Piston Cylinder Research Articles

Comparison of Proportional and PWM Pneumatic Control in Terms of Positioning and Compressed Air Consumption

In this paper is shown a comparison of proportional pneumatic control and Pulse Width Modulation (PWM) pneumatic control in terms of positioning and compressed air consumption. All experimental tests were performed on a device for lifting and holding of the workpieces, which consists of one vertically mounted rodless cylinder with integrated vacuum gripper. In the case of the proportional pneumatic control, cylinder piston is always positioning in the correct position, but position losses are recurring during the time (in majority of cases, the position loss is 4 mm). As the control system constantly returns the cylinder piston to the desired position, that increases the compressed air consumption. In the case of the PWM pneumatic control, the position error is occurring (in majority of cases, the absolute value of the relative position error is less than 2%), but there is no position loss during the period of workpiece holding, i.e. there is no additional compressed air consumption. The compressed air consumption differential is approximately 18.6%. In addition, in case of Meter-out control in combination with previously defined types of control, the positioning is more accurate but the compressed air consumption slightly increases with decreasing the opening level of the one-way flow control valve.

Evaluation of cut cell cartesian method for simulation of a hook and claw type hydrogen pump

Hook and claw pumps are used for recirculation of excess hydrogen in fuel cells. Optimization of the pump design is essential. Computational Fluid Dynamic (CFD) is an effective method for performance optimization. However, it is difficult to conduct CFD simulation because of the sharp cusp of the rotor profile. Cut cell Cartesian mesh could be the solution to handle this complex and moving geometries. The aim of this paper is to evaluate ANSYS Forte for hook and claw pumps. Firstly, the conservation accuracy of the cut cell cartesian mesh is verified using an adiabatic piston cylinder case. Then, simulation results of hook and claw type pump are compared with experimental data. Finally, simulation results of air and hydrogen are compared. The results show that the CFD simulation of hook and claw pumps using cut cell cartesian mesh could provide an efficient and effective approach for the optimization of the system.

High-pressure homogenization of olivine-hosted CO<sub>2</sub>-rich melt inclusions in a piston cylinder: insight into the volatile content of primary mantle melts

Abstract. Experimental homogenization of olivine-hosted melt inclusions representative of near-primary basic and ultrabasic magmas is a powerful approach to investigate the nature of their source regions and the melting conditions in Earth's mantle. There is growing evidence that the total CO2 contents of olivine-hosted melt inclusions may reach values of the order of a single to several weight percent, especially in intraplate continental basalts. To be able to homogenize melt inclusions with such high CO2 contents, we developed a technique allowing for heat treating of the melt inclusions under hydrostatic pressures up to 3–4 GPa in a piston cylinder, using thick-walled Au80–Pd20 containers and molten NaCl as the surrounding medium for the inclusion-bearing olivines. We applied this technique to olivine phenocrysts from Thueyts basanite, Bas-Vivarais volcanic province, French Massif Central. Thueyts melt inclusions were chosen because of their high CO2 contents, as indicated by up to 1.19 wt % dissolved CO2 in the glasses and by the presence of shrinkage bubbles containing abundant carbonate microcrystals in addition to a CO2 fluid phase. The homogenization experiments were conducted at pressures of 1.5 to 2.5 GPa, temperatures of 1275 and 1300 ∘C, and run durations of 30 min. In all the melt inclusions treated at 2.5 GPa–1300 ∘C and half of those treated at 2 GPa–1300 ∘C, we were able to completely homogenize the inclusions, as indicated by the disappearance of the starting bubbles, and we obtained total CO2 contents ranging from 3.2 wt % to 4.3 wt % (3.7 wt % on average). In all the other melt inclusions (equilibrated at 1.5 or 2 GPa and 1300 ∘C or at 2.5 GPa–1275 ∘C), we obtained lower and more variable total CO2 contents (1.4 wt % to 2.9 wt %). In the inclusions with the highest total CO2 contents, the size of the shrinkage bubble was in most cases small (<5 vol %) to medium (<10 vol %): this is a strong argument in favor of an origin of these melt inclusions by homogeneous entrapment of very CO2-rich basanitic liquids (∼ 4 wt %) at pressures of 2 to 2.5 GPa. The lower total CO2 contents measured in some inclusions could reflect a natural variability in the initial CO2 contents, due for instance to melt entrapment at different pressures, or CO2 loss by decrepitation. An alternative scenario is heterogeneous entrapment of basanitic liquid plus dense CO2 fluid at lower pressures but still at least on the order of 1 GPa as indicated by dissolved CO2 contents up to 1.19 wt % in the glasses of unheated melt inclusions. Whatever the scenario, the basanites from the Bas-Vivarais volcanic province were generated in a mantle environment extremely rich in carbon dioxide.

