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Two-stroke engine keep-clean data is presented to demonstrate the deposit removal capabilities of a premium fuel additive. In this testing, the fuel additive was added as a top-treatment to a 50:1 blended fuel-oil mixture. Engine testing was conducted on an EchoTM SRM-265 (25.4 cc) string trimmer run under a standardized test cycle. Test measurements included piston deposits, ring deposits, and exhaust port blockage. In addition, a more complete data set was analyzed and several variables were investigated including: different base gasoline fuels, ethanol level (E0 and E10), additive dose (none, low, and high), and fuel stabilizer dose (none and high). Post-test inspection of engine parts using fuel additives showed a high level of clean surfaces, which maintained the engine at its original performance.

The torsional natural frequencies of axles equipped with limited slip differential clutches depend on whether or not the tires and clutches are slipping since the effective inertia at each end of the axle is different for slipping and non-slipping conditions. Limited slip axle vibrations are typically analyzed for one tire slipping and the other not since that is the case for which the limited slip clutches are used. Vibrations often arise, however, during normal turning when both drive tires have good traction.

Light duty vehicle emission standards are getting more stringent than ever before as stipulated by US EPA Tier 2 Standards and LEV III regulations proposed by CARB. The research in this paper sponsored by US DoE is focused towards developing a Tier 2 Bin 2 Emissions compliant light duty pickup truck with class leading fuel economy targets of 22.4 mpg “City” / 34.3 mpg “Highway”. Many advanced technologies comprising both engine and after-treatment systems are essential towards accomplishing this goal. The objective of this paper would be to discuss key engine technology enablers that will help in achieving the target emission levels and fuel economy. Several enabling technologies comprising air-handling, fuel system and base engine design requirements will be discussed in this paper highlighting both experimental and analytical evaluations.

Current production heavy duty diesel engines have a brake thermal efficiency (BTE) between 43-46% [1]. In partnership with the United States Department of Energy (DOE) as part of the Supertruck 2 program, Cummins has undertaken a research program to develop a new heavy-duty diesel engine designed to deliver greater than 50% BTE without the use of waste heat recovery. A system level optimization focused on: increased compression ratio, higher injection rate, carefully matched highly efficient turbocharging, variable lube oil pump, variable cooling components, and low restriction after treatment designed to deliver 50% BTE at a target development point. This work will also illustrate the system level planning and understanding of interactions required to allow that same 50% BTE heavy duty diesel engine to be integrated with a waste heat recovery (WHR) system to deliver system level efficiency of 55% BTE at a single point.

The influence of big-end bore fretting on connecting rod fatigue fracture is investigated. A finite element model, including rod-bearing contact interaction, is developed to simulate a fatigue test rig where the connecting rod is subjected to an alternating uniaxial load. Comparison of the model results with a rod fracture from the fatigue rig shows good correlation between the fracture location and the peak ‘Ruiz’ criterion, rather than the peak tensile stress location, indicating the potential of fretting to initiate a fatigue fracture and the usefulness of the ‘Ruiz’ criterion as a measure of location and severity. The model is extended to simulate a full engine cycle using pressure loads from a bearing EHL analysis. A fretting map and a ‘Ruiz’ criterion map are developed for the full engine cycle, giving an indication of a safe ‘Ruiz’ level from an existing engine which has been in service for more than 5 years.

Since the introduction of the catalytic converter, some automobile manufacturers have questioned whether the converter is compatible with the use of the gasoline fuel additive MMT®. Concerns have generally revolved around possible interactions between combustion products of MMT® (i.e., manganese containing compounds) and catalytic converters. In particular, concern has been raised over the possibility that MMT® combustion products physically “plug” the catalyst and cause catalyst failure, where plugging refers to blockage of contiguous pores at the catalyst inlet face or within the body of the converter. In modern vehicles this could result in the illumination of the malfunction indicator light (MIL) due to storing of an on-board diagnostic (OBD) failure code pertaining to catalyst operation or failure of a vehicle inspection and maintenance (I/M) test.

In modern engine design, downsizing and reducing weight while still providing an increased amount of power has been a general trend in recent decades. Traditionally, an engine design with superior NVH performance usually comes with a heavier, thus sturdier structure. Therefore, modern engine design requires that NVH be considered in the very early design stage to avoid modifications of engine structure at the last minute, when very few changes can be made. NVH design optimization of engine components has become more practical due to the development of computer software and hardware. However, there is still a need for smarter algorithms to draw a direct relationship between the design and the radiated sound power. At the moment, techniques based on modal acoustic transfer vectors (MATVs) have gained popularity in design optimization for their good performance in sound pressure prediction.

