Search Results

Onboard diagnostic regulations require performance monitoring of diesel particulate filters used in vehicle aftertreatment systems. Delphi has developed a particulate matter (PM) sensor to perform this function. The objective of this sensor is to monitor the soot (PM) concentration in the exhaust downstream of the diesel particulate filter which provides a means to calculate filter efficiency. The particulate matter sensor monitors the deposition of soot on its internal sensing element by measuring the resistance of the deposit. Correlations are established between the soot resistance and soot mass deposited on the sensing element. Currently, the sensor provides the time interval between sensor regeneration cycles, which, with the knowledge of the exhaust gas flow parameters, is correlated to the average soot concentration.

Current generation automobiles are controlled by electronic modules for performing various functions. These electronic modules have numerous semiconductor devices mounted on printed circuit boards. Solders are generally used as thermal interface material between surface mount devices and printed circuit boards (PCB) for efficient heat transfer. In the manufacturing stage, voids are formed in solders during reflow process due to outgassing phenomenon. The presence of these voids in solder for power packages with exposed pads impedes heat flow and can increase the device temperature. Therefore it is imperative to understand the effect of solder voids on thermal characteristics of semiconductor devices. But the solder void pattern will vary drastically during mass manufacturing. Replicating the exact solder void pattern and doing detail simulation to predict the device temperature for each manufactured module is not practical.

In vehicular mobility context, it is extremely important for the environmental sustainability that the available energy will be used as efficiently as possible, both in the use of internal combustion engines (ICE) as powertrain, as well in the application of Hybrid and Electric Vehicle Motors (HEV/EV). In this comparison, ICE has a lower efficiency when compared to electric motors, wasting much of the potential energy of the fuel in form of heat and noise. On the other hand, the electric vehicles face limitation in autonomy and recharge time, demanding for a more efficient use of energy stored in batteries. This study aims to present emerging technologies for reuse of energy within the automotive context, originally known as “Energy Harvesting” and “Renewable Energies”.

Spot, or distributed, cooling and heating is an energy efficient way of delivering comfort to an occupant in the car. This paper describes an approach to distributed cooling in the vehicle. A two passenger CFD model of an SUV cabin was developed to obtain the solar and convective thermal loads on the vehicle, characterize the interior thermal environment and accurately evaluate the fluid-thermal environment around the occupants. The present paper focuses on the design and CFD analysis of the energy efficient HVAC system with spot cooling. The CFD model was validated with wind tunnel data for its overall accuracy. A baseline system with conventional HVAC air was first analyzed at mid and high ambient conditions. The airflow and cooling delivered to the driver and the passenger was calculated. Subsequently, spot cooling was analyzed in conjunction with a much lower conventional HVAC airflow.

Delphi Automotive Systems and BMW are jointly developing Solid Oxide Fuel Cell (SOFC) technology for application in the transportation industry primarily as an on-board Auxiliary Power Unit (APU). In the first application of this joint program, the APU will be used to power an electric air conditioning system without the need for operating the vehicle engine. The SOFC based APU technology has the potential to provide a paradigm shift in the supply of electric power for passenger cars. Furthermore, by supplementing the conventional fuel with reformate in the internal combustion engine, extremely low emissions and high system efficiencies are possible. This is consistent with the increasing power demands in automobiles in the new era of more comfort and safety along with environmental friendliness. Delphi Automotive Systems and BMW were successful in demonstrating an Auxiliary Power Unit (APU) based on Solid Oxide Fuel Cell (SOFC) technology in February, 2001.

Performance of two types of NOx adsorber catalysts, one based on Ba and the other based on Ba with alkali metals, was compared fresh and after thermal aging. Incorporation of sodium(Na), potassium(K) and cesium(Cs) into NOx adsorber washcoat containing barium significantly increases the NOx conversions in the temperature range of 350-600°C over that of the alkali metal free NOx adsorber catalysts. NOx performance benefit and HC performance penalty were observed on both engine dynamometer and vehicle tests for the “Ba+alkali metals” NOx adsorber catalysts. “Ba+alkali metals” NOx adsorber catalysts also demonstrate superior sulfur resistance with better NOx performance after repeated sulfur poisonings and desulfations over the “Ba based” NOx adsorber catalysts.