Mechanical anti-lock braking system using pneumatic system and solenoid valve with low cost manufacturing

PurposeThe Purpose of this study is to prove the possibility of developing low cost mechanical anti – lock braking system (ABS) for the passenger’s safety.Design/methodology/approachThe design methodology of the proposed newer mechanical ABS comprises of two units, namely, the braking unit and wheel lock prevention unit. The braking unit actuates the wheel stopping as and when the driver applies the brake, whereas the wheel lock prevention unit initiates wheel release to prevent locking and subsequent slip/skidding. The brake pedal with master cylinder assembly and double-arm cylinder forms the braking unit, brake pad cylinder, movable brake pad, solenoid valve and dynamo forms the wheel lock prevention unit. The dynamo coupled with the rotor energises/de-energises the solenoid values to direct airflow for applying brake and release it, which makes the system less energy-dependent.FindingsThe braking unit aids in vehicle stops, by locking the disc with the brake pad actuated by a double-arm cylinder. The dynamo energises the solenoid valve to activate the brake pad cylinder piston for applying the brake on the disc. Instantaneously, on applying the brake the dynamo de-energises the solenoid to divert the pneumatic flow for retracting the brake pad thereby minimizing the braking torque. The baking torque reduction revives the wheel rotating and prevents slip/skidding.Originality/valueMechanical ABS preventing wheel lock by torque reduction principle is a novel method that has not been evolved so far. The system was designed with repair/replacement of the parts and subcomponents to support higher affordability on safety grounds.

Carbon recycling efficiency in subduction zones constrained by the effects of H2O-CO2 fluids on partial melt compositions in the mantle wedge

The extent of CO2 transfer from subducting lithologies to the overlying mantle wedge in general and to the arc magma source regions in particular remains debated. The limit of CO2 transfer to the sub-arc mantle could be estimated if the effects of CO2 on the primary hydrous melt compositions of mantle wedge can be assessed in relation to the observed compositions of primitive arc magmas. Here we present new piston cylinder and multi-anvil experiments using Au75Pd25 and Au capsules on four depleted peridotite + H2O ± CO2 starting compositions with 3.5 wt.% H2O and XCO2 [=molar CO2/ (CO2+H2O)] of 0–0.17. Experiments were performed at 2–4 GPa and 1200°C to constrain how the presence of variable CO2 in slab-derived aqueous fluids affects the composition of peridotite partial melts. All experiments consisted of low degree melts (<10 wt.%) in equilibrium with olivine + orthopyroxene ± clinopyroxene. Melts at 2–4 GPa are basaltic for XCO2 of 0–0.10 and become SiO2-poor and CaO-rich at XCO2 > 0.10. Comparison between our experimental partial melt compositions with a global dataset of the most primitive arc magmas suggests that the upper limit of XCO2 in fluids inducing melting in mantle wedges is ∼0.10 at 2–4 GPa. We apply these new constrains to an H2O and CO2 mass balance model for subduction zones and estimate that at least 34–86% of CO2 entering subduction zones bypasses the sub-arc melt generation zone and is subducted to the convecting mantle, either carried by the slab or by the down-dragged limb of the mantle wedge directly above the slab.

Analysis of and Experimental Research on a Hydraulic Traction System Based on a Digital Hydraulic Transformer.