With increasing energy prices and concerns about the environmental impact of greenhouse gas (GHG) emissions, a growing number of national governments are putting emphasis on improving the energy efficiency of the equipment employed throughout their transportation systems. Within the U.S. transportation sector, energy use in commercial vehicles has been increasing at a faster rate than that of automobiles. A 23% increase in fuel consumption for the U.S. heavy duty truck segment is expected from 2009 to 2020. The heavy duty vehicle oil consumption is projected to grow while light duty vehicle (LDV) fuel consumption will eventually experience a decrease. By 2050, the oil consumption rate by LDVs is anticipated to decrease below 2009 levels due to CAFE standards and biofuel use. In contrast, the heavy duty oil consumption rate is anticipated to double. The increasing trend in oil consumption for heavy trucks is linked to the vitality, security, and growth of the U.S. and global economies.

Changing diesel engine emission requirements for 2002 have led many diesel engine manufacturers to incorporate cooled Exhaust Gas Recirculation, EGR, as a means of reducing NOx. This has resulted in higher levels of soot being present in used oils. This paper builds on earlier work with fresh oils and describes a study of the effect of highly sooted oils on the low temperature pumpability in diesel engines. Four experimental diesel engine oils, of varying MRV TP-1 viscosities, were run in a Mack T-8 engine to obtain a soot level ranging between 6.1 and 6.6%. These sooted oils were then run in a Cummins M11 engine installed in a low temperature cell. Times to lubricate critical engine components were measured at temperatures ranging between -10 °C and -25 °C. A clear correlation was established between the MRV TP-1 viscosity of a sooted oil and the time needed to lubricate critical engine components at a given test temperature.

Production NO sensors have a strong cross-sensitivity to ammonia which limits their use for closed-loop SCR control and diagnostics since increases in sensor output can be caused by either gas component. Recently, Ammonia/NO Ratio (ANR) perturbation methods have been proposed for determining the dominant component in the post-SCR exhaust as part of the overall SCR control strategy, but these methods or the issue of sensor cross-sensitivity have not been critically evaluated or studied in their own right. In this paper the dynamic sensor direct- and cross-sensitivities are estimated from experimental FTIR data (after compensating for the dynamics of the gas sampling system) and compared to nominal values provided by the manufacturer. The ANR perturbation method and the use of different input excitations are then discussed within an analytical framework, and applied to experimental data from a large diesel engine.

The performance of an organic Rankine cycle (ORC) that recovers heat from the exhaust of a heavy-duty diesel engine was simulated. The work was an extension of a prior study that simulated the performance of an experimental ORC system developed and tested at Oak Ridge National laboratory (ORNL). The experimental data were used to set model parameters and validate the results of that simulation. For the current study the model was adapted to consider a 15 liter turbocharged engine versus the original 1.9 liter light-duty automotive turbodiesel studied by ORNL. Exhaust flow rate and temperature data for the heavy-duty engine were obtained from Southwest Research Institute (SwRI) for a range of steady-state engine speeds and loads without EGR. Because of the considerably higher exhaust gas flow rates of the heavy-duty engine, relative to the engine tested by ORNL, a different heat exchanger type was considered in order to keep exhaust pressure drop within practical bounds.

NVH development of light duty diesel engines require significant collaboration with the OEM as compared to medium duty and heavy duty diesel engines. Typically, competitive benchmark studies and customer expectations define the NVH targets at the vehicle level and are subsequently cascaded down to the powertrain level. For engine manufacturing companies like Cummins Inc., it is imperative to work closely with OEM to deliver on the NVH expectations. In certain situations, engine level NVH targets needs to be demonstrated in the OEM or 3rd party acoustic test facility for customer satisfaction or commercial purposes. Engine noise tests across different noise test facilities may introduce some variation due to differences in the acoustic test facilities, test hardware, instrumentation differences, etc. In addition, the engine itself is a major source of variation.

Previous research to understand the mechanism for piston deposit formation in the Sequence IIIG engine test has focused on characterizing the piston deposits. These studies concluded that, in addition to lubricant derived materials, Sequence IIIG piston deposits contain a significant amount of fuel-derived carbonaceous material. The presence of fuel degradation by-products in Sequence IIIG deposits shows that blow-by is a significant contributor to deposit formation. However, blow-by can either assist in the degradation of the lubricant or can simply be a source for organic material which can be incorporated into the deposits. Therefore, a series of modified Sequence IIIG engine tests were conducted to better determine the effect of blow-by on deposit formation. In these studies deposit formation on different parts of the piston assembly were examined since different parts of the piston assembly are exposed to different amounts of blow-by.

