JPH04311697A - Rotary compressor - Google Patents

Abstract

PURPOSE:To improve the wear resistance of the sliding face of a member such as a bearing element formed of sintered material so as to improve the durability and reliability of a compressor. CONSTITUTION:In a rotary compressor for compressing gas by the eccentric rotation of a roller 8 in a compression chamber 2, members formed of an iron group sintered alloy with boron treatment applied to the surface are built in as members 3, 5 provided with sliding faces with movable elements such as a rotary shaft 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary compressor incorporating sliding members such as bearings made of sintered material.

0002

2. Description of the Related Art FIG. 5 is a vertical cross-sectional view showing a general configuration of a vertical rotary compressor used in an air conditioner or the like. Reference numeral 1 indicates a closed case, and reference numeral 2 indicates a compression chamber. This compression chamber 2 contains a main bearing 3 and a cylinder 4.
, surrounded by sub-bearings 5. The main bearing 3 is fixed to the inner wall of the sealed case 1 with a flange portion 3a, and a cylinder 4 is fixed to the lower surface of the main bearing 3. The sub-bearing 5 is fixed to the lower surface of the cylinder 4 with its flange portion 5a.

Reference numeral 6 designates a rotating shaft that is rotatably supported by the main bearing 3 and sub-bearing 5. This rotating shaft 6 is rotationally driven by an electric motor section 7, and an eccentric crank section 6a of the rotating shaft 6 is rotated by an electric motor section 7. A roller 8 fitted onto the outside rotates eccentrically within the compression chamber 2 to compress the gas sucked in from the suction pipe 9. Note that the reference numeral 10 indicates lubricating oil stored in an oil reservoir at the bottom of the closed case 1.

In such a rotary compressor, many of the members having sliding surfaces with movable elements, such as bearing elements such as the main bearing 3 and the sub-bearing 5, are sintered.

[0005]

[Problems to be Solved by the Invention] Since the main bearing 3 and the sub-bearing 5 are members that form the compression chamber 2, if these sintered products are used, the compression will occur through the fine sintered holes inside. There is a risk of gas leaking. For this reason, conventionally, the sintered pores have been previously sealed by steam treatment after sintering. Through this steam treatment, a compound such as iron oxide is formed in the sintered pores, so that the abrasion resistance can be improved at the same time as the pore sealing treatment.

However, when using steam treatment,
Compared to its effectiveness as a pore sealing treatment, it is less effective in improving wear resistance and seizure resistance, so in rotary compressors with severe load conditions, it is necessary to forcibly supply a sufficient amount of Oil 10. Inconveniences have been pointed out. Therefore, the present invention solves the problems of the above-mentioned prior art and improves the abrasion resistance of the sliding surfaces of members such as bearing elements molded from sintered material, thereby improving durability and reliability. The purpose is to provide a rotary compressor with

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a member made of an iron-based sintered alloy whose surface is subjected to a boriding treatment as a member having a sliding surface with a movable element. It is characterized by the fact that it has been incorporated.

[0008]

[Operation] By the boriding treatment, boron permeates into the sintered pores existing inside the matrix of the sintered alloy to form a boride layer. The presence of this boride layer significantly improves the wear resistance of the sliding surface of the component, and the formation of the boride layer evenly seals the sintered pores.

[0009].

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary compressor according to the present invention will be described below with reference to the accompanying drawings. The rotary compressor according to this embodiment is the vertical rotary compressor shown in FIG.
, a sub-bearing 5 made of iron-based sintered alloy is incorporated as a member having a sliding surface with the movable element. The surfaces of the main bearing 3 and the sub-bearing 5 are subjected to a boron treatment, which will be described later.

These members are manufactured through the steps shown in FIG. First, as a sintering material, JIS standards (JIS
A mixture of the sintered material powders shown in Table 1 according to Z2550) is compacted into the general shape of the product using a mold. This green compact is heated at a high temperature to obtain a sintered product, and this sintered product is subjected to a boriding treatment as a post-treatment. In addition, regarding the density of the sintered product, in the case of bearing parts for a compressor, it is preferable to sinter and form the product so that the density is in the range of 6.2 to 7.0. If the density is less than 6.2, the formation of a boride layer will be insufficient even after the boride treatment described below, and conversely if the density is less than 7.
．． This is because if it is 0 or more, the mechanical strength will deteriorate, and there is a risk that the strength required for the bearing component will not be sufficient.

