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Technical Paper

Why Not Convert to Ductile Iron?

Cast iron is generally thought of as a weak, dirty, cheap, brittle material that does not have a place in applications requiring high strength and defined engineering properties. While gray cast iron is relatively brittle by comparison with steel, ductile iron is not. In fact, ductile iron has strengths and toughness very similar to steel and the machinability advantages make an attractive opportunity for significant cost reductions. Gray and ductile iron bar stock is commercially available and can be used as a direct replacement in applications that are currently being made from carbon steel bar. Ductile iron bar stock conversions are very prevalent in many fluid power applications including glands and rod guides, cylinders, hydrostatic transmission barrels and in high-pressure manifolds. Automotive gears are being converted to ductile iron for its damping capacity and cost reductions.
Technical Paper

Wear of Bearing Materials

Wear characteristics of four bearing materials have been investigated under different sliding conditions. The bearing materials used were CDA 954, CDA 863, CDA 932, and CDA 938. Using a Taber Wear Tester, a cylinder on a flat geometry was used as a tribo contact pair. All bearing materials in the form of a thick cylindrical disk were subjected to combined sliding-rolling motion against a rotating flat disk. The flat disk was either an abrasive disk, or a very soft steel disk, or a hardened steel disk with and without lubrication. Wear was measured as weight loss after several thousand cycles of rotation. Maximum wear of the bearing materials occurred when the counter body was a very soft steel disk. These results together with the wear rate of each bearing material sliding against four different counter bodies are presented. These results are found to be of practical importance in the design and application of journal bearings made of materials used in this investigation.
Journal Article

Virtual Cylinder Pressure Sensor for Transient Operation in Heavy-Duty Engines

Cylinder pressure-based combustion control is widely introduced for passenger cars. Benefits include enhanced emission robustness to fuel quality variation, reduced fuel consumption due to more accurate (multi-pulse) fuel injection, and minimized after treatment size. In addition, it enables the introduction of advanced, high-efficient combustion concepts. The application in truck engines is foreseen, but challenges need to be overcome related to durability, increased system costs, and impact on the cylinder head. In this paper, a new single cylinder pressure sensor concept for heavy-duty Diesel engines is presented. Compared to previous studies, this work focuses on heavy-duty Diesel powertrains, which are characterized by a relatively flexible crank shaft in contrast to the existing passenger car applications.

Vehicle Application Layer

The SAE J1939 communications network is developed for use in heavy-duty environments and suitable for horizontally integrated vehicle industries. The SAE J1939 communications network is applicable for light-duty, medium-duty, and heavy- duty vehicles used on-road or off-road, and for appropriate stationary applications which use vehicle derived components (e.g., generator sets). Vehicles of interest include, but are not limited to, on-highway and off-highway trucks and their trailers, construction equipment, and agricultural equipment and implements. SAE J1939-71 Vehicle Application Layer is the SAE J1939 reference document for the conventions and notations that specify parameter placement in PGN data fields, the conventions for ASCII parameters, and conventions for PGN transmission rates. This document previously contained the majority of the SAE J1939 data parameters and messages for information exchange between the ECU applications connected to the SAE J1939 communications network.
Technical Paper

Variable Swirl Inlet System and Its Effect on Diesel Performance and Emissions

A variable swirl inlet system with swirl control subport was developed with consideration of how to control the angular momentum of inlet flow into the cylinder. The effects of swirl on direct injection diesel engine performance and emissions are investigated with this variable swirl system. Basically, lower swirl level reduces the amount of initial stage burning, which is related to NOx emission, maximum cylinder pressure and rate of cylinder pressure rise, over the entire range of engine speed and load. As a result, in high speed range or partial load range, low swirl level simultaneously gives better BSFC and lower NOx level. An intercooled turbocharged engine with this variable swirl inlet system gave higher low-speed torque, higher brake horse power and better cold startability by selection of optimum swirl level for each engine condition.
Technical Paper

Validation of a Sparse Analytical Jacobian Chemistry Solver for Heavy-Duty Diesel Engine Simulations with Comprehensive Reaction Mechanisms

The paper presents the development of a novel approach to the solution of detailed chemistry in internal combustion engine simulations, which relies on the analytical computation of the ordinary differential equations (ODE) system Jacobian matrix in sparse form. Arbitrary reaction behaviors in either Arrhenius, third-body or fall-off formulations can be considered, and thermodynamic gas-phase mixture properties are evaluated according to the well-established 7-coefficient JANAF polynomial form. The current work presents a full validation of the new chemistry solver when coupled to the KIVA-4 code, through modeling of a single cylinder Caterpillar 3401 heavy-duty engine, running in two-stage combustion mode.
Technical Paper

