Abstract:
A valve assembly for use in fluid-containing vessels for controlling the filling thereof comprises a main body having an inlet opening ( 20 ) and an outlet opening or openings ( 22 ) into the vessel and defining a fluid flow path therebetween; a movable valve member ( 40 ) movable from an open position to a closed position against a valve seat ( 34 ) defined in the fluid flow path; and control means including a float assembly comprising a float ( 54 ) mounted on a pivotably mounted float arm ( 52 ), and a retaining member ( 64 ) mounted on the body for pivotal movement and driven by the float arm, and having a retaining position at which the valve member ( 40 ) is maintained in an open position and out of which the retaining member is driven as the float arm ( 52 ) pivots from a lower position to a predetermined angle associated with a predetermined fluid level with an actuating cam surface on the float arm acting on the valve member ( 40 ) to move this to an open position as the float arm pivots towards its lower position.

Description:
BACKGROUND OF INVENTION  
       [0001]     The invention relates to valve assemblies for fluid-containing vessels, such as pressurized vessels. More particularly, the invention relates to valve assemblies for controlling the filling of such pressurized fluid vessels.  
         [0002]     Various valve assemblies constructed to avoid overfilling of pressurized fluid vessels are known. In U.S. Pat. No. 5,282,496 there is disclosed a two-way valve for filling and draining a gas cylinder. The valve assembly includes a float assembly for control of the opening and closing of the valve as a function of the fluid level in the tank so that the valve can be closed when the fluid level corresponds to the predetermined safe capacity of the vessel.  
         [0003]     U.S. Pat. No. 6,076,546 discloses an overflow protection valve assembly in which the valve plunger is separated from the fluid flow to prevent premature closing due to the pressure on the valve plunger.  
         [0004]     Applicant&#39;s U.S. Pat. No. 6,293,302 discloses a simple valve assembly having a float arm and movable valve body supported on a valve stem disposed to move in and out of a flow path under the action of an actuating member driven by a float which acts directly on a lower end of a valve stem. The valve assembly finds particular applicability for use in liquefied petroleum tanks, such as propane tanks, where it is important from a safety perspective that the tank is not overfilled.  
         [0005]     The present invention seeks to provide a further improved valve assembly which provides positive, reliable closure and yet is of simple overall construction.  
       SUMMARY OF THE INVENTION  
       [0006]     In a first aspect the invention resides in a valve assembly for use in fluid-containing vessels for controlling the filling thereof, comprising: a main body having an inlet opening and an outlet opening and defining a fluid flow path therebetween; a movable valve member movable from an open position to a closed position against a valve seat defined in the fluid flow path; valve control means comprising: a float mounted on a pivotably mounted float arm; a retaining member mounted for pivotal movement and driven by the float arm, and having a retaining position at which the valve member is maintained in an open position and out of which the retaining member is driven as the float arm pivots from a lower position to a predetermined angle associated with a predetermined fluid level, at which point the retaining member releases the valve member; and actuating cam means acting on the valve member to move this to an open position as the float arm pivots towards its lower position.  
         [0007]     The use of the retaining member driven by the float arm in this manner ensures that relatively small movements of the float arm in say a partly filled container do not have the effect of opening and closing the valve, but rather this opens only when the retaining member is driven out of the retaining position when the vessel is filled. This makes the valve less susceptible to rapid opening/closing as might occur if the tank were shaken from side to side.  
         [0008]     In the preferred embodiment the actuating cam means is formed on a surface of the float arm. The float arm is formed with a forward drive surface which abuts said retaining member as the float arm approaches its lower position, whereby the retaining member is driven by the float arm to its retaining position. The float arm is formed with a rear drive surface which abuts the said retaining member, driving it out of the retaining position as said predetermined angle is reached on rising of the float arm.  
