| 1. |
- Falck, Annki, et al.
(författare)
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Early risk identification and cost-benefit analyses through ergonomics simulation
- 2009
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Ingår i: Digital Human Modeling for Design and Engineering Conference and Exhibition, DHM 2009; Gothenburg; Sweden; 9 June 2009 through 9 June 2009. - 400 Commonwealth Drive, Warrendale, PA, United States : Society of Automotive Engineers. ; , s. 10-
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Konferensbidrag (refereegranskat)abstract
- For cost-beneficial reasons simulations with computer manikins have been increasingly used in the automotive industry for prediction of ergonomics problems before the product and work place exist in physical form. The main purpose of ergonomics simulations is to apply biomechanical models and data to assess the acceptability of the physical work load, e.g., working postures, visibility, clearance, etc., which could result in requirements to change the design of the product. The aim is to improve ergonomics conditions in manual assembly and to promote a better product quality through improved assemblability (ease of assembly). Many studies have shown a clear correlation between assembly ergonomics and product quality and that poor assembly ergonomics result in impaired product quality and in decreased productivity. Nevertheless, there are remaining difficulties in achieving acceptance for changes of product and production solutions because of poor assembly ergonomics.A recent study in the Swedish automotive industry showed that huge savings and increased profit margins can be obtained by eliminating ergonomics risk concepts in the very early product development process. The study confirmed a strong relation between poor ergonomics assembly solutions and quality errors of the product (car). There was a substantially increased risk for quality errors and increased costs for corrective measures of the product for assembly items of high and moderate physical work load compared to assembly items of low work load. The quality risk was increased 3 and 3.7 times, respectively. The overall cost for corrective measures in the assembly plant and for factory complete cars was 8.7 and 8.2 times higher for assembly items of high and medium physical work load compared to items of low physical work load.The purpose of this paper is to demonstrate the need for ergonomics simulations of potentially harmful assembly concepts in combination with cost-benefit analyses of conceivable system solutions based on calculation of costs for quality errors related to poor ergonomics and poor assemblability. The intended end result of this research is a model by application of which it is possible to calculate the cost for quality losses and health effects due to poor ergonomics and compare it with the cost for improving the ergonomics with designers, manufacturing engineers and ergonomists as main users.
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| 2. |
- Eidevåg, Tobias, 1987, et al.
(författare)
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Snow Contamination of Simplified Automotive Bluff Bodies: A Comparison between Wind Tunnel Experiments and Numerical Modeling
- 2022
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Ingår i: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 2641-9637 .- 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- We describe experiments and numerical modeling of snow surface contamination on two simplified automotive bluff bodies: The Ahmed body and a wedge. The purpose was twofold: 1) To obtain well defined experimental results of snow contamination on simple geometries; 2) To propose a numerical modeling approach for snow contamination. The experiments were performed in a climatic wind tunnel using a snow cannon at −15 °C and the results show that the snow accumulation depends on the aerodynamics of the studied bluff bodies. Snow accumulates on surfaces in proximity to the aerodynamic wakes of the bodies and characteristic snow patterns are obtained on side surfaces. The numerical modeling approach consisted of an aerodynamic setup coupled with Lagrangian particle tracking. Particles were determined to adhere or rebound depending on an adhesion model combined with a resuspension criterion. The adhesion model was based on adhesive-elastic contact theory and the resuspension criterion is derived from the balance between the aerodynamic forces acting on a particle and the critical force for onset of resuspension. The results show that the numerical method can predict certain characteristic snow patterns obtained from the experiments and we also highlight deviations obtained between experimental and simulation results. The simulation results show that the snow accumulation patterns on a bluff body will depend on the smallest ice particles in a snow sample which implies that samples with larger ice particle (for example natural snow) could produce different snow patterns than the fine machine-made snow used in this study.
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| 3. |
- Persson, Erik, et al.
