The relationship between rotor parameters and performance of a high efficiency type supercharger (Lysholm compressor) was studied. It is necessary that. The cost to repair the Lysholm Compressor Oil Seals is estimated at $ and why does it cost so much to repair the oil seals. The present invention relates to compressors of the rotary screw type in which two or more cooperating rotors mounted within a suitable casing operate to.

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A rotary-screw compressor is a type of gas compressorsuch as an air compressor, that uses a rotary-type positive-displacement mechanism. They are commonly used to replace piston compressors where large volumes of high-pressure air are needed, either for large industrial applications or to operate high-power air tools such as jackhammers and impact wrenches.

The gas compression process of a rotary screw is a continuous sweeping motion, so there is very little pulsation or surging of flow, as occurs with piston compressors. Rotary-screw compressors use two meshing helical screws, known as rotors, to compress the gas.

In a dry-running rotary-screw compressor, timing gears ensure that the male and female rotors maintain precise alignment.

In an oil-flooded rotary-screw compressor, lubricating oil bridges the space between the rotors, both providing a hydraulic seal and transferring mechanical energy between the driving and driven rotor. Gas enters at the suction side and moves through the threads as the screws rotate.

The meshing rotors force the gas through the compressor, and the gas exits at the end of the screws. The effectiveness of this mechanism is dependent on precisely fitting clearances between the helical rotors and between the rotors and the chamber for sealing of the compression cavities.

However, some leakage is inevitable, and high rotational speeds must be used to minimize the ratio of leakage flow rate over effective flow rate. In contrast to Roots blowersscrew compressors are made with different profiles on the two rotors: Usually the male rotor has fewer lobes than the female rotor, so that it rotates faster.

Originally, screw compressors were made with symmetrical rotor cavity profiles, but modern versions use asymmetrical rotors, with the exact rotor designs being the subject of patents. For units in the 5 through 30 HP range the physical size of these units are comparable to a typical two-stage compressor. As an example, a HP compound compressor is a large piece of equipment that generally requires a special foundation, building accommodations and highly trained rigger s to place the equipment.

On the other hand, a HP rotary-screw compressor can clmpressor placed on an ordinary shop floor using a standard forklift.

Within industry, a HP rotary-screw compressor is generally considered to be a compact piece of equipment. Rotary-screw compressors are commonly available in the 5 through HP range and can produce air flows in excess of SCFM.

While there are high pressure rotary-screw compressors, within the compressed air community, the upper lysholj limit is generally around PSI. Rotary-screw compressors tend to be smooth running with limited vibration, thus not requiring a specialized foundation or mounting system. Normally, rotary-screw compressors are mounted using standard rubber isolation mounts designed to absorb high-frequency vibrations.

This is especially true in rotary-screw compressors that operate at high rotational speeds. Using CFM to rate a compressor is incorrect because it represents a flow rate that is independent of a pressure reference.

Rotary-screw compressors are generally used to supply compressed air for larger industrial applications. They are best applied in applications that have a continuous air demand such as food packaging plants and automated manufacturing systems. In larger facilities, that may have only intermittent applications, the average usage among the many work stations will place a continuous demand on the compressor.


In addition to fixed units, rotary-screw compressors are commonly mounted on tow-behind trailers and powered with small diesel engines. These portable compression systems are typically referred to as construction compressors. Construction compressors are used to provide compressed air to jack hammers, riveting tools, pneumatic pumps, sand blasting operations and industrial paint systems. They are commonly seen at construction sites and on duty with road repair crews throughout the world.

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In an oil-free compressor, the air is compressed entirely through the action of the screws, without the assistance of an oil seal. They usually have lower maximal discharge pressure capability as a result. Oil-free compressors are used in applications where entrained oil carry-over is not acceptable, such as medical research and semiconductor manufacturing.

However, this does not preclude the need for filtration, as hydrocarbons and other contaminants ingested from the ambient air must also be removed prior to the point of use. Consequently, air treatment identical to that used for an oil-flooded screw compressor is frequently still required to ensure a given quality of compressed air. In an oil-injected rotary-screw compressor, oil is injected into the compression cavities to aid sealing and provide cooling sink for the gas charge. The oil is separated from the discharge stream, then cooled, filtered and recycled.

The oil captures non-polar particulates from the incoming air, effectively reducing the particle loading of compressed-air particulate filtration. It is usual for some entrained compressor oil to carry over into the compressed-gas stream downstream of the compressor. Oil-injected rotary-screw compressors are used in applications that tolerate a low level of oil contamination, such as pneumatic tool operation, crack sealing, and mobile tire service.

