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Three-way catalysts which remove different kinds of pollutants, such as CO, THC(total hydro-carbon) and NOx, simultaneously from the automotive exhaust gas employ Rhodium(Rh) in combination with Platinum(Pt) and Palladium(Pd). Rh is the most effective for reducing NOx to N2, but Rh is the most expensive of these precious metals. The ratio of Rh to Pt applied for automobiles frequently exceeds the natural production. The gap between supply and demand of Rh sometimes causes the big price fluctuation. Accordingly, many attempts to reduce the amount of Rh loaded or to develop non-Rh three-way catalysts have been made. Although Pd catalysts are considered to be promising candidates for non-Rh automotive three-way catalysts, some performance are still inferior to Pt-Rh catalysts. We have found that an excellent three-way catalytic activity appears by compounding new Perovskite-structured oxides with Pd and auxiliary oxides.

Among the forces acting on an occupant during the deployment of an airbag, the impact force due to gas jets coming out of the inflator may be important. Consequently, the semi-analytical theory of high-velocity gas jets including velocity spreading due to turbulent diffusion has been incorporated into the explicit finite element computer program PAM-SAFE for occupant safety. The jet model, described in this paper, takes into account the geometry and thermodynamics of the inflator, the transfer of jet momentum to the moving airbag and the distribution of momentum due to diffusion. Since the intersection of every jet with the airbag is computed each timestep, the algorithm is consistent with numerical airbag unfolding. Experimental validation of the jet model has been performed at Automotive Systems Laboratory Inc. by firing actual inflators on rigid flat plates at several distances.

This paper directs attention to a specific region of the air-bag deployment process. Both experimental and analytical results are presented. Experimental procedures and their results are presented along with a two dimensional unsteady isentropic CFD model and a empirical gas-jet model.

A new type of sensor capable of sensing the direction and velocity of motion of smooth surfaced metallic targets is described. The sensor consists of a small permanent magnet and a magnetic field sensor displaced from each other along the line of motion, each at a small fixed distance from the target surface. Operation is based on the motion dependent location, strength and polarity of magnetic field sources created within proximate target regions via their passage through the field of the magnet. The fields arising from these target regions are detected by the magnetic field sensors, typically Hall effect or magnetoresistive devices. With ferromagnetic targets, a non-volatile memory of the direction of last occurring motion is also provided. Utility of these sensing capabilities is illustrated by descriptions of applications for automatic turn signal canceling and antitheft devices, back-up alarm activation and for engine misfire detection via crankshaft speed variation.

For the measurement and control of angular position or rotational speed in automobiles, the environmental conditions have led manufacturers to mainly specify magnetic sensors. They are able to withstand high shock and vibration, the presence of oil, dust or salt spray, and can operate over a temperature range as wide as -40°C to +150°C. Magnetic sensors generally meet these goals better than optical devices. Increasingly, though, modern engine control requirements call for much higher resolutions, and this paper describes how the environmental conditions are accomplished in a high resolution magnetic device. Three different configurations that are applicable to automobiles are described: a stand-alone encoder mounting to a stub shaft, a stand-alone encoder mounting over a through shaft, and a modular encoder comprising independent encoder wheel and sensor components.

We would like to discuss a set of unique concepts in active-occupant-restraint (airbag) systems which are unlike presently used airbags. Like present airbags, the concepts we will discuss are only designed to be deployed when vehicle sensors determine that the magnitude of a crash will imminently surpass a preset threshold. In other words, we are dealing with a state of a crash from which an occupant without an airbag is not likely to “walk-away”, a state of a crash after which a vehicle is not likely to be worth-while repairing, the type of a crash that we will refer to in this paper as a “catastrophic” crash, a “grievous” crash, to borrow from the dictionary. These concepts not only protect the front torso of an occupant, but also the back of the neck, and the sides of an individual body by actually enveloping her or him with a protective cushion.

An airbag upon collision of automobiles must finish expanding at the time when the driver's body arrives at the surface of the expanded airbag from the normal position and it must receive the body softly. Either early or late expansion reduce the effect. Determination of the optimal timing for trigger the airbag is quite important. But it is a difficult job, due to the time delay in the bag filling with the gas after collision. This paper focuses on the issue of the airbag technology to how to find the optimal trigger timing and presents a new and straightforward algorithm to determine the timing by introducing the concept of the prediction. The algorithm first predicts how the driver's body will move in the future time for a time equivalent to the delay time and triggers the airbag by the predicted information so that it can compensate the delay by the airbag operation.

