Rotary compressors: device, operating principle and application

Rotary compressor plants have become widespread in factories and small workshops. The equipment for injection of compressed air of this type is characterized by a reliable design, which ensures high productivity. To this it is worth adding practicality in servicing the unit. At the same time, rotary compressors have a number of disadvantages that limit the scope of their use.

Compressor arrangement

Rotational models represent a whole group of compressors, differing in design and working qualities. The main share of this type of stations is made up of air rotor plants. In this case, the device of rotary compressors is based on the motor shaft providing the working function. The rotor is attached to the shaft, but in the process of work the motion is not from the center of the circle, but eccentrically. This is due to the fact that the shaft of traditional models has a bias.

Functional stuffing, in turn, is enclosed in a metal case - usually a cylindrical shape. Without fail, a technological gap is maintained from the shaft with the rotor to the surface of the housing. During operation, the rotary air compressor will reduce it in accordance with a value equal to the above displacement of the shaft. Also, special plates and flaps are used to further protect and prevent the flow of technical fluid .

Principle of operation

With each rotation of the rotor, a free zone will form between the cylinder wall and the working group. At this point, it is filled with dry superheated or saturated steam - it can also be a variety of refrigerants and oily liquids. On the other hand, the process of compressing this zone is started by pressure valves that facilitate the absorption of the same vapors from the evaporator. When performing a multiple cycle of revolutions, the optimum working pressure is achieved, which allows performing the main function of injecting compressed air, for which a rotary compressor is used. The principle of operation of rotary models provides for automated oil supply. This is especially true for industrial units operating under high loads. Refilling with liquid is realized from a special tank - it enters the oil separator to a certain level. If necessary, the oil can be cooled with water.

Types of construction

Generally, rotary-type compressors are produced with swinging and immovable compression elements. In the first model of the working group, it is assumed that the refrigerant is compressed by means of a rotary eccentric on the engine. This is in some way an independent element that provides a relatively high compression ratio. However, due to increased friction, such aggregates are considered ineffective. At least, costly in terms of maintenance. On the other hand, lamellar rotary compressors allow to eliminate the undesirable effect of intense friction. The compression of the refrigerant is realized by plates fixedly mounted on the shaft. They are stationary relative to the shaft itself, but their compression function is carried out together with it.

Features of spiral models

Spiral-type models are more often used in installations of small and medium power - for example, in refrigerators. The working group is formed by two metal spirals - one is integrated into the other. The basic helix is stationary, and the outer one rotates around the axis. What is more important, in the compressors, these elements have a special involute profile, allowing rolling, but not slipping. It assumes a spiral compressor and the movement of the point of contact of the working elements. It is in it that the cycles of squeezing and pushing out through the central hole occur. By the nature of the compression, the spiral aggregates can be called softer and more sparing. Therefore, the output power allows them to be used in medium and small capacity equipment. It is worth emphasizing and the complexity of the technical implementation of such compressors, due to the need for tight fit of the spiral elements and tightness of the ends.

Protection systems of the unit

The high quality of the element base and the carefully calibrated layout of functional parts is not enough for the equipment to regularly perform its tasks in production conditions. Therefore, modern models can not do without additional protective systems. First of all, this is an automatic shutdown of the unit when fixing network overloads. Thus, the motor control unit is protected. Since rotary compressors are also prone to overheating of the mechanical part, it is introduced into the design and cooling system. It minimizes thermal loads that affect both technical fluids and structural details. For models with electronic control, self-diagnosis systems are provided. Thanks to the sensors, the compressor without operator involvement can detect malfunctions of the units and, depending on the nature of the failure, or also independently correct them, or provide an appropriate alarm signal through the indicators.

Main characteristics

The performance of the compressor determines with which equipment a particular model will be able to work optimally. This characteristic is expressed by the ratio of the released volume of air to a unit of time - usually a minute. Household units most often have a capacity of about 100 l / min. This is quite enough for working with pneumatic tools like sprayers, grinders and cloggers. But if, for example, simultaneous use of several pneumatic devices is planned on the construction site, then the productivity should increase to 150-200 l / min and above. In addition, a compressor with a rotating rotor is desirable to be used with a reserve of power potential. That is, the total planned load will need to add 15-20%. This increase is justified by a decrease in the load on the element base. An essential characteristic is the working pressure, which varies on average from 6 to 15 bar. In this case, the selection is also made based on the requirements for a specific instrument. For optimum performance, 2 points are added to the nominal pressure rating of the tool.

