Abstract:
An axially actuated valve for use in a pressurized container is controlled by a user to dispense the amount of product desired. The valve stem is moved in an up and down direction so that when dispensing, the user can control the amount of the valve openings that are in communication with the material to be dispensed. A resilient sealing grommet provides an interference fit around the lower part of the valve stem from the button up to the top of the valve stem openings. This interference fit effectively closes off the uncovered portion of the valve openings thereby permitting user control of the dispensing rate. The stem has openings partially tapered in the form of an inverted truncated pyramid to further facilitate user control of the dispensing of product.

Description:
REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of Ser. No. 11/334,716 filed Jan. 18, 2006, now abandoned, which in turn is a continuation-in-part of Ser. No. 10/882,625 filed Jun. 30, 2004, now abandoned, which in turn is a continuation of Ser. No. 10/816,969 filed Apr. 2, 2004, now abandoned, which in turn is a continuation of Ser. No. 10/285,238 filed Oct. 31, 2002, now abandoned; the entire disclosures of which are hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   This invention relates to a valve design for use in dispensing product from a pressurized container and more particularly to a valve whose design provides user control over the dispensing rate. This is particularly valuable where pressure in the container is developed from a gas, such as pressurized air or pressurized nitrogen, in which the pressure decreases as product is dispensed. 
   Applicant&#39;s U.S. Pat. No. 5,785,301 and U.S. Pat. No. 6,425,503 and U.S. Pat. No. 6,340,103 are representative of prior art valve designs for use in hand held pressurized containers. 
   The pressure in most of these barrier containers is maintained as product is dispensed by virtue of having the pressure developed through a hydrocarbon type of gas in which a liquid reserve is contained in the pressured gas chamber. As product is dispensed and the pressured gas chamber increases in volume, the liquid will evaporate to maintain a fairly constant pressure. 
   It is known to use pressurized gas such as pressurized nitrogen. In those cases, as product is dispensed and the gas pressure chamber increases in volume, the pressure therein drops. This drop in pressure reduces the rate at which product is dispensed and is inconvenient for the user. 
   Accordingly, pressurized dispensing containers employing pressurized air or nitrogen are not generally used. 
   However, the use of a hydrocarbon causes environmental concerns. Hundreds of millions of these containers are used. When these containers are disposed, they carry the hydrocarbon with which they are initially charged. Eventually this hydrocarbon is released into the environment. 
   There is great concern to provide a practical and useable pressurized dispensing container in which the pressure is created by a pressurized nitrogen or pressurized air or some other more environmentally acceptable pressurized gas. 
   It is a major purpose of this invention to provide a pressurized dispensing container adapted to use pressurized nitrogen or gas that is acceptable to the user. 
   It is a related purpose of this invention to provide such a container in which the user can maintain a substantially consistent dispensing rate of product throughout the use of the container. 
   It is a related object of this invention to obtain this consistent dispensing rate in a design which maintains the cost of the valve and the discharge mechanism at a level that will be cost effective for the user. 
   It is a further purpose of this invention that this ability to maintain a substantially constant discharge rate be easily and readily controllable by the user. 
   It is another purpose of this invention to provide a valve design which is particularly adapted to be used in a vertical fashion; that is, used through axial movement of the valve element. 
   BRIEF DESCRIPTION 
   In brief, the embodiment described herein is to a valve having a mounting cup, an axially movable valve element and a resilient sealing grommet surrounding the stem of the valve element. The valve stem has sidewall openings. When the valve is axially depressed, these openings are in communication with the product to be dispensed in the pressurized can on which the valve is mounted. The product, under pressure, is forced through the valve stem openings up through a central passageway in a tubular valve stem and out of whatever dispensing actuator is appropriate for the product being dispensed. In addition to the valve stem with its sidewall openings, there is a button at the base of the valve stem that abuts under pressure against a horizontal surface of the sealing grommet in order to assure sealing of the product when in the closed state. 
   The sealing grommet has an annular interior surface that surrounds the valve stem and has an interference fit relationship with the lower portion of the valve stem from the button to at least the top of the dispensing openings in the valve stem. This interference fit is required to assure that when the stem is depressed to expose a portion of the openings to product, the result is a partial opening with a less than full dispensing rate. 
   In barrier containers, using compressed nitrogen or air, as product is dispensed, the pressure decreases. Depressing the valve to expose a portion of the valve stem opening as a function of the loss of pressure enables a relatively satisfactory steady dispensing of product during the course of dispensing product. But for this to work, the grommet has to effectively seal off the unexposed portion of the valve stem opening. The interference fit assures that partial opening result. 
