Patent Abstract:
In a valve used for dispensing flowable product from a pressurized container A cup is snapped onto the button at the base of the valve stem so that the upper rim of the cup engages the resilient sealing grommet that surrounds the main portion of the stem. The upper rim of the cup provides a moderately sharp sealing edge so that the pressure against the surface of the resilient grommet is enhanced. This creates a more effective seal than does the relatively broad surface to surface engagement between button and grommet in a standard valve.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to ensuring that a valve is sealed in a pressurized dispensing container when the valve is in its closed state. 
         [0002]    The problem of obtaining a fully effective seal in the closed state of the valve arises in connection with dispensing products that have grit or particles. Peanut butter is one such product. 
         [0003]    It has been found that a number of products cannot be dispensed with these pressurized containers because there is some minimal leakage or, at least inadequate sealing. The result is that the product deteriorates in some way. 
         [0004]    For example, in peanut butter the oil separates out from the rest of the product and when dispensed, the oil comes out first, separate from the rest of the product. This is entirely unsatisfactory to the end user. 
         [0005]    The sealing elements in the valve are the button on the base of the valve stem and the resilient grommet that surrounds the valve stem. It is believed that what happens is that particles lodge between the button and the grommet providing enough communication across the seal to create some pressure differential across the product. In peanut butter, this causes oil separation when the container is not being used. Regardless of the exact mechanism, this deterioration of product has been observed. 
         [0006]    Accordingly, it is a major object of this invention to provide a structure that assures a complete and effective seal when the valve is in its closed state so that there is no communication across the seal. This will assure that the product is under constant pressure throughout the mass of the product while it is on the shelf. 
         [0007]    It is a related purpose of this invention to achieve the main object in an inexpensive fashion with a design which does not modify or compromise the dispensing operation of the container. 
         [0008]    It is a further related purpose of this invention to achieve the above objects in a design which involves use of one of the present valve designs so as to minimize the cost of adopting the invention. 
       BRIEF DESCRIPTION 
       [0009]    In brief, a device of this invention employs a cup shaped device which is press fit or snapped onto the valve stem button so that the walls of the sealing cup extend above the button. When the valve is sealed, the upper rim of the walls of the sealing cup press into the lower base of the grommet providing a seal which is not compromised by the grit or particles in the product. 
         [0010]    To enhance and assure the effective sealing result, the preferred molded plastic sealing cup has a chamfered wall at its upper rim to provide a narrow sealing edge. The resultant high pressure level assures an effective seal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a side view, in partial section, of the valve  10  of this invention.  FIG. 1  shows the arrangement between the valve stem  12  and grommet  14  and also shows the sealing cup  16  fitted onto the button  18  at the base of the stem  12 .  FIG. 1  shows the valve  10  in a closed state. 
           [0012]      FIG. 2  is a sectional view, on a larger scale, more clearly showing the engagement between the sealing edge  38  which is at the top rim  20  of the sidewall  22  of the sealing cup  16  and the base surface  24  of the grommet  14 .  FIG. 2 , shows the closed state of the valve. In that state, the button  18  is spaced by a space  42  of a few mils (five mils in one embodiment) from the base surface  24  of the grommet  14 . (Note: one mil equals 0.001 inches). This assures that there will be no engagement between button  18  and grommet surface  24  that would limit full force engagement of the sealing edge  38  with the grommet surface  24 . 
           [0013]      FIG. 3  is a simplified sectional view of the sealing cup  16  showing the annular recess  36  on the inner surface of the sidewall  22  and the annular sealing edge  38  on the rim  20 . To simplify presentation,  FIG. 3  omits the horizontal lines representing the upper edges of the sidewall  22 . 
           [0014]      FIG. 4  is a view in partial section of one presently preferred embodiment having the sealing cup  16 A mounted on a thicker than usual button  18 A.  FIG. 4  is adapted for use as a tilt valve. 
           [0015]      FIG. 5  is a view in partial section showing an embodiment employing the arrangement of sealing cup  16 A and button  18 A shown in  FIG. 3 .  FIG. 5  shows the use of a resilient tube  44  to provide a restoring force returning the valve to its closed state when dispensing pressure is removed from the nozzle  46 . The  FIG. 5  design has been designed for dispensing peanut butter. 
           [0016]      FIG. 6  is a view in partial section of an embodiment similar to that of  FIG. 5  except that a spring  50  is used instead of the resilient tube  44  to provide a restoring force returning the valve to its closed state. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]      FIGS. 1 through 3  illustrate a first embodiment. A pressurized dispensing container (not shown) has a top center opening through which the valve  10  extends. The stem  12  of the valve is partially threaded so as to engage the threaded inner surface of a nozzle (not shown). A resilient grommet  14  extends around the lower portion of the valve stem  12  and is held between the button  18  at the base of the valve stem and a downwardly facing ledge  26  on the valve stem  12 . In the closed state the grommet  14  seals the valve stem openings  28 . The mounting cup  15  holds the valve on the container (not shown). 
