JP2005256062A - Bearing for compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sintered alloy bearing which is excellent in wear resistance, is low in aggressiveness to a mating material and is low in price and is particularly suitable as a compressor performing compression of alternatives for fluorocarbon having problems in lubricity. <P>SOLUTION: The bearing for the compressor is formed by the sintered alloy dispersed with 0.3 to 3%, by weight ratio, rigid particles of Hv 800 to 1,100 in a pearlite base. The rigid particles are preferably Fe-Mo particles, and above all, the particles of 20 to 100 μm in average grain size and further the bearing integrally forming the housing of the compressor is preferably and previously subjected to a sealing treatment of sintering vacancies. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a compressor bearing formed of a sintered alloy, and more particularly, to a compressor bearing having a high resistance to wear by suppressing the opponent attack.

  One known positive displacement compressor is shown in FIG. In this compressor, a rotor 3 having a rotating shaft 2 is housed in a casing 1 and the rotor 3 having a vane 4 pressed against an outer peripheral surface by a spring 5 is rotated around the rotating shaft 2 supported by a bearing. . The rotating shaft 2 is in an eccentric position from the center of the rotor 3, and the rotor 3 rotates while sliding on the inner peripheral surface of the casing 1 around the rotating shaft 2, and is thereby sucked from the suction port 6. The compressed fluid is compressed and discharged from the discharge port 7. FIG. 3 is an exploded perspective view of the entire compressor. The components of the compressor shown in FIG. 2 are assembled into the main case 11 with both ends of the rotating shaft 2 supported by the housing integrated bearing 10.

  This type of compressor is often used to compress a refrigerant for air conditioning or freezing and refrigeration.

  By the way, as a bearing material of the compressor for refrigerants, so far, Fe—Cu—C-based sintered alloy, specifically, copper: 1.0 to 3.0% by weight ratio, carbon: 0.5 to A sintered alloy containing 0.9% and the balance being iron and inevitable impurities was used. However, this conventional material has the following problems.

  As an alternative to CFCs, alternative CFCs that do not contain chlorine (for example, ester-based refrigerants) have started to be used. However, CFC-free refrigerants are inferior in lubricity compared to CFCs and are made of the aforementioned conventional materials. Bearings are extremely worn and cannot be used.

  Moreover, the following patent document 1 has a first phase mainly composed of Fe in which fine carbides of 10 μm or less are precipitated as a material for a compressor part that meets the demand for improved wear resistance, and Fe as a main component. An iron-based sintered alloy material mainly composed of an iron-based matrix structure, which is composed of a mixed structure with a softer second phase than the first phase is disclosed.

However, there is a concern that this material, especially a material in which hard particles are dispersed in an iron base matrix structure by 1 to 20% in area ratio, is too counterattack when it is applied to a bearing and wears the rotary shaft of the compressor. The
Japanese Patent Laid-Open No. 11-140603

  Therefore, attention has been paid to Fe—Ni—Cu—Mo—C based sintered alloys frequently used in machine parts as bearing materials to replace conventional Fe—Cu—C based materials. This material has a hardness of about Hv 800 to 1050, and can also be used for a bearing used in a situation where the lubricity is poor.

  However, this Fe—Ni—Cu—Mo—C based sintered alloy has a disadvantage that the raw material cost is high.

  When the bearings and the rotating shaft are worn, the clearance between the two becomes large and the rotor rattles. Thereby, the sealing performance of the compression chamber is lowered, the compression efficiency of the compressor is lowered, and noise during operation is also increased.

  Accordingly, the bearing for the compressor is required to have excellent wear resistance and low opponent attack. In addition, mass-produced compressor bearings are particularly required to be inexpensive.

  This invention makes it a subject to implement | achieve and provide the bearing for compressors made from the sintered alloy which satisfy | fills said three requirements simultaneously.

  In order to solve the above-described problems, in the present invention, a compressor bearing is formed of a sintered alloy in which hard particles of Hv 800 to 1100 are dispersed in a pearlite matrix by 0.3 to 3% by weight.

  The hard particles are preferably Fe-Mo particles. The hard particles preferably have an average particle size of about 20 μm to 100 μm.

  Further, this bearing may be formed integrally with the housing of the compressor, and the housing-integrated bearing may be subjected to a sealing hole sealing process.

  In the sintered alloy used in the present invention, hard particles of Hv 800 or more are dispersed in a pearlite matrix by 0.3 to 3% by weight, and the hard particles improve the wear resistance of the bearing.

  Further, the hard particles dispersed in the pearlite base have a Hv of 1100 or less, and the hard particles are dispersed on the sliding surface of the bearing at an area ratio of 0.3 to 3% or less. Does not rise extremely.

  As the rotation shaft of the compressor, a casting having a Hv of about 300 to 400 is generally used. In order to suppress the aggressiveness against the rotating shaft, it is important that the hardness of the hard particles appearing on the sliding surface of the bearing is not too high and the amount of the hard particles is not too large.

  The sintered alloy material of the above-mentioned patent document 1 is said to be able to disperse hard particles of Hv 700-1500 in an area ratio of 1-20%, but compared with the hard particles adopted in the present invention, Both the upper limit of hardness and the upper limit of dispersion amount are too large.

  Moreover, the sintered alloy material of patent document 1 is in the situation where the 1st phase and 2nd phase from which hardness differs draws a mottled pattern, and the surface is easy to attack an other party.

