SK4692001A3 - Fabric sleeve for a rubber tube - Google Patents

Abstract

A protective fabric sleeve (1) for a rubber tube comprises heat-recoverable interlaced strands forming an elastically deformable tubular structure, the strands comprising at least one monofilament yarn (2) and at least one multifilament yarn (3). Use especially for a coupling in a fluid circuits of a motor vehicle.

Description

The invention relates to a sheath of fabric for a rubber hose, in particular for a rubber connecting hose used in a fluid circuit for an engine of a motor vehicle. It further relates to a method of manufacturing such a rubber hose surrounded by a sheath according to the invention.

BACKGROUND OF THE INVENTION

It is known to reinforce rubber hoses for use in fluid circuits with a mechanical reinforcement of fabric embedded in the thickness of the hose. This textile reinforcement makes it possible to increase the resistance of the hoses to the internal pressure exerted by the fluid. Conventional methods for manufacturing such reinforced hoses are mainly by extruding a rubber tubular substrate onto which the fiber fabric is wound, woven or knitted, after which a new rubber layer for embedding the fibrous textile reinforcement is extruded. One such method as described in US-A-3755032 consists in wrapping such a fabric in situ on a rubber tubing substrate of heat-shrinkable polymer filaments and using the vulcanization temperature to which the rubber is subjected to shrink the fiber reinforcement layer into a predetermined position in the hose.

It is further known to use a mechanical protective sheath disposed around a rubber hose, which allows to protect the rubber hose against external stress and improve its abrasion resistance. Such an outer sheath is described, for example, in U.S. Pat. No. 5,366,771. It comprises a fabric in which heat-shrinkable yarns and heat-stable yarns are mixed, the fabric itself being embedded in a polymer film. The fabric is made in a mold

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It is wrapped around the hose, and the longitudinal edges are then fastened together to form a sheath around the hose.

It is also known from European patent EP-A-024933 to produce a sheath for mechanical protection intended to surround a substrate as a bundle of wires, interweaving monofilament yarns having a degree of elasticity allowing relative relative movement so that the sheath can expand radially for insertion on the substrate by exerting an axially pulling force, allowing the casing to resiliently return to its original length and diameter. Since the sheath requires axial contraction, the monofilaments are selected for their resilient properties, the braid may be open to allow contraction, which is usually not consistent with the best protection of the substrate.

US-A-5 197 370 similarly discloses a tubular sheath of interwoven monofilaments for axial contraction, but also includes axially arranged warp threads from a flabby, inelastic multifilament yarn that allows the casing to axially contract to allow radial expansion for placement around the substrate. , without collision with retraction and subsequent return to service length. While such multifilament warp yarns can provide additional physical protection and tensile properties by preventing the sheath in the longitudinal direction from extending beyond the produced length, there are problems with the sheath having to contract around its substrate and the difficulty in tracking direction changes. such substrates which cause different expansions on opposite sides of the sheath.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheath of fabric which, in particular, allows it to be mounted on a rubber hose and facilitates the manufacture of the hose.

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SUMMARY OF THE INVENTION

The invention provides a sheath of fabric for a rubber hose, characterized in that it comprises heat-shrinkable interwoven strands forming a resiliently deformable tubular structure, wherein the strands are present in the form of at least one monofilament yarn and at least one multifilament yarn.

Although the sheath is tubular, its resilient structure makes it easier to fit on the rubber hose, and allows it to deform while slipping onto the hose.

In addition, the thermal shrinkage of the strands permits the formation of a sheath having a diameter greater than the outer diameter of the hose before shrinking, so that it is simply slid onto the hose.

The tubular sheath according to the invention is therefore perfectly suited for sliding on a rubber hose of various shapes, and in particular a hose having many bends.

Due to the tubular shape of the protective sheath and the use of at least two types of different threads, one of which is a monofilament yarn and the other is a multifilament yarn, an outer sheath is obtained allowing both mechanical protection against abrasion of the rubber hose and reinforcing the hose against internal pressure exerted by liquids. .

The monofilament yarn allows the sheath to be flexibly held against the rubber hose and exerts a force sufficient to reinforce the hose against internal pressure. In addition, the monofilament yarn holds the multifilament yarn so that it abuts the rubber hose, thereby increasing the ability of the multifilament yarn to protect the rubber hose against external loads and against the risk of wear.

In addition to the advantages of fitting the sheath and reinforcing the rubber hoses, the fabric sheath according to the invention also makes it possible to refrain from inserting the textile reinforcement into the rubber mass constituting the hose. Hose production is a team

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According to a preferred embodiment of the invention, the heat shrinkage coefficients of the monofilament yarn and the multifilament yarn are approximately the same.

