Abstract:
An emergency shutoff valve includes a fluid conduit having a frangible area defined therein, a valve member operatively coupled to said conduit upstream of the frangible area, an expansible chamber having the frangible area defined therein, a movable member defining at least a portion of the expansible chamber, and a linkage operatively coupled to the movable member and the valve member for shutting the valve upon movement of the movable member in response to leakage of fluid through the frangible area. A method of shutting off fuel includes defining an expansible chamber about a frangible area in the conduit, moving a member defining a portion of the expansible chamber in response to leaking fuel, and shutting off a fuel valve in response to moving the movable member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/553,067, filed on Oct. 26, 2006, now U.S. Pat. No. 7,578,308, the entire disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to valves, and more particularly to emergency shutoff valves for use in fuel dispensing systems. 
     BACKGROUND 
     Fuel dispensing systems used at retail gas stations typically include an underground tank containing gasoline, diesel fuel or other liquid fuels, an above ground dispensing unit terminating in a nozzle adapted to supply the fuel to a motor vehicle, and a piping system interconnecting the underground tank and dispensing unit. While infrequent, vehicles can collide with the dispensing unit, causing the dispensing unit to be displaced. It is also possible for the unit to be displaced due to certain environmental conditions. In either event, a fuel pipe or conduit may rupture, causing fuel to be spilled and creating a potentially hazardous condition, unless preventive measures are taken. 
     A variety of emergency fuel shutoff valves are known in the art that have been developed in response to the foregoing potential problem. Known valves of this type include those having upper and lower housings releasably connected to one another, with the lower housing rigidly mounted. For instance, the lower housing can be mounted within a sump located beneath a concrete pedestal supporting the dispensing unit using, for example, a mounting bar as is known in the art. The lower housing is operably connected to the underground tank via underground conduits, while the upper housing is operably connected to the fuel dispensing unit. 
     A weakened portion, such as a circumferential groove, formed in the upper housing provides a planned failure site so that a first portion of the valve can separate from a second portion of the valve when one of the first or second portions is subjected to a predetermined load. Such a separation of valve portions causes a valve element in the lower housing to move from a releasably latched open position to a closed position, shutting off the flow of fuel from the underground tank. Shutoff valves of this type may also include a check valve in the upper housing that closes under the action of a biasing member when the valve portions separate. The check valve may reduce or prevent the backflow of fuel from the dispensing unit. 
     Emergency shutoff valves of the foregoing type have been successfully used in fuel dispensing systems, but they can exhibit certain disadvantages. For instance, it is possible for the dispensing unit to be subjected with a load or force that is not sufficient for the first portion of the shutoff valve to be separated from the second portion of the valve, but is sufficient to compromise the structural integrity of the valve housing. In other words, a load may crack the valve housing along the groove without completely separating the valve portions on either side of the groove. In this event, the valve element in the lower housing may not close, which may permit fuel to escape from the housing through the cracked or otherwise damaged weakened portion of the valve, resulting in undesirable spillage of fuel to the environment. 
     It is therefore desirable to provide an emergency shutoff valve for use in fuel dispensing systems that overcomes the disadvantages associated with known emergency shutoff valves. 
     SUMMARY 
     To these ends, an embodiment of the invention contemplates an emergency shutoff valve having a frangible, or weakened portion or other form of predetermined failure area disposed within or forming a portion of an expansible chamber. Any leak from this frangible area, such as might occur from an impact to a fuel dispenser or due to certain environmental conditions, actuates a movable member which defines at least a portion of an expansible chamber, and this movement is operatively coupled to the valve so as to cause it to shut off. Accordingly, fuel leaks from impact or valve trauma less than full valve compromise, i.e., cracking the valve without fully shearing or separating the valve, may be contained or reduced through valve shut off. 
     More particularly, an emergency shutoff valve according to one embodiment of the invention is provided for use in a fuel dispensing system. The emergency shutoff valve comprises a housing defining a fluid inlet, a fluid outlet and a fluid flow passage extending between the fluid inlet and the fluid outlet. The flow passage may be suitable for the flow of fuel therein. The valve may further include a valve element movable within the housing between an open position, in which fuel is permitted to flow between the fluid inlet and outlet, and a closed position, in which fuel is prevented from flowing between the fluid inlet to the fluid outlet. A latching mechanism may be coupled to the valve element and the housing to releasably latch the valve element in the open position. The valve may also include an expansible member defining at least a portion of a sealed expansible chamber external of the housing. The housing comprises a weakened portion downstream of the valve element and the expansible chamber is sealed to the housing at a first location upstream of the weakened portion and at a second location downstream of the weakened portion so as to bound or enclose the weakened portion. The emergency shutoff valve defines a failure mode wherein the structural integrity of the housing is compromised to an extent wherein fuel may escape from the housing through a crack in the weakened portion and into the expansible chamber when a predetermined load is applied to the housing. Upon occurrence of the failure mode, the expansible member is operable for uncoupling the latching mechanism from at least one of the housing and the valve element, wherein the valve element moves from the open position to the closed position to stop the flow of fuel through the valve. In particular, the pressure in the fuel line causes fuel to flow into the expansion chamber through the crack in the weakened portion of the housing so as to actuate the expansible member thereby causing the valve element to move to the closed position. 
