Introduction of Technical Research Institute

The technical research institute was launch in 1968 with the foundation of Kyungwon Machinery. It successfully developed the first domestic reciprocating compressor in 1969, By developing the first screw airend, a core part of the screw compressor, through technical affiliation with SRM of Sweden in 1986, the institute introduced a completely domestic screw compressor for the first time.

As Kyungwon Machinery was split off from Century as a professional air compressor company in 2001, the institute was developed. into an annexed. research institute of Kyungwon Machinery that possesses research personnel corresponding to 159, of overall members, In 2004, the Institute succeeded in development and commercialization of the third oil-free scroll airend in the world, first in the nation.

Research activities of the institute were continue., and the institute independently developed rotor profile, a source technology of screw compressor, in 2008 to obtain domestic and overseas patents for the latest 5th generation "a" profile. This allows. COAIRE Machinery to become a leader of domestic air compressor industry, both in name and reality.

Technical research institute of Kyungwon Machinery is ceaselessly conducting research and development to secure core technologies to Iead the future compressor market, It pursues perfect product development using 5-step quality verification system including analysis of product needs, development, design, manufacture and testing.

Composition and major tasks of technical research institute


▶︎ Fields of Research

Oil-free Screw Compressor
Oil-free Scroll Compressor
Oil-free Reciprocating Compressor.
Oil flooded Reciprocating Compressor

▶︎ Fields of business

Package Design
Flow Simulation
Heat Transfer Analysis
Noise & Vibration Analysis
Oil-free Air System & Solution
Main Part Reliability Analysis


▶︎ Fields of Research

Oil flood. Screw Compressor

▶︎ Fields of business

Flow Simulation & Heat Transfer Analysis
Cooling air / Fan Test
Pre. separation simulation
Oil thermal stability Test
Heat Exchanger Selection
Compressor Valve Parts
Noise & Vibration Analysis
Oil injection Air System & Solution
Main Part Reliability Analysis


▶︎ Fields of Research

Screw Air-end
Scroll Air-end
Reciprocating Air-end

▶︎ Fields of business

Screw Rotor Profile
Scroll Wrap
Profile Cutter
Sealing System
Air-end Lubrication System
Performance Test


▶︎ Fields of Research

Compressor Control Logic & Electric Part

▶︎ Fields of business

Compressor Controller
Compressor System & Management
Compressor System Control
Compressor Air Demand Analysis
Electric Part Reliability Analysis

Major Performances of COAIRE Technical Research Institute

1970Developed the nation's first reciprocating air compressor [oil-free, oil-flooded]
1986Developed and released the nation's first screw air compressor through technical affiliation with SRM, Sweden
1990Developed scroll gas compressor and 2-stage screw gas compressor
Received IR52 Jang Young Shil Award
2001Constructed annexed research institute of Kyungwon Machinery
2004Developed the nation's first oil free scroll air compressor [3rd in the world]
2007Developed and released screw & scroll package TA5 series
2010Developed 2-step high pressure screw air compressor [20bar, as a project of small and medium Business Administration]
Oil free scroll compossor- Obtained ISO 8573-1 Class "0" Certification
2011Developed and released screw & scroll package NEW series
2011Registered domestic and overseas patents for screw profile named "α" profile
2011Developed scroll air compressor for electric buses
2013Developed the nation's first 30bar high pressure screw air compressor for starting ship engines

Possessed facilities and programs

Possessed Facilities

◦ Laboratory at research institute
◦ Screw Dynamo Tester
◦ Scroll Dynamo Tester
◦ Large Screw Test Unit
◦ Basic Performance Tester [SCREW, SCROLL, RECIPROCATING]


◦ AutoCAD
◦ Solid-works
◦ Autodesk Simulation Mechanical
◦ Autodesk Simulation CFD
◦ Screw Rotor Profile Design Program
◦ Scroll Profile Design Program
◦ Cutter Design Program
◦ Gear Design ProgramEtc

History of Screw Compressor (Air End)