A jury evaluation study has been conducted to determine the hearing threshold of IP gauge stepping motor noise using a transformed up-down procedure. The stepping motor noise was recorded in an anechoic chamber and was used as a signal in the study. To determine the masked threshold, this signal was adjusted to various gain levels and mixed with interior engine noise at selected rpm as masking noise. In this study, the Adaptive Procedure was used, and a software application was developed for this purpose. Twenty subjects, selected based on hearing test results, participated in this jury evaluation. The findings of this study indicated that Adaptive Procedure is an effective approach in determining hearing threshold for automotive applications. A design criterion for acoustical characteristics of the IP gauge DC motor noise has been developed based on the results of this study.

This paper presents a simplified thermal model for round catalytic converters in steady state operation. Using this model, the analytic solution for the temperature distribution in the monolithic substrate is obtained. This analytic solution in the substrate is, then, combined with those in the intumescent mat [1] and the metal shell to obtain the temperature profile in the radial direction of the converter except for three unknown temperatures at the three material interfaces, which can be solved using an Excel application program. This analytical temperature solution facilitates the studies of the effects of various design parameters such as the exhaust gas temperature, exhaust gas flow rate, substrate cell geometry, converter dimensions, and ambient temperature and flow, etc.

Proposed vehicle emissions regulations for the near future have prompted automotive manufactures and component suppliers to focus heavily on developing more efficient exhaust aftertreatment devices to lower emissions from spark and compression ignition engines. One of the primary pollutants from lean-burn engines, especially from diesels, are oxides of nitrogen (NOx). Current three-way catalytic converters will not have adequate performance to meet future emission reduction requirements. Therefore, there is a need for researchers and engineers to develop efficient exhaust aftertreatment devices that will reduce NOx emissions from lean-burn engines. These devices must have very high conversion of NOx gases, be unaffected by exhaust-gas impurity such as sulfur, and have minimal impact on vehicle operations and fuel economy. An effective technology for NOx control that is currently receiving a lot of attention is a non-thermal plasma system.

Brake squeal phenomenon often involves modal coupling between various component modes. In order to reduce or eliminate squeal, it is very important to understand the coupling mechanism so that the key component(s) can be modified accordingly. This paper demonstrates a quantitative method to define system mode shapes using the concept of modal participation factors. This method is implemented on a front disc brake system to identify the modal coupling mechanism associated with its high frequency squeal. Complex eigenvalue analysis is carried out and the squeal frequency is correlated. System mode shapes are then processed with an in-house program to calculate modal participation factors based on a complex MAC (Modal Assurance Criteria) algorithm. The coupling mechanism is identified and possible countermeasures are discussed.

With new legislation and federal regulation for vehicle emission levels, automotive and truck manufacturers have been prompted to focus on emission control technologies that limit the level of exhaust pollutants. One of the primary pollutants, especially from diesel engines, is oxides of nitrogen (NOx). One possible solution to this pollution challenge is to design a more efficient internal combustion engine, which would require better engine operating parameter controls. However, there are limitations associated with such tight engine management. This need has led researchers and engineers to focus on the development of exhaust aftertreatment devices that will reduce NOx emissions with current diesel engines. An optimum aftertreatment device must be unaffected by exhaust-gas impurity poisoning such as sulfur products, and must have minimal impact on vehicle operations and fuel economy.