(författare)
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Clamp Force Accuracy in Threaded Fastener Joints Using Different Torque Control Tightening Strategies
- 2021
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Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; :2021
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Tidskriftsartikel (refereegranskat)abstract
- The assembly of threaded fasteners may seem straightforward. However, there are many factors to consider to achieve quality tightened joints, including the joint material, threaded fastener, and coatings. Additionally, there are many assembly tool types and torque application strategies to choose from. This investigation studies the tightening speed dynamics when using torque as a control method. The clamp force obtained in the joint changes when tightening at high speed or when the speed varies greatly during tightening. This type of tightening is called highly dynamic. Highly dynamic torque control tightening strategies are studied, such as impact, pulse, and inertia-controlled methods, and compared with the continuous drive strategy, which is a standard dynamic torque tightening method. The clamp force and its scatter caused by the torque accuracy in the assembly tool type are investigated for the abovementioned torque application strategies. The study also focuses on the different results obtained from the International Organization for Standardization’s (ISO) 16047:2005 (Fasteners-Torque/clamp force testing) standard compared to a production-like setup.
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| 4. |
- Adlercreutz, Ludvig, et al.
(författare)
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Optimizing the Natural Gas Engine for CO2 reduction
- 2016
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- With alternative fuels having moved more into market in light of their reduction of emissions of CO2 and other air pollutants, the spark ignited internal combustion engine design has only been affected to small extent. The development of combustion engines running on natural gas or Biogas have been focused to maintain driveability on gasoline, creating a multi fuel platform which does not fully utilise the alternative fuels' potential. However, optimising these concepts on a fundamental level for gas operation shows a great potential to increase the level of utilisation and effectiveness of the engine and thereby meeting the emissions legislation. The project described in this paper has focused on optimising a combustion concept for CNG combustion on a single cylinder research engine. The ICE's efficiency at full load and the fuels characteristics, including its knock resistance, is of primary interest - together with part load performance and overall fuel consumption. In the process of increasing the efficiency of the engine the following areas have been of primary interest, increased compression ratio, thermal load at high cylinder pressure and the use of EGR to further increase efficiency. The overall goal in the project was to reduce the CO2-emissions while maintaining the performance and characteristics of the engine. The ambition is to reduce specific tail-pipe CO2-emissions in g/kWh by 50% compared to a modern gasoline engine. The goal was close to being reached at 45% reduction at full load and 25-34% on part load. This was done by theoretically downsizing the engine and increasing the specific performance of the engine.
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| 5. |
- Adlercreutz, Ludvig, et al.
(författare)
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Particle Emission Measurements in a SI CNG EngineUsing Oils with Controlled Ash Content
- 2019
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Clean combustion is one of the inherent benefits of using a high methane content fuel, natural gas or biogas. A single carbon atom in the fuel molecule results, to a large extent, in particle-free combustion. This is due to the high energy required for binding multiple carbon atoms together during the combustion process, required to form soot particles. When scaling up this process and applying it in the internal combustion engine, the resulting emissions from the engine have not been observed to be as particle free as the theory on methane combustion indicates. These particles stem from the combustion of engine oil and its ash content. One common practice has been to lower the ash content to regulate the particulate emissions, as was done for diesel engines. For a gas engine, this approach has been difficult to apply, as the piston and valvetrain lubrication becomes insufficient. However, the low particle emissions from the combustion of CNG does allow for an investigation of particle contribution from engine oil ash content with only a minor particle contribution from the fuel itself. The hypothesis for this study is that there is a relationship between the engine oil ash content and the particulate emissions from a CNG engine. The investigation was conducted for several operating points with varying engine speeds and load on a single cylinder engine. The single cylinder approach was chosen to reduce sources of engine oil intrusion in the combustion chamber. The obtained results were not in line with the hypothesis, the particle emissions from the lower ash content oil did not decrease in number but the size of the particles did. The results also showed a spiking behavior in the particulate emissions, originating from the lubrication oil consumption past the piston rings. Mass flow through the engine proved to affect the particle size distribution as well as the total number of particles for all levels of oil ash content.
