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Opposed-piston (OP) engines have attracted the interest of the automotive industry in recent years because of their potential for significantly improved fuel economy. Opposedpiston, two-stroke (OP2S) engine technology amplifies this fuel efficiency advantage and offers lower cost and weight due to fewer parts. While OP engines can help automotive manufacturers comply with current, and future, efficiency standards, there is still work required to prepare the engines for production. This work is mainly related to packaging and durability. At Achates Power, the OP2S technology is being developed for various applications such as commercial vehicles (heavyand medium-duty), SUVs, pick-up trucks and passenger cars (i.e. light-duty), military vehicles, large ships and stationary power (generator sets). Included in this paper is a review of the previously published OP engine efficiency advantages (thermodynamics, combustion and air system) as well as the architecture's historical challenges. Also included is: 1. An overview of the packaging-related challenges of OP2S engines using opportunities with the dual-crank, Junkers Jumo-style design with power take-out options, vertical engine installation and bore-to-bore distance. 2. Different design parameters of the OP2S engine and their optimization for various applications. 3. Details of OP2S engines for various applications, including packaging concepts and performance and emissions results. These results suggest that the technology is ready to produce an economically and environmentally sustainable OP powertrain-one that is clean, fuel efficient and can fit into existing vehicles, be manufactured in today's engine plants, and run on a variety of fuels.

The piston stopping position directly impacts the next engine starting after engine flameout in idle stop system. The shutdown process of the gasoline direct injection (GDI) engine is studied by theory analysis and simulation experiments. The both mathematical model of the cylinder gas and crankshaft output torque are derived. The bench test system is designed for the GDI engine. By comparing the simulation and bench experiment, the torque and speed characteristics of the shutdown process are analyzed. The conclusion is derived that the distribution of the piston stopping at 60-80°CA before upper dead center is about 90%. The results show that the torque changes are approximate cycle attenuation process without considering the air leakage and other perturbation.

For the opposed-piston and opposed-cylinder (OPOC) diesel engine with higher power density, recently it has drawn even more attentions than ever in several developed countries, such USA and Germany, et al, which is regarded as a technical innovation to further reduce emission, and decrease fuel consumption, attributed to outstanding thermal efficiency and engine package downsizing. To explore the interrelation of this special crank system in concept design stage, the multi-body dynamics and durability of the piston-opposed crankshaft system was investigated. Firstly the optimized function model of the unique crankshaft system in an OP2S (Opposed-piston two stroke) engine was established. Then it was to figure out the influence of all structural design parameters on OPE crankshaft averaged output torque, respectively. The calculated results show that the initial crank angle difference between inner crank web and outer crank web was the most critical contributor to elevate the averaged torque output than other structural parameters. The parametric 3D model of crankshaft system was refreshed automatically based on the optimized variables. Finally an OPE crankshaft prototype was manufactured and bend fatigue experiment was carried out in a relevant laboratory to obtain the material S-N Curve. The HCF (High Cycle Fatigue) result was indicated that the minimum safety factor on crank journal fillets can reach relevant estimation criterion without crankshaft failure occurring for an engine speed sweep.

The cooling system design for a two-stroke, opposed-piston (OP) engine is substantially different from that of a conventional four-stroke engine as the opposed-piston engine requires efficient cooling at the center of the cylinder where the heat load is highly concentrated. A thermally efficient design ensures engine durability by preserving the oil film at the top ring reversal zone. This is achieved by limiting the surface temperature of the liner to below 270° C at this location. Various water jacket designs have been analyzed with computational fluid dynamics (CFD) using a “discretized” Nusselt number approach for the gas side heat flux prediction. With this method, heat transfer coefficients are computed locally given the flow field of the combustion gases near the liner surface and then multiplied by the local gas/liner temperature difference to generate the heat flux distribution into the cylinder liner. The heat flux is then averaged over the cycle before being applied as a boundary condition to the CFD simulation. The baseline design consists of a simple water jacket with coolant flowing axially from the inlet near the intake port to the outlet near the exhaust port. This approach yields uneven cooling both longitudinally and circumferentially about the cylinder liner. A greatly improved thermal response has been achieved by introducing the coolant at the hot center section of the liner with roughly half of the coolant flowing toward either end of the cylinder. A detailed analysis shows that liner surface temperatures well below 270° C can be achieved for an engine with a power density of 50kW/liter by carefully optimizing the coolant velocities in the center section of the liner.

