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Camless Variable Valve Actuation (VVA) technologies have been known for improving fuel economy, reducing emissions, and enhancing engine performance. VVA can be divided into electro-magnetic, electro-hydraulic, and electro-pneumatic actuation. A family of camless VVA designs (called LGD-VVA or Gongda-VVA) has been presented in an earlier SAE publication (SAE 2007-01-1295) that consists of a two-spring actuation, a bypass passage, and an electrohydraulic latch-release mechanism. The two-spring pendulum system is used to provide efficient conversion between the moving mass kinetic energy and the spring potential energy for reduced energy consumption and to be more robust to the operational temperature than the conventional electrohydraulic actuation; and the electrohydraulic mechanism is intended for latch-release function, energy compensation and seating velocity control.

Injury to the lower extremity during an automotive crash is a significant problem. While the introduction of safety features (i.e. seat belts, air bags) has significantly reduced fatalities, lower extremity injury now occurs more frequently, probably for a variety of reasons. Lower extremity trauma is currently based on a bone fracture criterion derived from human cadaver impact experiments. These impact experiments, conducted in the 1960's and 70's, typically used a rigid impact interface to deliver a blunt insult to the 90° flexed knee. The resulting criterion states that 10 kN is the maximum load allowed at the knee during an automotive crash when certifying new automobiles using anthropomorphic dummies. However, clinical studies suggest that subfracture loading can cause osteochondral microdamage which can progress to a chronic and debilitating joint disease.

Lower extremity (knee) injury prediction resulting from impact trauma is currently based on a bone fracture criterion derived from experiments on predominantly aged cadavers. Subsequent experimental and theoretical studies indicate that more aged, pathological specimens require higher, not lower, loads to initiate bone fracture. This suggests that a bone fracture criterion based solely on aged specimens may not be representative of the current driving population. In the current study, we sought to determine if cadaver age, physical size, sex, baseline joint pathology, or patellar geometry correlated with fracture load. An analysis was made of data from previous impact experiments conducted on fifteen isolated cadaver knees using a consistent impact protocol. The protocol consisted of sequentially increasing the impact energy with a rigid interface until gross fracture. Gross bone fractures occurred at loads of 6.9±2.0 kN (range 3.2 to 10.6 kN) using this protocol.

The identification/localization of propulsion noise in turbo machinery plays an important role in its design and in noise mitigation techniques. Near field acoustic holography (NAH) is the process by which all aspects of the sound field can be reconstructed based on sound pressure measurements in the near field domain. Identification of noise sources, particularly in turbo-machinery applications, efficiently and accurately is difficult due to complex noise generation mechanisms. Backward prediction of the sound field closer to the source than the measurement plane is typically an unstable “ill-posed” inverse problem due to the presence of measurement noise. Therefore regularized inversion techniques are typically implemented for noise source reconstruction. Another major source of ill-posedness in NAH inverse problems is a larger number of unknowns (sources) than available pressure measurements. A model reduction technique is proposed in this paper to address this issue.

Injuries to the lower extremities are common during car accidents because the lower extremity is typically the first point of contact between the occupant and the car interior. While injuries to the knee, ankle and hip are usually not life threatening, they can represent a large societal burden through treatment costs, lost work days and a reduced quality of life. The aim of the current study was to specifically study injuries associated with the knee and to propose a methodology which could be used to prevent future knee injuries. To understand the scope of this problem, a study was designed to identify injury trends in car crashes for the years 1979-1995. The NASS (National Accident Sampling System) showed that 10% of all injuries were to the knee, second only to head and neck injuries. Most knee injuries resulted from knee-to-instrument panel contact. Subfracture injuries were most common (contusions, abrasions, lacerations) followed by gross fracture injuries.

Extensive crash sled testing and analysis has recently led to the development of a new HANS prototypes for use in FIA F1. The performance of HANS prototypes has been studied with various conditions of HANS design geometry and impact direction. The new HANS prototypes have been found to substantially reduce injurious motions and forces of the head and neck, and the new HANS is lighter, more compact, and performs better than the currently available HANS. Use of HANS by FIA F1 drivers has been initiated.

