Abstract:
A gas safety valve ( 1 ) capable of avoiding unwanted or inadvertent opening and possible closing, with maximum safety and allowing an opening, and possible closing, of these safety valves only through a double intentional and reliable maneuver includes a knob ( 22 ) for controlling the shutter ( 7 ) of the valve ( 1 ), during the opening and closing rotation movement, stop projections ( 32, 33 ) of the valve ( 1 ) slide on sliding segments ( 37, 38; 37 B,  38 B) provided in the knob ( 22 ) coplanar or flat-like inclined and associated to relative positioning projections ( 41, 42 ), a spring ( 28 ) housed in a chamber between a threaded end ( 19 ) of a screw ( 11 ), and a chamber ( 23 ) of the knob ( 22 ).

Description:
FIELD OF APPLICATION 
     The present invention refers to a gas safety valve, according to the preamble of claim  1 . 
     TECHNOLOGICAL BACKGROUND AND STATE OF THE ART 
     Gas safety valves are usually used in gas distribution systems to safely avoid gas leakage, and possible ensuing damage, in case of incorrect handling. 
     Such safety valves have a ball shutter and a control rotation member in form of a knob with one or two gripping fins, or a lever or the like, where solely the representative term of a knob will be used hereinafter for the sake of simplicity. Such knobs are generally rotatable for a ninety-degree rotation to rotate the ball shutter from the opening position to the closing position and vice versa. 
     Gas safety valves are known in different embodiments, which provide for a control with a double manoeuvre, as required for example in the United States for the so-called latching-type valves. 
     A valve of this type is disclosed, for example, in documents IT-A-1.346.153 and U.S. Pat. No. 7,178,781 B2 on behalf of the Italian company Valvosanitaria Bugatti S.p.A. 
     These known valves have the common characteristic of requiring various additional components with respect to the conventional valves and provide for a double control manoeuvre comprising, starting from the valve in closed position, a first axial movement of lowering the knob countering a spring and the subsequent rotation of the knob by 90° to take the knob/shutter to the opening position. 
     It is clear that, considering the brief rotation for opening the valve by 90°, the only guarantee of safety against inadvertent opening is provided by the compression pressing on the knob, which actually may also be caused inadvertently for various reasons both by the installers, users, other people or household animals. In a known case of opening a safety valve of this type was actually caused by a dog which lay on the knob pressing it with its weight and then rotating it by rubbing it with the movement thereof. 
     Furthermore, such known safety valves are not capable of equally providing a safety of a shutter in opening position, as required at times, hence they cannot exclude inadvertent partial or full closing movements of the valve. 
     SUMMARY OF THE INVENTION 
     The present invention proposes to provide a gas safety valve capable of avoiding unwanted or inadvertent opening and possible closing, with maximum safety and allowing an opening, and possible closing, of these safety valves only through a double intentional and reliable manoeuvre. 
     This task is obtained, according to the invention, by means of a gas safety valve having the characteristics of claim  1 . 
     Further developments of the proposed gas safety valve are observable from the characteristics described in the dependent claims. 
     The gas safety valves according to the invention allow attaining various and considerable advantages. 
     First and foremost a compression or force action on the knob does not cause any movement thereof, even in case of pressure with considerable force. Another advantage lies in the fact that with respect to the conventional ball valves the disclosure of the present invention solely requires limited modifications of the knob and of the screw connecting said knob with the ball shutter, while such modifications of the knob can be obtained directly through the casting of the knob, both made of metal and synthetic material, hence, besides the need for a new casting, there are no additional costs and, regarding the screw there is only required a considerable extension of the upper threaded end thereof, hence the increase of the production costs is entirely negligible. Only one additional component made of a simple conventional spring is provided for. 
     The removable positioning means and the means for fastening the screw into the neck of the body valve remain entirely unvaried, given that the body may be provided in any embodiment at will, as illustrated for example in the U.S. Pat. No. 4,714,236 A. 
     A further advantage lies in the fact that locking the spring in the housing chamber thereof does not require additional components, given that the head of the same screw provided previously for locking the knob onto the screw is used. 
     The disclosure of the present invention can be applied onto any embodiment of the knob, or control member, where on the knob there can be preferably advantageously provided a gripping projection safely facilitating the first movement of the double opening, and possibly closing, manoeuvre, or a brief axial lifting movement. 
     Furthermore, there should be observed a further advantage according to which the valves according to the invention in the opening position thereof are not locked in any manner whatsoever, hence the closing manoeuvre thereof may be performed any time in a simple manner and with maximum speed, such solution representing a very important advantage in terms of safety. According to the invention, with the valve open the spring may remain, depending on the embodiment, compressed or released. 
     Furthermore, according to the invention there is advantageously provided an embodiment requiring the knob to be lifted to pass from the open position to the closed position and vice versa as required in various fields of application wherein there is required the safe lifting of the knob also to pass from the opening position to the closing position. 
