Nauèno-tehnièki PREGLED,Vol

HE 19th International Conference with Exhibition ²Science and Motor Vehicles², was held in Belgrade, 26-28 May 2003, in the Inter-Continental Hotel. It was dedicated to ²Automotive engineering for intelligent vehicle systems², and gathered a large number of native and foreigner experts. The conference was organized by the JUMV – Yugoslav Society of Automotive Engineers, under the patronage of the FISITA – International Federation of Automotive Engineers Societies, the EAEC - European Cooperation of Automotive Engineers, and the SANU – Serbian Academy of Science and Art. Professor Dr. Čedomir Duboka, JUMV President, opened the Conference, and messages to the Conference were delivered by Mr. Philippe Marcangeli, FISITA Vice President for Europe and Dr. Pedro de Esteban, EAEC President.

The introductory presentations were given by Dr. Habil Egon-Christian von Glasner (DaimlerChrysler,D), Professor Dr. Jovan Todorović (Honary President of the JUMV), and Professor Dr. Dušan Gruden (Porsche,D).

The conference was organized through two parallel sessions: “Conference in English”, and “Conference in Serbian”. There were 36 papers for the English Conference, and 14 papers in Serbian. The participating experts were from about ten European countries (France, Germany, Italy, Austria, Slovenia, Czech Republic, Slovakia, Hungary, Romania and Greece). The Conference in Serbian had less pariticipants. The authors of papers were from industrial organizations, scientific institutes, technical faculties and the Military Academy.

The presentations concerned active safety, which is of the greatest interest nowadays, braking systems, electronic controllers more and more present in all vehicle elements and systems, steering systems, suspension systems, combustion of fuels, exhaust emission, etc.

Respecting a wide scope of problem addressed and a great number of presented papers at the Conference, here will be presented the most important and most interesting papers from sessions, that could be of interes for the Military-Technical Review readers.

– ACTIVE SAFETY OF COMMERCIAL VEHICLES – STATUS 2003 – Dr. R. Povel, Prof. Dr. Habil. E.–C. von Glasner, Daimler Chrysler, Germany

This paper, presented at the Conference Opening, describes the aims of vehicle industry development. Permanently increasing competitive and legal requirements demand the exploitation of all technological and engineering possibilities. The high standard of commercial vehicle technology now attained in all safety aspects means that new ways must be found to utilize the remaining scope for further progress in optimizing mechanical systems by increased application of electronics. These mechatronic systems will further assist and relieve the driver of stress, and will contribute to improve active and passive safety as well as transport efficiency. Intelligent technologies offer further potential to open a new dimension for road traffic in terms of safety, economy and environmental compatibility.

Another objective in this process is to improve all these safety-related systems at the best possible costs, thereby increasing the overall economy of commercial vehicles as well.

– CO₂ – NEUTRAL WAYS TO ENSURE FUTURE MOBILITY – Prof. D. Gruden, Porsche A. G., Germany

This paper was presented in the opening program of the Conference, and refers to new power sources, a problem that more and more scientists are occupied with nowadays.

Our highly industrialized world mostly uses fossil-energy raw materials for its smooth functioning. Two complete end products of fossil fuel combustion, CO₂and H₂O, count among the so-called trace gases in the atmosphere, which are contributing to the greenhouse effect. In contemporary researches biomass proves to be an excellent raw material for the production of efficient fuels, such as alcohols and vegetable oils. In the light of discussion on the „protection of the atmosphere“ the greatest advantage of biogenous fuels is their neutral CO₂ balance. Researches are expected to find out whether photosynthesis and biomass actually are a practical way of guaranteeing the energy supply in the future. Activities of finding a new energy supply for the future are a part of an evolutionary process which can be summarized as follows:

„Man must learn how to produce his own energy just as he learnt to produce his own food“.

