Expansible chamber devices – Relatively movable working members – Interconnected with common rotatable shaft
Reexamination Certificate
2000-09-26
2002-07-09
Look, Edward K. (Department: 3745)
Expansible chamber devices
Relatively movable working members
Interconnected with common rotatable shaft
C092S248000
Reexamination Certificate
active
06415705
ABSTRACT:
This application is based on Japanese Patent Application No. 11-275706 filed Sep. 29, 1999, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a piston for a swash plate type compressor, and more particularly to such a piston whose head portion slidably fitted in an appropriate cylinder bore is hollow and cylindrical.
2. Discussion of the Related Art
Since such a piston used for a compressor is reciprocated within a cylinder bore, it is desirable to reduce the weight of the piston. In particular, the reduction of the weight of the piston is desirable when the piston is used for a swash plate type compressor, especially where the swash plate type compressor is of a variable capacity type. As the swash plate type compressor adapted to compress a refrigerant gas for an air conditioning system of an automotive vehicle, there has been recently used the variable capacity type swash plate compressor whose discharge capacity is adjustable by controlling an angle of inclination of the swash plate with respect to its rotation axis. When the piston is used for this type of compressor, it is particularly required to reduce its weight. The swash plate type compressor for the automotive vehicle is generally required to be rotated at a high speed for satisfying a need for reduction of its size. In view of this, it is required to reduce the weight of the piston. Where the variable capacity type swash plate compressor is adapted to adjust the inclination angle of the swash plate based on a difference between a pressure in a pressurizing chamber and a pressure in a crank chamber, the reduction of the weight of the piston is essential for achieving a stable adjustment of the inclination angle of the swash plate and reduction of the operating noise of the compressor.
JP-A-10-159725 discloses a swash plate type compressor piston having a hollow cylindrical head portion. In the piston disclosed in this publication, a hollow cylindrical member is closed at its open end by a closure member, so at to provide the hollow cylindrical head portion. The piston thus produced has a reduced weight. The hollow cylindrical member and the closure member of this piston are both formed of an aluminum material.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a swash plate type compressor piston having an improved structure for a further reduction of its weight.
The object indicated above may be achieved according to any one of the following forms or modes of the present invention, each of which is numbered like the appended claims and depend from the other form or forms, where appropriate, to indicate and clarify possible combinations of technical features of the present invention, for easier understanding of the invention. It is to be understood that the present invention is not limited to the technical features and their combinations described below. It is also to be understood that any technical feature described below in combination with other technical features may be a subject matter of the present invention, independently of those other technical features.
(1) A piston for a swash plate type compressor including a hollow cylindrical head portion and an engaging portion which engages a swash plate through a pair of shoes such that the shoes are held in contact with opposite surfaces of the swash plate at a radially outer portion of the swash plate, wherein the engaging portion is formed of a material which is different from that of an end section of the hollow cylindrical head portion, which end section is located on the side remote from the engaging portion.
Since the shoes are slidably received in part-spherical recesses formed in the engaging portion, the engaging portion is required to exhibit a sufficiently high degree of wear resistance, whereas the end section of the hollow cylindrical head portion, which end section is opposite to the engaging portion and partially defines a pressurizing chamber of the compressor, is required to exhibit a sufficiently high degree of strength rather than a high degree of wear-resistance. In other words, the engaging portion is required to be formed of a relatively expensive material to achieve the required wear resistance, while the end section of the head portion can be formed of a relatively inexpensive material. By using different materials for the engaging portion and the end section of the head portion, the piston can be produced at a reduced cost. In general, the outer circumferential surface of the head portion is coated with a wear-resistant synthetic resin film. In this case, the cylindrical wall of the head portion need not be formed of an expensive wear-resistant material, resulting in a further reduced cost of manufacture of the piston. An aluminum alloy containing not smaller than 5 wt. % of silicon is known as a wear-resistant material. This aluminum alloy is more difficult to be forged than an aluminum alloy whose silicon content is smaller than 5 wt. %. In view of this, if only a portion of the piston which constitutes the engaging portion which is required to have a high degree of wear resistance is formed of the wear-resistant aluminum alloy whose silicon content is relatively large, the other portion of the piston can be easily formed by forging, using the aluminum alloy whose silicon content is relatively small. Accordingly, the cost of manufacture of the piston is reduced.
(2) A piston for a swash plate type compressor having a swash plate, including a hollow cylindrical head portion and an engaging portion which engages the swash plate through a pair of shoes such that the shoes are held in contact with opposite surfaces of the swash plate at a radially outer portion of the swash plate, wherein the hollow cylindrical head portion includes a hollow cylindrical body portion having an open end on the side remote from the engaging portion and a closed end on the side of the engaging portion, the engaging portion and the hollow cylindrical body portion being formed, integrally with each other, of an aluminum alloy which contains not smaller than 5 wt. % of silicon, the hollow cylindrical head portion having a closure member which closes the open end of the hollow cylindrical body portion and which is formed of a material different from that of the engaging portion and the hollow cylindrical body portion.
The present arrangement permits easy manufacture of the piston having a lightweight, hollow head portion. The aluminum alloy containing not smaller than 5 wt. % of silicon exhibits an excellent wear resistance, so that the piston exhibits a required durability at its engaging portion. In other words, the engaging portion of the piston has excellent durability at part-spherical inner surfaces of recesses formed therein for slidably receiving the pair of shoes.
(3) A piston according to the above mode (2), the closure member is formed of a synthetic resin.
The closure member formed of a synthetic resin has a reduced weight, and can be economically manufactured by injection molding, for thereby reducing the weight and cost of manufacture of the piston. The synthetic resin preferably contains a glass fiber as a reinforcing material. The body portion formed of the aluminum alloy, and the closure member formed of the synthetic resin are fixed together by caulking the cylindrical body portion against the closure member, or by bonding the body portion and the closure member together. The body portion and the closure member can be firmly fixed together by employing these methods in combination.
(4) A piston according to the above mode (3), the hollow cylindrical body portion includes, on the side of the open end, an axial end portion which has an outside diameter smaller than that of the other portion of the body portion, the axial end portion being expanded radially outwardly by radial thermal expansion of the closure member formed of the synthetic resin at an operating temperature of the piston, so that the outside diamete
Kato Takayuki
Takamatsu Masato
Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
Leslie Michael
Look Edward K.
Woodcock & Washburn LLP
LandOfFree
Swash plate type compressor piston whose end section is... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Swash plate type compressor piston whose end section is..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Swash plate type compressor piston whose end section is... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2819881