A linear compressor is a
gas compressor
A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.
Many compressors can be staged, that is, the gas is compressed several times in steps or ...
where the piston moves along a linear track to minimize friction and reduce energy loss during conversion of motion. This technology has been successfully used in cryogenic applications which must be oil-less. The suspension spring can be flexure type or coil type. An oil-free valved linear compressor enables the design of compact heat exchangers.
Linear compressors work similarly to a
solenoid
upright=1.20, An illustration of a solenoid
upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines
A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whos ...
: by using a spring-loaded piston with an electromagnet connected to AC through a diode. The spring-loaded piston is the only moving part, and it is placed in the center of the electromagnet. During the positive cycle of the AC, the diode allows energy to pass through the electromagnet, generating a magnetic field that moves the piston backwards, compressing the spring, and generating suction. During the negative cycle of the AC, the diode blocks current flow to the electromagnet, letting the spring uncompress, moving the piston forward, and compressing the refrigerant. The compressed refrigerant is then released by a valve.
History
A number of patents for linear compressors powered by
free-piston engines were issued in the 20th century, including:
* To
Brown, Boveri & Cie
Brown, Boveri & Cie. (Brown, Boveri & Company; BBC) was a Swiss group of electrical engineering companies. It was founded in Baden bei Zürich, in 1891 by Charles Eugene Lancelot Brown and Walter Boveri who worked at the Maschinenfabrik Oer ...
, GB191215963, published 1913-10-08
* To
Hugo Junkers
Hugo Junkers (3 February 1859 – 3 February 1935) was a German aircraft engineer and aircraft designer who pioneered the design of all-metal airplanes and flying wings. His company, Junkers Flugzeug- und Motorenwerke AG (Junkers Aircraft and ...
, CA245708, published 1924-12-30
* To
Raúl Pateras Pescara, US1615133, published 1927-01-18
The first market introduction of a linear compressor to compress
refrigerant
A refrigerant is a working fluid used in the cooling, heating, or reverse cooling/heating cycles of air conditioning systems and heat pumps, where they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are ...
in a
refrigerator
A refrigerator, commonly shortened to fridge, is a commercial and home appliance consisting of a thermal insulation, thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to ...
was in 2001.
Valved linear compressor
The single piston linear compressor uses dynamic counterbalancing, where an auxiliary movable mass is flexibly attached to a movable piston assembly and to the stationary compressor casing using auxiliary mechanical springs with zero vibration export at minimum electrical power and current consumed by the motor.
It is used in
cryogenic
In physics, cryogenics is the production and behaviour of materials at very low temperatures.
The 13th International Institute of Refrigeration's (IIR) International Congress of Refrigeration (held in Washington, DC in 1971) endorsed a univers ...
s.
Linear compressors are used as they have fewer mechanical losses.
Linear compressors are made by LG and used in LG and Kenmore refrigerators. Linear compressors were also announced by
Embraco. Compressors of this type have less noise, and are more energy efficient than conventional refrigerator compressors. The Embraco linear compressors are also claimed to be oil-free. In the 2010s and 2020s, multiple lawsuits in the United States alleged that the LG compressors had a high rate of failure or lack of expected cooling. As of 2024, there were settlements and ongoing cases.
See also
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Scroll compressor
References
External links
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{{HVAC
Gas compressors
Vacuum pumps
Cooling technology
Hydrogen technologies