Abstract:
This invention relates to a circuit breaker for an installation handling pressurized fluid comprising an internal valve, at least one joint of substanially toroidal shape being disposed in an accommodating housing around said valve and/or a member for maneuvering the valve, characterized in that the housing is connected, via at least one fluid-circulation channel, to a counter-pressure zone formed downstream of the joint around the valve or the maneuvering member. During a transitory phase of opening of the valve, a preferential flow circuit of the fluid is arranged between the housing and the counter-pressure zone through the channel. Thanks to the counter-pressure exerted on the seal, the latter does risk being dislocated with respect to its housing.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a circuit breaker for an installation handling fluid under pressure such as a gas or a liquid, in particular water, freon, an oil, etc . . . 
     2. Discussion of the Related Art 
     It is known to produce a circuit breaker comprising two elements, male and female, adapted to fit axially in each other, causing an internal valve to open. Such a valve is generally provided with an O-ring intended to ensure seal between the valve and a sealing body disposed around the valve when the valve is in closed position. 
     Such a circuit breaker is shown in accompanying FIGS. 7 to  9 , these Figures corresponding to three successive positions of the elements constituting the circuit breaker when the male and female elements are coupled. O-rings J 1  and J 2  are respectively provided, around a mobile valve C and a piston P for maneuvering this valve, to abut against sealing surfaces of a connector E or of the piston P. Taking into account the pressure P 0  prevailing around the valve C in the position of FIGS. 7 and 8, the O-ring J 1 , tends to be driven from the housing L made on the periphery of the valve C and to slide up to around the piston P, as shown in FIG. 9. A similar dislocation may occur during an opening of the circuit breaker. This operational defect is unacceptable, since the seal between the valve and the connector is in that case no longer ensured, due to the absence of the O-ring J 1 . 
     When the male connection, located to the left in FIGS. 7 to  9 , is connected to a source of pressure, while the female connection is connected to a fluid-consuming installation, the difference in pressure is reversed with respect to that shown in FIGS. 7 to  9  and the risk of dislocation principally concerns joint J 2 . 
     In any case, as soon as the difference in pressure between the two conduits connected to the male and female elements attains a critical value, one of the joints risks being ejected. This critical value depends on the fluid, on the nature of the joint and on the geometry of the elements constituting the circuit breaker. It may be less than  5  bars for circuit breakers used conventionally, with the result that the danger of ejection of a joint is present under the normal conditions of use of the circuit breaker. 
     In order to overcome this drawback, it may be provided to mold the joint in a housing of the dove-tail type, to crimp the joint or to effect an assembly with the aid of two pieces which imprison the joint. These solutions are expensive and require a more complex assembly, thus increasing manufacturing time. These solutions also render the foreseeable maintenance operations on the circuit breaker delicate. 
     It is a particular object of the present invention to overcome these drawbacks, by proposing a circuit breaker in which the risks of ejection of a joint with respect to its accommodating housing are very substantially reduced, if not eliminated. 
     SUMMARY OF THE INVENTION 
     To that end, the invention relates to a circuit breaker for an installation handling fluid under pressure comprising an internal valve, at least one joint in substantially toroidal form, or O-ring, being disposed in an accommodating housing around the valve and/or a member for maneuvering the valve, characterized in that this housing is connected, via at least one fluid-circulation channel, to a counter-pressure zone formed downstream of the joint around the valve or the maneuvering member. 
     Thanks to the invention, the pressure prevailing in the counter-pressure zone may exert on the joint an effort with a centripetal component tending to return it towards the inside of its accommodating housing, which makes it possible to balance the possible forces tending to drive the joint from its housing. 
     According to a first advantageous aspect of the invention, during a transitory phase of opening of the valve, a circuit for preferential flow of the fluid is arranged between this housing and this counter-pressure zone, through said channel. Thanks to this aspect of the invention, the counter-pressure prevailing in the counter-pressure zone presents a sufficient value to balance the supply pressure of the circuit breaker. 