     In other embodiments, the emergency fuel shutoff valve may include one or more of the following features. In some embodiments, the expansible member may comprise a sleeve, made of an elastomeric material, disposed in surrounding relationship with the housing. The valve further may include a rotatable shaft having one end projecting outwardly from the housing, with the valve element being coupled to the shaft for rotation therewith. A biasing member cooperates with the shaft to bias the valve element toward the closed position. 
     The latching mechanism may be a linkage. In one embodiment, the linkage includes first and second links, each having proximal and distal ends, with the proximal end of the first link being coupled to the housing and the distal end of the first link being coupled to the proximal end of the second link. The distal end of the second link may be coupled to the end of the rotatable shaft that projects outwardly from the housing. In this embodiment, the expansible member is operable for contacting and moving the first link upon occurrence of the failure mode, wherein the first link is uncoupled from one of the housing and the second link, and wherein the valve element is unlatched and moves from the open position to the closed position. The first link may include a protruding portion disposed between the proximal and distal ends of the first link and protruding toward the expansible member. 
     Alternatively, the first link may include a first link portion and a second link portion each pivotally coupled to the housing. The first link portion may include a notch and the second link portion may include a first, second and third arm. The proximal end of the second link may include a pin that is received in the notch of the first link portion when the valve element is releasably latched in the open position. The distal end of the second link may be coupled to the end of the rotatable shaft that projects outwardly from the housing. The second arm of the second link portion may extend generally tangentially relative to the housing proximate the expansible member. In this embodiment, the expansible member is operable, upon occurrence of the failure mode, for contacting the second arm, causing the first link to rotate and the pin to become disengaged from the notch in the first link portion, wherein the valve element is unlatched from the open position and moves to the closed position. 
     In another embodiment, the valve may further comprise an annular member at least partially circumscribing the housing and a hollow protruding member integral with the annular member and extending away from the housing. In this embodiment, the expansible member may comprise a diaphragm made of an elastomeric material and the expansible member can be disposed in sealing engagement with the protruding member. The linkage may comprise first and second links coupled to one another. The first link may be coupled to the housing at its proximal end and coupled to the proximal end of the second link at its distal end. The distal end of the second link may be coupled to the end of the rotatable shaft that projects outwardly from the housing. In this embodiment, the expansible member is operable for contacting and moving the first link upon occurrence of the failure mode wherein the first link is uncoupled from one of the housing and the second link, and the valve element is unlatched and moves from the open position to the closed position. 
     The weakened portion of the housing may take a variety of forms. In one embodiment, it is a circumferential groove. At least a portion of the groove can be generally V-shaped. The expansible member may be made of any suitable material, including those selected from the group consisting of fluro silicone rubber, BUNA-N rubber, fluro elastomer rubber or other suitable materials. 
     The housing preferably includes a lower housing and an upper housing secured to one another, with the lower housing adapted to be mounted within a sump beneath a dispensing unit and further adapted to be operatively coupled to a source of pressurized fuel. The upper housing preferably includes the weakened portion and may be adapted to be coupled to a fuel pipe within the dispensing unit. The valve element is preferably disposed within the lower housing, upstream of the weakened or frangible portion of the valve. 
     The emergency shutoff valve may further include a normally open, second valve element disposed within the upper housing and a biasing member biasing the second valve element toward a closed position. 
     According to another aspect of the invention, a method is provided for isolating a leak in a fuel dispensing system. The method comprises providing an emergency shutoff valve for use in the fuel dispensing system, with the valve comprising a housing with a weakened portion therein, and the housing defining a fluid inlet, a fluid outlet and a fluid flow passage therebetween. The valve further comprises a valve element movable between an open position and a closed position. The method further comprises providing a linkage coupled to the valve element and the housing, wherein the linkage releasably latches the valve element in the open position. Additionally, the method comprises defining at least a portion of an expansible chamber with an expansible member sealed to the housing at locations upstream and downstream of the weakened portion, wherein the expansible member is operable, upon occurrence of a fuel leak from the fluid flow passage through the weakened portion and into the expansible chamber, for uncoupling the linkage from at least one of the housing and the valve element, wherein the valve element is unlatched and moves from the open position to the closed position to stop the flow of fuel through the valve. 