In this study, we designed a new type of digital hydraulic transformer using four gear–pump/motor units with a displacement ratio of 20:21:22:23 and two control valve groups that consist of four solenoid directional valves. The driving gear shafts of the four gear–pump/motor units are fixedly connected to achieve synchronous rotation. The two control valve groups are respectively installed through an integrated valve block on the inlet and outlet of each gear–pump/motor unit. With the objective of reducing the installed power and energy consumption of hydraulic traction systems, we propose a new energy-saving hydraulic system based on a digital hydraulic transformer. This hydraulic system uses a digital hydraulic transformer as a pressure/flow control element. By controlling the power on/off states of eight solenoid directional valves, the digital hydraulic transformer can realize a change in output flow and then a change in speed of the hydraulic cylinder piston rod. Through the theoretical derivation and simulation analysis of the hydraulic system pressure/flow change process, and the experimental verification of the built hydraulic traction system based on the experimental platform, a conclusion is drawn that the proposed digital hydraulic transformer can change the output pressure/flow of a hydraulic system through a binary digital control, verifying the feasibility of the pressure change principle of the designed digital hydraulic transformer and the rationality of the hydraulic traction system circuit.

Determination of the H2O‐Saturated Solidus of Albite by Electrical Conductivity

AbstractIn the study of subduction zone processes, there has been much debate on slab dehydration against slab melting, as well as on flux melting of the mantle wedge against metasomatism and a prolonged period of storage and heating before mantle melting. H2O‐saturated solidus of rock is critical to the debate. Unfortunately, there is a significant discrepancy in H2O‐saturated solidus between different experimental studies, mainly due to the difficulty in distinguishing hydrous melt from aqueous fluid in quenched experimental products. In this study, we developed a new approach to locating H2O‐saturated solidus of rock systems by monitoring the electrical conductivity of the system in situ. A mixture of albite and &gt;10 wt% H2O was heated stepwise in the range of 0.35–1.7 GPa in a piston cylinder apparatus. A jump in electrical conductivity (up to 1.8 log units) was observed over a small temperature interval (10–20°C). The temperature corresponding to the electrical jump decreased from 790 ± 10°C at 0.35 GPa to 640 ± 10°C at 1.7 GPa, in good agreement with previously reported H2O‐saturated solidus of albite. Examination of the experimental products quenched immediately after observation of the electrical conductivity jump confirmed the occurrence of albite melting. Our experimental results suggest that the electrical conductivity jump serves as a good indicator for rock melting under H2O‐saturated conditions, and this in situ approach can overcome the ambiguity in phase identification in quench experiments. This new approach has the potential to solve the discrepancy over H2O‐saturated solidus of a variety of rock systems and shed light on subduction zone processes.

Coupling of heat transfer and lubrication of cylinder liner-piston skirt conjunction and low-friction temperature strategy of cylinder liner

PurposeThis paper aims to understand the influence of cylinder liner temperature on friction power loss of piston skirts and the synergistic effect of cylinder liner temperature on lubrication and heat transfer between piston skirt and cylinder liner.Design/methodology/approachA method to calculate the influence of cylinder liner temperature on piston skirt lubrication is proposed. The lubrication is calculated by considering the different temperature distribution of the cylinder liner and corresponding piston temperature calculated by a new multilayer thermal resistance model. This model uses the inner surface temperature of the cylinder liner as the starting point, and the starting temperature corresponding to different positions of the piston is calculated using the time integral average. Besides, the transient heat transfer of mixed lubrication is taken into account. Six temperature distribution schemes of cylinder liner are designed.FindingsSix temperature distributions of cylinder liner are designed, and the maximum friction loss is reduced by 34.4% compared with the original engine. The increase in temperature in the second part of the cylinder liner will lead to an increase in friction power loss. The increase of temperature in the third part of the cylinder liner will lead to a decrease in friction power loss. The influence of temperature change in the third part of the cylinder liner on friction power loss is greater than that in the second part.Originality/valueThe influence of different temperature distribution of cylinder liner on the lubrication and friction of piston skirt cylinder liner connection was simulated.

