Browse Topic: Crankcases
A computational investigation was carried out using SimericsMP+ to analyze oil distribution and aeration behavior in a V6 engine oil pan during severe vehicle maneuvers. The model accounted for the crankshaft/camshaft rotations and piston motions, which allows for capturing realistic oil distribution in cylinder head drainbacks, engine bay and sump after initializing the crankcase with prescribed oil levels to establish baseline aeration prior to applying dynamic maneuver profiles. Of particular interest was the response of the main oil gallery (MOG) pressure and the exposure of the oil pickup tube during kickoff conditions at multiple fill levels. Both a baseline configuration and a modified sump featuring a containment “doghouse” were examined. Results obtained from the kickoff maneuver show complete uncovering of the pickup tube in the baseline design, leading to unstable lubrication. The first doghouse design only delayed pickup tube uncovering briefly, as oil pooled at the rear gap and air ingestion still occurred. Full fill avoids air ingestion; however, high interaction with the crank shaft results in higher oil aeration longer term after kickoff maneuver ends. The findings highlight the complexity of oil behavior in engine environments, where unpredictable interactions during dynamic maneuvers can easily lead to ingestion and aeration. Despite this complexity, the computational strategy developed in this study was able to accurately reproduce and predict these events which were seen in the test scenario as well in the form of pressure readings at the pump inlet. Since these high-aeration events were validated against experimental measurements, this simulation approach proves to be highly valuable for guiding product design and optimization, allowing engineers to identify risks early and improve lubrication performance in the engines before physical testing.
Emissions regulations, such as Euro VI, drives the Automotive industry to innovate continuously in Engine development. One significant challenge is the engine oil pumping from the crankcase into the combustion chamber, where it participates in combustion, which contributes to increased Particulate Numbers and fails to meet Euro VI emission compliance. This issue is most noticeable during engine idling and motoring conditions. During this time, a higher negative pressure difference develops between the intake manifold, which is acting above the combustion chamber and the engine crankcase. This pressure difference drives oil-laden blow-by aerosols past piston rings during the intake stroke and through the valve stem seals, allowing oil into the combustion chamber. The impact of the pressure difference between the intake manifold and crankcase was studied by varying the crankcase pressure through crankcase ventilation system. The results confirm that oil entry into the combustion chamber, contributing to combustion, occurs primarily through the piston rings, contributing to increase in Particulate Number (PN). To address this issue, it becomes necessary to introduce a mechanism that optimizes negative crankcase pressure across varying engine operating conditions. By reducing the pressure difference between the intake manifold and crankcase, this mechanism prevents oil entering the combustion chamber, thereby minimizing Particulate Number emissions and ensuring Euro VI compliance. This study focuses on the development and implementation of a negative crankcase pressure control system via the crankcase ventilation system. Through targeted optimization, it provides an effective way to control oil pumping into the combustion chamber, thereby enhancing emission control and advancing the development of cleaner Naturally Aspirated Gas engines.
This document describes methodologies to determine the causes of high oil consumption caused primarily by the power cylinder system.
Due to increasing pollution and climatic cries, newly implemented BS-VI emission norms in India have stressed the reduction of emission. For which many automobiles have been shifted to alternate fuels like CNG. Also, the Indian Automotive market is fuel economy cautious. This challenges to focus on improving fuel economy but without an increase in emissions. Crankcase blow-by gases can be an important source of particulate emission as well as other regulated and unregulated emissions. They can also contribute to the loss of lubricating oil and fouling of surface and engine components. Closed Crankcase Ventilation (CCV) or Open Crankcase Ventilation (OCV) is capable to reduce particulate emissions by removing the oil mist that is caused mainly due to blow-by in the combustion chamber. This paperwork is focused, to measure the effectiveness of the CCV and OCV systems on the engine-out emissions, primarily on the particulate emissions. A comparative analysis of these crankcase ventilation systems is made by monitoring various parameters, like engine speed, torque, crankcase pressure, engine blow-by, etc. to analyze the effectiveness of these systems for the reduction in particulate emissions.
