Engine Balancing Quiz

Forces arising from the acceleration of reciprocating masses in an engine.

The component of inertial force that varies proportionally to the crankshaft speed. It changes direction twice per revolution.

The component of inertial force that varies at twice the crankshaft speed. It changes direction four times per revolution.

The phenomenon of representing inertial forces as rotating vectors for easier analysis, similar to how centrifugal forces are represented.

The balancing of forces from different reciprocating masses in a multi-cylinder engine.

A type of engine where the piston completes a full cycle in four strokes: intake, compression, power, and exhaust.

The cyclical variation in crankshaft torque caused by the reciprocating masses of the engine.

An engine configuration where the cylinders are arranged in a V-shape. This configuration can lead to uneven inertial forces compared to inline engines.

In an inline engine with evenly spaced cranks, the torque vectors add up when the harmonic is a multiple of i/2 and cancel each other out when it's not. This is due to the phasing of the cylinders.

For multi-cylinder engines, the total torque can be calculated by summing the contributions of each cylinder's torque for each harmonic.

The force acting on a rotating mass due to its rotation, determined by the mass, angular velocity squared, and the radius of rotation.

A diagram that shows the positions of pistons in an engine at different crank angles, helping visualize the balance or imbalance of centrifugal forces.

In certain engine configurations, the centrifugal forces created by rotating components cancel each other out due to their placement and movement.

The order in which cylinders fire in a multi-cylinder engine, impacting engine smoothness and vibration.

The arrangement of crankshaft throws in a multi-cylinder engine, determining the relative positions of pistons and firing order.

A combustion cycle where the intake valve is closed before the piston reaches bottom dead center (BDC), increasing efficiency by expanding the air charge before compression.

A combustion cycle where the intake valve is closed after the piston has reached BDC, increasing efficiency by pushing some air back into the intake manifold.

A thermodynamic cycle used in large diesel engines and some niche automotive applications, which achieves higher efficiency by employing either EIVC or LIVC.

A thermodynamic cycle where the working fluid changes its chemical composition during the combustion process.

During the intake and compression phases of an air-fuel cycle, the mixture of air and fuel remains relatively unchanged, behaving like a frozen mixture.

The ability of a cycle to convert heat energy into useful work, expressed as a percentage.

The process of a working fluid expanding at a constant entropy, typically used in engines.

A cycle where heat is rejected from the working fluid at a constant temperature.

A cycle where the working fluid is expanded at constant pressure.

The Otto cycle is a theoretical cycle where the combustion process is instantaneous and ideal, leading to high pressures.

The ratio of the volume of the working fluid at the start of the compression stroke to the volume at the end of the compression stroke.

The maximum pressure reached within the cycle, typically after combustion.

A measure of the average pressure acting on the piston during the power stroke, determining the engine's power output.

The process where combustion products at high temperatures decompose back into their original reactants due to high thermal energy.

The opposite of dissociation, where combustion products recombine as they cool down, but not fully recovering the lost energy.

The ratio of the efficiency of a Miller cycle engine (with variable valve timing) to the efficiency of an Otto cycle engine (traditional fixed timing) at the same operating conditions.

The ratio of the mean effective pressure (imep) of a Miller cycle engine to the imep of an Otto cycle engine at the same operating conditions.

An engine cycle where the intake and exhaust phases are idealized as instantaneous valve events at Top Dead Center (TDC) and Bottom Dead Center (BDC), with no volume change during valve opening and closing.

The change in pressure within the cylinder during intake and exhaust, assuming the external pressure is not equal to the cylinder pressure, resulting in fresh charge or burned gas flowing to equalize the pressures.

The process of controlling an engine's power by adjusting the pressure in the intake manifold.

An engine where the intake manifold pressure is higher than the atmospheric pressure, leading to increased power.

The ratio of the work obtained from the engine to the lower heating value of the fuel consumed.

The slope of the tangent line to a thermodynamic process curve at a specific point.

A key factor affecting air-fuel cycle efficiency due to the varying energy content of gases at different temperatures.

The change in the number of moles and molar mass of the gas mixture before and after combustion.

A thermodynamic cycle where the working fluid remains unchanged during the cycle.