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Roots blower is a rotary positive displacement pump which operates by pumping a fluid with a pair of meshing lobes. Recent trends in automotive industry demands high power density solutions for various applications. In comparison with legacy applications, compressors for high power density applications demand continuous operation with harsher duty cycle as well as demand higher pressure ratios. Because of longer duty cycles, it will be subjected to high heat loads which will cause a rise in temperatures of timing gears, bearings, and other components within the assembly. Accurate prediction of thermal performance is critical to design a durable and efficient roots blower for high power density applications. Thermal analysis of an assembly of roots blower involves modelling of multi-physics phenomena. This paper details a coupled CFD analysis approach to predict temperatures of roots blower components and timing gear case oil. Timing gears are lubricated using wet sump lubrication.

Commercial vehicles require fast aftertreatment heat-up to move the SCR catalyst into the most efficient temperature range to meet upcoming NOX regulations while minimizing CO2. The focus of this paper is to identify the technology levers when used independently and also together for the purpose of NOX and CO2 reduction toward achieving 2027 emissions levels while remaining CO2 neutral or better. A series of independent levers including cylinder deactivation, LO-SCR, electric aftertreatment heating and fuel burner technologies were explored. All fell short for meeting the 2027 CARB transient emission targets when used independently. However, the combinations of two of these levers were shown to approach the goal of transient emissions with one configuration meeting the requirement. Finally, the combination of three independent levers were shown to achieve 40% margin for meeting 2027 transient NOx emissions while remaining CO2 neutral.

Commercial vehicles require fast aftertreatment heat-up in order to move the SCR catalyst into the most efficient temperature range to meet upcoming NOX regulations. Today’s diesel aftertreatment systems require on the order of 10 minutes to heat up during a cold FTP cycle. The focus of this paper is to heat up the aftertreatment system as quickly as possible during cold starts and maintain a high temperature during low load, while minimizing fuel consumption. A system solution is demonstrated using a heavy-duty diesel engine with an end-of-life aged aftertreatment system targeted for 2027 emission levels using various levels of controls. The baseline layer of controls includes cylinder deactivation to raise the exhaust temperature more than 100° C in combination with elevated idle speed to increase the mass flowrate through the aftertreatment system. The combination yields higher exhaust enthalpy through the aftertreatment system.

Diesel Cylinder Deactivation (CDA) has been shown in previous work to increase exhaust temperatures, improve fuel efficiency, and reduce engine-out NOx for engine loads up to 3 bar BMEP. The purpose of this study is to determine whether or not the turbocharger needs to be altered when implementing CDA on a diesel engine. This study investigates the effect of CDA on exhaust temperature, fuel efficiency, and turbocharger performance in a 15L heavy-duty diesel engine under low-load (0-3 bar BMEP) steady-state operating conditions. Two calibration strategies were evaluated. First, a “stay-hot” thermal management strategy in which CDA was used to increase exhaust temperature and reduce fuel consumption. Next, a “get-hot” strategy where CDA and elevated idle speed was used to increase exhaust temperature and exhaust enthalpy for rapid aftertreatment warm-up.

Engine braking is a supplemental retarding technology in addition to foundational friction brakes in commercial vehicles. This technology is in use in Europe & Americas for several decades now. In engine braking, the engine acts as a compressor, thus producing the required braking power. The braking power is generated by either reducing the volumetric efficiency or increasing the pressure difference across the cylinder. This is usually achieved by means of exhaust valve lift modulation. There are dominantly two types of engine brakes viz. bleeder brake and compression release brake. The present work uses GT-Power® model to study the braking performance of a 4-cylinder, medium duty diesel engine at different engine RPMs and valve lifts. The work brings out a comprehensive understanding of different lift events and their effects on braking performance.

Diesel engine cylinder deactivation (CDA) can be used to reduce petroleum consumption and greenhouse gas (GHG) emissions of the global freight transportation system. Heavy duty trucks require complex exhaust aftertreatment (A/T) in order to meet stringent emission regulations. Efficient reduction of engine-out emissions require a certain A/T system temperature range, which is achieved by thermal management via control of engine exhaust flow and temperature. Fuel efficient thermal management is a significant challenge, particularly during cold start, extended idle, urban driving, and vehicle operation in cold ambient conditions. CDA results in airflow reductions at low loads. Airflow reductions generally result in higher exhaust gas temperatures and lower exhaust flow rates, which are beneficial for maintaining already elevated component temperatures. Airflow reductions also reduce pumping work, which improves fuel efficiency.