In repeated surveys, technicians and shop owners tell us their greatest needs are training and information. Clearly, the Clean Air Act is planned to help to satisfy these needs. One major problem is access, how do I find the information I need? Where can I get the training I need? Vehicle maintenance depends on the total industry service capabilities, to include OEM dealers, aftermarket independents, fleet service, mass marketers. The latter accomplish the greater proportion of service, normally four times the amount of service as new-car dealers. In the interest of long-term customer satisfaction and its effect on new vehicle sales, OE manufacturers and their dealers have a compelling interest in proper vehicle maintenance by the total industry.

Increasing demand to equip vehicles with airbags in relatively short time is straining restraint engineering resources of OEMs and suppliers. To meet this demand, the time to develop the airbag systems should be minimized, without any compromise to their occupant protection performance. Among the various components that go into an airbag, the design and development of the gas generator is the most time consuming. Usage of one gas generator in a group of cars will cut down on the module development time. Therefore, the possibility of differentiating the inflators based on the severity of crash pulse was investigated. The usefulness of computer simulation software to obtain a good starting system was also evaluated. This paper outlines the procedure followed in identifying the optimum passenger side inflatable restraint system for a group of vehicles. The simulation and sled test matrices used towards this end are discussed and the results compared.

As an alternative refrigerant for CFC-12, HFC-134a is the best choice in automotive air conditioning system. Refrigeration cycle characteristics using HFC-134a have been previously reported, but most of those papers were confined to the differences of basic system performance between CFC-12 and HFC-134a. So this paper emphasized the analysis on functional components. As a result, we have introduced the differences of refrigeration cycle characteristics which had not been acquainted well by now.

Concerns on environmental protection are being intensified throughout the world in recent years. Of those concerns, depletion of the ozone layer in the atomosphere caused by CFC emission into the atomosphere is the target of serious concern as shown in Fig. 1. At present, the use of CFC production is restricted by regulations at the global level, and CFC will be phased out by the end of 1995. In this regard, the authors have developed a new vehicle air conditioner to adapt to a new refrigerant HFC-134a, which is gentle to the ozone layer, and to replace CFC-12. The new refrigerant system was introduced to the market in October, 1991, and the replacement will be almost completed by the end of 1993 for the Lexus and Toyota production vehicles. This paper describes the development of the new compressor lubricant, seal rubber, hose and desiccant by taking into consideration the materials concerned and the number of technological issues involved in the new refrigerant, HFC-134a.

Two aspects of a motorcycle injury crash are studied in this paper. 1) What were the rider's actions which led to unsafe handling of the motorcycle? 2) What were the injury-producing mechanisms present during the crash? This inquiry illustrates methods and procedures which are useful for motorcycle safety design as well as reliability analysis. The ADAMS™ mechanical system simulation program is used to generate computer models of a motorcycle and rider under rider control to simulate a mild lane change maneuver. Manual control and vehicle response characteristics are evaluated for a cases involving a system disturbance such as an encounter with a road pothole during the turning phase in the lane change.

The finite element method (FEM) is generally utilized to investigate the chassis strength of a motorcycle. However, it is difficult to determine the load conditions for FEM analysis of a drop test. Therefore, a method of drop test strength prediction at the basic design stage has been developed by combining stress analysis with vehicle dynamics analysis. A mathematical model and computer simulation system have been developed to predict the load conditions obtained by accelerations at several chassis locations. The model is constructed using flexible bodies (e.g., front fork and rear arm) as well as rigid bodies. The flexible front fork model was made by combining beam theory with substructural methods. Also, the model includes a front fork friction model which describes Coulomb's friction in slide bushings. If dynamic analysis is replaced by an equivalent static analysis, the force can be predicted from the acceleration data and the mass distribution.

This report describes the development of an air fuel ratio sensor with a linear voltage output, and its signal processing module that is able to calibrate the sensor output function on the measuring point of the 20.9% oxygen concentration in atmospheric air and the zero diffusion current at stoichiometry as the reference. This sensing system is effective when applied to air fuel ratio PID feed back engine control and it is able to realize the reduction of initial variability of sensors, interchangeability of sensors, and long term output change of the sensor.

