JPH0571484A - Compressor - Google Patents

Abstract

PURPOSE:To prevent a drop in compressor capability due to a difference in linear thermal expansion coefficient, and improve the abrasion resistance or the like of the slide member of a compressor and the durability thereof by forming the member with the sintered body of partially stabilized zirconia blended with the predetermined ratio of yttria. CONSTITUTION:In a roller piston type compressor for an air conditioner, a rotor 4 rotating eccentrically with a shaft 3 performs intake and compression strokes in a cylinder 2 fixed to the internal surface of a sealed casing 1. A vane 5 is so fitted to the cylinder 2 as to be free to advance and retreat, and the slidable contact of the end of the vane 5 with the roller 4 cellularizes a cylinder chamber 7 into an expansion chamber 7a and a compression chamber 7b. Among slide members used for the compressor so constructed, the vane 5 sliding along the external surface of the cylinder 2 is formed with a sintered body of partially stabilized zirconia (Y2O3-PSZ) blended with 3 to 8mol% of yttria (Y2O3). According to this construction, the vane 5 can be improved in respect of abrasion resistance or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor incorporated in a refrigeration system and an air conditioner, and more particularly to a compressor having a sliding member with improved mechanical strength.

[0002]

2. Description of the Related Art For example, in a rotary compressor, parts such as vanes and rollers are required to have mechanical strength capable of withstanding long-term operation under severe conditions. It is essential to select a material that has excellent mechanical properties such as hardness and abrasion resistance. In recent years, as the performance of refrigeration and air-conditioning systems has improved, the operating conditions of compressors have become stricter and faster, and the load or peripheral speed acting on the sliding members or the load based on inertial force has been applied. Tend to increase more and more. Therefore, as materials that meet the design requirements of sliding members for compressors, aluminum alloys,
In addition, among non-metal materials, materials such as ceramics have been attracting attention. Among them, ceramics are excellent in mechanical properties such as abrasion resistance as characteristics, and meet the requirements of sliding members. Recently, a compressor incorporating a sliding member made of a ceramic material has been used.

[0003]

On the other hand, on the other hand, in ceramics, cast iron whose coefficient of linear expansion is widely adopted as a material for sliding members of this kind, and iron-based materials such as iron-based sintered alloys are used. It has the property of being small in comparison. Therefore, when ceramics is used as the material of the sliding member that causes the temperature of the sliding surface to rise to 100 ° C. or more during operation, a gap is generated due to the difference in the linear expansion coefficient between the members. ,
There is a drawback that the refrigerant in the compression chamber leaks from this gap, resulting in a decrease in compression capacity.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, prevent the occurrence of gaps due to the difference in thermal expansion between the sliding members, and at the same time, to improve the abrasion resistance of the sliding members. To provide a compressor with improved mechanical strength, durability and reliability.

[0005]

In order to achieve the above object, the present invention provides a sliding member of a compressor with an yttria (Y ₂
O ₃₎ a 3 to 8 (mol%) compounded partially stabilized zirconia _{(Y 2} O 3 -PSZ) is characterized in that it has formed a sintered body.

[0006]

According to the present invention, the partially stabilized zirconia of the material of the sliding member has a linear thermal expansion coefficient similar to that of iron unlike other ceramic materials, and the counterpart material is an iron-based material. In such a case, there is no gap in the fitting portion, so that reduction in compression capability is prevented. In addition, the advantages of the ceramic material are weight reduction and excellent wear resistance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. This example is an example in which the present invention is applied to a roller piston type compressor for an air conditioner,
FIG. 1 shows a cross section of the compression part. In this figure, reference numeral 1 indicates a closed casing. A cylinder 2 is fixed to the inner peripheral surface of the hermetic casing 1, and inside the cylinder 2, a roller 4 which is eccentrically rotated with the shaft 3 performs a cycle of intake and compression strokes. That is, the vane 5 is fitted in the cylinder 2 so as to be movable back and forth, and the vane 5 is elastically urged by the spring 6 and slidably contacts the roller 4 at its tip. Therefore, the vane 5 divides the cylinder chamber 7 into the expansion chamber 7a and the compression chamber 7b. The gas blown from the suction pipe 8 is compressed by the eccentric rotation of the roller 4 and is discharged from a discharge pipe (not shown). In the present embodiment, among the sliding members of the compressor, the vane 5 that slides on the outer peripheral surface of the cylinder 2 is
Yttria as described below _(Y 2 _{O 3)} a predetermined amount the partially stabilized zirconia _{(Y 2} O 3 -PSZ) is molded from a sintered body. That is, in this embodiment,
Zirconia fine powder with 3% (mol%) of yttria as a sintering aid evenly dispersed was used as a sintering material, and was pressed into a predetermined shape of the vane 5 at a high pressure, and then several thousand centigrades. It was fired at a high temperature to obtain a thermally stable product. Regarding the material of the cylinder 2 in which the vanes 5 are incorporated, taking into consideration the good compatibility with the sintered body of the vanes 5, iron-based materials such as iron-based castings, iron-based sintered materials, and steel Materials or materials obtained by subjecting these iron-based materials to surface treatment such as nitriding or carburizing are preferable.

