Abstract:
The invention is directed to a closing member of a valve, for example of a gas valve, comprising a body generally circular around a longitudinal axis and with a shoulder, a rubber seal packing disposed around the body on the shoulder and a sleeve disposed around the seal packing and the shoulder. The body comprises a longitudinally extending surface adjacent the shoulder and receiving the seal packing, the surface comprising at least one recess filled by the seal packing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention is the US national stage under 35 U.S.C. §371 of International Application No. PCT/EP2014/069973, which was filed on Sep. 19, 2014, and which claims the priority of application LU 92284 filed on Sep. 24, 2013, the content of which (text, drawings and claims) are incorporated here by reference in its entirety. 
     
    
     FIELD 
       [0002]    The invention is directed to a closing member of a shut-off valve, among others for gas under pressure, more particularly for gas under high pressure, e.g. above 150 bar. More particularly, the invention is directed to the sealing means on the closure member. The invention is also directed to a valve equipped with the closure member. 
       BACKGROUND 
       [0003]    Prior art patent document published CH 239079 discloses a closing member in the form of a mushroom, i.e. comprising an elongate portion and a shoulder portion around the elongate portion. A rubber seal packing is formed around the elongate portion and on the shoulder portion and is then vulcanised so as to properly adhere to the body of the closing member. The problem of rubber deformation and/or extrusion due to high and/or repetitive loads is neither addressed nor resolved in this teaching. 
         [0004]    Prior art patent document published BE 716804 addresses the problem of deterioration of the rubber of a closing member of the type of the preceding document by providing one or several ring shaped slots on the lateral surface of the rubber. This or these slots are intended to reduce the shearing forces exerted by the sharp edge of the shoulder portion of the body of the closing member on the elastomer material. These measures do not however solve the problem of permanent deformation or matting of the rubber at its contact surface with a valve seat. 
         [0005]    The prior art patent document published GB 908 919 discloses a valve device of the type of a water cock where the closing member comprises an elongate portion, a shoulder portion and a skirt or sleeve integral with the shoulder and forming an annular cavity receiving an annular elastomeric seal. The seal is surrounded by a sleeve slidable within the cavity. Additionally, the cavity has in its bottom face an annular recess in front of a bevelled corner of the seal so as to allow the elastomeric material to deform and move into the recess thereby increasing its effective resilience. This construction is however essentially directed to manually-operated shut-off valves, i.e. valves where the closing effort is manually exerted by means of a screw mechanism. It is intended to solve the problem of water cocks where the limited resilience of the seal has for effect after having shut-off a hot-water cock that a leakage can occur when the seal cools down. This construction is therefore not adequate for spring biased shut-off valves. 
         [0006]    Prior art patent document GB 875 446 discloses a water cock where the closing member comprises an elastomeric seal disposed on a shoulder portion and on which a sleeve is slid and crimped. Both the closing member body and the sleeve have each a ridge from which elastomeric material slightly protrude. The ridges are intended to come into contact with the seat when the valve in shut-off by a manual operation. The limited amount of elastomeric material protruding from the ridges is intended to provide an elastic contact with the seat whereas the ridges are intended to limit this elastic contact. The construction discloses in this document is clearly conceived from manually operated valves like a water cock. 
       SUMMARY 
       [0007]    The invention has for technical problem to provide a spring biased shut-off valve that is able to sustain a high number of opening and closing operations. 
         [0008]    The invention is directed to a closing member of a valve, for example of a gas valve, comprising: a body generally circular around a longitudinal axis and with a shoulder; a rubber seal packing disposed around the body on the shoulder; a sleeve disposed around the seal packing and the shoulder; wherein the body comprises a longitudinally extending surface adjacent the shoulder and receiving the seal packing, the surface comprising at least one recess filled by the seal packing. 
         [0009]    According to various embodiments, the at least one recess extends circumferentially and has a generally rounded cross-section. In various instances, the longitudinally extending surface the body comprises two such recesses. 
