What is a Flywheel?
A flywheel is a common machine component, capable of storing rotational energy for later use. When the machine reaches a point where the supply power is inefficient for operations, the flywheel will release its stored energy. Within a standard internal combustion engine, for example, the fluctuating torque produced by the crankshaft during a complete cycle will cause the shaft to have a change in its angular velocity. Through the implementation of a flywheel, inertia mass is provided at the end of the shaft so that the torque will become more balanced.
For an engine that follows the four-stroke process of combustion, two complete revolutions of the crankshaft will result in a single power stroke for each cylinder. As the power stroke is conducted, the flywheel will retain kinetic energy to use later during intake and compression strokes for the means of creating uniform operations. It is important that the flywheel is present and functional within the engine, lest the crankshaft pulsates which will cause the engine to quickly reach a stop as strokes become intermittent and longer. When utilizing a flywheel for such applications, the assembly must be dynamically balanced so that vibration is mitigated for the benefit of the crankshaft and bearing.
When an energy level that exceeds the supply is required for an application, a flywheel may be used to furnish intermittent pulses of energy to a system. In order to achieve such operations, the flywheel will be attached to the power source and will slowly build up energy over time. When extra energy is required by the system, the flywheel will then begin releasing its storage at a high rate so that the supplied power exceeds the source. This method of operations is very beneficial for machinery or equipment such as power hammers and riveting machines.
Rather than store and supply energy, flywheels may also serve as a means to manage direction and prevent unwanted motion. Depending on their implementation, the flywheel may act as a gyroscope for instrumentation, a reaction wheel for ship or satellite stabilization, a friction motor for spinning toys, and more. In each instance, the flywheel will often come in special types that specifically aid the system or machine they are placed within.
Flywheels also have the capability of producing or sinking reacting power, rather than having a direct influence on real power. As such, the flywheel will operate as an electric compensator so that it may adjust a grid voltage or benefit the power factor of a system. When acting as an electric compensator, the flywheel may be comparable to that of a synchronous motor.
When procuring a flywheel, it is important to consider the material needed for an application. Generally, the flywheels present within engines and vehicles will be produced from cast iron, nodular iron, steel, or aluminum. Meanwhile, less intensive applications may take advantage of lead or cast iron. Across all applications, it is important that the flywheel is capable of taking on high tensile loads for storing energy, ensuring that the piece does not break apart.