Modern light-duty trucks and SUV's are designed to be aerodynamic to increase fuel economy. Such vehicle design significantly reduces the amount of air available to cool the rear axle in rear wheel drive vehicles. Reduced cooling coupled with higher power output and additional load from trailer towing operations results in higher axle operating temperatures, especially during the early operation or “break-in” phase of axle life. Higher axle operating temperatures decrease oil viscosity resulting in reduced oil film formation ability to protect against wear and contact fatigue. High temperature also shortens the useful life of gear oils. To facilitate the development of gear oils capable of reducing axle operation temperature, we have developed a laboratory simulation test method that can closely simulate actual trailer-towing driving on Baker's grade road under maximum GVCWR of close to 6,033 kg (13,300 lbs).

A technique for rapid in situ measurement of the fuel dilution of oil in a diesel engine is presented. Fuel dilution can occur when advanced in-cylinder fuel injection techniques are employed for the purpose of producing rich exhaust for lean NOx trap catalyst regeneration. Laser-induced fluorescence (LIF) spectroscopy is used to monitor the oil in a Mercedes 1.7-liter engine operated on a dynamometer platform. A fluorescent dye suitable for use in diesel fuel and oil systems is added to the engine fuel. The LIF spectra are monitored to detect the growth of the dye signal relative to the background oil fluorescence; fuel mass concentration is quantified based on a known sample set. The technique was implemented with fiber optic probes which can be inserted at various points in the engine oil system. A low cost 532-nm laser diode was used for excitation.

A vehicle fleet of seven low-mileage gasoline direct injection (GDI) vehicles from the U.S. market were tested to determine if GDI injector deposits were present causing a loss in fuel economy (FE). The real-world vehicles were tested “as-is” from the field. The data shows that, even in a deposit control additive (DCA) mandated market that uses E10 gasoline, injector deposits can still result in up to 2.7 % loss in FE. In addition, the data shows that the level of real-world FE loss is comparable to that demonstrated in the GDI injector fouling test developed to simulate real-world dirty-up of GDI vehicle injectors.

Evaluation of the platooning legislative space suggests a limited near-term opportunity for autonomous vehicles as currently only nine states have platooning and autonomous favorable legislations. An extensive closed-loop vehicle model simulation was conducted to quantify two-truck platooning fuel economy entitlement benefits across all United States (US) interstate routes (I-xx) spanning over 40,000 miles as compared to a single truck. A simultaneous study was carried out to identify the density of Class 8 heavy-duty trucks on these interstates, using the Freight Analysis Framework (FAF) 4 database. These two studies were combined to ascertain interstates that foresee the least fuel consumption due to platooning and thus identifying states with the most platooning benefits. Identification of states with most platooning benefits provides realistic data to push for autonomous driving and platooning legislations.

After new transmission lubricants are developed there is an extensive validation program where friction durability testing is performed on multiple clutch materials. Each durability test can run for long terms and the entire validation program can take much longer terms. A well designed lubricant and friction material will deliver the necessary friction control for construction equipment to operate at optimum level. A mechanistic construct has been evaluated to calculate friction durability in clutch systems based on fluid and surface tribological properties. Fluid properties include both boundary frictional and rheological effects. Surface properties include elastic modulus, surface roughness, asperity density and asperity tip radius. Using this mechanistic construct friction durability has been predicted.

An automatic transmission planetary gear fatigue test is used to screen lubricant performance of various automatic transmission fluids. The key use of this test is to assess the ability of a lubricant to extend or limit planetary gear system fatigue life. We study the fatigue behavior in this test and find the major failure modes are tooth macropitting, and macropitting-related tooth fracture of the sun and planetary gears (short and long pinion gears). Micropitting appears to be responsible for these gear failure modes. Macropitting is also seen on the shafts and needle rollers of the bearings. Gear tooth fracture appears to have originated from the surface as a secondary failure mode following macropitting. Bearing macropitting is initiated by geometric stress concentration. Bending fatigue failure on the sun and planetary gears also occurs but it is not a micropitting-initiated failure mode.

Improving engine efficiency and reducing the total cost of ownership demands engine friction loss reduction through optimal design, especially for large bore application considering the amount of fuel the engine consumes during its service life. Power cylinder is a big source for engine friction and piston accounts for about 25% to 47% of the power cylinder friction [1]. Thus the piston design needs to be optimized to minimize friction; and at the same time, not sacrificing the durability. This work focuses on piston friction reduction by utilizing shorter compression height piston for large bore engine application through analytical simulation study. From the simulation study, 12.5% friction reduction has been achieved in the piston skirt to liner interface for the shorter piston with longer connecting-rod compared to the baseline design.