The present invention relates to a shoe, and more particularly, to an improvement in a shoe used for a swash plate compressor.
Hemispherical shoes used for swash plate compressors have been conventionally known. The hemispherical shoe includes a spherical portion in sliding contact with a hemispherical concave portion on a piston side, and an end surface portion in sliding contact with a swash plate (for example, Patent Literatures 1 to 4).
Recently, there has been a need for swash plate compressors for automobiles to be reduced in cost, be compatible with a new refrigerant, or the like. The swash plate compressors are particularly required to be more efficient.
To this end, the following improvements in the shoe have been proposed respectively in Patent Literatures 1 to 4. That is, in Patent Literature 1, the surface roughness of a sliding portion and the surface roughness of a non-sliding portion in the spherical portion of the hemispherical shoe are made different from each other. Patent Literature 2 proposes that the spherical portion has a stepped tapered surface. Also, Patent Literature 3 proposes that the outer peripheral edge of the hemispherical shoe is largely removed over the entire circumference to thereby form a cylindrical portion. Furthermore, Patent Literature 4 proposes that an oil groove having a spiral shape or the like is formed in the spherical portion of the hemispherical shoe.
In the swash plate compressor, a lubricant oil is mixed in a refrigerant in a circulation circuit and is thereby also circulated, so that the lubricant oil is fed to the sliding portion between the shoe and each of the piston and the swash plate. However, the amount of lubricant oil enclosed within the refrigerant circulation circuit has been reduced in recent years. Thus, the sliding portion between the shoe and each of the piston and the swash plate suffers poor lubricant conditions.
Especially when the swash plate compressor is started, the lubricant oil is not mixed in the refrigerant in the circulation circuit. Thus, even when the refrigerant is circulated in the circulation circuit, the lubricant oil cannot be sufficiently fed to the sliding portion between the shoe and each of the piston and the swash plate through the refrigerant. Seizure thereby easily occurs in the sliding portion between the shoe and each of the piston and the swash plate in a conventional case when the swash plate compressor is started, so that such a problem is caused that abnormal sounds and noises are generated due to the abnormal wear of the sliding portion.
In view of the aforementioned circumstances, the present invention provides a shoe including a spherical portion in sliding contact with a hemispherical concave portion of a first movable member, an end surface portion in sliding contact with a flat surface of a second movable member, and a cylindrical portion formed between the spherical portion and the end surface portion,
wherein a groove and/or a concave portion is provided in an outer peripheral surface of the cylindrical portion, and a lubricant oil is held in the groove and/or the concave portion.
With the above configuration, in a case where the shoe is used for a swash plate compressor, a lubricant oil separated from a refrigerant is held in the oil groove or the concave portion of the shoe when the swash plate compressor is not started. Therefore, even when the lubricant oil is not mixed in the refrigerant at the time of starting the swash plate compressor, the lubricant oil held in the oil groove or the concave portion is fed to the spherical portion and the end surface portion of the shoe, which are the sliding portions. Accordingly, a shoe having a good lubricity, even when the swash plate compressor is started, can be provided.
In the following, the present invention will be described based on embodiments shown in the drawings.
The swash plate 3 is obliquely fixed to the rotating shaft 2, or the inclination angle of the swash plate 3 can be changed. The swash plate 3 is held by the two shoes 5 in each of the pistons 4. A predetermined coating such as a thermally sprayed layer, a plated layer, and a resin coating is applied on the flat surfaces of the swash plate 3 in sliding contact with the shoes 5. Note that the configuration of the swash plate 3 applicable to the present invention is not limited to that described above, and various conventionally known swash plates can be used.
Sliding surfaces 4a having hemispherical concave portions are formed so as to face each other in the piston 4. The shoes 5 convert the rotation of the swash plate 3 into the reciprocating motion of the piston 4 while swinging and sliding on the sliding surfaces 4a.
The configuration of the swash plate compressor 1 as described above has been conventionally well known, and a further detailed description is omitted.
The shoe 5 according to a present embodiment includes a spherical portion 5A in sliding contact with the sliding surface 4a of the piston 4, an end surface portion 5B in sliding contact with the flat surface of the swash plate 3, and a circular cylindrical portion 5C formed between the spherical portion 5A and the end surface portion 5B as shown in
A releasing portion 5D having a flat surface so as not to contact the sliding surface 4a on the piston 4 side is formed on the top of the spherical portion 5A. A lubricant oil is thereby allowed to flow into a space formed between the sliding surface 4a and the releasing portion 5D.
The end surface portion 5B defines a sliding surface in sliding contact with the swash plate 3, and has a crowned shape that slightly bulges about several μm at its center portion toward the swash plate 3 from the outer peripheral portion. The lubricant oil is thereby easily drawn into a space between the end surface portion 5B and the swash plate 3. A chamfered portion 5E is formed on the outer peripheral edge of the end surface portion 5B.
Next, the cylindrical portion 5C of the shoe 5 has a circular cylindrical shape with a constant outer diameter over the entire axial length. The axial length of the cylindrical portion 5C is set to be about twice as large as the axial length of the spherical portion 5A. The outer peripheral surface of the circular cylindrical portion 5C is not in sliding contact with the swash plate 3 and the sliding surface 4a of the piston 4. In the present embodiment, a plurality of linear oil grooves 5F are formed in the outer peripheral surface of the cylindrical portion 5.
