Abstract:
A metering valve having a contiguous double wall structure including an inner wall defining the metering chamber and an outer wall which defines a crimping and support wall against which the inner rim of the mounting cup of the container can be crimped. The outer wall may be maintained at the same diameter and thickness for use with generally any mounting cup which are approximately an inch in diameter as well as any mounting process and machinery. The inner wall may however be sized differently in order to accommodate different dosages for metering of product. A radial space between the inner and outer wall permits the both the axial elongation of the metering chamber as well as a radial expansion of the inner wall and hence the valve chamber relative to the outer wall due to the space between the inner and outer wall.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a metering valve for dispensing a pressurized product, generally an aerosolized liquid from a spray can type container where a discrete, metered dosage is dispensed each time a user actuates the metering valve. 
       BACKGROUND OF THE INVENTION 
       [0002]    Metering valves for spray cans are readily available in the marketplace which are constructed to allow a discrete, or pre-proportioned amount of product to be dispensed at each actuation of the valve control push-button. Such metering valves generally comprise a valve body which is associated in a sealed relationship with the mounting cup of the container or can by means of a folded seam or crimped collar. Within the valve body is defined a valve chamber in which an axially slidable valve stem is pushed down by a user against the bias of a valve spring. 
         [0003]    Inside the valve chamber there is generally a lower inlet which may include a ring seal adjacent the inlet, where the ring seal is adapted for circumferential engagement with the valve stem, in contact relationship therewith, when the valve stem is in its dispensing position. Upon actuation of the valve stem the metering chamber is isolated from the main reservoir of the container and placed in communication with the outside environment to define a dispensing state. When the stem is released, the valve chamber again communicates with the main reservoir to permit the valve chamber to be recharged and cuts off communication with the outside environment. 
         [0004]    A drawback associated with prior art metering valves is that such valves have a tendency to “throttle”. That is, due to a poor or an improper valve design, it is possible for an operator to partially depress the valve stem and establish a product flow path from the interior cavity of the aerosol container through the metering valve and out through a spray button or actuator affixed to the stem of the aerosol valve, prior to the valve stem sealing the inlet to the valve housing, so that product may be continuously discharged out through the aerosol valve. As a result of such “throttling”, the operator is able to dispense a continuous discharge of product from the aerosol container via the metering valve rather than meter a desired amount. This results in the inadvertent discharge of excess product form the aerosol container which is wasteful and generally to be avoided. 
         [0005]    Some prior art designs utilize a frictional sealing fit between two plastic valve components to separate the contents of the container from the metering chamber. This arrangement requires that a valve spring, accommodated by the valve, be sufficiently forceful to overcome the interference fit of this sealing device upon the valve closing sequence. Apart from being subject to size and hardness changes due to immersion in the product, this design mandates extremely close tolerances of the mating components and critical alignment of molded parts during the valve assembly operation. Also, insufficient return force, or pre-load, on the valve spring can cause failure of the valve stem to return to an initial closed position after initial depression. Failure to observe these manufacturing tolerances, pre-load and alignment criteria leads to an inaccurate metered spray or a valve which will not “shut-off” and thus result in the total release or dispensing of the entire product contents. 
         [0006]    It is to be appreciated that such metering valves must be manufactured so as to accommodate different volumes of product which a manufacturer desires to dispense with each actuation. With the known metering valves, it happens that, where the useful volume of the metering chamber is to be changed, i.e., when it is desired to change the amount of product dispensed at each actuation, the cylindrical valve body must be entirely redesigned and manufactured with such a volume in mind and/or replaced as a whole. 
         [0007]    It follows therefore, that in order to change the dispensed proportion of product the valve body must be entirely re-manufactured with the thickness of the valve body walls being adjusted thicker or thinner, and/or the length of the entire metering valve body being changed and the majority of the metering valve components also have to be replaced with others having different dimensions which creates a problem both as regards to production and inventory. 
