Search Results

It is the purpose of this paper to make clear the effect of typical torsional viscous-friction damper on the reduction of the axial, torsional and two directions of lateral vibrations from the analytical and experimental points of view. At first, a typical type of the torsional viscous-friction damper is fitted to a high-speed diesel engine and the axial, torsional and two directions of lateral vibration displacements at the pulley end are measured in order to investigate the effect of the damper on the reduction of these vibrations in the three dimensional space of the engine shaftings from the experimental point of view. Next, the characteristics of the axial, torsional and two directions of lateral vibrations of the engine shaftings are investigated by three dimensional analysis of forced vibration by the transfer matrix method, which has been developed by the authors.

This paper investigates the response of the wheel slip to brake torque perturbations during a braking manoeuvre as the wheel slip state and the vehicle speed change. Its purpose is to better understand and model the wheel slip response characteristics during braking and to inform the development process of an antiskid wheel slip controller. The developed controller is implemented in the Simulink environment on a half-car vehicle model using a nonlinear electromechanical brake (EMB) model. A linearised analysis of the wheel slip response to brake torque perturbations about a nominal “trim” condition is first performed, based on a quarter-car vehicle model. It is shown that the inclusion of first-order tyre dynamics (characterised by the so-called “relaxation length”) has a significant effect on the dynamics of the “plant” seen by the slip controller and these dynamics vary significantly with the trim value of the slip and the vehicle speed.

A carburetor for a 1968 six-cylinder Ford engine was modified to meter gasoline into the engine through an ultrasonic horn. The engine, mounted on a test stand, was loaded by a water dynamometer. The tests were performed with the horn alternately activated and deactivated for two different tip configurations. Engine operating data were taken at five throttle positions and thermal efficiency and specific fuel consumption were determined for each of these positions. Marked improvement (5-10%) in these parameters was obtained at an ultrasonic power input of 20 watts.

A major trend in current automotive research is hybridization of the power supply. This combination of electrical machine and combustion engine results, in some hybridization topologies, in a total decoupling of the combustion engine from the transmission. When the engine is decoupled from the transmission a new degree of freedom arises in engine design. The piston movement does not have to follow an evenly rotating shaft any more. It can be altered by the generator to achieve a movement found to be better from the point of efficiency or environmental concerns. Modelling work showed a potential of lowered NO emissions if the expansion could be delayed. The experimental study, conducted in a two piston Alvar engine, showed that the state of the art electrical machine (EM) propelling one of the crankshafts was too weak to change the crankshaft speed in an extent to give the fast volume changes required to change the emissions of the internal combustion engine (ICE).

In order to explore approaches for improving object detection accuracy in intelligent vehicle system, we exploit super-resolution techniques. A novel method is proposed to confirm the conjecture whether some popular super-resolution networks used for environmental perception of intelligent vehicles and robots can indeed improve the detection accuracy. COCO dataset which contains images from complex ordinary environment is utilized for the verification experiment, due to it can adequately verify the generalization of each algorithm and the consistency of experimental results. Using two representative object detection networks to produce the detection results, namely Faster R-CNN and YOLOv3, we devise to reduce the impact of resizing operation. The two networks allow us to compare the performance of object detection between using original and super-resolved images. We quantify the effect of each super-resolution techniques as well.

Three cars have been operated for approximately 8000 miles on each of four unleaded gasolines. These gasolines encompassed varied levels of C6-C8 aromatics and varied polynuclear aromatic (PNA) content. Exhaust PNA emissions and lube oil PNA content were measured periodically during the course of mileage accumulation. Results of this study show that increases in both light C6-C8 fuel aromatics and fuel-contained PNAs can result in significantly increased exhaust PNAs. Vehicles meeting increasingly stringent hydrocarbon (HC) and carbon monoxide (CO) emissions standards emit greatly reduced quantities of exhaust PNAs, though the rate of lube oil PNA accumulation appears to be unaffected by emissions control systems. Accumulated lubricating oil mileage was found to correlate with increased PNA emissions with a high level of statistical significance. This may be the result of an observed increase in lube oil PNA content with mileage accumulation.

The knock behavior of two groups of unleaded gasolines, each of which includes three fuels with different chemical compositions but comparable standard octane numbers, has been analyzed using a mass-produced engine. The aim of the work was to point out possible inconsistencies between the standard octane numbers of the fuels and their knock behavior in mass-produced engines. The fuels of the first group had R.O.N.s and M.O.N.s very close to the minimum values required by European Community regulations (95 and 85, respectively), whereas the fuels of the second group had higher R.O.N.s and M.O.N.s (about 100 and 87.5, respectively). One of the tested fuels in the first group was a typical European unleaded gasoline, the other gasolines had higher olefin or aromatic contents. An increase of the aromatic content has not shown appreciable differences between the expected knock behavior of the fuel from its standard octane numbers, and its performance on the mass-produced engine.

