JPH025784A - Rotary compressor - Google Patents

Abstract

PURPOSE:To have smooth sliding with no seizure or wear for a long period of time by furnishing a shaft whose base material surface is covered with a ceramic coating layer having a high close contact property. CONSTITUTION:The surface of the shaft base material consisting of a metal or alloy having undergone surface hardening treatment is covered with ceramic coating. Examples of this metal constituting the base material are ferric materials such as chromium-molybdenum alloy steel, gray cast iron, and carbon steel. As the surface hardening treatment, for ex., can be cemented nitrization, cemented quenching, nitrization, high frequency hardening, etc. This accomplishes a shaft, to whose base material a ceramic coating layer is in close contact in good performance, and its excellent anti-abrasiveness and low friction characteristic can be exerted for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a rotary compressor, and more particularly to a rotary compressor with an improved shaft.

(Prior Art) A rotary compressor generally has a structure shown in FIGS. 1 and 2. That is, 1 in the figure is a cylinder, and above and below this cylinder 1 are a main bearing 2 and a sub bearing 3.
are each fixed with screws or the like. A valve seat portion 4 is formed in the main bearing 2, and a discharge port 5 is opened in the valve seat portion 4. A shaft 6 supported by the main and sub-bearings 2.3 is inserted into the cylinder l, and the shaft 6 rotates eccentrically, for example, clockwise, via an eccentric shaft 7. Rotor 8? It has been d+i.

Further, the cylinder 1 has a suction port 9 opened therein.

A blade groove 10 is opened in a portion of the cylinder 1 between the suction port 9 and the discharge port 5, and the blade groove 10 is always biased by a spring 11 to rotate the rotor 8 in the cylinder 1. A blade 12 is inserted which makes sliding contact with the rotor 8 and divides the space between the inner surface of the cylinder l and the rotor 8 into a low pressure space Ps and a high pressure space Pd. Note that the upper and lower surfaces of this blade 12 are in sliding contact with the main and sub-bearings 2.3.

Conventionally, the supports and bearings incorporated in the above-mentioned rotary compressor have mainly been used in combination with iron-based castings and sintered materials or castings, as shown in Table 1 below.

Table 1. However, the above shaft and bearing combination cannot adequately handle the high speeds and high loads of rotary compressors.
There was a demand for more reliable materials.

For this reason, attempts have been made to use a shaft with a ceramic coating on the base material surface, but the problem is that the ceramic-nox coating layer peels off when exposed to high speeds and high loads, making it impractical. was there.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a rotary compressor equipped with an extremely reliable shaft that can withstand high speeds and high loads. It is something.

[Structure of the Invention (Means for Solving Problems)] The present invention provides a rotary compressor characterized by having a shaft having a ceramic coating on the surface of a base material made of a surface-hardened metal or alloy. It is.

Examples of the metal or alloy constituting the base material include chromium-molybdenum alloy steel (JISS CM415-4
35), iron-based materials such as gray cast iron (JIS-FCD40-70) and carbon steel (JIS-330C-555C).

In particular, alloy steels such as J Is-5l5-5C are suitable because they have good workability, high toughness (and high strength, are high-grade steels, and are easy to perform carbonitriding and carburizing quenching, which are surface hardening treatments described below). It is.

As the surface hardening treatment, for example, carbonitriding, carburizing and quenching, nitriding, induction hardening, etc. can be employed.

The surface hardness resulting from such surface hardening treatment is desirably HV 500 or more. In addition, among the surface hardening treatments, carbonitriding and carburizing quenching can form a nitrided layer or a carbonized layer on the surface of the base material, which acts as a binder for the ceramic coating layer and improves the adhesion of the coating layer to the base material. It is effective because it can improve

Examples of the ceramics include SIN.

Ti N, BN, A, f? Examples include N5SI C5Ti C and the like. The ceramic coating layer is
For example, it can be formed by a low-pressure plasma CVD method, a PVD method, a plasma spraying method, an ion-blating method, etc., and a low-pressure plasma CVD method is particularly preferable because it allows low-temperature treatment without causing thermal deformation to the base material. Moreover, the thickness of such a ceramic coating is preferably in the range of 1 to 3 μm.