     A further advantage lies in the fact that the mechanical lock is guaranteed by a particular configuration directly provided for within the knob and which allows the elastically preloaded housing of the two stop projections formed on the neck of the valve body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics advantages and details of the gas safety valve according to the invention, as well as of the implementation thereof, will be clearer from the following description of some preferred embodiments of such gas safety valves illustrated purely by way of non-limiting example in the attached drawings, wherein: 
         FIG. 1  is an exploded view of a gas safety valve according to the invention, 
         FIG. 2  is a bottom perspective view of the control knob, 
         FIG. 3  is a bottom view of the knob of  FIG. 2 , 
         FIG. 4  is a sectional view according to plane A-A in  FIG. 3 , 
         FIG. 5  is a sectional view according to plane B-B in  FIG. 3 , 
         FIG. 6  is a median longitudinal section according to plane A-A in  FIG. 7  through the assembled valve of  FIG. 1  in the closed position, 
         FIG. 7  is a median cross-section according to plane B-B in  FIG. 6 , 
         FIG. 8  is a bottom view of the knob in the section according to plane C-C of  FIG. 7 , 
         FIG. 9  is a median longitudinal section according to plane A-A in  FIG. 10  through the assembled valve of  FIG. 1  in the open position, 
         FIG. 10  is a median cross-section according to plane B-B in  FIG. 9 , 
         FIG. 11  is a bottom view of the knob in the section according to plane C-C of  FIG. 10 , 
         FIG. 12  is a bottom perspective view of a second embodiment of the control knob, 
         FIGS. 13 and 14  each show a sectional bottom view analogous to  FIGS. 8 and 11  with shutter, or knob, respectively in the opening and closing position, 
         FIG. 15  is a bottom perspective view of a variant of the knob of  FIG. 2 , and 
         FIGS. 16 ,  17  and  18  each show a perspective view of the knobs having handgrip portions to guarantee a firm gripping of the knobs facilitating the lifting movement thereof. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In various figures identical parts have identical reference numbers. 
     First, reference is made to  FIG. 1 , in which a gas safety valve according to the invention is indicated in its entirety with  1  and it has a valve body  2  having a through conduit  3  with an inlet  4  and an outlet  5 , or vice versa, same case applying to an intermediate chamber  6 ,  FIG. 6 , in which there is rotatably and sealingly housed a ball shutter  7  with a through hole  8 . The ball shutter  7  has—at the upper part—a seat  9 , for example a fissure, in which the lower end  10 , for example in form of a tang, of a control screw  11  is engaged. This screw  11  is rotatably sealingly housed and axially not displaceable in a portion of neck  12  of the valve body  2 . For such purpose there are provided removable positioning means formed, in the illustrated example, by a sealing ring  13 , by a metal ring  14  flared at the top part and by an elastic metal ring  15  provided with slots which can be housed in a groove  16  formed in the neck  12  of the valve  1 . A sealing O-ring housed in a groove  18  made in the screw  11  is indicated with  17 . The screw  11  has—at the upper part—a threaded end  19  in which, in the known valves, there can be screwed a screw which traverses a hole provided in a control knob to lock said knob on the screw. The required 90 degree rotation movement to move the shutter  7  from the closing position to the opening position, and vice versa, is determined by a pair of stop projections provided on the neck and by a pair of positioning projections provided on the knob, as per se known in various implementations, for example in the U.S. Pat. No. 4,714,236 A. 
     At the upper part of the screw  11  there is a profiled enlargement  20  which can be housed in a corresponding profiled hole  21  provided in the control knob  22 . 
     The present invention according to whose disclosure for the double manoeuvre of axial lifting and rotation of the knob to pass the ball shutter from the opening position to the closing position and vice versa, intervenes at this point, substantially maintaining the known embodiments of the ball valves unvaried and providing few and simple modifications solely concerning the upper end of the screw and of the knob, as well as the use of a simple spring and a different use of the known knob-screw stop screw. 
     Regarding the knob  22  it has a known through hole ( 23   b ) in form of a first circular seat  23  having a bottom  23   a  and defining with the upper threaded end  19  of the screw  11  an annular chamber  25 ,  FIG. 6 , whose circular seat  23  terminates—at the upper part—with a enlargement  26  defined by a collar  27 . The annular chamber  25  houses a spring  28 , one of whose ends rests on the bottom  23   a  of the circular seat  23  and whose other end rests on the lower side of the head  29  of the screw housed in the threaded hole of the upper end  19  of the screw  11 . Thus, the knob  22  may be slightly lifted axially by traction from the screw  11  countering the elastic force of the spring  28 . 
     Regarding the body  2  of the valve, the two stop projections of the rotation movement of the shutter  7  are provided in the known manner in form of two fins  32 ,  33  projecting upwards from the upper edge of the neck  12  and correspondingly rounded, whose upper side  32   a  and  33   a , preferably smoothened or rounded at the corners, now constitutes a sliding side, as illustrated hereinafter. 
     As observable in particular from  FIGS. 2-5 , within the knob  22  the profiled seat  21  housing the profiled enlargement  20  of the screw  11  is obtained within a crown  34 , which forms—with the outer wall  35  of the knob  22 —an annular chamber  36  with a bottom or roof  36   a . On this bottom  36   a  there are formed two opposite circular segments  37 ,  38 , which, with respect to the bottom  36   a , have a sliding plane  31 , whose planes  31  in  FIG. 2  are coplanar and form a step  36   b  with respect to the said bottom  36   a.    
