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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.

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.

Reports of disabling diesel engine seal failures which accompanied the introduction of low sulfur diesel fuel in October '93 prompted an in-depth survey of diesel fuel chemical and physical properties. The purpose of the survey was to anticipate other possible problems which might arise with the newly introduced low sulfur fuels. The survey will produce a database containing over 1000 number 2 diesel fuels from various parts of the US. About 75% of the samples tested were on-highway low sulfur diesel fuels. Samples analyzed were from the D-A Lubricant Company, Cummins customers failures (truck fleets of various sizes), and a number of retail fueling stations. Properties under investigation are % Sulfur, Cloud/Pour Points, Viscosity, API Gravity, TAN/TBN, Boiling Range, Aromatics content, Heat Content, Lubricity, and Peroxide number.

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 entire engine lubrication system has been represented by a series-parallel network of flow passages and flow elements. The pressure distribution and flow rates in the network were computed according to pressure-flow characteristics of each element. The pressure-flow relationship for each network element was estimated using empirical pipe friction, expansion, and bend loss coefficients, as well as by using test rig results and a steady-state journal bearing model. The journal bearing model is basically that of the classical short bearing model with provision for heat transfer to the oil and the relative thermal growth of the journal and bearing system. When compared with diesel engine tests, the simulation predicted the pressure distribution throughout the engine and the flow rate through each branch within 10%.

The ongoing need for improved fuel economy, longer engine life, lower emissions, and in some cases, increased power output makes lower charge air temperatures more desirable. In 1983, Cummins introduced the new BCIV engine at 400 H.P. (298 KW) with “Optimized Aftercooling”, and is now introducing this concept to its remaining 10 and 14 Litre premium diesel engines. This Tuned Low Flow Cooling design provides many advantages when compared to the other alternatives studied, which included air-to-air and systems incorporating two radiators. The selection process considered performance, durability, fuel economy, emissions, noise, investment, and total vehicle installed cost. Computer simulations and vehicle tests were used to determine performance for each charge air cooling alternative. The simulations were used to guide prototype development and the selection of production hardware.

Laboratory tests have shown that 40% glass-reinforced PPS is suitable for automotive underhood use where it comes into contact with used engine oil, gasoline/alcohol, gasoline/MTBE, water, water/ethylene glycol, hydraulic fluid, and transmission fluid at elevated temperatures. On exposure to water or water/ethylene glycol at 248° F (120° C) and 257°F (125°C), respectively, there is a sharp decline in mechanical strength in the first few weeks with little change thereafter. The residual strength of the 40% glass-reinforced PPS is comparable to, or better than other materials, such as phenolics, which have proved satisfactory in such usage. These results have been translated to successful applications in heavy duty diesel engines. Piston cooling nozzles and water pump impellers made of 40% glass-reinforced PPS have undergone successful engine component evaluations.

The ability of a piston oil ring to conform to liner distortions during engine operation is directly related to its radial stiffness. The ability to conform is also very important for controlling lubricant oil consumption and emissions. This paper describes the procedure utilized to investigate the technical feasibility of using flexible high performance engineering plastics to replace metal as base material for oil rings. Bench tests and engines were used to select and evaluate different types of plastics for wear resistance and structural integrity. Engine test results indicated no structural failures but wear levels were found to be unacceptably high for use in durable heavy duty diesel engines.

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.

The modified hypocycloid (MH) mechanism, which uses gears to produce straight line motion, has been proposed as an alternative to the slider-crank mechanism for internal combustion (IC) engines. Advantages of the MH mechanism over the slider-crank for an IC engine include the capability of perfect balancing with any number of cylinders and the absence of piston side loads. The elimination of piston side load has the potential for lower piston friction, reduced piston slap, and less susceptibility to cylinder liner cavitation. To evaluate the concept, an experimental single cylinder four-stroke engine which utilizes the MH mechanism is currently being built at the University of Wisconsin-Madison. The MH engine has an increased number of friction interfaces compared to a conventional slider-crank engine due to additional bearings and the gear meshes. Thus, the lubrication of these components is an important issue in total MH engine friction.

A high horsepower, low heat rejection diesel engine is being developed to meet future Army heavy combat vehicle requirements. This engine features high power output in a compact design that is oil-cooled allowing for a significant reduction in radiator size. This design requires a lubricant which can survive a sump temperature of 160°C, for 300 hours with transient sump temperature surges to over 177°C. A comprehensive high temperature lubricant development program has been initiated to address the need for this new design. A modified Cummins 10 liter diesel engine was used to simulate the operating condition of this low heat rejection engine. The premium commercial lubricant that was tested survived only 58 hours before completely losing oxidative stability. Several of the experimental lubricants completed the 200-hour peak torque endurance test.

Transient operation of automobile engines is known to contribute significantly to regulated exhaust emissions, and is also an area of drivability concerns. Furthermore, many on-board diagnostic algorithms do not perform well during transient operation and are often temporarily disabled to avoid problems. The inability to quickly and repeatedly test engines during transient conditions in a laboratory setting limits researchers and development engineers ability to produce more effective and robust algorithms to lower vehicle emissions. To meet this need, members of the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin-Madison have developed a high-bandwidth, hydrostatic dynamometer system that will enable researchers to explore transient characteristics of engines and powertrains in the laboratory.

