Device forming a leak-proof connection between a rigid tube end

Details Device forming a leak-proof connection between a rigid tube end Device forming a leak-proof connection between a rigid tube end

1998-01-15

1999-10-05

Arola, Dave W.

Pipe joints or couplings

Nonmetal to metal

Internal member

285903, 29516, 29890144, F16L 33207

Patent

active

059611570

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a device forming a leaktight connection between a rigid tube end-piece and the end of a supple, flexible pipe by crimping a part in the form of a metal sleeve onto the end of the pipe.
It also relates to a method for making such a leaktight connection device.
It finds a particularly important although not exclusive application in the field of connections in cooling circuits, air-conditioning circuits and/or power-assisted steering systems in motor vehicles.
Devices for the leaktight connection between a rigid tube end-piece and a flexible elastomer pipe, for example made of rubber, are already known.
The rigid tube end-piece is generally force-fitted directly onto the flexible pipe around which a metal sleeve is crimped.
An assembly of this kind does, however, require a number of different operations, including an operation of longitudinally pushing the flexible pipe onto the previously machined end-piece, and a radial crimping operation.
To simplify these operations, U.S. Pat. No. 5,417,461 proposes that the end of the pipe be fitted directly in abutment in the end-piece, an insert equipped with an end collar with a seal having previously been assembled on the pipe, the collar and the pipe being crimped simultaneously into the end-piece in a single operation.
Although the assembly of a device of this kind is thus made easier, this is achieved at the cost of the ability to withstand vibration.
Devices including end-pieces with welded inserts are also known (U.S. Pat. Nos. 3,479,713; 5,370,425), and although these give a better seal and have improved resistance to vibration, they are complicated to use, especially because of the welding.
In general, the known devices have drawbacks.
They do not always guarantee a good seal especially when used with certain refrigerants, for example such as the liquid known by the reference 134a+PAG oil.
Furthermore, motor manufacturers are constantly raising their requirements regarding the resistance to wear and to the arduous environmental conditions of the connection devices used in their vehicles.
Thus, the systems known to date in particular are unable to maintain a good enough seal during endurance testing which may include more than 150,000 operating cycles at temperatures which can range between -35.degree. C. and +150.degree. C.
The present invention aims to provide a connection device, and a method of making a connection device which meet the practical requirements better than those known before, especially in that the invention allows simple, quick and repetitive manufacture with great flexibility for adaptation, and in that it guarantees optimum crushing of the pipe made of flexible material without it being damaged, and does so while at the same time allowing the desired result, namely better leaktightness of the connection device, to be obtained, all this being achieved with excellent ability to withstand vibration, for an optimized cost.
To this end, the present invention provides, in particular, a device forming a leaktight connection between a rigid tube end-piece and the end of a flexible pipe, by crimping a part in the form of a metal sleeve onto the said end, the rigid tube end-piece comprising a terminal part comprising a shoulder of larger diameter than the tube, the said device including a rigid insert hollowed out from end to end by a bore, the said insert comprising, on the one side, a tubular part forcibly inserted into the end of the pipe facing the crimped portion of the part in the form of a metal sleeve, and, on the other side, a part equipped with an external collar of complementary shape, and in abutment with the shoulder, the said collar being extended, on the other side from the said tubular part with respect to the collar, by a tubular end-piece, characterized in that the bore in the insert is cylindrical and in that the end-piece is forcibly inserted over a determined length into a non-deformed part of the end-piece of the rigid tube and comprises seal-type sealing means.
Advantageously, the determined len

REFERENCES:
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patent: 2319586 (1943-05-01), Clench
patent: 2401921 (1946-06-01), Fisher et al.
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patent: 3690703 (1972-09-01), Phillipps
patent: 5096231 (1992-03-01), Chisnell et al.
patent: 5417461 (1995-05-01), Dougherty et al.

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