As part of transformation from BS4 to BS6 automobile emission standard in India, engine manufactures are focusing on continuous development of emission control technologies and suitable strategies. Exhaust tail pipe emission and Crankcase emission are added together to meet the regulation acceptable limit. The crankcase emissions contribute substantially to the total Particulate Matter (PM) emitted from an engine. Hence there is a need of design and development of suitable Crankcase ventilation system. This paper presents investigation of high PM contributed from Open Crankcase ventilation (OCV) system in Diesel engine and experiment based solutions.
An afterburner-assisted turbocharged single-cylinder 425 cc two-stroke SI-engine is described in this simulation study. This engine is intended as a Backup Range Extender (REX) application for heavy-duty battery electric vehicles (BEV) when external electric charging is unavailable. The 425 cc engine is an upscaled version of a 125 cc port-injected engine [26] which demonstrated that the selected technology could provide a specific power level of 400 kW/L and the desired 150 kW in a heavy duty BEV application. The 425 cc single cylinder two-stroke engine is an existing engine as one half of a 850 cc snowmobile engine. This simulation study includes upscaling of the swept volume, impact on engine speed and gas exchange properties. In the same way as for the 125cc engine [26], the exhaust gases reaches the turbine through a tuned exhaust pipe and an afterburner or oxidation catalyst. The intent with the afterburner is to convert some of the air and hydrocarbons (HC) to heat to provide turbine power at a lower turbine pressure ratio. The turbocharger of the upscaled 425 cc engine was also linked to an electrical machine which was able to either absorb or extract power from the turbocharger shaft. This technique is sometimes referred to as super compounding. Downstream the turbine another oxidation catalyst was installed and utilized as a HC clean up catalyst. It is demonstrated that the upscaled engine obtains optimum gas exchange conditions at a lower engine speed because of the port area relationship to the swept volume. The crank case compression ratio (CCR) increases due to the upscaling which has an impact on the optimum pressure difference between the air and exhaust side to optimize the gas exchange process. The upscaled engine also operates at higher air mass rates which allows the use of larger turbocharger compressors and turbines able to operate with higher efficiencies. Higher turbocharger efficiencies also contribute to lower pressure ratios on the turbine side for any given compressor pressure ratio which improves scavenging properties. The clean-up catalyst makes it possible to oxidate all the remaining HC in the exhaust gases in certain engine speed ranges.
Power dense internal combustion engines (ICEs) are interesting candidates for onboard charging devices in different electric powertrain applications where the weight, volume and price of the energy storage components are critical. Single-cylinder naturally aspirated two-stroke spark-ignited (SI) engines are very small and power dense compared to four-stroke SI engines and the installation volume from a single cylinder two-stroke engine can become very interesting in some concepts. During charged conditions, four-stroke engines become more powerful than naturally aspirated two-stroke engines. The performance level of a two-stroke SI engines with a charging system is less well understood since only a limited number of articles have so far been published. However, if charging can be successfully applied to a two-stroke engine, it can become very power dense. This article outlines some of the challenges related to charging systems for a single-cylinder crank case scavenged two-stroke SI engine. Different charging scenarios were investigated and a charging system was selected and optimized to meet the scavenging and gas exchange needs of two-stroke engine. A 125 cc single-cylinder two-stroke engine with a turbocharger was simulated and tested successfully to a performance level of 400 kW/L.
Design and development of high-pressure pipe involves number of design validation plans for robust design in diesel engine. The fundamental behavior of two-cylinder diesel engine with parallel stroke involves high vibration which generates stress on components mounted on crankcase resulting into earlier fatigue failure. In this paper, the innovative approach of using optimized design of vibration damper for resolving high vibration stress concerns in fuel system is discussed. The vibration dampers were designed meeting both performance and durability aspects in two-cylinder diesel engine applicable for both passenger and commercial vehicle. This paper highlights the design approach involving experimental stress measurements and design optimization based on part development feasibility. We measured the vibration stress of the complete fuel system on engine test bench as well as in vehicle chassis dyno at different loads and engine speed to confirm the existence of resonance phenomenon in both conditions of with and without vibration dampers added in high pressure fuel injection pipe. Without vibration dampers, maximum vibration stress value measured was 154 MPa in fuel injection pipe exceeding design limit of 100 MPa. With the help of improved design having evaluated weight configuration of vibration dampers, the stress was reduced drastically to 52 MPa resolving the high risk of fuel system breakage. This paper also deals with validation approach to evaluate fuel system with vibration dampers in both test bed and vehicle level at different duty cycles to confirm on design validation before implementation.