Automotive engineers use the wind tunnel to improve a vehicle’s aerodynamic properties on the road. However, a car driving on the road does not experience the steady-state, uniform flow characteristic of the wind tunnel. Wind, terrain and traffic all cause the flow experienced by the vehicle to be highly transient. Therefore, it is imperative to understand the effects of forces acting on the vehicle resulting from unsteady flow. To this end, the FKFS swing® installed in the University of Stuttgart’s model scale wind tunnel was used to create 36 different incident flow signals with time-resolved yaw angles. The cD values of five different 25% vehicle models, each with a notchback and a squareback configuration, were measured while under the influence of the aforementioned signals. The vehicle models were chosen to ensure a variety of different geometries, but at the same time also to enable isolated comparison of specific geometric properties.

In the ECE 127 Regulation on pedestrian leg protection, as well as in the Euro NCAP test protocol, a legform impactor hits the vehicle at the speed of 40 kph. In these tests, the knee is fully extended and the leg is not coupled to the upper body. However, the typical configuration of a pedestrian impact differs since the knee is flexed during most of the gait cycle and the hip joint applies an unknown force to the femur. This study aimed at investigating the influence of the inertia of the upper body (modelled using an upper body mass fixed at the proximal end of the femur) and the initial knee flexion angle on the lower limb injury outcome. In total, 18 tests were conducted on 18 legs from 9 Post Mortem Human Subjects (PMHS). The principle of these tests was to impact the leg at 40 kph using a sled equipped with 3 crushing steel tubes, the stiffness of which were representative of the front face of a European sedan (bonnet leading edge, bumper and spoiler).

As open-wheeled racing cars frequently race in close proximity, a limiting factor on the ability to overtake is the aerodynamic performance of the vehicle while operating in a leading car's wake. Whilst various studies have examined the effectiveness of wings operating in turbulent flow, there has been limited research undertaken on the aerodynamic effect of such conditions on wheels. This study describes the influence of upstream turbulence on the wake flow features of an isolated wheel, since the flow field of a wheel will generally be turbulent (due to the wakes of upstream cars and/or bodywork). Pressure distributions and velocity vector plots are examined, which were obtained using a four-hole pressure-sensitive Cobra probe on a traverse 2.5 diameters downstream of the wheel axle line, in smooth and turbulent flow.

Currently, a majority of the ‘gasoline’ sold at the pumps in the United States is a nominal blend of 90% gasoline and 10% ethanol. This mixture is commonly referred to as E10. This paper reports on a study conducted to determine the effects of E10 on the fuel system performance of vintage automobiles. The study focused on the potential degradation in performance of the carburetors and fuel pumps due to exposure to E10. Six fuel systems were selected for study including the 1948 Flathead Ford, 1958 Volkswagen Beetle, 1962 Ford Falcon, 1969 Chevrolet Bel Air and 1970 Chrysler New Yorker. The components tested were either rebuilt original equipment or new aftermarket replacement parts, depending on availability. Although the components tested were not all original equipment parts, they represent a reasonable sample of the types of parts likely to be found in vintage vehicles currently on the road. The fuel system components were tested under both dynamic and static conditions.

This work was conducted to evaluate the effects resulting from the use of various VI improvers in multigrade engine oils on automobile oil economy. The test oils were formulated to be of similar viscosity in the SAE 5W-40 viscosity grade. The VI improvers tested covered a range of permanent shear stability, temporary shear stability and thickening characteristics. Engine oil volatility was the only variable which could be identified as having a significant effect on automobile oil economy. The oils containing the styrene/diene VI improver were less volatile than all other oils tested and provided statistically significant improvements in oil economy. Permanent shear stability, high temperature/high shear viscosity, and in-use (used-oil) viscosity could not be identified as having a significant effect on automobile oil economy of the SAE 5W-40 oils studied.

A number of Variable Valve Actuators (VVA) has been recently proposed to improve the performances and the part load efficiency of spark ignition engines. Due to their peculiarity, these systems work with different strategies (late or early inlet valve closing, reduced lift etc.). The shape and the timing of the valve lift affect not only the pumping losses, but also air motion inside the cylinder. That influences mixture formation and combustion evolution of Direct Injection Spark Ignition (DISI) engines. The present paper compares the performances of different VVA systems with the aid of a 1D code for the simulation of the inlet and of the exhaust phases, and of a fluid-dynamic 3D code to evaluate mixing phenomena inside the cylinder.

Validation of the Ford General Engine SIMulation program (GESIM) with measured firing data from a modified single cylinder Ricardo HYDRA research engine is described. GESIM predictions for peak cylinder pressure and burn duration are compared to test results at idle operating conditions over a wide range of valve overlap. The calibration of GESIM was determined using data from only one representative world-wide operating point and left unchanged for the remainder of the study. Valve overlap was varied by as much as 36° from its base setting. In most cases, agreement between model and data was within the accuracy of the measurements. A cycle simulation computer model provides the researcher with an invaluable tool for acquiring insight into the thermodynamic and fluid mechanical processes occurring in the cylinder of an internal combustion engine.