The demand for improving fuel economy in passenger cars is continuously increasing. Eliminating energy losses within the engine is one method of achieving fuel economy improvement. Frictional energy losses account for a noticeable portion of the overall efficiency of an engine. Valvetrain friction, specifically at the camshaft interface, is one area where potential for friction reduction is evident. Several factors can impact the friction at the camshaft interface. Some examples include: camshaft lobe profile, rocker arm interface geometry, valve spring properties, material properties, oil temperature, and oil pressure. This paper discusses the results of a series of tests that experimented the changes in friction that take place as these factors are altered. The impact of varying testing conditions such as oil pressure and oil temperature was evaluated throughout the duration of the testing and described herein.

Variable valve actuation is a focus to improve fuel efficiency for passenger car engines. Various means to implement early and late intake valve closing (E/LIVC) at lower load operating conditions is investigated. The study uses GT Power to simulate on E/LIVC on a 2.5 L gasoline engine, in-line four cylinder, four valve per cylinder engine to evaluate different ways to achieve Atkinson cycle performance. EIVC and LIVC are proven methods to reduce the compression-to-expansion ratio of the engine at part load and medium load operation. Among the LIVC strategies, two non-traditional intake valve lift profiles are investigated to understand their impact on reduction of fuel consumption at low engine loads. Both the non-traditional lift profiles retain the same maximum lift as a normal intake valve profile (Otto-cycle) unlike a traditional LIVC profile (Atkinson cycle) which needs higher maximum lift.

Commercial vehicles require continual improvements in order to meet fuel emission standards, improve diesel aftertreatment system performance and optimize vehicle fuel economy. Aftertreatment systems, used to remove engine NOx, are temperature dependent. Variable valve actuation in the form of cylinder deactivation (CDA) has been shown to manage exhaust temperatures to the aftertreatment system during low load operation (i.e., under 3-4 bar BMEP). During cylinder deactivation mode, a diesel engine can have higher vibration levels when compared to normal six cylinder operation. The viability of CDA needs to be implemented in a way to manage noise, vibration and harshness (NVH) within acceptable ranges for today’s commercial vehicles and drivelines. A heavy duty diesel engine (inline 6 cylinder) was instrumented to collect vibration data in a dynamometer test cell.

Increased demands for reduction of fuel consumption and CO2 emissions are driven by the global warming. To meet these challenges with respect to the passenger car segment the strategy of utilizing IC-engine downsizing has shown to be effective. In order to additionally meet requirements for high power and torque output supercharging is required. This can be realized using e.g. turbo-chargers, roots blowers or a combination of several such devices for the highest specific power segment. Both turbo-chargers and roots blowers can be strong sources of sound depending on the operating conditions and extensive NVH abatements such as resonators and encapsulation might be required to achieve superior vehicle NVH. For an efficient resonator tuning process in-duct acoustic source data is required. No published studies exists that describe how the gas exchange process for roots blowers can be described by acoustic sources in the frequency domain.

The strong focus on reducing brake drag, driven by a historic ramp-up in global fuel economy and carbon emissions standards, has led to renewed research on brake caliper drag behaviors and how to measure them. However, with the increased knowledge of the range of drag behaviors that a caliper can exhibit comes a particularly vexing problem - how should this complex range of behaviors be represented in the overall road load of the vehicle? What conditions are encountered during coastdown and fuel economy testing, and how should brake drag be measured and represented in these conditions? With the Environmental Protection Agency (amongst other regulating agencies around the world) conducting audit testing, and the requirement that published road load values be repeatable within a specified range during these audits, the importance of answering these questions accurately is elevated. This paper studies these questions, and even offers methodology for addressing them.

Light weight structures give significant advantages to products in the Industrial sector. Component weight-saving plays a major role in improving the efficiency and performance of assembled systems. The introduction of lighter materials into products using dissimilar material joining techniques can create more weight savings and leads to lighter structures. Structural optimization is another method to optimize the material layout without affecting overall performance of the product. This paper discusses the methods to create lighter structures by the introduction of lighter materials in structures and structural optimization methods. Lighter materials are introduced in the structure using dissimilar material joining techniques. Joining processes such as thermal shrink-fit and mechanical press-fit are useful for metal to metal components. Similarly, adhesively bonded joints are useful for both metal and non-metal (plastics and composites) components.

In amorphous solids such as fused quartz, the failure mechanism under cyclic loading is very different when compared to metals where this failure is attributable to dislocation movement and eventual slip band activity. Standard mechanical fatigue prediction methodologies, S-N or ε-N based, which have been historically developed for metals are rendered inapplicable for this class of material. The fatigue strength of Fused Silica or Fused Quartz (SiO2) material is known to be highly dependent on the stressed area and the surface finish. Stable crack growth in Region II of the V-K curve (Crack growth rate vs Stress intensity factor) is dependent on the competing and transitional effects of temperature and humidity, along that specific section of the stress intensity factor abscissa. Fused glass (under harsh environment conditions) finds usage in Automotive, Marine and Aerospace applications, where stress and load (both static and cyclic) can be severe.