The principle was established by Mr. Krigar of Germany in 1878. It was first commercialized by SRM of Sweden in 1934. In our nation, Kyungwon Machinery began asembly production in 1980s, Screw compressor product was first launched in Korea during 1986 according to exclusive tehnical agreement with SRM of Sweden. Kyungwon is contributing to reinforcement of international competitiveness and development of peripheral devices based on improvement in domestic technology,

  • Idea on the basic principle of compressor was registered as patent by Mr. Krigar of Germany
Early 1930s
  • SRM (name of the company at the time was 'The Ljungstroem Steam Trubine Co.') was Conducting an experiment on gas turbine. SRM began to develop a new compressor due to surging phenomenon experienced in centrifugal & axial flow type compressors in the past.
  • As a result of .ntinued research on the problems, Mr. All Lynsholm (Chief Engineer of SRM) of Sweden succeeded in development of positive-displacement rotary cornpressor nam. "Lysholm Compressor,That is, a dry-running screw compressor that can obtain compression ratio above 2:1 with Iwo rotors of helical lobe and groove, and one stage)
1935 ~ 1945
  • ◦ SRM conducted manufacturing on 70 screw compressors
         -Rotor diameter: 50~530mm
        -Combination of rotor lobe: 3x3, 3x4, 4x6, 5x7

    ◦ Basic theory on dry-running screw compressor was established and design parameters were determined
    ◦ Female rotor groove was the asymmetric type
    ◦ Despite the WorldWar II, SRM sign. the license agreement with several companies on this compressor type ("Lysholm Compressor")
    ◦ Early pilot products were successful, but it was difficult to satisfy the degree of precision required for processing of rotors to guarantee trouble-free operation. The compressors were determined to be not practical, and development of screw airend was temporarily terminated by the WorldWar II.
  • After the WorldWar II, research on rotor profile was continued to develop "Circular Symmetric Profile' (by Mr Hans Nilsson / Chief Engineer of SRM at the time who became president later on)
1947 ~ 1950
  • ◦ 25 compressors (rotor diameter: 110~400mm, lobe combination: 3x4, 3x5, 4x4, 5x7, 4x6) were manufactured a. tested to determine performance and characteristics of the dry compressor having 'Symmetric Circular Profile'
    ◦ SRM presented many reports in 1951 based on the result of the above test.
         1. Report 839/K-74: "Calculation of the characteristics of the screw compressor
         2. Report 841/K-75: 'Standardization of screw compressor"
         3. Report 847/K-80 'Regarding available tooling machines (American & European)
    for the manufacture of rotors for a screw compressor.
  • ◦ SRM additionally introduced standard size compressor (SRM Report 877/K-94)
        -Diameter of 6 rotors: 63, 100, 250, 400, 630
        -Lobo combination: 4x6
        -The ratio of length to diameter: 0.9, 1.5
    ◦ J. Hoiroyd & Co. develop. rotor milling machine and supplied it to HowdenCanpany of England (dias. 125, 160, 200 a. 250mm f0r processing)
    ◦ Howden greatly contributed to the development of oil flooded compressor with SRM later on.
    ◦ GHH-RAND start to manufacture SF type screw airend. (oil-free type in early stage) through technical affiliation with SRM
