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An experimental study has been carried out to examine the influence of ring tan load and piston skirt modifications on piston assembly friction under motored engine conditions for initial temperatures of -20, 0 and 30°C and motoring speeds within the range 400 to 2000 rev/min. The study has been carried out using the block, crankshaft and pistons of a 2.4I, 4 cylinder diesel engine with a bore and stroke of 89.9mm and 94.6mm respectively. The pistons examined are typical of current designs for light duty diesels. A range of ring pack and piston skirt modifications have been tested, in each case as part of a complete piston assembly. The first changes produced reductions in fmep of between 5% and 38%. The reduction was due to improved skirt and ring pack designs in equal measure, each giving improvements of up to 20%. From this baseline eliminating the tan load of the piston rings was projected to give a further reduction in fmep of between 10% and 20%.

An experimental investigation has been carried out to compare the indicated performance and heat release characteristics of a DI diesel engine at compression ratios of 18.4:1 and 15.4:1. The compression ratio was changed by modifying the piston bowl volume; the bore and stroke were unchanged, and the swept volume was nominally 500cc. The engine is a single cylinder variant of modern design which meets Euro 4 emissions requirements. Work output and heat release characteristics for the two compression ratios have been compared at an engine speed of 300 rev/min and test temperatures of 10, -10 and -20°C. A more limited comparison has also been made for higher speeds representative of cold idle at one test temperature (-20°C). The reduction in compression ratio generally produces an increase in peak specific indicated work output at low speeds; this is attributable to a reduction in blowby and heat transfer losses and lower peak rates of heat release increasing cumulative burn.

Idle Combustion Stability has previously been difficult to predict prior to prototype engine development. This paper describes an empirical modeling approach to predicting upfront idle combustion stability. The model outputs are the combustion torque harmonic magnitudes and %LNV. The paper describes the modeling methodology and provides correlation results for different engine configurations.

A three-step process was developed to estimate fracture criteria for a human body model. The process was illustrated via example wherein skull fracture criteria were estimated for the Ford Human Body Model (FHBM)~a finite element model of a mid-sized human male. The studied loading condition was anterior-to-posterior, blunt (circular/planar) cylinder impact to the frontal bone. In Step 1, a conditional reference risk curve was derived via statistical analysis of the tests involving fractures in a recently reported dataset (Cormier et al., 2011a). Therein, Cormier et al., authors reported results for anterior-to-posterior dynamic loading of the frontal bone of rigidly supported heads of male post mortem human subjects, and fracture forces were measured in 22 cases. In Step 2, the FHBM head was used to conduct some underlying model validations relative to the Cormier tests. The model-based Force-at-Peak Stress was found to approximate the test-based Fracture Force.

Torque controls for the engine and electric motors in a Powersplit HEV are keys to the success of balancing fuel economy, driveability, and battery power control. The electric variable transmission (EVT) offers an opportunity to let the engine operate at system-optimal fuel efficient points independently of any load. Existing work shows such a benefit can be realized through a decentralized control structure that translates the driver inputs to independent engine torque and speed control. However, our study shows that the decentralized control structures have a fundamental limitation that arises from the nonminimum phase (NMP) zero in the transfer function from the driver power command to the generator torque change rate, and thus not only is it difficult to obtain smooth generator torque but also it can cause violations on battery power limits during transients. Additionally, it adversely affects the driveability due to the generator torque transients reflected at the ring gear.

Experimental studies have been undertaken on a single-cylinder HPCR diesel engine with a compression ratio of 15.5:1 to explore the effect of fuel injection strategy on cycle by cycle stability. The influence of the number, separation and quantity of pilot injections on the coefficient of variation of IMEP has been investigated at -20°C, 1000 rev/min, post-start idling conditions. Injection strategy and glow plug temperature trade-off has also been investigated at a range of soak temperatures. Up to four pilot injections have been used. For timing of the main injection near to the optimum, CoVIMEP values of 10% or better can be achieved. Closer spacing of injections improved stability and extended the range of timings to meet target stability. The best combinations of pilot number and pilot quantity varied with total fuel delivered.

Two combustion systems were developed and optimized for an engine for a power cylinder of 0.8-0.9L/cylinder. The first design was a re-entrant bowl concept which was based on the combustion system of a smaller engine with roughly 0.5L/cylinder. The second design was a chamfered bowl concept, a variant of a reentrant bowl that deliberately splits fuel between the bowl and the squish region. For each combustion system concept, nozzle tip protrusion, swirl, and nozzle configuration (number of holes, nozzle flow, and spray angle) were optimized. Several similarities between combustion system concepts were noted, including the optimal swirl and number of holes. The resulting optimums for each concept were compared. The chamfered combustion system was found to have better part-load emissions and fuel consumption tradeoffs. Full load performance was similar at low speed between the two combustion systems, but the reentrant combustion system had advantages at high engine speed and load.