Fuel economy is one of the major challenges for both on and off-road vehicles. Inefficient engine operation and loss of kinetic energy in the form of heat during braking are two of the major sources of wasted fuel energy. Rising energy costs, stringent emission norms and increased environmental awareness demand efficient drivetrain designs for the next generation of vehicles. This paper analyzes three different types of powertrain concepts for efficient operation of a forklift truck. Starting from a conventional torque convertor transmission, hydrostatic transmission and a hydraulic hybrid transmission (Eaton architecture) are compared for their fuel economy performance. Eaton hydraulic hybrid system is seen to perform much better compared to other two architectures. Improved fuel economy is attributed to efficient engine operation and regeneration of vehicle kinetic energy during braking.

The human thermal comfort, which has been a subject of extensive research, is a principal objective of the automotive climate control system. Applying the results of research studies to the practical problems require quantitative information of the thermal environment in the passenger compartment of a vehicle. The exposure to solar radiation is known to alter the thermal environment in the passenger compartment. A photovoltaic-cell based sensor is commonly used in the automotive climate control system to measure the solar radiation exposure of the passenger compartment of a vehicle. The erroneous information from a sensor however can cause thermal discomfort to the occupants. The erroneous measurement can be due to physical or environmental parameters. Shading of a solar sensor due to the opaque vehicle body elements is one such environmental parameter that is known to give incorrect measurement.

The vehicle air-conditioning system has significant impact on fuel economy and range of electric vehicles. Improving the fuel economy of vehicles therefore demand for energy efficient climate control systems. Also the emissions regulations motivate the reduced use of fuel for vehicle's cabin climate control. Solar heat gain of the passenger compartment by greenhouse effect is generally treated as the peak thermal load of the climate control system. Although the use of advanced glazing is considered first to reduce solar heat gain other means such as ventilation of parked car and recirculation of cabin air also have impetus for reducing the climate control loads.

In addition to the thermal comfort of the vehicle occupants, their safety by ensuring adequate visibility is an objective of the automotive climate control system. An integrated dew point and glass temperature sensor is widely used among several other technologies to detect risk of fog formation on the cabin side (or inner) surface of the windshield. The erroneous information from a sensor such as the measurement lag can cause imperfect visibility due to the delayed response of the climate control system. Also the high value, low cost vehicles may not have this sensor due to its high cost. A differential equation based model of the cabin air humidity is proposed to calculate in real-time specific humidity of the passenger compartment air. The specific humidity is used along with the windshield surface temperature to determine relative humidity of air and therefore, the risk of fog formation on the interior surface of a windshield.

Global environmental and economic concerns regarding increasing fuel consumption and greenhouse gas emission are driving changes to legislative regulations and consumer demand. As regulations become more stringent, advanced engine technologies must be developed and implemented to realize desired benefits. Discrete variable valve lift technology is a targeted means to achieve improved fuel economy in gasoline engines. By limiting intake air flow with an engine valve, as opposed to standard throttling, road-load pumping losses are reduced resulting in improved fuel economy. This paper focuses on the design and development of a switching roller finger follower system which enables two mode discrete variable valve lift on end pivot roller finger follower valvetrains. The system configuration presented includes a four-cylinder passenger car engine with an electro-hydraulic oil control valve, dual feed hydraulic lash adjuster, and switching roller finger follower.

The effects of downspeeding and supercharging a passenger car diesel engine were studied through laboratory investigation and vehicle simulation. Changes in the engine operating range, transmission gearing, and shift schedule resulted in improved fuel consumption relative to the baseline turbocharged vehicle while maintaining performance and drivability metrics. A shift schedule optimization technique resulted in fuel economy gains of up to 12% along with a corresponding reduction in transmission shift frequency of up to 55% relative to the baseline turbocharged configuration. First gear acceleration, top gear passing, and 0-60 mph acceleration of the baseline turbocharged vehicle were retained for the downsped supercharged configuration.

Diesel exhaust aftertreatment systems are required for meeting Final Tier 4 emission regulations. This paper addresses an aftertreatment system designed to meet the Final Tier 4 emission standards for nonroad vehicle markets. The aftertreatment system consists of a fuel dosing system, mixing elements, fuel vaporizer, fuel reformer, lean NOx trap (LNT), diesel particulate filter (DPF), and an optional selective catalytic reduction (SCR) catalyst. Aftertreatment system performance, both with and without the SCR, was characterized in an engine dynamometer test cell, using a 4.5 liter, pre-production diesel engine. The engine out NOx nominally ranged between 1.6 and 2.0 g/kW-hr while all operating modes ranged between 1.2 and 2.8 g/kW-hr. The engine out particulate matter was calibrated to approximately 0.1 g/kW-hr for various power ratings. Three engine power ratings of 104 kW, 85 kW and 78 kW were evaluated.