Therefore, FIG. 2 shows the vane 5 of this embodiment.
And other conventional vanes made of other ceramic materials such as alumina, silicon nitride, silicon carbide, fracture toughness,
This is a comparison of linear thermal expansion coefficients. As can be seen from the data in this figure, the linear thermal expansion coefficient of the partially stabilized zirconia (Y ₂ O ₃ -PSZ) sintered body is higher than that of other ceramics, and the linear thermal expansion coefficient of iron (9 × 10 ⁻⁶ /
C)). Therefore, in the conventional vane,
When the cylinder of the mating material is an iron-based material, a gap is created in the fitting part due to the difference in the coefficient of linear thermal expansion,
There is a risk that the refrigerant may leak from this gap, leading to a reduction in compression capability. However, the vane 5 of this embodiment solves such an inconvenience. Further, the fracture toughness is also greatly improved compared to the conventional example, and it is considered that this is due to partial stabilization by the addition of yttria. This toughness enhancement is also related to the yttria blending ratio. Below 2 (mol%), the volume changes due to phase transformation (cubic to monoclinic) at high temperature during molding. , The microcracks are formed, some of the fractures occur, and the toughness deteriorates. On the other hand, when yttria exceeding 8 (mol%) is blended, the property approaches that of fully stabilized zirconia, and the fracture toughness drops sharply. A vane made of this material may be destroyed by jumping at startup. is there.

Next, a refrigerating capacity test was carried out in an actual machine equipped with a compressor incorporating the vane 5 of this embodiment, and the test result of the conventional vane compressor of iron-based material was set to 100 and other ceramic materials. A comparison with the results of a freezing test with a vane compressor is shown in FIG. From this figure, it can be seen that the present invention is expected to have improved capacity over the conventional compressor for vane made of ceramic material, and can achieve the same capacity as the compressor for vane made of iron-based material. Moreover, since the vane of partially stabilized zirconia takes advantage of the advantages of its ceramic material such as weight reduction and excellent wear resistance (in an abrasion test on an actual machine, an iron-based vane of 2 μm after operating for 5000 hours, In the example, it was 1 μm or less.),
The durability and reliability of the compressor are improved.

FIG. 4 shows the change in bending strength over time for a partially stabilized zirconia sintered body containing 3 (mol%) yttria at 250 ° C., with the sintered body particle size d = 0.
2, 0.4, 0.8, 1.0, 1.2 (Unit μ
The data is obtained for each of m).
As can be seen from this test result, when the particle size exceeds 1.0 μm, deterioration with time due to heat progresses rapidly, so it is selected as the material of the sliding member exposed to a temperature of 100 to 200 ° C. like a vane of a compressor. In that case, the particle size is preferably 0.8 μm or less. Although the embodiment of the roller piston type compressor has been described above, the present invention is not limited to the scope of this embodiment, and other sliding members such as rollers,
Of course, other types of compressors can be applied to sliding members such as Oldham rings.

[0011]

As is apparent from the above description, according to the present invention, the sliding member of the compressor is made to have the yttria (Y
Since it is formed of a partially stabilized zirconia (Y ₂ O ₃ -PSZ) sintered body containing 3 to 8 (mol%) of ₂ O ₃ ), it is possible to prevent the deterioration of the ability due to the difference in the coefficient of linear thermal expansion. It is possible to provide a compressor having excellent reliability and durability by strengthening the mechanical properties of the sliding member such as abrasion resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a compression unit in an embodiment in which the present invention is applied to a roller piston type compressor.

FIG. 2 is a diagram comparing fracture toughness and linear thermal expansion coefficient between an example of the present invention and a conventional example.

FIG. 3 is a diagram comparing the results of a freezing test using an actual machine for an example of the present invention and a conventional example.

FIG. 4 is a graph showing the test results obtained by changing the bending strength of a partially stabilized zirconia sintered body at high temperature with time in different particle diameters of the sintered body in the example of the present invention.

[Explanation of symbols]

 2 cylinder 3 shaft 4 roller 5 vane 7 compression chamber

Claims (1)

[Claims] 1. A sliding member of a compressor is made of yttria (Y ₂ O).
The _{3) 3~8} (mol%) compounded partially stabilized zirconia _{(Y 2} O 3 -PSZ) compressor, characterized in that formed in the sintered body.