This study is focused on the effect of different valve strategies on the in-cylinder flow and combustion A conventional four-valve pentroof engine was modified to enable optical access to the combustion chamber To get information on the flow, a two-component LDV system was applied The combustion was monitored by the use of cylinder pressure in a one-zone heat release model The results show that the flow in the cylinder with the valves operating in the standard configuration has an expected tumble characteristic In this case the high frequency turbulence is homogeneous and has a peak approximately 20 CAD BTDC With one valve deactivated, the flow shows a swirling pattern The turbulence is then less homogeneous but the level of turbulence is increased When the single inlet valve was phased late against the crankshaft dramatic effects on the flow resulted The late inlet valve opening introduced a low cylinder pressure before the valve opened The high pressure difference across the valve introduced a high-velocity jet into the cylinder Turbulence was increased by a factor of two by this operational mode When two inlet valves were used, a reduction of turbulence resulted from a very late inlet cam phase

The aim of present work is to investigate the performance and emission characteristics of a four stroke, single cylinder variable compression ratio engine fuelled with blends of diethyl ether, linseed oil methyl ester and neat diesel. In the experiment content of diethyl ether kept constant as 5% by volume for all fuel samples whereas linseed methyl ester biodiesel content was varied as 10%, 15% and 20% by volume. The different fuel samples DLD15, DLD20 and DLD25 with neat standard diesel. Experiment tests were performed with engine speed 1500 rpm and variable compression ratio 16, 17 and 18 at different load conditions. The effect of blends and compression ratio on different performance parameters viz. brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and exhaust gas temperature along with emissions CO, CO2, HC and NOx, were investigated. Results showed that DLD20 and DLD25 exhibited the prominent engine performance and exhaust emissions compared to diesel fuel.

Several types of energy absorbers were tested on a sled simulating a crash deceleration using instrumented, seated erect dummies and cadavers. The energy absorbers were mechanical load limiting devices which attenuated the impact by yielding or tearing of metal. Their principal effects were to reduce the peak deceleration sustained by the occupant with the expected reduction in restraint forces. Constant load level energy absorbers were found to be unattractive because they can easily “bottom out” causing forces and body strains which could be much higher than those without absorbers. Head accelerations were significantly reduced by the energy absorbers as well as some body strain. However, spinal strains in the cadaver were not significantly reduced. They appear to be not only a function of the peak deceleration level but also of the duration of the pulse.

Thermodynamic, dynamic and design parameters have a significant and often conflicting impact on the transient response of a compression ignition engine. Knowing the contribution of each parameter on transient operation could direct the designer to the appropriate measures for better engine performance. To this aim an explicit simulation program developed is used to study the performance of a turbocharged diesel engine operating under transient load conditions. The simulation developed, based on the filling and emptying approach, provides various innovations as follows: Detailed analysis of thermodynamic and dynamic differential equations, on a degree crank angle basis, accounting for the continuously changing nature of transient operation, analysis of transient mechanical friction, and also a detailed mathematical simulation of the fuel pump. Each equation in the model is solved separately for every cylinder of the 6-cylinder diesel engine considered.

Speed-sensing Limited-Slip Differentials (LSD) such as Viscous Couplings (VC) are becoming major players in Front-Wheel Drive (FWD) applications. Traction Control Systems (TCS) which control the wheel slip by influencing the engine torque output and/or actuating the brakes are also introduced to the FWD market in growing numbers. A few applications for torque-sensing LSD's have recently entered the market. All of these devices are known mainly for their traction improvements. However, all systems have demonstrated that they also positively influence handling and stability even under normal driving conditions. This paper presents a series of proving ground tests which investigate the effects of speed-sensing and torque-sensing LSD's as well as TCS on traction, vehicle stability, handling and torque-steer. Factors affecting torque-steer are described and key vehicle design parameters are identified which greatly influence both the application and compatibility of LSD with FWD.

Due to limited fossil fuel resources and a need to reduce anthropogenic CO₂ emissions, biofuel usage is increasing in multiple markets. Ethanol produced from the fermentation of biomass has been of interest as a potential partial replacement for petroleum for some time; for spark-ignition engines, bioethanol is the alternative fuel which is currently of greatest interest. At present, the international market for ethanol fuel consists of E85 fuel (with 85 percent ethanol content), as well as lower concentrations of ethanol in petrol for use in standard vehicles (E5, E10). The impact of different petrol-ethanol blends on exhaust emissions from unmodified vehicles remains under investigation. The potential for reduced exhaust emissions, improved security of fuel supply and more sustainable fuel production makes work on the production and usage of ethanol and its blends an increasingly important research topic.