Engine energy-balance and the real working-process analysis are the oldest and most validated approaches for the calculation of the engine operating cycles. Since the beginning they have accompanied the engine development processes. In the approach of the engine energy-balance, the combustion chamber, the entire engine or any other part of an internal combustion engine can be treated as an open thermodynamic system. Target of this approach is the analysis of the energy exchanges of the system through its boundaries with the surrounding system. In case of the entire engine the surrounding is represented by the environment.

This chapter analyzes the main challenges in the application of ”simulation optimization” to the design of engine components, with particular reference to the combustion chamber of a Direct Injection Diesel engine evaluated via Computational Fluid Dynamic (CFD) codes.

A new type of high-efficiency reciprocating internal combustion engine — called the “isoengine” — is being developed, which has separate cylinders for compression and combustion. The fully developed engine is predicted to generate electricity at net electrical plant efficiencies of up to 60% with unit sizes in the range of about 5–20 MWe . The specific capital cost and overall engine size are expected to be similar to those of conventional large engines. The construction of a first 3 MW prototype engine has now been fully completed and in October 2002 the first fuel was injected. The present paper focuses on the experience and test results obtained during the commissioning and early test stage of the prototype engine. The testing of this Engineering Demonstrator will contribute significantly to the development of a Commercial Demonstrator and first commercial isoengines, which should be available in the second half of this decade. NOTE: This paper was presented at the ASME 2003 Internal Combustion Engine Division Spring Technical Conference but was printed in the ASME 2003 Internal Combustion Engine and Rail Transportation Divisions Fall Technical Conference proceedings, pages 409–418. It should appear under the Engine Design heading. Copyright © 2003 by ASME

Current general aviation light aircraft are powered by engines that were originally designed in the 1940's. This paper gives a brief history of light aircraft engine development, explaining why the air-cooled, horizontally opposed piston engine became the dominant engine for this class of aircraft. Current engines are fairly efficient, and their designs have been updated through the years, but their basic design and operational characteristics are archaic in comparison to modem engine designs, such as those used in the automotive industry. There have been some innovative engine developments, but in general they have not been commercially successful. This paper gives some insight into the reasons for this lack of success. There is now renewed interest in developing modem propulsion systems for light aircraft, in the fore-front of which is NASA's General Aviation Propulsion (GAP) program. This paper gives an overview of the engines being developed in the GAP program, what they will mean to the general aviation community, and why NASA and its industry partners believe that these new engine developments will bring about a new era in general aviation light aircraft.

This study is based on experimental test results, typical for small passenger car diesel engines. The influence of engine size on the performance of the car was investigated using four different types of engine. The four types of engine were (a) naturally aspirated engine, (b) engine with turbocharger and waste gate, (c) engine with pressure wave supercharger (PWS) and (d) engine with PWS and intercooler. The performance of the car fitted with the pressure wave supercharger ComprexR* was examined and found to have excellent response, reduced fuel consumption and reduced exhaust emissions.

A thermodynamic engine which converts heat generated by a radioisotope into mechanical energy pulses is described. The mechanical energy pulses are produced by first heating a curved bimetallic dis...

The range of piston ring materials currently available to the designer is given, showing their relative importance in durability and fatigue. Ring wall pressures for given duties illustrate the wide variations that exist. The piston ring free shape and its association with the ratings of diesel power units highlight the need for a better understanding of thermal gradients in ring section. Surface coatings and their relative merits to ring wear, scuff, and liner wear are illustrated. Oil control and blow-by characteristics from break-in to stable operation are discussed. Piston ring groove temperatures coupled with cylinder liner wall temperatures adjacent to the top ring location need early appraisal in design and development. Control of surface finish for both cylinder liner and piston ring is important for the critical break-in period. Control of quality is outlined.

