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Technical Paper

A Novel Approach to Real-Time Estimation of the Individual Cylinder Combustion Pressure for S.I. Engine Control

1999-03-01
1999-01-0209
Over the last decade, many methods have been proposed for estimating the in-cylinder combustion pressure or the torque from instantaneous crankshaft speed measurements. However, such approaches are typically computationally expensive. In this paper, an entirely different approach is presented to allow the real-time estimation of the in-cylinder pressures based on crankshaft speed measurements. The technical implementation of the method will be presented, as well as extensive results obtained for a V-6 S.I. engine while varying spark timing, engine speed, engine load and EGR. The method allows to estimate the in-cylinder pressure with an average estimation error of the order of 1 to 2% of the peak pressure. It is very general in its formulation, is statistically robust in the presence of noise, and computationally inexpensive.
Technical Paper

AFR Control on a Single Cylinder Engine Using the Ionization Current

1998-02-23
980203
Over the years numerous researchers have suggested that the ionization current signal carries within it combustion relevant information. The possibility of using this signal for diagnostics and control provides motivation for continued research in this area. To be able to use the ion current signal for feedback control a reliable estimate of some combustion related parameter is necessary and therein lies the difficulty. Given the nature of the ion current signal this is not a trivial task. Fei An et al. [1] employed PCA for feature extraction and then used these feature vectors to design a neural network based classifier for the estimation of air to fuel ratio (AFR). Although the classifier predicted AFR with sufficient reliability, a major draw back was that the ion current signals used for prediction were averaged signals thus precluding a cycle to cycle estimate of AFR.
Technical Paper

An Experimental Study on the Effect of Intake Primary Runner Blockages on Combustion and Emissions in SI Engines under Part-Load Conditions

2004-10-25
2004-01-2973
Charge motion is known to accelerate and stabilize combustion through its influence on turbulence intensity and flame propagation. The present work investigates the effect of charge motion generated by intake runner blockages on combustion characteristics and emissions under part-load conditions in SI engines. Firing experiments have been conducted on a DaimlerChrysler (DC) 2.4L 4-valve I4 engine, with spark range extending around the Maximum Brake Torque (MBT) timing. Three blockages with 20% open area are compared to the fully open baseline case under two operating conditions: 2.41 bar brake mean effective pressure (bmep) at 1600 rpm, and 0.78 bar bmep at 1200 rpm. The blocked areas are shaped to create different levels of swirl, tumble, and cross-tumble. Crank-angle resolved pressures have been acquired, including cylinders 1 and 4, intake runners 1 and 4 upstream and downstream of the blockage, and exhaust runners 1 and 4.
Technical Paper

An Investigation of Mixture Formation Processes During Start-Up of a Natural Gas Powered SI Engine

1998-05-04
981387
The mixture formation processes of methane and air in an optical access engine operating steadily at 200 RPM have been explored in order to study charge inhomogeneity in a natural gas powered spark ignition engine during transient engine cranking. Planar Laser Induced Fluorescence has been used to create fuel/air equivalence ratio maps as a function of injection timing for various image planes at intervals throughout the intake and compression strokes. The work has been done using a Honda VTEC-E engine head that features port injection, four valves per cylinder, a pentroof style combustion chamber for the generation of tumble motion, and one nearly deactivated intake valve to generate swirl motion at low engine speeds in order to enhance mixing.
Technical Paper

Approximating Engine Tailpipe Orifice Noise Sound Quality using a Surge Tank and In-Duct Measurements

2003-05-05
2003-01-1641
Because of the need to safely vent exhaust gases, most engine dynamometer facilities are not well suited to measuring engine exhaust orifice noise. Depending on the location of the dyno facility within the building, the exhaust system may need to be extended in order to properly vent the exhaust fumes. This additional ducting changes the acoustic modes of the exhaust system which will change the measured orifice noise. Duct additions downstream of the original orifice location also alter the termination impedance such that in-duct pressure measurements with and without the extended exhaust system can vary significantly. In order to minimize the effect of the building's exhaust system on the desired engine exhaust system measurements, the present approach terminates the engine exhaust into a large enclosed volume or surge tank before venting the gases into the building's ventilation system.
Technical Paper

