fuels Research) engine. Larger octane number of the fuel means that this fuel is less prone to knock. In this paper a potential for change in fuel consumption and thermal efficiency of an engine running with fuels that have different octane ratings is analyzed. The change of thermal efficiency comes from the possibility to run the engine with higher compression ratio when higher octane rating fuel is applied. In this work the following fuels are analyzed: methane, n-heptane and gasoline. For the analysis a 1-D/0-D model of the engine was made in the AVL Boost software package. In the calculations a newly developed multi-zone knock model and a physical combustion model which is able to simulate the cycle-to-cycle variations of combustion was used. The combustion model and the knock model were calibrated with the data from the experimental measurements on the engine.

As a result of the latest trends in the automotive industry that have put stringent requirements on the fuel consumption and exhaust gas emission, the engine research has been directed towards optimization of the combustion process and application of the variety of cleaner fuels. In that context the use of natural gas as a partial supplement for the liquid Diesel fuel has attracted a lot of attention. This paper presents the literature review of recent research on dual fuel Diesel-natural gas operation. It presents the benefits and drawbacks of dual fuel Diesel-natural gas operation as well as the means and methods to circumvent these drawbacks. The use of natural gas as a partial supplement for Diesel liquid fuel has been suggested due to its cleaner nature of combustion, its worldwide availability and its potential to reduce both global (CO2) and local (NOx, soot) exhaust gas emissions from conventional Diesel engines. As natural gas is consisted primarily of methane (CH4), it has high H/C ratio thus having the theoretical potential to reduce the CO2 emission by nearly 25% compared to conventional Diesel fuel. What makes dual fuel operation possible is the flammability limit between the two fuels and it exploits the advantages of each one. Diesel fuel pilot is used as a high energy ignition device (Diesel fuel pilot releases 10000 times more energy compared to the energy delivered by spark the in spark-ignition engine) while natural gas is used as a primary fuel in the operation. Several dual fuel combustion strategies have been proposed ; (a) conventional dual fuel combustion that operates with premixed natural gas which is ignited by the Diesel fuel pilot ; (b) direct injected dual fuel combustion, where both natural gas and Diesel pilot fuel are directly injected into the cylinder at the end of the compression stroke ; (c) HCCI like combustion (PCCI, RCCI) where combustion is primarily controlled by the natural gas/Diesel fuel ratio. Although dual fuel combustion has shown significant potential it still faces some challenges, among which HC and CO emission at low load and preignition and knock at high load are the major ones.

The paper presents influence of the crankshaft offset of spark ignition engine regarding the engine friction, torque and power. It is known from the literature that crankshaft offset has a potential to reduce normal piston force during the expansion stroke at lower engine speeds. The results of lower normal force are reduced mechanical losses due to friction between the piston and liner of the cylinder. The crankshaft offset can significantly change the piston kinematics because the piston moves slower around TDC and BDC. If spark timing is referenced to the piston position from the TDC, the crankshaft offset increase in-cylinder pressure during the combustion as a result of lower change of the cylinder volume close to the TDC and engine performances can be improved. Two operating points of spark ignition engine were analyzed and optimization of crankshaft offset was performed by the NSGA-II genetic algorithm. In order to calculate the active piston force during the combustion process Vibe function were applied. The minimization of friction losses that occur between piston and cylinder liner as well as minimization of difference between peak values of resultant force of the piston in the normal direction were the main objectives of the optimization. The optimization results show that crankshaft offset has potential to improve engine performances at lower engine speeds.

Homogeneous charge compression ignition [1, 2] is a relatively new type of combustion which offers a possibility to combine the benefits of Diesel and Gasoline engines. It has a potential to achieve very high efficiencies with low NOx and particulate emissions [3]. Main current limitations that prevent the commercial application of HCCI combustion are low power density and control of combustion timing. One of the recent trends for achieving high power densities is high boosting levels of these engines [4]. Nevertheless, control of combustion timing still remains an issue. For the control of combustion timing there are several proposed strategies that can be used: fast thermal management, recirculation of exhaust gases, exhaust gases re-breathing, residual gas trapping, variable compression ratio, variation of fuel blend, etc. In order to be able to asses the potentials of these strategies and to be able to develop control algorithms for these strategies, fast simulation models of HCCI engines are required. In recent years several control oriented models have been developed [5-14]. Some of them are mean value models and some of them are crank angle resolved models. In most of the models the well known integral functions (Arrhenius rate, knock integral, etc.) are used for a definition of start of combustion, and combustion progress is modeled by Vibe functions with mostly constant parameters. The use of integral functions means that for each fuel a specific function has to be defined, or there is a need for ignition delay data over the large possible operating conditions. Also, these models are individually developed and are not available to wide combustion research community. The work presented here is a part of the wider research work whose aim is to define steps necessary to build a fast HCCI engine model by using available commercial software. The idea is that a model could use Vibe combustion, which is fast enough, whose parameters are functions of operating conditions. In the first part of this work the analysis of state factors which are influencing the Vibe combustion parameters is made, and the regression functions which calculate combustion parameters on the basis of defined state factors are derived. By using these functions one can calculate Vibe parameters on the basis of state in the cylinder at a certain moment and use them during combustion event. These functions are shown to be valid in a stable HCCI operating region. In order to have a fully flexible model a definition of boundaries of the HCCI operating region has to be defined which is a second part of the overall work, and is not presented here. All the data that are used in the analysis and in calculations of the regression functions are obtained by a calculation with six-zone HCCI combustion model which uses detailed chemical kinetics and is implemented into the AVL Boost. Ethanol is used as a fuel, i.e. the reaction mechanism of ethanol with 58 species and 310 reactions. Parameters of double Vibe combustion are analyzed instead of standard Vibe, but the procedure could be applied for a single Vibe also. Final results show that by using double Vibe parameters calculated by regression functions it is possible to simulate pressure trace reasonably well. Since this simulation is several hundreds of times faster than the detail kinetics one the use in calculation of transients is enabled. Also since double Vibe combustion model is available in commercial cycle simulation software, like AVL Boost, this approach is available to wide combustion research community.