– PRODUCTION OF NEW ECOTEC ENGINES AT THE KAISERSLAUTERN PLANT – Dr. J. Quarg, FIAT GM Powertrain, Germany

This paper presented a new ECOTEC L4 engine family that covers a displacement range of 1.8 up to 2.4 liters. The ECOTEC engine all in aluminum represents the latest technology and ensures high performance in all vehicle lines where it is installed (for Opel these are: Astra, Zafira, Speedster, Vectra).

It features the DOHC 4 valve design of the cylinderhead with chain-driven camshafts as well as hydraulic lifters with roller finger followers. The cylinderblock is a lightweight aluminium casting with a bedplate and incorporated balance shafts. After a brief product presentation this paper describes the production equipment in Kaiserslautern with about 42 transferlines, 149 single machines, the specific processes and the quality management.

– ENVIRONMENTAL – FRIENDLY AIR – CONDITIO-NING FOR AUTOMOTIVE APPLICATION – Dr. S. Ćućuz, T. Pawelski BSc, Visteon Climate Control Systems, Germany

Since the environmental aspects are of increased importance today, the automotive industry is developing environmental friendly mobile air conditioning systems. This paper presents a Visteon developed a/c system using CO₂ (R744) that offers efficiency benefits and additional comfort, compared to other previously used refrigerators. As the thermodynamic processes of currently produced air-conditioning systems and the a/c system using the environmental-friendly refrigerant CO₂ (R744) are different, changed components are presented. The basic system structure remains the same.

Possible system architectures including the heat pump cycle, investigated by Visteon, were-presented also presented. Due to the higher pressures of the transcritical CO₂ cycle, the design requirements for the system components changed and new control algorithms are needed. The test results from the vehicle tests with a/c as well as with heat pump systems, proved the potential of CO₂ as a future refrigerant for mobile air conditioning systems.

– ELECTRONIC AIR CONTROL – AIR TREATMENT AND DISTRIBUTION IN A COMPRESSED AIR BRAKING SYSTEM – P. Jennison, E. Hilbere, Knorr–Bremse SfN, Germany

As it has been said, in all vehicle systems more and more electronic components are used to control processes in a vehicle. In a compressed air braking system for commercial vehicles the distribution of the compressed air for storage, the pressure at which it is stored and the quality of the air in terms of its cleanness and dryness is of paramount importance. Traditionally, this has been achieved using a number of individual components – unloader or governor, air dryer, multi-circuit protection valve – which over a period of time have been integrated with each other. Now with the “Electronic Air Control” (EAC) device, the multi-circuit protection valve function has been fully integrated. Based on entry values, it gives Pressure information, EAC – status, Engine Speed Demand and Diagnostic Information. The functional process is based on the CAN protocol. This paper presents the disposition of the whole system and the characteristics of the EAC device.

– ELECTRONIC STABILITY PROGRAM (ESP) FOR COMMERCIAL VEHICLES – Dr. L. Straub, Knorr–Bremse SfN, Germany

This paper presents a new Electronic Stability-Program for Commercial Vehicles (ESP) The ESP is a safety system used to assist the driver in critical situations like: skidding, jackknifing and rolling over. The ESP improves steerability and controllability, avoids jackknifing and reduces the danger of rolling over. It incorporates the Electronic Brake System EBS (main features are: pressure modulation individually by wheels or axles (modular design, adaptable to all vehicle combinations), electronic transmission of brake demand (driver or other) via CAN (Controller Area Network) to individual wheels and the trailer, pneumatic backup, better brake response (braking sensitivity like in passenger cars), electronically controlled load sensing and brake force balancing, antilock brake system ABS, traction control system TCS, coupling force control CFC for better brake compatibility between the tractor and the trailer, lining wear control for longer service intervals and retarder integration.

The disposition of the whole system is presented. The production of ESP for commercial vehicles is believed to significantly increase traffic safety.

– THERMAL STRESSES IN OIL IMMERSED MULTIPLATE CLUTCHES AND BRAKES – D. Lazarević, dr Z. Živanović, VTI, Belgrade, Serbia & Montenegro

This paper presents researching of thermal stresses on frictional surfaces which occur under thermal load. During the friction elements running, great quantity of heat has been produced on frictional surfaces. If thermal load exceeds limited values, it can cause significant problems during their operation.