Biomechanical Responses of PMHS Subjected to Abdominal Seatbelt Loading

2016-11-07
2016-22-0004
Past studies have found that a pressure based injury risk function was the best predictor of liver injuries due to blunt impacts. In an effort to expand upon these findings, this study investigated the biomechanical responses of the abdomen of post mortem human surrogates (PMHS) to high-speed seatbelt loading and developed external response targets in conjunction with proposing an abdominal injury criterion. A total of seven unembalmed PMHS, with an average mass and stature of 71 kg and 174 cm respectively were subjected to belt loading using a seatbelt pull mechanism, with the PMHS seated upright in a free-back configuration. A pneumatic piston pulled a seatbelt into the abdomen at the level of the umbilicus with a nominal peak penetration speed of 4.0 m/s. Pressure transducers were placed in the re-pressurized abdominal vasculature, including the inferior vena cava (IVC) and abdominal aorta, to measure internal pressure variation during the event.
Technical Paper

Comparison of ATD to PMHS Response in the Under-Body Blast Environment

2015-11-09
2015-22-0017
A blast buck (Accelerative Loading Fixture, or ALF) was developed for studying underbody blast events in a laboratory-like setting. It was designed to provide a high-magnitude, high-rate, vertical loading environment for cadaver and dummy testing. It consists of a platform with a reinforcing cage that supports adjustable-height rigid seats for two crew positions. The platform has a heavy frame with a deformable floor insert. Fourteen tests were conducted using fourteen PMHS (post mortem human surrogates) and the Hybrid III ATD (Anthropomorphic Test Device). Tests were conducted at two charge levels: enhanced and mild. The surrogates were tested with and without PPE (Personal Protective Equipment), and in two different postures: nominal (knee angle of 90°) and obtuse (knee angle of 120°). The ALF reproduces damage in the PMHS commensurate with injuries experienced in theater, with the most common damage being to the pelvis and ankle.
Journal Article

Design of a Multi-Chamber Silencer for Turbocharger Noise

2009-05-19
2009-01-2048
A multi-chamber silencer is designed by a computational approach to suppress the turbocharger whoosh noise downstream of a compressor in an engine intake system. Due to the significant levels and the broadband nature of the source spanning over 1.5 – 3.5 kHz, three Helmholtz resonators are implemented in series. Each resonator consists of a chamber and a number of slots, which can be modeled as a cavity and neck, respectively. Their target resonance frequencies are tuned using Boundary Element Method to achieve an effective noise reduction over the entire frequency range of interest. The predicted transmission loss of the silencer is then compared with the experimental results from a prototype in an impedance tube setup. In view of the presence of rapid grazing flow, these silencers may be susceptible to whistle-noise generation. Hence, the prototype is also examined on a flow bench at varying flow rates to assess such flow-acoustic coupling.
Technical Paper

Dynamic Properties of the Upper Thoracic Spine-Pectoral Girdle (UTS-PG) System and Corresponding Kinematics in PMHS Sled Tests

2012-10-29
2012-22-0003
Anthropomorphic test devices (ATDs) should accurately depict head kinematics in crash tests, and thoracic spine properties have been demonstrated to affect those kinematics. To investigate the relationships between thoracic spine system dynamics and upper thoracic kinematics in crash-level scenarios, three adult post-mortem human subjects (PMHS) were tested in both Isolated Segment Manipulation (ISM) and sled configurations. In frontal sled tests, the T6-T8 vertebrae of the PMHS were coupled through a novel fixation technique to a rigid seat to directly measure thoracic spine loading. Mid-thoracic spine and belt loads along with head, spine, and pectoral girdle (PG) displacements were measured in 12 sled tests conducted with the three PMHS (3-pt lap-shoulder belted/unbelted at velocities from 3.8 - 7.0 m/s applied directly through T6-T8).
Journal Article

Dynamic Stiffness of Hydraulic Bushing with Multiple Internal Configurations

2013-05-13
2013-01-1924
Fluid filled bushings are commonly used in vehicle suspension and sub-frame systems due to their spectrally-varying and amplitude-dependent properties. Since the literature on this topic is sparse, a controlled laboratory prototype bushing is first designed, constructed, and instrumented. This device provides different internal combination of long and short flow passages and flow restriction elements. Experiments with sinusoidal displacement excitations are conducted on the prototype, and dynamic stiffness spectra along with fluid chamber pressure responses are measured. The frequency-dependent properties of several commonly seen hydraulic bushing designs are experimentally studied and compared under two excitation amplitudes. Further, new linear time-invariant models with one long and one short flow passages (in parallel or series) are proposed along with the limiting cases.
Technical Paper