     As observable in  FIGS. 2 and 3 , at the other end of the said circular segments  37  and  38  in the knob  22  there is respectively formed a positioning projection  41  and  42  with an inner abutment side  41   a  and  42   a  and an end  41   b  and  42   b , whose ends  42   b  and  41   b  alongside the respectively opposite sides  37   a  and  38   a  form two opposite seats  39  and  40 , into which the projections  32  and  33  enter when the knob  22  and the shutter  7  are at closing position. 
     This first embodiment of the gas safety valve  1  according to the previously described embodiment operates as follows: 
     when the valve  1  is at the closing position,  FIGS. 6-8 , the projections  32 ,  33  on the neck  12  of the valve are housed in the seats  39 ,  40  of the knob  22 , which is pushed downwards by the spring  28 , and the step or thickness of circular segments  37 ,  38  prevents the rotation movement of the knob  22  both clockwise and anticlockwise. The distance between the longitudinal axis  43  of the valve and the lower side  44  of the knob  22  is indicated with X when the valve  1  is closed,  FIG. 6 , and with Y when the valve is open,  FIG. 9 , where Y&gt;X by a degree slightly greater than the step or thickness of the circular segments  37  and  38 . 
     The valve  1  is opened by gripping the knob  22  and lifting it axially upwards by a degree such to allow the upper or sliding sides  32   a  and  33   a  of the projections  32  and  33  to be beneath the coplanar plane  31  of the two circular segments  37  and  38 , hence allowing a 90° rotation of the knob  22  in the opening direction delimited by the inner abutment sides of the positioning projections  41  and  42 , where rotation in the opposite direction is hindered by the ends  41   b  and  42   b  of the abutment projections  41  and  42 . Thus, lifting the knob  22  allows a 90° opening rotation of the knob  22 , wherein in this rotation movement the upper sides  32   a  and  33   a  of the projections  32  and  33  will slide beneath the sliding circular segments  37 ,  38 . At the end of the opening rotation, the knob  22  is released and the projections  32 ,  33  rest with the upper sides  32   a  and  33   a  thereof on the circular segments  37  and  38  maintaining the knob  22  at a lifted position, with the spring  28  compressed. 
     The valve is closed by simply rotating the knob  22  clockwise, where the projections  32  and  33  slide with the upper sides  32   a  and  33   a  thereof on the flat circular segments  37  and  38  until, at the end of the 90° closing rotation, said projections  32 ,  33  are beneath the seats  39  and  40  until the spring  28  pushes on said projections  32  and  33  with an expansion action and with an automatic lowering of the knob  22  in the closing position thereof,  FIG. 6 . It should be observed that in this embodiment the closing rotation movement may be performed in an extremely quick manner and without any jamming, this being a very important aspect in various cases of use specifically for a safe and quick closure of the valve. 
     Alternatively, according to the invention, in order to prevent the spring  28  form remaining constantly compressed in the position of closing the valve  1  it is proposed to configure the circular segments  37 ,  38  in form of inclined wedge-like planes  37 B and  38 B,  FIG. 12 , with inclination increasing from the opening position towards the closing position where they terminate forming a step  44 , which in turn forms with the adjacent end of the positioning projection  41 ,  42  a seat  45 ,  46  for respectively housing one of the two stop projections  32 ,  33  of the neck  12 , as illustrated in  FIG. 12 , or like in  FIG. 13  with the knob  22  at the open position and—in FIG.  14 —at the closed position, wherein the stop projections  32  and  33  remain on the bottom  36   a . Also in this case, the closing rotation movement may occur in a quickly and immediate manner. 
     According to a third embodiment of the valve  1 ,  FIG. 15 , in the knob  22  said two sliding circular segments  37 ,  38  coplanar, as illustrated in  FIG. 15 , or wedge-shaped, provide for the reduction of the thickness thereof up to the said bottom  36   a  of a section  47  of the end thereof near the adjacent to the positioning projection  41 ,  42  of the knob  22  so as to create a respective seat  47  for housing the said stop projections  32  and  33  of the valve  1  with shutter/knob reaching the opening position, where in this case also the beginning of the closing movement requires a preliminary lifting of the knob. 
     In order to guarantee safe gripping of the knob  22  and lifting thereof countering the spring  28  the knob may advantageously have suitable gripping portions  48  as illustrated for example in  FIGS. 1 ,  16 ,  17  and  18 . 
     From the structural and functional description of the gas safety valves according to the invention it is observed that the disclosures of the invention allow efficiently meeting the proposed object and attaining the previously mentioned advantages. 
     In practice, those skilled in the art may introduce various modifications or variants, such as for example provide for the projections on the neck of the valve and the abutment projections of the knob respectively outside the neck and knob, or provide for other configurations of the screw and/or the removable positioning means thereof and so on and so forth, without departing from the scope of protection of the present invention as defined in the claims that follow.