Search Results

An accurate estimation of cycle-by-cycle in-cylinder mass and the composition of the cylinder charge is required for spark-ignition engine transient control strategies to obtain required torque, Air-Fuel-Ratio (AFR) and meet engine pollution regulations. Mass Air Flow (MAF) and Manifold Absolute Pressure (MAP) sensors have been utilized in different control strategies to achieve these targets; however, these sensors have response delay in transients. As an alternative to air flow metering, in-cylinder pressure sensors can be utilized to directly measure cylinder pressure, based on which, the amount of air charge can be estimated without the requirement to model the dynamics of the manifold.

One important design goal for spark-ignited engines is to minimize cyclic variability. A small amount of cyclic variability (slow burns) can produce undesirable engine vibrations. A larger amount of cyclic variability (incomplete burns) leads to increased hydrocarbon consumption/emissions. Recent studies have reported deterministic patterns in cyclic variability under extremely lean (misfiring) operating conditions. The present work is directed toward more realistic non-misfiring conditions. Production engine test results suggest that deterministic patterns in cyclic variability are the consequence of incomplete combustion, hence control algorithms based on the occurrence of these patterns are not expected to be of significant practical value.

In this work, a discrete,time-based, delay-compensated, adaptive PID control algorithm for air fuel ratio control in an SI engine is presented. The controller operates using feedback from a wide-ranging Universal Exhaust Gas Oxygen (UEGO) sensor situated in the exhaust manifold. Time delay compensation is used to address the difficulties traditionally associated with the relatively long and time-varying time delay in the gas transport process and UEGO sensor response. The delay compensation is performed by computing a correction to the current control move based on the current delay and the corresponding values of the past control moves. The current delay is determined from the measured engine speed and load using a two dimensional map. In order to achieve good servo operation during target changes without compromising regulator performance a two degree of freedom controller design has been developed by adding a pre-filter to the air fuel ratio target.

Ford Motor Company introduced the inflatable seatbelt system in 2011 and the system is now available in the second row of several Ford and Lincoln models. An important consideration is the interaction of the inflatable seatbelt system with child restraint systems (CRS). A comprehensive series of frontal impact sled tests, using a standardized test method, was conducted to compare the performance of rear-facing-only CRS installed using an inflatable seatbelt to the same CRS installed using a standard seatbelt. CRS models from several manufacturers in the North American market were tested both with and without their bases. CRABI 12 month old or Hybrid III 3 year old anthropomorphic test devices (ATD) were restrained in the CRS. The assessment included the ability to achieve a satisfactory installation with the inflatable seatbelt, comparisons of ATD and CRS kinematics, CRS system integrity, and comparisons of ATD responses.

With the increasing emphasis on and importance of aerodynamics on vehicle fuel economy and handling, conservative approaches to sizing front-end cooling openings based on projected radiator area need to be replaced by a performance-based method. The method would not only allow more flexibility in front-end styling, but would enable the design of the grille, cooling hardware and vehicle heat rejection requirements to be based on the cooling performance of the total vehicle. The reductions in cooling drag and front lift from smaller, but more functional, grille openings would improve vehicle fuel economy and handling. A performance-based front-end design approach is described in the paper along with some selected experimental results. The method is based on an experimental technique for simultaneously measuring the total radiator airflow and vehicle aerodynamic performance in an aerodynamic wind tunnel.

In a continuing effort to include real-world emissions in regulatory testing, the USEPA has included air conditioning operation as part of the Supplemental Federal Test Procedure (SFTP). Known as the SC03, these tests require automobile manufacturers to construct and maintain expensive environmental chambers. However, the regulations make allowances for a simulation test, if one can be shown to demonstrate correlation with the SFTP results. We present the results from an experiment on a 1998 Ford sedan, which simulates the heat load of a full environmental chamber. Moreover, the test procedure is simpler and more cost effective. The process essentially involves heating the condenser of the air conditioning system by using the heat of the engine, rather than heating the entire vehicle. The results indicate that if the head pressure is used as a feedback signal to the radiator fan, the load generated by a full environmental chamber can be duplicated.

The number of computational fluid dynamics (CFD) simulations performed during the vehicle aerodynamic development process continues to expand at a rapid rate. One key contributor to this trend is the number of analytically based designed experiments performed to support vehicle aerodynamic shape development. A second contributor is the number of aerodynamic optimization studies performed for vehicle exterior components such as mirrors, underbody shields, spoilers, etc. A third contributor is the increasing number of “what if” exploratory studies performed early in the design process when the design is relatively fluid. Licensing costs for commercial CFD solutions can become a significant constraint as the number of simulations expands.

