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As a measure to combat climate change, the development of highly efficient internal combustion engines is an important issue. The opposed piston engine is one of the engine types that can achieve high efficiency because of its structure, which enables reduction of cooling loss and long stroke. In this study, I developed a new 2-stroke opposed piston engine and investigated design and development method for a basic general-purpose engine. In addition, combustion stability was evaluated exhaust characteristics under without load conditions were studied to evaluate the engine characteristics using an actual engine.

The paper presents the results of the bench tests to measure mechanical vibrations of a new aircraft opposed piston engine with reciprocating pistons. The PLZ-100 engine is a three-cylinder, six-piston, two-shaft drive unit with a two-stroke diesel cycle. This type of engine is dedicated for powering light aircraft, e.g. autogyros. The tests were carried out on a test bench at the Lublin University of Technology. The engine was loaded with constant torque, for several fixed values of rotational speed of a crankshaft. The angle of the start of diesel injection was changed for each of the rotational speeds. The mechanical vibrations that accompanied the operation of this drive unit were recorded with three measurement transducers and a National Instruments conditioning system. Each of the transducers was mounted on a different axis of the engine. The signals were analyzed from their courses with the DIAdem software. The results were the courses of effective speed and vibration acceleration to conduct a vibration-acoustic evaluation of the PLZ-100, detect and prevent various types of defects or failures.

Opposed-piston, two-stroke engines reveal degrees of freedom that make them excellent candidates for next generation, highly efficient internal combustion engines for hybrid electric vehicles and power systems. This article reports simulation results that explore the influence of key control and geometrical parameters, specifically crankshaft phasing and intake and exhaust port height-to-stroke ratios, in obtaining best thermal efficiency. A model of a 0.75 L, single-cylinder opposed-piston two-stroke engine is exercised to predict fuel consumption as engine speed, load, crankshaft phasing, intake and exhaust port height-to-stroke ratios, and stoichiometry are varied for medium-duty truck and range extender applications. Under stoichiometric operation, optimal crankshaft phasing is seen at 0–5°, lower than reported in the literature. If stoichiometric operation is not mandated, best fuel consumption is achieved at an air-to-fuel equivalence ratio λ = 1.25 and 5–10° crankshaft phase angle, enabling a ~10 g/kWh (~4%) improvement in average brake-specific fuel consumption across medium-duty truck operating points. In range extender form, the engine provides 30 kW output power in accordance with a survey of range extender engines. In this role, there is a clear distinction between low-speed, high-load operation and vice versa. The decision as to which is more appropriate would be based on minimizing total owning and operating cost, itself a trade-off between better thermal efficiency (and thus lower fuel cost) and greater durability.

This paper presents the modeling and control of an opposed piston (OP) engine in a novel hybrid architecture. The OP engine was selected for this work due to the inherent thermody-namic benefits and the balanced nature of the engine. The typical geartrain required on an OP engine was exchanged for two electric motors, significantly reducing friction and decoupling the crankshafts. By using the motors to control the crankshaft motion profiles, this configuration introduces capabilities to dynamically vary compression ratio, combustion volume, and scavenging dynamics. To realize these opportunities, a model of the system capturing the instantaneous engine dynamics is essential along with methodology to regulate the crankshaft’s rotational dynamics utilizing the electric motors. The modeling presented here couples a 1D model capturing the gas exchange process during scavenging and a 0D model of the crankshaft dynamics and the heat release profile due to combustion. With the use of this model, a linear quadratic controller with reference feedforward was designed to track the crankshaft motion trajectory. Experimental results are used to validate the model and controller performance. These results highlight the sensitivity to model uncertainty at points with high cylinder pressure, leading to large differences in control input near minimum volume. The proposed controller is, however, still able to maintain tracking error for crankshaft position below ± 1 degree.

The article presents an analysis of the design of cooling liquid pumps for a compression-ignition aircraft engine. A 100 kW twin- charged, two-stroke, liquid-cooled engine has 3 cylinders and 6 opposed-pistons. In the first part of the study, the amount of heat needed to be removed by the cooling system was estimated to obtain the required volumetric flow rate. Then, the design of automotive cooling liquid pumps for compression-ignition engines with a Common Rail power supply system and power of about 100 kW was analyzed. The aim of the analysis was to select a suitable pump for applications in the aircraft compression-ignition engine. 5 constructions of different shape, diameter and width of the working rotor were selected. The pressure and volume flow rate were determined for a given rotational speed of the pump on a specially built stand. The operation maps of individual pumps were created to select the most efficient types of pumps.