         [0009]     The retaining member is preferably provided with biasing means which urge it towards the retaining position. It may also be provided with stop means which prevent rotation beyond said retaining position. The retaining member is conveniently disposed to sit in a cut-out in an end region defined of the float arm, said drive surfaces defining at least a portion of the edge of the cut-out, being pivotably mounted for rotation about an axis coincident with the float arm.  
         [0010]     The valve member is supported on a valve stem, and end of which is exposed and which is acted on by said actuating cam means and retaining member. The retaining member may be provided with a lip against which the valve stem bears in the retaining position. The valve means is preferably biased to said closed position by resilient means, such as a conical spring.  
         [0011]     In an alternative arrangement the actuating cam means comprises a cam surface on the retaining member. 
     
    
     BRIEF INTRODUCTION TO THE DRAWINGS  
       [0012]     An embodiment of the invention is now described, by way of example only, with reference to the following drawings in which:  
         [0013]      FIG. 1  is a schematic part-sectional view of the valve assembly in accordance with an embodiment of the invention, in an open position;  
         [0014]      FIG. 1A  shows an enlarged detail of an actuator end of a float arm of  FIG. 1 ;  
         [0015]      FIG. 1B  shows a further enlarged detail of the view of  FIG. 1A  showing a retaining member against a lower end of a valve stem;  
         [0016]      FIG. 2  is an exploded view of an end cap and float arm assembly;  
         [0017]      FIG. 3  shows the valve assembly of  FIG. 1  in a partly full condition of a fluid-containing vessel;  
         [0018]      FIG. 3A  is an enlarged detail of the actuator cam and retaining member of  FIG. 3 ;  
         [0019]      FIG. 4  shows the valve assembly in a further filled condition;  
         [0020]      FIG. 4A  is an enlarged detail of the actuator cam and retaining member of  FIG. 4 ;  
         [0021]      FIG. 5  shows the valve assembly in a full condition with the valve closed;  
         [0022]      FIG. 5A  is an enlarged detail of the actuator cam and retaining member of  FIG. 5 ;  
         [0023]      FIG. 5B  is an enlarged detail corresponding to  FIG. 5A  but where the spring is shown;  
         [0024]      FIG. 6  shows the valve assembly after partial emptying of the vessel with the valve in a partly open condition;  
         [0025]      FIG. 6A  is an enlarged detail of the actuating cam and retaining member of  FIG. 6 ;  
         [0026]      FIG. 7  shows the valve assembly in a further emptied condition of the vessel with the valve fully open;  
         [0027]      FIG. 7A  is an enlarged detail of the actuator cam and retaining member of  FIG. 7 ; and  
         [0028]      FIG. 8  shows the valve assembly fitted in a vessel which requires filling.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0029]     The invention is directed to a valve assembly for use in a pressurized fluid vessel. The valve assembly allows filling of pressurized fluid into the vessel and unloading of the fluid from the vessel through essentially the same fluid flow path, controlled by a valve plunger. Preferred embodiments of the invention are described in the context of a tank for containing liquefied petroleum gas such as propane, such being commonly used in the home, for example for cooking appliances, and for barbecues and grills and the like. It should be understood that the principles of the invention are also applicable to other pressurized vessel environments in which control of the filling level is desired or required.  
         [0030]     Referring to  FIG. 8 , a valve assembly  2  is shown installed in a pressurized fluid vessel, such as a propane tank  4 . The propane tank  4  includes an opening  6  to which an external valve  8  is secured. The external valve  8  has a port  10  through which pressurized fluid, such as propane, can be supplied to the vessel and through which the fluid can be dispensed for fuelling an appliance (not shown).  
         [0031]     Opening and closing of the port can be controlled manually by turning a handle  12 , which controls a shut-off valve assembly, not shown but well-known in the art. The external valve  8  can provide a safety valve port  14  for the release of pressurized fluid at a predetermined pressure level, which may be exceeded, for example, if the vessel  4  is overheated.  
