Abstract:
A metering valve assembly is provided with a valve stem having one or more tapered channels formed therein for selective engagement with a valve seat to provide incremental regulation of fluid flow through a valve housing. An adjustment knob provides one manner of reciprocal movement of the valve stem within the valve housing. Alternatively, the valve stem can be directly engaged for rotational reciprocal movement within the valve housing. Different embodiments of the valve stem are provided for alternate fluid flow regulation requirements. The metering valve assembly is comprised of a limited number of component parts for ease of manufacture as well as the replacement and exchange of component parts in the field.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to valve assemblies and more particularly to micro-metering valves used to regulate the micro flow rates of various fluids. 
   DESCRIPTION OF THE PRIOR ART 
   Micro-metering valves are widely used in various industries to regulate the micro flow rates of fluids ranging from liquid agricultural seed treating chemicals to medical and biochemical gas applications. Two of the more common types of micro-metering valves used are needle valves, which are comprised of elongated tapered valve stems and a valve seat; and ball valves, which are comprised of a rotatable sphere having a fluid passageway formed therethrough. Either of these valves can be constructed in an in-line or tee fashion, depending on the needs of the particular application. However, prior art micro-metering valves typically suffer from one or more of a handful of shortcomings. 
   More often than not, “micro-metering” valves provide a limited range of variable flow control. Tapered needle valves typically require a substantially elongated and tapered tip to provide a wide range of accurate flow variance. Such valves are often difficult to manufacture for a wide range of incremental flow regulation and are comprised of delicate operating components. Ball valves are typically comprised of a uniform diameter opening for the passage of fluids. Accordingly, the range of fluid flow variance is dependent upon the system&#39;s ability to make accurate and minute movements of the ball opening with respect to a valve seat. The cost and complexity of the manufacturing process for such valves can rise dramatically as the degree of accuracy increases. 
   Prior art valve systems provide limited options for the user who must repair or interchange a component part of the valve system. Most micro-metering valves are manufactured as a “closed system” that must be wholly discarded and replaced in such situations. Those valve systems which are open systems capable of refurbishment are comprised of component mechanisms whose manufacturing tolerances may be insufficient to allow for accurate and convenient component part replacement. 
   The prior art also fails to provide valve assemblies with alternate means for the movement of the valve&#39;s component parts. Most valve assemblies are provided only with a thumb-screw or handle for actuation of the valve. Accordingly, the user is often left without an alternate means for valve actuation when the primary means becomes fouled due to environmental conditions, foreign debris, or mechanical failure. Moreover, valve assemblies having a single actuation means typically lack the capability of further micro-adjustment once the primary actuation means has positioned the valve&#39;s component parts. 
   Accordingly, what is needed is a new micro-metering valve assembly that provides a wide range of variable fluid flow regulation that is also simple in manufacture and use. 
   SUMMARY OF THE INVENTION 
   The metering valve of the present invention is generally provided with an elongated valve stem having one or more generally tapered grooves formed at one end of the valve stem and mating threads formed in the opposite end. The valve stem is at least partially disposed within a valve housing having an inlet portion, an outlet portion, and an adjustment portion. The adjustment portion is generally provided with an adjustment knob that threadably engages the valve stem at one end. An adjustment coupling is secured at one end to the adjustment portion of the valve housing and is rotatably secured at its opposite end to the adjustment knob. In this arrangement, rotation of the adjustment knob provides for reciprocal, non-rotational movement of the valve stem within the valve housing. Optionally, the adjustment end of the valve stem can be shaped to receive a rotating means to initiate rotational reciprocal movement of the valve stem with respect to the valve housing and the adjustment knob. 
   The valve stem is selectively coaxially received by a valve seat disposed within the output portion of the valve housing. Reciprocal movement of the valve stem within the valve housing positions the tapered channel in the valve stem with respect to an opening in the valve seat. Accordingly, fluid flow through the valve assembly can be incrementally regulated. Full advancement of the valve stem within the housing engages a generally tapered shoulder portion of the valve stem with the valve seat to provide a positive stop for the fluid flow. A hip member formed in the valve stem adjacent to the shoulder member is sized to prevent the complete withdrawal of the valve stem through the adjustment coupling member. Alternate valve stems having different flow regulation features can be selectively exchanged to adapt the function of the valve assembly&#39;s flow regulation. 
   The metering valve is assembled with a limited number of component parts to simplify the manufacturing process. Each of the component parts are assembled and disassembled easily for replacement or exchange of component parts in the field as circumstances dictate. 
   It is therefore a principal object of the present invention to provide a metering valve that is capable of a wide range of fluid flow adjustment. 