Flow factor modeling of combustion engine ring and cylinder components in mixed hydrodynamic lubrication

This work employees the modification of the Reynolds equation for computational efficiency by analyzing rough surfaces in the hydrodynamic flow regime through the use of flow factors. This analysis is aimed towards modeling the surface interactions and pressure variations across power cylinder components of an internal combustion engine, namely the piston ring and cylinder wall. The Patir and Cheng equations are for general surfaces that accounts for the overall effect of roughness and anisotropic structure. However, rough surfaces are not fully characterized by these two parameters and therefore the aim of this paper was to provide flow-factors specific to the cross-hatched cylinder liner surfaces and piston ring interface. These interacting surfaces were measured directly through the use of a profilometer. Average flow factors are derived via full deterministic solution of the Reynolds equation over rough surfaces to model the pressure and shear variations relative to smooth surfaces. These flow factors can then be used to consider the effect of roughness in lubrication problems without deterministically modeling roughness.

Macro-texture in hydrodynamic lubrication: Effects of dimple parameter, density and distribution

Surface texturing, a well-known method to increase tribo-pair tribological performance, is widely used and of great importance in industrial manufacturing. By designing reasonable surface texture on two contact surfaces, the load-carrying capacity, wear resistance, and coefficient of friction of the tribo-pairs can be significantly improved. To investigate the influence of the macro-texture, millimeter magnitude, on the tribology performance, a large number of simulation cases were carried out in this work. And the influence of texture parameters including the ellipse aspect ratio, the depth-to-diameter ratio, density, and distribution on tribology performance was studied using the hydrodynamic lubrication model which was verified through a sample experiment of piston ring and cylinder liner tribo-pairs. In addition, a Taguchi algorithm was used to find the most suitable texture parameters. The results show that the influence of density on the coefficient of friction and load-carrying capacity is of significance and 20% density is sufficient for tribology performance. Dimple size and distribution had a more significant influence on tribology performance.

New Insights into Abnormal Combustion Phenomena Induced by Diesel Spray-Wall Impingement under Engine-Relevant Conditions

High altitude and low temperature is the common extreme environment for internal combustion engines. Under such operating conditions, heavy-duty diesel engines often suffer from serious abnormal combustion, such as knocking combustion, which results in piston crown breakdown and cylinder head erosion. Spray-wall impingement and pool fires are considered potential causes; however, the detailed mechanism remains poorly understood owing to the lack of research data. In this study, for the first time, the destructive abnormal combustion induced by diesel spray-wall impingement was identified using an optical rapid compression machine under engine-relevant conditions at high altitudes. Combining instantaneous pressure and temperature measurements with simultaneously recorded high-speed photography gives useful insights into understanding the detailed combustion processes. The experimental results show that depending on the extent of diesel spray-wall impingement, supersonic detonation-like reaction fronts featuring bright luminosity can be observed. The propagation of these reaction fronts in-cylinder results in severe pressure oscillations with an amplitude approaching hundreds of atmospheres, which is like the super-knock events in boosted direct-injection spark-ignition engines. Further parametric analysis indicates that the interplay between the diffusion combustion controlled by diesel spray and the premixed combustion dominated by attached film evaporation results in the formation of abnormal combustion. Destructive reaction fronts tend to occur at a prolonged ignition delay time, which facilitates the mixing between diesel evaporation and hot air.

ПРИМЕНЕНИЕ КОМБИНИРОВАННОГО УПЛОТНЕНИЯ ДЛЯ СНИЖЕНИЯ НАГРУЗКИ, ДЕЙСТВУЮЩЕЙ НА ЦИЛИНДРОПОРШНЕВОЕ УПЛОТНЕНИЕ

In this scientific paper, the importance of the life of the cylinder piston seal for medium and high pres-sure reciprocating compressor units is considered. The scheme of forces acting on the seal (valid for both piston rings and cuff seals) is considered. The basic calculation formulas are given and a prom-ising design of a combined seal is proposed to increase the service life of the entire compressor unit operating mainly without lubrication of the flow part of the cylinder. To solve this problem, a hypothe-sis is put forward about the possibility of reducing the load on the seal by throttling the gas, thereby not reducing the performance of the piston unit. In addition, diagrams and photos of a promising de-sign of a combined seal (four combination options) are given. A detailed description of the experi-mental stand for determining the pressure drop (load) acting on the cuff seal is made. The procedure for conducting an experimental study is also described. As a result, it is found that the use of a com-bined seal allows to reduce the pressure drop on the first seal by about two times from 2 MPa to 1.1 MPa. Thus, the service life of the seal, theoretically, increases proportionally to the decrease in the pressure drop, also by two times.