Here are presented the results of the theoretical analyses, obtained by solving a complex system of mathematical equations, experimental tests carried out on the test stand PSS-51, advantages and disadvantages of both approaches. At the end, the possibility of thermal stresses research by using modern program packs, such as Pro/Engineer, was shown. It enables the simulation of the sliding process on friction discs and obtaining an overall view of thermal stresses levels.

– A NON–LINEAR CONTROL FOR THE YAW STABILIZATION OF VEHICLES – S. A. Karabachos, Professor Dr. K. N. Spentz as, National Technical University of Athens, Greece

This paper proposes a non-linear control system to improve vehicle handling and stability under severe driving conditions by actively controlling the front steering angle (2WS). For that purpose a mathematical model of a vehicle was made. Here are presented the results of analyses obtained by varying entry parameters: vehicle speed, steering angles and wind distribution, and the influence of these factors was investigated.

– A NEW CONCEPTION OF THE TRANSMISSION CONTROL SYSTEM WITH TWO PLANETARY GEARS FOR HIGH SPEED TRACKED VEHICLE – Dr Z. Živanović, G. Jerkin, VTI, Belgrade, Serbia & Montenegro

This paper presents a new realized transmission control system concept for high-speed tracked vehicles with two planetary gearboxes, named GC TRONIC. It is based on using electrohydraulic parts and the microcontroller as an electronic control device. The automatic and controlled gear change process under load is provided, without using the main clutch except for the start. The basic information about this system are given as well as the gear change output characteristics. The results are obtained on the test stand with a real transmission.

– DYNAMIC SIMULATION OF BEHAVIOR OF A “LIGHT VEHICLE” FOR DISABLED USERS TESTED ON A VIRTUAL ROAD – S. De Gaetano, G. Guerrera, Prof. G. V. Mariotti, University of Palermo, Italy

This paper presents the numerical simulation of the behavior on the road of a light vehicle with a disabled user. It begins with the examination of the suspension geometry and of the characteristic wheel angles. During the first simulation phase the damper optimization is executed: a vehicle is schematized like a suspended mass acting on the ground by four non-suspended masses, including the wheels and the suspension. Three different vehicles have been tested on this virtual route, each of them equipped with a particular damping constant. The second simulation phase has the purpose to test the vehicle reaction to the virtual driver maneuvers (Alce test with modifications). It allows modifications of some suspension parameters, offering the chance of testing the differences on the virtual track. The tested vehicles are equipped with two different geometrical configurations with different damping coefficients. Hence the wheel-ground reactions are determined and the torsion rigidity analysis is executed.

– A CONTRIBUTION TO AN ANALYSIS OF THE INFLUENCE OF THE STEERING SYSTEM TYPE ON BUS DYNAMIC PARAMETERS – Professor Dr. M. Demic, University of Kragujevac, Dr. Dj. Diligenski, INNI Vinca, Serbia & Montenegro

Contemporary motor vehicles, especially buses, are most commonly equipped with power steering, having a hydraulically powered steering as a standard option. Since the type of steering influences most of bus motion parameters, particularly handling parameters, this paper deals with the model of a bus with both power and classical (mechanical) steering. The model enables complex analyses of the influence of the steering type on bus motion parameters.

– VIRTUAL TESTING OF PLANETARY GEARS – S. Muždeka MSc, Military Academy, Professor Dr. Ž. Arsenić, University of Belgrade, Dr. Z. Popović, M. Krsmanović BSc, Military Academy, Belgrade

This paper presents the simulation of a planetary gear virtual model and the conditions for modeling a real gear work process, as well as conditions for the realization of virtual tests of complex gears. The ways of simulating power engagement to overcome resistance in the gear functioning are defined for a planetary row with one degree of freedom. The simulation results showed a high level of agreement with theoretical methods for determining efficiency of planetary gears, thus pointing out a possibility to apply virtual testing in the development process.