The paper presents an analysis of the constructions of oil pumps for an aircraft compression ignition engine. It is a two-stroke liquid-cooled engine with a power of 100 kW. The system has 3 cylinders and 6 opposed pistons. The paper estimates the required oil pump capacity to make the engine components well-lubricated. Next, automotive oil pumps for diesel engines are analyzed to select a correct pump for aircraft diesel engine applications. Three pump constructions of different constructions and dimensions of a rotor were selected. A measurement bench was designed and built to test these oil pumps in the range of pump shaft speeds from 0 to 4500 rpm and volumetric flow rate up to 150 l/min. The bench also enables stabilization of oil temperature at the required level within the range from 30 to 120oC. In addition, flow resistance through engine slide bearings was simulated by changing the position of a throttling valve at the pump output to regulate pressure in the range of 0–700 kPa. The obtained capacity characteristics of individual pumps versus on oil pressure and temperature allowed us to find an appropriate oil pump to make individual engine nodes well-lubricated.

The paper presents the research results of the injector construction with the modified injection nozzle. The injector is designed for a prototype opposed-piston aircraft diesel engine. The measurements were based on the Mie scattering technique. The conditions of the experiment corresponded to maximum loads similar to those occurring at the start. The measuring point was selected in line with the analysis of engine operating conditions: combustion chamber pressure at the moment of fuel delivery (6 MPa) and fuel pressure in the injection rail (140 MPa). The analysis focused on the average spray range and distribution, taking into account the differences between holes in the nozzle. As a result of the conducted research, the fuel spray range was defined with the determined parameters of injection. The fuel spray ranges inside the constant volume chamber at specific injection pressures and in the chamber were examined, and the obtained results were used to verify and optimize the combustion process in the designed opposed-piston two-stroke engine.

This paper presents measurements and analysis of vibrations of an aircraft compression ignition engine with opposed pistons. New construction of 100 kW engine is designed for propelling gyroplanes, drones and ultralight aircrafts. The engine is in line with the new trend in the development of engines for aircraft propulsion, which adapts the developed technology of automotive engines and the new arrangement of cylinders. The results are based on the vibration spectrum of the power unit in three directions. The method of identification of peak amplitude frequencies for the vibration spectrum is presented. Knowledge of the frequency of vibrations generated by the engine is essential for its correct installation and the selection of supports and vibration isolators. Vibration analysis provides information about the dynamic state of the motor during operation.

Recent announcements regarding the phase out of internal combustion engines indicate the need to make major changes in the automotive industry. Bearing in mind this innovation trend, the article proposes a new approach to the engine design. The aim of this paper is to shed a new light on the forgotten concept of axial engines with wobble plate mechanism. One of their most important advantages is the ease of use of the opposed piston layout, which has recently received much attention. Based on several years of research, the features determining the increase in mechanical efficiency, lower heat losses and the best scavenging efficiency were indicated. Thanks to the applied Variable Compression Ratio (VCR), Variable Angle Shift (VAS) and Variable Port Area (VPA) systems, the engine can operate on various fuels in each of the Spark Ignition (SI), Compression Ignition (CI) and Homogeneous Charge Compression Ignition (HCCI)/Controlled Auto Ignition (CAI) modes. In order to quantify the potential of the proposed design, an initial research of the newest PAMAR 4 engine was presented to calculate the torque curve at low rotational speeds. The achieved torque of 500 Nm at 500 rpm is 65% greater than the maximum torque of the OM 651 engine of the same 1.8 L capacity. The findings lead to the conclusion that axial engines are wrongfully overlooked and can significantly improve research on new trends in pollutant elimination.

Current commercial and heavy-duty powertrains are geared towards emissions reduction. Energy recovery from exhaust gases has great potential, considering the mechanical work to be transferred back to the engine. For this purpose, an additional turbine can be implemented behind a turbocharger; this solution is called turbocompounding (TC). This paper considers the adaptation of turbine wheels and gearboxes of small turboshaft and turbojet engines into a two-stage TC system for a six-cylinder opposed-piston engine that is currently under development. The initial conditions are presented in the first section, while a comparison between small turboshaft and turbojet engines and their components for TC is presented in the second section. Based on the comparative study, a total number of 7 turbojet and 8 turboshaft engines were considered for the TC unit.

The purpose of this project was to develop a low-cost OP engine, 4-stroke, gasoline by joining two single-cylinder reciprocating internal combustion engines with side valves on the block, removing the heads. The chosed engine was Model EY15 of Robin America. Joining these two engine blocks together made possible to build an opposed-piston engine (OPE) with two crankshafts. In this new engine, the combustion chamber is confined to the space inside the cylinder between the piston heads and the chamber between the valves. The pistons move in the cylinder axis in opposite directions, a feature typical of opposed-piston engines. After building the engine, parameters characteristic of the OPE, such as: rotational speed, torque, fuel consumption and emissions, were measured on an Eddy currents dynamometer. With the collected data, power, specific consumption and overall efficiency were calculated, allowing to conclude that the motor with the opposed-piston configuration is less expensive and is more powerful. The development of the opposed-piston engine in this project has shown that it is feasible to build one engine from a different one already in use, reducing the manufacturing and development costs. In addition, higher power can be obtained with better specific fuel consumption and less vibration.