         [0032]     The external valve  8  can mount to the vessel  4  by a threaded engagement with the opening  6 . The external valve  8  can also provide an interior threaded connection for securing to an upper threaded stem of the valve assembly  2 . In use, during filling pressurized fluid passes through an upper port in the valve assembly  2  and flows through lower ports out of the valve assembly  2  and into the vessel  4  interior.  
         [0033]     Turning to  FIG. 1 , the valve assembly  2  comprises a main housing having upper and lower housing parts  24 ,  26  respectively. The upper housing part  24  defines the upper threaded stem  27  and defines the upper port  20 . A lower portion defines a male thread  32 .  
         [0034]     The lower housing part  26  has an elongate form which defines an internal cylindrical opening which includes a frustoconical surface which forms a valve seat  34  communicating with a series of radial ports  22 . An upper rim of the lower housing part  26  is internally provided with a female thread  36  whereby upper and lower housing parts can be tightly connected by a screw fit. An axial bore  37  is provided in the lower region of the lower housing part  26 .  
         [0035]     Disposed within the cylindrical interior cavity of the lower housing part  26  is an insert  38  which has the shape of an inverted cup and which functions as a flow diverter. Its exterior is provided with a number of ribs which serve to space the insert  38  from the interior surface of a main internal cavity of the housing part  26  and defining fluid flow paths therebetween.  
         [0036]     Disposed within the open upturned mouth of the flow diverter  38  is a movable valve member  40  which is supported on the end of a valve stem  42  which extends through the lower axial bore  37 . A conical spring  44  is arranged between the interior underside of the flow diverter  38  and an upper surface of the valve member  40 , so as to impart a downward force against the valve member  40 .  
         [0037]     At the base of the lower housing part  26  is an end cap  46  which supports a float assembly which constitutes a control means for controlling the opening and closing of the valve. As best seen in  FIG. 2  the end cap  46  has a cup-like form with a pair of parallel depending supports  48  formed with aligned openings  50 . The supports  48  carry a float arm  52  which is provided with a float  54  secured to the arm by a stem having a threaded end to which a nut  56  is fitted. More particularly, the proximal end of the float arm  52  has an opening  58 , with a pin  60  extending through the openings  50  and  58  with a split ring or “e-ring”  62  fitted to its free end to secure the arm  52 . This proximal end of the arm  52  has a longitudinally-extending extension  53  which constitutes a stop for the arm  52  when it lies in the lowermost position of  FIG. 1 , the extension  53  abutting beneath the underside of the end cap  46 . Adjacent the stop  53  on the surface facing away from the float is a curved region  55  which meets an inclined surface  57  which constitutes a cam surface, best seen in  FIGS. 1A and 1B .  
         [0038]     Also disposed at the proximal end of the float arm  52  is a retaining member  64  which has the form of a part-circular disc supported a collar  66 , subtending an angle of about 140° between opposite edges. The retaining member  64  sits in a cut-out region at the proximal end of the arm  52 , with pin  60  extending through an opening in a collar  66  of the retaining member  64 , and has an outer curved surface  70 , a forward edge constituting a forward abutment surface  72  and a rear edge rear abutment surface  74 . A pin-like stop  76  limits rotation of the retaining member  64 , abutting one of the supports  48  in the downward most position of the float arm. The retaining member  64  is driven predominantly by forward and rear abutment surfaces  78  and  80  respectively on the float arm  52  adjacent and defining the cut-out region.  
         [0039]     It may also be arranged that a spring such as leg spring acts on the retaining member  64 , for example disposed between the stop  76  and an underside of the end cap, in order to impart a clockwise biasing force on the retaining member. This is omitted from the drawings for reasons of clarity, with the exception of  FIG. 5B  which shows the spring indicated  77 .  
         [0040]     The interaction of the retaining member  64  with the adjacent parts of the proximal end of the float arm  52  controls the opening and closing movement of the valve member  40  in a manner as now described with reference to a tank filling operation, and with reference to  FIGS. 1 and 3  to  6 .  
