Refrigerator compressor device: types and classification of refrigeration compressors

The operation of domestic and industrial refrigeration equipment directly depends on the circulation of the refrigerant, the compressor installation is responsible for this process. In fact, this is the most important structural element, without which a home refrigerator will interest only recycle receivers. In order to repair or replace this device, it is important to understand how it works. In this publication, we will talk about the internal structure of various compressors of household refrigerators and their features.

Briefly about the types of equipment

According to the principle of operation, this equipment can be divided into four types:

• Steam ejector, as a rule, water acts as a refrigerant. It is used in various industrial processes.
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• Absorption, for work uses not electric, but thermal energy.
• Thermoelectric, based on Peltier elements, widespread use remains in doubt due to low efficiency (detailed information about these devices can be found on our website).
• Compressor

It is the latter type of equipment that is widely used in domestic and industrial units.

Compressor for the refrigerator: principle of operation

To understand the purpose of this unit, you should consider the scheme of the equipment. A simplified version, where only the main structural elements are indicated, is given below.

Designations:

• A - Evaporative radiator, as a rule, is made of copper tubes and is located inside the chamber.
• B - Compressor unit.
• C - Condenser, is a radiator assembly located on the back of the unit.
• D - Capillary tube, used to equalize the pressure.

Now consider the system operation algorithm:

1. Using a compressor (B in fig. 1), refrigerant vapor (usually freon) is injected into the condenser radiator (C). Under pressure, their condensation occurs, that is, freon changes its state of aggregation, passing from vapor to liquid. The heat generated by the radiator grill dissipates into the surrounding air. If you notice, the back of a working installation is noticeably hot.
2. After leaving the condenser, the liquid refrigerant enters the pressure equalizer (capillary tube D). As you move through this node, the pressure of freon decreases.
3. The liquid refrigerant, now under low pressure, enters the evaporative radiator (A), under the influence of heat of which it again changes the state of aggregation. That is, become steam. In the process, the evaporative radiator is cooled, which in turn leads to a decrease in temperature in the chamber.

Then the cycle repeats, until the required temperature is established in the chamber, after which the sensor sends a signal to the relay to turn off the electrical installation. As soon as the temperature rises above a certain threshold, the device turns on and the installation operates according to the described cycle.

Based on the above, we can conclude that this device is a pump that provides circulation of refrigerant in the cooling system.

Classification of compressors in refrigeration equipment

Despite the general principle of operation, the design of mechanisms may vary significantly. Classification is carried out according to the principle of operation into three subtypes:

1. Dynamic. In such devices, refrigerant circulation is carried out under the influence of a fan. Depending on the design of the latter, they are usually divided into axial and centrifugal. The first are installed inside the system, and in the process of work they pump pressure. Their principle of operation is the same as that of a conventional fan.

   

The second has a higher efficiency due to the growth of kinetic energy, under the influence of centrifugal force.

The main disadvantage of such systems is the deformation of the blades due to the torsion effect that occurs under the influence of torque. Dynamic installations are not used in household equipment, so for us they are not of interest.

1. Volume. In such devices, the compression effect is produced using a mechanical device driven by an engine (electric motor). The effectiveness of this type of equipment is significantly higher than that of screw units. It was widely used until the advent of low-cost rotary devices.
2. Rotary. This subspecies is distinguished by its durability and reliability; just such a design is installed in modern household units.

Given that the last two subspecies are used in household devices, it makes sense to consider their device in more detail.

The device of the piston compressor of the refrigerator

This unit is an electric motor with a vertical shaft, the structure is placed in a sealed metal casing.

When you turn on the power of the starting relay, the motor drives the crankshaft, so that the piston attached to it starts to reciprocate. As a result of this, freon vapor is evacuated from the evaporative radiator (A in Fig. 1) and injection of refrigerant into the condenser. This process is facilitated by a valve system that opens and closes when pressure changes. The main elements of the piston design are presented below.

Designations:

1. The lower part of the metal casing.
2. Mounting the stator of an electric motor.
3. Motor stator.
4. The body of the internal electric motor.
5. Cylinder fasteners.
6. Cylinder cover
7. Valve mounting plate.
8. Cylinder body.
9. Piston element.
10. A shaft with a crank neck.
11. The wings.
12. Rocker slider.
13. Coiled spiral tube for refrigerant injection.
14. The upper part of the sealed casing.
15. Shaft.
16. Suspension mount.
17. Spring.
18. Suspension bracket
19. Bearings mounted on a shaft.
20. Anchor of an electric motor.

Depending on the design of the piston system, these devices are divided into two types:

1. Crank. They are used to cool large-volume chambers, since they withstand a significant load.
2. Crank-rocker. They are used in two-chamber refrigerators, where two units work together (for the freezer and the main container).

In later models, the piston is not driven by an electric motor, but by a coil. This implementation option is more reliable due to the lack of mechanical transmission, and economical because it consumes less electricity.

Please note that piston units cannot be repaired under domestic conditions, since disassembling them leads to a loss of tightness. Theoretically, it can be restored, but this requires specialized equipment. Therefore, when devices fail, as a rule, they are replaced.

The device of rotor mechanisms

To be precise, such devices must be called two-rotor, since the necessary pressure is created due to two rotors with counter rotation.

Inside the compressor, freon, falling into a compressible "pocket" is pushed into the hole of a small diameter, which creates the necessary pressure. Despite the relatively low rotor speed, the necessary compression ratio is created. Distinctive features: low power, low noise. The main structural elements of the mechanism are presented below.

Designations:

1. Branch pipe.
2. Oil separator.
3. Tight casing.
4. Stator fixed on the casing.
5. Designation of the inner diameter of the casing.
6. Anchor diameter designation.
7. Anchor.
8. Shaft.
9. Sleeve.
10. Blades.
11. Bearing on the armature shaft.
12. Stator cover.
13. Introductory tube with valve.
14. Camera battery.

The device of the inverter compressor of the refrigerator

In fact, this is not a separate view, but a feature of the work. As already discussed above, the installation motor turns off when the threshold temperature is reached. When it rises above the set limit, the engine is connected at full power. This starting mode leads to a decrease in the resource of the electromechanism.

The opportunity to get rid of this drawback appeared with the introduction of inverter installations. In such systems, the engine is constantly on, but when the desired temperature is reached, its rotation speed decreases. As a result, the refrigerant continues to circulate in the system, but much more slowly. This is quite enough to maintain the temperature at a given level. With this mode of operation, the service life is extended and less energy is consumed. As for the other characteristics, they remain unchanged.

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