In an effort to create computer models to promote rapid, cost-effective prototyping while easing design changes, more information about how people interact with seats is needed. Predicting the occupant location, their geometry, and motion within a vehicle leads to a better determination of safety restraint location, controls reach, and visibility - factors that affect the overall operation of the vehicle. Based on the Michigan State University JOHN model, which provides a biomechanical simulation of the torso posture, experiments were conducted to examine the change of postures due to seat and interior package factors. The results can be incorporated into the posture prediction model of the RAMSIS program to give a more detailed prognosis of the spine curvature and refine the model-seat interactions. This paper will address findings of the experimental study with relation to model development.

A numerical study on the combustion of Methanol in a directly injected (DI) engine was conducted. The study considers the effect of the bowl-in-piston (BIP) geometry, swirl ratio (SR), and relative equivalence ratio (λ), on flame propagation and burn rate of Methanol in a 4-stroke engine. Ignition-assist in this engine was accomplished by a spark plug system. Numerical simulations of two different BIP geometries were considered. Combustion characteristics of Methanol under swirl and no-swirl conditions were investigated. In addition, the amount of injected fuel was varied in order to determine the effect of stoichiometry on combustion. Only the compression and expansion strokes were simulated. The results show that fuel-air mixing, combustion, and flame propagation was significantly enhanced when swirl was turned on. This resulted in a higher peak pressure in the cylinder, and more heat loss through the cylinder walls.

High frequency variations in crankcase pressure have been observed in Inline-four cylinder (I4) engines and an understanding of the causes, frequency and magnitude of these variations is helpful in the design and effective operation of various engine systems. This paper shows through a review and explanation of the physics related to engine operation followed by comparison to measured vehicle data, the relationship between crankcase volume throughout the engine cycle and the observed pressure fluctuations. It is demonstrated that for a known or proposed engine design, through knowledge of the key engine design parameters, the frequency and amplitude of the cyclic variation in crankcase pressure can be predicted and thus utilized in the design of other engine systems.

A direct-injection and spark-ignition single-cylinder engine with optical access to the cylinder was used for the combustion visualization study. Gasoline and ethanol-gasoline blended fuels were used in this investigation. Experiments were conducted to investigate the effects of fuel injection pressure, injection timing and the number of injections on the in-cylinder combustion process. Two types of direct fuel injectors were used; (i) high-pressure production injector with fuel pressures of 5 and 10 MPa, and (ii) low-pressure production-intent injector with fuel pressure of 3 MPa. Experiments were performed at 1500 rpm engine speed with partial load. In-cylinder pressure signals were recorded for the combustion analyses and synchronized with the high-speed combustion imaging recording. Visualization results show that the flame growth is faster with the increment of fuel injection pressure.

A multicomponent droplet evaporation model which discretizes the one-dimensional mass and temperature profiles inside a droplet with a finite volume method has been developed and implemented into a large-eddy simulation (LES) model for spray simulations. The LES and multicomponent models were used along with the KH-RT secondary droplet breakup model to simulate realistic fuel sprays in a closed vessel. The effect of various spray and ambient gas parameters on the liquid penetration length of different single component and multicomponent fuels was investigated. The numerical results indicate that the spray penetration length decreases non-linearly with increasing gas temperature or pressure and is less sensitive to changes in ambient gas conditions at higher temperatures or pressures. The spray models and LES were found to predict the experimental results for n-hexadecane and two multicomponent surrogate diesel fuels reasonably well.

Since the 1960's, automotive seats have been designed and evaluated with tools and procedures described in the SAE Recommended Practice J826. The SAE J826 design template and testing manikin each have a torso with a flat lower back shape and with a single joint at the H-point. The JOHN models provide a more anatomically detailed representation of human shape and movement. The articulations of the JOHN torso (pelvic, lumbar, and thoracic) segments are coupled so that their relative positions are determined by a single parameter related to spinal curvature. This paper describes the development and use of the JOHN biomechanical models for seating design.