   This user control is particularly important when the propellant is a compressed gas, such as air or nitrogen; but may be useful in other contexts to provide operator control over the rate at which product is dispensed. 
   The dispensing openings are elongate in the axial direction. 
   The embodiment disclosed is particularly adapted for dispensing a highly flowable product such shave gel and also a spray product such as an insecticide spray. In that embodiment, the sealing grommet has a recess in its base for receiving the valve button. The relationship between the button diameter and the grommet recess diameter is a slip fit. The result is that the walls of the recess assure stability of the valve by minimizing any tendency of the valve to tilt. 
   Recesses in the edge of the button allow product to travel past the button into the valve stem sidewall openings when the valve is open. It is important that the recesses in the button be at least equal in area to the valve stem openings so as to avoid further restriction on the flow of the product to be dispensed. 
   It is preferable for the valve stem openings to have longitudinal edges that taper outward from a minimum width at the lowest point in the opening to a maximum width at or near the top of the opening. The uppermost segment of the opening could well have straight walls. The result is an opening that is approximately an inverted truncated triangular topped by a rectangular segment. 
   A boot segment in the upper portion of the grommet engages a shoulder on the valve stem so that when user pressure on the valve is removed the boot will push the valve up into a closed state. 
   It is important that the top of the boot have an inwardly directed annular flange that snugly engages an annular recess or groove in the valve stem. This assures that the boot does not escape the shoulder under the restoring pressure exerted when the boot is fully collapsed. 
   Terminology 
   As used herein, the term “upper” and formatives thereof should be understood to refer to a location closer to the dispensing actuator; that is, the element which is usually actuated with the finger of the user. The terms “lower” and “down” and formatives thereof should be understood to refer to a location closer to the interior of the container on which the valve assembly is mounted. Most containers are stored on their base. The input end of the valve is lower in the container and the output end is at the upper end. Many products are dispensed upside down or laterally. It should be understood herein that the terms “upper” and “lower” are used to indicate relative position or direction in connection with the above convention, not with respect to the position of the container when dispensing product. 
   The term “valve” is sometimes used in a more inclusive sense and other times in a less inclusive sense. As used herein, the term “valve assembly” will normally be used to refer to the three element combination of the mounting cup, a movable valve element and a sealing grommet. The term “valve” will usually be used to refer to the combination of the movable valve element and the sealing grommet. And, to provide an appropriate distinction, the term “valve element” will be used to refer to the element around which the grommet is mounted and which is depressed in a downward direction relative to the grommet to provide an open state and when released move up relative to the grommet to provide a closed state. 
   The grommet has as its main function to seal the valve stem openings by sealing pressure between the upper surface of the button and a horizontal surface of the grommet. Thus, it is referred to herein as a sealing grommet. The upper portion of the grommet is referred to as a boot. The boot portion engages a shoulder on the valve stem. The boot is resilient and compresses when the valve is opened. The boot serves to provide a restoring force on the valve element to close the valve when finger pressure on the actuator is released. 
   There is a “full engagement” relationship between the flange  50  at the top of the boot  44  and the recess  52  in the valve stem  30 . In the embodiment disclosed, a 20 mil thick resilient material flange engages a 20 mil thick non-resilient recess. This engagement is referred to herein as a “full engagement” or as “two elements being fully engaged”. This relationship will normally be tighter than that which is called a slip fit relationship and thus is also referred to as a “snug” relation. Nominally the two dimensions being engaged are equal. There may be some slight variation depending upon the requirements of assembly and the materials used. The purpose is to provide as snug a fit as possible in order to avoid having the boot  44  slip out of engagement and move over the shoulder  48  when the valve is fully depressed. 
   The open state of the valve is normally used to refer to both fully open and partially open valve conditions. 
   A mil is a thousandth of an inch (0.001 inches). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of a valve  12 ,  14  of this invention mounted on a pressurized container. 
       FIG. 2  is a larger scale view of the valve of  FIG. 1  in a closed state showing the button  24  of the valve pressed against the horizontal ceiling  26  of the recess  40  in the grommet  14  thereby blocking product from reaching the valve stem openings  28 . 
       FIG. 3  is a view similar to that of  FIG. 2  in which the valve element  12  is fully depressed so that the entire valve stem openings  28  are exposed to the product being dispensed. This is the fully open state. 
       FIG. 4  is an elevational view of the movable valve element  12 . The recesses  32  in the button  24  are shown in  FIGS. 4 and 5  but are omitted from  FIGS. 2 and 3  to simplify presentation 
       FIG. 5  is a view along the plane  5 - 5  of  FIG. 4 .  FIG. 5  shows the top of the button portion of the valve element and the recesses  32  in the edge of the button that allow product to pass through when the valve is fully or partially open. 