The paper describes the measurement and generation of 3D models of various vehicles on whom significant design changes had to be made. In order to make the required design changes on the original vehicle, a 3D model of the vehicle had to be created. These modification and adaptation tasks had to be done without any technical drawings of the original vehicle. Therefore, the original vehicle had to be measured in order to create the CAD model of the vehicle. A vehicle is a complex shaped object and it is not always practical or possible to measure it using conventional measuring methods. The surface of such objects and specific points on the object can be digitized with various (optical) measuring systems. Based on gathered digital measuring data and via specialized software packages, 3D CAD models can be easily created. The obtained models represent a good basis for adaptation design interventions and various analysis and simulation tasks required for making good decisions regarding the design changes. For such purposes, two measuring systems were used: TRITOP and ATOS. TRITOP is a high precision measuring system which determines the 3D coordinates of markers and other visible elements on the surface of the measured object and ATOS is a digitizing system that enables a quick measurement of the surface of the measured object with high local resolution. TRITOP was used for the measurement of the city bus that had to be converted into a panoramic bus for city sightseeing and ATOS was used to digitize the driver’s door and the door frame of a production car in order to model the body of a Dakar rally vehicle and to digitize the rear door and the rear door frame of the vehicle for whom a new mechanism for rear door opening had to be developed.

Korištenje optičkih mjernih sustava u reverzibilnom inženjerstvu.

The paper describes the use of optical measurement systems in reverse engineering processes that ware performed on various vehicles Here the use of two systems will be shown, TRITOP and ATOS. The TRITOP system was used in the process of digitalization of the body structure of an old city bus. T he body structure is obtained by determination of the 3D coordinates of markers and other visible elements placed on the bus body structure. The ATOS system was used for the scanning of the surface of the drivers door and the door frame of an Opel Antara which was the basis for the body of the Dakar rally vehicle.

The paper describes the development of multifunctional low floor vehicle (GVW 6000 kg) steering system, for the front steering axel with an independent suspension with a McPherson strut and a bottom transverse link. The axel capacity is 3600 kg. During development the priority was to fit the steering system in the available space, while achieving better ground clearance at the same time. Furthermore, in order for the vehicle to have better manoeuvring ability in narrow streets, it was the maximal steer angle of the inner wheel had to reach 50°. From the aspect of production efficiency, already manufactured components available on the market were to be used as much as possible. In those conditions the aim was to develop a steering system with rotating levers and if possible totally straight rods, driven by a standard hydraulic steering gear. For these demands possible steering system configurations were selected and analyzed, and the most suitable one was chosen. Further development of the chosen steering system includes the elaboration of its kinematics. In case of the steering system combined with the independent suspension, vertical motion of the wheel affects the position of the steering system rods. It is important that the steering rods follow steer angle, in order to avoid possible unwanted steer angle changes due to the upward and downward deflections of the wheel. The positions of vehicle suspension joints on the transverse vertical plain through the front axel defines the positions of steering system joints on the same plain. The positions of steering system joints on the transverse vertical plain of the front axel were determined by implementing the virtual centres procedure. Although the position of the joints on the horizontal plain is generally defined by the design of the vehicle's front axel and the steering system itself, their optimal positions are determined by implementing the flexible polyhedron method. Optimization is carried out using the criteria of minimal differences between the actual steer angle curve and the Ackermann's curve. That determines the positions of joints of the steering system, in accordance with the given geometrical limits. Diagrams are used to show differences between the actual steer angle curve and the Ackermann's curve, before and after the optimization process.

U radu je opisan razvoj propisa o dozvoljenim emisijama štetnih tvari iz Dieselovih motora teretnih vozila i autobusa u Europi u razdoblju od 1990. godine do danas, s osvrtom na njihov razvoj u budućnosti. Dane su vrijednosti dozvoljenih graničnih vrijednosti emisija štetnih tvari za pojedini stupanj strogoće propisa i prikazani ispitni ciklusi prema kojima se ta emisija ispituje. Kratko su opisani sustavi EGR za povrat ispušnih plinova i SCR za selektivnu katalitičku redukciju pomoću kojih je moguće ispuniti zahtjeve trenutno važećih propisa te je prikazana moguća konfiguracija sustava za naknadnu obradu ispušnih plinova koji bi Dieselovom motoru trebao osigurati budućnost u svjetlu sve strožih emisijskih zahtjeva.