     According to another advantageous aspect of the invention, the preferential flow circuit presents such a geometry that the pressure drops that it induces on the fluid during flow are less than the pressure drops induced on this fluid by a principal flow circuit of the fluid defined between the valve, the maneuvering member and/or a sealing body. Such distribution of the pressure drops guarantees the creation of a counter-pressure in the counter-pressure zone prior to the circulation of the fluid towards the downstream part of the circuit breaker during an opening of the valve, which makes it possible to create the counter-pressure before the forces on the joint tend to drive it from its housing. In that case, the principal flow circuit of the fluid may provided with obstacles adapted to increase the pressure drops induced on the fluid. Such obstacles are advantageously formed by annular grooves disposed on at least one of the opposite faces of the maneuvering member, the valve or the sealing body located downstream of the joint. 
     According to another aspect of the invention, the cross-section of passage of the preferential flow circuit is greater than the corresponding cross-section of passage of a principal flow circuit of the fluid defined between the valve, the maneuvering member and/or a sealing body. According to another approach, it may be provided that, under the same conditions, the total length of the preferential flow circuit is shorter than the corresponding length of the principal flow circuit. 
     According to another advantageous aspect of the invention, the housing is connected to the counter-pressure zone via a plurality of fluid circulation channels distributed around the axis of displacement of the valve. This multiplicity of channels allows a good distribution of the counter-pressure zone and of the effort exerted on the joint around this axis. 
     According to another advantageous aspect of the invention, the housing is connected, via at least one fluid circulation channel, to a pressurized fluid zone formed upstream of the joint. This second channel makes it possible to supply fluid under pressure to the internal volume of the housing, then the first circulation channel and the counter-pressure zone, whatever the positioning of the joint inside the housing. In that case, it may also be provided that the housing is connected to the pressurized fluid zone via a plurality of fluid circulation channels distributed about the axis of displacement of the valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be more readily understood on reading the following description of a circuit breaker in accordance with its principle, given solely by way of example and made with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic axial section of the two elements of a circuit breaker according to the invention before coupling. 
     FIG. 2 is a partial axial section of the circuit breaker of FIG. 1 during coupling in a first position. 
     FIG. 3 is a view similar to FIG. 2 with the device in a second position 
     FIG. 4 is a view on a larger scale of detail IV of FIG.  3 . 
     FIG. 5 is a view similar to FIG. 2 with the device in a third position. 
     FIG. 6 is a view similar to FIG. 4 with the device connected differently, and 
     FIGS. 7 to  9  are schematic axial sections, similar to FIG. 2, for a circuit breaker of the prior art. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring again to the drawings, the circuit breaker for hydraulic installation shown in FIGS. 1 to  5  comprises a male element A and a female element B, both provided to be tubular in shape. The male element A is formed by a connector A around which is disposed a nut  2  provided with an internal threading  3 . The connector  1  containes a valve  4  provided to abut against a convergent surface or valve seat  1   a  of the end  1   b  of the connector  1 . A spring  5 , in abutment against a circlip  6  fixed in an inner groove  7  of the connector  1 , exerts on the valve  4  an effort tending to apply it on surface  1   a.    
     A toric or substantially toroidal sealing joint seal , or O-ring,  8  is disposed in a peripheral housing  9  of the valve  4  to abut against the end  1   b  of the connector  1  in position of closure or of locking of the circuit breaker, as shown in FIG.  1 . 
     In the example shown, a conduit  10  connected to the connector  1  is connected to a pressurized source of fluid such as water, with the result that a pressure P 0  prevails inside the connector  1 . 
     As for the female element B, it is connected to a conduit  20  connected to a device using the pressurized fluid coming from conduit  10 . The female element B comprises a sleeve  21  provided with an external threading  22  provided to cooperate with the internal threading  3  of the nut  2 . In other words, by screwing the elements  2  and  21  together, the connector  1  penetrates inside the sleeve  21  in accordance with the sequence shown in FIGS. 2 to  5 . 
     The sleeve  21  contains a piston  23  of which the head  24  presents a cross-section substantially identical to that of the valve  4 , with the result that it can penetrate inside the end  1   b  of the connector  1 , pushing the valve  4  against the force exerted by the pressure P 0  and the spring  5 . 
