Abstract:
The present invention concerns a gasket for quick couplers, in particular for the fluid tightness of the first valve of a male coupler. It is characterised in that it must be a composite gasket, having a toroidal shape and circumferentially comprising an O-Ring at its outer surface. 
     The gasket according to the present invention allows a number of advantages to be achieved in terms of the stability and greater reliability of the gasket, which is not subject to extrusion and crushing phenomena during the coupling and decoupling steps of the pressurised coupler.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to European Patent Application No. 15175297.9 filed Jul. 3, 2015, the entirety of the disclosures of which are expressly incorporated herein by reference, 
       STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
       [0002]    Not Applicable. 
       FIELD OF THE INVENTION 
       [0003]    The present invention relates to a gasket for quick couplers and to a quick coupler comprising this gasket. 
         [0004]    More in particular, the present invention concerns a front valve gasket of a male quick coupler. 
         [0005]    The present invention also further concerns a quick male coupler comprising this gasket. 
       STATE OF THE ART 
       [0006]    In the prior art it is known to produce male quick couplers, which are intended to be coupled to a corresponding female quick coupler, equipped with a front valve, i.e. the shut-off valve of the axial channel of the coupler, which seal is guaranteed by the presence of a torodial gasket having a circular cross section, the classic O-Ring. 
         [0007]    The situation is depicted in  FIG. 1  and in the magnification of  FIG. 1 a    while  FIG. 1 b    shows the final connecting step of the male quick coupler  100  and the female quick coupler  300 . 
         [0008]    In a male coupler  100 , the gasket  200  of a known type is placed between the hollow cylindrical outer body  110  and the valve body  120 , and therefore ensures the fluid tightness of these two elements even when the valve body  120  slides longitudinally with respect to the outer body  110 . 
         [0009]    With particular reference to  FIG. 2 , in which a connecting step of the male coupler  100  into a female coupler  300  is represented, it is noted that during the connecting step and, in particular, in the case in which there is residual pressure in the chamber in which said valve body  120  is housed, the gasket  200  is subject to a stress that tends to deform it until there is a risk that it may be guillotined, i.e. pinched between the valve body  320  of the female coupler  300  and the inner slider  310  of the female coupler itself. 
         [0010]    According to the state of the art, so as to avoid the risk of extrusion  210  of the gasket during gasket  200  operation, nevertheless, this expedient does not however prevent the problems of extrusion and crushing of the O-Ring, which deforms in the plastic field and loses all fluid tightness capacity. 
         [0011]    Considering therefore the most onerous applications for quick couplers, such as, for example, the so-called heavy duty applications “heavy duty” in the earthmoving machinery sector, quick couplers require a considerable mechanical resistance which must also be combined with a perfect seal of the coupled coupler, in all possible use positions of use and in all possible pressure conditions. 
         [0012]    There is therefore the problem of guaranteeing the seal, and thus the perfect operation of the above-identified gasket, while preventing crushing and extrusion of the gasket itself, 
         [0013]    The technical applications of the couplers that are being discussed therefore require that the gasket seal also be guaranteed under particularly onerous operating conditions. 
         [0014]    Among other characteristics that must be obtained from the gasket, this characteristic must guarantee a perfect seal regardless of the spatial orientation (horizontal/vertical) of the coupler. 
         [0015]    In addition, the gasket seal must also be guaranteed even in the presence of side load (bending phenomena) due to the weight of the pipe connected to the coupler, and in the presence of high pressure when the coupler is connected (typically meaning 350 bar and above) even in the presence of square-wave pulses. 
         [0016]    Again, a perfect seal must also be guaranteed in the presence of a vacuum when the coupler is connected (typically meaning about 755 mmHg). 
         [0017]    Again, particularly onerous usage conditions must not cause overturning or extrusion of the gasket and this also applies, for example, in the presence of high flow rates and/or square-wave pressure pulses, thanks to the particular shape of the gasket and of the corresponding seat. 
         [0018]    Moreover, the gasket should be easily replaceable in the event of damage thereto, and must have a suitable flexible &amp; deformable behaviour and abrasion and fatigue resistance properties. 
         [0019]    The gaskets of the type known in the prior art are unable to guarantee the above-mentioned operating characteristic, primarily for the following reasons. 
         [0020]    With respect to the “bending” phenomenon, i.e. the gasket sealing phenomenon, in the presence of side load due to the weight of the pipe connected to the coupler, the O-Ring gasket with anti-extrusion ring of a known type is unable to guarantee sealing, as the O-Ring is characterised by limited possibilities of recovering the compression deformation. When the coupler is subjected to side load, a part of the gasket is not subjected to compression and failure of the seal therefore occurs with consequent leakage of the working fluid. 
         [0021]    Moreover, in the presence of fluid having high pressure when the coupler is connected (typically meaning 350 bar and above) the O-Ring gasket is primarily subject to a component of the radially-oriented outward thrust. This significantly limits gasket resistance under square-wave pulse pressure conditions. 
         [0022]    Again, the O-Ring gaskets of a known type are not suitable for guaranteeing the seals in the presence of a vacuum when the coupler is connected. 
