| 1. |
- Anderberg, Cecilia, 1963-, et al.
(författare)
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Liner surface improvements for low friction piston ring packs
- 2014
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Ingår i: Surface Topography : Metrology and Properties. - Bristol : Institute of Physics (IOP). - 2051-672X. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- The development of engine components in the automotive industry is governed by several constraints such as environmental legislation and customer expectations. About a half of the frictional losses in an internal combustion engine come from the interactions between the piston assembly and cylinder liner surface. The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over the past few decades. Many non-conventional cylinder liner finishes have been, and are being, developed with the aim to reduce friction losses and oil consumption, but the effects of the surface finish on piston ring pack performance is not well understood. One way of reducing friction in the cylinder system is to reduce the tangential load from the piston ring pack, focusing on the oil control ring. However, the side-effect of this is a disappointingly increased oil consumption. In this study a number of different cylinder liner surface specifications were developed and implemented in test engines with the aim of maintaining the level for oil consumption when decreasing the tangential load for the piston ring pack. To improve our understanding of the result, the same surfaces were evaluated in elastic and elasto-plastic rough contact and hydrodynamic flow simulation models. It is shown that oil consumption is strongly related to surface texture on the cylinder liners and at lower speeds (900–1200 rpm), a 'rougher surface' with a high core (e.g. Sk) and valley roughness (e.g. Svk) results in higher oil consumption. At the medium speed range (1200–3600 rpm), oil consumption continues to dominate for the 'rough' surfaces but with a visible influence of a lower oil consumption for a decreased roughness within the 'rough' surface group. 'Smooth' surfaces with a 'smooth' core (Sk), irrespective of the valley component (Svk), show similar oil consumption. For engine speeds above 3600 rpms, an increase in plateau roughness results in higher oil consumption. Throughout the study, standard roughness parameters were computed to compare with the results from engine testing and simulation. Future work will be directed to continuous optimization between oil consumption and friction. Improving the understanding of the functional cylinder system surfaces' ability to form oil films in the cylinder system opens up opportunities, not only in reducing the tangential load of piston ring packs but also in optimizing oil viscosity in order to reduce friction.
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| 2. |
- Anderberg, Cecilia, 1963
(författare)
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Oil consumption and Friction in a Piston Ring-Cylinder Liner assembly.-A multifunctional Surface Approach
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- About a half of the frictional losses in an internal combustion engine come from the interactions between the piston assembly and cylinder liner surface. The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over the past few decades. Many non-conventional cylinder liner finishes have been, and are being, developed with the aim to reduce friction losses and oil consumption, but the effects of the surface finish on piston ring pack performance is not well understood. One way of reducing friction in the cylinder system is to reduce the tangential load from the piston ring pack, focusing on the oil control ring that is the largest contributor to friction losses among the three piston rings. However, the side effect of this is disappointingly increased oil consumption. To counteract the increase of oil consumption a number of different cylinder liner surface specifications were developed and implemented in test engines with the aim of maintaining a sufficiently low level for oil consumption when decreasing the tangential load for the piston ring pack. The cylinder liner surface and piston ring profile interaction has a function working in the micro scale area and therefore manufacturing of the surfaces is a delicate task. By choosing wrong characterization parameters or wrong manufacturing methods the delicate equilibrium in the interaction between liner surface and ring surface can be broken. An algorithm to assess and quantify the presence of blechmantel was developed. The relative success of the Rq and Rk families of parameters in quantifying liner surfaces were compared and several parameters were found to be so highly correlated as to be redundant. No convincing correlation could be obtained with honing parameters. Topological diagrams helped to distinguish the robustness of parameters. Simulation suggested that low roughness reduces oil consumption but increases friction, while higher roughness produces the opposite effects, and this finding was confirmed by engine tests over a range of speeds. Finally a area scale fractal analysis was performed to investigate the correlation between liner surface areal scale and oil consumption results in order to investigate the scale of functional occurrence. The analysis has given some promising results in finding scale range with good correlations with functional data and ability to discriminate properties in surface geometries.