Currently automotive design is facing multi facet challenges such as reduction in greenhouse gases, better thermal management, and low cost solution to market, vehicle weight management etc. Considering these challenges, efforts had been taken to improve weight management of engine while optimizing the cost of it. Good ‘engine breathing’ is usually associated with efficient intake system e.g. high flow air filter, a well-designed manifold, cylinder block, cylinder head and cylinder head cover etc. However, efficient ‘crankcase breathing’ is an equally important function of any engine. Even in a new engine, the combustion pressure will inevitably pass the piston rings into the crankcase. If an engine’s breathing system should become blocked or restricted, the crankcase will pressurize causing lots of problems to the engine. Prior to 1963 most vehicle engines vented their vapors and oil deposits to atmosphere and the road surface. With increasing environmental pressures positive crankshaft ventilation was introduced whereby the crankcase vapors were drawn up into the inlet manifold and, along with the air/fuel mixture, burned up in the combustion chambers. To enable this system to work safely and efficiently the ventilation from the crankcase is controlled via a PCV valve which can be integrated with the engine cylinder head cover. A cylinder head cover, particularly for covering a cylinder head of an internal combustion engine, having a plurality of functional elements such as an oil filling connection and at least one oil separation device mounted thereon. There are different materials can be used for cylinder head cover, but we have selected plastic material for engine weight reduction. This design change was successfully introduced on light duty diesel engine with newly featured three leap cylinder head cover gasket to ensure positive sealing of engine gases and engine lubricant.
The methods and principles of monitoring and diagnosing the parameters of power units are generalized. They allow increasing the wheeled vehicles operational reliability. Systems for monitoring the functional stability parameters of the most sensitive to operating conditions systems and assemblies of machines have been developed on the example of a cylinder-piston engine group and steering. An improved method for diagnosing the steering of an articulated wheeled vehicle, which significantly affects the safety of its use, is proposed based on the use of angular accelerations of sections in the road plane as a diagnostic parameter. The dependence for determining the angular accelerations for the case of the random installation of two sensors of the mobile registration and measuring complex on the machine, which allows increasing the accuracy of measurements, is obtained. Experimental studies to diagnose the steering of wheeled vehicles with various operating times have been carried out. It has been established that when running up to 6000 hours, the diagnostic parameter can be reduced to 15%. Theoretical and experimental studies were carried out for the cylinder-piston group, which established that the amount of gas passing through the valve mechanism of the cylinder head is proportional to wear and amounts to 5-15% for new and 25-40% for repaired engines of the total crankcase gases. Using the obtained dependences, the method for assessing the technical condition has been developed, which differs from the existing with separation of gas flows passing into the crankcase through the gaps "valve stem - guide sleeve" and "sleeve - piston". Also the control system that allows to determine the speed and quantity of gases passing through these gaps in all operating modes of new and repaired engines has been developed. The proposed system allows increasing the accuracy of assessing the technical condition of the cylinder-piston engine group by 40%.
Beside the main trend technologies such as downsizing, down speeding, external exhaust gas recirculation, and turbocharging in combination with Miller cycles, the optimization of the mechanical efficiency of gasoline engines is an important task in meeting future CO2 emission targets. Friction in the piston assembly is responsible for up to 45% of the total mechanical loss in a gasoline engine. Therefore, optimizing piston assembly friction is a valuable approach in improving the total efficiency of an internal combustion engine. The form honing process enables new specific shapes of the cylinder liner surface. These shapes, such as a conus or bottle neck, help enlarge the operating clearance between the piston assembly and the cylinder liner, which is one of the main factors influencing piston assembly friction. To evaluate the potential of form honing, with respect to the optimization of frictional loss in the piston assembly, knowledge of the tribological effects occurring during the combustion cycle is of crucial importance. For this reason, tests of several configurations, with and without form honing, are carried out in a so-called floating liner engine. The single cylinder test carrier introduced, which functions according to the floating liner principle, was developed by the Chair of Internal Combustion Engines of the Technical University of Munich. It allows the direct and crank angle-resolved measurement of the piston assembly friction forces. Based on the crank angle-resolved friction force measurements presented, the effects of the crankcase material, piston clearance, and operation mode of piston cooling on the potential benefits of the form honing are discussed in detail.
