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Provision of a layer of zinc on aluminium to provide the fillets for soldering is well established but this usually necessitates a thick layer of zinc (>30μm) and soldering at temperatures below 450°C. New technology has been developed to enable sound joints to be made on aluminium heat exchangers using a much thinner layer of zinc (4 to 8 μm typically) on the aluminium component to provide the joint. By the correct combination of flux and zinc coating thickness, joints have been obtained over a wide range of heating conditions. Preferred temperature cycles are similar to those used by the industry today for brazing of Aluminium:Silicon braze-clad aluminium components which should facilitate tranfer by industry to the new technology.

An approach to evaluating and optimizing the vehicle engine cooling system design for minimum total vehicle cost is presented. This approach examines direct cooling system component plus the related costs for the rest of the vehicle, such as power consumption and weight, and intangible costs such as noise and vibration that affect the perceived quality of the car. It relies on computer modeling of the cooling system in order to evaluate system design variations in the advance vehicle development stage, before the overall car design is fixed. Examples of the cooling system optimization process are presented for typical passenger cars.

An evaporator which is one of important components of the automobile air conditioning system has been developed on the view point of increasing heat transfer coefficient and decreasing fluid pressure loss. To employ new configuration of refrigerant side heat transfer tube surface could improve heat transfer coefficient by 2.6 times of smooth surface heat transfer coefficient. A distribution adjustment pipe and optimized arrangement of heat transfer tubes were applied to achieve uniform refrigerant flow distribution. We tried to minimize the increase of refrigerant side pressure caused by employing turbulizers inside the heat transfer tubes. We studied on thermo-fluidic behavior experimentally and developed new high performance evaporator.

This paper describes a method of predicting cooling performance in order to obtain the optimum design of the cooling system and front-end shape in the early stage of car development. This method consists of four calculation parts: thermal load on the cooling system, air flow through the engine compartment, heat dissipation by the heat exchangers and temperature distribution within the cooling system. It outputs the coolant, engine oil, automatic transmission fluid (A.T.F.) and charge air temperatures in exchange for the input of several car, power plant, drive train, exterior shape and cooling system specifications. For the calculations, in addition to theoretical formulas, several experimental formulas are introduced. This method verification is shown by presenting a few test cases for the respective calculation parts and the final solution.

A highly corrosion resistant drawn cup type evaporator was developed. During the development of this evaporator, the corrosion characteristics of evaporators in the field were examined in detail. Profound understanding of the corrosion mechanism led to the development of a new, unique, corrosion test method which simulates the actual evaporator field service environment. The main factors involved in increasing the corrosion resistance of the brazing sheet are (1) reduction of iron and silicon content in the core alloy and, (2) addition of titanium to the core alloy. In the present alloy, titanium content varies lamellarly through the thickness of the core alloy. Regions of high titanium content have a more cathodic potential, thus causing corrosion to proceed along the low titanium content lamellae. Consequently, the reduced iron and silicon contents, and the titanium addition, have the net effect of reducing the pitting corrosion rate.

Extensive work was conducted to develop a corrosion resistant brazing sheet alloy and to apply it to a drawn cup type evaporator in automotive air conditioning system. The items to be investigated included the influence of chemical composition of the core alloy on corrosion resistance, suppression of erosion during the brazing cycle, and enhancement of the brazing sheet formability. Additional investigation was conducted to develop a new corrosion test method on the basis of better understanding of the mechanism of corrosion in the field and to evaluate the corrosion resistance of a evaporator fabricated from the new alloy. This paper, as Part 1, describes the results of alloy development from the metallurgical and electrochemical point of view.

Sequential four-ball wear tests have been used to evaluate automotive crankcase oils for use as heavy-duty hydraulic fluids and automotive crankcase lubricants. This test technique has been adapted for use with steel-on-steel, steel-on-ceramic and ceramic-on-ceramic bearing systems. In addition to the conventional “run in” and “steady-state” wear studies, the data produced have been used to interpret bearing unit load levels for the various bearing systems involved. The data produced show that in many cases hybrid bearing systems (steel-on-ceramic) and ceramic-on-ceramic bearing systems may be useful at higher unit loadings than the conventional steel-on-steel systems. These studies focused on achieving low boundary lubricated wear rates. The bearing unit loadings were obtained from the unit bearing pressures after the “run in” of the specific bearing system.