U radu je opisan razvoj propisa o dozvoljenim emisijama štetnih tvari iz motora s unutarnjim izgaranjem u Europi u razdoblju od 1970. godine do danas, s osvrtom na njihov razvoj u budućnosti. Osim na zakonski ograničene emisije štetnih tvari, dan je osvrt i na zahtjeve na gorivo potrebno za ispunjavanje propisa Euro 5 i 6 kao i na emisiju CO2, plina koji nije zakonski ograničen, ali je staklenički plin na kojeg se odnosi sporazum iz Kyota. Znatan napredak u smanjenju emisija štetnih tvari postignut je kontinuiranim poboljšavanjem tehnika pročišćavanja ispušnih plinova i upotrebom sve kvalitetnijih goriva. Pritom treba naglasiti da se kvalitete goriva koje zahtijeva Svjetska povelja o gorivu Worldwide Fuel Charter - WWFC, koja predstavlja želje proizvođača motora, razlikuju od kvalitete goriva koju zahtijevaju propisi EU. Razvoj budućih propisa o emisiji i zahtjeva za kvalitetom goriva predstavlja isprepletene želje i mogućnosti proizvođača motora i vozila, proizvođača goriva, politike i zakonodavstva te pritiska „ zelenih“ . Posebnu težinu za donositelje zakonskih propisa u EU ima činjenica da je EU ovisna o uvozu goriva i svojevrsni je lider na području primjene alternativnih goriva i donošenja novih strožih propisa vezanih za emisije štetnih tvari.

The paper shows usage of modern systems for optical measuring in reverse engineering methods. When due to large dimensions of the measuring object and its complexity it is not practical or possible to use conventional measuring methods, the surface of these objects or points on them can be digitized, and based on that, 3D CAD models can be created. The obtained models represent a good basis for further construction development, analysis and simulation. For this purpose two measuring systems are used: TRITOP and ATOS. High precision measuring system TRITOP determines the 3D coordinates of markers and other visible elements on the surface of the measured object, what allows quick and efficient on site measurement. This system was used in the first example for determining the position of the centerline end-points at the body structure of a city bus. Obtained computer wireframe model was the basis for creation of 3D CAD and FEM models. The second system, ATOS, determines the three-dimensional coordinates of points with two digital cameras which record the object’s surface, based on the principle of triangulation, thus generating a polygon mesh which describes the form of the digitized object. In the second example this system was used to digitize door frame and door. The obtained 3D CAD models were the basis for synthesis and analysis of a new mechanism of side door opening of a personal vehicle adapted for a disabled person.

The paper shows a modification procedure of a city bus into a touristic panoramic bus. The goal of this modification is to enable easier tourists sight-seeing while driving on the bus. This intervention requires significant modifications on the vehicle’s body structure, removing solid roof and its carrier, and making two security frames (rollbars) with the aim of protecting passengers in the event of bus rollover. Requirement for placing the modificated bus in the public transport and at the same time the project request, is that the security frames (rollbars) and modified body structure must be strong enough so that in case of rollover bus is leaned over security frames. These frames and the modified body structure must be able to endure the static load, which corresponds to the maximum technical permissible mass of the vehicle. By using the method of finite elements a strength analysis (calculation) was made for the requested load case applied to the proposed construction solution of security frames (rollbars) and modified body structure. This analysis showed that the stresses in such construction would not exceed the Yield strength of materials and that the security frames or body structure will not fracture. By checking the stability (buckling load) of security frame, it was established that there would be no loss of structure stability.

Greenhouse gas (GHG) emissions of road transport amount to less than 0.3 % of global emissions. Therefore, it would be more efficient to reduce them in other fields, e.g.in the building industry. In spite of that, road transport is pointed out, even in the Kyoto Protocol, as one of the most important targets when the reduction of the global GHG emissions is concerned. However, Germany is the only country among all European countries which has reached the planned decrease in GHG emissions, which means that there are considerable difficulties in achieving the promoted goals. Looking to the future, demands like improved engines and fuels have more chances to sustain the mobility than new power train systems based on expensive, disputable hydrogen technology. Bearing all this in mind, there is room for doubt whether GHG emissions from road transport should be so severely restricted.

U radu su prikazani podaci o emisijama stakleničkih plinova, te su iskazane rezerve prema obvezama sporazuma iz Kyotoa. Udio cestovnog prometa u ukupnim emisijama CO2 na Zemlji iznosi samo 0, 3 %. Proklamirane ciljeve u smanjivanju CO2 od cestovnog prometa ispunila je samo Njemačka. Ona prednjači i u smanjivanju potrošnje goriva vozila. Navedene su mogućnosti smanjenja emisija CO2 poboljšanjima motora i vozila te primjenom alternativnih goriva. Ukazano je na činjenicu da bi se emisije CO2 mogle znatno jeftinije i učinkovitije smanjiti u drugim sektorima gospodarstva nego boljim vozilima. Izgledi vodika kao rješenja za buduću održivu mobilnost nisu obećavajući. Utjecaj cestovnog prometa na povećanje koncentracije stakleničkih plinova u atmosferi je beznačajan.