This study provides a comparison of a linear and unscented Kalman filter to estimate the dynamics of a two-stroke opposed piston engine. These engines maintain several advantages over conventional internal combustion engines including reduced heat transfer, higher power to weight ratio, and a larger expansion ratio. Additionally, a crank angle phasing is introduced between the two cranks to improve scavenging efficiency. However, the coupling of the two crankshafts through a large geartrain can cause high amounts of noise and vibration harshness (NVH) and mechanical efficiency losses. By removing the geartrain and controlling the decoupled crankshafts with motor-generators, the NVH can be minimized while maintaining the benefits of crank angle phasing. To control the input torque of the motors to the engine, accurate estimations of the crankshaft position and dynamics are necessary. While the unscented Kalman filter exhibits lower estimation error, the filter is sensitive to model uncertainty relating to cylinder pressure, demanding further investigation of the robustness of the nonlinear filter.

The Achates Power Inc. (API) opposed-piston (OP) engine architecture provides fundamental advantages that increase thermal efficiency over current poppet valve 4 stroke engines. In this paper, the combustion performance of diesel and gasoline compression ignition (GCI) combustion in a medium-duty, OP engine are shown. By using GCI, NOx and/or soot reductions can be seen compared with diesel combustion at similar or increased thermal efficiencies. The results also show that high combustion efficiency can be achieved with GCI combustion with acceptable noise and stability over the same load range as diesel combustion in an OP engine.

This paper examines the selected constructions of piston for aircraft CI engines and discusses tendencies in a development of piston designs. The paper addresses the question of using new materials and coatings to improve quality of pistons and the study of heat transfer and methods to absorb heat from a piston by means of cooling ducts. The selected materials were examined in terms of their advantages and drawbacks. The paper discusses different shapes of piston heads and their impact on combustion as well as indicates other factors behind parameters of combustion and toxic emission like injector shape types, lubrication types and clearances in the combustion chamber.

In the paper, numeric calculations relating to the influence of engine speed on thermal stresses of the piston in a turbocharged diesel engine in the initial phase of its work were carried out. The calculations were based on experimental studies and the data resulting from them. They were made using a geometrical model of the piston in a turbocharged diesel engine with a capacity of 2,300 cm3, with a direct fuel injection to the combustion chamber and a power rating of 85 kW. Modelling of the thermal stresses of the piston was carried out for the engine speed n=2,000 min-1 and n=4,250 min-1.

Paper presents a method of calculating the temperature distribution in cylinder for a 2-stroke, opposed-piston (OP) internal combustion engine (ICE). Development of such machines has been very limited after World War II due to technological and ecological problems [9], therefore progress in numerical modeling for analyzing highly boosted OP engines was also halted. Current technology permits returning to the OP arrangement, where due to better combustion chamber shape it is potentially possible to achieve higher thermodynamic efficiency than in arrangement with the cylinder head [9, 10]. Authors decided to use a general purpose CFD-program (in this case Ansys Fluent) coupled with additional tools to calculate conjugated heat transfer between the load in the cylinder and the cylinder itself to get a 3D temperature distribution in solid body.

An internal combustion engine with opposed piston engine (OPE) develops higher power density than any other conventional internal combustion engine by virtue of its design. A Two stroke OPE gives two power stroke within 3600 of crank revolution which indicates the higher power density. But this extra power also results in large amount of forces gets transmitted to both the crankshaft amounting to large unbalance in the engine. Hence for a smoother and noise free performance, engine should be dynamically balanced. So balancing is one of the main criteria for better performance. In this paper the dynamic analysis was performed by varying the linkage dimensions of OPE for balance OPE. The analytical calculation of inertia forces and dimensions for linkages has been compared with software based results, depending on pressure crank angle plot for two stroke engine.