The oil grooves 5F are circumferentially formed in the outer peripheral surface of the cylindrical portion 5C at equal pitches so as to be inclined 45 degrees to an axis C of the shoe 5. One end of each of the oil grooves 5F reaches the spherical portion 5A, and the other end of each of the oil grooves 5F reaches the chamfered portion 5E, that is, the outer peripheral edge of the end surface portion 5B.
The sectional shape of the oil groove 5F is a horizontally long rectangle which has a constant depth and has a larger width than the depth as shown in
As described above, the plurality of oil grooves 5F are formed in the outer peripheral surface of the cylindrical portion 5C from the end surface portion 5B to the spherical portion 5A in the shoe 5 according to the present embodiment. In the present embodiment, the oil grooves 5F are formed in the outer peripheral surface of the cylindrical portion 5C by knurling, turning, etching or the like.
With the shoe 5 according to the present embodiment, the retention of the lubricant oil is improved in comparison with the conventional shoe described above, so that better lubricity is obtained.
The operation will be described in detail. When a refrigerant including the lubricant oil axially flows around the outer peripheral surface of the cylindrical portion 5C, the lubricant oil included in the refrigerant enters each of the oil grooves 5F of the cylindrical portion 5C, and is captured therein to be easily separated from the refrigerant as shown in
Therefore, when the swash plate compressor 1 is not started, that is, when the refrigerant is not circulated in a circulation circuit, the lubricant oil separated from the refrigerant is held in each of the oil grooves 5F. When the swash plate compressor 1 is started, the lubricant oil is not mixed in the refrigerant. However, since the lubricant oil is held in each of the oil grooves 5F of the shoe 5 in advance, the lubricant oil is fed from each of the oil grooves 5F to the spherical portion 5A and the end surface portion 5B, which are sliding portions, when the shoe 5 slides. In other words, the lubricant oil held in the plurality of oil grooves 5F is fed to the spherical portion 5A and the end surface portion 5B, which are the sliding portions, when the swash plate compressor 1 is started, so that the shoe 5 having good lubricity can be provided. Furthermore, since the cylindrical portion 5C is formed in the shoe 5 of the present embodiment, the shoe 5 itself is reduced in weight in comparison with the conventional hemispherical shoe.
Therefore, by using the shoe 5 of the present embodiment, a swash plate compressor 1 capable of suppressing the occurrence of seizure and abnormal sounds in the sliding portion between the shoe 5 and each of the swash plate 3 and the sliding surface 4a, and having a high durability and efficiency can be provided.
Next,
Next, in
Next, in
Next, in
The shoe 5 in each of the embodiments shown in
Although one end of the oil groove 5F reaches the spherical portion 5A and the other end of the oil groove 5F reaches the end surface portion 5B in the shoe 5 in each of the embodiments shown in
Furthermore, in the shoe 5 in the embodiment shown in
The same operation and effect as those of the first embodiment in
The sectional shape and arrangement density of the oil grooves 5F in each of the aforementioned embodiments may be changed as shown in
Next,
Also, in
The shoe 5 where the plurality of concave portions 5G are formed in the outer peripheral surface of the cylindrical portion 5C can also produce the same operation and effect as those of the aforementioned first embodiment.
Next,
To be more specific, in
Also, in
Moreover, in
The shoe 5 in each of the embodiments shown in
Although one end of the oil groove 5F reaches the spherical portion 5A and the other end of the oil groove 5F reaches the end surface portion 5B in the shoe 5 in each of the embodiments shown in
The flange portion 5H may be also provided projecting on the outer peripheral edge of the end surface portion 5B in the shoe 5 according to the embodiment shown in each of
Furthermore, grid-like oil grooves may be also provided in the outer peripheral surface of the cylindrical portion 5C instead of the linear oil grooves 5F in each of the aforementioned embodiments. Alternatively, both the oil grooves 5F and the concave portions 5G may be provided in the outer peripheral surface of the cylindrical portion 5C.
Number | Date | Country | Kind |
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2009-129223 | May 2009 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2009/070464 | 12/7/2009 | WO | 00 | 8/5/2010 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2010/137194 | 12/2/2010 | WO | A |
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Number | Date | Country |
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10 2006 008 437 | Oct 2007 | DE |
57-76281 | May 1982 | JP |
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11-22640 | Jan 1999 | JP |
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Entry |
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JP2001-003858—Full machine translation of the applicant submitted prior art. |
JP11-050959—Full machine translation of the applicant submitted prior art. |
Application No. KR1020050051626, patent document No. KR100679863—English abstract translation. |
KR 100679863—Machine translation from Korean to English of Claims and description from KIPRIS. 2007. |
JP2008138545A English machine translation from JPO. 2008. |
Form PCT/ISA/210 dated Feb. 16, 2010 (3 pages). |
Form PCT/ISA/220 dated Feb. 16, 2010 (4 pages). |
Form PCT/ISA/237 dated Feb. 16, 2010 (4 pages). |
Korean Office Action dated Apr. 24, 2012, with English translation of main section thereof. |
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Number | Date | Country | |
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20110107908 A1 | May 2011 | US |