Air conditioning hose

Details Air conditioning hose Air conditioning hose

1998-03-26

2002-04-23

Pyon, Harold (Department: 1772)

Stock material or miscellaneous articles

Hollow or container type article

Polymer or resin containing

C138S125000, C428S036900, C428S474400, C428S474900, C428S476900

Reexamination Certificate

active

06376036

ABSTRACT:

TECHNICAL FIELD
The disclosed invention is directed toward an air conditioning hose. Specifically, the disclosed invention is an automotive air conditioning hose capable of withstanding high temperature fluid flow of up to at least 150° C. therein.
BACKGROUND OF THE INVENTION
Hoses have been developed which are useful for automobile air conditioners, wherein hoses or other suitable flexible conduit members are employed for the purpose of joining the principal operating components of the refrigerating device. These hoses should have good flexibility, high strength, the ability to bend to small radii without kinking, small outside diameter in relation to inside diameter and impermeability to the fluids involved. In addition, these refrigeration hoses are subjected to temperature extremes in under-the-hood applications, and further, must meet requirements for proper coupling attachment.
Prior art automotive air conditioner hoses employ a three-layer structure. The innermost tubular layer of the hose is typically formed of an elastomeric material intended to keep the refrigerant fluid and compressor lubricant in the hose and moisture and air out. A layer of reinforcing braiding is wound upon the outside surface of the inner tube. An outer layer of elastomer resistant to ozone, engine oil and other contaminating materials likely to be present in the engine compartment is typically extruded over the braided reinforcement. In hoses of this type, the inner layer is acrylonitrile-butadiene rubber or chlorosulfonated polyethylene, the braiding fibers may be rayon and other conventional fibers, and the outer layer is neoprene or EPDM.
Even though numerous refrigerant hose designs have been developed, they fail to combine low Freon permeability, low water permeability, high flexibility, vibration resistance and good coupling properties to the hose over temperature extremes.
Conventional hoses, due to the thickness and a corresponding lack of flexibility, provide little noise damping. The noise generated can be detected within the passenger cabin of the automobile. It is desired by the automotive industry to reduce cabin noise as much as possible to provide a quiet ride. The more flexible the hose is, the greater is the noise damping effect of the hose. The present invention is directed toward a hose with greater flexibility and thus greater noise dampening.
The normal operating temperatures encountered by air conditioning hose assemblies employed in automotive air conditioning generally ranges from about −30° to about 120° C. Design specifications require that such hose assemblies operate equally well at temperature ranges of about −40° to 150° C. The higher temperatures are due mainly to the location of the system proximate the engine as well as from the heat generated in compressing the refrigerant as a gas.
U.S. Pat. No. 4,633,912 discloses a composite hose for Freon gas, comprising a polyamide core tube, an elastic friction layer having the specific composition and being directly provided on a core tube, a first reinforcement strand layer, an adhesive barrier friction layer, a second reinforcement strand layer, and then a cover layer. The elastic friction layer provided directly on the core tube comprises (a) a base rubber selected from EPDM, a copolymer of butadiene, polychloroprene, polybutadiene, polyisoprene or a mixture thereof, (b) a calcium ion source, (c) resorcinol or a phenol-based adhesive system, and (d) a peroxide or a sulfuric vulcanizing agent. The calcium source (b) is said to make better adhesion to a polyamide of the core tube. The adhesive barrier friction layer being present between the first and second reinforcement strand layers is provided to minimize a friction of the strands, and is made of a copolymer of ethylene and acrylic acid. For the cover layer, a halogenated butyl rubber containing bis-dienophile as a crosslinking agent is used.
U.S. Pat. No. 5,488,974 discloses a composite hose for automotive air conditioning systems. The hose consists of the innermost layer, the intermediate rubber layer, a fibrous reinforcement layer and an external rubber layer, each of which is formed in this order from the inside. The innermost layer is formed of a modified polyamide obtainable by blending of a polyamide and a carboxyl-containing modified polyolefin, and the intermediate rubber layer is formed of a rubber composition obtainable by a blend of 10 to 50 parts by weight of silicic acid or a salt thereof and 5 to 15 parts by weight of a brominated alkylphenol formaldehyde resin per 100 parts of the rubber material obtainable by blending butyl rubber and a halogenated butyl rubber at a weight ratio of 50/50 to 0/100.
SUMMARY OF THE INVENTION
The disclosed invention is a hose, preferably for use in automotive air conditioning units. The four layer hose exhibits high flexibility, high gas impermeability, and a resistance to high temperatures within the range of 150° C.
The present invention discloses a hose comprising an innermost core layer comprised of non-plasticized polyamide; an intermediate reinforcing layer comprised of aramid fibers, and an outermost layer of acrylic rubber compound.
A further aspect of the disclosed invention includes a friction coat rubber layer disposed between the innermost core layer and the intermediate reinforcing layer, the friction coat layer comprised of ethylene propylene diene rubber and 75 parts by weight of carbon black.
A further aspect of the disclosed hose is the friction coat rubber is a 50/50 weight percent blend of two ethylene propylene diene rubbers, the two rubbers having differing Mooney viscosities.
The disclosed invention further discloses an automotive air conditioning hose with an innermost layer, a friction coating layer, an intermediate reinforcing layer, and an outermost layer, wherein 1) the innermost layer is comprised of non-plasticized nylon-6 blended with an EPDM rubber at a weight ratio of 95/5 to 85/15; 2)the friction coat layer is comprised of a 50/50 weight percent blend of two EPDM rubber with differing Mooney viscosities, and 75 parts by weight of carbon black; 3) the intermediate reinforcing layer is comprised of adhesively treated aramid fibers; and 4)the outermost layer is comprised of a 50/50 weight percent blend of two ethylene acrylates with differing Mooney viscosities, and 80 parts by weight of carbon black.
DETAILED DESCRIPTION OF THE INVENTION
The hose of the present invention is comprised of a core tube. The core tube is formed from a selected resin, with high impermeability against the fluid which flows therein. The core tube is provided with an outer friction layer, selected for its adhesion ability to the core tube and the adjacent reinforcement layer. The reinforcement layer is comprised of a strand which provides a high flex dynamic performance. The outermost layer of the tube is a thermoplastic rubber layer.
The core layer of the hose is a resin polyamide. Polyamide resin is preferred as providing a good balance between impermeability and flexibility. To provide adhesion to the friction coat layer, the polyamide resin may be formed of a blend material consisting of polyamide resin and a polyolefin rubber material. For the improved adhesion to the friction coat layer, the polyolefin selected should be selected from among the main rubber constituents of the friction coat layer. The weight ratio of polyamide to polyolefin ranges from 95/05 to 85/15. Nylon-6 is preferable as the selected polyamide resin, with a 6% blend of ethylene propylene diene rubber, corresponding to the preferred composition of the friction coat layer. Other conventional nylons, such as nylon 66, nylon 11, were determined to not be able to provide the required adhesion in combination with the needed flexibility and impermeability as the nylon 6.
Additionally, the polyamide resin is non-plasticized. The core may be formed by conventional methods, such as extrusion. While conventionally, a non-plasticization of the resin would result in a tube of higher bending strength and lower flexibility, the effects are

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