  • 11 companies participated in 'Technical Compressor Conference' held at SRM. AI this conference, 4x6 standard profile (diameter of two rotors is identical) developed by SRM was acknowledged as the most widely applicable compressor in the world As another surprising fact, several dry screw compressors (dia. 500mm) developed in 1950 and supplied to Municipal Gas Works in Stockholm, Sweden in 1952 have been in continuous use for 33 years unti11985. These compressors were never slopped except for two times for replacement of synchronizing gear and sleeve bearing.
1953 ~ 1958
  • Companies that signed a license agreement with SRM manufacturer. about 600 symmetric profile dry screw compressors (dia. 65~30mm) for static air compression.
  • Oil injected Prototype of SRM (performance improved by 8~10% compared to oil-free type)
  • ◦ As dry compressor began to penetrate into the market, R&D store of SRM started to develop oil inj.tion screw compressor. Al this time, the screw was used in simple or multi-stage dry gas compressor for city gas and chemical industry. ◦ With, development oil injection type air screw that showed great improvement in performance (increased sealing and cooling effects from oil), the sound level was extremely reduced compared to early dry compressors. Primary compression provided for compression up to 7~0 bar and oil injection screw compressor was used for new purposes.
  • Lightweight design for aircraft was introduced and 425 compressors were manufactured between 1956~1958.
  • The first commercialized oil injection type compressor was introduced by ATLAS COPCO.
  • Oil injection screw was used in the portable air compressors
  • Renowned air compressor makers around the world signed a license agreement with SRM
  • ◦ Oil injection screw compressor was first applied to refrigeration.
    ◦ With an attempt to develop an oil injection screw compressor used in refrigeration, "slide valve" that can perform stepless capacity control was installed on the compressor. Several companies in the refrigeration field entered into license agreement with SRM, producing about 1,000 refrigeration screw compressors.
Early 1965
  • ◦ More than 10,000 oil injection air compressors were manufactured.
Late 1965
  • ◦ Mr Lars Schibbye (Chief Engineer of SRM in 195) developed asymmetric rotor profile, and a commercialized Product was Introduced by SULLAIR of the United States in 1969.
    ◦ SRM developed an asymmetric profile targeting stationary air compressor market (Which does not have the defect of Lysholm asymmetrical profile abolished by the end of the 1940s)
    ◦ Specific power consumption was reduced by 10~ 5% compared to the symmetric profile.
    ◦ Screw compressor appeared in r.ipr.along compressor market that had been dominating the market until the 1960s.
  • ◦ Demand for small sized screw compressor(dua 63~27mm) with SRM asymmetric profile continued to increase.
    ◦ GHH-RAND developed CF type airend (5x6 profile, asymmetric, a different diameter of two rotors)
  • ◦ SRM introduced D-PROFILE.
    D profile does not refer to a specific profile but indicates an optimized method of determining the profile for different systems. It was introduced in software form to develop more than 400 D profiles.
  • ◦ Various screw profiles were developed and announced
    (SRM 'D-1982 Comp Air - 1984., Rinders - 1987 started manufacture of screw compressor)
  • Kyungwon Machinery signed an exclusive license agreement with SRM and, "started domestic production of the screw compressor"
1990 ~ 2000
  • G-profile and H-profile systems were developed by improving the disadvantages of D-profile with the development of processing technology.
2001 ~ 2012
  • Patent for "⍺" profile was registered - domestic patent in 2011 (10-1012291) and US patent in 2012 (12/328, 295)

