ZAZ Tavria baasil loodud ralliauto jahutussüsteemi konstrueerimine

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2017

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Tallinna Tehnikakõrgkool

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Lõputöö ülesandeks oli konstrueerida ZAZ Tavria baasil loodud ralliautole jahutussüssteem ning selleks oli vaja täita erinevad ülesanded. Autole oli vajalik kinnitada jahutustorustik nii põhisüsteemi jaoks kui ka soojendusradiaatorile. Veenduda oli vaja, et torustik teistele seadmetele ette ei jääks ega liigselt sõidu ajal ei liiguks, mille jaoks sai paigaldatud torusi paigalhoidvaid klambreid. Autole oli vaja disainida ja kinnitada paisupaak. Paisupaagi minimaalne suuruss tulenes süsteemi kogumahu ning töötemperatuuri vahelisest seosest. Paisupaagile kinnitus süsteemi survestav survekork ning lisaks valmis paisupaaki kandev alus. Kuna tegu on keskmootoriga autoga, oli vajalik töötada välja süsteemi õhutussüsteem. Selleks sai paigaldatud vastav õhutusventiil radiaatori külge. Kontrollitud sai soojusvaheti efektiivsust. Kuigi esmalt läbi viidud arvutustele tugiedes näis radiaator sobivat, selgus pärasst korrektuuride tegemist, et soojusvaheti pole piisavalt efektiivne tulevase modifitseeritud VAZ mootori jaoks. Selleks ajaks oli ka õhutussüsteem välja töötatud, kuid see on vajadusel võimalik kinnitada teise, efektiivsema radiaatori külge. Ka sai arvutatud veepumba vajalik efektiivsus. Seda ületab VAZ mootori originaalpump piisavalt ning see läheb kasutusse. Termostaadi puhul sai võimalikke alternatiive uuritud. Siiski saab kasutatav termostaat olema samuti VAZ mootori originaal.


The following thesis is entitled The Construction of an Engine Cooling System for ZAZ Tavria Based Rally Car. ZAZ is an Ukraine based automobile manufacturer, which was known for the small production cars during the existence of the Soviet Union. ZAZ offered the cheapest entry-level economy cars in the country. The first two mass production models 965 and 968 were equipped with an air-cooled rear mounted engine. In 1987, after 27 years since the production of cars had started, a new model called Tavria was launched. Tavria was one of the USSR’s front-wheel driven relatively modern hatchbacks, alongside with bigger Lada Samara and Moskvich Aleko. The Tavria model became a basis for the Estonian built rally car which underwent major changes compared to the original. The original engine was replaced by a Lada 1600 cc unit and the engine was now mounted in the rear part of the vehicle. By doing so, the car was converted to rear wheel drive. The bodywork was covered with carbon fiber panels to resemble the infamous B group rally cars. Altogether three similar cars were produced. After suffering years of neglect, one of the remaining cars has found its way to the TTK University of Apllied Sciences where the restoration is in progress. When eventually completed, the car will be handed over to the Estonian Motorsport Museum. Like many other componenets and subsystems of the vehicle, the cooling system had to be constructed from the ground up. Since the engine is a rear mounted Lada unit, custom pipework had to be made, in order to get the coolant flowing to the front mounted radiator. The same goes for the heater unit where also long copper tubes lead the coolant to the interior and eventually to the heater radiator. Since the radiator is quite far from the engine and the coolant passes the underside of the car, the threat of air getting trapped in the system becomes greater. Therefore the bleeding system was attached. The radiator was equipped with a bleed valve which can be opened during the initial system fill and by doing so, the air will be bled. During the later phase of the thesis, when the calculations for the heat exchanger unit were corrected, it became apparent that the radiator is not efficient enough to handle the amount of heat produced by the modified Lada engine, which is going to produce presumably 90 kW of power. The bleeding system had been welded already to the radiator. However, it can be removed and welded again to the new exchanger. An assignment to design and fabricate a custom expansion tank was given. The custom expansion tank received a pressure cap in order to pressurise the cooling system which helps to increase the boiling point of the coolant. The expansion tank was crafted from aluminium. A lathe was used to craft the pipes to attach hoses, which were later welded to the tank. Also the neck for the pressure cap had to be machined. The unorthodox M50x3 thread was also cut by lathe after carefully adjusting the machine. The aluminium had to be TIG welded because of the material properties. The minimal size of the tank was calculated according to an empirical relation between the operating temperature and the necessary percent to the overall cooling system volume which defined the size of the tank. Additionally, the research for the alternatives of the original thermostate and waterpump was carried out, but neither was replaced. In concluson, after carrying out a lot of research and practical work, the car should have a fully functioning cooling system. However, a proper replacement heat exhanger must be added.

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