         [0023]    In the same way, when gaskets of a known type are subjected to high flow rates and/or square-wave pressure pulses, extrusion and overturning phenomena of the gasket occur. 
         [0024]    Again, the classic mixes used for O-Ring gaskets (Viton, Nitrile Rubber) do not always guarantee an adequate elastic return, tenacity and abrasion resistance. 
       SUMMARY OF THE INVENTION 
       [0025]    The technical aim of the present invention is therefore to provide a gasket which allows the above-listed conditions of efficiency and safety to be achieved and guaranteed and that makes it possible to overcome the disadvantages that afflict the gaskets of a known type, allowing greater reliability and high performance to be achieved. 
         [0026]    In the context of this aim, the object of the present invention is to provide a gasket that in particular resolves the problem of gasket extrusion, above all, but not only, in the critical transfer step of the male coupler valve  120  to the female coupler slider  310 . 
         [0027]    This aim and these and other objects that will become clearer below are achieved by a front valve gasket  1  of a male quick coupler, as claimed in the accompanying claims, which form an integral part of the present description. 
     
    
     
       LIST OF DRAWINGS 
         [0028]    Further characteristics and advantages of the present invention shall become clearer from the following detailed description, provided by way of a non-limiting example and illustrated in the accompanying drawings, wherein: 
           [0029]      FIG. 1  shows a partial cross-sectional side view with a vertical plane of a male coupler comprising a gasket of a type known in the prior art 
           [0030]      FIG. 1 a    shows a detail of  FIG. 1 , in which an enlarged view of the gasket of a known type and the anti-extrusion ring are shown; 
           [0031]      FIG. 1 b    shows a male coupler fully coupled with a female coupler; 
           [0032]      FIG. 2  shows a cross section of the critical transfer step of the seal from the male coupler valve to the female coupler slider, again in the case of a gasket of a type known in the prior art; 
           [0033]      FIG. 3  shows a perspective view of the gasket according to the present invention; 
           [0034]      FIG. 4  shows the same view as  FIG. 3 , sectionised with a vertical transverse plane; 
           [0035]      FIG. 5  shows a cross section of the same critical step of  FIG. 2  in the case in which the coupler comprises a gasket according to the present invention; 
           [0036]      FIG. 6  shows a cross section of a detail of a gasket according to the present invention housed in its own seat in a male coupler; 
           [0037]      FIG. 7  shows a cross-sectional front view of the gasket according to the present invention according to the A-A plane of  FIG. 8 ; 
           [0038]      FIG. 8  shows a plan view of the gasket according to the present invention; 
           [0039]      9   a  shows a partial cross-sectional front view of the gasket according to the present invention according to the A-A plane of  FIG. 8 ; 
           [0040]      FIG. 9 b    shows the same view as  FIG. 9 a    wherein the O-Ring has been removed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0041]    The following description illustrates a preferred embodiment of the gasket according to the present invention. This description is provided by way of a non-limiting example, therefore any variant of what has been described that can be deemed equivalent must be considered as falling within the scope of the present invention. 
         [0042]    With particular reference to  FIG. 1 , in a male coupler  100 , the gasket  200  of a known type is placed in a seat specially provided on the outer body  110 , which is a hollow cylindrical body, and the valve body  120 , and therefore ensures the fluid-tightness of these two elements even when the valve body  120  slides longitudinally with respect to the outer body  110 . 
         [0043]    With particular reference to  FIG. 2 , which represents a connecting step of the male  100  into a female coupler  300 , it is noted that during the connecting step, the seal is transferred from the valve body  120  of the male coupler  100  to the slider  310  of the female coupler  300 . 
         [0044]    This step is particularly critical in the case where there is residual pressure in the chamber in which said valve body  120  is housed. 
         [0045]    The valve gasket is subject to a stress that tends to deform it until there is a risk of it being guillotined, i.e. pinched between the valve body  320  of the female coupler  300  and the inner slider  310  of the female coupler itself, as can be seen in  FIG. 2 . 
         [0046]    With reference to  FIG. 3 , the object of the present invention is a gasket  1  having a substantially toroidal shape, comprising a main body  10  preferably made of Polyurethane (PUR) and preferably obtained by moulding process. 
         [0047]    The main body  10  of the gasket  1  according to the present invention therefore has a toroidal shape, and therefore comprises an inner surface  10   a  of the toroid  FIG. 7 , an outer surface  10   b  of the toroid  FIG. 7 , a first side surface  10   c  and a second side surface  10   d    FIG. 7 . 
         [0048]    In the cross section on a transverse plane, the gasket of the present invention has a particular, non-circular geometric profile, as shown in  FIGS. 4, 7, 9   a  and  9   b,  among others, which show the gasket according to the present invention sectionised by a transverse vertical plane. 
         [0049]    With particular reference to  FIG. 7 , the section with vertical plane A-A, indicated in  FIG. 8 , highlights the profile of the gasket  10  according to the present invention. On the transverse plane, the profile of the inner surface  10   a  is not flat, but conical, with conicity facing toward the inside of the toroid. 
         [0050]    Similarly, on the transverse plane, the profile of the outer surface  10   b  is not flat, but conical, with conicity facing toward the outside of the toroid. 