Among rotary-screw compressors, there are multiple control schemes, each with differing advantages and disadvantages. However, when the demand for compressed air is satisfied or reduced, instead of disconnecting power to the compressor, a device known as a slide valve is activated. This scheme is utilised by nearly all industrial air-compressor manufacturers.

Rotary compressor – Alf, Lysholm

Instead of starting and stopping the compressor, a slide valve as described above modulates capacity to the demand. Due to the limited adjustment in compressor power consumption relative to compressed-air output capacity, modulation is a generally inefficient method of control when compared to variable-speed comprssor. However, for applications where it is not readily possible to frequently cease and resume operation of the compressor such as when a compressor is driven by an internal-combustion engine and operated without the presence of a compressed-air receivermodulation is suitable.

Utilized by compressor companies Quincy Compressor, KobelcoGardner Denverand Sullairvariable displacement alters the percentage of the screw compressor ,ysholm working to compress air by allowing air flow to bypass portions of the screws. One way that variable displacement may be accomplished is by using multiple lifting valves on the suction side of the compressor, each plumbed to a corresponding location on the discharge.

In automotive superchargers, this is analogous to the operation of a bypass valve. However, a variable-speed drive provides for a linear compressr between compressor power consumption and free air delivery. Lyshoom harsh environments hot, humid or dustyvariable-speed drives may not be suitable due to the sensitivity of the equipment.

The twin-screw type supercharger is a positive displacement type device that operates by pushing air through a compresso of meshing close-tolerance screws similar to a set of worm gears. Twin-screw superchargers are also known as Lysholm superchargers or compressors after their inventor, Alf Lysholm. By comparison, conventional “Roots” type blowers have either identical rotors with straight rotors or mirror-image rotors with helixed rotors.


The Whipple-manufactured male rotor has three lobes, the female five lobes. The Kenne-Bell male rotor has four lobes, the female six lobes. Females in some earlier designs had four. By comparison, Roots blowers always have the same number of lobes on both rotors, typically 2, 3 or 4.

The working area is the inter-lobe volume between the male and female rotors. It is larger at the intake end, and decreases along the length of the rotors until the exhaust port. This change in volume is the compression. The intake charge is drawn in at the end of the rotors in the large clearance between the male and female lobes. At the intake end the male lobe is much smaller than its female counterpart, but the relative sizes reverse proportions along the lengths of both rotors the male becomes larger and the female smaller until tangential to the discharge port the clearance space between each pair of lobes is much smaller.

This reduction in volume causes compression of the charge before being presented to the output manifold. The rotary screw compressor has low leakage levels and low parasitic losses vs.

The supercharger is typically driven directly from the engine’s crankshaft via a belt or compresssor drive. Unlike the Compreszor type superchargerthe twin-screw exhibits internal compression which is the ability of the device to compress air within the housing as it is moved through the device instead of relying upon resistance to flow downstream of the discharge to establish an increase of pressure.

The requirement of high-precision computer-controlled manufacturing techniques makes the screw type supercharger a more expensive alternative to other forms of available forced induction. With later technology, manufacturing cost has been lowered while performance increased. All supercharger types benefit from the use of an intercooler to reduce heat produced during pumping and compression.

A clear example of the technology applied by the twin-screw in companies like FordMazdaMercedes and Mercury Marine can also demonstrate the effectiveness of the twin screw.

While some centrifugal superchargers are consistent and reliable, they typically do not produce full boost until near peak engine rpm, while positive displacement superchargers such as Roots type superchargers and twin-screw types offer more immediate boost.

The term “blower” is commonly used to define a device placed on engines with a functional need for additional airflow, such as a 2-stroke Diesel enginewhere positive intake pressure is needed to “scavenge”, or clear spent exhaust gasses from the cylinder and force a fresh intake charge into the cylinder before the compression stroke.

The term “blower” is applied to rotary screw, roots-type, and centrifugal compressors when utilized as part of an automotive forced induction system. From Wikipedia, the free encyclopedia. Retrieved 9 July Roots superchargingKenne Bell. Retrieved from ” compresskr Commons category link is on Wikidata. Views Read Edit View history. In other projects Wikimedia Commons. This page was last edited on 10 Decemberat By using this site, you agree to the Terms of Use and Privacy Policy.

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