CN101725504B - Refrigerant compressor - Google Patents

Abstract

A refrigerant compressor, the matrix of the crankshaft providing power is less than 5% ferrite, and the rest of the matrix is flake graphite cast iron containing Cr, Mo or Ni composed of pearlite. Alternatively, the matrix of the crankshaft is pearlite with an area ratio of 50% or more, and the rest of the matrix is spherical graphite cast iron made of ferrite. In addition, the material used for the main bearing supporting the crankshaft is flaky graphite cast iron (gray cast iron) that does not contain alloys, the graphite on the upper part of the main bearing is eutectic graphite, and pearlite exists in a matrix of 30% to 95%. .

Description

Refrigerant compressor

technical field

The present invention relates to a refrigerant compressor used in refrigerating and air-conditioning for businesses and households. the

Background technique

As a conventional refrigerant compressor, gray cast iron (flake graphite cast iron) is used for a crankshaft that transmits power of the compressor. In recent years, in response to high-efficiency requirements for compressors, crankshafts made of spherical graphite cast iron, which is more rigid than flake graphite, have been increasingly used. The structure of spherical graphite cast iron crystallizes spherical graphite, and matrix (matrix) pearlite and ferrite are dispersed. Ferrite is softer and more resistant to burning than pearlite, and has poor sliding resistance, so the ratio of ferrite in the matrix is limited as small as possible. the

On the other hand, calcined material or gray cast iron has been used in the past for the main bearings that support the crankshaft. If gray cast iron is used for the main bearing, the vicinity of the upper part of the main bearing is liable to be rapidly cooled during casting. Therefore, if the eutectic is refined from flake graphite which is originally elongated, the matrix is likely to be ferrite, which may cause problems in terms of wear resistance with the crankshaft. the

6 is a micrograph showing the metal structure of the upper part of the main bearing of the refrigerant compressor disclosed in JP-A-2000-110719. It can be seen that graphite is eutectic (ASTM (American Society for Testing and Materials) type D shape), and the matrix is ferrite (white part). The ferritic matrix is soft and therefore has poor wear resistance. the

Contents of the invention

As mentioned above, the majority of the matrix of the material of the crankshaft uses alloyed gray cast iron as pearlite. Furthermore, in the case of using spherical graphite cast iron for the crankshaft, a material that sufficiently secures pearlite in the matrix is selected. However, although gray cast iron is used for the main bearing that supports the rotation of the crankshaft, there is a problem in wear resistance with the crankshaft at the upper part of the main bearing. Therefore, it is necessary to provide stable mechanical reliability by controlling the metal structure of the upper part of the main bearing. the

Therefore, in the refrigerant compressor of the present invention, the matrix of the crankshaft that provides power is less than 5% ferrite, and the rest of the matrix is flaky graphite cast iron containing Cr, Mo or Ni composed of pearlite. Alternatively, the matrix of the crankshaft is pearlite with an area ratio of more than 50%, and the rest of the matrix is spherical graphite cast iron made of ferrite. The material used for the main bearing supporting the crankshaft is flaky graphite cast iron (gray cast iron) that does not contain alloys. The graphite in the upper part of the main bearing is eutectic graphite, and pearlite exists in a matrix of 30% to 95%. the

Common graphite is A-type graphite classified by ASTM, and almost the entire surface of the matrix is a pearlite structure. When casting the main bearing, especially the upper part of the main bearing is cooled rapidly, the graphite tends to become fine eutectic graphite (D-shaped graphite classified by ASTM). In this case, the matrix easily becomes ferrite. Furthermore, since the crankshaft is subjected to the vibration stress of the electric motor that is shrinkage fitted, the sliding condition becomes the strictest between the crankshaft and the upper part of the main bearing, and the wear resistance is slightly lowered. Therefore, by securing at least 30% or more of the hard pearlite matrix in the ferrite matrix in the matrix at this site, the wear resistance with the crankshaft can be ensured. the

Description of drawings

Fig. 1 is a longitudinal sectional view of a mechanism portion of a refrigerant compressor according to an embodiment of the present invention. the

Fig. 2 is a cross-sectional view showing a main part of a compression mechanism of the refrigerant compressor. the

Fig. 3 is a schematic view showing observation positions of the metal structure of the upper part and the lower part of the main bearing of the refrigerant compressor. the

Fig. 4 is a micrograph showing the metal structure of the upper part of the main bearing of the refrigerant compressor. the

Fig. 5 is a micrograph showing the metal structure of the lower part of the main bearing of the refrigerant compressor. the