Utilizing Multiple Combustion Modes to Increase Efficiency and Achieve Full Load Dual-Fuel Operation in a Heavy-Duty Engine

Reactivity Controlled Compression Ignition (RCCI) natural gas/diesel dual-fuel combustion has been shown to achieve high thermal efficiency with low NOX and PM emissions, but has traditionally been limited to low to medium loads. High BMEP operation typically requires high substitution rates (i.e., >90% NG), which can lead to high cylinder pressure, pressure rise rates, knock, and combustion loss. In previous studies, compression ratio was decreased to achieve higher load operation, but thermal efficiency was sacrificed. For this study, a multi-cylinder heavy-duty engine that has been modified for dual-fuel operation (diesel direct-injection and natural gas (NG) fumigated into the intake stream) was used to explore RCCI and other dual-fuel combustion modes at high compression ratio, while maintaining stock lug curve capability (i.e., extending dual-fuel operation to high loads where conventional diesel combustion traditionally had to be used).
Technical Paper

Using CONCHAS-Spray to Simulate the Process of a Methanol Fueled, Direct Injection Engine

The compression, combustion, and expansion portions of a two-stroke cycle, direct methanol injection engine was simulated using the CONCHAS-Spray computer code. The input and comparison data was supplied from a Detroit Diesel Allison production engine operating on methanol fuel. Calculated values of both cranking and firing chamber pressure were lower than reported from the engine. The injected fuel did not entirely evaporate which caused regions of fuel impinging on the cylinder walls and piston face. The simulation did predict the formation and accumulation of formaldehyde in the regions of unburned fuel and is consistent with the theory that the formaldehyde does not readily decompose at low temperatures and forms from the incomplete oxidation of the fuel.
Technical Paper

Unconventional Truck Chassis Design with Multi-Functional Cross Members

An unconventional conceptual design of truck chassis with multi-functional cross-members is proposed, and an optimization framework is developed to optimize its structure to minimize mass while satisfying stiffness and modal frequency constraints. The side rails are C-sectional channels of variable height and were divided into six sections, each with different thickness distribution for the flanges and the web. The gearbox cross-member and the intermediate cross-members are compressed-air cylinders, and hence they act as multi-functional components. The dimensions and thickness of the side rails and the air-tank cross members are defined by a set of parameters which are considered as design variables in the optimization problem. The structure consists of three additional fixed cross-members which are modeled using beam elements. The limits of the design variables are decided while considering manufacturing limits.
Technical Paper

Two-Color Combustion Visualization of Single and Split Injections in a Single-Cylinder Heavy-Duty D.I. Diesel Engine Using an Endoscope-Based Imaging System

An experimental study of luminous combustion in a modern diesel engine was performed to investigate the effect of injection parameters on NOX and soot formation via flame temperature and soot KL factor measurements. The two-color technique was applied to 2-D soot luminosity images and area-averaged soot radiation signals to obtain spatially and temporally resolved flame temperature and soot KL factor. The imaging system used for this study was based on a wide-angle endoscope that was mounted in the cylinder head and allowed different views of the combustion chamber. The experiments were carried out on a single-cylinder 2.4 liter D.I. diesel engine equipped with an electronically controlled common-rail injection system. Operating conditions were 1600 rpm and 75% load. The two-color results confirm that retarding the injection timing causes lower flame temperatures and NOX emissions but increased soot formation, independent of injection strategy.
Technical Paper

Turbocharger Impact on Diesel Electric Powertrain Performance

When electrifying the powertrain, there arises an opportunity to revise the traditional turbocharging trade-off between fuel-economy and transient performance. With the help of electrification, it might be possible to make the trade-off in favor of fuel economy, since transient response can be improved by the electric machine. The paper investigates this trade-off by looking at three turbocharger selections. A conventionally dimensioned turbocharger, an efficiency optimized turbocharger with maintained flow capacity, and an efficiency optimized turbocharger with increased flow capacity. The concepts are evaluated on the following cases: stationary operation, engine tip-in performance, vehicle acceleration performance, and on road fuel economy performance. The investigation is based on a validated mean value engine model of a six cylinder inline CI engine, and on a validated driveline and vehicle model of a heavy-duty truck.
Technical Paper

Truck Integral Power Steering

Integral hydraulic power steering gears, similar in concept to those used on current passenger cars, are now being used on heavy and extra-heavy trucks. This integral gear concept combines the steering gear, the control valve, and the hydraulic power cylinder into one durable and reliable assembly. This paper describes how such a gear was especially designed for this application, how the design was proven by qualification tests, and how product integrity is maintained. It is shown how this integral hydraulic power steering gear satisfies the needs of the heavy truck industry.
Technical Paper

