Search Results

In recent years, Nearfield Acoustical Holography (NAH) has been used to identify stationary vehicle exterior noise sources. However that application has usually been limited to individual components. Since powertrain noise sources are hidden within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial field that combine to create the complete exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address these concerns: it is described here. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. In the second part of this paper, the use of farfield arrays is considered. Several array techniques have previously been applied to identify noise sources on moving vehicles.

Fundamental understanding of the sources of fuel-derived Unburned Hydrocarbon (UHC) emissions in heavy duty diesel engines is a key piece of knowledge that impacts engine combustion system development. Current emissions regulations for hydrocarbons can be difficult to meet in-cylinder and thus after treatment technologies such as oxidation catalysts are typically used, which can be costly. In this work, Computational Fluid Dynamics (CFD) simulations are combined with engine experiments in an effort to build an understanding of hydrocarbon sources. In the experiments, the combustion system design was varied through injector style, injector rate shape, combustion chamber geometry, and calibration, to study the impact on UHC emissions from mixing-controlled diesel combustion.

Clutches are commonly utilised in passenger type and off-road heavy-duty vehicles to disconnect the engine from the driveline and other parasitic loads. In off-road heavy-duty vehicles, along with fuel efficiency start-up functionality at extended ambient conditions, such as low temperature and intake absolute pressure are crucial. Off-road vehicle manufacturers can overcome the parasitic loads in these conditions by oversizing the engine. Caterpillar Inc. as the pioneer in off-road technology has developed a novel clutch design to allow for engine downsizing while vehicle’s performance is not affected. The tribological behaviour of the clutch will be crucial to start engagement promptly and reach the maximum clutch capacity in the shortest possible time and smoothest way in terms of dynamics. A multi-body dynamics model of the clutch system is developed in MSC ADAMS. The flywheel is introducing the same speed and torque as the engine (represents the engine input to the clutch).

This paper reports on a comprehensive, crank-angle transient, three dimensional, computational fluid dynamics (CFD) model of the complete lubrication system of a multi-cylinder engine using the CFD software Simerics-Sys / PumpLinx. This work represents an advance in system-level modeling of the engine lubrication system over the current state of the art of one-dimensional models. The model was applied to a 16 cylinder, reciprocating internal combustion engine lubrication system. The computational domain includes the positive displacement gear pump, the pressure regulation valve, bearings, piston pins, piston cooling jets, the oil cooler, the oil filter etc… The motion of the regulation valve was predicted by strongly coupling a rigorous force balance on the valve to the flow.

Although soot-formation processes in diesel engines have been well characterized during the mixing-controlled burn, little is known about the distribution of soot throughout the combustion chamber after the end of appreciable heat release during the expansion and exhaust strokes. Hence, the laser-induced incandescence (LII) diagnostic was developed to visualize the distribution of soot within an optically accessible single-cylinder direct-injection diesel engine during this period. The developed LII diagnostic is semi-quantitative; i.e., if certain conditions (listed in the Appendix) are true, it accurately captures spatial and temporal trends in the in-cylinder soot field. The diagnostic features a vertically oriented and vertically propagating laser sheet that can be translated across the combustion chamber, where “vertical” refers to a direction parallel to the axis of the cylinder bore.

Nitrites have long been added to heavy-duty coolant to inhibit iron cylinder liner corrosion initiated by cavitation. However, in heavy-duty use, nitrites deplete from the coolant, which then must be refortified using supplemental coolant additives (SCA's). Recently, carboxylates have also been found to provide excellent cylinder liner protection in heavy-duty application. Unlike nitrites, carboxylate inhibitors deplete slowly and thus do not require continual refortification with SCA's. In the present paper laboratory aging experiments shed light on the mechanism of cylinder liner protection by these inhibitors. The performance of carboxylates, nitrites and mixtures of the two inhibitors are compared. Results correlate well with previously published fleet data. Specifically, rapid nitrite and slow carboxylate depletion are observed. More importantly, when nitrite and carboxylates are used in combination, nitrite depletion is repressed while carboxylates deplete at a very slow rate.

The automotive industry is dramatically changing. Many automotive Original Equipment Manufacturers (OEMs) proposed new prototype models or concept vehicles to promote a green vehicle image. Non-traditional players bring many latest technologies in the Information Technology (IT) industry to the automotive industry. Typical vehicle’s characteristics became wider compared to those of vehicles a decade ago, and they include not only a driving range, mileage per gallon and acceleration rating, but also many features adopted in the IT industry, such as usability, connectivity, vehicle software upgrade capability and backward compatibility. Consumers expect the latest technology features in vehicles as they enjoy in using digital applications in laptops and mobile phones. These features create a huge challenge for a design of a new vehicle, especially for a human-machine-interface (HMI) system.