It is well known that hydrocarbon reduction during a cold start is a major issue in achieving ultra low emissions standards. This paper describes one of the possible approaches for reducing the cold-start hydrocarbon emissions by using a fast “light-off” planar oxygen sensor. The goal of this study was to verify the operation characteristics of Delphi's fast “light-off” planar oxygen sensor's (INTELLEK OSP) operating characteristics and the closed-loop performance for achieving improved hydrocarbon control for stringent emission standards. Tests were conducted in open-loop and closed-loop mode under steady and transient conditions using a 1996 model year 2.4-liter DOHC in-line 4-cylinder engine with a close-coupled catalytic converter. Overall performance of the OSP showed relatively quick reaction time to reach the operating temperature.

Optimization of the mechanical aspects of a heated conical oxygen sensor for desired performances, such as low heater power, good poison resistance, fast light-off, and broad temperature range, etc. was achieved with computer modeling. CFD analysis was used to model the flow field in and around a sensor in an exhaust pipe to predict the convection coefficients, poisoning, and switching time. Heat transfer analysis coupled with electrical heating was applied to predict temperature and light-off time. Results of the optimization are illustrated, with good agreements between modeling and testing.

In the catalytic converter, the thermal conductivity of the insulation material (intumescent mat) placed between the ceramic catalyst and the metal shell is strongly dependent on the temperature, resulting in the solving of non-linear heat conduction equations. In this paper, the analytic solution for the steady heat flow in a cylinder with temperature dependent conductivity is given. Using this analytic solution for the mat and including convection and radiation at the converter skin, an analytical expression for calculating converter skin temperature is obtained. This expression can be easily incorporated in a Fortran code to calculate the temperatures.

Accurately predicting converter assembly deformation and mat pressure is essential in converter packaging design and manufacturing. In stuffing packaging, the annulus between the deformed shell and the catalyst is larger than that between the stuffing cone and the catalyst. As a result, the mat expands and undergoes unloading process. Tests show that the mat exhibits different loading and unloading characteristics. Using such a hysteresis mat pressure vs density curve in finite element analysis, the computed converter deformations closely agree with test data. Conversly, neglecting the mat hysteresis behavior may overestimate the deformation and pressure by a factor of three to four.

A front disc brake system is used as an example for an investigation of low frequency squeal. Many different modifications to this disc brake system have been proposed and this paper focuses on a solution that reduces the stiffness of the rotor. This is accomplished by a reduction in the Young's modulus of the rotor material. The complex eigenvalue method is used for a detailed analytical study in order to obtain a better understanding of this solution technique. Modal participation factors are calculated to examine the modal coupling mechanism. Parametric studies are also performed to find out the effects of friction coefficient and rotor stiffness. Results show that shifting rotor resonance frequencies may ecouple the modal interaction and eliminate dynamic instability, which is in agreement with experimental results.

The purpose of this report is to quantify the methodology for evaluating and isolating rattle noises in power rack & pinion steering systems. In today's ever changing market of vehicle body & suspension changes, it's very important that the correct process be used to identify the correct noise source. The results of this evaluation procedure will help sort out the difference between hydraulic generated noises and mechanical generated noises. The process used in sorting the hydraulic noise from the mechanical noise is through the use of a “standpipe”, which dampens the hydraulic reaction pulse in the hydraulic steering system. We refer to this hydraulic pulse as “hydraulic rattle”, and is often confused with mechanical rattle during vehicle evaluations. The concept of the standpipe is similar to that used in household plumbing, which reduces the effects of hydraulic hammering in the water pipes.

The problem being investigated involves a noise-quality issue on a power steering application, when a sudden change of steering wheel angle generates an unwanted steering system noise or “Squawk.” This phenomenon is mostly observed during parking maneuvers, especially at lock positions and when the hydraulic fluid reaches a critical temperature on the specific application. The objective of the work to solve this noise-quality issue was to first identify the cause and then eliminate the Squawk noise. There were several constraints: No change could be made in the properties or type of hydraulic fluid used due to specification requirements; Steering wheel valve torsion bar characteristic (torque vs. angle) needed to be maintained within specification for ride and handling purposes; and, In addition to the mentioned constraints, a high capability of noise elimination generated by the production tolerances and dispersion has been considered.