     Stated in another way, the method comprises the steps of defining a frangible area in a fluid conduit downstream of a cut-off valve, and disposed within an expansible chamber sealed to the conduit downstream and upstream of the frangible area, and closing the valve upon movement of an expansible member forming at least a portion of the expansible chamber in response to leakage of the fluid through the frangible area. In one aspect of the invention, the pressure in the fuel line is sufficient to actuate the expansible member so as to close the valve when a leak occurs along the weakened or frangible area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying drawings wherein: 
         FIG. 1  is a schematic illustration of a fuel dispensing system that incorporates an emergency shutoff valve according to an embodiment of the present invention; 
         FIG. 2  is a perspective view of the emergency shutoff valve shown schematically in  FIG. 1 ; 
         FIG. 3A  is a cross-sectional view taken along line  3 A- 3 A in  FIG. 2 , with a valve included in the lower housing shown in an open position; 
         FIG. 3B  is a cross-sectional view similar to  FIG. 3A , but with a failure mode associated with a weakened portion of the emergency shutoff valve illustrated; 
         FIG. 3C  is a cross-sectional view similar to  FIGS. 3A and 3B , further illustrating the failure mode shown in  FIG. 3B ; 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  in  FIG. 2 ; 
         FIG. 5  is a perspective view of an emergency shutoff valve according to another embodiment of the present invention; 
         FIG. 6A  is a cross-sectional view taken along line  6 A- 6 A in  FIG. 5  illustrating the included linkage of the shutoff valve in a position that latches a valve element (not shown in  FIG. 6A ) in the lower housing in an open position; 
         FIG. 6B  is a cross-sectional view similar to  FIG. 6A , but with the included linkage in a position that unlatches the valve element in the lower housing (not shown in  FIG. 6B ), allowing it to move to a closed position; 
         FIG. 7  is a perspective view of an emergency shutoff valve according to another embodiment of the present invention; and 
         FIG. 8  is a cross-sectional view taken along line  8 - 8  in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic illustration of a fuel dispensing system  10  that incorporates an emergency shutoff valve  20  according to the present invention. The fuel dispensing system  10  includes a source of fuel  22  having fuel  24  contained therein. As shown in  FIG. 1 , the source  22  of fuel may be an underground fuel tank, such as that used at a retail gas station for instance. The fuel dispensing system  10  may further include a stand pipe extending into the fuel tank, a sump  26 , various flow control and flow measurement devices (not shown) and a section of piping  28  that is mechanically and fluidicly coupled to valve  20 . Valve  20  comprises a housing, or fluid conduit,  30  that may include first  32  and second  34  housings that are removably secured to one another by conventional means, such as fasteners  36  shown in  FIG. 2 . While the preferred embodiment described herein includes two separate housings  32 ,  34  coupled together, the invention is not so limited as the valve  20  may have a one-piece housing. The two-piece structure allows the second housing  34  (which has the shear groove) to be replaced without also replacing the first housing  32 . In the illustrated embodiment, the first housing  32  is a lower housing and the second housing  34  is an upper housing. The terms upper and lower are used to describe embodiments and to facilitate understanding of the invention and does not limit the invention to a certain orientation. Fuel system  10  may further include a fuel dispensing unit  38  that may be mounted on a pedestal  40 , which may be made of concrete and which in turn may be mounted on a surface, such as, for example, a concrete surface of a retail gas station. The lower housing  32  may be rigidly mounted within a sump  41  below or adjacent the pedestal  40 . 
     The fuel dispensing system  10  may further include a rigid pipe or conduit  42  that may extend upwardly through the interior of the dispensing unit  38 . Pipe  42  may be mechanically coupled, at a lower end, to the upper housing  34  of valve  20  and is in fluid communication with valve  20 . Pipe  42  may also be in fluid communication with a flexible hose  44  that terminates in a nozzle  46  that is adapted for dispensing fuel into the fuel tank of a motor vehicle, such as an automobile, truck, etc. 
     Referring now to  FIGS. 2-4 , housing  30  of valve  20  generally defines a fluid inlet  50 , a fluid outlet  52  and a fluid flow passage  54  extending between the fluid inlet  50  and the fluid outlet  52 . The fluid flow passage  54  may be suitable for the flow of pressurized fuel therein, such as fuel  24 . The fuel  24  may be pressurized by a pump (not shown) included in the fuel dispensing system  10 . 
     Valve  20  includes a valve member  60  that may be a flapper or butterfly type valve and which may be movably mounted within the lower housing  32 . Valve member  60  includes a valve element  62  that is movable between an open position shown in  FIGS. 3A ,  3 B and in solid line in  FIG. 4 , and a closed position shown in  FIG. 3C  and in phantom line in  FIG. 4 . In the closed position, the valve element  62 , such as a sealing disk, may be disposed in sealing engagement with a valve seat  64  and is adapted to cut off or prevent fuel flow from the fluid inlet  50  to the fluid outlet  52 . The valve element  62  may be supported by a structure, indicated generally at  66 . Additional details of the structure  66  that can be used are found in U.S. Pat. Nos. 5,454,394; 5,193,569; and 5,099,870 that disclose conventional shear valves. Each of these patents is assigned to the assignee of the present invention and is expressly incorporated by reference herein in its entirety. The support structure  66  may include a pair of arms  68  having square openings that are received by a square section of a rotatable shaft  70 , such that the valve element  62  and supporting structure  66  rotate with shaft  70 . Valve element  62  and supporting structure  66  may be biased toward the closed position by a biasing member  72 , which can be a torsion spring, coiled about the shaft  70 . However, the valve element  62  and associated support structure  66  may be releasably latched in the open position by a latching mechanism indicated generally at  74  in  FIG. 2 . In the illustrated embodiment, latching mechanism  74  may be a linkage. However, latching mechanism  74  may be other devices suitable for releasably latching valve element  62  in the open position. During normal operation of valve  20 , i.e., not during a failure mode of valve  20 , the linkage  74  may be coupled to both the valve element  62  and to housing  30  as explained in more detail below. 