U radu su prikazane promjene dozvoljenih granica emisija štetnih tvari iz motora s unutarnjim izgaranjem u Europi u razdoblju od 1970. godine do danas, s pogledom na budućnost. Tako su npr. od 1990. godine tijekom samo 15 godina granice smanjene i za više od 85 %. Osim smanjivanjem sirovih emisija motora, ovakav je napredak postignut istovremenom primjenom poboljšanih tehnika pročišćavanja ispušnih plinova i kvalitetnijih goriva. Pritom se kriteriji Svjetske povelje o gorivu WWFC, koja predstavlja želje proizvođača motora, razlikuju od granica usvojenih homologacijskim propisima, a atribut „ euro“ u nazivu goriva ne označava posvuda u Europi uvijek istu kvalitetu. Ottovi motori koji rade sa siromašnom smjesom zahtijevaju drugačije katalitičke konvertore. Kod Dieselovih motora prema sadašnjem stanju tehnike izgleda da su common-rail i sustav selektivne kataličke redukcije rješenja za budućnost.

Transport seže daleko u povijest no u današnjem društvu i trgovini sve je veća potreba za brzim i učinkovitim prijevozom tereta i robe, što je dovelo do sve većeg razvoja teretnih vozila i nadogradnji specifične namjene. Ovaj rad se fokusira na razvoj nadogradnje za prijevoz rasutih terete odnosno kiper vozilo N1 kategorije. Prvo se razmatraju kategorije vozila za prijevoz tereta i propisi vezani uz dimenzije, masu i osovinska opterećenja. Na temelju zahtjeva proizvođača izrađuje se lista kriterija koje nadogradnja treba ispuniti, a potom vodeći se po tim kriterijima odabirana su adekvatna konstrukcijska rješenja. Nakon odabira koncepta, započinje se s razradbom faze koja uključuje odabir vozila i šasije te oblikovanje podkonstrukcije i sanduka, uz proračune čvrstoće podkonstrukcije, osovinskog opterećenja i opterećenja hidrauličkog cilindra. Nakon toga se odabire hidraulički cilindar za podizanje sanduka te se izračunava konačna nosivost. Na kraju se izrađuje 3D model nadogradnje za rasute terete i pripadajuća dokumentacija. Transport dates back far in history, but in today's society and trade, there is an increasing need for fast and efficient transport of goods and cargo, which has led to a growing development of specialized cargo vehicles and upgrades. This paper focuses on the development of a truck superstructure for the transport of bulk cargo, specifically a category N1 tipper truck. It begins by examining the categories of cargo vehicles and the regulations that govern their dimensions, weight, and axle loads. A set of criteria that the superstructure must fulfill is then established based on the manufacturer's requirements. Following the selection of an appropriate concept, the development phase begins, which includes selecting vehicle and chassis, designing the substructure and cargo box, calculating the substructure's strength, axle load, and hydraulic cylinder load. Next, a hydraulic cylinder is selected for lifting the cargo box, and the final carrying capacity is calculated. Finally, a 3D model of the bulk cargo upgrade and accompanying documentation is created.

U ovom radu prikazan je borbeni robot „Kremenko“ koji je sudjelovao u prvim studentskim borbama robota u Fightbotics organizaciji. Koncept takvog borbenog robota, jedini svoje vrste koji se pojavio među natjecateljskim izrađenim robotima naziva se „Flamebot“. Ima karakteristično oružje, odnosno mogućnost iskrenja vatre, kojom može zapaliti protivničkog robota. Obrađeni su još karakteristični modeli koji su sudjelovali na natjecanju, te je pružena analiza modela sukladno mehaničkim i dinamičkim svojstvima pojedinog modela. Opisan je i Pravilnik natjecanja u kojem se nalaze pravila za izradu, ali i sudjelovanje u natjecanju. Uz rad je priložena tehnička dokumentacija razrađenog koncepta fighbota „Kremenko“. In this thesis is represented battle bot „Kremenko“, who has participated in the first student battle of robots in the organization of Fightbotics. Concept of such battle bot, the only one of its kind in the competition among other contestants is called “Flamebot”. It has a characteristic weapon, and that is ability for sparking fire, which can be used to set opponents battle bot on fire. Other standard models that participated in the competition are also described, and they are given model analysis according the mechanical and dynamical properties. Document “Pravilnik”, that represents rules of the competitions, is also described, which besides the rules for contestants, contains rules for building and modeling battle bot. The thesis is accompanied by technical documentation of the battle bot “Kremenko”