Fig. 6 is a photomicrograph showing the metal structure of the upper part of a main bearing of a conventional refrigerant compressor. the

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings. the

As a conventional refrigerant compressor, a rotary compressor is one of the typical ones. Therefore, a case where a rotary compressor is used as a refrigerant compressor will be described. Fig. 1 is a longitudinal sectional view of a mechanism portion of a refrigerant compressor according to an embodiment of the present invention, and Fig. 2 is a cross-sectional view showing a main part of a compression mechanism of the refrigerant compressor. the

In FIG. 1 , the refrigerant compressor includes a motor unit 2 , a compression mechanism unit 3 , and the like in a closed container 1 . The motor unit 2 is composed of a rotor 2 a and a stator 2 b. A crankshaft 8 is fixed to the rotor 2 a by press fitting or the like, and the crankshaft 8 is rotatably supported by a main bearing 9 and a sub bearing 10 . The compressor unit 3 includes a cylinder 20 , a roller 7 , an eccentric portion of the crankshaft 8 , vanes 21 , a main bearing 9 and a sub bearing 10 . Here, the cylinder 20 has the suction hole 5 and the cylinder groove 23 in the radial direction. The outer peripheral surface of the roller 7 rotates eccentrically while sliding along the inner peripheral surface of the air cylinder 20 . The eccentric portion of the rotating shaft 8 is inserted into the inner peripheral surface of the roller 7 in a slidable manner. The vane 21 is accommodated in the cylinder groove 23 so as to reciprocate and slide freely, and the tip end is pressed against the roller 7 by the urging force of the spring 24 and the counter force (discharge pressure), and the inner space of the cylinder 20 is divided into a suction chamber 25 with compression chamber 26. The main bearing 9 and the auxiliary bearing 10 close both end faces of the cylinder 20 . the

Next, the operation of the rotary compressor configured as described above will be described. The rotor 2a is rotated by energizing the motor unit 2 from the outside, and the shaft 8 is driven to rotate. When the shaft 8 rotates, the roller 7 slidably mounted on the eccentric portion performs planetary motion (planetary movement: counterclockwise rotation in FIG. 2 ) while slidingly contacting the inner peripheral surface of the cylinder. As a result, refrigerant gas such as HFC (hydrofluorocarbon) is sucked into the suction chamber 25 from the suction pipe 4 and through the suction hole 5 . Simultaneously, in the compression chamber 26 , the pressure-increased refrigerant gas is discharged from the discharge groove 22 and through the discharge hole 6 into the closed container 1 . the

In FIG. 1, the position of the discharge hole 6 is drawn away from the suction hole for easy observation, but actually, as shown in FIG. the

At this time, the vane 21 partitioning the suction chamber 25 and the compression chamber 26 is pressed against the outer peripheral surface of the roller 7 by the pressure applied to the back of the vane by the spring 24 . The tip of the blade 21 slides on the outer peripheral surface of the roller 7 , and the side surface of the blade 21 slides on the inner wall surface of the cylinder groove 23 . The vane 21, the roller 7, and the cylinder groove 23 are lubricated with the refrigerating machine oil 11 stored at the bottom of the closed container 1 in a steady state of operation. However, there is not enough refrigerating machine oil in the sliding part at the time of starting, and a small amount of refrigerating machine oil 11 contained in the sucked refrigerant gas is used. Here, a small amount of refrigerating machine oil 11 is discharged from the compressor together with the refrigerant gas, and returns to the compressor from the suction pipe 4 again after circulating through the refrigerating cycle. the

Crankshaft 8 generally uses low alloy cast iron or nodular graphite cast iron. As described above, lubricating oil cannot be sufficiently supplied under sliding conditions at the time of start-up of the hermetic rotary compressor. In particular, the crankshaft 8, the main bearing 9, and the sub-bearing 10 are rotating, so it is difficult to form an oil film, which is a stricter sliding condition. Furthermore, since the HFC refrigerant itself which has been adopted for environmental protection in recent years lacks lubricity, the sliding conditions of the rotary compressor using the HFC refrigerant are particularly severe. the

Fig. 3 is a schematic view showing observation positions of the metal structure of the upper part 31 and the lower part 32 of the main bearing of the refrigerant compressor according to the embodiment of the present invention, and Fig. 4 is a micrograph showing the metal structure of the upper part of the main bearing of the refrigerant compressor . the

As shown in FIG. 3, the thickness of the upper part of the main bearing 9 becomes small. Graphite is eutectic (D-shape classified by ASTM), but the matrix is a structure in which pearlite (gray) is precipitated in ferrite (white). It can be seen that in the example of the microscope photo in Figure 4, more than 80% of the matrix is pearlite, and the graphite is eutectic, but there is almost no difference between the matrix and the normal structure (A-type graphite + pearlite) in the lower part of the main bearing . the