The human torso includes three major segments, the thoracic (rib cage) segment, lumbar segment, and pelvic segment to which the thighs are attached. The JOHN model was developed to represent the positions and movements of these torso segments along with the head, arms, and legs. Using the JOHN model, a new seat concept has been developed to support and move with the torso segments and thighs. This paper describes the background of the biomechanically articulated chair (BAC) and the development of BAC prototypes. These BAC prototypes have been designed to move with and support the thighs, pelvis, and rib cage through a wide variety of recline angles and spinal curvatures. These motions have been evaluated with computer modeling and with initial experience of human subjects. Results from computer modeling and human subjects show that the BAC will allow a broad range of torso postures.

Driver and passenger comfort, as related to automotive seats, is a growing issue in the automotive industry. As this trend continues, automotive seat designers and developers are generating a greater need for more anthropometrically accurate tools to aid them in their work. One tool being developed is the JOHN software program that utilizes three-dimensional solid objects to represent humans in seated postures. Contours have been developed to represent the outside skin surfaces of three different body types in a variety of postures in the sagittal plane. These body types include: the small female, the average male, and the large male.

An experimental study has been conducted to quantify the velocity and pressure inside an idealized intake manifold of a motored internal combustion engine assembly. The aim of this work is to provide the real-time boundary conditions for more accurate multi-dimensional numerical simulations of complex in-cylinder flows in an internal combustion engine as well as the resultant in-cylinder flow patterns. The geometry of the intake manifold is simplified for this purpose. A hot-wire anemometer and a piezoresistive absolute pressure transducer are used to measure the velocity and pressure, respectively, over a plane inside the circular section of the intake manifold. In addition, pressure measurements are performed over an elliptical section near the intake port. Phase-averaged velocity and pressure profiles are then calculated from the instantaneous measurements. Experiments were performed at 900 and 1200 rpm engine speeds with wide open throttle.

This paper describes additional and more recent results from the DaimlerChrysler study of HANS that includes a sensitivity analysis of HANS performance to variations in crash dummy neck length and other impact test conditions. The objective of the tests was to determine the robustness of the HANS concept in a variety of conditions that might occur in actual use. The results show that the variations in test parameters do effect injury measures from the crash dummy, but HANS provides substantial reductions in injury potential in all cases compared to not using HANS. Also, no injuries were indicated with HANS.

Ignition delay, using a rapid compression machine (RCM), is defined as the time period between the end of compression and the maximum rate of pressure rise due to combustion, at a given compressed condition of temperature and pressure. The same compressed conditions can be reached by a variety of combinations of compression ratio, initial temperature, initial pressure, diluent gas composition, etc. It has been assumed that the value of ignition delay, for a given fuel and at a given set of compressed conditions, would be the same, irrespective of the variety of the above-mentioned combinations that were used to achieve the compressed conditions. In this study, a range of initial conditions and compression ratios are studied to determine their effect on ignition delay time and to show how ignition delay time can differ even at the same compressed conditions.

Spherically expanding flames are employed to measure the laminar flame speed of premixed iso-octane/air mixtures at elevated temperatures through both experiments and numerical simulations. Iso-octane (2,2,4-trimethlypentane) is an important gasoline primary reference fuel (PRF). While most studies on laminar burning velocity of iso-octane focus on low temperatures (less than 400 K), the experiments here were conducted in an optically accessible constant volume combustion chamber between 373 K-473 K, at a pressure of 1 bar, and from ϕ=0.8 to ϕ=1.6. The effect of diluent is investigated through the addition of 15% CO2 dilution in order to simulate the effect of exhaust gas recirculation. The decreased reactivity with diluent addition reduces mixture reactivity, which can reduce the propensity for knock in spark ignition engines. All laminar flame speeds were calculated using the constant pressure method enabled via schlieren visualization of the spherically propagating flame front.

There is a limited amount of data currently available on the acceleration and braking performances of school buses. This paper analyzes the braking performance of various Type A and Type C school buses with hydraulic and air brakes. The effect of ABS and Non-ABS systems as well as driver experience is discussed. A comparison with passenger car braking performance is presented. The acceleration of a school bus is also presented. Evaluations of “normal” and “rapid” accelerations are presented for Type A and Type B buses. A comparison with commonly used acceleration values for various vehicles is presented.