Swash-plate of swash-plate type compressor

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

1999-11-29

2002-02-05

Jones, Deborah (Department: 1775)

Stock material or miscellaneous articles

All metal or with adjacent metals

Having metal particles

C428S564000, C428S568000, C428S569000, C428S652000, C428S653000, C428S654000, C428S937000, C075S231000, C075S249000, C092S071000

Reexamination Certificate

active

06344280

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a swash plate of a swash-plate type compressor. More particularly, the present invent ion relates to a surface-treating technique for outstandingly improving the sliding properties of a swash plate which consists of iron- based or aluminum-based material.
BACKGROUND TECHNIQUE
In the swash-plate type compressor, the swash plate
2
is rigidly secured obliquely to a rotary shaft
1
as shown in FIG.
1
. Alternatively, the swash plate 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 partition space within a compressor, depending upon the rotation of the rotary shaft. Such swash plate is caused to slide on a shielding member referred to as a shoe
3
. Gas-tight sealing between the swash plate and the shoe enables the compression and expansion of the cooling medium in the stated space.
4
is a ball.
A noteworthy point in the sliding conditions of a swash-plate is that, during the initial operational period of a compressor, the cooling medium reaches the sliding part prior to the lubricating oil reaching the sliding part between the swash plate and the shoe; thus the cooling medium has a rinsing effect on the lubricating oil which remains on the sliding part, with the result that the sliding condition is a dry condition free of lubricating oil. The sliding condition requirements of the swash plate are therefore very severe.
The sliding properties, which are required for a swash-plate used under the conditions described above, are seizure resistance, wear resistance, and the like. Proposals have thus been made to add hard matters 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. In addition, the following surface treating methods are also proposed.
One of the present applicants proposed in Japanese Unexamined Patent Publication No. Sho51-36611 to bond the 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 involving a problem that 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. Since the tin plating applied on an iron-based swash-plate is soft, a problem that arises is insufficient wear-resistance.
The eutectic or hyper-eutectic Al—Si based aluminum alloy, which is produced by casting or forging, exhibits excellent wear-resistance. Its production becomes, however, difficult, when the Si content exceeds 15%. The wear resistance of this alloy is, therefore, limited by the Si amount.
Recently, powder-metallurgy products utilizing a melt-quenched powder (for example Japanese Patent Publication No. 2535789) are proposed.
Since the Si content is very high, as much as from 14 to 30%, the wear resistance is greatly enhanced. However, the resultant alloy must be subjected to such working as hot-press followed by hot-extrusion. Therefore, in order to produce relatively large-sized parts, such as a swash plate, investment in installation of large-capacity equipment such as a press and an extruder is necessary. Cost competitiveness, therefore, is lowered.
DISCLOSURE OF INVENTION
It is, therefore, an object of the present invention to provide on the surface of an iron or aluminum-based swash-plate a surface-layer having improved both seizure-resistance and wear-resistance, thereby enhancing the performance and reliability of a swash-plate type compressor.
The present inventors carried out, therefore, research so that, the Al—Si aluminum-alloys based sliding material in a eutectic region or a hyper-eutectic region can be formed as a sliding layer on the surface of a swash plate by means of a simple method; and, considerably improved properties over those of the conventional various sliding layers are demonstrated.
The present inventors energetically carried out experiments and discovered that the flame-sprayed Al—Si based aluminum alloys in a eutectic region or a hyper-eutectic region exhibits improved adhesiveness with a substrate; and, the Si particles are refined. The present invention was thus completed.
Namely, the present first invention is a swash plate of a swash-plate type compressor, characterized in that a flame-sprayed layer deposited on the substrate contains from 12 to 60% by weight of Si, the balance being essentially Al, and has the granular Si particles dispersed in the matrix thereof. The present second invention is a swash plate of a swash-plate type compressor, characterized in that a flame-sprayed layer deposited on the substrate contains from 12 to 60% by weight of Si, from 0.1 to 30% by weight of Sn, the balance being essentially Al, and has the granular Si particles and Sn phase dispersed in the matrix thereof.
The flame-spraying (spraying) is based on the definition in the Glossary Dictionary of JIS Industrial Terms, 4 th edition, page 1946 and indicates that “material is converted to molten or half-molten state by a heat source and is blown onto a substrate to form a film.” More specifically, the “material” is aluminum-alloy or its raw material, for example, Al and Si powder. The half-molten state indicates such a solid-liquid coexisting state as is realized in a high-Si Al—Si alloy, i.e., a material having high melting-point. The half-molten state indicates that a portion of the powder does not melt, as is explained hereinbelow.
The present invention is explained in detail hereinafter. The percentage is weight % unless otherwise specified.
EMBODIMENTS OF INVENTION
According to the Al—Si based alloy of the present first invention, Si in granular form is dispersed in the aluminum matrix finely and in a large amount. Thus, Si enhances the hardness and hence wear-resistance of the alloy. In addition, the granular Si particles disperse finely in a large amount and suppress the adhesion between the aluminum matrix and a shoe and hence seizure due to such adhesion.
EP 0713972A1 filed by the present applicants provides a detailed explanation of the flame-sprayed copper alloy by referring to an example of Cu—Pb alloy. The rapid cooling and solidification of molten particles is common in the Al—alloy example. One feature of the flame-sprayed Al—Si alloy is that an additive element (Si) has a higher melting point than that of the matrix element (Al). As a result, Si in granular form is finely dispersed in the aluminum matrix in a large amount. Thus, the effect is obtained such that Si enhances the hardness and hence wear-resistance of the alloy.
In the present invention, the granular Si particles do not have the same shape as seen in the primary Si of the conventional melted alloy or the Si particles of the rolled alloy. They have a one-directional, lengthwise property. Rather, the granular Si particles of the present invention have spheroidal, nodular, polygonal or irregular shapes, not classified as the former three shapes, and have almost the same size in any direction. Furthermore, a noteworthy distinction between the primary Si and eutectic Si seen in the conventional melted alloys disappears in the case of the present invention.
When the Si content of the aluminum-alloy according to the present invention is less than 12%, the enhancement effects of wear resistance and seizure resistance are slight. On the other hand, when the Si content exceeds 60%, the strength so drastically lowers as to impair wear resistance. A

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