Pipes and tubular conduits – Distinct layers – Bonded to each other
Reexamination Certificate
2000-01-11
2001-12-11
Hook, James (Department: 3752)
Pipes and tubular conduits
Distinct layers
Bonded to each other
C138S127000, C138S146000
Reexamination Certificate
active
06328075
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a hose which can beneficially be used for transporting carbon dioxide as a refrigerant in an automobile air conditioner or the like. More particularly, it relates to a hose having an improved and reliable impermeability to carbon dioxide having a very low molecular weight as compared with flons such as Freons, even when it is subjected to high temperature and pressure.
2. Description of the Related Art
There has been a large demand for a hose having a wall not allowing the permeation of the refrigerant transported therein, and thereby overcoming various problems including the destruction of the ozone layer by Freons, or satisfying various requirements including a demand for a cooler system not calling for any replenishment of its refrigerant. The transportation of carbon dioxide as a refrigerant has, among others, been found to require an improved hose, since it has a low molecular weight and easily permeates through the wall of the hose, particularly when the hose is subjected to high temperature and pressure.
Accordingly, there has been proposed a hose having a wall composed of a plurality of layers including a rubber layer and an impermeable(or low-permeable) layer formed from a resin having a relatively high impermeability to a refrigerant, such as EVOH or nylon, or a like layer formed of a metallic foil having a high impermeability to a refrigerant. An impermeable layer formed from a resin, however, requires a considerably large thickness for the wall of a hose to resist the permeation of carbon dioxide transported as a refrigerant for a compressor in an automobile or the like. The hose is, therefore, likely to lack flexibility and have its wall cracked, or have its impermeable layer separated from a rubber layer adjoining it, due to a bending stress produced by the vibration of the compressor or the automobile.
A layer formed of a metallic foil, particularly a laminate of foils united by a fused resin film to increase the strength, is useful for making a hose having a wall of high impermeability to carbon dioxide without depriving it of flexibility. The pressure to which the hose is subjected is, however, so high that the expansion or elongation of the hose may cause the stretching of its wall resulting in the breakage of the foil. Thus, the impermeability of the wall will be seriously lowered at the critical point of breakage of the layer.
SUMMARY OF THE INVENTION
It is, therefore, an object of this invention to provide a hose which can beneficially be used to transport carbon dioxide refrigerant, since its wall has a satisfactorily high level of impermeability to carbon dioxide while retaining its flexibility, thus obviating the critical point of breakage causing remarkable decrease in impermeability due to the expansion or elongation of the hose.
This object is essentially attained by a hose having a wall formed by a plurality of layers including at least one impermeable metallic layer formed by vapor deposition, thereby obviating the critical point in carbon dioxide permeation property due to change in radius and length of the impermeable layer. The metallic layer formed by vapor deposition is very unlikely to deprive the hose of its flexibility, and thus retains a wall having a satisfactorily high level of impermeability to carbon dioxide.
A layer formed by a metallic foil is nearly completely impermeable to carbon dioxide, but its impermeability is greatly lowered upon breakage of the foil under tension. On the other hand, a layer formed by vapor deposition is more reliable, though its original impermeability to carbon dioxide may be somewhat lower than that of a foil. It does not break easily under tension, but remains substantially unchanged in impermeability even under tension. Thus, it is more advantageous to use a layer formed by vapor deposition so far as a particular level of impermeability to carbon dioxide can be obtained by using it, or by combining it with other means enabling it to exhibit a still higher level of impermeability. As it does not break easily, it is also free from any such concentration of stress as occurs at a broken part of a foil which in turn causes another layer, as of a resin, to break.
The above and other objects and advantages of this invention will become more apparent from the following description and the accompanying drawings.
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patent: 5476121 (1995-12-01), Yoshikawa et al.
patent: 5488975 (1996-02-01), Chiles et al.
patent: 5688556 (1997-11-01), Wagner, Jr.
patent: 5718956 (1998-02-01), Gladfelter et al.
patent: 6074717 (2000-06-01), Little et al.
patent: 04131233 (1992-05-01), None
patent: 11264488 (1999-09-01), None
Furuta Norihiko
Ikemoto Ayumu
Niki Nobuaki
Hook James
Jacobson & Holman PLLC
Tokai Rubber Industries Ltd.
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