         [0010]    According to various embodiments, the closing member is configured so as to allow the sleeve to be slid longitudinally around the seal packing and the shoulder, the internal surface of the sleeve facing the seal packing being bevelled on the shoulder side. 
         [0011]    According to various embodiments, the internal surface of the sleeve is bevelled on at least a fifth, for instance a fourth of its length. 
         [0012]    According to various embodiments, the internal surface of the sleeve comprises a shoulder portion abutting the shoulder of the body. 
         [0013]    According to various embodiments, the sleeve comprises a skirt crimped on the external surface of the shoulder of the body, in various instances the surface is bevelled. 
         [0014]    According to various embodiments, the seal packing is fitted on the body. 
         [0015]    According to various embodiments, the seal packing comprises a front surface opposed to the shoulder, the front surface being longitudinally aligned with a front surface of the sleeve. 
         [0016]    According to various embodiments, the sleeve and the seal packing are configured so as to leave no free space between the sleeve and the seal packing. 
         [0017]    According to various embodiments, the body extends longitudinally and the shoulder forms a circular rib around the body. 
         [0018]    The invention is also directed to a valve, for example for gas, comprising: a body with an inlet, an outlet and a passage connecting the inlet with the outlet; a valve seat around the passage; a closing member movable in the passage and cooperating with the valve seat; and wherein the closing member is in accordance with the invention. 
         [0019]    According to various embodiments, the valve seat and the closing member are arranged such that the seal packing of the closing member cooperating with the seat is positioned upstream of the seat. 
         [0020]    According to various embodiments, the valve comprises a spring exerting a biasing force on the closing member in the direction of the valve seat. 
         [0021]    According to various embodiments, the spring contacts the closing member on the side of the shoulder that is opposite to the seal packing. 
         [0022]    According to various embodiments, the closing member comprises an elongate tubular portion disposed in a portion of the passage, the valve seat being upstream of the portion, on a passage shoulder of a greater diameter than the first portion. 
         [0023]    According to various embodiments, the valve seat is longitudinally distant from the surrounding portion of the passage shoulder. 
         [0024]    The invention is particularly interesting in that it provides a closing member that is able to sustain a high number of opening and closing cycles without noticeable movement, damage or permanent deformation of the seal packing. The recess(es) is/are indeed able to prevent movement of the seal packing relative to the body of the closing member. The sleeve is also able to prevent movement and/or matting of the seal packing. As a consequence it limits the elastic deformability of the seal packing. The measures of the invention allow a compensation of this undesired phenomenon and facilitate the assembly of the closing member. 
     
    
     
       DRAWINGS 
         [0025]      FIG. 1  illustrates a cross sectional view of a valve comprising a closing member, and a magnified view of the centre portion of the cross sectional view, in accordance with various embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    As can be seen in  FIG. 1  a cross sectional view of a valve is provided in accordance with the invention, the valve  2  comprises essentially a body  4  and a closing member  20 . 
         [0027]    The body  4  comprises an inlet  6 , an outlet  8  and a passage  10  connecting the inlet  6  with the outlet  8 . In the present example, the inlet  6 , the passage  10  and the outlet  8  are all aligned along the longitudinal axis of the valve  2 . In other embodiments, this can however be different. The body  4  comprises also on its external surface a conical thread  14  and a parallel thread  16  of a larger diameter. These threads  14  and  16  are intended for mounting the valve in a gas delivery installation, more particularly on a gas cylinder. In other embodiments, these threaded sections can however also be designed differently. 
         [0028]    The passage  10  forms a cavity where the closing member  20  is located. The body  4  comprises at the inlet  6  a threaded plug  12  with a through hole forming the inlet  6  as such and serving as a support for a spring  18  exerting a biasing force on the closing member  20 . 
         [0029]    The closing member  20  comprises an elongate tubular shaped body  22  with a shoulder  24 . This shoulder  24  forms a circular rib around the tubular shaped body  22 . The closing member  20  comprises also an elastomeric seal packing  26  disposed around the body  22  and on the shoulder  24 , more precisely on one side of the circular rib forming the shoulder  24 . The elastomeric seal packing  26  is surrounded by a sleeve  28  extending axially around the shoulder  24 . 