         [0008]    Also, it is well known in the industry that inadequate sealing engagement and material incompatibility between the valve stem and the seal ring, and/or the valve chamber inlet, when the valve is actuated can lead to very undesirable results of inadvertent over-dispensing of the product as the product leaks from the container reservoir through the poor seal between around the valve stem and into the valve chamber during an actuated state of the valve. 
       OBJECTS AND SUMMARY OF THE INVENTION 
       [0009]    Wherefore, it is an object of the present invention to overcome the above noted drawback associated with the prior art aerosol metering valves. 
         [0010]    Yet another object of the present invention is to provide a metering valve assembly which reliably, consistently and accurately dispenses a desired quantity of the product contents from the metering valve assembly. 
         [0011]    A still further object of the present invention is to provide a metering valve assembly which can be reliably manufactured while minimizing the degree of inspection required for manufacture of the metering valve assembly. 
         [0012]    A further object of the present invention is to provide a metering valve assembly which prevents inadvertent “throttling” of the metering valve assembly by an operator. 
         [0013]    Yet another object of the present invention is to provide a metering valve assembly which is securely affixed to the valve housing and, following insert of the valve housing onto a container, the metering valve assembly establishes a flow path with the internal cavity of the container to facilitate pressuring of the container with the product to be dispensed during the manufacturing process. 
         [0014]    The general operation of this metering valve is similar to that of conventional valves. With the stem in an upper position biased by the valve spring, the metering chamber is in communication with a container reservoir or interior and consequently the product flows into and fills the metering chamber. By depressing the stem with a depressing action which overcomes the bias of the valve spring, the stem is moved downwards to engage and shut off the communication between the metering chamber and the interior of the container. At a point following establishment of a seal between the tail piece of the valve stem and the seal ring, the valve stem is moved further downwards so that the metering chamber now communicates with the radial holes in the valve stem which allow the product to be dispensed out through the main passageway of the valve stem and into the atmosphere. The timing between the initial sealing of the metering chamber from the product reservoir and the dispensing of the product is critical since if the seal is not established before the product is dispensed, the accuracy of the metering valve is compromised. 
         [0015]    The present invention utilizes a contiguous double wall structure including an inner wall defining the metering chamber and an outer wall which defines a crimping and support wall against which the inner rim of the mounting cup of the container can be crimped. The importance of the connected inner and outer walls is that the outer wall may be maintained at the same diameter and thickness for use with generally any mounting cup which are approximately an inch in diameter as well as any mounting process and machinery. The inner wall may however be sized differently in order to accommodate different dosages for metering of product. Importantly there is a radial space between the inner and outer wall which permits the both the axial elongation of the metering chamber as well as a radial expansion of the inner wall and hence the valve chamber relative to the outerwall due to the space between the inner and outer wall. 
         [0016]    Additionally, the present invention utilizes a seal ring placed in the bottom of the inner chamber which has an inner, intermediate embossment formed in the inner wall thereof. The seal ring is made of a relatively flexible material such as polyethylene as compared with the valve body and the seal ring and intermediate embossment acts in cooperation with a cylindrical tail end of the stem in order to create a sealed engagement between the protuberance and the valve stem when the valve stem is in the depressed i.e. actuated position so that fluid cannot communicate from the main chamber into the valve chamber. The embossment and seal ring also facilitates a release of the sealed engagement when actuating pressure on the valve stem is released and the valve spring axially biases the stem into the upward position so that product from within the container can now communicate and refill, i.e., charge the metering chamber for the next dose. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a cross sectional elevation view of the metering valve  1  of the present invention in an unactuated state; 
           [0018]      FIG. 2  is a cross sectional elevation view of the metering valve  1  in an intermediate state where the lower seal is engaged, but product is not yet dispensed; 
           [0019]      FIG. 3  is a cross sectional elevation view of the metering valve  1  in an actuated or depressed state; 
           [0020]      FIG. 4  is an elevation view of the valve stem  7  of the metering valve  1 ; and 
           [0021]      FIGS. 5A and 5B  are a top plan view and cross-section view respectively of the seal ring  15 ; 
           [0022]      FIGS. 5C and 5D  are a cross-sectional view of a second embodiment of the seal ring  15 ; and 
           [0023]      FIGS. 6A and 6B  are a top plan view and cross-section view respectively of the valve body. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]      FIGS. 1-3  show a metering valve  1  of the present invention for a product which is pressurized within a main reservoir R of a container or can (not shown). In general, the metering valve  1  includes a valve body  3  defining a valve chamber  5 , a valve stem  7  having a main passageway  9  for expelling the pressurized product from the metering valve  1  chamber, and a valve spring  11  for biasing the valve stem  7  against an upper gasket  13  of the metering valve  1 . Also, a seal ring  15  is positioned at the bottom of the metering valve  1  chamber adjacent a product inlet  16  to the valve chamber  5  and surrounding the valve stem  7  in order to prevent passage or leakage of product from the inlet into the valve chamber  5  when the valve is in a product dispensing state. 