   A further object of the present invention is to provide a metering valve that is simple in manufacture and use. 
   Yet another object of the present invention is to provide a metering valve that provides for easy disassembly and interchangement of component parts. 
   Still another object of the present invention is to provide a metering valve that provides for multiple methods of valve stem advancement and retraction. 
   A further object of the present invention is to provide a metering valve capable of regulating the flow of a wide range of liquids and gases. 
   These and other objects will be apparent to those skilled in the art. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  depicts one possible application for the metering valve of the present invention; 
       FIG. 2  is a perspective view of the metering valve of the present invention in an assembled form; 
       FIG. 3  is a side cutaway view of the metering valve of the present invention; 
       FIG. 4  is a perspective exploded view of the component parts of at least one embodiment of the metering valve of the present invention; 
       FIG. 5  depicts a partial cutaway view of the valve stem and valve seat of one embodiment of the present invention; and 
       FIG. 6  is a partial cutaway view of another possible embodiment of the valve stem and valve seat of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The numeral  10  refers generally to the metering valve assembly of this invention as depicted in  FIGS. 1-6 . The valve assembly  10  is provided with an elongated valve stem  12  having an adjustment end  14  and a regulating end  16 . The regulating end  16  of the valve stem  12  is shaped to be releasably and slidably received within the opening of a valve seat  18 . In a preferred embodiment, the adjustment end  14  of the valve stem  12  is slidably received through an adjustment coupling member  20 . The adjustment end  14  is then threadably received by an adjustment knob  22 . The adjustment knob  22  is provided with an open inner portion for at least partially receiving the upper end of the adjustment coupling member  20  therein. A first generally annular channel  24  is formed within the open inner chamber of the adjustment knob  22 . A second generally annular channel  26  is formed within the periphery of the upper end of the adjustment coupling member  20  so that the first and second channels  24  and  26  are positioned closely adjacent one another when the adjustment knob  22  and the adjustment coupling member  20  are mated together. The first and second channels  24  and  26  are sized to receive a generally annular retention ring  28 . The retention ring  28  helps secure the adjustment knob  22  and the adjustment coupling member  22  in rotatable connection with one another. 
   A valve housing  30  is provided to encase the inner working members of the valve assembly  10  and provide a fluid passageway  32 . It is contemplated that the housing  30  could be formed in nearly any configuration as the circumstances so require; however, in a preferred embodiment, the housing  30  is provided in the shape of a tee connector. The housing  30 , as depicted in  FIGS. 2-4 , is provided with an adjustment end  34 , a fluid input end  36 , and a fluid output end  38 . The adjustment end  34  is open and preferably provided with mating threads, or other known mating structures, to receive the lower threaded end of the adjustment coupling member  20 . The fluid input end  36  is open and preferably provided with any known mating structure, such as mating threads, to operatively connect the valve assembly  10  to a fluid source. The fluid output end  38  is also open and preferably provided with a mating structure, such as mating threads, to releasably engage an output coupling member  40 , which is operatively connected to one or more known fluid dispersal devices. With the output coupling member  40  coupled to the fluid output end  38 , the valve seat  18  is firmly secured in an operational position within the valve housing  30 , as depicted in FIG.  3 . 
   In use, fluid is provided from a fluid supply, such as the applicator  42  depicted in FIG.  1 . The fluid applicator  42 , which is provided with a holding tank  44 , a strainer  46 , and pump member  48 , is a typical example of an agricultural use for the valve assembly  10 . However, it is contemplated that the valve assembly  10  will, with little, if any, modification, be appropriate for use in most gas and liquid applications, such as medical and biochemical gas applications, research laboratory sampling, and other such uses in a varying array of fields. In the example depicted, the pump member  48  draws the liquid chemical from the applicator  42  and delivers it to the fluid input end  36  of the valve housing  30 , introducing the fluid to the fluid passageway  32 . 