Zbog potrebe povećanja sigurnosti u poljoprivrednim poslovima na snazi je zakon koji nalaže da svi traktori proizvedeni nakon 1983. godine moraju imati ugrađenu neku vrstu zaštitne konstrukcije. U sklopu ovoga rada prikazana je kategorizacija zaštitnih konstrukcija namijenjena za traktore od 1.5 do 4 tone. Nadalje, detaljno je proučen pravilnik TPV 310, kojim se definira način opterećivanja zaštitne konstrukcije. Od tri predstavljena koncepta okvira, odabire se najpogodniji prema listi zahtjeva. Donesen je zaključak da će se konstruirati dvije zaštitne konstrukcije: prva za manje traktore do 2t i druga za traktore od 2 do 4 t. Nakon konstruiranja, provjeravani su pomaci zaštitne konstrukcije te dali dolazi do narušavanja vozačevog prostora, određenim pravilnikom TPV 310. Nakon toga, na obje konstrukcije provjerila su se kritična mjesta na konstrukciji, zavari i vijci. Na kraju je izrađen 3D model za obje zaštitne konstrukcije, kao i pripadajuća dokumentacija. Due to the need to increase safety in agricultural operations, there is a law in force that mandates that all tractors manufactured after 1983 must have some type of protective structure installed. As part of this paper, the categorization of protective structures intended for tractors from 1.5 to 4 tons is presented. Furthermore, the rulebook TPV 310, which defines the method of loading the protective structure, was studied in detail. From the three presented frame concepts, the most suitable one is selected according to the list of requirements. It was concluded that two protective structures will be constructed: the first for smaller tractors up to 2t and the second for tractors from 2 to 4t. After construction, the movements of the protective structure were checked to see if there was a violation of the driver's space, specified by the TPV 310 regulation. After that, critical places on the structure, welds and bolts were checked on both structures. At the end, a 3D model was created for both protective structures, as well as the associated documentation.

U ovom radu prikazan je razvoj cilindarskog bloka hlađenog rashladnom tekućinom za eksperimentalni motor za istraživanje naprednih procesa izgaranja. Motor je značajno prerađeni jednocilindarski Hatz 1D81 koji se nalazi u Laboratoriju za motore i vozila na Fakultetu strojarstva i brodogradnje u Zagrebu. Cilindarski blok izveden je tako da su se postojeće komponente na motoru preradili ili nanovo izradile kako bi se integrirale u postojeću konstrukciju motora. Prije početka razvoja utvrđeni su zahtjevi koje je potrebno ispuniti, mjerenjem je određen dostupan prostor za nadogradnju i izračunat je potreban protok rashladne tekućine. Nakon toga je provedena funkcijska dekompozicija sustava. Svi podaci koji su korišteni za određivanje konstrukcijskih zahtjeva i za provedbu proračuna dani su od strane fakulteta ili su preuzeti iz navedene literature. S obzirom na funkcijsku strukturu sustava napravljeni su koncepti za izvedbu hlađenja cilindra motora, koji je samo dio spomenutog sustava. Ostale komponente sustava nisu detaljnije obrađene jer nisu tema ovog rada, nego su samo utvrđeni parametri koju su potrebni za izvedbu sustava. Za odabrani koncept je napravljena detaljnija konstrukcijska razrada i provedeni su analitički proračuni za bitnije dijelove konstrukcije. Nakon toga su napravljeni 3D modeli i tehnička dokumentacija. This paper presents the development of a coolant-cooled cylinder block for an experimental engine for research into advanced combustion processes. The engine is a significantly modified single-cylinder Hatz 1D81 which is located in the Laboratory for Engines and Vehicles at the Faculty of Mechanical Engineering and Naval Architecture in Zagreb. The cylinder block was designed so that the existing components on the engine were reworked or rebuilt to be integrated into the existing engine construction. Prior to the development start, the requirements that needed to be met were determined, measurements of the available space for upgrade were made and the required coolant flow was calculated. After that, the functional decomposition of the system was carried out. All the data used to determine the design requirements and to carry out the necessary calculations were provided by the faculty or were taken from the cited literature. Following the functional decomposition, concepts for the cylinder cooling design were created, which is only a part of the aforementioned system. Other components of the system are not processed in detail because they are not the subject of this paper, only the necessary parameters required for the performance of the system have been determined. For the chosen concept, further development was made and analytical calculations were carried out for the most important parts of the design. After that, 3D models and technical documentation were created.