[EN] The potential of plug-in hybrid electric vehicles (PHEV) to reduce greenhouse gas emissions highly depends on the vehicle usage and electricity source. In addition, the high costs of the battery pack and electric components suppose a challenge to the vehicle manufacturers. However, the internal combustion engine complexity can be reduced due to its lower use as compared to the no-hybrid vehicles. This work evaluates the use of a new opposed piston 2-stroke engine, based on rod-less innovative kinematics, in a series PHEV architecture based on rod-less innovative kinematics along different driving routes in Europe. A 0D-vehicle model fed with experimental tests is used. The battery size is optimized under homologation conditions for two different vehicle types. The optimum case is tested in several real driving conditions under different vehicle modes and battery states of charge. The main contribution of this work is the demonstration of the potential to reduce the vehicle CO2 emissions and cost with an innovative 2-stroke engine. The results show that 24 kWh is the optimum battery size for both vehicle platforms. Charge depleting mode shows 70% of CO2 tailpipe reduction in urban cycles and 22% in long travels compared to the no-hybrid version. Charge sustaining mode results show a CO2 tailpipe reduction of 20% in urban cycles and 2% in long distance travels with respect to the no-hybrid version. In spite of the CO2 contribution of the battery manufacturing, the results show a reduction of LCA CO2 emissions in 52% in charge depleting and 7% charge sustaining against the no-hybrid case., This work has been partially supported by "Conselleria de Innovacion, Universidades, Ciencia y Sociedad Digital de la Generalitat Valenciana" through grant number GV/2020/017. The authors acknowledge FEDER and Spanish Ministerio de Economia y Competitividad for partially supporting this research through TRANCO project (TRA2017-87694-R). The authors want to thank INNengine for providing the engine and the help in the experimental campaign. Lastly, acknowledge to Gamma Technologies for the numerical simulation support and provide the GT-RealDrive licenses

The Achates Power Inc. (API) Opposed Piston (OP) Engine architecture provides fundamental advantages that increase thermal efficiency over current poppet valve 4 stroke engines. In this paper, combustion performance of diesel and gasoline compression ignition (GCI) combustion in a medium duty, OP engine are shown. By using GCI, NOx and/or soot reductions can be seen compared to diesel combustion at similar or increased thermal efficiencies. The results also show that high combustion efficiency can be achieved with GCI combustion with acceptable noise and stability over the same load range as diesel combustion in an OP engine.

The piston ring pack and the ports on the cylinder linear wall have a great impact on the performance of the two-stroke opposed-piston engine. In this work, a piston ring pack model for this type of engine was generated to incorporate the exhaust ports. The effect of the exhaust ports was considered by modifying the existing friction force equation and the gas flow continuity equations. The developed model was implemented in an opposed-piston opposed-cylinder engine (a specific type of opposed-piston engine) to investigate the backpressure and the associated axial movement of all the rings of the piston ring pack under various working conditions. The results show that the gas pressure in all the regions of the piston ring pack and the axial movement of the rings are strongly affected by the exhaust ports. The gas pressure in some regions of the ring pack declines with the increase of the engine speed, while the effect of the combustion pressure (CP) on the axial movement of the ring pack can be neglected.

The supercharger technology of piston aviation engine determines its flight capabilities, and then establishes a turbocharger simulation model of an aviation piston engine. After simulating the engine ground features and 5000-meter altitude characteristics, and comparing the efficiency of compressor and turbocharger in different environments, after the installation of mechanical supercharger, gas flow has been improved, the cylinder pressure decreased about 10% compared with ground condition and engine altitude state power is restored, even 20,000 feet Power restored to 80%, which can meet the needs of high-altitude flight.

Heavy-duty vehicles, currently the second largest source of fuel consumption and carbon emissions are projected to be fastest growing mode in transportation sector in future. There is a clear need to increase fuel efficiency and lower emissions for these engines. The Achates Power Opposed-Piston Engine has the potential to address this growing need. In this paper, results are presented for a 9.8L three-cylinder OP Engine that shows the potential of achieving 55% brake thermal efficiency (BTE), while simultaneously satisfying emission targets for tail pipe emissions. The Achates Power OP Engines are inherently 20% more cost effective. The OP Engine architecture can meet this performance without the use of waste heat recovery systems or turbo-compounding and hence is the most cost effective technology to deliver this level of fuel efficiency.

The power of engine can be recovered at high altitude by matching turbocharger, however, if the mass flow of turbine is not accurate, it will result in under power or boost pressure exceed engine required strength of structure, therefore the mass flow of turbine should be regulated exact. A certain type of piston aircraft engine was selected as a testing engine and its two-stage turbo charger model was built based on GT-Power software and the model's effectiveness was demonstrated by a large number of experiments. The regulating law of turbine waste-gate in different operating conditions can be researched by using this model. The results show that the power and the intake air pressure of the engine can be achieved to the design goal within an altitude of 10,000 meters. The regulating law of the turbine waste-gate is the basis for Turbine Control Unit, which is fairly important for the development of piston aircraft engine.

SYNOPSIS.— Description of 500-H.P. vertical, 4-cylinder engine built by the Mclntosh & Seymour Corporation under license from the Swedish Diesel Engine Co.