For the gasoline engine, the isochoric process is the ideal limit of the ideal processes. During the project, a combustion engine with real isochoric boundary conditions is built. A “resting time” of the piston for several degrees crank angle in the top dead center (TDC) can be realized with a special crank drive. This crank drive consists of two crankshafts with different strokes, which are combined. The two crankshafts rotate with a ratio of two to one in opposite directions. The total stroke corresponds to the amount of the first crankshaft, so it is possible to investigate different strokes of the second crankshaft in the same crankcase. Different “resting times” can be achieved by different strokes of the second crankshaft. A specific combination of both crankshafts make a stroke possible which corresponds to that of a conventional combustion engine. In addition to the standard cylinder pressure sensor, a quick surface temperature probe is also used as supplementary measurement technology. The influence of isochoric combustion is studied with constant air mass and constant lambda at three different strokes of the small crankshaft.
Aside from aerosols produced during the combustion of fossil fuels, the oil mist vented through the crankcase breather of the engine is considered as a threat to the environment or, in case of closed ventilation systems, to the functionality of the engine. In the past, these “blow-by” aerosols have been investigated mainly from the perspective of emitted oil mass. This study instead focuses on sources and reduction of fine aerosols in the size range of about 0.2-5 μm, where number concentrations are of equal importance. The investigation is conducted on a commercial truck diesel engine; aerosols are sampled with an optical particle counter at various locations along the blow-by path, in the region of the cylinder head before and after the oil aerosol separation system. The contribution of the turbocharger to the total aerosol load is found to be 24% by number and 21% by mass. The air compressor adds 8%-20% concerning number and mass only depending on the engine load. The influences of the engine load and engine speed are investigated across the engine performance map, whereby the load turns out to be more relevant. By keeping the oil temperature constant across the entire range, it also presents that the oil temperature plays an important - but not the only - role for the emission level. Based on the relatively constant shape of particle size distributions across a wide range of engine loads and speeds, one can conclude that the mechanisms of droplet generation remain largely unchanged. As expected, the passive pre-separator does not have a noticeable removal effect in the size of interest, while the active main separator removes 99% of the total mass down to 0.2 μm, and between 78% and 98% of the total number.
When the engine oil evaporates in the crankcase, it is necessary to discharge to the outside of the engine or returns to the intake air as part of blow-by gas. The amount of oil content in the blow-by gas is preferable to be as small as possible. This paper researched the evaporation characteristics of diesel engine oil for heavy duty into blow-by gas using 5W-30 and 10W-30 engine oils with the equivalent to Noack. As a result, it is found that evaporate phenomenon cannot be explained well enough by just Noack and clarified of the oil evaporation mechanism in blow-by gas.
Currently automotive industry is facing bi-fold challenge of reduction in greenhouse gases emissions as well as low operating cost. On one hand Emission regulations are getting more and more stringent on other hand there is major focus on customer value proposition. In engine emission the blow by gases are one of the source of greenhouse gases from engine. Blow-by gases not only consist of unburnt hydrocarbons but also carry large amount of oil. If oil is not separated from these gases, it will led to major oil consumption and hence increase total operating cost of Vehicle. Considering the above challenges, effort taken to develop a low-cost closed crankcase ventilation with oil mist separation system on diesel engine. For cost-effective solution, two different design and configuration of oil mist separation system developed. Further, engine with two different above said configuration has been tested for blow-by gasses and oil consumption measurement on Engine test bed and vehicle to understand the behavior in real environment. Further results compared for both configuration and further actions proposed.
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