U ovom radu je prikazana prerada eksperimentalne glave motora Hatz 1D81 s hlađenja zrakom na hlađenje tekućinom. Eksperimentalni motor se koristi u Laboratoriju za motore i vozila na Fakulteta strojarstva i brodogradnje u Zagrebu. U uvodnom dijelu rada objašnjene su vrste i funkcije glave motora, provedena je analiza prednosti i nedostataka hlađenja zrakom i hlađenja tekućinom, te su se dale osnovne informacije o izvornom i dosad prerađenom motoru Hatz 1D81. Nadalje su objašnjeni zahtjevi koje prerađena glava motora mora zadovoljiti i na temelju toga konstruirana su dva konceptna rješenja prerade glave. Koncepti su uspoređeni prema zadanim kriterijima i odabran je jedan koncept koji je detaljnije razvijen. Odabrani koncept omogućuje rad Ottovog motora s pretkomorom, Ottovog motora s unutarnjom pripremom smjese i Dieselovog motora s direktnim ubrizgavanjem goriva u prostor izgaranja. U drugom dijelu rada objašnjena je konstrukcijska razrada prerade glave koja uključuje strojnu obradu, izračun kritičnih brzina strujanja rashladne tekućine, analitički proračun za dijelove poput vijaka i limova za držače komponenti za pripremu i paljenje smjese. Također proveden je proračun naprezanja glave motora pomoću metode konačnih elemenata u programskom paketu Abaqus. Na kraju je izrađen 3D model prerađene glave motora i pripadajuća dokumentacija u programskom paketu SolidWorks. This thesis presents the conversion of the experimental cylinder head Hatz 1D81 with air cooling to liquid cooling. The experimental engine is located in the Laboratory for engines and vehicles at the Faculty of Mechanical Engineering and Naval Architecture in Zagreb. In the introductory part of the thesis, the types and functions of the cylinder head were explained, the advantages and disadvantages of air cooling and liquid cooling were analyzed, and basic information was given about the original and so far modified Hatz 1D81 engine. Furthermore, the requirements that the modified cylinder head must meet were explained, and two concept solutions of the cylinder head were created based on this. Those concepts are then compared according to the given criteria and one is chosen for further development. In the second part of the work, the structural elaboration of the head processing is explained, which includes machining, calculation of critical coolant flow rates, analytical calculations for parts such as bolts and component holders for preparing and igniting the fuel mixture. The cylinder head stress calculation was also carried out using the finite element method in the software Abaqus. At the end, a 3D model of the modified cylinder head and technical documentation were created in the software SolidWorks.

Zbog sve veće potrebe za razvojem društva i trgovine te povezivanja svijeta sve je veći i brži razvoj teretnih vozila koja osiguravaju prijevoz različitih vrsta dobara. Zbog toga se razvijaju i mnoge vrste nadogradnji za teretna vozila specifična za pojedine grane industrije. U ovom radu prikazan je razvoj nadogradnje za rasute terete. Na početku rada prikazana je kategorizacija vozila za prijevoz tereta te zakonske odredbe i propisi u vezi s dimenzijama i masom vozila te osovinskim opterećenjima. Nadalje su prikazani zahtjevi i upute proizvođača odabranog teretnog vozila na koji se postavlja nadogradnja. Prema tome je izrađena lista kriterija koje nadogradnja treba ispuniti i s time se išlo u konceptualnu fazu gdje su bila predstavljena tri koncepta koja su vrednovana prema odabranim kriterijima. Razradbena faza započela je odabirom vozila i šasijom, a nastavila se oblikovanjem podkonstrukcije i sanduka (okvir i stranice) te veza šasije i podkonstrukcije. Izvršen je proračun čvrstoće podkonstrukcije, osovinskog opterećenja, opterećenja hidrauličkog cilindra u tri kritična slučaja (početak podizanja sanduka, bočno kipanje i stražnje kipanje) te proračun oslonaca sanduka. Nakon toga se odabrao hidraulički cilindar za podizanje sanduka i izvršio izračun konačne nosivosti. Na kraju je izrađen 3D model nadogradnje za rasute terete i pripadajuća dokumentacija. Due to the growing need for the development of society and trade and the connection of the world, there is a fast-growing development of commercial vehicles which ensure transport of various types of goods. That is why many types of superstructures for commercial vehicles specific to certain industries are being developed. This paper presents the development of a truck superstructure for transporting bulk cargo. At the beginning of the paper, the categorization of vehicles used for transporting goods is presented. Also, the laws and regulations considering dimensions, mass and wheelbase of commercial vehicles are presented. Furthermore, the requirements and instructions from the manufacturer of the selected truck on which the superstructure is installed are presented. Therefore, a list of criteria that the superstructure needs to meet was made. The criteria were then used for the conceptual phase of three concepts which were evaluated according to the chosen criteria. The development phase starts with the choice of a vehicle and the chassis, and it is continued with the design of the subframe and the truck bed (frame and sideboards) and the design of the joints between the chassis and the subframe. Stress analysis of the subframe and the truck bed supports is presented. Calculation of the axle loads is also presented. The calculation of the hydraulic cylinder is presented for three critical cases (start of the bed tipping, sideways tipping and rear tipping). Afterwards, hydraulic cylinder used for bed tipping was selected and the final truck maximal load was calculated. Finally, a 3D model of the superstructure for transporting bulk cargo was made with the following technical documentation.