The air conditioning systems of a fleet of sixteen (16) globally distributed vehicles have been retrofit to HFC-134a and ester-based lubricants. The variables of a generic flush-type retrofit procedure have been systematically changed. The effects of compressor condition (new or pre-conditioned), desiccant type (re-used XH-5 or new XH-7), evacuation times, and charge of mineral oil and HFC-134a were examined, in an attempt to better understand the significance of these specific variables on performance and durability of mobile air conditioning systems under retrofit conditions. Initial performance, measured qualitatively by cooling performance and quantitatively by compressor clutch cycling, is judged to be acceptable. Additional information will be provided, as available, on long-term durability of these systems.

This paper describes an advanced bypass flow passage configuration for a thermal air flow sensor which increases the dynamic flow-rate range, and describes its basic fluid mechanic relations in terms of Bernoulli' s principle. This configuration consists of a main flow path and two bypasses located inside the main flow path. Thermal and temperature compensation probes are installed only in the primary bypass. The secondary bypass connects with the primary bypass downstream of the probes. The flow velocity, and consequently the pressure, in the primary bypass is affected by this conflux. The conflux loss coefficient increases as the flow rate in the secondary bypass increases. As a result, the flow velocity in the primary bypass decreases as the total air flow rate increases. In tests, the dynamic range is shown to be increased by about 30% for flow velocities in the primary bypass of between 0.5 m/s and 50 m/s.

Emissions tests were performed to study the operating characteristics of a wide range air/fuel ratio (AFR) sensor in closed loop control. The AFR sensor used here has an output voltage with respect to AFR that is linear and can be characterized by a fourth order polynomial function. For this study the output signal of the AFR sensor was fed into a General Control Unit (GCU). The GCU converted this analog input signal into a square wave similar to a lambda sensor. The output from the GCU was fed into the Engine Control Unit (ECU) of the 3.8L, V6 test engine to control the engine A/F ratio. Emissions tests were conducted in closed loop mode under steady state and transient condition. Emissions of HC, CO and NOx using the AFR sensor will be shown. Results of these tests showed that the AFR sensor allowed for precise control of the AFR at the stoichiometric point (λ = 1.0).

Two additive blends proposed for improving the flame luminosity in neat methanol fuel were investigated to determine the effect of these additives on the exhaust emissions in a dual-fueled Volkswagen Jetta. The two blends contained 4 percent toluene plus 2 percent indan in methanol and 5 percent cyclopentene plus 5 percent indan in methanol. Each blend was tested for regulated and unregulated emissions as well as a speciation of the exhaust hydrocarbons resulting from use of each fuel. The vehicle exhaust emissions from these two fuel blends were compared to the Coordinating Research Council Auto-Oil national average gasoline (RF-A), M100, and M85 blended from RF-A. Carter Maximum Incremental Reactivity Factors were applied to the speciated hydrocarbon emission results to determine the potential ozone formation for each fuel. Toxic emissions as defined in the 1990 Clean Air Act were also compared for each fuel.

An oxidizing catalytic converter was evaluated in the exhaust train of a 3.73 kW (5 hp) natural gas engine. The engine was developed for use in a gas engine-driven heat pump and is designed for operation at lean air/fuel ratios. The converter tested had a metallic substrate with a cell density of 31 cells/cm2. Converter tests measured emission performance as a function of the key engine variables: speed, load, spark advance and air/fuel ratio. As expected, CO conversion averaged well above 90 percent. Hydrocarbon conversion varied between 68.6 and 89.8 percent over a range of eight speed and load combinations selected to cover the normal operating range of the engine. Conversion of individual hydrocarbon species was examined also. Although the converter tests were not designed to isolate the key converter variables, a simple mathematical model allowed us to explore the effect of these variables on conversion.

Conventionally, turbulent burning velocity models are compared by showing the model-predicted ST/SL0 ratios in an ST/SL0 - u′/SL0 plane, where ST and SL0 are the turbulent and laminar burning velocities, respectively, with u′ being the turbulence intensity. Such a method applies to only those models which take u′ or u′/SL0 as the only variable of ST or of ST/SL0. In order to analyze and compare most recent models in which turbulence and flame spatial scales (or length scales) are also taken into account because of their importance in combustion, this paper showed the model-predicted ST/SL0 ratios as contours in three planes (Re-Da, ηκ/η0 - u′/SL0 and L/η0 - u′/SL0, where Re, Da, L, ηκ and η0 are the Reynolds number, Damköhler number, turbulence integral scale, Kolmogorov scale and laminar flame preheat zone thickness, respectively); these planes are usually used in discussing the flame structure.