         [0018]    When the nozzle (not shown) forces the valve stem  12  to move, by either tilting or by vertical movement, one or more of the valve stem openings  28  are exposed to the product held under pressure within the interior of the container. The product under pressure will then be forced through one or more of the openings  28  to a central axial passageway of the valve stem to exit from an opening at the top of the valve stem into the nozzle (not shown) to be dispensed at the upper end of the nozzle. 
         [0019]    The operation of these valves in pressurized dispensing containers is well known and is described in greater detail in U.S. Pat. No. 7,222,758; No. 6,874,663. and No. 5,785,301. In the closed state, the prior art devices do not have the sealing cup  16  and effect a sealing engagement primarily by engagement between the top surface of the button  18  and the base surface  24  of the grommet  14 . This face to face engagement is maintained by the pressure of the product within the container on the button  18  and may also be maintained by a restoring force exerted by engagement of the boot  30  of the grommet  14  against the ledge  26  on the stem  12 . As shown in  FIGS. 5  and  6 , a spring  50  or resilient tube  44  may be used to provide the restoring force in lieu of or in addition to the boot  30 . 
         [0020]    In particular, where the grommet is soft, the restoring force of the boot  30  might have to be supplemented with a spring or other resilient member. 
         [0021]    This surface engagement between button  18  and grommet  14  is quite effective to provide a seal in the closed state for a smooth flowable product. It does not work well for products containing particles, for example, peanut butter. It is believed that what happens is that granules of product are lodged between the engaging surfaces of the button  18  and the grommet  14 . It is believed that these particles cause enough of a break in the sealing surface so that a pressure gradient is established across the sealing surface between the ambient pressure in the valve stem passageway and the product pressure in the interior of the container. This pressure gradient results in the product adjacent to the seal between grommet  14  and button  18  having a lower pressure than the pressure of the product within the dispensing container. The higher pressure is created by the pressurized gas in the pressure producing chamber. It is believed that this results in the peanut butter product having the oil and the denser product separate out when standing on the shelf. The result is that when the user actuates the valve, the product dispensed is not well mixed and initially the oil component is dispensed by itself. This is completely unsatisfactory to the user. The particles that cause this pressure gradient generally do not create sufficient passageway to leak product in closed state. 
         [0022]    Applicant believes that the above analysis is the explanation of what occurs in the use of prior art designs. But there may well be a somewhat different explanation or, more likely, a supplementary explanation. 
         [0023]    But, what has been found is that the use of a sealing cup  16  to effect a high pressure engagement with the grommet  14  provides an effective seal so that this product separation does not occur. Tests have been made with peanut butter using the device of this invention and the results have been satisfactory in that the oil did not separate out. 
         [0024]    As shown in  FIGS. 1-3 , the upper rim  20  of the sidewall  22  is chamfered to provide an annular sealing edge  38  that is a blunt knife like edge. This edge  38  transmits the full pressure from the pressurized product along a narrow annular zone so as to provide a high pressure in psi in the closed state at the lower surface  24  of the grommet  14 . This assures that the resilient grommet  14  will be adequately deformed at the sealing zone created by the sealing edge  38 . Because of the force of the engagement over the small surface area involved, product particles do not compromise the effective sealing. The engagement between sealing cup  16  and button  18  is a press fit supplemented by a ridge  34  and recess  36  engagement. 
         [0025]    A presently preferred embodiment for use with the dispensing of peanut butter is shown in  FIG. 4 .  FIG. 4  shows only the stem  12  with its button  18 A and the sealing cup  16 A. As shown therein, the stem  12  of the valve terminates in a button  18 A. The sealing cup  16 A has an annular sidewall  22  which engages the button  18 . This engagement may be press fit or by snap fit or by both. As shown in  FIG. 4 , the preferred button includes an annular ridge  34 A which snaps into a mating recess  36 A in the sidewall  22  of the sealing cup  16 . 
         [0026]    The  FIG. 4  embodiment shows an arrangement in which the thickness of the button  18 A is greater than is usually the case. This thickness is chosen for a tilt valve application so as to assure that the force of tilting does not cause the sealing cup  16 A to disengage. In the  FIG. 4  embodiment, the base  40 A of the sealing cup  16 A extends radially beyond the sidewall  22 A in order to provide a greater force from product under pressure to achieve and maintain an effective seal in the closed state. 
         [0027]    In a vertically movable valve application, a press fit between a regular size button and a sealing cup, together with a ridge  34  and groove  36  engagement, as shown in  FIGS. 1 through 3 , would normally be adequate to assure retention of the sealing cup on the button. 
         [0028]    The ridge  34  can be on either the inner surface of the annular sidewall  22  or on the annular side surface of the button  18 . In the  FIG. 4  embodiment, a ridge  34 A and groove  36 A arrangement is used to reinforce the retention engagement effected by the thick button  18 R. 