The equipment for collecting dilute exhaust samples involves the use of bag materials (i.e., Tedlar®) that emit hydrocarbons that contaminate samples. This study identifies a list of materials and treatments to produce bags that reduce contamination. Based on the average emission rates, baked Tedlar®, Capran® treated with alumina deposition, supercritical CO2 extracted Kynar® and supercritical CO2 extracted Teflon NXT are capable of achieving the target hydrocarbon emission rate of less than 15 ppbC per 30 minutes. CO2 permeation tests were also performed. Tedlar, Capran, Kynar and Teflon NXT showed comparable average permeation rates. Based on the criteria of HC emission performance, changes in measured CO2 concentration, ease of sealing, and ease of surface treatment, none of the four materials could be distinguished from one another.

This paper provides an overview of the effects of blending ethanol with gasoline for use in spark ignition engines. The overview is written from the perspective of considering a future ethanol-gasoline blend for use in vehicles that have been designed to accommodate such a fuel. Therefore discussion of the effects of ethanol-gasoline blends on older legacy vehicles is not included. As background, highlights of future emissions regulations are discussed. The effects on fuel properties of blending ethanol and gasoline are described. The substantial increase in knock resistance and full load performance associated with the addition of ethanol to gasoline is illustrated with example data. Aspects of fuel efficiency enabled by increased ethanol content are reviewed, including downsizing and downspeeding opportunities, increased compression ratio, fundamental effects associated with ethanol combustion, and reduced enrichment requirement at high speed/high load conditions.

Low Temperature Combustion (LTC) engines are promising to improve powertrain fuel economy and reduce NOx and soot emissions by improving the in-cylinder combustion process. However, the narrow operating range of LTC engines limits the use of these engines in conventional powertrains. The engine’s limited operating range can be improved by taking advantage of electrification in the powertrain. In this study, a multi-mode LTC-SI engine is integrated with a parallel hybrid electric configuration, where the engine operation modes include Homogeneous Charge Compression Ignition (HCCI), Reactivity Controlled Compression Ignition (RCCI), and conventional Spark Ignition (SI). The powertrain controller is designed to enable switching among different modes, with minimum fuel penalty for transient engine operations.

This paper examines the neck tension force (Fz) of the BioRid II dummy in the IIHS (Insurance Institute of Highway Safety) rear impact mode. The kinematics of the event is carefully reviewed, followed by a detailed theoretical analysis, paying particular attention to the upper neck tension force. The study reveals that the neck tension should be approximately 450N due to the head inertia force alone. However, some of the tests conducted by IIHS had neck tension forces as high as 1400N. The theory of head hooking and torso downward pulling is postulated in the paper, and various publicly available IIHS rear impact tests are examined against the theory. It is found in the analysis that in many of those tests with high neck tension forces, the locus of the head restraint reaction force travels on the dummy's skull cap, and eventually moves down underneath the skull cap, which causes “hooking” of the head on the stacked-up head restraint foam.

Phosphorous poisoning on customer-aged catalysts was investigated by material analysis and performance testing. Most of the phosphorus was associated with the oxide components in the washcoat. These contaminants were roughly classified as aluminum phosphate, cerium phosphate, zinc-calcium phosphate. Deactivation of the catalyst with aluminum phosphate was strong and followed a linear correlation from oxalic acid testing. Phosphorus scavenging additives were researched to inhibit increase of aluminum phosphate. According to thermodynamic calculations, lower free energy of compounds of additive and phosphate is expected to prevent formation of aluminum phosphate.

A two-dimensional analytical model is developed by solving the differential equations which describe the motion of a vehicle in laboratory-based rollover events. The model is based on a rigid-body kinematics assumption for the entire vehicle. Three cases are studied: the first case deals with determination of the Critical Sliding Velocity of a vehicle rolls over from a tilt table, the second case considers rollover of a vehicle which sits on a platform traveling at a velocity V which is suddenly stops, and the third one repeats the second problem except that the platform is brought to stop according to a given deceleration profile, thus simulating the SAE J2114 rollover test procedure. For the SAE J2114 rollover test procedure simulation, the analytical results are compared with those obtained from MADYMO-based rollover model.