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| 6. |
- Adlercreutz, Ludvig, et al.
(författare)
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Variation in Squish Length and Swirl to Reach Higher Levels of EGRin a CNG Engine
- 2019
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Ingår i: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Gaseous methane fuel for internal combustion engineshave proved to be a competitive source of propulsionenergy for heavy duty truck engines. Using biogascan even reduce the carbon footprint of the truck to near-zerolevels, creating fully environmentally friendly transport. Gasengines have already been on the market and proved to be apopular alternative for buses and waste transport. However,for long haulage these gas engines have not been on par withthe equivalent diesel engines. To improve the power and efficiencyof EURO VI gas engines running stoichiometrically, adirect way forward is adding more boost pressure and sparkadvance in combination with more EGR to mitigate knock.Using in-cylinder turbulence to achieve higher mixing rate,the fuel can still be combusted efficiently despite the increasedfraction of inert gases. In this paper, previous findings onin-cylinder air flows for diesel engine simulations are investigatedfor the applicability on to stoichiometric gas combustion.Two key parameters were identified, swirl and squish.By varying the levels of swirl with different squish lengths inthe piston design, the in-cylinder flow motion is altered toinvestigate its effect on stoichiometric gas combustion. Thetesting was performed on a single cylinder research engineoperated in the equivalent multi cylinder engine operatingpoints. The results show that previous modelling findings areverified on the pre-mixed gas combustion studied. By choosingswirl and squish for the design of the gas engine, it is possibleto increase the combustion speed and thus the fraction of EGRin the combustion charge, without the latter having a negativeimpact on the combustion.
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| 7. |
- Aghaali, Habib, 1981-, et al.
(författare)
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Improving Turbocharged Engine Simulation by Including Heat Transfer in the Turbocharger
- 2012
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Ingår i: 2012 SAE International. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE international.
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Konferensbidrag (refereegranskat)abstract
- Engine simulation based on one-dimensional gas dynamics is well suited for integration of all aspects arising in engine and power-train developments. Commonly used turbocharger performance maps in engine simulation are measured in non-pulsating flow and without taking into account the heat transfer. Since on-engine turbochargers are exposed to pulsating flow and varying heat transfer situations, the maps in the engine simulation, i.e. GT-POWER, have to be shifted and corrected which are usually done by mass and efficiency multipliers for both turbine and compressor. The multipliers change the maps and are often different for every load point. Particularly, the efficiency multiplier is different for every heat transfer situation on the turbocharger. The aim of this paper is to include the heat transfer of the turbocharger in the engine simulation and consequently to reduce the use of efficiency multiplier for both the turbine and compressor. A set of experiment has been designed and performed on a water-oil-cooled turbocharger, which was installed on a 2 liter GDI engine with variable valve timing, for different load points of the engine and different conditions of heat transfer in the turbocharger. The experiments were the base to simulate heat transfer on the turbocharger, by adding a heat sink before the turbine and a heat source after the compressor. The efficiency multiplier of the turbine cannot compensate for all heat transfer in the turbine, so it is needed to put out heat from the turbine in addition to the using of efficiency multiplier. Results of this study show that including heat transfer of turbocharger in engine simulation enables to decrease the use of turbine efficiency multiplier and eliminate the use of compressor efficiency multiplier to correctly calculate the measured gas temperatures after turbine and compressor.
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| 8. |
- Agrell, Fredrik, et al.