A Triboelectric Piston–Cylinder Assembly with Condition‐Monitoring and Self‐Powering Capabilities

The condition monitoring of piston–cylinder‐reciprocating machinery usually relies on vibration and acoustic sensors installed on the outer surface of cylinders. However, vibration and acoustic signals are susceptible to external interference from other accessories, and require an external power supply, which limits its widespread application. Herein, based on the lateral sliding mode of triboelectric nanogenerator (TENG), a novel reciprocating device with condition‐monitoring and self‐powering capabilities is proposed, called piston–cylinder triboelectric nanogenerator (PCTN). The effects of different factors, including mean piston speed, number of piston rings, materials of piston ring and cylinder, on the output characteristics of PCTN are investigated, respectively. Two typical fault cases, that is, piston ring missing and coil fracture, are investigated to verify the condition‐monitoring capability of PCTN. Piston ring missing faults can be effectively identified based on the variations in peak and root‐mean‐square (RMS) values of short‐circuit current (I sc). Coil fracture faults can be identified and located by analyzing changes in time–domain curve and time–‐frequency spectrum of I sc. Herein, a theoretical and experimental basis for the widespread application of PCTN in reciprocating machinery is provided.

Development of a hybrid piston cylinder cell for quasielastic neutron scattering experiments up to 1 GPa

ABSTRACT We have developed a hybrid piston cylinder cell for quasielastic neutron scattering (QENS) experiments up to about 1 GPa. It consists of a fretted cylinder made of the high tensile steel (SNCM439) liner and the Al alloy (NA700) jacket. Performance tests revealed that the cell can withstand a pressure of 0.8 GPa without irreversible damage and has 4.4 times larger neutron transmission at 3.14 meV (5.10 Å in wavelength) than that of a conventional CuBe monobloc cylinder. Combined with the sample assembly devised for suppressing multiple scattering, high quality QENS spectra of water were obtained up to 0.8 GPa. This study illustrates the efficacy of the hybrid cylinders not only for increasing maximum available pressure but also manipulating the available pressure and the signal intensity, depending on the purpose of the experiments.

COH-fluid induced metasomatism of peridotites in the forearc mantle

Devolatilization of subducting lithologies liberates COH-fluids. These may become partially sequestered in peridotites in the slab and the overlying forearc mantle, affecting the cycling of volatiles and fluid mobile elements in subduction zones. Here we assess the magnitudes, timescales and mechanism of channelized injection of COH-fluids doped with {mathrm{Ca}}_{mathrm{aq}}^{2+}, {mathrm{Sr}}_{mathrm{aq}}^{2+} and {mathrm{Ba}}_{mathrm{aq}}^{2+} into the dry forearc mantle by performing piston cylinder experiments between 1–2.5 GPa and 600–700 °C. Cylindrical cores of natural spinel-bearing harzburgites were used as starting materials. Based on mineral assemblage and composition three reaction zones are distinguishable from the rim towards the core of primary olivine and orthopyroxene grains. Zone 1 contains carbonates + quartz ± kyanite and zone 2 contains carbonates + talc ± chlorite. Olivine is further replaced in zone 3 by either antigorite + magnesite or magnesite + talc within or above antigorite stability, respectively. Orthopyroxene is replaced in zone 3 by talc + chlorite. Mineral assemblages and the compositions of secondary minerals depend on fluid composition and the replaced primary silicate. The extent of alteration depends on fluid CO2 content and fluid/rock-ratio, and is further promoted by fluid permeable reaction zones and reaction driven cracking. Our results show that COH-fluid induced metasomatism of the forearc mantle is self-perpetuating and efficient at sequestering {mathrm{Ca}}_{mathrm{aq}}^{2+}, {mathrm{Sr}}_{mathrm{aq}}^{2+}, {mathrm{Ba}}_{mathrm{aq}}^{2+} and CO2aq into newly formed carbonates. This process is fast with 90% of the available C sequestered and nearly 50% of the initial minerals altered at 650 °C, 2 GPa within 55 h. The dissolution of primary silicates under high COH-fluid/rock-ratios, as in channelized fluid flow, enriches SiO2aq in the fluid, while CO2aq is sequestered into carbonates. In an open system, the remaining CO2-depleted, Si-enriched aqueous fluid may cause Si-metasomatism in the forearc further away from the injection of the COH-fluid into peridotite.