This paper gives the results of air-flow tests through two-stroke cycle and four-stroke cycle diesel engine cylinder heads and ports on steady-flow low-pressure air flow rigs.An analysis is made of the pressure drop through a diesel engine cylinder head inlet port system which shows the effect of the various parts of the system on flow loss. This also includes the effects of valve lift, valve seat angle, and valve shape on isentropic area.A comparison is made between tandem and Siamese porting on a four-stroke cycle engine cylinder head. The results of tests on uniflow scavenged two-stroke cycle inlet ports and exhaust valves are also included.

Double acting Diesel engines have rapidly increased in number and output in late years in this country, owing to the idea of applying Diesel engines as only means of economical power production of large units for marine propulsion. Few reports of theoretical or experimental analysis about the piston rod of the double acting Diesel engine have been published, which would be of great value for designers and engineers. The author reports the analysis of the causes of the damage on the piston rod of the main engine of the motor ship “Kohwa Maru”, the first double acting two cycle Diesel engine adopted for ship propulsion in this country.

Little Attention was paid to the characteristics of the fuel for the early aircraft engines. They had available to them a gasoline primarily intended for automobile engines, the earliest of which used wick carburettors. These carburettors required a fuel of extremely high volatility and with the straight run gasolines available at the time, volatility could be related to specific gravity. The lower the specific gravity, the better the volatility and the requirement for low specific gravity endured for about the first twenty years of the life of the aircraft engine.

The foregoing experimental investigations have demonstrated the possibility of making a noncontact measurement of the gap between the piston and cylinder of an internal-combustion engine by fast-electron probing with unilateral access to the engine. No changes have to be made to the working parts of the engine, not do additional devices have to be inserted. The resultant absolute gap-measuring error of ±5μ in the range 10–300μ may be regarded as quite satisfactory. This error is similar to the measuring errors encountered in direct methods of gap measurement, while the range of gaps capable of being measured in this way lies in the ordinary range of practical interest (10–200μ for the most probable gap of 50–80μ); however, in the method here proposed there is no need to make special preparation of the inner working surfaces of the engine. There are no basic limitations preventing the extension of the method to gaps several millimeters wide. The method here employed may be successfully applied for the noncontact measurement of gaps between periodically-moving machine parts.

Scaling down the conventional four stroke diesel engine, to arrive at the small efficient engine needed for the economic automotive market, presents limitations, which are fundamentally better overcome by the two stroke diesel. In the truck sizes the two stroke has had many successes. General Motors in the U.S.A. and the three litre Tilling Steven opposed piston engine in the U.K. are examples. To meet the ever increasing demands on emissions and noise, however, the two stroke diesel has inherent limitations which have held back its use for the automotive application. The initial objectives of the Armstrong Whitworth Swing Beam Engine were directed towards overcoming these limitations. This engine layout was designed to create a low noise structure, arising from a balanced linkage system, other advantages of easy start and the potential use of low grade fuel derive from its variable compression ratio and slow piston motion near inner dead centre. Test results so far show that it has the potential for more advanced development. The developments in the application of ceramics to diesel engines could be a major advance for the small high output diesel engine. They are also seen as a possible major breakthrough for the opposed piston engine in two aspects: firstly because only the piston and liner will need making in ceramics--the absence of the cylinder head eliminates the difficult valve plate and port passage of the four stroke; and secondly the potential to run without piston lubrication eliminates the problem of loss of oil in the ported liner. Low piston side thrust forces of the Swing Beam engine will benefit the unlubricated ceramic liner and also lends itself to introducing the short crosshead piston and rod-seals which exclude crankcase oil from the cylinder. Ceramics will also extend the power range of this engine. Increased exhaust temperature compensate for the lower efficiency of the small turbocharger and so reduce blower power and raise thermal efficiency. Developments are going on with quiet scavenge blowers and blowers utilising the flywheel which is seen as another important breakthrough for the two stroke diesel. Servo-operated fuel systems also have been run which would give injection characteristics well suited to the (DI) O.P. engine.

Renault has just unveiled a new version of its popular R20 family sedan, fitted with an all new 2 liter, 4 cylinder in line diesel engine. It features an aluminum crankcase, a new type of cylinder liner, an aluminum cylinder head with an overhead camshaft driven by a toothed belt, a new type of swirl chamber, and a nodular cast iron crankshaft. This engine will power various passenger cars and light-duty vans in the near future. This paper describes the main design, development and performance features of the engine, as well as some special manufacturing means which were developed.