Effect of Intake Primary Runner Blockages on Combustion Characteristics and Emissions with Stoichiometric and EGR-diluted Mixtures in SI Engines

2007-10-29
2007-01-3992
In-cylinder charge motion is known to significantly increase turbulence intensity, accelerate combustion rate, and reduce cyclic variation. This, in turn, extends the tolerance to exhaust gas recirculation (EGR), while the introduction of EGR results in much lowered nitrogen oxide (NOx) emissions and reduced fuel consumption. The present study investigates the effect of charge motion in a spark ignition engine on fuel consumption, combustion, and engine-out emissions with stoichiometric and EGR-diluted mixtures under part-load operating conditions. Experiments have been performed with a Chrysler 2.4L 4-valve I4 engine under 2.41 bar brake mean effective pressure at 1600 rpm over a spark range around maximum brake torque timing. The primary intake runners are partially blocked to create different levels of tumble, swirl, and cross-tumble (swumble) motion in the cylinder before ignition.
Journal Article

Effect of the Tooth Surface Waviness on the Dynamics and Structure-Borne Noise of a Spur Gear Pair

2013-05-13
2013-01-1877
This article studies the effects of tooth surface waviness and sliding friction on the dynamics and radiated structure-borne noise of a spur gear pair. This study is conducted using an improved gear dynamics model while taking into account the sliding frictional contact between meshing teeth. An analytical six-degree-of-freedom (6DOF) linear time varying (LTV) model is developed to predict system responses and bearing forces. The time varying mesh stiffness is calculated using a gear contact mechanics code. A Coulomb friction model is used to calculate the sliding frictional forces. Experimental measurements of partial pressure to acceleration transfer functions are used to calculate the radiated structure-borne noise level. The roles of various time-varying parameters on gear dynamics are analyzed (for a specific example case), and the predictions from the analytical model are compared with prior literature.
Technical Paper

Engine and Load Torque Estimation with Application to Electronic Throttle Control

1998-02-23
980795
Electronic throttle control is increasingly being considered as a viable alternative to conventional air management systems in modern spark-ignition engines. In such a scheme, driver throttle commands are interpreted by the powertrain control module together with many other inputs; rather than directly commanding throttle position, the driver is now simply requesting torque - a request that needs to be appropriately interpreted by the control module. Engine management under these conditions will require optimal control of the engine torque required by the various vehicle subsystems, ranging from HVAC, to electrical and hydraulic accessories, to the vehicle itself. In this context, the real-time estimation of engine and load torque can play a very important role, especially if this estimation can be performed using the same signals already available to the powertrain control module.
Technical Paper

Errors Associated with Transfer Path Analysis when Rotations are not Measured

2007-05-15
2007-01-2179
Previously we had found significant errors in the interfacial force results for a source-path-receiver system where only translational motions were measured. This paper examines the sources of those errors by using computational finite and boundary element models. The example case consists of a source structure (with few modes), a receiver (with many modes) and three steel rod paths. We first formulate indirect, yet exact, methods for estimating interfacial forces, by assuming that six-dimensional motions at any location are available though we focus on only the driving points. One- and three-dimensional sub-sets of the proposed formulation are compared with the six-dimensional theory in terms of interfacial force and partial sound pressure spectra.
Technical Paper

Evaluation of the Kinematic Responses and Potential Injury Mechanisms of the Jejunum during Seatbelt Loading

2015-11-09
2015-22-0009
High-speed biplane x-ray was used to research the kinematics of the small intestine in response to seatbelt loading. Six driver-side 3-point seatbelt simulations were conducted with the lap belt routed superior to the pelvis of six unembalmed human cadavers. Testing was conducted with each cadaver perfused, ventilated, and positioned in a fixed-back configuration with the spine angled 30° from the vertical axis. Four tests were conducted with the cadavers in an inverted position, and two tests were conducted with the cadavers upright. The jejunum was instrumented with radiopaque markers using a minimally-invasive, intraluminal approach without inducing preparation-related damage to the small intestine. Tests were conducted at a target peak lap belt speed of 3 m/s, resulting in peak lap belt loads ranging from 5.4-7.9 kN. Displacement of the radiopaque markers was recorded using high-speed x-ray from two perspectives.
Technical Paper