A master piston assembly has been developed for a heavy duty diesel engine compression brake to reduce sliding wear at an oil lubricated bearing steel counterface. The assembly, consisting of a medium carbon steel piston body and mechanically retained silicon nitride ceramic pad, is an economical alternative to a one piece tool steel piston.

Sintered silicon nitride, particularly in structural ceramics, has superior properties such as low weight, heat resistance, wear resistance, etc. It is already being applied to automobile engine parts such as the swirl chamber and the turbine rotor. In recent years, the strength of silicon nitride has shown to be above 1000MPa. This has been achieved through advances in manufacturing technology such as materials powder, forming, sintering and so on. But the silicon nitride is easily damaged during grinding because it has less fracture toughness than metal. Consequently, the inherent strength of the material is not demonstrated in the actual products presently produced. It is assumed that the main cause of strength reduction is microcrack. In ordinary grinding methods, the length of microcrack has been estimated at approximately twenty micrometers by fracture mechanics analysis.

The motorcycle emissions regulations for both two-stroke and four-stroke engines, which are receiving worldwide attention, will go into effect in the very near future. To meet these regulations, the motorcycles will require a catalyst in conjunction with the muffler due to space limitations. The combination of high engine speeds, high vibrational acceleration, high HC and CO emissions, high oxidation exotherms, and stringent durability requirements, points to cordierite ceramic substrate as an ideal catalyst support. However, as an integral unit within the muffler, its packaging design must be capable of withstanding isothermal operating conditions which may exceed the upper intumescent temperature limit of the ceramic mat. This paper describes a durable packaging design for the ceramic catalyst which employs a hybrid ceramic mat, special end rings and gaskets, and high strength stainless steel can.

A review of evaporator constructions, currently used in vehicular air-conditioning applications, is presented. An examination of the drawn cup (or laminated plate) and serpentine constructions is made followed by the introduction of a new construction, the PFE™ evaporator. This is followed by a comparison of relevant geometrical parameters and various thermal/hydraulic performance characteristics. Laboratory tests indicate that the PFE evaporator provides higher cooling capacity (heat transfer rate) per installed volume, lower air-side pressure drop and comparable water (condensed) shedding characteristics with a smaller installed depth than currently produced drawn cup and serpentine evaporators.

The POND RACER is an all-Composite, twin boom airplane Figure 1,(1), (2), (3), fitted with two, dual turbocharged automotive engines. The exhaust system, Figure 2, for this six cylinder power plant occupies the rear portion of a compact engine compartment. Initially, no provision was made for moving cooling air through this densely-packed engine compartment. Portions of the exhaust system passed within less than 2.5 cm (1 in.) of the composite cowl enclosing the engine compartment. The temperatures developed could result in failure of the computer,which controls the engine, other components, and the composite cowl in a matter of minutes. Currently-used insulation designs did not appear to provide enough capability to work for this application. A Thermal Protection System was developed, installed, and proven out during test flights. Analysis of the flight data, measured by thermocouples linked into the flight recorder, verified the adequacy of the Thermal Protection System.

Diesel ceramic coatings are now being applied to automotive engine components such as valves, pistons and heads to eliminate visible smoke, inhibit the formation of NOx, reduce CO and particulate emissions and improve combustion efficiency. Recently, specially designed software has been installed by trucking and transit companies to monitor the performance of the diesel ceramic coatings under actual operating conditions, with subsequent testing on EPA-certified dynamometers. The coatings are being evaluated for their ability to control particulate emissions (with and without particulate traps), for emissions in exhaust gases, for smoke, horsepower, speed in miles per hour, exhaust temperature and fuel rate in miles per gallon. These results, as well as the properties of the diesel ceramic coatings which effect these changes in diesel combustion, will be discussed.