FEA Analysis and Experimental Investigation of the Ceramic Coating on Aluminum Piston Material By Plasma Spray Coating Technique

Abstract: Functionally graded materials are of widespread interest because of their superior properties such as corrosion, erosion and oxidation resistance, high hardness, chemical and thermal stability at cryogenic and high temperatures. These properties make them useful for many applications, including Thermal Barrier Coating (TBC) on metallic substrates used at high temperatures in the fields of aircraft and aerospace, especially for thermal protection of components in gas turbines and diesel engines. The application of TBC reduces the heat loss to the engine cooling-jacket through the surface exposed to the heat transfer such as the cylinder head, liner, piston crown and piston rings. The insulation of the combustion chamber with ceramic coating affects the combustion process and, hence, the performance and exhaust emissions characteristics of the engines improve. In this project, the main emphasis is placed on the study of thermal behavior of functionally graded coatings obtained by means of using a commercial code, ANSYS on aluminum and steel piston surfaces and the results are verified with numerical and experimental works. Keywords: Thermal Barrier Coating, Piston, Insulation, Corrosion, ANSYS, engine cooling-jacket.

Investigation of dynamic processes in the hydraulic system of clamping the staffs of the segment unwinder of the unit of aggregation of rolls pipe welding machine 20-114

In the technological line for the production of small diameter pipes used segment un-winder staffs with a cantilever drum and additional support. The experience of its operation has shown that one of its main shortcomings is the unsatisfactory operation of the hydraulic system clamping staffs. In the hydraulic clamping system of the staffs there are increased dynamic loads, which lead to the failure of components and elements of the hydraulic system. The layout of the hydraulic clamping system of the headquarters is made for design and technological rea-sons, without taking into account the influence of pipeline lengths on the nature of dynamic processes in the hydraulic system. In addition, the hydraulic system uses spool hydrodistributors with electro-hydraulic control, the operation time of which is practically not subject to regulation. Based on the analysis of known mathematical models for the study of dynamic processes in hydraulic systems, it was concluded that as a mathematical model that takes into account the design and operation of the hydraulic clamping system staffs finite-difference method in a sys-tem of ordinary differential equations with boundary conditions described by algebraic equations. A basic dynamic model has been created, which allows to analyze with high relia-bility the behavior of the hydraulic system of the clamping mechanism of the staff in the segment unwinder of the rolls, which is exposed to different nature in a wide range of mode parameters. Simulink MATLAB software environment was used to effectively solve this problem. During the implementation of the mathematical model, a study of the modes of operation of the hydraulic system of the clamping mechanism of the staff was performed. It was found that at the end of the working and reverse strokes of the clamping mechanism of the roll in the end posi-tions there are dynamic loads in the hydraulic system that reach the maximum allowable values. In addition, it was found that during the acceleration of the piston of the hydraulic cylinder during operation and reverse, although there are no dangerous loads, but there are rapid fluctuations in pressure in the cavities of the hydraulic cylinder. Theoretical studies of the modes of operation of the hydraulic clamping system of the staff in the segment unwinder with different operating times of the control valve. As a result of the study of transients in the unwinding hydraulic system with different operating times of the hydraulic distributor, its ra-tional operating time was recommended, which is 0.20 seconds when opening and 0.15 sec-onds when closing.