     Linkage  74  may include a first link  76  having a proximal end  78  coupled to housing  30 . In the illustrated embodiment, this is accomplished by a pin  80  secured at one end to housing  30  and having an opposite end extending through an aperture formed in the proximal end  78  of first link  76 . First link  76  further includes a distal end  82  that is coupled to a proximal end  84  of a second link  86  of linkage  74 . A distal end  88  of second link  86  may be coupled to an end  90  ( FIG. 3A ) of the rotatable shaft  70  that projects outwardly from the housing  30 . First link  76  may also include a protruding portion  92  that is disposed between the proximal  78  and distal  82  ends of first link  76  and is used for a subsequently discussed purpose. 
     The outer end  90  of the rotatable shaft  70  may include a cylindrical portion and the distal end  88  of second link  86  may include a circular aperture formed therein that engages the cylindrical portion of the outer end  90  of shaft  70 . The distal end  88  of second link  86  may be secured to the outer end  90  of shaft  70  by soldering for instance, with the solder having a relatively low melting point. Accordingly, in the event of a fire surrounding valve  20 , the solder can melt, allowing shaft  70  to rotate within second link  86 , thereby causing the valve element  62  and supporting structure  66  to move from the open position shown in  FIGS. 3A and 3B  and in solid line in  FIG. 4 , to the closed position shown in  FIG. 3C  and in phantom line in  FIG. 4 , under the action of the biasing member  72 . Alternatively, and in accordance with another embodiment of the invention, instead of the distal end  88  of the second link  86  being configured as a fusible hub that releases the valve element  62  in the event of a fire, as is conventional, the first link  76  may include a fusible section intermediate the proximal and distal ends  78 ,  82 . Thus, in the event of a fire, the fusible section melts separating the end  78 ,  82  of the first link  76  and allowing the valve element  62  and supporting structure  66  to move to the closed position under the action of biasing member  72 . Implementing the fusible section in the first link  76  may provide certain cost and manufacturing advantages as compared to the traditional placement of a fusible section in the distal end  88  of the second link  86 . 
     Housing  30  includes a weakened, or frangible, portion  94  formed therein that is downstream of valve member  60 . In the illustrated embodiment, upper housing  34  includes the weakened portion  94  formed therein, which extends circumferentially around a perimeter of the upper housing  34 . The invention, however, is not so limited. The weakened portion  94  may be a groove and can have an inner portion  96  that is generally V-shaped, as shown in the illustrated embodiment. The invention is not so limited as those of ordinary skill in the art will recognize other configurations that define the weakened portion  94 . The weakened portion  94  defines a predetermined fracture of failure site for various failure modes as subsequently discussed. 
     In an exemplary embodiment, valve  20  may further include an expansible member  100 . The expansible member  100  may be a sleeve disposed in surrounding relationship with the weakened portion  94 , as shown in the illustrated embodiment, and member  100  may be made of an elastomeric material. Suitable materials include fluro silicone rubber, BUNA-N rubber and fluro elastomer rubber. However, other materials may be used provided they exhibit sufficient resistance to ozone, to prevent dry rot, and are resistant to fuel corrosion. The expansible member  100  generally surrounds the weakened portion  94  and may be sealed to the upper housing  34  at a first location  102  upstream of the weakened portion  94  and at a second location  104  downstream of the weakened portion  94  so as to bound or encompass weakened portion  94 . The expansible member  100  may be sealed to the upper housing  34  by a pair of band clamps  106  that extend around the perimeter of upper housing  34  or other suitable devices such as straps and the like. The expansible member  100  defines at least in part an expansible chamber  108  best seen in  FIGS. 3B and 3C . The function of the expansible member  100  is subsequently discussed. 
     Valve  20  may optionally include a second valve member  110  disposed within the upper housing  34  of valve  20 , downstream of the weakened portion  94 . Valve member  110  may, for example, be a spring loaded poppet or check valve having a valve element  112  that may be a sealing disk. Valve member  110  may be normally open and held in the open position during operation of valve  20  by an abutment structure indicated generally at  114  that is secured to the upper housing  34 . Other details of valve member  110  and the configurations of abutment structures  114  that may be used are more fully discussed in U.S. Pat. Nos. 5,454,394; 5,193,569; and 5,099,870 referenced previously, which disclose similar poppet valve and abutment structures. Alternatively, valve member  110  may be held in an open position during normal operation of valve  20  by the pressure of the fuel flowing within valve  20 . Valve member  110  may be biased toward a closed position by a biasing member  116  that may, for example, be a coil spring. In the closed position, the valve element  112  is disposed in sealing engagement with a valve seat  118  formed in the upper housing  34 . Valve member  110  may be forced closed by biasing member  116  in the event of certain failure modes, as subsequently discussed. Valve  20  may also optionally include a pressure relief valve (not shown) that can be disposed in a tubular stem  120  of valve member  110 . The features of relief valves that may be used are discussed in the previously referenced patents. In any event, the pressure relief feature prevents a large pressure build up in the piping above the valve  20  on the occasion that the valve is sheared or separated. 