Thermal shrinkage of the textile sheath around the hose occurs evenly over all strands, so that wrinkles on the sheath surface are eliminated, which would reduce its abrasion resistance and facilitate its damage.

Shrinkage coefficients of less than 40% are preferred, i. the difference in the length of the yarn before and after heat shrinkage remains less than 40% of its initial length. The Applicant has found that above this threshold, and unless the diameter of the fabric sheath is greatly increased, thermal shrinkage of the sheath may cause deformation of the rubber hose and may in particular change its path and limit its inner diameter.

Since the shrinkage coefficients of the monofilament yarn and the multifilament yarn are not exactly the same, according to a preferred embodiment of the invention, the shrinkage coefficient of the monofilament yarn is slightly greater than the shrinkage coefficient of the multifilament yarn.

This measure also prevents the formation of wrinkles on the surface of the fabric sheath after shrinking. This is because the multifilament yarn, which is more squeezable than the monofilament yarn, can absorb a slight additional recovery of the sheath caused by the monofilament yarn beyond its inherent shrinkage when compressed.

According to a preferred embodiment, by which the fabric sheath is provided with great flexibility and flexibility to facilitate its fitting, the strands are interconnected in the form of a braid braid whose diameter increases with longitudinal compression of the braid.

Preferably, the monofilament yarn is made of polyethylene glycol terephthalate (according to the nomenclature of CSN 64 0001, polyethylene terephthalate according to the international nomenclature, PET) having a high elasticity, and

31689 / T ····················· Multifilament yarn is made of high tenacity polyamide. This fabric sheath composition is well suited for its dual function of reinforcing the hose against its internal pressure and for its mechanical protection.

According to a further feature of the invention, the method of manufacturing a rubber hose protected by a sheath of a fabric according to the invention is characterized in that the rubber hose is extruded, the hose is shaped, a sheath of a fabric slightly larger than the diameter of the rubber hose is fitted and The cladding of the fabric is vulcanized, causing thermal shrinkage of the fabric.

This manufacturing process makes it possible to produce a rubber hose by continuous extrusion, as opposed to conventional manufacturing processes that require successive extrusion processes to incorporate the textile reinforcement into the rubber hose. Further, the sheath undergoes shrinkage during vulcanization at elevated temperature and thus does not require an additional process as compared to conventional rubber hose manufacturing processes.

The invention further provides a rubber hose, in particular for forming a connection section in the fluid circuit of the engine, characterized in that it is constituted by a rubber hose covered by a textile jacket according to the invention. Thus, the rubber hose is reinforced on the outside by a sheath of fabric that perfectly matches its shape and does not create any increased thickness or folds on its surface.

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Swap the figures in the drawings

BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in more detail below with reference to the accompanying drawings, in which: FIG. 1 shows a detail of a fabric sheath according to the invention, FIG. 2 is a perspective view of a rubber hose according to the invention; and FIG. 3A-3E are schematic diagrams of the various stages of the manufacturing process of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will first be described with reference to FIG. The fabric sheath 1 is suitable for covering and protecting rubber hoses, such as connecting hoses used in fluid circuits in motor vehicles.

The fabric sheath 1 is formed from interconnected, heat-shrinkable strands 2, 3, i. strands exhibiting heat shrinkage. This shrinkage of each strand can be measured using a shrinkage coefficient corresponding to the maximum difference in length of the strand before and after shrinkage with respect to its initial length before the heat shrinkage. Throughout the rest of the description, the shrinkage coefficient corresponds to the shrinkage measured in a dry oven at 200 ° C.

The interconnected strands 2, 3 form a resiliently deformable tubular structure. In this example, the strands 2, 3 are interconnected in the form of a braid bead whose diameter increases as the bead is compressed longitudinally. Of course, any other fabric construction that is elastically deformable in the diameter direction and in the longitudinal direction may be suitable. In particular, the sheath fabric can be formed from interlocking strands 2, 3 in the form of a knitted fabric whose diameter increases with longitudinal compression of the fabric.

As is clearly seen in FIG. 1, the strands consist of monofilament yarns 2 and multifilament yarns 3. The terms monofilament strand "and multifilament strand" are used throughout the text to distinguish those of the strands,

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These are made up of monofilament yarns and those strands. which consist of multifilament yarns. The shrinkage coefficients of the monofilament yarn 2 and multifilament yarn 3 are approximately the same and remain less than 40%.