Consumables

In the working process of rotary compressors, oil plays a special role. The main function of compressor fluids is to maintain the wear resistance of parts, to prevent depressurization and formation of deposits. But modified compositions with individual improved properties are also on the market - for example, it can be frost resistance, corrosion protection, etc. As for the type of substrate, a scroll compressor operating at temperatures up to 100 degrees can be filled with synthetic agents. If this threshold is increased, then more expensive but high-quality mineral oils should be consulted. Technical accessories are also a necessary addition. In this group of consumables, hoses, adapters, fittings, valves, filters and fasteners are selected. Thanks to the component equipment and the infrastructure of interaction of the compressor with a working tool or equipment is organized.

Manufacturers and prices

Although the segment of compressors as such is very extensive and offers products from almost all major manufacturers of construction and industrial equipment, the category of rotary models is the least popular, therefore, the proposals are substantially limited. The most popular installations are manufacturers of refrigeration equipment Matsushita, Galanz, Toshiba, etc. They cost about 20 to 50 thousand rubles. Abac, FUBAG and COMARO are recommended for the spheres of construction and industrial use. These companies offer mainly high-performance units designed for operation in large enterprises. At a price, rotary compressors of this type also differ markedly - on average they cost 200-300 thousand. By the way, one of the most expensive stations offers Abac in its line of GENESIS. This model with a capacity of 3320 liters / min and working pressure of 8 bar, available for 650 thousand.

What to consider in the choice?

The choice of rotary compressors is usually suitable for consumers who need a low-cost, low-noise and at the same time productive source of compressed air. Therefore, the industry with all its operational features will be the main area where this type of compressor is used. The rotary engine is most often oriented to 380V mains voltage. If there is no three-phase line on the site of use, you will have to make a discount already for performance, focusing on 220 V. In addition to the basic operating values, the design is taken into account. Usually it is stationary, but even large-scale modifications in some versions provide for the possibility of moving. This nuance should be borne in mind if several technological points located in different places are planned to be serviced at the facility.

Maintenance

In the conditions of regular operation, the preventive check sessions should be performed in accordance with the schedule. Oil change and revision of connecting parts are performed before each procedure of equipment application. If there is a critical deformation of the elements or deterioration of the consumables, the air compressors are repaired, which can be expressed by replacing the faulty components. Technical recovery of the same deformed elements is undesirable, since their service life will in any case be lower.

Special attention is paid to the channels of oil supply and cooling liquids. Filters, membranes, seals and hoses interact with them - this infrastructure should be regularly cleaned, washed and also replaced, if necessary. By the way, the repair of air compressors in the form of restoration of the fan blades and radiator grilles is carried out just in cases when the maintenance staff paid insufficient attention to the fight against blockages and contamination of the structure.

Applications

It has already been said that compressor plants are often used to service a construction tool on a pneumatic basis. But this is only part of the tasks that such types of aggregates can perform. Their specialized niche is still the refrigeration equipment. And it can be and directly industrial refrigerators with refrigerators, and household conditioners. In the second case, compact and low-power rotary compressors are used. The use in industry is also emphasized on the possibility of the installation with refrigerants - the equipment is used at the technological stages of processing slaves, meat, semi-finished products and other food products.

Conclusion

With all the differences with reciprocating compressors, rotary units operate on the same principle of crowding out the serviced medium. The differences are due to the structural implementation of mechanics, which provides the whole process. Among the advantages that rotary compressors have on the background of piston counterparts, it can be noted the ability to connect to the engine, the balance of travel with reduced vibration, uniform supply of gas media and the absence of a group of valves. But there are disadvantages. Thus, for example, the dense interaction of mechanical parts contributes to their rapid physical deterioration. There are also weaknesses in rotary models in terms of manufacturing technology - they require high-precision assembly, otherwise the unit will not be able to match the stated performance indicators.