AIR-INTAKE MANIFOLD

Premature ignition can be reduced or eliminated by redesigning the fuel delivery system, which can be categorized into three types central-, port-, and direct injection. Central and port fuel injections form the fuel-air mixture during the intake stroke. In the case of central injection (or a carburetor), the injection is at the inlet of the air intake manifold. In the case of port injection, fuel is injected at the inlet port. Direct injection is technologically sophisticated and involves forming the fuel-air mixture inside the combustion cylinder after the air intake valve has closed [27-36]. 

Many automakers use reinforced nylon for air intake manifolds because of direct advantages, for example ... 

Fig. 2 Primary energy consumption within the life cycle of two air intake manifolds made of different materials in a gasoline driven car...

The following detailed conclusions were derived for the air-intake manifold ... 

Eyerer P, Dekorsy Th, Schuckert M, Pfleiderer I Developing a comprehensive balance of an automotive air intake manifold. German Plastics 83 (1993) 3, S16-19 Wolf MA, Eyerer P (2004) The life cycle accident assessment (LCAA) - emissions and casualties from non-normal operation and use. Presentation at sixth international conference on ecobalance, Tsukuba, Japan, October 25-27 2004... 

The sensor is installed in the air intake manifold of the car, measuring the aspirated air mass. The measuring principle requires the membrane to be exposed to the airflow and thereby also to dust and other particles, which are either not removed by the air filter or are inherent in the intake pipe. The impact of such particles on the membrane imposes a shock-type mechanical load, which can cause field failures as well as O-km failures due to membrane fracture. The task was to identify the relevant geometry and material parameters limiting the lifetime of the sensor element and to deduce a model for their effects on membrane stability [11]. 

A full-scale model of the air intake manifold, where the complete sensor (with signal processing ICs, housing, cable fittings, etc.) can be tested under real-life conditions, was available. However, failure rates of components in automotive applications under normal conditions are on the order of a few ppm, which corre-... 

Fig. 5.9.15 Weibull representation of lifetimes of full-scale models of air intake manifold subjected to dust-particle stream...

Central and port fuel delivery systems injection form the fuel-air mixture during the intake stroke. In the case of central injection or a carburetor, the injection is at the inlet of the air intake manifold. In the case of port injection, it is injected at the inlet port. 

Particularly sophisticated tooling is used for major application for RTFs such as automobile air intake manifolds. These large (1.5-3 kg) moldings, in glass fiber/reinforced nylon, are IM on fusible metal cores, which are subsequently melted out, or are molded as two mirror images, which are then ultrasonically welded together. 

Furthermore, LCAs are used in evaluations of different product alternatives in collaboration with industrial clients. For example, a life cycle analysis has been performed for Ford, comparing an air-intake manifold in aluminium (manufactured by a particular process at a specified processor) to one made from Zytel by a specified process and processor [28]. Some of the results are displayed in Figures 7.16 - 7.19 (First published in German Plastics 83, 3 (1993)). 

Figure 7.16 Weight of and energy consumption during production and use of air-intake manifolds made from ZYTEL and aluminium.

Figure 7.17 Air emissions during production for an air-intake manifold made from ZYTEL or aluminium.

Figure 7.18 Global warming potential for ZYTEL and aluminium air-intake manifolds during production and use.

M. Schuckert, Th. Dekorsy, I. Pfleiderer, and P. Eyerer, Developing a Comprehensive Balance cfan Automobile Air Intake Manifold, Kunststoffe - German Plastics, 83,3, pp. 16-19 (1993). 

The plastic (usually nylon) air intake manifold weighs half as much as one made from pressure-cast aluminium, and improves engine performance with its smoother inner surfaces, which minimize airflow resistance. The manifold is injection-moulded (see Chapter 7) and so secondary machining costs are eliminated. Additionally, because nylon is less thermally conductive than aluminium, the engine runs slightly hotter, which leads to a reduction in emissions the plastic manifold engines also have a shorter warm-up time. 

A limited amount of nylon recycling from appliances and antomotive parts is taking place as well. For example, DuPont is working on recycling radiator tanks and air intake manifolds into nylon materials for new tanks and manifolds ... 

DuPont, Toyota, DuPont Engineering Polymers Show Value of Composite Recycle Technology in Automotive Air Intake Manifolds, news release, March 8, 2004. 

Nylon 6,6. Nylon 6,6 appears in automotive applications mostly in impact-modified, blended, and filled (mostly glass reinforced, with or with out impact modifiers) form. Impact modification of nylon 6,6 is of significant commercial importance, especially for automotive uses. Typical applications include fasteners for interior and exterior components, a host of connectors, holding fixtures, and radiator end caps, and a fairly common application is for air intake manifolds (Fig. 9.4). These applications rely on the ductility and toughness of impact-modified nylon 6,6 as a mechanism to connect assemblies or join components. 

Vibration welding is nsed extensively by the automotive industry in the manufacture of components snch as car bumpers, air intake manifolds, fuel pumps, instrument panels, parcel shelves, inner door panels and for the hermetic sealing of air ducting to the internal surface of the dashboard. Other applications include spectacle frames, typewriter covers, filter housings, motor saw housings and heating valves. 

The European Commission has proposed a technical directive forcing manufacturers to record the polymers used in the construction of vehicles, so as to facilitate recycling. DuPont Engineering Polymers says that its polyamide 6 derived from old automotive parts can be recovered and reused, still being within specification for use in automotive air intake manifolds. Toyota has verified that DuPont s process justifies the claims made. 

Leone and Oliver [42] have discussed the applications of fluoroelastomers, nitrile rubber (NBR) and hydrogenated NBR in seals for automotive air-intake manifolds. They review the properties required for such seals including mechanical and low temperature properties, heat and fuel resistance, and design requirements for the seals used in conjunction with the engineering plastics components in this application. 

Figure 29.6 On-engine TDLAS monitoring of CO2 transient dynamics within the air intake manifold of production internal combustion engines. Left principle of the fibre-coupled sensor set-up right sensor incorporated into an actual manifold inset CO2 concentration measurement, with 1 s temporal resolution. Adapted from Sonnenfroh etal, 30th Int. Symp. on Combustion, 2004, with permission of Physical Sciences Inc...

LCA for the end-of-Ufe was used for seven plastic components that are commonly used in automotive applications. The parts included the bumper cover made from polypropylene (PP), windshield washer fluid container made from polyethylene (PE), air-intake manifold made from 30% glass-filled nylon, air duct made from 20% talk-filled PP, seat cushion made from polyurethane foam, head lamp lenses made from polycarbonate, and mirror housing made from acrylonitrile butadiene styrene (Jenseit et al. 2003). 

Mechanical recycling of the plastics obtained the lowest cost and lowest environmental burden than energy recovery and landfill options. The LCA work determined that in the cases with minimum disassembly time of plastic parts and 1 1 substitution with virgin plastics (PP bumper, HDPE fluid container, and glass-filled nylon air-intake manifold) mechanical recycUng of the plastics obtained the lowest cost and lowest environmental burden than energy recovery and landfill options. 

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