(författare)
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Control of HCCI During Engine Transients by aid of Variable Valve Timings Through the use of Model Based Non-Linear Compensation
- 2005
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Ingår i: SAE transactions. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0096-736X. ; 114:3, s. 296-310
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Tidskriftsartikel (refereegranskat)abstract
- One of the main challenges with the Homogeneous Charge Compression Ignition, HCCI, combustion system is to control the Start Of Combustion, SOC, for varying load and external conditions. A method to achieve this on a cycle-by-cycle basis is to vary the valve timing based on a feedback signal from the SOC of previous cycles. The control can be achieved with two basic valve-timing strategies named the Overlap- and the IVC-method. The Overlap-method works by trapping of residuals while the IVC-method affects the effective compression ratio. In an earlier paper it has been shown that if the two methods are incorporated into one controller, SOC can be controlled in a relatively large operating window although the transient performance was not sufficient. The reason is that the simple PI-controller cannot be made fast enough to cope with the transients without magnifying the cycle-to-cycle variations of the combustion into instability. In this work a model based control system that features a non-linear compensation, based on the inverse of the non-linear function from valve timings to ignition delay, is suggested and evaluated. The results show good transient performance. Control performance from engine tests is reported. A combined engine and control simulation system is used for the development of the control strategies. The simulations are accomplished with a commercial cycle simulation code linked with a commercial control simulation code. The simulations are iteratively verified against engine test data. Engine tests are conducted on a single cylinder engine equipped with a hydraulic valve system.
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| 9. |
- Ahlinder, Sven, et al.
(författare)
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A study of parameters affecting noise on a heavy duty DI engine
- 2007
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- On a 13 liter Direct Injection Heavy duty diesel engine, noise and cylinder pressure have been measured in order to investigate if noise can be estimated from cylinder pressure. The idea of filtering cylinder pressure to obtain noise has been tested. This idea implies that the engine works as a linear filter. The linear relation between cylinder pressure frequencies and noise frequencies seems quite poor and the method probably does not work on the engine tested. When measuring noise, on the other hand, multivariate low order polynomials work well to study the trade-off between measured noise, fuel consumption, NOx and Soot. This implies that the huge datasets gathered with modern electronically controlled engines can be handled this way. Copyright © 2007 Society of Automotive Engineers of Japan, Inc.
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| 10. |
- Alemahdi, Nika, et al.
(författare)
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Φ-Sensitivity Evaluation of n-Butanol and Iso-Butanol Blends with Surrogate Gasoline
- 2023
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Ingår i: SAE Tecnical papers. - 0148-7191.
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Konferensbidrag (refereegranskat)abstract
- Using renewable fuels is a reliable approach for decarbonization of combustion engines. iso-Butanol and n-butanol are known as longer chain alcohols and have the potential of being used as gasoline substitute or a renewable fraction of gasoline. The combustion behavior of renewable fuels in modern combustion engines and advanced combustion concepts is not well understood yet. Low-temperature combustion (LTC) is a concept that is a basis for some of the low emissions-high efficiency combustion technologies. Fuel Φ-sensitivity is known as a key factor to be considered for tailoring fuels for these engines. The Lund Φ-sensitivity method is an empirical test method for evaluation of the Φ-sensitivity of liquid fuels and evaluate fuel behavior in thermal. iso-Butanol and n-butanol are two alcohols which like other alcohol exhibit nonlinear behavior when blended with (surrogate) gasoline in terms of RON and MON. In this study, first the Lund Φ-sensitivity numbers of iso-butanol and n-butanol at CA50≈3°CA after TDC is measured. CA50 is the rank angle degree at which 50% of total accumulated heat is released. Then, the Lund Φ-sensitivity number of iso-butanol at two later combustion phasing of CA50≈8 & 6 °CA after TDC is evaluated. Finally, the Lund Φ-sensitivity number of volumetric blends of iso-butanol and surrogate gasoline (RON≈87) were measured. The results show the Φ-sensitivity of iso-butanol is lower than n-butanol which means the combustion behavior of iso-butanol is less sensitive to thermal and fuel stratification. The nonlinear behavior of Lund Φ-sensitivity number of iso-butanol blends with surrogate gasoline is observed. As expected, the later combustion phasing lowers the Lund Φ-sensitivity number of the tested fuel and increases the experimental range successfully.
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