History of Scroll Compressor (Air End)

The concept of scroll compressor was first proposed by Leon Creux of France in 1905, but it was not commercialized at the time due to lack of processing technology and measure on the gas leak.
In Korea, Kyungwon Machinery started assembly production in 1993 and successfully developed a commercial oil-free scroll air compressor for the second time. a nation and third time as a maker in October 2004, It has become an oil-free scroll air compressor manufacturer with high added value,

  • It was processed and developed by HITACHI of Japan, and commercialization was done as an air conditioner for cars by Sanden of Japan in 1981.
  • After successful commercialization by HITACHI of Japan as a home package air conditioner, COPELAND of the United States commercialized the product to vitalize scroll compressor market.
  • ◦ Japan began development of oil-free air compressor, but actual commercialization was delayed.
    ◦ Delay in commercialization was caused by lack of technology to effective, resolve axial gas leak in turning scroll, wear loss between scroll wraps, and accurate processing of scroll shape.
  • ◦ ANEST-IWATA and HITACHI of Japan succeeded in the commercialization of oil-free scroll air compressor. Higher level cam processing technology and Sealing technology were applied compared to air conditioning scroll refrigerant compressor developed in the 1980s.
    ◦ Major air compressor manufacturers in the United States and Europe recently attempted to develop oil-free scroll air compressor, but they failed to commercialize it due to patent technology of ANEST-WATA and HITACHI.
  • ◦ Kyungwon was the second as a nation and third as a maker to develop and commercialize oil-free scroll air compressor. It has become an oil-free scroll air compressor manufacturer with high added value.
    ◦ Oil free scroll air compressor exhibited high efficiency, low noise, small size a. lightweight. It was commercialized in the range of 1.5kW ~ 30kW and is widely used in diverse fields.
    ◦ In the future, efforts for development of large capacity technology are expected.
  • ◦ Obtain. ISO 8573-1: 2010 Class 0 certification
    As a certification on contaminants and purity level of compressed air, the 2010 revision reflected dust on contaminants to define Class 0 as the cleanest air.
  • ◦ Obtained CE certificate
    Attachment of CE mark on a product means that the product or its manufacturer satisfies essential requirements in the relevant regulations or directives of the EC Board of Directors. In other words, conformity lest was performed on the product by the manufacturer, importer or a third party (certification authority) for distribution of the product in the market without limits. Accordingly, products related to the health of consumers, safely and environment are obligated. to attach CE mark.Marked products can be distributed freely without inspection or testing in EU and EFTA regions.
    That is, it is a unified product certification mark acknowledged by EU and EFTA nations (members of the European Union and European Free Trade Agreement).

Operating principle of scroll air compressor

Fixed scroll and turning scroll in the operating part are combined by turning the phase of both warps by 180°. Turning scroll turns along the rotation of the crank axis as shown in the figure, Suction compression and discharge are performed simultaneously, and four enclosed spaces (compression rooms) with the shape of the crescent moon are formed

Enclosed volume of space in shape of crescent moon is gradually compressed. compressed air moves to the centre and is discharged out through outlet at the centre of the fixed scroll

Structure of scroll air compressor

Characteristics of scroll air compressor

High efficiency during compression process through prevention of gas leak

◦ Since pressure difference between two compression pockets of fixed and turning scrolls is smaller than overall pressure difference calculated by subtracting suction pressure from discharge pressure. compared gas is never recompressed. This results in smaller power loss compared to other compressors.
◦ In the case of reciprocating compare and rolling piston compressor, the recompression process is repeated to reduce the efficiency of the compressor

Suction compression and discharge are continuously performed.

◦ It involves low vibration and noise as compression is continuously performed with a slower speed of pressure increase compared to other compressors.
◦ Change in torque of scroll compressor is about 1/10 of torque change shown by other the compressors, exhibiting a significant reduction in vibration and noise1.
◦ Rotation and compression torque of the crank axis (figure on the right)

Suction valve and discharge valve are unnecessary

◦ Since suction room inhaling gas and discharge room performing discharge are not directly connected, suction and discharge valves are unnecessary. As a result, there are no problems related to fluid loss. noise and damaging. The product obtained high efficiency, low noise and high reliability.

Advantages of oil-free air compressor

◦ It supplies clean air.
◦ It is appropriate for the purpose as described below as compressed air does not include oil mist.
   -food manufacturing machinery, beverage manufacturing machinery, medical device. a dental device, analyzer chemical industry, chemical industry, particulate return, painting. printing machinery. paper processing, water quality improvement
◦ Oil management such as oiling unnecessary
   - Oil management such as routine oiling is unnecessary, and there is no cost for oil replacement and filling.
◦ Excellent environmental protection (no oil mist)
  -Since oil mist is not discharged, the surrounding environment is not polluted.
◦ Oil mist filter does not need to be installed and managed.
  - Costs for installation and element replacement of oil mist removal filter are unnecessary.
◦ There is no cost for treatment of waste oil.
  - No industrial waste and wastewater is generated.
  - There is no cost that occurs to industrial waste management business.
◦ here is no cost for management of drain.
   - Oil injection drain contains oil in water and involves a cost for wastewater treatment. but oil-free type does not have such cost.
◦ Pressure loss from contamination on the interior of the pipe is low.
  - When used for a long time. contaminants inside the pipe can be increased to cause pressure loss and failure of devices such as auto trap, increasing the cost burden compared to the initial electric charge.
◦ Simple air circuit compared to forced oil injection circuit
  - Low failure rate