Software systems on electronically controlled diesel truck engines typically provide diagnostic features to enable the engine mechanic to identify and debug system problems. As future systems become more sophisticated, so will the diagnostic requirements. The advantages of serviceability and accuracy found in todays electronic systems must not be allowed to degrade due to this increased sophistication. One method of maintaining a high level of serviceability and accuracy is to place an even greater priority on diagnostics and servicing in the initial design phase of the product than is done today. In particular, three major goals of future diagnostic systems should be separation of component failures from system failures, prognostication of failures and analysis of engine performance. This paper will discuss a system to realize these goals by dividing the diagnostic task into the Electronic System Diagnostics, Engine System Diagnostics and the Diagnostic Interface.

Off-highway machine mounting system isolation, especially the cab mounting system, significantly affects the operator comfort by providing damping to the harsh inputs and isolating the structure-borne energy from traveling into the cab. Mounting system isolation performance is decided not only by the isolation component, but also the mounting bracket structure, and should be treated as a system. This paper gives a review of how the mounting system isolates structural energy and the effect of the bracket structure stiffness to the mounting system isolation performance.

Boundary element analysis (BEA) is an effective computer simulation program for certain applications in design engineering. The BEA technique has been used extensively at Caterpillar for structural analysis of engine and vehicle components. The time savings and modeling ease of BEA are illustrated with specific examples of engine component models. These examples represent a variety of modeling techniques, and include comparisons with measured test data.

Lithium-ion batteries (LIBs) repurposed from retired electric vehicles (EVs) for grid-scale energy storage systems (ESSs) have the potential to contribute to a sustainable, low-carbon-emissions energy future. The economic and technological value of these “second-life” LIB ESSs must be evaluated based on their operation on the electric grid, which determines their aging trajectories. The battery research community needs experimental data to understand the operation of these batteries using laboratory experiments, yet there is a lack of work on experimental evaluation of second-life batteries. Previous studies in the literature use overly-simplistic duty cycling in order to age second-life batteries, which may not produce aging trajectories that are representative of grid-scale ESS operation. This mismatch may lead to inaccurate valuation of retired EV LIBs as a grid resource.

There has been an ongoing interest in replacing mineral oil with more biodegradable and/or fire-resistant hydraulic fluids in many mobile equipment applications. Although many alternative fluids may be more biodegradable, or fire-resistant, or both than mineral oil, they often suffer from other limitations such as poorer wear, oxidative stability, and yellow metal corrosion which inhibit their performance in high-pressure hydraulic systems, particularly high pressure piston pump applications. From the fluid supplier's viewpoint, the development of a definitive test, or series of tests, that provides sufficient information to determine how a given fluid would perform with various hydraulic components would be of interest because it would minimize extensive testing. This is often too slow or prohibitively expensive. Furthermore, from OEM's (original equipment manufacturer's) point of view, it would be advantageous to develop a more effective, industry accepted fluid analysis screening.

A slipstream of exhaust from a Caterpillar 3126B engine was diverted into a plasma-catalytic NOx control system in the space velocity range of 7,000 to 100,000 hr-1. The stream was first fed through a non-thermal plasma that was formed in a coaxial cylinder dielectric barrier discharge reactor. Plasma treated gas was then passed over a catalyst bed held at constant temperature in the range of 573 to 773 K. Catalysts examined consisted of γ-alumina, indium-doped γ-alumina, and silver-doped γ-alumina. Road and rated load conditions resulted in engine out NOx levels of 250 - 600 ppm. The effects of hydrocarbon level, catalyst temperature, and space velocity are discussed where propene and in one case ultra-low sulfur diesel fuel (late cycle injection) were the reducing agents used for NOx reduction. Results showed NOx reduction in the range of 25 - 97% depending on engine operating conditions and management of the catalyst and slipstream conditions.

Silicate-free, carboxylate based technology as typified by Texaco Extended Life Coolant (TELC) and Caterpillar Extended Life Coolant (ELC), both meeting Caterpillar's EC-1 Coolant Specification, offer excellent corrosion protection for commercial lead solders commonly used in the fabrication of copper/brass radiators and heater cores throughout the trucking industry. Results of laboratory testing using solders from commercial radiators manufacturers and extensive field coolant analysis compare extended life technology with the popular conventional coolant technologies. In the laboratory, the effect of coolant concentration on solder protection is explored using the glassware corrosion test, ASTM D-1384. At concentrations ranging from 33% up to 75% the carboxylate technology offers comparable to superior protection when compared to the popular heavy-duty conventional coolant containing silicates and phosphates.