         [0030]    The valve body  4  comprises a valve seat  32  formed on a shoulder section of the passage  10 . The valve seat  32  is directed upstream and the closing member  20  is oriented so as to have its seal packing  26  directed to the valve seat  32  so as to be able to shut-off the passage  10 . The spring  18  urges the closing member  20  towards the valve seat  32  in the flow direction. In other words, in the absence of external forces or actions on the closing member  20 , the force of the spring  18  and the pressure at the inlet  6  tend to shut-off the passage  10 . 
         [0031]    The tubular body  22  of the closing member  20  extends downstream of the seal packing  26  and the valve seat  32  into a section  30  of the passage  10  that is of a reduced diameter compared to the section upstream of the seal packing  26  and the valve seat  32 . A mechanical play or clearance is present between the tubular body  22  and the section  30  of the passage  10  so as to permit a free sliding movement of the closing member  20  as well as a gas flow between the external surface of the tubular body  22  and the internal surface of the section  30 . The tubular body  22  comprises a series of holes  46  and a longitudinal and central passage  48  allowing the downstream flow of gas. The internal surface of the section  30  of the passage  10  serves also as a guiding surface for the sliding movements of the closing member body  22 . 
         [0032]    The external surface of the closing member body  22  comprises one or several recesses  34  at the place where the seal packing  26  is disposed. This or these recesses can present a wavy shape as illustrated in the drawing so as to facilitate the contact with the seal packing  26 . In various embodiments, this latter is disposed by a sliding movement along the tubular shaped body  22 . 
         [0033]    The sleeve  28  comprises an internal surface  36  contacting the seal packing  26 . This internal surface  36  can be bevelled or inclined in order to facilitate the axial insertion of the sleeve  28  around the seal packing  26 . It can also provide a volume free of material (not represented), i.e. room for elastic flow of the seal material when contacting the valve seat  32 . Indeed, it is known that elastomeric materials like rubber are mostly incompressible. In the present case, the fact that this material is surrounded by the sleeve  28  prevents it from plastic deformation and damages due to repetitive opening and closing movements. It also limits its possible deformation. The possible presence of the free space can counterbalance the effect of the protective sleeve  28  on the deformability of the seal packing  26 . 
         [0034]    The sleeve  28  comprises also a shoulder section  40  abutting the shoulder  24  of the closing member body  22 . It comprises also a skirt  42  that is crimped around the shoulder  24 , for example on a bevelled surface of the shoulder  24  that is able to retain the sleeve  28 . 
         [0035]    As can be better seen on the magnified view, the valve seat  32  is axially distant from the surrounding shoulder  44  of the passage  10 . In other words, the seat  32  protrudes somehow from the surrounding surface. The surface of this valve seat  32  is also smaller than the front surface of the seal packing  26 , thereby allowing the protruding seat  32  to penetrate into the cavity of the sleeve  28  filled with the seal packing  26 . 
         [0036]    In various embodiments, the front surface of the seal packing  26  is aligned with the corresponding front surface of the sleeve  28  so that the sleeve does not contact the valve body  4  when the closing member shut-off the passage  10  under low pressure working conditions. When applying higher pressures, the sleeve  28  can contact the valve seat  32  to achieve a mechanical stop. 
         [0037]    In various embodiments, the valve body  4  is made of metallic material like for example aluminium, brass or stainless steel. The same applies to the closing member  20 . This latter can be of a different material than the valve body  4 . In various embodiments, the sleeve  28  is also made of metallic material. 
         [0038]    The valve  2  that has been described can be used for the delivery of gas under high pressure, i.e. above 150 bars. It can be used in pharmaceutical gas mixtures containing cylinders, more particularly in portable cylinders designed for the delivery of NO/nitrogen mixtures for inhalation purposes, e.g. to prenatal babies.