By keeping the shrinkage coefficient at a significant but not too high value, deformation of the hose is prevented during the recovery of the sheath from the fabric, while at the same time allowing pulling of the molding tool inserted into the hose, such as a mandrel, is not prevented.

Since the shrinkage coefficients of the monofilament yarn 2 and the multifilament yarn 3 are not identical, it is preferred that the shrinkage coefficient of the monofilament yarn 2 is slightly greater than the shrinkage coefficient of the multifilament yarn, which is less susceptible to crease formation because it is easily compressible.

Thus, the shrinkage coefficient of monofilament yarn 2 is from one to three times the shrinkage coefficient of multifilament yarn 3, and preferably from 1.5 to 2 times the shrinkage coefficient of multifilament yarn 3. Generally speaking, the shrinkage coefficient of monofilament yarn 2 is from half to four times the shrinkage coefficient.

The shrinkage coefficient of monofilament yarn 2 is from 3% to 40%, and the shrinkage coefficient of multifilament yarn 3 is from 1% to 20%. In particular, the shrinkage coefficient of monofilament yarn 2 is from 5% to 30%, and the shrinkage coefficient of multifilament yarn 3 is from 5% to 15%. In this example, the shrinkage coefficient of monofilament yarn 2 is from 15% to 25%, and the shrinkage coefficient of multifilament yarn 3 is from 8% to 15%.

The proportions of monofilament yarns and multifilament yarns in the fabric sheath may vary over a wide range as long as the sheath flexibility remains sufficient to allow it to be easily threaded. As a rule, the interlocking strands in the fabric are spaced such that two monofilament threads 2 per multifilament thread 3 and one monofilament thread 2 per ten multifilament threads 3, and preferably from one monofilament thread 2 per multifilament thread 3 to one monofilament thread 2 per four

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The multifilament yarns 3. In the present example, the proportion is preferably one monofilament yarn 2 per three multifilament yarns. threads 3. One monofilament thread 2 may also be used for two multifilament threads 3.

Typically, a monofilament yarn with a very high modulus of elasticity will be present in a lower proportion than the monofilament yarn with a lower modulus, based on the total weight of the multifilament yarns used. The monofilament yarn 2 used for its elasticity will generally be made of polyethylene glycol terephthalate (PET). It may consist of any polymer having a high modulus of elasticity, such as olefin polymers, polyesters, polyphenylene oxides and sulfides, silicone carbonate block copolymers, polyketones, polysulfines, polycarbonates, polyamides, epoxy resins, and mixtures of these materials.

The multi-filament yarn 3 used for its abrasion resistance will preferably consist of a polyamide such as nylon-6 or nylon-6,6. Other types of polyamide or abrasion resistant polymer may be selected.

The fabric sheath 1 is placed on the hose by the manufacturing process shown in FIG. 3A to 3E. As shown in FIG. 3A, the rubber hose 4 is extruded by a conventional extrusion process. In contrast to the prior art, in which the fiber reinforcement is inserted into the mass of the hose 4, the hose according to the invention can be continuously extruded from the fabric due to the subsequent use of the sheath. Further downstream of the extruder 5 is a cutting device 6 which allows the rubber hose to be cut to the desired length.

In the molding step shown in FIG. 3B, the rubber hose is preferably pushed onto the tubular mandrel 7. FIG. 3C shows the suction of the fabric sheath 1 onto the hose, the diameter of the fabric sheath 7 being slightly larger than the diameter of the hose 4. The fitting is further facilitated by the elastic deformation of the sheath and the fabric, as explained above, so as to enlarge it. diameter by pressing in the longitudinal direction.

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In the next step, the rubber hose 4, mounted on the mandrel 7 and covered by the jacket 1 of the fabric, is vulcanized as shown in FIG. 3D, preferably in an autoclave furnace 8. The vulcanization causes a thermal shrinkage of the fabric sheath 1, which thus perfectly matches the outer surface of the rubber hose 4. In this embodiment, the vulcanization is preferably carried out at a temperature of about 180 ° C. Of course, the vulcanization temperature depends on the type of rubber used to make the hose 4.

After vulcanization, the mandrel 7 is pulled out as shown in FIG. 3E. As explained above, the shrinkage coefficients of the strands from which the sheath fabric 1 is formed are not too high so that the heat shrinkage force exerted by the sheath even from the fabric prevents the drawing of darkness.