     Since the lower housing  32  of valve  20  is rigidly mounted within sump  41 , when a predetermined load or force  122  is exerted on the housing  30  of valve  20  (shown as acting on upper housing  34 , but load  122  could also act on lower housing  32 ) on either side of the weakened portion  94 , either directly or indirectly, valve  20  can define a failure mode that depends on the value of force  122 . The most common instance that may create a failure in the housing  30  is the inadvertent contact of a motor vehicle with the fuel dispensing unit  38  that houses pipe  42 . However, a failure in housing  30  may result from any relative movement between portions of the housing  30  above and below weakened portion  94  caused by external forces including frost heave and other environmental conditions. In one failure mode, the force  122  is not sufficient to cause a first portion  124  of the housing  30  to substantially completely separate from a second remainder portion  125  of housing  30  along weakened portion  94  (valve shearing), but is sufficient to cause a crack  126  or other distress in housing  30 , indicated in exaggerated form in  FIGS. 3B and 3C , to emanate from the weakened portion  94  whereby the fluid flow passage  54  is in fluid communication with the expansible chamber  108  (valve cracking). Accordingly, in this failure mode, the structural integrity of housing  30  is compromised to an extent wherein the fuel flowing within passage  54  can escape from housing  30  through the weakened portion  94  and into the expansible chamber  108  under the fuel line pressure. This in turn causes the expansible member  100  to expand outwardly as shown in  FIGS. 3B and 3C , as a result of the pressurized fuel entering chamber  108 . Since the expansible member  100  is sealed to the upper housing  34 , any fuel entering chamber  108  is retained therein, which prevents or reduces fuel from escaping from the valve  20  and thereby reduces the likelihood of environmental spills and the costs associated with the cleanup of such spills. 
     The protruding portion  92  of first link  76  may be disposed in relatively close proximity to the expansible member  100 . Accordingly, when the member  100  expands outwardly, due to pressurized fuel entering expansible chamber  108 , it contacts the protruding portion  92  of first link  76  so that first link  76  uncouples from at least one of the housing  30  and the second link  86 . In the illustrated embodiment, the proximal end  78  of first link  76  disengages from the pin  80  secured to housing  30  as shown in  FIGS. 3B and 3C  so that first link  76  uncouples from housing  30 . In other embodiments, first link  76  may be uncoupled from second link  86  or from both housing  30  and second link  86 . When first link  76  is uncoupled from one or both of the housing  30  and second link  86 , valve element  62  is unlatched from the open position and moves to the closed position as shown in solid line in  FIG. 3C  and in phantom line in  FIG. 4  due to the action of biasing member  72 . When valve element  62  is in the closed position, fuel is prevented from flowing from the fluid inlet  50  to the fluid outlet  52 . Instead, fuel entering inlet  50  after valve element  62  is closed is retained within lower housing  32 , thereby avoiding or reducing the likelihood of fuel spillage externally of housing  30 . 
     When force  122  has a relatively higher value, the weakened portion  94  may define another failure mode (not shown herein) wherein the first portion  124  of housing  30  separates substantially completely from the second portion  125  of housing  30 . In this valve shearing failure mode, the expansible member  100  does not prevent or otherwise inhibit such separation of the first portion  124  of housing  30  from the second portion  125  of the housing  30 . Instead, the force  122  may cause the expansible member  100  to disengage from the housing  30  in a manner that permits the separation of the first and second portions  124 ,  125 . The separation of the valve housings that do not include the expansible member in accordance with the invention, such as member  100 , but are otherwise similar to valve  20 , are illustrated in the foregoing referenced patents. In the event of this valve shearing failure mode, first link  76  would also be uncoupled from one or both of the housing  30  and second link  86 , such that valve element  62  would move to the closed position under the action of biasing member  72  and the valve element  112  of the poppet or check valve  110  would also move to the closed position under the action of biasing member  116 . Accordingly, when the valve element  42  moves to the closed position, fuel may be prevented from flowing through the lower housing  32  and externally of valve  20 . Also, any fuel contained within the pipe  42  may be prevented from backflowing through the upper housing  34  and externally of valve  20 . Accordingly, the likelihood of fuel spillage externally of valve  20  would be prevented or reduced. 
       FIGS. 5 ,  6 A and  6 B, in which like reference numerals refer to like features in  FIGS. 1-4 , illustrate a valve  130  according to another embodiment of the invention. Valve  130  includes a housing, or conduit,  132  comprising an upper housing  134  and a lower housing  32 . Upper housing  134  may be removably secured to lower housing  32  by conventional means such as fasteners  136 . Again, while this embodiment is shown and described as a two-part housing, the invention is not so limited as a one-piece housing may also be utilized. Housing  132  defines a fluid inlet  138 , a fluid outlet  140  and a fluid flow passage  142  ( FIGS. 6A and 6B ) extending between the fluid inlet  138  and the fluid outlet  140 . The fluid flow passage  142  may be suitable for the flow of pressurized fuel therein, such as fuel  24 . 