       FIG. 6  is a larger scale view of the opening  28  in the valve stem showing the variable width of the opening along its elongate length and providing dimensions in one embodiment. 
       FIG. 7  is a longitudinal section view through the grommet  14  in its relaxed state. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The FIGs. illustrate a single embodiment. As shown in  FIG. 2 , the three piece valve assembly is constituted by a mounting cup  10 , a movable valve element  12  and a resilient annular sealing grommet  14 . The valve element  12  has a button  24  which fits in a recess  40  in the base of the grommet  14 . 
   The mounting cup  10  performs a known function of mounting the valve assembly on top of the container  16  in which the product to be dispensed is contained. The product  18  to be dispensed is above the piston  20  which acts as a barrier between the product  18  and the gas under pressure in the lower chamber  22 . The gas under pressure causes the piston  20  to apply pressure to the product  18 . A piston  20  barrier is shown. But as is known in the art a collapsible bag barrier can be employed. A hand operated actuator  23  is mounted on top of the valve element  12 . 
   The valve has a closed state in which the valve element  12  is in an upward position where a button  24  at the base of the valve element  12  abuts against a horizontal surface  26  at the top of the recess  40  in the sealing grommet  14 . In this sealed or closed state, the engagement between the button  24  and the grommet surface  26  blocks product from access to the sidewall openings  28  in the valve stem  30 . The valve stem  30  has two openings  28  in the embodiment shown. 
   As shown in  FIGS. 4 and 5 , the button  24  has two recesses  32  in the edge of the button so as to provide communication between the valve stem openings  28  and the product to be dispensed. These recesses  32  can best be seen in  FIG. 5  and are at the edge of the button  24  and extend through the button  24 . 
   As shown in  FIG. 3 , when the valve element  12  is depressed, the button  24  separates from the grommet surface  26 . The product under pressure can flow through recesses  32  (see  FIG. 5 ) in the edge of the button  24  through the space  33  between the button  24  and grommet surface  26  and into the valve stem openings  28 . The product is then forced through the center bore or passageway  34  in the valve stem  30  to be dispensed from the actuator  23  fitted to the top of the valve stem  30 . In the fully open state, the button  24  remains within the grommet recess  40 . 
   The sealing grommet  14  is a resilient material such as an elastomer or rubber, examples of which are sold under the trademarks Santoprene and Hytrel. As may best be seen in  FIG. 7 , the annular grommet  14  contains an inner bore  36  having a lower portion  38  which engages the lower portion of the valve stem  30  from the button  24  up to at least the upper end of the valve stem openings  28 . This engagement between the grommet bore portion  38  and the valve stem is an interference fit engagement. For example, for a valve stem having a diameter of approximately 150 mils, the diameter of the grommet portion  38  when the grommet is in its unassembled relaxed state might be about 10 mils less. This provides approximately a five mil interference fit on a radius. 
   The corner  39  of the grommet  14  is an orthogonal intersection between the bore  36  and the horizontal surface  26  of the grommet. This assures that the grommet surface  38  will be flush against the entire lower portion of the valve stem  30 . 
   When the valve is partially open, the interference fit between grommet surface  38  and surface of valve stem  30  is maintained and thus the valve stem openings  28  can be partially opened by the operator to provide selection of the rate at which product is dispensed. 
   When the valve element  12  is depressed by manual pressure of the user, the valve stem openings  28  are moved partially or wholly out of engagement with the grommet surface  38 . This movement can be a partial or a complete disengagement or opening of the openings  28 . The user can adjust the rate at which product is dispensed by the amount that the valve element  12  is moved down in an axial direction. 
   The interference fit relationship between the grommet surface  38  and the zone of the openings  28  is crucial to assure that a partial opening of the valve can be achieved. The interference fit relationship assures that the portion of the valve stem opening  28  that continues to be blocked by the grommet surface  38  will be effectively blocked and will not be opened by pressure of the product being dispensed. 
   The shape of openings  28  are shown in detail in  FIG. 6 . When compressed air or compressed nitrogen is employed, the pressure drops as product is dispensed because the volume of the pressure chamber  22  increases as the volume of the product chamber  18  decreases. Having the dimensions of the opening increase in both directions (axially and transverse thereto) as the valve is depressed provides enhanced comfort and control for the user. The opening  28  geometry shown is a truncated inverted triangle topped by a small rectangular portion. This has been found to be useful; particularly when dispensing a product such as a shave gel. 