         [0029]    In one preferred embodiment having the geometry shown in  FIG. 2 , the following dimensions were found to be effective: A nylon sealing cup  16  has a 35 mil (0.035 inch) thick annular sidewall  22 , a 161 mil outer wall surface diameter, a 40 mil thick base and a 30 degree internal angle for the chamfer that creates the sealing edge  38 . The edge  38  is about three mils thick. A 369 mil ID for the sealing cup  16  engages a 370 mil diameter button  18 . The ridge  34  and groove  36  have a five mil maximum interference created by a 23 mil radius of curvature. In the closed state, the sealing edge  38  depresses the grommet surface  24  by about 10 to 20 mils. That would be a function of grommet durometer. 
         [0030]    In another preferred embodiment having the geometry shown in  FIG. 4 , the following dimensions were found to be effective: A 369 mil ID of the sealing cup  16  engages a 370 mil diameter button. The button  18 A is made 125 mils thick and has a ridge  34 A that engages a groove  36 A with a maximum of three mil interference created by a radius of curvature of 60 mils. 
         [0031]      FIG. 5  illustrates an application of the invention to a design which in this particular case is for peanut butter. In the  FIG. 5  design, an annular resilient tube  44  is used in conjunction with the nozzle  46  having an annular hood  48 .  FIG. 5  is in the open state. 
         [0032]    When the product is manufactured, the nozzle  46  is screwed all the way down so that the hood  48  abuts against the mounting cup  15 . In this condition, the resilient tube  44  is in compression and exerts a upward force on the nozzle  46  that pulls the stem  12  in an upward direction thereby assuring that the edge  38  of the sealing cup  16 A forcibly engages the base surface  24  of the grommet  14 . 
         [0033]    In use, the user unscrews the nozzle  46  to a point where the rubber tube  44  is held in position without exerting significant force. At that point, the nozzle  46  can be tilted and product dispensed. When the user finishes applying the peanut butter, the user screws the nozzle  46  to close and seal the container. But as a practical matter, many users will not screw the nozzle  44  all the way down to the point where the hood  48  will engage the upper surface of the mounting cup  15 . In some cases, the restoring force provided by the boot  30  of the grommet  14  will not exert enough force to make sure that the sealing edge  38  of the sealing cup  16 A will adequately engage the lower surface  24  of the grommet  14 . The compression of the resilient tube  44 , even if it is not fully compressed, as when initially shipped, will provide sufficient restoring force to assure engagement of the sealing edge  38  and grommet surface  24 . 
         [0034]    As shown in  FIG. 6 , a cylindrical spring  50  in compression can be employed in lieu of the resilient tube  44  so as to provide a closing force. This closing force provided by tube  44  or spring  50  also serves to stabilize the valve stem. 
         [0035]    Preferred embodiments of the invention have been disclosed. However, it would be well within the understanding of one skilled in the art that certain variations can be made and stay within the scope of the teachings of this invention. 
         [0036]    For example, the narrow sealing edge  38  could be created along the inner wall of the sealing cup  16  rather than the outer wall as shown. Indeed, this sealing edge  38  could be created at some intermediate position between the inner wall and outer wall of the rim  20  of the sealing cup  16 . 
         [0037]    Another example is that the sealing cup  16  could be created integrally with the button  18 . Such an approach will create molding problems and for that reason is not preferred. 
         [0038]    As shown in  FIG. 4 , in one preferred embodiment, the thickness of the button  18 A is greater than is usually the case in order to assure that in a tilt valve embodiment the sealing cup  16  will not rack on the button  18 . Where a vertical valve operation is involved, then as shown in  FIGS. 1 through 3 , the button  18  may well be less thick than shown in  FIG. 4 . In such a case, an interference fit, without the annular ridge  34  and recess  36  could be sufficient in some applications to maintain the cup on the button. Experimentation in each application will be required to determine the best fitting relationship between the sealing cup  16  and button  18  and whether or not the ridge  34  and recess  36  engagement is required or useful. 
         [0039]    The sealing cup  16  is preferably made of plastic. Nylon has been found to be useful and a preferred material. The sidewall of the sealing cup  16  is approximately 35 mils (0.035 inches) and the width of the sealing edge  38  is approximately three mils. However, it might be possible for a metal cup having a sidewall of 5 mils to be effectively used in certain situations. In such an embodiment the rim  20  becomes the edge  38 . Such an embodiment is not presently preferred. 
         [0040]    It is believed that it is desirable and preferable to avoid a sealing edge  38  so sharp as to cut the surface  24  of the resilient grommet  14 . 
         [0041]    As known in the art, the composition of the grommet  14  and of the restoring boot  30  and the composition of any restoring tube  44  or spring  50  will depend on an appropriate combination thereof and trade off with the range of product pressures from full to dispensed.

Technology Classification (CPC): 1