     Valve  130  may further include an expansible member  144 , in lieu of expansible member  100 , that defines an expansible chamber  145  ( FIG. 6B ) and is disposed in surrounding relationship with a weakened, or frangible, portion  146  formed in upper housing  134  and is sealed to the upper housing  134  at a first location  148  downstream of the weakened portion  146  and at a second location  149  upstream of the weakened portion  146 . The weakened portion  146  may be a groove extending around a perimeter of upper housing  134  and may be generally V-shaped as shown in  FIGS. 6A and 6B . The expansible member  144  may be a sleeve and may have a somewhat different configuration than the expansible member  100 , as shown in  FIGS. 6A and 6B . Expansible member  144  may be made of the same elastomeric materials discussed previously with regard to expansible member  100 . 
     Valve  130  may include a latching mechanism, indicated generally at  149 , which releasably latches the valve element  62 , disposed in the lower housing  32 , in the open position. In the illustrated embodiment, latching mechanism  149  may be a linkage. However, latching mechanism  149  may be other devices suitable for latching valve element  62  in the open position. During normal operation of valve  130 , i.e., not during a failure mode of valve  130 , linkage  149  may be coupled to both valve element  62  and housing  132 . Linkage  149  may include a first link  150  having a first link portion  152  that is pivotally coupled to housing  132 . The pivotal coupling of first link portion  152  to housing  132  may be achieved by a pin  154 , or like member, which extends through first link portion  152  into an embossment  156  secured to upper housing  134 . The first link  150  may further include a second link portion  158  also pivotally coupled to housing  132 . In the illustrated embodiment, pin  154  passes through both of the first and second link portions  152 ,  158  and into embossment  156 . Second link portion  158  includes a first arm  160  pivotally coupled to pin  154 , a second arm  162  coupled to the first arm  160 , and a third arm  164  that is coupled to second arm  162  and also pivotally coupled to the upper housing  132 . Second arm  162  extends generally tangentially relative to upper housing  134  of housing  132  proximate the expansible member  144 . The pivotal coupling of third arm  164  to housing  132  may be achieved by a pin  166 , or like member, which extends through third arm  164  into an embossment  168  secured to upper housing  134 . Pins  154  and  166  may be coaxially disposed so that first and second link portions  152  and  158  pivot together about a centerline axis  170  of pins  154  and  166 , which may be separate pins or can be made as a one piece construction. Moreover, while second link portion  158  is shown and described as an integral member, i.e., the first, second and third arms  160 ,  162 , and  164  are integrally formed, those of ordinary skill in the art will recognize that the arms may be separate and then assembled to form second link portion  158 . 
     As best seen in  FIGS. 6A and 6B , first link portion  152  may include a notch  180  formed therein. Linkage  149  further includes the second link  86  as in valve  20  and discussed previously. Second link  86  may also include a pin  182  extending from second link  86  that is received in the notch  180  of first link portion  152 . A biasing member  184 , which may be a spring coiled about pin  154 , biases the first link portion  152  toward a position wherein pin  182  is engaged in notch  180 . For instance, in  FIGS. 6A and 6B , the spring biases first link portion  152  in the counterclockwise position. In this position, valve element  62  of valve  60 , disposed in lower housing  32  and illustrated and discussed previously with regard to valve  20  (not shown in  FIGS. 5-6B ), is latched in an open position. 
     Since the lower housing  32  of valve  130  is rigidly mounted within sump  41 , when a predetermined force  190  is exerted on the housing  132  of valve  130  (shown as acting on upper housing  134 , but load  190  could also act on lower housing  32 ) on either side of the weakened portion  146  either directly or indirectly, valve  130  can define a failure mode that depends on the value of force  190 . The most common instance that may create a failure in housing  132  is the inadvertent contact of a motor vehicle with the fuel dispensing unit  38  that houses pipe  42 . However, a failure in housing  132  may result from any relative movement between portions of the housing  132  above and below weakened portion  146  caused by external forces such as frost heave or other environmental conditions. In one failure mode, the force  190  is not sufficient to cause the first portion  124  of housing  132  to substantially completely separate from the second remainder portion  125  of the housing  132  along weakened portion  146  (valve shearing), but is sufficient to cause a crack  194  or other distress, indicated in exaggerated form in  FIG. 6B , to emanate from the weakened portion  146  whereby the fluid flow passage  142  is in fluid communication with the expansible chamber  145  (valve cracking). Accordingly, in this failure mode, the structural integrity of housing  30  is compromised to an extent wherein the fuel flowing within passage  142  can escape from housing  132  through the weakened portion  146  and into the expansible chamber  145  under fuel line pressure. This in turn causes the expansible member  144  to expand outwardly as shown in  FIG. 6B , as a result of the pressurized fuel entering chamber  145 . Since the expansible member  144  is sealed with the upper housing  134 , any fuel entering chamber  145  may be retained therein, which may prevent or reduce the likelihood of fuel spillage externally of valve  130 . 