  On the other hand, the sintered alloy constituting the bearing of the present invention is in a state in which hard particles of Hv 800 to 1100 are dispersed at a ratio of 3% or less in a fingerprint-like pearlite structure in which ferrite and cementite are deposited in layers. . Therefore, even if the sliding partner is a casting of about Hv 300 to 400, the opponent is not significantly attacked.

  Furthermore, this sintered alloy does not contain an expensive metal such as Ni, so that an increase in the cost of the bearing can be suppressed.

  The hard particles employed in the present invention are particularly suitable Fe-Mo particles that are inexpensive and have an appropriate hardness.

  In addition, when the average particle diameter is 20 μm or more, the hard particles hardly diffuse during the sintering of the bearing, and the effect of improving the wear resistance is easily improved. In addition, when the average particle size is 100 μm or less, the cutting of the bearing is not adversely affected. Therefore, it is preferable to use those having an average particle size of about 20 μm to 100 μm.

  Further, since the bearing formed integrally with the compressor housing is required to be airtight, it is preferable that the bearing is subjected to sealing treatment. The sealing can be performed by a method such as treatment with superheated steam after sintering.

  Hereinafter, embodiments of the bearing of the present invention will be described. FIG. 1 shows a housing-integrated bearing 10 attached to the end of the casing 1 of the compressor shown in FIGS.

  In the housing-integrated bearing 10, a bearing 9 is formed integrally with a front housing 8 that seals a casing end, and the bearing 9 supports the rotary shaft 2 shown in FIGS.

  The exemplary housing-integrated bearing 10 has a weight ratio of C: 0.5 to 1.2% (more preferably 0.7 to 1.1%), Cu: 1.0 to 5.0% (more preferably). Is made of a sintered alloy in which Fe-Mo particles having an average particle size of 20 μm to 100 μm are dispersed in an amount of 0.3% to 3% on the pearlite base of the remaining Fe and inevitable impurities. Has been. Further, after the sintering, an oxidation sealing treatment with steam is performed, and there are no remarkably porous portions on each surface portion.

  The sealing treatment can be performed by a method of infiltrating a low melting point metal or the like, but the oxidation treatment with superheated steam is easier to implement and is economically superior.

  Note that the present invention can also be applied to a compressor bearing that compresses a fluid other than an alternative chlorofluorocarbon.

  More detailed examples are given below.

  The housing-integrated type shown in FIG. 1 is a sintered alloy in which Fe—Mo particles are dispersed in a pearlite matrix having a composition of C: 1.0%, Cu: 2.0%, the balance Fe and inevitable impurities. A bearing was produced. The amount of Fe—Mo particles added to the sintered alloy of the material was changed as shown in Table 1. Further, the Fe—Mo particles having an average particle diameter of 50 μm were used.

  After mixing the raw materials mix | blended in said ratio and press-molding, it sintered for 10 to 25 minutes at the temperature of 1100-1150 degreeC in non-oxidizing gas atmosphere.

  Furthermore, after sintering, steam oxidation sealing treatment was performed at a temperature of 560 to 600 ° C. for 80 to 120 minutes.

The housing-integrated bearing 10 thus obtained has a density of each part of 6.6 g / cm ³ or more. In addition, an oxide film of Fe ₃ O ₄ is formed on the surface by the steam oxidation sealing treatment, so that there is no extremely porous portion, and the airtightness required for the housing is ensured.

  The housing integrated bearing 10 has a hardness of Hv 800 to 1100 and a tensile strength of 300 MPa or more.

  Next, a wear seizure test was performed on this prototype. The counterpart material is a casting (FC250) of Hv 300 to 400. Abrasion resistance and opponent attack were evaluated by rubbing against this counterpart material.

  The results are also shown in Table 1. Table 1 shows that the evaluation result was very good by ◎, that the evaluation result was good by ○, and that the evaluation result was bad by ×.

  As can be seen from the test results, a bearing formed of a sintered alloy having an amount of Fe-Mo particles of 0.2% by weight has a low counterpart attack but a poor wear resistance.

  Further, a bearing formed of a sintered alloy having an amount of Fe—Mo particles of 5% by weight or more satisfies the wear resistance but has a high opponent attack property and does not provide a satisfactory result.

  On the other hand, a bearing formed of a sintered alloy in which the amount of Fe—Mo particles is 0.3 wt%, 0.5 wt%, 1.0 wt%, 2.0 wt%, and 3.0 wt%. Satisfies both the requirements of wear resistance and opponent aggression.

  Further, the sintered alloy used here is obtained by adding inexpensive Fe-Mo particles to an Fe-Cu-C-based inexpensive material, thereby avoiding an increase in the cost of the bearing.

The perspective view which shows an example of the bearing of this invention Sectional drawing which simplifies and shows the principal part of an example of a compressor Exploded perspective view showing an overview of an example of a positive displacement compressor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Rotating shaft 3 Rotor 4 Vane 5 Spring 6 Suction port 7 Discharge port 8 Front housing 9 Bearing 10 Housing-integrated bearing 11 Main case

Claims (4)

  A compressor bearing formed of a sintered alloy in which hard particles of Hv 800 to 1100 are dispersed in a pearlite base by 0.3 to 3% by weight.   The compressor bearing according to claim 1, wherein the hard particles are Fe—Mo particles.   The compressor bearing according to claim 1, wherein the hard particles have an average particle diameter of 20 μm to 100 μm.   The compressor bearing according to any one of claims 1 to 3, wherein the compressor bearing is formed integrally with the compressor housing and subjected to sealing of the sintered voids.

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