– ANALYSIS OF THE TRANSMISSION RATIO AND TRANSMISSION EFFICIENCY IN TRANSMISIONS WITH HYDROSTATIC TRANSFORMATIONS OF KINEMATIC AND DYNAMIC PARAMETERS AND THEIR OPTIMIZATION BY THE RECIRCULATION METHOD – Dr. Z. Popović, Military Academy, Beograd, Professor Dr. S. Milidrag, FTN, Novi Sad, V. Blagojević MSc, VRS, Bjeljina

This paper presents an analysis of losses, transmission ratio and efficiencies of hydrostatic transmissions. Hydrostatic transmission covers a wide range of mobil systems such as caterpillar vehicles, agricultural machinery and coal mining equipment, machine tool drives etc. These transmissions are characterized by series of favorable attributes: continual transformation of dynamic and kinematic parameters, easy steering vehicle, etc. The main disadvantage of these transmissions is their low overall efficiency under operating conditions. An original idea (and the experimental results) of an asymmetric transmission of the hydraulic fluid is presented here in order to optimize the values of these parameters.

– EXPERIMENTAL DETERMINATION OF IC ENGINE MECHANICAL LOSSES – Z. Građin MSc, TOC, Professor Dr. M. Tomić, University of Belgrade , D. Đurica BSc, TOC, Beograd

This paper presents an investigation of IC engine mechanical losses that has always been a rather hard task, since their exact experimental determination is complicated and often inaccurate because the IC engine is a thermal machine and not a simple tribo-system. There are several methods for IC engine mechanical losses measuring. These methods are: Engine external powering (external motoring), Morse test (for multi-cylinder engines), Willans line method and Engine indicating method (incylinder pressure record and indicated mean effective pressure calculation). All of these methods have some advantages and disadvantages. The goal of this paper is to compare the results of mechanical losses measured by all these methods applied to a four stroke, four cylinder DI diesel engine with the swept volume of 4.07 l. In order to determine the overall mechanical losses distribution and the fraction of particular components losses, the method of gradual engine parts and aggregates removal (disassembling) has been applied. The results of the experimental investigation are given as power losses and the mean friction pressure as a function of the engine speed. The paper also presents the particular mechanical losses analysis and the discussion of their distribution with the comparison of all applied methods.

– REVITALIZATION OF 1.4 L. DMB ENGINE –Tadija Jurković BSc, OPEL ITDC, Russelsheim, Germany, Professor Dr Stojan Petrović , Professor Dr. Miroljub Tomić, University of Belgrade, Ćupurdija Aleksandar BSc, Šime Uremović BSc, DMB Engine Factory, Belgrade, Serbia & Montenegro

The paper presents research work carried out with the main goal to innovate the existing standard 1.4-liter DMB gasoline engine. A number of modifications have been applied to improve engine quality and performances. The main modifications are: optimized gasoline injection system, new intake manifold, new camshaft material, modified valve gear with new valves, springs and hydraulic tappet, improved sealing, etc. The innovated engine has 59 kW maximum power (20% higher than the standard engine) and 112 Nm maximum torque at full engine load, as well as almost 20 % lower minimum specific fuel consumption at partial load.

– INVESTIGATION INTO THE EFFECT OF EGR ON THE MACRO CHARACTERISTICS OF DIESEL COMBUSTION – A. Hribernik BSc, Ž. Dobovišek BSc, N. Samec BSc, G. Bombek BSc, University of Maribor, Slovenia

This paper describes exhaust gas recirculation (EGR) that is used for NOx emission reduction. Researchers have observed 30 % to 75 % reductions in NOx when using 5 % to 25 % EGR rates. Although there has been extensive experimental research on emission formation by the application of EGR, little has been devoted to the Diesel combustion process. An attempt was made to study experimentally the combustion process at different EGR rates and engine loads. A heavy duty 4-cylinder 7.2 liter turbocharged Diesel engine was used for the tests and a low pressure EGR concept was applied where the EGR rate was controlled by an EGR valve. In-cylinder pressure traces were measured and analyzed. An one-zone combustion model was used to compute the rate of heat release from the experimental results. Several combustion parameters such as ignition delay, duration of pre-mixed and diffusion flame, combustion duration, etc., were determined and carefully studied, and the basic correlation is presented and discussed.