         [0051]    Preferably, and with reference to the embodiment shown by way of a non-exclusive example in the accompanying drawings, the inner surface  10   a  has a substantially triangular profile comprising two sides  10   a,  inclined with respect to the vertical, that converge in a connecting portion  10   a ″ that has a substantially flat, horizontal surface, connected to the two sides  10   a ′ by means of a fillet radius, on a transverse diametral plane. Preferably, the gasket profile is symmetrical with respect to a vertical diametral axis B. 
         [0052]    The outer surface  10   b  has a circumferential seat  12  adapted to contain an O-Ring  13 . Preferably, the outer surface  10   b  also does not have a fiat profile on a transverse vertical plane A-A, but a conical profile. The conical profile is centrally interrupted by the presence of the groove  12 . 
         [0053]    Preferably, said outer surface  10   b  has a triangular profile comprising two sides  10   b′ , inclined with respect to the vertical, and that converge in said seat  12  of said O-Ring  13 , on a transverse diametral plane. 
         [0054]    The gasket  1  according to the present invention, therefore preferably comprises an O-Ring  13  that makes the gasket more elastic and responsive to a change in operating conditions. 
         [0055]    In addition, the gasket  1  according to the present invention comprises at least one slot or flaring  11  having the function of discharging the fluid at at least one side surface  10   c,    10   d.  The addition of the slots  11  on the support flanks  10   c,    10   d  of the gasket  1  allows the side thrusts created by the oil pressure to be balanced. The situation is the one shown in  FIG. 5 , where the arrows indicate the side forces exerted by the fluid pressure. 
         [0056]    With reference to  FIG. 8 , said slots  11  preferably have a radial development on the side surfaces  10   c  and  10   d.    
         [0057]    The slots  11  are in this case arranged at 90° along the profile of the gasket, as can be seen in  FIG. 8  in particular. 
         [0058]    The gasket  1  according to the present has overall size and dimensions suitable for allowing the insertion thereof into the same seat in which the O-Ring of the type known in the prior art is housed, thereby allowing the new gasket to be used without having to modify the coupler design. 
         [0059]    The presence of the O-Ring  13  is one of the elements that most contribute to making the composite gasket  1 , object of the present invention, innovative. 
         [0060]    Indeed, among other advantages, the O-Ring  13  makes the gasket more elastic and flexible, so that it can more responsively follow the profiles of the valve body  120  of the male coupler and of the valve body  320  of the female coupler and/or of the inner slider  310  of the female coupler during their relative sliding (in the connecting &amp; disconnecting steps) thus guaranteeing fluid-tightness. 
         [0061]    The situation is outlined in  FIG. 5 , where the gasket  1 , and the inner surface  10   a  of the body  10  of the gasket in particular, is in contact with the outer surface of the valve body  320  of the female coupler  300  and with the inner slider  310 , again of the female coupler  300 , during the coupler connecting step. 
         [0062]    In all operating conditions and in the connecting and disconnecting steps, the gasket  1  according to the present invention is therefore always free of the crushing and extrusion phenomenon, under both low and high pressure. 
         [0063]    From the point of view of mechanical behaviour, the composite gasket  1 , the object of the present invention has a high tenacity and abrasion and wear resistance. 
         [0064]    These characteristics are in particular guaranteed by the material that the gasket is made of, as mentioned, preferably polyurethane, which comes into contact with the valves  120 ,  320 , and with the inner slider  310  of the couplers during the connecting and disconnecting steps, in that due to their function, the couplers are coupled and decoupled many times with repeated pressure and flow cycles. 
         [0065]    With reference to  FIGS. 7, 8 and 9   a,  we will now illustrate the function of the relief grooves  11  obtained On the sides  10   c,    10   d  of the body  10  of the gasket  1 . 
         [0066]    The presence of one or more relief grooves  11  allows the tendency of the gasket to rotate and become stuck between the moving valves during the connecting and disconnecting step of the coupler and on the varying influence of the pressure of the fluid creating leakage of the fluid and damage to the gasket itself, to be prevented. 
         [0067]    The presence of the relief grooves  11  allows the couplers to be connected and disconnected even in the presence of residual pressure within the couplers, within the male coupler in particular, as in the critical step in which the gasket comes into contact with the moving valves, it is hydraulically balanced. 
         [0068]    It has thus been shown that each technical expedient for the gasket object of the present invention contributes to achieving a specific technical result. 
         [0069]    The simultaneous presence of all the herein-described innovative characteristics allows the gasket to resolve a large number of problems that afflict the current solutions of a type known in the prior art, in the operation of the quick couplers, 
         [0070]    Each characteristic could also, in itself, entail technical advantages and therefore the gasket according to the present invention is defined in its essential characteristics by the main independent claim attached hereto, the dependent claims introducing additional characteristics that complement the invention allowing a multiplicity of technical advantages to be achieved. 
         [0071]    The gasket for quick couplers according to the present invention thus allows the drawbacks that have been left unresolved by the prior art to be overcome. 
         [0072]    In addition, a quick coupler that comprises this invention is also an object of the present invention.