The upper part of the structure of the main bearing 9 according to the embodiment of the present invention is rapidly cooled and is eutectic graphite. However, in order to ensure the amount of pearlite in the matrix, the matrix is strengthened by adjusting the inoculation and adding pearlite-promoting elements. . Therefore, it is of course possible to use alloy-containing gray cast iron for the crankshaft 8, and even when the crankshaft is made of nodular graphite cast iron containing ferrite in the matrix, mechanical slidability can be ensured. the

5 is a micrograph showing the metal structure of the lower part of the main bearing of the refrigerant compressor according to the embodiment of the present invention. It can be seen that it is the structure of the original gray cast iron (the shape of graphite is A shape classified by ASTM), and most of the matrix is pearlite. Since pearlite is harder than ferrite, it has excellent wear resistance. the

As mentioned above, the matrix of the crankshaft 8 that provides power is ferrite with 5% or less, and the rest of the matrix is flake graphite cast iron containing Cr, Mo or Ni composed of pearlite. Alternatively, the base of the crankshaft 8 is spherical graphite cast iron having a pearlite area ratio of 50% or more and the rest of the base is ferrite. In addition, the material used for the main bearing 9 supporting the crankshaft 8 is alloy-free flake graphite cast iron (gray cast iron), and the graphite on the upper part of the main bearing 9 is eutectic graphite, and more than 30% of Less than 95% pearlite. the

Common graphite is A-type graphite classified by ASTM, and almost the entire surface of the matrix is a pearlite structure. When the main bearing 9 is cast, especially the upper part of the main bearing 9 is cooled rapidly, graphite tends to become fine eutectic graphite (D-shaped graphite classified by ASTM). In this case, the matrix easily becomes ferrite. Furthermore, since the crankshaft 8 is subjected to the vibration stress of the electric motor after being shrink-fitted, the sliding condition becomes the strictest between the crankshaft 8 and the upper part of the main bearing 9, and the wear resistance is slightly lowered. Therefore, at least 30% or more of hard pearlite in the ferrite matrix is ensured in the matrix of this portion, thereby ensuring wear resistance with the crankshaft 8 . the

Because the crankshaft 8 is subjected to the vibration of the motor after shrink fit, its wall thickness is designed to be smaller. Therefore, the material of the gray cast iron on the upper part of the main bearing 9 is also the same as the finished product of the main bearing 9. The upper wall Thick is cast into smaller sizes. Generally, this part is located away from the ingate which is the inlet of molten metal during casting, and because the wall thickness is thin, it is easy to be cooled rapidly, and the graphite does not grow sufficiently, and it is difficult to become flake graphite. Therefore, crystals are precipitated as eutectic graphite, and pearlite in the matrix is not sufficient, and a ferrite matrix is formed, which tends to cause problems in terms of wear resistance. Of course, in terms of casting, by using inoculum in molten metal, although it is possible to achieve a certain degree of homogenization of the structure, there is a certain limit. In the present invention, the amount of pearlite in the matrix tissue of this part is ensured by optimizing inoculation and adding pearlite-promoting elements, etc., so that sufficient sliding properties with the crankshaft 8 can be ensured. the

The refrigerant used in the refrigerant compressor is HCFC (hydrochlorofluorocarbon), and the refrigerating machine oil is mineral oil. Alternatively, the refrigerant used in the refrigerant compressor is HFC, and the refrigerating machine oil is ester or ether oil. the

As a result, even if the refrigerant is HCFC or HFC refrigerant with stricter lubrication conditions, sufficient mechanical sliding reliability can be ensured. the

Claims (2)

1. coolant compressor is characterized in that:

The matrix that the bent axle of power is provided is the ferrite below 5%, remaining matrix is the flake graphite cast iron that contains Cr, Mo or Ni that is made of pearlite, perhaps the pearlite area ratio is more than 50%, remaining matrix is the nodular cast iron that is made of ferrite, the employed material of main bearing that supports described bent axle is the flake graphite cast iron that does not comprise alloy, the graphite on described main bearing top is eutectic graphite, and has the pearlite below 95% more than 30% in the matrix of described main bearing.

2. coolant compressor as claimed in claim 1 is characterized in that:

Refrigeration agent is HCFC, and refrigerator oil is mineral oil, and perhaps described refrigeration agent is HFC, and described refrigerator oil is ester or ether oil.

Images