The paper presents a method for shorter evaluation of the fatigue damage done by an irregular sequence of loads. The method looks first for the largest overall range from highest peak to lowest valley, then for the next largest overall range that interrupts the first range, and so on, down until a suitable fraction (for example, 10%) of all reversals have been used. These few reversals form a short history, which will do substantially the same damage as the total history. The process is applied to three long histories selected by the SAE Fatigue Design and Evaluation Committee. The sensitivity of calculated damage to the omission of smaller ranges is computed for plain and for notched specimens. The error is compared with differences produced by different current rules for evaluating damage, by different cycle counting methods, and by smooth specimen simulation of notched parts.

For high-load applications, natural gas represents a clean burning, readily available, and relatively inexpensive alternative to number 2 Diesel fuel. However, the fuel’s poor ignitability has previously limited implementation to spark ignited and dual-fueled engines. These approaches suffer from reduced peak load and high engine-out particulate emissions, respectively, requiring lean operation and expensive aftertreatment to meet regulatory standards. A high-temperature combustion strategy can overcome the difficult ignitibility, allowing for true Diesel-style combustion of pure methane-the least ignitable and least sooting component of natural gas. In order to achieve this result, a compression system was designed to supply fuel at pressures suitably high to achieve good mixing and short injection durations, and a solenoid-actuated Diesel fuel injector was modified to function at these pressures with a gaseous fuel.

This paper presents predictions of fatigue crack initiation life for three distinctly different, irregular load histories, each applied to keyhole-notched compact tension specimens at several maximum load levels and using two different structural steels. Work leading to this paper was done in conjunction with the cooperative research program of the SAE Fatigue Design and Evaluation Committee. Three computerized prediction methods (Landgraf, Wetzel, and a Nominal Stress Range approach) are used. All predictions are based on load histories condensed to 10% of their original number of reversals by the “Racetrack Method.” This method, which is described in detail, selects the most damaging overall ranges in an irregular load history while preserving the sequence of the original loading. Predictions are compared with test data for the two dozen combinations of loading type and level and steel used. Comments are made on the relative merits of the different prediction methods.

Diesel engine downsizing aimed at reducing fuel consumption while meeting stringent exhaust emissions regulations is currently in high demand. The boost system architecture plays an essential role in providing adequate air flow rate for diesel fuel combustion while avoiding impaired transient response of the downsized engine. Electric Turbocharger Assist (ETA) technology integrates an electric motor/generator with the turbocharger to provide electrical power to assist compressor work or to electrically recover excess turbine power. Additionally, a variable geometry turbine (VGT) is able to bring an extra degree of freedom for the boost system optimization. The electrically-assisted turbocharger, coupled with VGT, provides an illuminating opportunity to increase the diesel engine power density and enhance the downsized engine transient response. This paper assesses the potential benefits of the electrically-assisted turbocharger with VGT to enable heavy-duty diesel engine downsizing.

Coolant formulations based on organic acid corrosion inhibitor technology have been tested in over 180 heavy duty engines for a total of more than 50 million kilometers. This testing has been used to document long life coolant performance in various engine types from four major engine manufacturers. Inspections of engines using organic acid based coolant (with no supplemental coolant additive) for up to 610,000 kilometers showed excellent protection of metal engine components. Improved protection was observed against cylinder liner, water pump, and aluminum spacer deck corrosion. In addition, data accumulated from this testing were used to develop depletion rate curves for long life coolant corrosion inhibitors, including tolyltriazole and nitrite. Nitrite was observed to deplete less rapidly in long life coolants than in conventional formulations.

Strict NOx and soot emission regulations for Diesel engines have created an interest in low-temperature partially-homogeneous combustion regimes in both the US and Europe. One strategy, Homogeneous-Charge Late-Injection (HCLI) combustion utilizes 55% or more cooled external Exhaust Gas Recirculation (EGR) with a single Direct Injection strategy to control ignition timing. These engines are operated at low temperatures to ensure near zero NOx emissions, implying that fuel in the thermal boundary layers will not reach sufficient temperature to fully oxidize, resulting in Unburnt Hydrocarbon (UHC) and CO emissions. Of particular interest to HCLI engines are the UHC's that are not fully oxidized by the Diesel Oxidation Catalyst (DOC). Experimental measurements reveal that at average equivalence ratios greater than 0.8, methane is the single largest tailpipe-out UHC emission.