As the heart of the refrigeration system, the performance of the compressor directly affects the energy efficiency and reliability of the entire system. Especially in the field of refrigeration, semi closed piston refrigeration compressors are widely used due to their high efficiency and stability. This article will explore in detail the key components of such compressors and the importance of their machining accuracy, and gain a deeper understanding of how these factors affect overall performance.

1、 Structural composition of semi closed piston compressor

1. Machine body and crankcase

Body: As the basic framework of the compressor, it is usually made of high-strength materials such as gray cast iron to ensure sufficient strength and rigidity. The body contains one or more crankcases, which are used to install transmission components such as crankshafts and connecting rods, and form a closed space to protect the electric motor and mechanical components.

  Crankcase: closely connected to the engine body, it is the supporting and accommodating space for moving parts such as the crankshaft and connecting rod.

2. Electric motor

The semi enclosed motor and compressor share the same sealed housing, and the motor directly drives the compressor to operate, connected to the crankshaft through a coupling. This design reduces losses during energy transfer and improves overall efficiency.

3. Crankshaft and connecting rod system

The crankshaft is one of the main components of a piston refrigeration compressor, transmitting all the power of the compressor. The crankshaft is fixed in the body through bearings, and balanced weights are installed at both ends to reduce vibration.

  Connecting rod: It is the connecting piece between the crankshaft and the piston, which converts the rotational motion of the crankshaft into the reciprocating linear motion of the piston, and transmits power to the piston to do work on the gas. The connecting rod includes components such as the connecting rod body, connecting rod small head bushing, connecting rod large head bearing shell, and connecting rod bolts.

4. Cylinder and piston components

Cylinder: It is the main component for compressing gas, and different materials and structural types are selected according to the different pressures, displacement, gas properties, and other requirements of the compressor. The inner surface of the cylinder should have good wear resistance, cooling and lubrication properties.

  Piston components: including pistons, piston pins, and piston rings. The piston performs reciprocating linear motion inside the cylinder, and together with the cylinder, forms a variable working volume to achieve processes such as suction, compression, and exhaust. The piston ring is used to seal the gap between the cylinder and the piston, preventing gas leakage.

5. Valve group

Each cylinder is equipped with a set of suction and exhaust valves to control the suction, compression, and discharge process of refrigerant inside the cylinder. These valves are usually composed of springs and valve plates, which automatically open and close according to changes in cylinder pressure.

6. Lubrication system

Including components such as oil pump, filter, and oil circuit, providing necessary lubrication and cooling for the compressor. The lubrication system can reduce friction and wear between moving parts, improve the operating efficiency and reliability of the compressor.

7. Safety protection device

Such as high and low voltage protection switches, temperature sensors, and overload protection relays, are used to monitor the operating status of the compressor and automatically shut it down in abnormal situations, preventing equipment damage and safety accidents.

2、 Factors to consider in the selection of semi closed piston compressors

So, in practical applications, what factors should be considered when selecting a semi sealed piston compressor?

1. Design requirements: Calculate the required cooling capacity based on factors such as the design temperature of the cold storage or refrigeration system, the type and quantity of stored items, and the heat load. This is the basis for selection, ensuring that the refrigeration capacity of the compressor can cover the highest peak demand, especially during the high temperature season in summer.

2. Temperature variation: Select a compressor that can flexibly adjust energy output based on changes in the working conditions of the cold storage, such as seasonal temperature fluctuations, storage frequency, etc. For large cold storage facilities, it may be necessary to consider multi-stage compression or parallel units to improve operational adaptability.

3. Operating environment: Consider factors such as temperature, humidity, and vibration in the operating environment of the compressor, and select the appropriate protection level and weather resistance.

4. Operating costs: including energy consumption, maintenance costs, spare parts costs, etc. Choosing high-efficiency and energy-saving compressors can reduce long-term operating costs.

5. Energy Efficiency Ratio (COP): COP is an important indicator for measuring the energy efficiency of a compressor, and the higher the COP value, the better the energy efficiency. When choosing, priority should be given to products with high energy efficiency.

6. Materials and processes: Understand the materials and processing techniques of key components of the compressor to ensure that it has sufficient strength and wear resistance to extend its service life.

7. After sales service: Good after-sales service is an important guarantee for ensuring the long-term stable operation of the compressor. When choosing, factors such as the manufacturer's after-sales service network, response time, and repair capabilities should be considered.

8. Brands and Manufacturers: Choose well-known brands and manufacturers with good market reputation, as their product quality is usually more reliable and their after-sales service is more comprehensive.

3、 The impact of manufacturing accuracy on performance

  The machining accuracy of a compressor determines the product quality, and the machining accuracy depends on the machining equipment. What are the advantages of a high-precision compressor?

1. Piston and cylinder: The gap between the piston and cylinder needs to be kept minimal and uniform to reduce refrigerant gas leakage. High precision machining can ensure precise control of this gap, thereby improving compression efficiency. The surface smoothness of pistons and cylinders has a direct impact on friction loss and wear. High precision machining can reduce surface roughness, thereby reducing friction loss and wear, and extending service life.

2. Connecting rod machining accuracy: The connecting rod connects the piston and crankshaft, and its machining accuracy directly affects the stability and reliability of the transmission. High precision machining can ensure that the connecting rod does not produce excessive vibration and noise during movement, improving the overall performance of the compressor.

3. Balance of crankshaft: The crankshaft needs to maintain good balance to reduce vibration. High precision machining can ensure uniform weight distribution of various parts of the crankshaft, thereby improving the operational stability of the compressor.

4. Energy efficiency improvement: High precision machining can reduce leakage and friction losses, thereby improving the energy efficiency of compressors. This helps to reduce the operating costs of the refrigeration system and improve economic efficiency.

5. Noise and vibration reduction: By improving machining accuracy, the internal structure and transmission system of the compressor can be optimized, thereby reducing the generation of noise and vibration. This helps improve the work environment and user experience.

6. Extended lifespan: High precision machining can reduce wear and failure, thereby extending the service life of the compressor. This is particularly important for refrigeration systems that require long-term operation.