     XX′ designates the axis of displacement of elements  4 ,  23  and  24  inside with respect to the connector  1 . 
     A counter-valve  25  is disposed around the head  24  of the piston  23 . This counter-valve undergoes an effort of thrust or force in the direction of the opening of sleeve  21 , this effort being due to an elastic return spring  26  in abutment against a washer  27  immobilized between the sleeve  21  and an end connection  20 ′ of the conduit  20  screwed on the sleeve  21 . 
     An O-ring  28 , toric or substantially toric, is disposed in a housing  29  made in the counter-valve  25  so as to abut against the outer radial surface of the head  24  of the piston  23  in the position of FIG.  1 . 
     A toric O-ring  32  is provided, near the opening of the sleeve  21  in a housing  33 , so as to abut against the outer radial surface of the connector  1  when elements A and B are coupled. 
     By screwing the nut  2  on the sleeve  21 , the connector  1  is displaced inside the sleeve  21 , pushing the counter-valve  25 , while the piston  23  may be maintained immobile with respect to the conenctor  21  to which it is kinematically connected by a rod  23   a  secured to the washer  27 . In this way, the head  24  of the piston  23  penetrates inside the end  1   b  of the connector  1  as this connector penetrates inside the sleeve  21 . 
     In accordance with the invention, the housing  9  is connected downstream of the valve  4 , i.e. to the front face of the head  24  of the piston  23 , via at least one channel  40 , two channels being shown in the Figures. Each channel  40  connects the internal volume of the housing  9  to a peripheral zone  41  defined between the outer surface of the valve  4  and the inner surface  1   a  of the connector  1 , i.e. radially around the valve  4 . Taking the foregoing into account, the pressure prevailing in zone  41  is equal, to within the pressure drops, to the pressure P 0  prevailing inside the connector  1 . 
     When the piston  23  pushes the valve  4  up to the position of FIGS. 3 and 4, the zone  41  extends up to the vicinity of the joint  8 , with the result that the pressure P 0  is exerted on the joint  8  on the downstream side thereof and produces an effort represented by arrow F in FIG.  4 . 
     The equilibrium of the forces exerted on the joint  8  by the pressure P 0  prevailing upstream and downstream of this joint has for its effect to guarantee stability thereof. It does not tend to be driven or dislocated out of the housing  9 . 
     In order to ensure that pressure P 0  or a slightly lower pressure effectively prevails in zone  41  in the position of FIG. 4, a preferential fluid flow circuit between housing  9  and zone  41  is created through the channels  40 , this preferential circuit inducing lower pressure drops on the fluid than the circuit defined between the outer radial surface of the head  24  of the piston  23  and the inner radial surface of the end  1   b  of the sleeve  1  in the positions of FIGS. 2 to  5 , i.e. during a transitory phase of opening of the valve  4 . To that end, the functional clearance between pieces  24  and  1  is smaller than the functional clearance between pieces  4  and  1 , with the result that the cross-section of passage of the circuit made between the housing  9  and the zone  41  is greater than the cross- section of passage of the circuit made between pieces  24  and  1 . 
     In practice, the preferential circuit is constituted thanks to the functional clearance between pieces  4  and  24  on the one hand,  4  and  1  on the other hand. In order to increase the apparent cross-section of passage of this preferential circuit, radial notches (not shown) may be provided at the channels  40  on the downstream face of the valve  4  or on the front face of the head  24 , these notches promoting communication of channels  40  and zone  41 . 
     The circuit produced between the channels  40  and the zone  41  is also preferential in that it is shorter than the circuit produced between the elements  24  and  1 . In effect, the bearing surface between the head  24  and the end  1   b  of the sleeve  1 , as is visible in FIG. 4, is substantially larger than the bearing surface between the valve  4  and the head  24 , with the result that, with equivalent functional clearance, the fluid would tend to head towards zone  4  rather than towards the internal volume of the sleeve  21 . 
     In order to increase further the preferential character of the fluid circuit made between the channels  40  and the zone  41 , the outer peripheral surface the head  24  may be provided with annular grooves  42  intended to form disturbances in the flow of the fluid between the elements  24  and  1   b , so as to increase the pressure drops. 