Trend and Origins of Particulate and Hydrocarbon Emission from a Direct-Injection Diesel Engine

A systematic study on particulate mass emission from a high-speed direct-injection diesel engine was conducted using a mini-dilution sampling method. Effects of fuel-air equivalence ratio, engine speed, injection timing, and swirl intensity are presented and discussed with special regard to soluble organic fraction (SOF) and hydrocarbons. Results show that these concentrations are greatly affected by ignition delay or by temperature level in the engine cylinder. As the sources of SOF and hydrocarbons, local and bulk quenching of the charge, interaction of the fuel spray with the combustion chamber walls, and slow thermal decomposition of fuel are considered and discussed. Among them, the significance of the fuel decomposition is pointed out, by separate experiments on a simulated engine by using an in-cylinder gas-sampling technique.
Technical Paper

Tractor Hitches and Hydraulic Systems-An Implement Designer’s Viewpoint

SINCE world war II, integral implements have become increasingly popular. According to the author, this ever-increasing popularity of integral instruments over the corresponding towed type can be attributed to the following factors: 1. Greater maneuverability of tractor and implement combination. 2. Better transporting characteristics of tractor and implement combination. 3. Lower-cost implements. 4. Ease of attachment and control. An implement designer’s viewpoint on tractor hitches and hydraulic systems is presented here. The author hopes that it will help to assure that tractors of the future will have common implement-to-hitch attaching points, so that a tractor may be used with a number of different makes and sizes of integral implements. He also points out that certain performance features are needed to make integral instruments even more popular.
Technical Paper

Torsional Stress Measurement on Valve Springs of a Heavy Duty Engine in Collaboration with Valve Lift

The intake and exhaust valve spring of a 12.7L heavy duty diesel engine was instrumented with torque/shear rosette type strain gages to measure torsional stresses applied on the springs under different engine operating conditions. The engine was tested with no load, partial load and full load conditions and the effect of engine brake switch loading operation on the springs is investigated. Additional measurement of the valve lift motion and the peak fire pressure values from exactly the same cylinder were conducted to better understand the exact timing of the forces applied on the spring. This study gave an insight to the design engineer to determine the dynamic safety margin of the spring under permissible torsional stress values and optimize the material type of the spring accordingly. Another achievement is to measure any possible unpredictable torsional stress values occurred during engine operation when the engine brake is turned on/off and correlate the CAE model.
Technical Paper

Time and Space Resolved Measurement of Air Motion in a Cylinder of Direct-Injection Diesel Engine

This paper describes information of the swirling flow in a direct-injection diesel engine which has over-head valves and a troidal cavity. The forward-scattering laser doppler velocimeter was used. The “SIDE VIEW” optical arrangement was adopted in the engine to measure the flow in the cylinder and in the cavity with little modification on the configuration of the combustion chamber. The properties of the swirling flow were discussed for three kinds of cylinder heads which produced different intake flows. As a result, the relationship between the mean velocity, the turbulence and the cycle-to-cycle variation was revealed. Further, the variation of the flow pattern and the swirl intensity was indicated as a function of the crank angle and the axial distance.
Technical Paper

Three-Dimensional Spray Distributions in a Direct Injection Diesel Engine

Experiments and modeling of a spray impinged onto a cavity wall of a simulated piston were performed under simulated diesel engine conditions (pressure and density) at an ambient temperature. The diesel fuel was delivered from a Bosch-type injection pump to a single-hole nozzle, the hole being drilled in the same direction as the original five-hole nozzle. The fuel was injected into a high-pressure bomb in which an engine combustion chamber, composed of a piston, a cylinder head and a cylinder liner, was installed. Distributions of the spray impinged on the simulated combustion chamber were observed from various directions while changing some of the experimental parameters, such as combustion chamber shape, nozzle projection and top-clearance. High-speed photography was used in the constant volume bomb to examine the effect of these parameters on the spray distributions.
Technical Paper

Thermal Loading of the Cylinder Head of a Divided - Chamber Diesel Engine

Time-averaged combustion chamber surface temperatures and surface heat fluxes were measured at three locations (one in the antechamber and two in the main chamber) on the head of a single-cylinder, divided-chamber diesel engine. In general the surface temperature and heat flux were found to increase with increasing engine speed, fuel-air ratio and intake-air temperature, decreasing coolant temperature and advancing combustion timing. At motored conditions the highest heat flux was at the antechamber location. This was caused by the high swirl flows present in the antechamber. In contrast, at all other conditions the highest heat flux was measured at the location in the main chamber near the valves. This was attributed to the convective action of the high-temperature stream of combustion gases exiting the antechamber during the expansion stroke. Lastly, the local surface heat flux measurements were correlated in terms of the air and fuel consumption rates of the engine.