Caterpillar Inc. has developed a new diesel engine fuel system, powered by hydraulics and controlled electronically. This Hydraulic Electronic Unit Injector, (HEUI), requires no mechanical actuating or mechanical control devices, and offers many advantages over conventional fuel injection systems. Inherent features of the HEUI Fuel System include injection pressure control independent of engine load or speed, totally flexible injection timing, and full electronic control of injection parameters. Packaging the HEUI Fuel System on an engine is simple, as the injector is compact and available in a variety of configurations. The hydraulic actuating circuit is straightforward, using lubricating oil from the engine sump. Hydraulic lines may be internal to the engine or external. This paper describes the Caterpillar HEUI Fuel System, its operating features, performance advantages, and application to diesel engines.

Lubricating oil affects the performance of friction materials in transmission, steering and brake systems. The TO-2 Test measured friction retention characteristics of lubricating oils used with sintered bronze friction discs. This paper introduces a new friction performance test for drive train lubricants that will be used to support Caterpillar's new transmission and drive train fluid requirements, TO-4, which measures static and dynamic friction, wear, and energy capacity for six friction materials, and replaces the TO-2 test. The new test device to be introduced is an oil cooled, single-faced clutch in the Link Engineering Co. M1158 Oil/Friction Test Machine.

Field testing of an extended life coolant technology in Class 8 trucks, equipped with Caterpillar C-12 engines revealed excellent coolant life with negligible inhibitor depletion to 400,000 miles with no refortification and no coolant top-off. In separate evaluations in Caterpillar 3406E equipped trucks, extended corrosion protection and component durability were established out to 700,000 miles, without the need for refortification other than top-off.

Increasingly, the exchanges of data in complex ECM (Electronic Control Module) systems rely on multiple communication networks across various physical and network layers. This has greatly increased system flexibility and provided an excellent medium to create well-defined exchangeable interfaces between components; however this added flexibility comes with increased network complexity. A system-level approach allows for the optimization of data exchange and network configuration as well as the development of a comprehensive network failure strategy. Many current ECM systems utilize complex multi-network communication strategies to exchange and control data to components. Recently, Caterpillar implemented an HIL (Hardware-In-the-Loop) test system that provides an approach for developing and testing a comprehensive ECM network strategy.

The effect of piston ring pack crevice flow and lubricant oil vaporization on heavy-duty diesel engine deposits is investigated numerically using a multidimensional CFD code, KIVA3V, coupled with Chemkin II, and computational grids that resolve part of the crevice region appropriately. Improvements have been made to the code to be able to deal with the complex geometry of the ring pack, and sub-models for the crevice flow dynamics, lubricating oil vaporization and combustion, soot formation and deposition were also added to the code. Eight parametric cases were simulated under reacting conditions using detailed chemical kinetics to determine the effects of variations of lube-oil film thickness, distribution of the oil film thickness, number of injection pulses, and the main injection timing on engine soot deposition. The results show that crevice-borne hydrocarbon species play an important role in deposit formation on crevice surfaces.

The specific goal of this project was to determine if there is a difference in the lube oil degradation rates in a heavy-duty diesel engine equipped with an EGR system, as compared to the same configuration of the engine, but minus the EGR system. A secondary goal was to develop FTIR analysis of used lube oil as a sensitive technique for rapid evaluation of the degradation properties of lubricants. The test engine selected for this work was a Caterpillar 3176 engine. Two engine configurations were used, a standard 1994 design and a 1994 configuration with EGR designed to meet the 2004 emissions standards. The most significant changes in the lubricant occurred during the first 50-100 hours of operation. The results clearly demonstrated that the use of EGR has a significant impact on the degradation of the engine lubricant.

Testing of ducted fuel injection (DFI) in a single-cylinder engine with production-like hardware previously showed that adding a duct structure increased soot emissions at the full load, rated speed operating point [1]. The authors hypothesized that the DFI flame, which travels faster than a conventional diesel combustion (CDC) flame, and has a shorter distance to travel, was being re-entrained into the on-going fuel injection around the lift-off length (LOL), thus reducing air entrainment into the on-going injection. The engine operating condition and the engine combustion chamber geometry were duplicated in a constant pressure vessel. The experimental setup used a 3D piston section combined with a glass fire deck allowing for a comparison between a CDC flame and a DFI flame via high-speed imaging. CH* imaging of the 3D piston profile view clearly confirmed the re-entrainment hypothesis presented in the previous engine work.

Corrosive wear of non-ferrous engine components by lubricants is a concern of all major heavy duty diesel engine manufacturers since warranty on key engine components has been extended to 500,000 miles. Several commercial lubricants have been linked to premature cam and rod bearing failures induced by corrosion in certain fleets. Although the overall failure rate is low, specific fleets have experienced significantly higher failure rates due to the lubricants used. These failures usually occur at high mileages but less than 500,000 miles. This kind of slow corrosion easily escapes detection of engine tests contained in current oil specifications, and it represents a serious issue in long term warranty cost to diesel engine manufacturers. A comprehensive fleet database has been established to identify the most corrosive lubricants. These lubricants have served as reference oils to develop a corrosion bench test.