A significant route for water ingress into passenger cars is through the Heating, Ventilating, and Air-Conditioning (HVAC) system. The penetration of rainwater through the HVAC unit and the subsequent rise in moisture levels within the passenger compartment directly affect the provision of thermal comfort to the cabin occupants. It is speculated that up to 80% of water ingress into the cowl or engine bay is from water film movement over the bonnet of the car, and only the remaining 20% is from direct rain impact from above. Using a full-scale Climatic Wind Tunnel (CWT) facility, which incorporates accurate rain distribution modeling, it has been possible to study the movement of rainwater film over the exterior surface of the vehicle to ascertain the flow distribution of the film moving into the engine bay, into the cowl, advancing up and over the windscreen and shed to the sides and front of the vehicle.

A normalized analytical vehicle fuel consumption model is developed based on an input/output description of engine fuel consumption and transmission losses. Engine properties and fuel consumption are expressed in mean effective pressure (mep) units, while vehicle road load, acceleration and grade are expressed in acceleration units. The engine model concentrates on the low rpm operation. The fuel mep is approximately independent of speed and is a linear function of load, as long as the engine is not knock limited. A linear, two-constant engine model then covers the speed/load range of interest. The model constants are a function of well-known engine properties. Examples are discussed for naturally aspirated and turbocharged SI engines and for Diesel engines. A similar model is developed for the transmission where the offset reflects the spin and pump losses, and the slope is the gear efficiency.

This paper presents a methodology that makes use of computer based analytical simulation methods combined with statistical tools to predict timing belt life. This allows timing belt life to be estimated with no requirement for running test engines and associated test equipment, which is both very time and expense exhaustive. A case study on a belt driven primary drive for a V6 Diesel engine was used to illustrate the methodology. A computer based dynamic model for the belt drive system was developed and validated, and a belt life prediction model was developed, which uses tooth load predictions from the analytical model. Statistical modeling of predicted damage accumulated to failure was used to estimate the model parameters given a limited set of belt life results from a motored rig test. The practical use of the model is illustrated by predicting belt life under customer usage.

In the early days of the automotive industry, durability and reliability were hit or miss affairs, with end-users often being the first to know about any durability problems - and in many cases forming an essential part of the development process. More recently, automotive companies have developed proving ground and laboratory test procedures that aim to simulate typical or severe customer usage. These test procedures have been used to develop the products through a series of prototypes and to prove the durability of the product prior to release in the marketplace. Now, commercial pressures and legal requirements have led to increasing reliance on CAE methods, with fatigue life prediction having a central role in the durability engineering process.

The chain link and sprocket tooth impact during a meshing has been identified as the most significant noise source in a chain drive system. This paper first presents the theoretical derivation of the chain drive natural frequencies and mode shapes using the equations of motion from a stationary undamped chain drive system. The theoretical derivation shows the existence of three types of chain resonances, namely the transverse strand resonance, the longitudinal chain sprocket coupled resonance and the longitudinal chain stress wave type resonance. The chain-sprocket meshing noise is amplified when the chain sprocket meshing frequency corresponds to any one of the above mentioned chain drive system resonances. These theoretical results are then validated by a chain drive system CAE model using ABAQUS to identify the chain drive system resonances.

In recent years, the slip lock-up mechanism has been adopted widely, because of its fuel efficiency and its ability to improve NVH. This necessitates that the automatic transmission fluid (ATF) used in automatic transmissions with slip lock-up clutches requires anti-shudder performance characteristics. The test methods used to evaluate the anti-shudder performance of an ATF can be classified roughly into two types. One is specified to measure whether a μ-V slope of the ATF is positive or negative, the other is the evaluation of the shudder occurrence in the practical vehicle. The former are μ-V property tests from MERCON® V, ATF+4®, and JASO M349-98, the latter is the vehicle test from DEXRON®-III. Additionally, in the evaluation of the μ-V property, there are two tests using the modified SAE No.2 friction machine and the modified low velocity friction apparatus (LVFA).

The overall purpose of this research is to determine the antiwear capability of low phosphorus engine oils containing 0.05 wt% phosphorus. The antiwear performance of 0.05 wt% phosphorus engine oils was evaluated using a laboratory valvetrain bench test rig coupled with an on-line wear measurement technique and a high frequency reciprocating rig (HFRR). Low phosphorus engine oils were compared with GF-3 engine oils containing 0.1 wt% phosphorus. In addition to fresh oils, long drain used oils from fleet vehicles were also analyzed and investigated. This information is important to develop engine oil formulations to meet the latest government emission and fuel economy requirements. The results indicate that by appropriately selecting and balancing supplemental antiwear and/or antioxidation additives the wear loss due to the reduction of zinc dialkyldithiophosphate (ZDDP) may be compensated or even reduced.