Pipes and tubular conduits – Distinct layers – With intermediate insulation layer
Reexamination Certificate
1999-09-16
2001-01-30
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Distinct layers
With intermediate insulation layer
C138S132000, C138S129000, C138S137000, C138S144000
Reexamination Certificate
active
06179009
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a gas transfer duct, and particularly to a gas transfer duct having a heat-insulating effect and a noise reducing effect suitable for transferring air-conditioning air which is set to have temperature different from room temperature.
A conventional transfer ducts of such a type generally have a structure in which heat-insulating foamed material is spirally wound around an outer circumferential portion of a duct body with no space, and the duct body forms an inner circumferential surface of the duct.
In such a manner, in a conventional duct having a structure in which a duct body forms an inner circumferential surface of the duct, the duct becomes a guide cylinder through which noise generated from an air-blow source such as an air blower is guided to an opening portion of the duct while gas is transferred. The noise is discharged together with the gas so as to give people an unpleasant feeling. There has been a problem that such noise jars on people's nerves because it is generated continuously while the duct is in use, that is, in air-blowing operation.
In order to largely reduce such an unpleasant noise discharged from an opening of a duct to solve the above-mentioned problem belonging to air-blow ducts of a conventional type though it may be impossible to entirely extinguish such an unpleasant noise, there has been developed and proposed one means (see Japanese patent unexamined publication No. Hei. 9-89357) which has such a structure as follows. That is, woven cloth of predetermined width is wound spirally, and then, the connection edges of the cloth are bonded to each other with hard resin strip material, so that an internal surface layer of a duct is formed. A foam strip of open cells is spirally wound on the outer circumferential surface of the woven cloth while adjacent side edges of the foam strip are brought into contact with each other, so that an open-cell foam is formed. A thin film sheet-like strip is spirally wound on the outer circumferential surface of the open-cell foam so as to form an intermediate sheet layer. A foam strip of closed cells is spirally wound on the outer circumferential surface of the intermediate sheet layer so as to form a closed-cell foam. A resin tape is spirally wound on the outermost circumference of the closed-cell foam so as to form an external surface layer which wraps the outermost circumference.
This air-blow duct is a product having a superior effect to be able to show substantially practically perfect effects of noise reducing and heat insulating functions as expected. The duct is therefore an ideal and suitable product for use as an air-blow duct. This product has, however, only one problem that the manufacturing process is complicated and expensive.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a sound-absorbing and heat-insulating duct which is simple, not complicated, in structure if the constituent materials are selected, which can achieve both sound-absorbing and heat-insulating functions in spite of its simple structure, which is suitable for use as an air-blow duct, and which is suitable for continuous production so that the duct can be mass-produced inexpensively without requiring any new equipment.
The above object can be attained by a heat-insulating and noise reducing duct, according to the present invention, comprising a reinforcing core, a thick felt layer, a form strip layer and a resin-coating layer. The reinforcing core is made of hard polyolefin resin material and wound spirally at predetermined intervals. The thick felt layer is wound spirally so that adjacent side edge portions of the felt layer are lapped over or brought into contact with each other, while the shape of the felt layer is retained by the reinforcing core. The foam strip layer is made of polyolefin resin material and wound spirally on an outer circumferential surface of the felt layer so that adjacent side edge portions of the foam strip layer are in abutment against or in tight contact with each other. The resin-coating layer provided to cover an outer circumferential surface of the foam strip layer.
In order to carrying out the present invention, it is preferable that the reinforcing core is constituted by a wire having a semicircular shape in section, and a linear surface of the reinforcing core is disposed to face the inner surface of the duct.
Further, in the above-mentioned construction, it is advantageous that the resin-coating layer is formed by winding a tape made of polyolefin resin or polyvinyl chloride resin spirally.
Furthermore, in the above-mentioned construction, it is also advantageous that a the felt material constituting the felt layer is formed of needle felt made of polyolefin resin.
Moreover, in the above-mentioned construction, it is also advantageous that the back surface of the felt material is smoothed by fluffing treatment by flame and the felt material is provided so that the smooth-treated surface of the felt material is positioned on the inner surface side of the duct.
REFERENCES:
patent: 3548884 (1970-12-01), Ambrose
patent: 3916953 (1975-11-01), Nagayoshi et al.
patent: 4620569 (1986-11-01), Von Glanstatten et al.
patent: 5795634 (1998-08-01), Fukui
patent: 5806567 (1998-09-01), Fukui et al.
patent: 9-89357 (1997-04-01), None
Brinson Patrick
McGinn & Gibb PLLC
Totaku Industries, Inc.
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