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| 3. |
- Anderberg, Cecilia, 1963
(författare)
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Towards functional characterisation for cylinder liner surfaces
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The demands on decreased environmental impact from vehicles force the automotive industry to develop engines with reduced engine oil and fuel consumption. Frictional losses in the piston ring cylinder liner system accounts for approximately 20 % of the total frictional losses within an engine. Engine oil consumption is recognized to be a significant source of pollutant emissions. Unburned or partially burned oil in the exhaust gases contribute directly to hydrocarbon and particulate emissions. Engine oil and fuel consumption are to a great extend controlled by the topography of the cylinder liner surface.The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over several decades. Many non-conventional cylinder liner finishes has been and are being developed with the aim to reduce oil- and fuel consumption, but the effects of surface finish on piston ring pack performance is not well understood.To enable the study of impact from cylinder liner topography on cylinder system performance, an improvement in liner finish characterisation is needed to be able to discriminate surface features important for function. Also in manufacturing quality control issues there is a need for surface characterisation methods that are robust and reasonably fast.The purpose of this thesis is to investigate different roughness characterisation systems stability and ability to discriminate surface features. One seemingly obvious useful characterisation method for plateau honed surfaces is the Rk parameter family based on the bearing area curve. But there is a interdependency between the parameters within the parameter family which makes it very difficult to specify a surface that is possible to manufacture in a controlled way. The Rxq family is more promising in describing the different stages in the honing process.Liner surfaces with finer finish show a decrease in oil consumption in engine tests. To be able to produce finer surfaces an introduction of diamond honing tools is required. Honing with diamond tools gives a more robust manufacturing process in terms of surface roughness but there is a increased risk of cold worked material, blechmantel, due to higher honing pressure. A manufacturing quality control method based on SEM pictures and 2D profilometry of cylinder liner surfaces is developed and evaluated. The method is capable of discriminating surface quality but SEM pictures are not optimal for usage in manufacturing plants due to the complexity to obtain comparable pictures of the surfaces.
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| 4. |
- Bergman, Martin, 1985-, et al.
(författare)
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Surface design methodology : challenge the steel
- 2013
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Ingår i: Metrology and Properties of Engineering Surfaces, 2013. - Bristol, UK : Institute of Physics Publishing (IOPP). ; 483:1, s. Art. no. 012013-
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Konferensbidrag (refereegranskat)abstract
- The way a product or material is experienced by its user could be different depending on the scenario. It is also well known that different materials and surfaces are used for different purposes. When optimizing materials and surface roughness for a certain something with the intention to improve a product, it is important to obtain not only the physical requirements, but also the user experience and expectations. Laws and requirements of the materials and the surface function, but also the conservative way of thinking about materials and colours characterize the design of medical equipment. The purpose of this paper is to link the technical- and customer requirements of current materials and surface textures in medical environments. By focusing on parts of the theory of Kansei Engineering, improvements of the companys' products are possible. The idea is to find correlations between desired experience or «feeling» for a product, -customer requirements, functional requirements, and product geometrical properties -design parameters, to be implemented on new improved products. To be able to find new materials with the same (or better) technical requirements but a higher level of user stimulation, the current material (stainless steel) and its surface (brushed textures) was used as a reference. The usage of focus groups of experts at the manufacturer lead to a selection of twelve possible new materials for investigation in the project. In collaboration with the topical company for this project, three new materials that fulfil the requirements -easy to clean and anti-bacterial came to be in focus for further investigation in regard to a new design of a washer-disinfector for medical equipment using the Kansei based Clean ability approach CAA. © Published under licence by IOP Publishing Ltd.
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| 5. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Automotive Applications—Cylinder Liners and Tool Steel Polishing for Injection Moulding of Plastic Parts
- 2024. - 2
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Ingår i: Characterisation of Areal Surface Texture. - Switzereland : Springer Nature. - 9783031593093 - 9783031593109 ; , s. 295-321
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Bokkapitel (refereegranskat)abstract
- Surfaces are vital for a range of functions for automotive components. The visual appearance and cleanability of injection moulded plastic parts depend on the control of the polished mould finish. It is also of interest to reduce oil consumption and frictional losses in internal combustion engines, which are heavily influenced by the quality of the cylinder liner surface. The plateau cross-hatch topography of a cylinder liner consists of a system of grooves of different density, width and depth, some parts covered by folded metal, and some parts totally interrupted and unbalanced as a result of imperfection in the honing process. These grooves are critical for good liner function and need to be quickly and objectively quantified for an efficient surface finish development. A suitable way to do this is to use coherence scanning interferometry and to combine profile and image analysis. Thus, the features/parameters, such as honing angle, balance of honing texture, groove interrupts, width, height and distance between grooves, are successively quantified. Here, these parameters, along with areal surface texture parameters in the published ISO specification standard, were used in three case studies. The first case study is on the effect of the folded metal on the surfaces of run truck liners, the second is an evaluation of the improvements of the surface quality introduced by the diamond honing in production of car liners. In addition, based on the significant parameters of the surface, a general characterisation tool for qualifying the surface quality and determination of the required number of measurements is presented. The third case is implementing the methodologies developed for engine liner characterisation for polished tool steels. The case worked well after it had been modified and adapted to these types of surfaces. Also, the scratch patterns on the polished samples, quantified in terms of width and depth, are important parameters that indicate whether the topography of a polished tool steel surface has reached a sufficient quality level, and supports the monitoring of how the polishing steps affect the surface topography © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.
