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The basic structure of the piston refrigeration compressors [2012-06-27]

The basic structure of the piston refrigeration compressors
Body: two parts including the cylinder block and crankcase, usually made of high strength gray cast iron (HT20-40) cast a whole. It is a supporting cylinder liners, crank linkage and the weight of all components and ensure that all parts have the correct relative position of the body. The cylinder structure of cylinder liners, cylinder liner bore in the cylinder body, to facilitate the repair or replacement when the cylinder liner wear. Thus a simple structure, easy maintenance.
Crankshaft: the crankshaft is one of the main components of the piston refrigeration compressors, conveys the full power of the compressor. Its main role is to change the rotary motion of the motor through the connecting rod of reciprocating linear motion of the piston. Crankshaft to withstand tension and compression, shear, bending and torsional movement, alternating composite load, poor working conditions, required to have sufficient strength and stiffness and the wear resistance of the main journal and crank pin. Therefore, the crankshaft is generally 40, 45 or 50 high-quality carbon steel forging, but it is now widely used in ductile iron (such as QT50-1.5 and QT60-2, etc.) cast.
3, connecting rod: The connecting rod is the connection between the crankshaft and piston, it will crank rotary motion into reciprocating motion of the piston, and power transmission to the piston acting on the vapor. Connecting rod including a rod body, connecting rod, connecting rod bearing and connecting rod bolt.
Withstand the pull rod body work, pressure alternating load, it is commonly used quality carbon steel forging or ductile iron (such as QT40-10) casting, the shaft-shaped cross section and the middle of drilling a long hole as the oil duct.
Connecting rod small end through the piston pin and piston connected to the pin hole in the Canadian bush in order to improve wear resistance, shock resistance. The connecting rod commonly used tin phosphorus the bronze ZQSn10-made overall in the tubular cylindrical surface car ring groove and drill hole, the inner surface of the open axial tank.
Connecting rod and crankshaft connection. The connecting rod is generally made of the split in order to facilitate assembly and disassembly and repair. In order to improve the wear between the connecting rod and crank pin, the bulk of the holes generally are equipped with the bearing of the bearing alloy connecting rod bearing. Connecting rod bearing thin-walled and thick-walled two series of refrigeration compressors are thin-walled bearing. Bearing on the tile corresponding to the rod hole open hole.
The connecting rod bolts used to connect the split connecting rod and big bonnet. The connecting rod bolts is a serious force in the crank linkage parts, it not only by the repeated stretching and are subject to vibration and shock, it is easy to loose and fracture, resulting in a serious accident. Therefore, the design, fabrication, assembly of the connecting rod bolts have strict requirements. Rod bolt commonly used 40Cr, 45Cr steel and other manufacturing, fine thread, the installation requires a certain amount of preload to avoid changes in the load between the connecting rod up and down the tile and the crank pin loose percussion, to accelerate the machine parts damage. Preload large is also a disadvantage. Tighten the connecting rod bolt, the best force with torque wrench according to the instructions provided.
When 8 ≤ d ≤ 18, the connecting rod bolt tightening force:
F = 977.2-397.613d +63.2 d2-4.91042d3 +0.1875 d4-0.0028125d5
4, piston Group: piston set, piston, piston pin and piston rings of the general term. Piston group in the connecting rod driven for reciprocating linear motion in the cylinder, cylinder and other common a variable volume, in order to achieve suction, compression and exhaust process.
Pistons --- piston cylindrical and disc can be divided into two categories. Series refrigeration compressor piston tubular structure, which is composed of three parts from the top of the ring parts and skirt. Of the piston at the top of the closed cylinder face. Open on the piston ring Ministry of the cylindrical ring groove, install the piston rings and ring groove depth is slightly larger than the piston ring radial thickness of the piston rings have a certain degree of leeway. Piston skirt in the cylinder from the guiding role and to withstand the lateral pressure.
The piston material is generally aluminum or cast iron. Gray cast iron piston in refrigeration compressor wider application, but the quality of the cast iron piston and the poor thermal conductivity, therefore, in recent years, series refrigeration compressor piston aluminum alloy pistons. The advantages of aluminum alloy pistons, light weight, good thermal conductivity, surface anodized with good wear resistance. Aluminum alloy pistons lower mechanical strength than cast iron piston, abrasion resistance is also poor.
Piston pin --- piston pin is used to connect the piston and connecting rod small end parts, work under a complex alternating load. Damage to the piston pin will cause a serious accident, it is required to have sufficient strength, wear resistance and fatigue resistance, impact resistance performance. Therefore, the piston pin is usually on the 20th of steel, 20Cr steel, or 45 steel manufacturing.
Piston Rings --- piston ring including a steam ring and oil ring. The steam ring main role is to form a seal between the piston and the cylinder wall to prevent them from being compressed steam leakage from the clearance between the piston and cylinder wall. In order to reduce the compressed vapor leakage from the locking ring, multi-channel locking when the installation of the steam ring should be staggered. Central role of the oil cloth, oil, and scrape off the cylinder walls of the excess oil. The following steam ring can be installed one to three, the oil ring is usually only installed one and installed in the steam ring, oil ring cross-section shape beveled and slotted two kinds of slant oil ring is installed on the bevel should be.