Expansible chamber devices – With lubricating means – Piston has lubricant retaining or conducting means
Reexamination Certificate
1999-03-25
2001-04-17
Look, Edward K. (Department: 3745)
Expansible chamber devices
With lubricating means
Piston has lubricant retaining or conducting means
C092S186000, C092S237000
Reexamination Certificate
active
06216584
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates in general to a piston and more particularly to a piston suitable for a compressor such as a swash plate type compressor.
A piston of the type is disclosed in Japanese Patent Unexamined Publication No. 9-105380/1997, which will be shown in
FIG. 3
of the attached drawing. The piston is indicated by reference numeral
8
in FIG.
3
and has a head portion
81
of a hollow structure and a shoe receiver
84
.
The piston shown in
FIG. 3
has a hollow head portion
81
and, therefore, has an advantage that it is light weighed. However, in an integral formation of the piston by casting, it is almost impossible to form the head portion in a hollow structure. Thus, the piston is formed by a casting method by dividing the entire structure into two parts and then the two parts should be coupled together by welding. This results in a substantial increase in production cost.
Another piston of the type is disclosed in Japanese Patent Application No. 9-126899 earlier filed by the present applicant (assignee), which is shown in
FIG. 4
of the drawing. The piston
8
of
FIG. 4
has a head portion
81
, a shell or barrel portion
82
connected with the head portion
81
, and a shoe receiving portion
84
. The barrel portion
82
has a U-shaped sectional shape at a surface intersecting at right angles to a reciprocal moving direction of the piston
8
.
The piston of
FIG. 4
, on the other hand, has solved the problem of the piston of FIG.
3
. Since the head portion
81
of
FIG. 4
is of a solid structure, the barrel portion
82
having a U-shaped sectional shape, it can be produced integrally or entirely by casting. Accordingly, the production cost can be reduced relative to the piston of FIG.
3
. However, in the piston of
FIG. 4
, when the piston
8
is slidably inserted into a cylinder bore (not shown), a deviation or offset of the piston
8
in the direction intersecting at right angles to a center of the cylinder bore can not be restricted by the barrel portion
82
and, therefore, it is likely that an opening side of the barrel is abnormally worn out, resulting in considerable reduction of durability.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a new and improved piston which permits reduction of cost and weight and has a considerable durability.
It is another object of the present invention to provide a compressor using the piston.
Other objects of the present invention will become clear as the description proceeds.
According to an aspect of the present invention, there is provided a piston for being slidably inserted into a cylinder bore defined by a cylindrical surface extending in a predetermined direction. The piston comprises a head portion extending perpendicular to the predetermined direction and having an outer circumferential portion which is close to the cylindrical surface when the piston is inserted in the cylinder bore, and a barrel portion connected to the head portion. In the piston, the barrel portion comprises at least three wall portions which are extended from the outer circumferential portion in the predetermined direction and arranged in a circumferential direction to form a substantially cylindrical shape in cooperation with one another.
According to another aspect of the present invention, there is provided a piston slidably inserted into a cylinder bore in a cylinder block. The piston comprises a head portion having an outer circumferential surface entirely slidably contacted with an inner circumferential surface of the cylinder bore, and a barrel portion connected with, and extending from, the head portion, and having an outer circumferential surface consisted with at least three circumferential wall portions extending along the slidable movement direction of the piston. In the piston, the at least three circumferential wall portions are located at a position where the barrel portion is unable to move in a direction perpendicular to the center of the cylinder bore.
According to still another aspect of the present invention, there is provided a compressor which comprises a cylinder block having a cylinder bore extending in a predetermined direction, a piston mentioned above and slidably inserted in the cylinder bore, and means coupled to the piston for making the piston be reciprocally moved along the cylinder bore in the predetermined direction.
REFERENCES:
patent: 4132510 (1979-01-01), Takahashi
patent: 4373876 (1983-02-01), Nemoto
patent: 4638725 (1987-01-01), Ripberger et al.
patent: 4697992 (1987-10-01), Hatakeyama et al.
patent: 5630353 (1997-05-01), Mittlefehldt et al.
patent: 5765464 (1998-06-01), Morita
patent: 5899135 (1999-05-01), Kanou et al.
patent: 0780572 (1997-06-01), None
patent: 9105380 (1997-04-01), None
Baker & Botts L.L.P.
Lazo Thomas E.
Look Edward K.
Sanden Corporation
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