         [0041]      FIG. 1  shows the valve assembly in a condition in which the liquid level in the vessel is beneath the bottom of the float valve  54 . In this condition the float arm  52  hangs vertically downward, with its stop  53  abutting the underside of the cap  46 , with retaining member  64  driven to a forwardmost (clockwise, as viewed in the Figures) position in which the outer curved surface  70  of the retaining member lying beneath and supporting the lower end of the valve stem  42 , ensuring that this is held upwardly. The valve member  40  is spaced from the valve seat  34 , whereby the valve is in an open condition. The spring  77  serves to hold the retaining member in this forwardmost position. As can be seen in  FIG. 1B  the outer curved surface  70  of the follower  64  may have at its forward end a small protrusion  82  which also helps to stably support the end of the valve stem  42  providing a broader platform for the stem end, although it should be noted that this protrusion is not essential. It will also be noted that the curved surface  70  of the retaining member  64  is shown in  FIG. 1B  to lie slightly higher than the curved surface  55  of the arm  52 . This is not essential, and both surfaces might be coincident.  
         [0042]     In this empty or part-empty condition if a source of pressurized fluid is fitted to the external valve  8  the fluid will flow down through the upper port  20 , around the diverter  38  through the valve clearance and out through the ports  22  into the vessel interior. As the fluid level rises to a sufficient degree to lift the float  54  the arm  52  is caused to rotate in an anti-clockwise sense, as illustrated in  FIG. 3 . The surface  70  of the retaining member  64  remains under the end of the valve stem  42  supporting this in the uppermost position, any frictional force in a clockwise direction being resisted by the frictional force between the stem end and surface  70 , and by the protrusion  82  and/or leg spring. This situation remains on continued filling until the position shown in  FIGS. 4 and 4 A is reached, at which point the drive surface  80  on the float arm  52  abuts the forward abutment surface  72  causing the retaining member  64  to rotate in the anti-clockwise sense.  FIGS. 4 and 4 A show the valve still closed (just), but in  FIGS. 5 and 5 A the surface  70  (and protrusion  82 ) has just cleared the valve stem  42  whereby this can snap down under the influence of the weight of the valve member and the spring  44  which acts on the valve member  40 . The valve member is thereby forced down rapidly against the valve seat  34 , closing the valve and preventing overfilling of the tank.  
         [0043]     Dispensing of pressurized fluid from the vessel is achieved by opening the external valve  8 , the pressure inside the tank being higher than external pressure, and the valve member  40  being pushed up by this pressure difference so that the valve is open for dispensing.  
         [0044]     As the fluid level in the vessel decreases the float and float arm  52  falls.  FIGS. 6 and 6 A show the valve assembly as the float arm  52  has fallen abut 30° from the  FIG. 5  position at which position the cam surface  53  has just engaged beneath the end of the valve stem  42  such that continued downward movement of the float arm  52  causes the cam surface  53  to force the valve stem  42  upwardly. (It will be appreciated however that with suitable adaptation the precise angle at which this engagement occurs can be varied). It is also arranged that at the position where the cam surface  53  engages the valve stem  42 , the forward abutment surface  78  of the float arm  52  abuts the surface  74  of the retaining member  64  driving this in a clockwise sense.  FIGS. 7 and 7 A illustrate the position at which the valve stem  42  is almost fully depressed upwardly. The retaining member  64  has been driven by the abutment surface  78  clockwise, and its forwardmost end is just starting to move beneath the valve stem  42 .  
         [0045]     On continued falling of the fluid level the float  54  moves to its lowermost position with the arm  52  hanging vertically down, as illustrated back in  FIGS. 1, 1A  and  1 B, with the retaining member  64  stably supporting the valve stem  42  and thereby maintaining the valve fully open.  
         [0046]     In a further variation, the cam surface may instead be formed on the forward edge of the retaining member and such that the end of the float arm never engages the end of the valve stem, but rather serves only to drive the retaining member in the clockwise and anticlockwise directions, on emptying and filling.