0012

[Table 1] Next, there are solid methods, liquid methods, gas methods, etc. for the boriding treatment, and any of them can be used, but in this example, a solution containing a boride and a boronization promoter is A liquid immersion method is used in which the sintered product is immersed inside and kept in a heated state in a heating furnace. The solution in which the sintered product is immersed is Na2B4O7, B2O3 solution containing Na as an accelerator.
The one to which F and NaBF4 are added is used. FIG. 3 is a diagram showing a heating cycle in a heating furnace. Heating time and heating temperature vary depending on the size of the sintered product and the thickness of the boride layer formed on its surface, but in the case of bearing parts for rotary compressors for general air conditioners, the preheating temperature T1 is 500°C. ℃ for about 30 minutes, then in another heating furnace, the heating temperature T2 is 600℃~1
000°C for 30 minutes to 3 hours.

The sintered product that has been subjected to the boriding process as described above is subjected to rough machining and finishing processes, and the dimensional accuracy and the surface accuracy of the sliding surface are adjusted to the required accuracy. Taking the main bearing 3 of FIG. 1 as an example, the inner diameter of the shaft hole 14 is finished within a predetermined dimensional tolerance, and the surface accuracy of the sliding surface of the shaft hole is adjusted. Note that the outer circumferential surface 15 of the main bearing 3 does not need to be particularly machined. Therefore, FIG. 4 is a diagram schematically representing the surface layer of the base of the main bearing 3 which has been subjected to the boriding treatment, and the reference numeral 16 indicates the base of the sintered alloy, and the reference numeral 17 indicates the countless numbers inside the base. Shows the sinter pores present. As a result of the boron treatment, the boron that has permeated into the sintered holes 17 combines with the metal elements of the sintered alloy to form a boride layer 18 . Regarding the shaft hole 14,
By cutting and grinding the sliding surface by finishing, the boride layer 18 is always partially exposed on the surface of the sliding surface. This boride layer 18 has a hardness of HV1000 to 2000, and is covalently or metallically bonded to the elements of the base material, so there is no risk of peeling, so the abrasion resistance of the sliding surface of the shaft hole 14 is as follows. The presence of the compound layer 18 significantly strengthens it. Regarding the main bearings 3 of the same type, we conducted a baking test using an abrasion tester under the same conditions on the main bearings 3 that had been subjected to boriding treatment and those that had been conventionally treated with steam. It was confirmed that the seizure resistance of Bearing 3 was improved by about 1.6 times.

On the other hand, regarding the outer peripheral surface 15 of the main bearing 3, the sintered holes 17 are uniformly sealed by the boronide layer 18. Therefore, even if the compression chamber 2 of the compressor is formed by the main bearing 3 and sub-bearing 5 which have been subjected to boron treatment, compressed gas will not leak to the outside through the sintered holes 17.

[0015]

[Effects of the Invention] As is clear from the above description, according to the present invention, a member made of an iron-based sintered alloy whose surface has been subjected to a boriding treatment is incorporated as a member having a sliding surface with a movable element. As a result, the wear resistance of the sliding surfaces such as bearings is strengthened, and its durability is further improved to ensure stable operation over a long period of time, resulting in a highly reliable rotary compressor.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main bearing, which is a sintered part subjected to a boriding treatment, in a rotary compressor according to the present embodiment.

FIG. 2 is a system diagram of the manufacturing process of sintered parts.

FIG. 3 is a diagram showing a heating cycle in boriding treatment.

FIG. 4 is a diagram showing a cross section of the surface layer of the base material of the sintered part.

FIG. 5 is a vertical cross-sectional view of the rotary compressor.

[Explanation of symbols]

2 Compression chamber 3 Main bearing 4 Cylinder 5 Sub bearing 6 Rotation axis 8 Roller 16 Sintered material base 17 Sintering hole 18 Boride layer

Claims (1)

[Claims] Claim 1: In a rotary compressor that compresses gas by eccentric rotation of a roller in a compression chamber, a member made of an iron-based sintered alloy whose surface has been subjected to a boriding treatment is used as a member having a sliding surface with a movable element. A lorry compressor characterized by its built-in.