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Port, Valve, Intake, and Exhaust System Design
Published in John B. Heywood, Eran Sher, The Two-Stroke Cycle Engine, 2017
The most commonly used two-stroke engine configuration is fixed scavenge and exhaust ports in the cylinder liner that are opened and closed by the moving piston [arrangement (a) in Fig. 5-1]. The important characteristics of the gas exchange process are the removal of the burned gas from the cylinder at the end of the power stroke, the effectiveness of the charging processes, and the composition of the in-cylinder charge and its spatial distribution. These depend to a large extent on the geometry and layout of the ports, as well as engine operating conditions. A cylinder port system is characterized by the crank angle at which each port opens, the size, geometry, and number of ports, their location around the cylinder liner circumference, and the geometrical shape of the gas passage, which determines the direction and flow pattern of the jet issuing from the port into the cylinder with scavenging ports or out of the cylinder with the exhaust port. Scavenge ports are usually inclined in the axial or in the transverse plane or in both. This is done to direct the flow into the cylinder so as to achieve the desired in-cylinder scavenging process. In the uniflow scavenging system, the scavenge ports are inclined 15–60° relative to the radial direction to make the incoming charge swirl around the cylinder axis. Ports are usually rectangular, with rounding of the comers. This shape provides the largest available flow for a given bridge width. The common port shapes are shown in Fig. 5-14.
Internal Combustion Engines
Published in Don M. Pirro, Martin Webster, Ekkehard Daschner, Lubrication Fundamentals, 2017
Don M. Pirro, Martin Webster, Ekkehard Daschner
Most four-cycle engines are equipped with poppet valves in the cylinder head for both intake and exhaust. Various arrangements are used to operate these valves. In the conventional arrangement, a camshaft is located along the side or center of the cylinder block depending on engine configuration. It is driven from the crankshaft by gears, a silent chain, or in some engines by a toothed belt. Roller-, solid-, or hydraulic-type cam followers (often called valve lifters) ride on the cams and operate push rods, which in turn operate the rocker arms to open the valves. Valve closing is accomplished by springs surrounding the valve stems. This type of arrangement can result in some mechanical lag in valve operation at high speeds; thus, some high-speed automotive engines have the camshafts located above the cylinder head so that the valve stems bear directly on the cams or on short rocker arms. This arrangement is called overhead camshaft construction. The cam drive for many of these uses a chain or a toothed rubber belt, but a few designs incorporate gear drives for the overhead cams. Some large, medium, and low-speed diesel engines now are equipped for direct operation of the valves in a somewhat similar manner, and fully hydraulic valve actuation is also used on a few engines. The complete valve operating mechanism is often referred to as the valve train.
Generator Driver Applications and Selection
Published in Neil Petchers, Combined Heating, Cooling & Power Handbook: Technologies & Applications, 2020
These results show that, as expected, the reduction in process hot water load will have a greater impact on the reciprocating engine configuration than on the gas turbine configuration. As such, under these site-specific conditions, the gas turbine system now shows superior economic performance.
The effect of engine spin direction on the dynamics of powered two wheelers
Published in Vehicle System Dynamics, 2018
Matteo Massaro, Edoardo Marconi
Steady turning is analysed in order to evaluate the effect of the two configurations on the vehicle trim, namely on the equilibrium roll angle. Eigenvalue analysis is performed in order to evaluate the effect of engine configuration on vibration modes, namely on weave and wobble. Limit acceleration and limit braking manoeuvres are analysed in order to asses the effect of spin direction on the vehicle performance. Lane change manoeuvres are simulated in order to estimate the effect of the engine configuration on handling.