     The second arm  162  of second link portion  158  is disposed in relatively close proximity to the expansible member  144 . Accordingly, when the expansible member  144  expands outwardly, due to pressurized fuel entering expansible chamber  145 , it contacts second arm  162  so that second link portion  158  rotates upwardly relative to the upper housing  134  and about axis  170 . Due to the connection at pin  154 , first link portion  152  rotates downwardly relative to upper housing  134  about axis  170 , thereby disengaging pin  182  from notch  180 . This rotation of first link portion  152  uncouples the first link portion  152  from second link  86 , which is coupled to valve element  62  (shown and discussed previously with regard to valve  20 ; not shown in  FIGS. 5 ,  6 A and  6 B). Accordingly, valve element  62  is unlatched from the open position and moves to a closed position (shown previously with respect to valve  20 ) within the lower housing  32  due to the action of biasing member  72 . When valve element  62  is in the closed position, fuel is prevented from flowing from the fluid inlet  138  to the fluid outlet  140 . Instead, fuel entering inlet  138  after valve element  62  is closed is retained within lower housing  32 . Accordingly, the likelihood of fuel spillage externally of valve  130  may be reduced or prevented. 
     In the illustrated embodiment, valve  130  does not include the poppet or check valve  110 . However, this may be optionally included in other embodiments. If poppet valve  110  is included, the poppet valve  110  may be moved to a closed position, as discussed previously with regard to valve  20  when a relatively larger predetermined load causes the housing  132  to substantially completely separate. The expansible member  144  does not prevent or otherwise inhibit this separation of the housing  132 . Linkage  149  is also uncoupled from valve element  66  in this valve shearing failure mode, so that valve element  62  moves to the closed position under the action of biasing member  72 . The poppet valve may also move to the closed position as discussed previously with respect to valve  20 , if incorporated in valve  130 . 
       FIGS. 7 and 8 , in which like reference numerals refer to like features in  FIGS. 1-6 , illustrate an emergency shutoff valve  200  according to another embodiment of the invention. Valve  200  comprises a housing  210  that includes the lower housing  32  as described for valves  20  and  130  and discussed previously, and an upper housing  212  that may be removably secured to the lower housing  32  by conventional means, such as bolts  214 . The Housing  210  may be a one-piece construction instead of the two-part construction described herein. Housing  210  of valve  200  defines a fluid inlet  220 , a fluid outlet  222  and a fluid flow passage  224  extending between the fluid inlet  220  and the fluid outlet  222  as shown in  FIG. 8 . Fluid flow passage  224  may be suitable for the flow of pressurized fuel therein, such as fuel  24 . 
     As with valves  20  and  130 , the shutoff valve  200  includes a valve member  60  that can be a flapper or butterfly type valve that is movably mounted within the lower housing  32 . Valve member  60  includes the valve element  62  that is movable between an open position and a closed position as illustrated and discussed previously with respect to valve  20 . Valve element  62  may be biased toward a closed position by the biasing element  72  as discussed previously with respect to valve  20 . When valve element  62  is in the closed position, fuel flow between fluid inlet  220  and fluid outlet  222  is prevented. 
     Shutoff valve  200  may include a latching mechanism indicated generally at  229  in  FIG. 7 , which releasably latches valve element  62  in the open position. In the illustrated embodiment, latching mechanism  229  may be a linkage. However, latching mechanism  230  may be other devices suitable for latching valve element  62  in the open position. During normal operation of valve  200 , i.e., not during a failure mode of valve  200 , linkage  229  may be coupled to both the valve element  62  and to housing  210 . Linkage  229  may include a first link  230  and may also include the second link  86 , as in valves  20 ,  130  and discussed previously, which is coupled to valve element  62  in the same manner as discussed previously with respect to valve  20 . First link  230  includes a proximal end coupled to housing  210 . This can be accomplished by a pin  236  that passes through a proximal end of link  230  into an embossment  238  secured to the upper housing  212  of valve  200  as shown in the illustrated embodiment. A distal end of first link  230  may be coupled to second link  86 . This may be accomplished by a pin  240  extending from the proximal end  84  of second link  85  that passes through the distal end of first link  230  as shown in the illustrated embodiment. The first link  230  latches the valve element  62  in an open position when the linkage  229  is coupled to both housing  210  and valve element  66 . 
     Housing  210  may include a weakened, or frangible, portion  242  formed therein that is downstream of the valve element  62 . In the illustrated embodiment, upper housing  212  may include the weakened portion  242  formed therein, which extends circumferentially around a perimeter of the upper housing  212 . The invention, however, is not so limited. The weakened portion  242  may be a groove and may have an inner portion that is generally V-shaped, as shown in  FIG. 8 . The weakened portion  242  defines a predetermined fracture or failure site for various failure modes as subsequently discussed. 