         [0025]    The valve works in the following manner, with the seal ring  15  inserted into the valve chamber  5 , the valve spring  11 , generally a compression spring, sits on a top surface  47  of the seal ring  15  and, according to a desired pre-load, provides an upward bias to the valve stem  7 . Consequently, the valve spring  11  and the pre-load compression also causes a face seal between the outer surfaces of the seal ring  15  and the inner surfaces of the valve chamber  5  to prevent the leakage or passage of product or gas around the seal ring  15 . In the closed state shown in  FIG. 1 , as opposed to the product dispensing state in  FIG. 3 , the valve stem  7  is maintained by the valve spring  11  so that the stem inlets  17  which allow product into the main passage of the valve stem  7  are above, and separated from the valve chamber  5  by the upper gasket  13 . In this closed state, a tail piece of the valve stem  7  is spaced from the seal ring  15  and the lower portion of the metering valve chamber  5  communicates directly with the product inlet  16  so that product from the reservoir of the can or container may enter into the valve chamber  5  and thus charge the metering valve  1 . 
         [0026]    In the product dispensing state, a force F as shown in  FIG. 2  is applied to the valve stem  7  and the valve stem  7  is forced or pushed downward against the upward bias of the valve spring  11 . Initially, when the valve stem  7  is pushed down, i.e. actuated, the tail portion  19  of the valve stem  7  comes into radial contact with the seal ring  15  to block, or cut off, the metering valve chamber  5  from the product inlet  16  and the main product reservoir R in the container. Subsequent to the establishment of this seal between the seal ring  15  and the tail portion  19  of the valve stem  7 , the stem inlets  17  connected to the main passageway  9  of the valve stem  7  are lowered below the upper gasket  13  and into the valve chamber  5  itself. Now, as seen in  FIG. 3 , the product which is contained and isolated and under pressure in the valve chamber  5  due to the radial engagement between the seal ring  15  and the tail portion  19  of the valve stem  7  is expelled from the valve chamber  5  through the valve stem  7  inlets and dispensed to the user out the valve stem  7  main passageway  9 . 
         [0027]    When the user removes force F from the valve stem  7 , the compression spring returns the valve stem  7  to the closed state of the valve where the stem inlets  17  slide by the upper gasket  13  and out of communication with the valve chamber  5 . Subsequently, the tail portion  19  of the valve stem  7  is raised out of contact with and above the seal ring  15  so that pressurized product is then again permitted to flow through the product inlet  16  and into the chamber  5  from the main reservoir R. Thus, the valve chamber  5  is again charged with pressurized fluid awaiting the next depressive force of the valve stem  7  by the user. 