– MATHEMATICAL OPTIMIZATION OF 1.4L PET-ROL ENGINE EXHAUST MANIFOLD – M. Ćertić BSc, Professor Dr. M. Tomic, University of Belgrade, Serbia & Montenegro

This paper presents the results of spark ignition engine exhaust system optimization, performed using the 1-D computer simulation model. The improvement of engine output has been achieved by the variation of engine exhaust system geometrical parameters. The methodology for large amount of output data evaluation has been developed as well as additional criteria for optimal solution determination. Mutual interference of particular elements was investigated and used to improve the overall engine performance. The results are compared with a simplified acoustic model for resonance frequency and wavelength calculations.

– REDUCTION OF INTAKE VALVE DEPOSITS USING GASOLINE ADDITIVE – Dr. D. Nestorovic, Zastava Institute for Cars, Kragujevac, Professor Dr. M. Radovanovic, Dr. D. Stoiljkovic–Simic, V. Jovanovic BSc, University of Belgrade, I. Gencic BSc, Oil Refinery Pančevo, Serbia & Montenegro, S. Bratschkow BSc, BASF, Germany

This paper presents Keropur®, one of the BASF modern additive packages, consisting of the detergent Kerocom PIBA, corrosion inhibitor, demulsifier and carrier fluid. The Oil Refinery Pančevo supplied the gasoline and the tests were made by the Zastava Automobiles - Automotive Institute and the Faculty of Mechanical Engineering - Fuels&Combustion Lab. The investigations of Keropur® with Yugoslav gasoline were carried according to the modified CEC F-04-A-87 method.

The motor 128A6.064 (DMB production) was chosen for the investigation as being similar to the motor OPEL Kadett12 S used in the original CEC test. The tests were performed with leaded and unleaded gasoline, with and without the Keropur® additive. The deposits were evaluated through the weight measuring and the Opel Kadett valve deposit merit rating scale. The obtained results have shown great reduction in deposits formation on the intake valve according to both evaluation criteria: weight measuring and the Opel Kadett valve deposit merit rating scale.

– ANALYSIS OF WORKING TEMPERATURES OF FLORIDA`S 1.3i THREE COMPONENT CATALYTIC CONVERTER –M. Grubiša MSc, Dr. D. Nestorović, FAZ – Institute for Cars, Kragujevac

The construction of Florida 1.3i three component catalytic converter was shown and the working temperatures inside the catalytic converter realized during the driving test were measured.

The catalytic converter is used since strict requirements regarding the emission of poisonous gases from the gasoline engines cannot be satisfied even by the most modern engines, so it is necessary to implement additional processing of the exhaust gases. The most commonly used are catalytic converters mounted onto the engine exhaust system. This paper presents the three component catalytic converter produced in the Zastava Car Factory and built in Florida 1.3i. The efficiency of converting harmful gases in catalytic converters of passenger cars is based on the physical and chemical processes, their most important factors being content of the fuel mixture and temperatures inside the catalytic converters, i.e. the content of the exhaust gases at the engine outlet and their temperatures.

Beside the presentations of the submitted papers, the program of the Conference included the presentation of WABCO-Austria and the seminar on the accreditation in the organization of the JUAT (Yugoslav Association for Accreditation).

The 19th International Conference with Exhibition ²Science and Motor Vehicles² can be characterized as very successful, judging by the quality and diversity of presented papers that covered all motor and vehicle systems and by a good organization of the whole Conference. This Conference is the most important one of that kind in our country and the whole region. The proceedings (on a CD) are available at the Library of the Military Technical Institute.

Received: 27.7.2003

[1]⁾ Military Technical Institute (VTI), Katanićeva 15, 11000 Beograd

19th International conference „Science and motor vehicles”

19^th International conference „Science and motor vehicles”