Linear alternator

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A linear alternator is essentially a linear motor used as an electrical generator.

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An alternator is a type of alternating current (AC) electrical generator. The devices are often physically equivalent. The principal difference is in how they are used and which direction the energy flows. An alternator converts mechanical energy to electrical energy, whereas a motor converts electrical energy to mechanical energy. Like many electric motors and electric generators, the linear alternator works by the principle of electromagnetic induction. However, most alternators work with rotary motion, whereas linear alternators work with linear motion (i.e. motion in a straight line).

Theory

A linear alternator is most commonly used to convert back-and-forth motion directly into electrical energy. This eliminates the need for a crank or linkage to convert a reciprocating motion to a rotary motion in order to drive a rotary generator. [1]

Air compression generator

Mainspring Energy's linear generator is a Homogeneous Charge Compression Ignition (HCCI) - a form of internal combustion in which well-mixed fuel and oxidizer (typically air) are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction produces heat that can be transformed into work in a heat engine. It is compatible with various fuels, including ammonia, and biogas, and hydrogen. The commercial device is double-ended piston that relies on a precise mixture of fuel and air and a predetermined compression to effect the charge of fuel and air to self combust. A translator is connected to the piston with a fixed rod to the piston, the translator providing the energy to compress the fuel air homogeneous charge then absorb the resulting energy from the expansion of combustion gases on each end. As the translator moves back and forth past permanent magnets providing both the control of compression needed to assure ignition occurs at or near top dead center while generating electricity. Stationary copper coils surround each translator, forming a linear electromagnetic machine (LEM). Air and fuel are introduced into the center reaction chamber. Energy stored in the air springs from a previous cycle compresses the mixture until a flameless, exothermic reaction otherwise known as combustion [2] occurs. The reaction pushes the translators back through the copper coils, producing electricity. This motion recompresses the air springs, readying the system for the next cycle. Byproducts are water, nitrogen gas, and other substances. The reaction requires no spark/ignition source. A 115 kW machine extends 5.5 meters and is about 1 meter in diameter. [3]

Applications

The simplest type of linear alternator is the mechanically powered flashlight (shake type). This is a torch (UK) or flashlight (USA) which contains a coil and a permanent magnet. When the appliance is shaken back and forth, the magnet oscillates through the coil and induces an electric current. This current is used to charge a capacitor, thus storing energy for later use. The appliance can then produce light, typically from a light-emitting diode, until the capacitor is discharged. It can then be re-charged by further shaking. Because of this, they are sometimes referred to as a faraday flashlight.

Other devices that use linear alternators to generate electricity include the free-piston linear generator, an internal combustion engine, and the free-piston Stirling engine, an external combustion engine.

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<span class="mw-page-title-main">Electric generator</span> Device that converts other energy to electrical energy

In electricity generation, a generator is a device that converts motion-based power or fuel-based power into electric power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, wind turbines and even hand cranks. The first electromagnetic generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday. Generators provide nearly all the power for electrical grids.

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  2. Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage.
  3. Combustion: Also known as power or ignition. This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution. While the piston is at T.D.C. the compressed air-fuel mixture is ignited by a spark plug or by heat generated by high compression, forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft.
  4. Exhaust: Also known as outlet. During the exhaust stroke, the piston, once again, returns from B.D.C. to T.D.C. while the exhaust valve is open. This action expels the spent air-fuel mixture through the exhaust port.
<span class="mw-page-title-main">Alternator</span> Device converting mechanical into electrical energy

An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature. Occasionally, a linear alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, but usually, the term refers to small rotating machines driven by automotive and other internal combustion engines.

Dieseling or engine run-on is a condition that can occur in spark-plug-ignited, gasoline-powered internal combustion engines, whereby the engine keeps running for a short period after being turned off, drawing fuel through the carburetor, into the engine and igniting it without a spark.

<span class="mw-page-title-main">Pneumatic motor</span> Compressed-air engine

A pneumatic motor, or compressed-air engine, is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed-air energy to mechanical work through either linear or rotary motion. Linear motion can come from either a diaphragm or piston actuator, while rotary motion is supplied by either a vane type air motor, piston air motor, air turbine or gear type motor.

<span class="mw-page-title-main">Otto engine</span> Large stationary single-cylinder internal combustion four-stroke engine

The Otto engine is a large stationary single-cylinder internal combustion four-stroke engine, designed by the German Nicolaus Otto. It was a low-RPM machine, and only fired every other stroke due to the Otto cycle, also designed by Otto.

Homogeneous Charge Compression Ignition (HCCI) is a form of internal combustion in which well-mixed fuel and oxidizer are compressed to the point of auto-ignition. As in other forms of combustion, this exothermic reaction produces heat that can be transformed into work in a heat engine.

<span class="mw-page-title-main">Timeline of heat engine technology</span>

This timeline of heat engine technology describes how heat engines have been known since antiquity but have been made into increasingly useful devices since the 17th century as a better understanding of the processes involved was gained. A heat engine is any system that converts heat to mechanical energy, which can then be used to do mechanical work.They continue to be developed today.

<span class="mw-page-title-main">Hot-bulb engine</span> Internal combustion engine

The hot-bulb engine, also known as a semi-diesel, is a type of internal combustion engine in which fuel ignites by coming in contact with a red-hot metal surface inside a bulb, followed by the introduction of air (oxygen) compressed into the hot-bulb chamber by the rising piston. There is some ignition when the fuel is introduced, but it quickly uses up the available oxygen in the bulb. Vigorous ignition takes place only when sufficient oxygen is supplied to the hot-bulb chamber on the compression stroke of the engine.

<span class="mw-page-title-main">Dynamo</span> Electrical generator that produces direct current with the use of a commutator

A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter.

<span class="mw-page-title-main">Free-piston engine</span> Type of engine with no crank

A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device and a load device.

<span class="mw-page-title-main">Magneto</span> Electricity-producing machine

A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, although it is usually considered distinct from most other alternators, which use field coils rather than permanent magnets.

<span class="mw-page-title-main">Alternator (automotive)</span> Devices in automobiles to charge the battery and power the electrical system

An alternator is a type of electric generator used in modern automobiles to charge the battery and to power the electrical system when its engine is running.

<span class="mw-page-title-main">Internal combustion engine</span> Engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance. This process transforms chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.

The free-piston linear generator (FPLG) uses chemical energy from fuel to drive magnets through a stator and converts this linear motion into electric energy. Because of its versatility, low weight and high efficiency, it can be used in a wide range of applications, although it is of special interest to the mobility industry as range extenders for electric vehicles.

In engineering, a solenoid is a device that converts electrical energy to mechanical energy, using an electromagnet formed from a coil of wire. The device creates a magnetic field from electric current, and uses the magnetic field to create linear motion.

References

  1. ↑ Baker, David R. (18 April 2023). "How to Sell a Power Generator No One Has Heard Of". Bloomberg Green . Retrieved 19 April 2023.
  2. ↑ "Homogeneous charge compression ignition". August 19, 2024 – via Wikipedia.
  3. ↑ Svrcek, Matt (March 2023). "The Omnivorous Generator: Mainspring's Linear Generator can Run on Almost any Fuel". IEEE Spectrum. 60 (3): 34–46. doi:10.1109/MSPEC.2023.10061630. ISSN   1939-9340.
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