         [0028]    Now in further detail, turning to  FIG. 4  the valve stem  7  is defined about a longitudinal axis A and has an upper portion  24 , an intermediate portion  22  and a lower portion  26 . The upper portion  24  includes the valve stem inlets  17  and the main passageway  9  leading to a valve stem  7  outlet where the product is dispensed. The valve stem inlets  17  are generally formed perpendicular to the main passageway  9  and the longitudinal axis A and communicate directly with the main passage coaxial along the axis A and extending from an intermediate portion  22  of the valve stem  7  to the valve stem  7  outlet. 
         [0029]    The valve stem  7  is also provided with an external embossment  23  at the intermediate portion  22  of the valve stem  7 . The embossment  23  provides an upper step  25  and a lower step  27  where the lower step  27  provides a surface against which the top end of the spring abuts so as to influence the valve stem  7 . The upper step  25  of the embossment  23  provides a surface which abuts against a lower surface of the upper gasket  13  when the valve stem  7  is in the closed state. 
         [0030]    The tail portion  19  of the valve stem  7  is formed on the lower portion  26  of the valve stem  7 . The tail portion  19  may include two or three constant diameter cylindrical sections separated by tapered sections a largest section  32 , a middle section  34  and a smallest end section  36 . The cylindrical sections are each of a different diameter with largest section  32  adjacent to the intermediate portion  22  of the valve stem  7  is substantially the same diameter as the inner diameter of the valve spring  11  in order to frictionally engage the spring  11  and maintain its relative radial and axial position on the valve stem  7  and in the valve chamber  5 . The middle section  34  is sized so as to provide a particularly close interference fit with the seal ring  15  and isolate the valve chamber  5  from the product inlet  16  and main reservoir R when the valve is in the product dispensing state. 
         [0031]    The end section  36  of the tail portion  19  has a diameter that is slightly smaller than the inner most diameter of the seal ring  15  in order to provide a spacing therebetween for product flow from the main product reservoir through the product inlet  16  into the metering valve  1  chamber when the valve is in the closed state as described above. The taper section  31  between the middle section  34  and the smallest end section  36  of the tail portion  19  ensures a smooth transition between the cylindrical sections  29  occurs during the sliding interfering contact between the seal ring  15  and the tail portion  19 . In other words, when the valve is actuated as in  FIG. 3  the tail portion  19  slides relative to the seal ring  15  so that the tapered section passes downward through the seal ring  15  and provides a smooth and consistent sliding transition to the interference fit between the seal ring  15  and the middle section  34  of the tail portion  19 . 
         [0032]    Better seen in  FIGS. 5A-5B , the seal ring  15  is fabricated from a particularly softer and generally more elastic material than the harder and stiffer polymers used in making the valve stem  7  and the metering valve  1  body. The seal ring  15  may be fabricated for example out of polyethylene. The seal ring  15  is defined by a hollow cylindrical main body  41  having an outer surface  43  with a substantially flat profile to frictionally engage with a wall of the valve chamber  5 , an inner surface  45  for radially engaging with the tail portion  19 , a top surface  47  and a bottom surface  49 . The seal ring  15  is positioned inside the metering valve  1  chamber so that the bottom surface  49  is in contact with a corresponding bottom surface  50  of the metering valve  1  chamber to form a face seal therebetween maintained by the pre-load of the valve spring  11  and the outer surface  43  rests against the inner wall of the metering valve  1  chamber and the bottom end of the valve spring  11  sits atop the top surface  47  of the seal ring  15 . 
         [0033]    The inner surface  45  of the seal ring  15  is further formed with a circumferential inner embossment  51  which facilitates the sealing of the passage through the seal ring  15 . It is this inner embossment  51  which generally provides the frictional engagement and interference fit with the above discussed components i.e. the tail portion  19  and middle section  34  of the valve stem  7 . Where the inner diameter d of the inner embossment  51  is approximately 0.100-0.110 inch and more preferably about 0.102-0.105 inch, the inner diameter of the remaining portion of the seal ring  15  is about 0.100-0.150 and more preferably about 0.135-0.145 inch. The diameter of the middle section  34  of the tail portion  19  is chosen so that a desired interference occurs between the inner embossment  51  of the seal ring  15  the tail portion  19  and the middle section  34  of the valve stem  7  to create the lower seal between the valve chamber  5  and the reservoir R. 