IN-FLIGHT MEASUREMENTS OF THE GA(W)-2 AERODYNAMIC CHARACTERISTICS

1977-02-01
770461
Flight tests of a new 13% General Aviation Airfoil - the GA(W)-2 - gloved full span onto the existing wing of a Beech Sundowner have generated chordwise pressure distributions and wake surveys. Section lift, drag and moment coefficients derived from these measurements verify wind tunnel data and theory predicting the performance of this airfoil. The effect of steps, rivets and surface coatings upon the drag of the GA(W)-2 was also evaluated.
Technical Paper

Impact of Tumble on Combustion in SI Engines: Correlation between Flow and Engine Experiments

2007-10-29
2007-01-4003
The introduction of tumble into the combustion chamber is an effective method of enhancing turbulence intensity prior to ignition, thereby accelerating the burn rates, stabilizing the combustion, and extending the dilution limit. In this study, the primary intake runners are partially blocked to produce different levels of tumble motion in the cylinder during the air induction process. Experiments have been performed with a Chrysler 2.4L 4-valve I4 engine at maximum brake torque timing under two operating conditions: 2.41 bar brake mean effective pressure (BMEP) at 1600 rpm, and 0.78 bar BMEP at 1200 rpm. A method has been developed to quantify the tumble characteristics of blockages under steady flow conditions in a flow laboratory, by using the same cylinder head, intake manifold, and tumble blockages from the engine experiments.
Journal Article

Instabilities at the Low-Flow Range of a Turbocharger Compressor

2013-05-13
2013-01-1886
The acoustic and performance characteristics of an automotive centrifugal compressor are studied on a steady-flow turbocharger test bench, with the goal of advancing the current understanding of compression system instabilities at the low-flow range. Two different ducting configurations were utilized downstream of the compressor, one with a well-defined plenum (large volume) and the other with minimized (small) volume of compressed air. The present study measured time-resolved oscillations of in-duct and external pressure, along with rotational speed. An orifice flow meter was incorporated to obtain time-averaged mass flow rate. In addition, fast-response thermocouples captured temperature fluctuations in the compressor inlet and exit ducts along with a location near the inducer tips.
Technical Paper

Response of Neck Muscles to Rear Impact in the Presence of Bracing

2006-07-04
2006-01-2369
In this research, cervical muscle behavior in rear impact accidents was investigated. Specifically, cervical muscle forces and muscle lengthening velocities were investigated with respect to cervical injuries. Variation of the onset time for muscle activation, variation of muscle activation level and variation of rear impact pulses were considered. The human body simulation computer program, MADYMO and anthropometric numerical human model were used to evaluate the neck. The factors mentioned above were examined with specific data being obtained from several different literature sources. Cervical muscles were separated into three groups, the sternocleidomastoideus, the flexor muscle group and the extensor muscle group. Longuscolli and spleniuscapitis were selected to represent the flexor muscle and extensor muscle groups respectively. The values and trends of the muscle forces and lengthening velocities are investigated in each muscle group.
Technical Paper

Response of the 6-Month-Old CRABI in Forward Facing and Rear Facing Child Restraints to a Simulated Real World Impact

2002-03-04
2002-01-0026
It is commonly recommended to use infant/child restraints in the rear seat, and that until an infant reaches certain age, weight and height criteria, the infant restraint should be placed rear facing. This paper will describe the injuries suffered by an infant that was restrained in a forward-facing child seat placed in the front passenger seating position during a real world collision. Based on this collision, a full-scale vehicle to barrier impact test was performed. For this test, two 6-month-old CRABI dummies were used in identical child restraints. One of the restraints was placed in the front passenger seat in a forward facing configuration, and the other was placed in the right rear seating position in a rear-facing configuration. This paper provides a detailed discussion of the results of this test, including comparisons of the specific kinematics for both the restraint/child dummy configurations.
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