Swash plate of swash plate type compressor

Details Swash plate of swash plate type compressor Swash plate of swash plate type compressor

2001-03-09

2003-04-01

Koehler, Robert R. (Department: 1775)

Stock material or miscellaneous articles

All metal or with adjacent metals

Composite; i.e., plural, adjacent, spatially distinct metal...

C428S621000, C428S634000, C428S639000, C428S640000, C428S643000, C428S644000, C428S650000, C428S653000, C428S654000, C428S674000, C428S676000, C428S698000, C428S908800, C428S937000

Reexamination Certificate

active

06541127

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a swash plate of a swash-plate type compressor. The present invention relates to such technical fields as a swash-plate type compressor, the sliding layer having, a composite structure, flame-spraying technique, aluminum-alloy sliding material and copper-alloy sliding material.
BACKGROUND TECHNIQUE
In the swash-plate type compressor, a swash-plate is rigidly secured obliquely to a rotary shaft or is secured obliquely to a rotary shaft in such a manner that its slanting angle is variable. The compression and expansion are carried out by means of rotating the swash-plate, which increases or decreases the volume of a partition space within a compressor, depending upon the rotation of the rotary shaft.
Such swash plate is caused to slide on a sliding member referred to as a shoe, and gas-tight sealing is attained between the both members. The cooling medium can therefore be compressed and expanded in the stated space.
A salient point in the sliding conditions of swash plate is that, during the initial operational period of compressor, the cooling medium reaches the sliding part between the swash plate and the shoe; thus the cooling medium has a rising effect on the lubricating oil which remains on the sliding part, with the result that the sliding condition is in a dry condition free of lubricating oil. The requirements for the sliding condition of the swash plate are therefore very severe.
The sliding properties, which are required for a swash-plate used under the condition described above, are seizure resistance, wear resistance, and like. Proposal have thus been made to add hard materials into the aluminum material for enhancing the wear resistance, to improve the material of the swash plate, and to subject an iron-based swash-plate to heat treatment for enhancing the hardness and hence wear-resistance.
The present applicant proposed in Japanese Unexamined Patent Publication No. SHO 51-36611 to bond sintered Cu material on the shoe in the case of an iron-based swash plate. That is, an iron-based swash plate was heretofore subjected to hardening treatment. However, when the material of the opposed member, i.e., the shoe, is an iron-based material, the sliding takes place between identical kinds of materials thereby incurring a problem that a seizure is liable to occur. Sintered copper alloy is used for the opposing material (shoe) opposed to an iron-based swash plate, so as to avoid the above mentioned problem.
In addition, it was also proposed to apply tin plating on the iron-based swash plate so as to avoid the sliding between identical kinds of materials and hence to enhance the seizure resistance. However, since the Sn plating applied on the iron based swash-plate is soft, there arises a problem of failure in wear resistance. In addition, a hard element added to the aluminum alloy enhances the wear resistance but results in a problem of failure in the seizure resistance.
In addition, it is proposed in European Patent Publication 071397A1 to provide a swash plate of a swash-plate type compressor with a surface layer, which is formed by such a flame-spraying that a part of the layer is not melted. Allegedly, the wear resistance of the flame sprayed copper-alloy is superior to that of the above mentioned conventional swash-plate.
Metal-ceramics composite material has been mainly investigated as metal-based composite material. Production methods are: press forming and then sintering a mixture powder of the copper-alloy and Al
2
O
3
powder (Japanese Patent No. 2854916); impregnating the ceramic carbon with Al alloy melt (Japanese Patent No. 2846635); and the like.
In the sliding materials, the clad material has a metal-metal composite structure.
The flame-spraying technique is illustrated in Journal of Japan Institute of Metals “Materia Japan” Vol. 33(1994), No.3. p 268-275, entitled “Recent Developments in Flame-Spraying Technique”. Production methods of a metal-ceramic based composite material are explained. The flame-spraying techniques are also illustrated in Tribologist Vol. 41 (1996), No. 11, pages 19-24.
Japanese Unexamined Patent Publication No. 9-122955 discloses a sliding bearing of the copper-aluminum alloy composite material referred to in the present invention in which the sliding bearing, a soft layer having hardness comparable to that of white metal, is dispersed in the aluminum-alloy matrix. The method for producing this composite material consists of: a first step of providing a flat sheet consisting of an aluminum-alloy material and having a backing metal; a second step of firmly bonding on the front surface of the flat sheet a soft material, such as Sn, Pb or white metal to 50-100 &mgr;m of thickness; a third step of locally irradiating laser beam on the above-mentioned flat sheet, with the firmly bonded soft metal, thereby dissolving the soft metal into the interior of the aluminum alloy; and a fourth step of bending the flat sheet to a semi-circular form; and, a fifth step of machine, finishing the laser-flame sprayed surface and then polishing the soft material, thereby exposing, in the polished part, the complex layer of the aluminum-alloy and the soft-alloy layer.
Among the copper alloys, the frequently used sliding alloy is a Cu—Pb based alloy, in which the added Pb improves the adhesion resistance and the seizure resistance. Since the wear resistance of copper alloy is poor, it is known to add a hard matter such as Fe
2
P into the copper alloy and to sinter it, as is proposed in U.S. Pat. No. 5,326,384 assigned to the present applicant. The conformability is, however, inevitably impaired by the addition of such hard matter.
The flame-spraying technique proposed in European patent publication 0713972A1 enables a part of the Cu—Pb alloy structure, particularly the Pb structure, to remain unmelted and hence the Pb phase is not coarsened. The wear resistance can thus be enhanced. However, since the wear resistance of the flame sprayed Cu—Pb alloy surface-layer is not satisfactory, so that the swash plate is locally worn. There arises occasionally such problems as lowering of air-conditioning capacity, generation of abnormal sound, abnormal vibration and the like.
However, it is difficult to harden the flame-sprayed copper alloy and hence to improve the wear resistance. That is, the hardening of copper alloy is broadly carried out usually by means of precipitation-hardening in the case of wrought alloy, such as rolled or drawn alloys. Since the flame-sprayed alloy is basically a cast alloy, the hardening relying on modification of the composition is difficult.
DISCLOSURE OF INVENTION
It is, therefore, an object of the present invention to improve wear resistance of a flame-sprayed copper-alloy,layer of a swash-plate type compressor.
The present invention provides a swash plate of a swash-plate type compressor, characterized in that a flame-sprayed surface layer, which comprises copper or a first copper-alloy having at least unmelted phase, and aluminum or a first aluminum alloy having at least melted phase are formed on at least a surface of the swash plate in sliding contact with a shoe.
The copper or copper alloy (collectively referred to as “the copper alloy” in this paragraph) and aluminum or aluminum alloy (collectively referred to as “the aluminum alloy” in this paragraph) are rendered to the sliding layer of a swash plate having a composite structure. For this purpose, a part of these alloys should be melted and play a role of binder. From another point of view, for example, Pb of a Cu—Pb alloy and Si of an Al—Si alloy impair the properties of the matrix of the other alloy, so that no useful composite structure is obtained. The complete melting of the copper alloy and aluminum alloy should, thus, be prevented.
In the present invention, the binder effect for forming the composite material can be realized when at least the aluminum-alloy is melted. Copper and aluminum inherently exhibit good compatibility and are appropriate for bonding.
Examples of copper alloy and aluminum alloy are mainly described he

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