         [0034]    An upper portion  53  of the inner surface  45  of the seal ring  15  may be generally flat whereas the lower portion  55  of the inner surface  45  is shown having a substantially circumferentially concave curved surface  57  and is important in that the curved surface  57  facilitates mold extraction of the seal ring  15 . It is to be appreciated that as shown in  FIGS. 5C-D , the curved surface  57 ′ may be convex in nature as well for the same reason. 
         [0035]    The inner embossment  51  of the seal ring  15  is a radially inwardly extending protrusion from the inner surface  45  of the seal ring  15  towards the axis A of the valve. The inner embossment  51  tapers from a thicker portion adjacent and integrally connected to the inner surface  45  of the seal ring  15  to a thinner free end  59  for contacting the valve stem  7  and defining the innermost diameter of the seal ring  15 . This tapering profile is important to provide a relative flexibility to the free end  59  of the inner embossment  51  which seals, and unseals, with the middle section  34  of the valve stem  7  during actuation and release respectively. It is to be appreciated that other shapes and profiles for the inner embossment  51  may be utilized as well. 
         [0036]    The metering valve body  3  shown in  FIGS. 5A ,  5 B is composed of a series of castellations  61  along a top edge for direct engagement with the inner walls of the mounting cup to assist in crimping and to maintain the metering valve  1  body and valve stem  7  and other components in alignment and engagement with the mounting cup. These castellations  61  extend outwards having a larger diameter than a lower portion  55  of the metering valve body  3  in order to permit the crimping of the center turret of the mounting cup around and to the metering valve body and to provide for through-the-valve (TTV) filling. 
         [0037]    The valve body  3  is defined by an outer wall  63  and an inner wall  65  where the inner wall  65  specifically defines the valve chamber  5  and is radially spaced from the outer wall  63  where the outer wall  63  is generally maintained at a desired circumference in order to provide the appropriate size and alignment of the castellations  61  for crimping to the mounting cup. This radial space S between the inner wall  65  and the outer wall  63  is important because it permits the inner wall  65  to be readily manufactured in a variety of diameters relative to the central axis A of the valve which would enable a manufacture to vary the size of the valve chamber  5  by moving the inner wall  65  of the valve body  3  in or out relative to the axis without moving the outer wall  63 . 
         [0038]    Thus, with the same outer dimensions, i.e. the outer wall  63  remaining the same for purposes of attachment and crimping to the mounting cup, the inner wall  65  may be varied in order to provide different volumes of valve chambers for particularly different products. The inner wall  65  defines the valve chamber  5  and a passage and an inlet passage leading thereto. The inlet passage is generally of a smaller diameter and connects with the valve chamber  5  at a step portion against forming the bottom wall of the valve chamber  5  against which the seal ring  15  abuts. The inner wall  65  of the valve body  3  extends upward generally at a larger diameter than the the inlet passage  16  in order to define the metering chamber  5 . Besides being radially expandable depending of the product to be used, this metering chamber  5  may also be made longer or shorter, i.e. extending a longer or shorter distance along the longitudinal axis A of the valve in order to further enlarge or reduce the volume of the chamber. 
         [0039]    The valve spring  11  is situated between the lower step  27  formed by the intermediate embossment  23  on the valve stem  7  and the top surface  47  of the seal ring  15 . Where the spring is in compression at all times after manufacture of the metering valve  1  and mounting cup, the pre-load on the spring will maintain the seal ring  15  in the face seal against the intermediate step of the metering valve  1  body at all times. Also, an inward extending chamber protrusion  67  assists in maintaining and setting the seal ring  15  in its appropriate position adjacent the inlet  16 . 
         [0040]    Since certain changes may be made in the above described and improved valve body  3  and fitment  1 ,  51  without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.