Cilj ovog rada je kreiranje realnog mehanizma za upravljanje stražnjim kotačima bolida Formule student. Kako bi se razumjele prednosti uvođenja zakretanja stražnjim kotačima potrebno je razumjeti osnove lateralne dinamike vozila. Jedan od glavnih faktora kod analize lateralne dinamike vozila je pneumatik. Iz tog razloga nužno je poznavanje osnovnih pojava vezanih uz pneumatike. U radu će prvo biti objašnjene sve pojave koje su vezane uz pneumatike, a odnose se na lateralno gibanje vozila. Nakon toga biti će objašnjena lateralna dinamika vozila. Nakon teoretskog objašnjenja pojmova vezanih za uvođenje stražnjeg sustava upravljanja potrebno je proučiti mehanizam upravljanja. Iz tog razloga provedena je analiza svih dosadašnjih rješenja vezanih uz upravljanje sa stražnjim kotačima. Nakon provedene analize određeni su zahtjevi koje sustav upravljanja mora zadovoljiti te su uz njih određeni i kriteriji za vrednovanje koncepata. Nakon toga kreirani su koncepti za sustav upravljanja stražnjim kotačima bolida Formule student. Svaki koncept je osmišljen te je izrađen u 3d obliku s pomoću specijaliziranog alata za 3d modeliranje Solidworks. Također, provedeni su i okvirni proračuni za svaki koncept kako bi koncepti bili što realnije dimenzionirani. Nakon što su kreirani svi koncepti potrebno je provesti dinamičku analiza bolida, radi vrednovanja koncepata. Prije provođenja analize kreirane su ispitne procedure prilagođene bolidu Formule student. Analiza dinamike bolida provedena je u programu AVL-VSM. Nakon provedenih simulacija bilo je potrebno analizirati dobivene podatke, a za to je korišten program AVL Concerto. Na kraju provedeno je završno vrednovanje koncepata te je odabran najbolji koncept prema prije određenim kriterijima. Odabrani koncept je dorađen te je za njega izrađen sklopni crtež. The purpose of this thesis is to create a realistic design of rear wheel steering for Formula student car. To understand the benefits that can be obtained by implementing the rear wheel steering it is necessary to understand the basics of vehicle lateral dynamics. One of the main factors in vehicle dynamic analysis is the tyre. Therefore, it is crucial to understand the basic terms related to the tyre. In this thesis, all the tyre parameters related to the lateral dynamics of the vehicle will be explained first. After that the lateral dynamics of the vehicle will be explained. The next step, after all the necessary concepts for understanding the benefits of rear wheel steering implementation have been explained, is to analyse the rear wheel steering mechanism. An analysis of all previous solutions related to rear wheel steering in vehicles has been carried out. After the analysis, the crucial requirements regarding the rear wheel steering were determined. In addition to the requirements, the evaluation parameters for the concepts were also determined. The next step was designing and modelling of the rear wheel steering concepts for Formula student vehicle. All the concepts were created using a 3d modelling tool Solidworks. In order to create realistic concepts, the basic calculations of the components were carried out. After that the vehicle dynamics analysis can be carried out. Before the analysis the testing procedures adjusted for the Formula student vehicle were created. For the vehicle dynamic analysis, the program AVL-VSM was used. For the postprocessing of the results the program AVL Concerto was used. For the conclusion of the thesis, the final concept evaluation was carried out using the predetermined evaluation parameters. The selected concept was further developed, and the assembly drawings were created.

U ovom je radu prikazan razvoj sklopa kotača s integriranim pogonom za Formula Student bolid RT07. Prvi korak je bila analiza prednosti i nedostataka konceptualnih rješenja sklopa kotača u svrhu odabira prikladnog rješenja. S obzirom na geometrijska ograničenja generirano je nekoliko koncepata. Ti koncepti su uspoređeni prema zadanim kriterijima te je odabran jedan koncept koji je detaljnije razvijen. Za odabrani koncept su provedeni analitički proračuni za komponente poput vijaka, svornjaka, ležajeva i glavčine. Uz rad je priložena tehnička dokumentacija razrađenog koncepta sklopa kotača s integriranim pogonom koja uključuje sklopni crtež i radioničke crteže pozicija sklopa kotača. In this thesis, in-wheel motor concept development for a Formula Student vehicle RT07 is shown. Firstly, advantages and disdvantages of in-wheel motor concepts are analysed in order to select suitable solution. Secondly, with respect to the geometric limitations few concepts were generated. Those concepts are then compared according to the given criteria and one is chosen for further development. For the chosen concept, analytical calculations for components such as bolts, pins, bearing and wheel hub are performed. The thesis is accompanied by technical documentation of the elaborated in- wheel motor concept which includes assembly drawings and engineering drawings of the wheel assembly parts.

Deformacija ovjesa pri vožnji trkaćeg automobila makadamom dovela je do potrebe revizije njegovih postojećih elemenata. Prvi korak ovog diplomskog rada bio je razlučiti realnu mogućnost dolaska do opterećenja koje će dovesti do takve deformacije od potencijalne iznimke koju nije moguće generalizirati. Proučavanjem literature te provedenim analizama potvrđena je stvarna vjerojatnost ponovnog dolaska do neispravnosti tj. do plastične deformacije koja nije uzrok zamora. Numeričkim analizama (u kombinaciji s nezanemarivim iskustvom) napravljen je redizajn kritične komponente te je ispravnost potvrđena za veći spektar mogućih opterećenja. Driving racing cars on macadam roads leads to suspension deformation. This calls for revision of its existing elements. The first step in this work was to distinguish the potential possibility of occuring such load that will lead to this kind of deformation of a potential exception that cannot be generalized. By studying literature and the analyzes carried out, the realistic probability of failure reappearance, i.e. plastic deformation, which is not the cause of fatigue is confirmed. Using numerical analyzes (coupled with negligible experience) critical component redesign has been made and the validity is confirmed for bigger specter of possible load scenarios.