The rubber hose shown in FIG. 2, consisting of a rubber hose 4 covered by a sheath 1 of a fabric. The properties of the protective sheath 1 make it possible to adapt it to the surface of the hose 4 without forming creases or areas of increased thickness, especially in the creases of the hose.

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PATENT CLAIMS

Claims (16)

A fabric sheath suitable for surrounding a rubber hose and providing a protective surface thereof, comprising a resiliently deformable tubular structure of at least one resiliently deformable monofilament yarn having a heat shrinkage capability, characterized in that said monofilament yarn has a heat shrinkage coefficient ranging from 3 to 40%, wherein at least one deformable multifilament yarn, abrasion-resistant and heat-shrinkable, having a heat-shrinkage coefficient of not more than said monofilament yarn, is bound thereto in a circumferentially complete and longitudinal direction of the flexible tubular structure. thread shrinkage for clamping the cross section of the tubular sheath as a function of thermal shrinkage of the monofilament yarn. The fabric sheath of claim 1, wherein said multifilament yarn has a heat shrinkage coefficient substantially the same as the monofilament yarn. The fabric sheath of claim 1, wherein said multifilament yarn has a heat shrinkage coefficient of less than the monofilament yarn, wherein the sheath is sensitive to thermal shrinkage of the yarns to exert a radial compression force by the monofilament yarn to the multifilament yarn at the points where the monofilament yarn crosses multifilament yarn. Fabric sheath according to claim 3, characterized in that the shrinkage coefficient of the monofilament yarn is from one to three times the shrinkage coefficient of the multifilament yarn, preferably from one and a half times to two times the shrinkage coefficient of the multifilament yarn. 31689 / T ······························· ·· ·· ·· ·· · The fabric sheath of claim 3 or 4, wherein the sheath is sensitive to thermal shrinkage of the monofilament yarn to induce, in an operating condition surrounding the hose, contracting the sheath to the hose surface, and squeezing the multifilament yarn between the monofilament yarn and the hose surface. The fabric sheath of any one of claims 1 to 5, wherein said monofilament yarn has a shrinkage coefficient of from 1% to 20%. Fabric sheath according to claim 6, according to claim 3, characterized in that the shrinkage coefficient of the multifilament yarn (3) is from 8% to 15% and the shrinkage coefficient of the monofilament yarn (2) is from 15% to 25%. Fabric sheath according to any one of claims 1 to 7, characterized in that, in the fabric of interlocking strands (2, 3), two monofilament yarns (2) per multifilament yarn (3) fall into one monofilament yarn (2). ) for ten multifilament yarns (3). Fabric sheath according to claim 8, characterized in that in the fabric of the interwoven strands (2, 3), preferably one monofilament yarn (2) falls on two multifilament yarns (3) or one monofilament yarn (2) on three multifilament yarns threads (3). A textile sheath according to any one of claims 1 to 9, characterized in that the strands (2, 3) are interconnected in the form of a flexible tubular hollow flange whose diameter increases with longitudinal compression of the flange. A textile sheath according to any one of claims 1 to 9, characterized in that the strands (2, 3) are interconnected in the form of a resilient tubular article whose diameter increases with longitudinal compression of the tubular article. 31689 / T ······················ · · The sheath of fabric according to any one of claims 1 to 11, characterized in that the monofilament yarn (2) is made of polyethylene glycol terephthalate. The textile sheath according to any one of claims 1 to 12, characterized in that the mulfilament yarn (3) is made of polyamide. 14. A method of manufacturing a rubber hose by extruding a rubber hose, inserting a tubular mandrel into the extruded hose, enclosing the extruded hose with a shrinkable yarn shroud, vulcanizing the hose at an elevated temperature, causing the shrinkage of the surrounding yarn at said elevated temperature. and the mandrel is withdrawn from the vulcanized hose, characterized in that the extruded rubber hose is formed by deformation of the longitudinal axis, the heat-shrinkable yarn is arranged in a sheath of a fabric according to any one of claims 1 to 13 having a cross-section greater than that of the hose; of the fabric is slid along the shaped hose so that it surrounds it, before exposing the hose and its surrounding sheath to said vulcanization temperature. The production method according to claim 14, characterized in that the vulcanization of the hose with the jacket is carried out at a temperature of approximately 180 ° C. A rubber hose suitable for forming a hose coupling in a fluid circuit of an engine, having an outer hose surface formed by a fabric sheath according to any one of claims 1 to 13, wherein the fabric sheath is a rubber hose, wherein the rubber hose is in a vulcanized state and the fabric is in a heat-shrink condition and abuts the surface of the hose. 31689 / T • t • t ft γ .3B .3.3