     Valve  200  may further include an annular member  246  that partially circumscribes the upper housing  212  and may be sealed to the upper housing  212  at locations that are upstream and downstream of the weakened portion  242 , which may be accomplished using O-rings  248 , for example. Annular member  246  may be made of a variety of materials including plastics, metals and elastomeric materials. A hollow protruding member  250  may be formed integral with the annular member  246  and extends away from the upper housing  212 . Valve  200  may further include an expansible member  252  that comprises a diaphragm in the illustrated embodiment that is disposed in sealing engagement with the protruding member  250 . An upper portion  253  of first link  230  is disposed proximate the hollow protruding member  250 . Expansible member  252  may be made of an elastomeric material such as the materials discussed previously with regard to the expansible member  100  of valve  20 . The expansible member may also be inelastic but be formable so as to operate as a rolling diaphragm. Expansible member  252  defines at least a portion of an expansible chamber  254  that is disposed externally of housing  210 , and more particularly is disposed externally of the upper housing  212 . The expansible chamber  254  includes at least the space within the hollow protruding member  250  between the expansible member  252  and the upper housing  212 . Depending upon the properties of the material used to make the annular member  246 , the expansible chamber  254  may also include the space between the annular member  246  and the upper housing  212 , including the space between the weakened portion  242  and annular member  246 . 
     Since the lower housing  32  of valve  200  is rigidly mounted with sump  41 , when a predetermined force  270  is exerted on the housing  210  of valve  200  on either side of the weakened portion  242 , either directly or indirectly, valve  200  may define a failure mode that depends on the value of force  270 . In one failure mode, the force  270  is not sufficient to cause a first portion  124  of housing  210  to substantially completely separate from a second remainder portion  125  of housing  210  along weakened portion  242  (valve shearing), but is sufficient to cause a crack  274  or other distress emanating from the weakened portion  242 , indicated in exaggerated form in  FIG. 8 . In this failure mode, the fluid flow passage  224  is in fluid communication with the expansible chamber  254 . Accordingly, in this failure mode, the structural integrity of housing  210  is compromised to an extent wherein the fuel flowing within passage  224  can escape from housing  210  through the weakened portion  242  and into the expansible chamber  254  under fuel line pressure. This in turn causes the expansible member  252  to expand outwardly as shown in phantom line in  FIG. 8 , as a result of the pressurized fuel entering chamber  254 . Since the expansible member  252  is sealed to the upper housing  212 , fuel entering chamber  254  is retained therein, which may prevent or reduce fuel from escaping from the upper housing  212  externally of valve  200 . 
     The first link  230  of linkage  229  is disposed in relatively close proximity to the expansible member  252 . Accordingly, when the expansible member  252  expands outwardly under fluid pressure it contacts first link  230  so that first link  230  moves outwardly as shown in phantom line in  FIG. 8  and is uncoupled from housing  210  and second link  86 . In other embodiments, it is possible for first link  230  to become uncoupled from only one of the housing  210  and second link  86 . When first link  230  is uncoupled from one or both of the housing  210  and second link  86 , valve element  62  may be unlatched from the open position and moves to the closed position, as discussed and illustrated previously with respect to valve  20 . When valve element  62  is in the closed position, fuel is prevented from flowing from the fluid inlet  220  to the fluid outlet  222 . Instead, fuel entering inlet  220  after valve element  62  is closed may be retained within lower housing  32 , thereby preventing or reducing the likelihood of spillage of fuel externally of housing  210 . 
     In the illustrated embodiment, valve  200  does not include the poppet or check valve  110  shown and discussed previously with regard to valve  20 . However, valve  110  may be optionally included in other embodiments. If poppet valve  110  is included, the poppet valve  110  may be moved to a closed position, as discussed previously with regard to valve  20  when the load  270  has a relatively larger value, than that existing in the first failure mode, causing the first portion  124  of housing  210  to substantially completely separate from the second portion  125  of housing  210 . The annular member  246 , protruding member  250  and expansible member  252  do not significantly prevent such separation of the housing  210 , i.e., they are not made of materials that would prevent such separation. In this event, the poppet valve  110  would move to the closed position as discussed previously, preventing or reducing the backflow of fuel from the dispensing unit through valve  110 , thereby preventing or reducing the likelihood of spillage external of valve  200 . Additionally, the first link  230  would be uncoupled from one or both of housing  210  and second link  86  in this valve shearing failure mode as well, so that valve element  62  would move to the closed position and stop the flow of fuel through valve  200 . 
     The various embodiments of the emergency shutoff valve as disclosed herein generally have a housing with a weakened portion and an expansible member defining at least a portion of an expansible chamber in surrounding relationship to the weakened portion. The expansible member may be operatively coupled to a valve member in the shutoff valve to close the flow of fuel through the valve when the expansible member is actuated. The valves disclosed herein provide certain advantages over existing shear valves. In particular, for failure modes that crack the valve without substantially completely shearing the valve, the valve according to embodiments of the invention prevent or reduce the likelihood of fuel spillage that would otherwise occur with existing shutoff valves. In addition, this benefit is attained by using the fuel line pressure itself as the motive force for closing off the valve in such a valve cracking failure mode. Thus, no additional energy or energy consuming components must be supplied to the shutoff valve to actuate the valve to a closed position. The shutoff valves according to the invention then provide additional benefits relative to conventional valves in a low cost manner that utilizes the pressure of the fueling system to achieve these benefits. 
     While the foregoing description has set forth various embodiments of the present invention in particular detail, it must be understood that numerous modifications, substitutions and changes can be undertaken without departing from the true spirit and scope of the present invention as defined by the ensuing claims. The invention is therefore not limited to specific embodiments as described, but is only limited as defined by the following claims.