Ovim radom napravljen je pregled uobičajenih izvedbi samoutovarnih traktorskih prikolica za drvene trupce tehničke kategorije R3 (zbroj najvećih tehnički dopuštenih osovinskih opterećenja prelazi 4500 kg, ali ne prelazi 21000 kg). Zatim smo definirali listu zahtjeva za samoutovarnu prikolicu i odabrani su projektni parametri zasnovani na analizi postojećih rješenja. Odabrano je najprikladnije rješenje prema kriterijima koji se odnose na eksploatacijske značajke, pouzdanost i proizvodnu cijenu. Samoutovarne traktorske prikolice su danas jedan od standardnih alata u eksploataciji šumskog dobra. Glavna namjena im je transport drvenih trupaca s mjesta sječe do stovarišnog mjesta koja služe kao međuskladište sirovine (drvenih trupaca) prije transporta do mjesta konačne prerade. Da bi se takvim specijaliziranim prikolicama mogao vršiti transport po teškom šumskom terenu ovi radom prikolica je dimenzionirana tako da su okvir i podvozje (osovine) robusne izvedbe i omogućuju dobro praćenje podloge po kojoj se vozni slog kreće (traktor i prikolica). Kako bi se povećala pokretljivost voznog sloga, na prikolicu je ugrađen dodatni pogonski sustav koji omogućuje da se po potrebi poveća broj pogonskih osovina voznog sloga. Odabrana varijanta rješenja je razrađena, te je izrađena tehnička dokumentacija. In this thesis, a review of commonly designed self-loading tractor trailers for wooden logs in R3 technical classes (the sum of technically maximum permissible loads lies between 4500 and 12000 kg) has been represented. Afterwards, a list of demands for the self-loading tractor trailer has been defined altogether with chosen project parameters based on analysis of the existing solutions. Taking into the account criteria such as exploitation features, reliability and production cost, the most suitable solution has been chosen. Self-loading tractor trailers are nowadays one of the standard tools used in exploitation of forest goods. Their main purpose is the transport of wooden logs from harvesting location to warehouse location which is used as intermediate storage (of wooden logs) before transport to the location of the final processing stage. In order to complete a successful transportation on heavy forest ground with these specialized trailers, the trailer in this thesis is dimensioned in a way that the frame and chassis are robust and therefore enabling good tracking of the surface on which the assembly (tractor and the trailer) is moving. In order to achieve an increased movability of the assembly, an additional powertrain has been implemented in the design of the trailer which enables an additional number of shafts in the system, if necessary. The selected version of the solution has been elaborated and the supporting technical documentation has been presented.

U Laboratoriju za motore i vozila na Fakultetu strojarstva i brodogradnje nalazi se kočnica Zöllner tip VA-100 AC DAM 4 RS za ispitivanje malih motora s unutarnjim izgaranjem. Trenutačno postolje kočnice Zöllner ne omogućuje prihvat širokoga raspona dimenzija motora te ne omogućuje podešavanje ispitivanog motora u prostoru. Cilj zadatka je promjena konstrukcije postolja kočnice i omogućavanje preciznog podešavanja i pozicioniranja postolja kako bi ono moglo prihvatiti ispitivane motore različitih dimenzija i veličina. U prvom dijelu rada definirao se i opisao zadani problem, te su se dale osnovne informacije o procesu ispitivanja motora s unutarnjim izgaranjem na ispitnim kočnicama. Zatim dao se pregled vrsta kočnica za ispitivanje motora te se opisao način njihova funkcioniranja. Nakon toga opisana je kočnica Zöllner te se prikazao njen presjek sa dijelovima. U drugom dijelu sakupili su se svi zahtjevi potrebi za određivanje parametara konstrukcije. Istraživanjem tržišta i prikupljanjem podataka određeni su najčešći i najpoznatiji motori s unutarnjim izgaranje predviđeni za ispitivanje na kočnici. Izmjerene su njihove dimenzije koje bitno utječu na konstrukciju postolja te je određen njihov raspon od najmanjih do najvećih. Zatim su se definirali dodatni zahtjevi, te se je izmjerio trenutačni sklop kočnice s ispitnim stolom. Dodatno predstavili su se pojedini koncepti te se odabrao koncept koji je najbolje odgovarao zahtjevima. U trećem dijelu nakon što se odabrao koncept, pristupilo se razradi istoga te su se provele preinake i poboljšanja. U radu je predstavljeno konačno ponuđeno rješenje te je opisan način funkcioniranja i podešavanja konstrukcije. Prikazani su svi dijelovi konstrukcije, te je slikama predočen razvoj konstrukcije. Također proveden je kontrolni proračun elemenata konstrukcije, a uz pomoć metode konačnih elemenata programskim paketima Abaqus i FEMAP / NASTRAN provedena je kontrola glavne ploče te je određeno nekoliko prvih prirodnih frekvencija glavne ploče. U sklopu rada nacrtani su CAD modeli te je izrađena tehnička dokumentacija rješenja.