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| 6. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Characterisation of Cylinder Liner Honing Textures for Production Control
- 2013
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Ingår i: Characterisation of Areal Surface Texture. - Berlin : Springer Berlin/Heidelberg. - 9783642364570 - 9783642364587 ; , s. 281-302
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Bokkapitel (refereegranskat)abstract
- It is of common interest to reduce oil consumption and frictional losses in internal combustion engines, which are heavily influenced by the quality of the cylinder liner surface. The plateau cross-hatch topography of a cylinder liner consists of a system of grooves of different density, width and depth, some parts covered by folded metal, and some parts totally interrupted and unbalanced as a result of imperfection in the honing process. These grooves are critical for good liner function, and need to be quickly and objectively quantified for an efficient surface finish development. A suitable way to do this is to use 3D interference measurements and to combine profile and image analysis. Thus, the features/parameters, such as honing angle, balance of honing texture, groove interrupts, width, height, and distance between grooves, are successively quantified. Here, these parameters, along with areal surface texture parameters in the published ISO specification standard were used in two case studies. The first case study is on the effect of the folded metal on the surfaces of run truck liners and the second is an evaluation of the improvements of the surface quality introduced by the diamond honing in production of car liners. In addition, based on the significant parameters of the surface, a general characterisation tool for qualifying the surface quality and determination of the required number of measurements is presented. © 2013 Springer-Verlag Berlin Heidelberg. All rights are reserved.
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| 7. |
- Dimkovski, Zlate, 1974, et al.
(författare)
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Cylinder Liner Honed Surface Optimisation - a Manufacture-Characterisation-Function Study
- 2007
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Ingår i: Proceedings of the 1st Swedish production symposium.
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Konferensbidrag (refereegranskat)abstract
- In order to comply with increasingly stringent emission standards, engine manufacturers strive to reduce the oil consumption and frictional losses. One of the major contributors to it is the cylinder liner surface. Therefore, it is important to investigate what are the optimal machining parameters to manufacture liner topography with an optimal function. Numerous liners were slide honed, varying the base honing pressure and plateau honing time. The samples of the liners were measured on stylus and interferometer, and characterized by 2D and 3D parameters. The interference measurements were inputted in a flow simulation program and the mean oil flow and hydrodynamic shear stress were calculated for different nominal separations between the ring and liner. The analytical results show that a relatively low base honing pressure and longer plateau honing time give a surface with the lowest mean oil flow and the highest shear stress. A good correlation among the oil flow, shear stress, base honing pressure, Sa, Sk, Svk, and other roughness parameters was also found.
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| 8. |
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| 9. |
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| 10. |
- Dimkovski, Zlate, 1974-, et al.
(författare)
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Quantification of Blechmantel Effect on Wear of Cylinder Bore Microtopography
- 2008
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Ingår i: Proceedings of the 13th Nordic Symposium on Tribology, Nordtrib 2008. - Tampere : Tampere University Press. - 9789521519611 ; , s. 13-
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Konferensbidrag (refereegranskat)abstract
- The presence of cold work material (blechmantel) smeared out on cylinder liners by faulty honing is undesirable as it seals the oil-bearing honing grooves. It is also believed to correlate with increased bore wear, presumably due to its loosening and together with the carbon build-up from the piston’s top land form an increased quantity of abrasive particles. An attempt has been made to estimate the extent of removal of blechmantel for different wear regimes present at the middle and top region (near the top dead centre) of the liner surface using the unworn bottom region as a reference for comparison. A number of truck cylinder liners were axially sectioned after varying periods of engine running under similar conditions of load, engine speed and lubrication. 3D surface measurements were taken at the three regions and a range of standard parameters was extracted. Combining the profile and image analysis, an algorithm was developed to identify and quantify the blechmantel covering the grooves that is most likely to break and act as abrasive wear particles and at the same time it represents the part of blechmantel which covers the most of the surface. It was found out that a mere portion of the blechmantel from the middle and bottom section was removed, while the blechmantel from the top section was greatly removed and thereby it represents one of the possible causes for wear. Axial wear scratches more emphasized on the thrust side of the liner were observed not only through the whole stroke area, but also in the bottom region. The fact that the most of the blechmantel is not removed from the running surface of the liner (except for the very small portion of the polished areas at the dead centres), points out that the blechmantel plays only a minor role on wear of the cylinder liner surfaces.
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