The invention relates to a quick coupling device of the kind stated in the preamble of claim 1.

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Such a device is previously known and is used for temporary 5 connection of a pressurized fluid conduit, such as a hose, to a pipe nipple or the like, e.g. belonging to an armature, a pressure vessel or the like. The device is especially useful for such coupling in connection with tightness testing or leak detection, wherein a pressurized fluid, e.g. water or air 10 is to be fed to the armature in question, the pressure vessel or the like during a prescribed, usually rather short time per so that a large number of objects can be tested per time unit.

However, a drawback involved in the known devices is that an 15 effective sealing between the pipe nipple and the coupling device requires that the actuating force on a piston exceeds the compressive force exerted by the pressurized fluid used in the tightness test. In order to secure the required sealing effect, it may then be necessary to provide the piston with a 20 relatively large piston surface, so that a sufficiently great force is obtained. However, this implies rather large radial sions of the device.

Thus, the object of the present invention is to achieve a quic 25 coupling device which, in spite of compact radial dimensions, will secure an effective sealing, even when exposed to compara¬ tively high pressures of the pressurized fluid, whereas the actuating pressure can be maintained at a moderate or low level

_j 30 This object is achieved for an inventive coupling device, the features of which are principally stated in the characterizing part of claim 1. Thus, the device is provided with two mutually displacable pistons, one of which is actuated by an actuating fluid (e.g. pressurized air), whereas the other piston, i.e. 35 the coupling piston, is brought into sealing contact by the action of the actuating piston. The force exerted by the

pressurized fluid (e.g. water at high pressure) on the couplin piston is totally or partly eliminated in that the pressurized fluid acts on a piston surface turned away from the sealing.

c By msans of the inventive device the radial dimensions can be kept at a moderate level, and the pressure of the actuating fluid can be relatively low, whereas the pressure of the testi pressurized fluid can be rather high, while maintaining the sealing effect.- Further features and advantages will appear _ _Q from the description below and the claims 2-6.

The invention is explained in detail below with reference to t accompanying drawing, which illustrates a central section of a _5 quick coupling device connected to a pipe nipple having an ex¬ ternal flange.

Thus, to the left on the drawing, there is shown a pipe nipple with an annular flange 2, e.g. belonging to a pressure vessel, 0 which is to be tightness tested by feeding pressurized water a relatively high pressure, e.g. about 15 bar. The tightness tes is assumed to be performed in connection with serial productio of such pressure vessels. The coupling device 3 itself is permanently connected to a feed hose 4 which communicates with 5 a non-illustrated source of pressurized water.

The device 3 comprises a radially external cylindric casing 5, which is mechanically connectable to the flange 2 of the pipe nipple by means of an edge flange 6 extending radially inwardly 0 and complementary to said flange 2. The edge flange 6 extends about half a turn or somewhat less circumferentially, so that device can be pushed on transversally to the axis L, (from the top on the drawing) . In a mounted position, the device can be secured by means of a locking pin 7 which is rotatable about its

35 axis L-, and at each end thereof it is provided with a hook 8 and 9, respectively, for engagement with the pipe nipple flang and the casing 5, respectively. In the shown position, the lo pin 7 is in a locking position, but after rotating the same ha a turn about its axis L and displacing it to the dashed

position _r the whole device 3 can be released from the pipe ni by a transverse displacement (upwards on the drawing) . Obvious the mechanical connection and disconnection can be performed v quickly and simple. A pin 10 serves to indicate the turning po tion"of the locking pin 7 and also as a handle for the turning as well as for the pulling out and pushing in operations, respectively. A guide 12 fixed by means of a screw delimits th mobility of the pin 7 along the axis L-.

The casing 5 is axially adjoined to a second casing portion 13, which is internally screwed into the casing 5 and consists of, on the one hand, a cylindrical portion 14 having an external thread and, on the other hand, an end portion 15 having a cent end opening for a tubular coupling piston 16, onto the axially external end of which the pressurized fluid conduit 4 is mounte and fixed by a clamp 17.

The couplingpiston 16 is sealingly inserted through the end opening and extends inwardly through practically the whole device 3 and adjoins axially internally to an annular flange portion 18, which is guided and sealed at the inside of the casing 5. The annular flange portion 18 of the coupling piston comprises an annular groove 20 in its end surface 19 turned to¬ wards the pipe nipple 1, a sealing ring 21 being inserted into this annular groove. When the coupling piston is moved to the left of the drawing, the sealing ring will seal against the axially external end surface 22 of the flange 2.

The annular flange portion 18 has at least one axial through- going opening 23, which leads to an annular chamber 24 being situated radially between the outside of the tubular portion 16 of the coupling piston and the inside of the casing 5, which annular chamber is axially delimited partly by a piston surface 25 on the portion 18, partly by an annular partition wall 26. The piston surface 25 is turned away from the pipe nipple 1 and ensures that, when the pressurized fluid is fed through the hos the central opening 27 of the coupling piston 16 and the openin to the annular chamber 24, the coupling piston 16, 18 will be

exposed to an axial compressive force component, which partly or preferably totally overcomes the inevitable separating com¬ pressive force component, whereby the sealing effect between th sealing ring 23 and the flange 2 is improved.

The partition wall 26 is fixed between the casing 5 and the cyl drical portion 14 of the casing portion 13 by means of a radial ly external flange and, thus, separates the annular chamber 24 communicating with the opening 23 of the coupling piston from an axially external annular chamber 28, which is externally delimited by the casing portion 13. In this annular chamber 28 an annular actuating piston 29 is axially displaceable by means an actuating fluid, e.g. pressurized air at a pressure of about 6 bar, which is supplied via an inlet port 30 into the end por- tion 15. The internally adjoining chamber of the actuating piston 29 is vented through an outlet 31 (at the top of the drawing) .

Now, assume that the device 3 has been coupled mechanically to the pipe nipple 1 and that the actuating piston 29 is situated in an end position contacting the end portion 15. Firstly, actua ting air is supplied through the opening 30, so that the piston *-is displaced to the left into the position shown on the drawing wherein it engages with an externalshoulder surface 32 on the tubular portion 16 of the coupling piston causing the coupling piston 16,18, under the action of the actuating pressure, to sealingly contact the surface 22 of the flange 2 with the sealing ring 21. Then, when pressurized water is supplied at a rather high pressure, e.g. 15 to 20 bar, via the hose 4, the pressurized water will flow through the opening 23 into the an¬ nular chamber 24 and thereby further improve the axial contact betweenthe coupling piston 16,18 and the pipe nipple 1. Thus, no counter-pressure will be exerted by the pressurized water on the actuating piston 29.

The mechanical connection between the device 3 and the pipe nip can be modified within the scope of the inventive idea. For exa screw threads or a bayonet joint can be used. However, in case of pipe nipples having an external flange, the illustrated e bo - ^* ^ ^~ - ^E