     In any case, the purpose of the preferential character of the fluid flow circuit between the channels  40  and zone  41  is to ensure that the pressure P 0 , or a pressure substantially equivalent to this pressure, serves as counter-pressure in the zone  41  to exert on the joint  8  an effort tending to return it towards the inside of the housing  9 . 
     In practice, the channels  40  of the preferential circuit are not placed under pressure as long as the joint  8  remains in place in the housing  9 , as shown in FIG.  2 . The displacement of the joint  8  towards the outside of the housing  9  then has for its effect to open the entrance of the channels  40  which are then placed under pressure, such pressurization resulting in a corresponding pressurization of the zone  41 , which has for its effect to create the effort represented by arrow F and to force the joint  8  down towards the inside of the housing  9 . In other words, it is the deformation or the displacement of the joint  8  towards the outside of the housing  9  which generates the effort of return of this joint into place. 
     Furthermore, the housing  9  is connected to the principal internal volume  1   c  of the connector  1  thanks to a plurality of channels  43  of which two are visible in the FIGURES, these channels allowing a circulation of the fluid in the direction of the channels  40  independently of the position of the joint  8  inside the housing  9 . 
     The channels  43  are advantageously disposed opposite the channels  40 , with the result that channels  40  and  43  may be made in one boring operation, parallel to axis XX′. 
     Channels  40  and  43  are advantageously regularly distributed about axis XX′ so that the counter-pressure zone  41  is supplied symmetrically about axis XX′. The effort exerted on the joint  8  thanks to the counter-pressure prevailing in this zone is thus likewise regularly distributed about this axis. 
     In practice, the number of channels  40  and  43  is included between  3  and  64 , preferably between  3  and  12 . Of course, for a circuit breaker of large diameter, the number of channels  40  and  43  might be greater. 
     Thanks to the invention, in the position of FIG. 5, the joint  8  has been forced down towards the inside of the housing  9 , while the fluid may flow in the direction of the internal volume of the sleeve  21 , as represented by arrows F′. 
     The continued movement of screwing of the nut  2  on the sleeve  21  has for its effect to displace the head  24  of the piston  23  towards the inside of the connector  1 , with the result that, taking into account the flared character of the surface  1   a , the cross-section of the fluid flow circuit between pieces  1  and  24  is increased to such a point that the pressure drops exerted on the fluid are very substantially reduced. 
     The invention has been presented with the male element A connected to a source of pressure. It is also applicable to the case of the female element B being connected to a source of pressure, while the male element A is connected to a fluid consuming device or installation as shown in FIG.  6 . 
     In order to avoid a dislocation of the joint  28  with respect to its housing  29 , channels  60  and  63  are respectively provided downstream and upstream of the joint  28 , so as to allow supply of a counter-pressure zone  61  formed radially around the head  24  of the piston  23 . 
     Under the effect of the pressure P′ 0  prevailing in the sleeve  21 , the joint  28  is displaced towards a zone of lesser pressure, i.e. in the direction of the head  24  of the piston  23 . The counter-pressure prevailing in the zone  61  exerts on the joint  28  an effort represented by arrow F″ in FIG. 6, this effort tending to push this joint towards the inside of the housing  29 . 
     As previously, the channels  60  and  63  are regularly distributed about axis XX′. Obstacles may be provided on the outer radial surface of the valve  4  in order to increase the pressure drops during the transitory phases of opening of the valve in order to create a preferential flow circuit between the housing  29  and the counter-pressure zone, through the channels  60 . 
     Whatever the mode of connection of the circuit breaker, annular grooves may also be provided on the inner surface of the end  1   b  of the element  1 . In any case, other types of obstacles intended to increase the pressure drops may be envisaged. 
     The invention has been described with reference to a circuit breaker for an incompressible or scarcely compressible fluid installation. It remains applicable for other types of installations, in particular adapted to compressible fluids such as gases. The invention may also be employed with diphasic fluids which are, as a function of the conditions of use, in liquid or gaseous form and in particular with a heat-exchanging fluid such as freon.