Measurement of Piston Friction with a Floating Liner Engine for Heavy-Duty Applications

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;The further increase in the efficiency of heavy-duty engines is essential in order to reduce CO&lt;sub&gt;2&lt;/sub&gt; emissions in the transport sector. This is also valid for the future use of alternative fuels, which can be CO&lt;sub&gt;2&lt;/sub&gt;-neutral, but can cause higher total costs of ownership due to higher prices and limited availability. In addition to thermodynamic optimization, the reduction of mechanical losses is of great importance. In particular, there is a high potential in the piston bore interface, since continuously increasing cylinder pressures have a strong influence on the frictional and lateral piston forces. To meet these future challenges of increasing heavy-duty engine efficiency, AVL has developed a floating liner engine for heavy-duty applications based on its tried and tested passenger car floating liner concept. This article describes the concept of the friction single-cylinder engine developed to measure both the frictional forces and the lateral forces that occur between the piston assembly and cylinder liner during fired engine operation. Four force sensors convert the floating movement of the liner group into the corresponding frictional force. Due to the crank angle based measurement, a very detailed analysis of measures to increase mechanical efficiency of the piston bore interface is possible. In addition, the frictional power can be derived and used to evaluate the CO&lt;sub&gt;2&lt;/sub&gt; potential of the technologies investigated. The design of the single-cylinder engine has a high degree of flexibility to enable quick component changes and the use of different cranktrains. In a first study, a variation in the crankshaft offset and the potential of this measure to increase engine efficiency are investigated. The results show a clear influence of the cranktrain geometry on the lateral piston force and also on the frictional force during the upstrokes and downstrokes. This measurement campaign confirms the possibilities of the system to contribute to the development of future highly efficient heavy-duty engines.&lt;/div&gt;&lt;/div&gt;

Analysis of the Piston Group Friction in a Single-Cylinder Gasoline Engine When Operated with Synthetic Fuel DMC/MeFo

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Synthetic fuels for internal combustion engines offer CO&lt;sub&gt;2&lt;/sub&gt;-neutral mobility if produced in a closed carbon cycle using renewable energies. C1-based synthetic fuels can offer high knock resistance as well as soot free combustion due to their molecular structure containing oxygen and no direct C-C bonds. Such fuels as, for example, dimethyl carbonate (DMC) and methyl formate (MeFo) have great potential to replace gasoline in spark-ignition (SI) engines. In this study, a mixture of 65% DMC and 35% MeFo (C65F35) was used in a single-cylinder research engine to determine friction losses in the piston group using the floating-liner method. The results were benchmarked against gasoline (G100). Compared to gasoline, the density of C65F35 is almost 40% higher, but its mass-based lower heating value (LHV) is 2.8 times lower. Hence, more fuel must be injected to reach the same engine load as in a conventional gasoline engine, leading to an increased cooling effect. To determine this effect, the temperatures of the cylinder liner and piston of the research engine were measured. Depending on the load point, friction losses were reduced by up to 12.6% compared to gasoline operation. Although the floating-liner engine is operated with port fuel injection (PFI), the temperatures of the cylinder liner dropped by up to 4°C and those of the piston by up to 8°C. C65F35 therefore not only shows decreased emissions, but also leads to a reduction in friction losses, mainly due to the lower temperatures in the combustion chamber.&lt;/div&gt;&lt;/div&gt;

Modeling and experimental investigation of wear and roughness for honed cylinder liner during running-in process

The tribological property of piston ring and cylinder liner has a great influence on exhaust emissions and service performance of internal combustion engines. To explore the effects of surface topography on tribological property of coated piston ring and honed cylinder liner, the hydrodynamic contact model, asperity contact model and wear model during running-in process are established. Considering the non-Gaussian property of rough surfaces into the contact models, the influences of surface parameters on contact pressure are investigated. Due to the influence of operational condition on lubrication performance, the degradation rate of oil is taken into the wear model. Based on this, the change characteristics of the wear process, coefficient of friction and roughness are investigated. To verify the validity of the proposed models, the tribological test is conducted. The results show that the numerical results are in good agreement with the experimental results, and reasonable surface parameters can improve the anti-wear performance of the system during running-in process.