A Ford 2.4-liter 115PS light-duty diesel engine was modified to allow solenoid control of the oil feed to the piston cooling jets, enabling these to be switched on or off on demand. The influence of the jets on piston temperatures, engine thermal state, gaseous emissions and fuel economy has been investigated. With the jets switched off, piston temperatures were measured to be between 23 and 88°C higher. Across a range of speed-load points, switching off the jets increased engine-out emissions of NOx typically by 3%, and reduced emissions of CO by 5-10%. Changes in HC were of the same order and were reductions at most conditions. Fuel consumption increased at low-speed, high-load conditions and decreased at high-speed, low-load conditions. Applying the results to the NEDC drive cycle suggests active on/off control of the jets could reduce engine-out emissions of CO by 6%, at the expense of a 1% increase in NOx, compared to the case when the jets are on continuously.

Reducing friction in crankshaft bearings during cold engine operation by heating the oil supply to the main gallery has been investigated through experimental investigations and computational modelling. The experimental work was undertaken on a 2.4l DI diesel engine set up with an external heat source to supply hot oil to the gallery. The aim was to raise the film temperature in the main bearings early in the warm up, producing a reduction in oil viscosity and through this, a reduction in friction losses. The effectiveness of this approach depends on the management of heat losses from the oil. Heat transfer along the oil pathway to the bearings, and within the bearings to the journals and shells, reduces the benefit of the upstream heating.

Internal combustion (IC) engines fueled by hydrogen are among the most efficient means of converting chemical energy to mechanical work. The exhaust has near-zero carbon-based emissions, and the engines can be operated in a manner in which pollutants are minimal. In addition, in automotive applications, hydrogen engines have the potential for efficiencies higher than fuel cells.[1] In addition, hydrogen engines are likely to have a small increase in engine costs compared to conventionally fueled engines. However, there are challenges to using hydrogen in IC engines. In particular, efficient combustion of hydrogen in engines produces nitrogen oxides (NOx) that generally cannot be treated with conventional three-way catalysts. This work presents the results of experiments which consider changes in direct injection hydrogen engine design to improve engine performance, consisting primarily of engine efficiency and NOx emissions.

New emissions certification requirements for medium duty vehicles (MDV) meeting chassis dynamometer regulations in the 8,500 lb to 14,000 lb weight classes as well as heavy duty (HD) engine dynamometer certified applications in both the under 14,000 lb and over 14,000 lb weight classes employing large diameter exhaust pipes (up to 4″) have created new exhaust stream sampling concerns. Current On-Board-Diagnostic (OBD) dyno certified particulate matter (PM) requirements were/are 7x the standard for 2010-2012 applications with a planned phase in down to 3x the standard by 2017. Chassis certified applications undergo a similar reduction down to 1.75x the standard for 2017 model year (MY) applications. Failure detection of a Diesel Particulate Filter (DPF) at these low detection limits facilitates the need for a particulate matter sensor.

Tappet/bore friction and torque at the camshaft were measured for a direct acting bucket tappet using a cam/tappet friction apparatus. Tappet/bore and cam/tappet friction torque and friction coefficient as a function of cam angle were derived from those measurements. The results showed that, for the particular geometry tested, tappet/bore friction torque accounted for about 13% of the total cam/tappet/bore friction torque at 250 cam rpm. This fraction decreased with increasing speed. Tappet bore friction was greatest at about ± 40 degrees of cam angle, where side loads on the tappet bore were highest. In contrast, earlier results for a center pivot rocker arm design showed tappet bore friction to be negligible.

Two-stroke gasoline engines are known to benefit from using in-cylinder fuel injection which improves their ability to meet the strict fuel economy and exhaust emissions requirements. A conventional method of in-cylinder fuel injection involves application of plunger-type positive displacement pumps. Two-stroke engines are usually smaller and lighter than their 4-stroke counterparts of equal power and need a pump that should also be small and light and, preferably, simple in construction. Because a 2-stroke engine fires every crankshaft revolution, its fuel injection pump must run at crankshaft speed (twice the speed of a 4-stroke engine pump). An electronically controlled fuel injection system has been designed to satisfy the needs of a small automotive 2-stroke engine capable of running at speeds of up to 6000 rpm.