A compact heat exchanger with cross and counterflow configuration is proposed to facilitate gas turbine installations suitable to small space available for conventional vehicular gas turbine engine envelopes. The invention is intended to advance vehicular gas turbine development programs world-wide. The concept is adaptable as an intercooler for turbo-supercharged Diesel engines. Low pressure ratio regenerative industrial and vehicular gas turbines have not reached mass production status because their heat exchanger construction either rotary (periodical) or recuperative (static) seems to be an unreliable and high cost component. The need exists to establish heat exchanger technology which will satisfy aerodynamic and heat transfer requirements of gas turbines and this is addressed in this paper.

An engineer, designing any given part, will always reach a stage where the specification of a material is required. For example, if parts consolidation or lighter weight is the criterion, injection moldable thermoplastic is often the material of choice. It remains necessary, however, to always satisfy the structural and thermal load requirements of a part. The selection of the right material can save considerable time and money. The choice is often difficult when the part needs to function in an environment that sees a combination of fatigue, creep or strength requirements due to various applied temperatures. A dilemma occurs when the engineer selects a material and fiber length based on limited published room temperature and short term properties. Material selection based on room temperature properties alone may be unsuitable at elevated temperature or under long term loading.

Recycling of advanced polymers and composites is a major problem facing the composites industry due not only to problems related to the actual process itself but also to liability issues associated with reuse. This paper presents the results of an investigation aimed at the reuse of waste pellets as aggregate in concrete to increase compression strength and ductility of the resulting concrete. A variety of glass filled materials including nylon, polycarbonate and polypropylene, as well as unreinforced polymers such as PET and PEEK, were used. Materials were substituted for traditional stone aggregate at a range of levels from 10 to 100%. Results demonstrate the viability of such use and the paper discusses implications in terms of future surface treatments.

A combination of factors, including the ability to tailor fabric architectures, has led to the recent resurgence of interest in glass fiber reinforced resin transfer molded composites for use in energy absorbing, impact resistant structures. In this paper we report the results of an investigation aimed at understanding the effects of fabric architecture on impact resistance with the end goal of designing suitable architectures. The damage process is described through the application of a series of instructive plots called elastic energy curves, which present significant insight into materials behavior. It is shown that the results can be used in optimizing energy absorptivity through the use of appropriately designed architectures and hybrid systems.

Many factors influence SMC cure behavior including mold temperature, SMC temperature, formulation, and aging. Although most of these factors are controlled to some extent, small uncontrollable variations will always cause some degree of fluctuation in cure behavior. The recent development of in- mold cure sensors allows the analysis and control of these variations from part to part and from batch to batch. In this study, SMC molding was monitored for thousands of parts and analyzed using Statistical Process Control (SPC) methods. The standard deviation in part to part cure times was found to be on the order of 1 to 5 seconds depending on factory conditions. A strong correlation of cure time with mold surface temperature was found, however, other uncontrolled parameters were found to have an additional significant influence. The cure sensor and monitoring system was connected to the press controller thus implementing closed loop control.

Toyota Motor Corporation has mass-produced turbochager with sillicon nitride ceramic rotors. A moment of inertia was reduced by 60% using ceramic rotor which improved turbochager response. The ceramic rotor was joined to metal shaft by new method which compensated problems in both shrink fitting and active brazing methods. They are generals for mechanical and chemical techniques, respectively. There still exist the following disadvantages. It is quite severe to controll the clearance of shrink fitting to obtain the reliability of the joint. The shaft may be loosened at high temperature with a small shrink-fit interference. The large shrink-fit interference could result in a failure of ceramic shaft due to large stress. Those may require a machinig accuracy with micron meter order of surface roughness which, leads to high cost.

The stringent durability requirements approaching 100,000 vehicle miles for automotive substrates and 290,000 vehicle miles for large frontal area diesel substrates for 1994+ model year vehicles call for advanced packaging designs with thick ceramic mats and high mount densities. The latter result in high mounting pressure on the substrate and enhance its mechanical integrity against engine vibrations, road shocks and back pressure forces. A novel measurement technique which applies a uniform biaxial compressive load on the lateral surface of ceramic substrates, thereby simulating canning loads, is described. The biaxial compressive strength data obtained in this manner help determine the maximum mounting pressure and mat density for a durable packaging design. The biaxial compressive strength data for both round and non round substrates with small and large frontal area are presented.