Examples of the material for the bearing used in combination with the shaft include sintered alloy, sintered high-speed steel, gray cast iron, and the like. An example of such a shaft and bearing combination is shown in Table 2 below.

Table 2 (Function) According to the present invention, by applying a ceramic coating to the surface of the base H made of a surface-hardened metal or alloy, the ceramic scorch ive layer is well densely packed against the base material. can be configured. As a result, such shafts and bearings can be incorporated into rotary compressors to provide high-speed,
When the shaft is rotated under high load conditions, the ceramic coating layer on the surface of the shaft can be prevented from peeling off.
It can withstand high loads and exhibits the excellent wear resistance and low friction properties of the ceramic coating layer over a long period of time.

(Example of the invention) The present invention will be explained in detail below.

Example 1.2 First, a shaft base material was produced by die forging and cutting alloy steel (J Is-3Cl5-3C), and then carbonitrided to harden the surface. After finish grinding, the surface of the base material is coated with a thickness of 2 μm by low pressure plasma CVD method.
The shaft was manufactured by coating a SiN layer of .

The rotary compressor shown in FIGS. 1 and 2 described above was assembled using the obtained shaft and bearings made of the materials shown in Table 3 below.

Comparative Example 1.2 A shaft base material was produced by die-forging and cutting spheroidal graphite cast iron (J I 5-FCD50), and further finishing grinding.The shaft base material was then coated with a phosphate film on the surface of the base material and the shaft was was manufactured.

The rotary compressor shown in FIGS. 1 and 2 described above was assembled using the obtained shaft and bearings made of the materials shown in Table 3 below.

Therefore, for the rotary compressors of Example 1.2 and Comparative Example 1.2, the surface pressure applied to the shaft was increased in steps while the shaft was maintained at the maximum rotational speed under no-lubrication conditions. The critical Pv value at which the shaft is damaged was measured. Note that the Pv value is a basic measure of shaft-bearing performance, and is determined by the surface pressure applied to the shaft (PCK9/cm) and the circumferential speed of the shaft y (m/cm).
5ee). In addition, the limit Pv of Comparative Example 1
Using this value as a reference value, the ratio (effectiveness ratio) to the limit Pv value of Comparative Example 2 and Example 1.2 was determined. These results are also listed in Table 3 below.

As is clear from Table 3 above, Comparative Example 1 and Example using bearings made of the same material (sintered alloy, J Is-SMF4)]
Comparing the above, it can be seen that the former has a limit Pv value of 205, while the latter has an extremely high limit Pv value of 270, indicating that it has excellent performance in withstanding high speeds and high loads. In addition, when comparing Comparative Example 2 and Example 2, which use bearings made of the same material (gray cast iron; J I 5-Fe12), the limit Pv of the former is
value is 269, while the latter's limit Pv value is 370.
It can be seen that it has excellent performance in withstanding extremely high speeds and high loads.

[Effects of the Invention] As detailed above, the rotary compressor of the present invention includes a shaft provided with a highly dense ceramic coating layer on the surface of the base material, and the ceramic coating layer is superior in combination with the support and bearing. High speed and high load due to wear resistance and low friction! Ii (particularly under oil-free condition F), it has remarkable effects such as being able to perform smooth sliding without seizure or wear for a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a general rotary compressor, and Fig. 2 is a (M sectional view) of the rotary compressor shown in Fig. 1. ... Cylinder, 2... Main bearing, 3... Sub bearing. ,6
... shaft, 8 ... rotor, 9 ... suction port, 10 ...
-Blade groove, 12...Blade, Ps...Low pressure space, Pd...High pressure space.

Claims (1)

[Claims] A rotary compressor characterized by having a shaft whose surface is made of a surface-hardened metal or alloy and whose surface is coated with ceramics.