Ford is introducing the first high volume domestically designed and produced overhead camshaft V-8 engine As the first entry of a family of V-8 engines, the 4.6L 2 valve per cylinder engine was created to replace Ford's work-horse small block V-8 family of pushrod engines. That family of engines was first produced in 1962 in a 221 cu. in. version and have since evolved into the 302 cu. in. (5.0L) engine which previously powered the Town Car. Design goals of the engine family were: Higher horsepower output combined with reduced engine displacement Improved fuel efficiency and reduced emissions Reduced noise and vibration Advanced technology Precision manufacturing Improved quality and durability Program Execution was accomplished by extensive use of teamwork processes, including Cross Functional Teams (CFTs) among Design Engineering, Manufacturing Engineering, Suppliers, Purchasing and Vehicle Engineering.

Vehicle sound quality has become an important basic performance requirement. Traditionally, automobile noise studies were focused on quietness. It is now necessary for the automobile to be more than quiet. The sound must be pleasing. This paper describes a development process to improve both vehicle noise level and sound quality. Formal experimental design techniques were utilized to quantify various hardware effects. A-weighted sound pressure level, Speech Intelligibility, and Composite Rating of Preference were the three descriptors used to characterize the vehicle's sound quality. Engineering knowledge augmented with graphical and statistical techniques were utilized during data analysis. The individual component contributions to each of the sound quality descriptors were also quantified in this study.

Powder metal based copper steels have found increased use in automotive applications, an example being powder-forged connecting rods. A characterization study was conducted to determine the effects of carbon content and manganese sulphide addition on the mechanical properties and machinability of these materials. Steel powder mixes containing 2% Cu and various graphite contents, with and without a MnS addition were pressed, sintered and forged to full density. Forged samples were then tested for tensile properties, hardness and fatigue strength. Machinability was determined by measuring tool life during drilling tests. It was found that increasing the carbon content from 0.28 to 0.69% has little effect on fatigue properties of powder-forged copper steels although the tensile, strength increased as expected. The addition of manganese sulphide did not affect the mechanical properties measured, but was found to significantly improve the machinability.

The recent developments in diesel fuel injection equipment coupled with the moves in the US to using ULSD and biodiesel blends has seen an increase in the number of reports from both engine manufacturers and fleet operators regarding fuel system deposit formation issues. These deposits not only form on and within the fuel injectors but they also form elsewhere in the fuel system, due to fuel recirculation. These will eventually accumulate in the fuel filters. Historically, diesel fuel system deposits have been attributed to contamination of the fuel or the degradation of the fuel with age. Such age related degradation has been attributed to oxidation of the fuel via well documented pathways, although the initiation of this process is still poorly understood. Papers at recent SAE meetings in Florence, San Antonio, Rio de Janeiro, San Diego and Kyoto have addressed many of these causes.

The Leaner Lifted-Flame Combustion (LLFC) strategy offers a possible alternative to low temperature combustion or other globally lean, premixed operation strategies to reduce soot directly in the flame, while maintaining mixing-controlled combustion. Adjustments to fuel properties, especially fuel oxygenation, have been reported to have potentially beneficial effects for LLFC applications. Six fuels were selected or blended based on cetane number, oxygen content, molecular structure, and the presence of an aromatic hydrocarbon. The experiments compared different fuel blends made of n-hexadecane, n-dodecane, methyl decanoate, tri-propylene glycol monomethyl ether (TPGME), as well as m-xylene. Several optical diagnostics have been used simultaneously to monitor the ignition, combustion and soot formation/oxidation processes from spray flames in a constant-volume combustion vessel.

Natural luminosity (NL) and chemiluminescence (CL) imaging diagnostics are employed to investigate fuel-property effects on mixing-controlled combustion, using select research fuels-a #2 ultra-low sulfur emissions-certification diesel fuel (CF) and four of the Fuels for Advanced Combustion Engines (FACE) diesel fuels (F1, F2, F6, and F8)-that varied in cetane number (CN), distillation characteristics, and aromatic content. The experiments were performed in a single-cylinder heavy-duty optical compression-ignition (CI) engine at two injection pressures, three dilution levels, and constant start-of-combustion timing. If the experimental results are analyzed only in the context of the FACE fuel design parameters, CN had the largest effect on emissions and efficiency.

During the 1980s, the U.S. Environmental Protection Agency (EPA) incorporated the R factor into fuel economy calculations in order to address concerns about the impacts of test fuel property variations on corporate average fuel economy (CAFE) compliance, which is determined using the Federal Test Procedure (FTP) and Highway Fuel Economy Test (HFET) cycles. The R factor is defined as the ratio of the percent change in fuel economy to the percent change in volumetric heating value for tests conducted using two differing fuels. At the time the R-factor was devised, tests using representative vehicles initially indicated that an appropriate value for the R factor was 0.6. Reassessing the R factor has recently come under renewed interest after EPA's March 2013 proposal to adjust the properties of certification gasoline to contain significant amounts of ethanol.