   The grommet  14  has a recess  40  in its base into which the valve button  24  fits. The diameter of the button and the diameter of the recess  40  have a slip fit relationship. For example, a button with a 250 mil diameter and a grommet recess  40  with a 251 mil diameter is representative of the essentially slip fit relationship involved. This recess  40  helps to dimensionally stabilize the valve, minimize any tendency to tilt and thereby assists in providing control over the amount by which the openings  28  are opened and thus control of the rate at which product is dispensed. 
   The recesses  32  in the button  24  have the configuration shown in  FIG. 5  in which a protrusion  42  bifurcates the openings. This is in one preferred embodiment in order to facilitate automatic assembly. It is important, though, that the cross sectional area of the two recesses  32  openings be at least equal to the area of the two valve stem openings  28  if it is desired to avoid any additional restriction on the flow of product. 
   This resilient sealing grommet  14  has an upper boot portion  44 . The upper surface  46  of the boot  44  engages a shoulder  48  in the valve stem  30  to provide a force to assure that the valve returns to a closed state when pressure is removed from the actuator attached to the valve. An inwardly extending annular flange  50  at the top of the boot  44  engages an annular recess  52  in the valve stem  30  so as to assure that the grommet  14  will remain properly positioned relative to the valve element  12  during the opening and closing operation of the valve. 
   It is important that the thickness of the flange  50  and the width of the recess  52  have a snug relationship. In one embodiment, they are both about twenty mils. The upper end of the boot  44  is beefed up by extending it radially outward under the shoulder  48 . The full engagement of flange  50  and recess  52  together with the increased diameter of the shoulder  48  and thus increased material at the top of the boot assures that when the valve element is depressed, the boot  44  will not move up on the valve stem, over the shoulder  48 . The stability of boot top and shoulder  48  face assures that the boot  44  will appropriately compress so that the force required for returning valve  12 ,  14  to its closed state will be available when operator pressure is removed from the actuator  23 . 
   The boot  44  has a concave inner surface  54  which assures that the boot  44  will buckle out when vertical pressure is applied when the valve  12  is moved downward and thus avoid having the boot significantly resist opening of the valve. A vertical slit (not shown) in the boot  44  might be useful to ease actuation. That will depend on grommet material and boot size. The outer surface  55  of the boot wall is radially recessed from the top outer edge of the boot so that the boot wall will resist opening only enough to assure that the boot wall on compression will provide the force needed to close the valve when operator pressure is removed. 
   An annular bump  56  on the bore of the grommet  14  can be of value to prevent product from leaking up between the valve stem and grommet when the valve is in its fully or partially open state. 
   The lower stem extension  58  is to facilitate handling in assembly. The bore  34  extends below the openings  28  to reduce the amount of plastic used in molding and to facilitate cooling after molding. 
   One Example of the Embodiment Disclosed 
   In one example of this embodiment, a product useful for dispensing gel shave has the following dimensions. For clarity and ease of presentation, the FIGs. are not proportional to the following typical dimensions. 
   Grommet Recess  40 : 251 mils in diameter and 115 mils deep. 
   Button  24 : 250 mils in diameter and 50 mils thick. 
   Valve Stem  30 : 152 mils in diameter. 
   Grommet inner diameter at the lower portion  38 : 142 mils in relaxed state. 
   Center Passageway  34 : in valve stem 700 mils (this passageway is slightly tapered in order to permit removal from the mold) and thus does not have a completely uniform diameter). 
   Shoulder  46  Diameter: 230 mils. 
   Valve Stem Openings  28 : See  FIG. 6  for dimensions. 
   Boot Flange  50 : 20 mils thick by 20 mils long. 
   Stem Recess  52 : 20 mils thick by 20 mils deep. 
   A preferred embodiment has been described. However, it is apparent to those skilled in the art that certain changes can be made without departing from the teachings of the invention and the scope of the claims. 
   Most particularly, the dimensions and tolerances will be a function of the product being dispensed and most particularly viscosity of the product being dispensed, the normal desired rate at which product is dispensed and the nature of the dispensed material (that is, whether what is being dispensed is a spray or a true aerosol or liquid flow). 
   The dimensions of the sidewall openings in this valve stem and the optimum amount of the interference fit between the resilient grommet and the zone of the stem where the sidewall openings exist may vary somewhat as a function of such factors as the viscosity of material being dispensed and the pressure at which product is dispensed. 
   The recesses  40  along the edges of the button  24  could be replaced by openings through the button. But the small dimension of button and openings make recesses easier to mold.