DE8008440U1 - Covered hose - Google Patents

Description

PATENT LAWYERS Dipl.-Phys. JÜRGEN WEISSE. Dipl.-Chem. Dr. RUDOLF WOLGAST

BÖKENBUSCH 41 D 5620 VELBERT 11-LANGENBERG P.O. Box 110386 · Telephone; (02127) 4019 x telex; 8516895

Utility model registration

Automotive Products, Limited, Tachbrook Road, Leamington Spa, Warwickshire, CV31 3ER, United Kingdom

Covered hose

The innovation concerns a sheathed hose.

In particular, the innovation is aimed at fluid hoses in automobiles, which are generally located in an aggressive environment in which these hoses are subject to chemical attack by mineral salt solutions and from the liquid conveyed in each

and withstand high pressures over a wide temperature range, e.g. from - 40 ° C to + 130 ° C must be able to. Hoses of this type are predominantly, but not exclusively, used as lines for

hydraulic clutches used in automobiles, on

however, they are also suitable as fuel lines.

The known hoses for couplings in motor vehicles are made from polyamide 11 or from polyamide 12 by extrusion. polyamide

35

and polyamide 12 have been used because they a combination of desirable for the application Possess properties, viz

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(a) they are resistant to hydraulic fluids and fuel;

(b) they are flexible even at low temperatures, and

(c) they are chemically resistant to a large number of inorganic salts and their solutions, the more important of which are the chlorides of sodium, magnesium and calcium, as well Caustic soda, all of which are contained in street salt, even if only in traces.

A major disadvantage of tubing made of polyamide and polyamide 12 is that so, for example Tubing made of polyamide 12, which is flexible even at low temperatures, at temperatures around 100 ° below the hood of the motor vehicle so flexible that when hydraulic pressure builds up in the clutch master cylinder the internal pressure in the hose causes the polyamide 12 to expand outwards. This expansion leads in connection with the thermal expansion of the hose to the fact that the entire Liquid displacement from the main cylinder is absorbed within the hose made of polyamide 12 and is not transferred to the servo cylinder for the clutch. It can therefore be difficult and even impossible the clutch release mechanism

at temperatures of more than 70 ° C under the hood to operate.

One method of keeping this problem within manageable limits is to increase the wall thickness to enlarge the hose made of polyamide 12 so that the hose is sufficiently stiff at e.g. 100 ° C, to reduce the expansion to a minimum. This is the case for a line with a hole of 5 mm Diameter an increase in wall thickness to 2 mm, i.e. an outside diameter of 8 mm, is typical. However, are Polyamide 11 and polyamide 12 are very expensive materials and such an increase in wall thickness is therefore economically undesirable.

The task of the innovation is to design a hose of the aforementioned type so that it is under economically viable conditions is able to withstand all loads occurring in the company, in particular is mechanically resistant even at higher temperatures and remains flexible over the entire range of working temperatures.

According to the innovation, this object is achieved in that the inner tube is a polyamide, its flexural strength and hardness is not less than that of polyamide 6, and the sheath is made of a polyamide, whose chemical resistance to mineral salts is not lower than that of polyamide 11.

An exemplary embodiment of the innovation is shown in the figures and is explained below with reference to the Reference numerals explained and described in detail. Show it

Fig. 1 is a perspective view of a

sheathed hose according to the innovation, in which the sheathing over a part the length has been removed; and

Fig. 2 is a section along the line II-II in Fig. 1.

A hose 21 consists of a hose 22 formed from polyamide 6 or polyamide 66 by extrusion a sheath 23 made of polyamide 11 or polyamide 12, which was also molded onto the outer surface of the tube 22 by extrusion. As is well known, they are Polyamide plastics are designated as follows: 15

Polyamide 6: polycaprolactam;

Polyamide 66: condensation product of hexamethylenediamine

and adipic acid;

Polyamide 11: polyundecylene lactam; Polyamide 12: polylaurolactam.

The hose 22 made of polyamide 6 or polyamide 66 can have a bore of at least approximately 3 mm, but preferably 5 mm and a maximum outer diameter of approx. 10 mm, but preferably 8 mm. Such a Hose would have the necessary strength and strength under the hood at temperatures of 100 to 130 ° C Have stiffness, but only at half the cost

a tube of the same dimensions made of polyamide 11 or on
^ou polyamide 12. The necessary chemical resistance is then provided by the sheathing 23 made of polyamide 11 or polyamide 12, which has a protective effect.

The sheathed hose assembled in this way can withstand a minimum burst pressure of 200 bar at 23 ° C.

Claims (5)

ι ■ atf protection claims 1. Covered hose, characterized in that the inner tube (22) made of a polyamide whose flexural strength and hardness are not below the of polyamide 6, and the sheath (23) consists of a polyamide whose chemical Resistance to mineral salts is not lower than that of polyamide 11. 2. Sheathed hose according to claim 1, characterized in that the sheath (23) consists of Polyamide 12 is made. 3. Covered hose according to claim 1, characterized characterized in that the sheathing (23) consists of polyamide 11. 4. Covered hose according to one of the preceding Claims, characterized in that the hose (22) consists of polyamide 6. 5. Covered hose according to one of claims to 3, characterized in that the hose (22) consists of polyamide (66).