   By rotating the adjustment knob  22  in a counterclockwise direction, the user incrementally advances the valve stem  10  in a linear direction toward the valve seat  18 . Continued rotation of the adjustment knob  22  will dispose the regulating end  16  of the valve stem  12  within the opening of the valve seat  18  until the tapered shoulder portion  50  of the valve stem  12  is engaged with the valve seat  18 . In this position, fluid is prohibited from passing through the valve seat  18  from the fluid passageway  32 . As the user rotates the adjustment knob  22  in a clockwise direction, the regulating end  16  of the valve stem  12  is incrementally withdrawn from within the opening of the valve seat  18 . An elongated groove  52 , which is formed within the regulating end  16  of the valve stem  12 , provides the pathway in which the fluid is permitted to travel from the fluid passageway  32  to the open interior of the output coupling member  40 . Preferably, the elongated channel  52  is tapered in shape and extends longitudinally along the valve stem  12  so that the aperture through which the fluid passes from fluid passageway  32  into the open inner chamber of output coupling member  40  gradually increases as the user withdraws the regulating end  16  of the valve stem  12  from within the valve seat  18 . The rate of groove taper per unit length is preselected to provide the desired ratio of rotation of adjustment knob  22  to fluid flow. It is preferred that the regulating end  16  of the valve stem  12  be capable of complete withdrawal from within the valve seat  18  to allow for the purging of any obstructions or debris from the valve seat  18  and the fluid passageway  32 . 
   Where a large volume of fluid flow is required, the regulating end  16  of the valve stem  12  can be provided with a plurality of elongated channels  52 .  FIG. 6  depicts one such embodiment where the regulating end  16  is provided with a first elongated channel  52  and a second elongated channel  52 ′. Moreover, it is contemplated that the shapes of the channel members  52  and  52 ′ can be provided in any length, width and depth permitted by the size of the regulating end  16  of the valve stem  12  in order to vary the manner in which the fluid flow is regulated. It is further contemplated that the shape of the channel members  52  and  52 ′ can be provided in a gradual taper, a stepped fashion, or any other such shape as desired to provide a variable and wide range of incremental flow rates. 
   To prevent the passage of the fluid out of the valve assembly  10  from between the valve stem  12  and the adjustment coupling member  20 , a generally annular recess  54  is formed in the valve stem  12  as shown in FIG.  3 . The annular recess  54  is shaped to receive an O-ring  56  or similar known sealing device. It is preferred that the annular recess  54  and the O-ring  56  be positioned so that they are disposed within the opening of the adjustment coupling member  20  when the valve assembly  10  is in use. Engagement of the O-ring  56  with the inner walls of the adjustment coupling member  20  and the annular recess  54  substantially prevents fluid passage and further assists in preventing rotation of the valve stem  12  when the adjustment knob  22  is rotated. However, it is contemplated that the O-ring  56  would provide insufficient frictional engagement with the inner walls of the adjustment coupling member  20  to prevent the unintended withdrawal of the valve stem  12  from the valve assembly  10  through the occurrence of a dramatic increase in fluid pressure or other similar event. Accordingly, it is preferred that a hip member  58  be formed in the valve stem  12 . The hip member  58  should be provided with a shape and/or diameter that is incapable of passing through the opening of the adjustment coupling member  20 . In this manner, a positive stop is provided to prevent the unintended withdrawal of the valve stem  12 . 
   Adjustment knob  22  is preferably provided with an indicator  60  to provide the user a point of reference regarding the number of rotations performed. A calculation of the corresponding relationship between the size of the elongated channel member  52 , the sizes and geometry of the adjustment knob  22  and the adjustment end  14  of the valve stem  12 , along with the pressure at which the fluid is supplied to the valve assembly  10 , will provide a correlation between the number of turns of the knob  22  and the volume of fluid flow through the valve system  10 . A groove  62 , formed in the end  14  of the valve stem  12 , provides an aligning reference to use in conjunction with the indicator  60 . 
   It is preferred that the groove  62  be formed in a shape that can be received by a screwdriver or other such tool so that the valve stem  12  can be rotated with respect to the adjustment knob  22  and the adjustment coupling member  20 . This provides a second manner in which the valve stem  12  can be moved reciprocally with respect to the remaining structural components of the valve assembly  10 . Accordingly, the user will be able to make minute adjustments of the location of the valve stem  12  with respect to the valve seat  18  and/or the adjustment knob  22  with relative ease, regardless of operating conditions or location. Moreover, the channel  62  provides a manner in which the user can clean and repair the valve assembly  10  if the adjustment knob  22  and the valve stem  12  have become fouled with dirt or other debris and are no longer rotatable with respect to one another. 
   The limited number of functional parts to the valve assembly  10  provides ease of manufacture as well as assembly and use. The valve assembly  10  is easily disassembled to allow for cleaning and maintenance as well as the exchange of different component parts, such as a valve stem having a tapered regulating end portion  16  or a valve stem with multiple channel members  52  and  52 ′, for a valve stem  12  having only one channel member  52 . Accordingly, it is further contemplated that the respective diameters of the opening in valve seat  18  and the regulating end portion  16  of the valve stem could be fabricated to be larger or smaller to further provide an additional interchangeable variable flow system. 
   In the drawings and in the specification, there have been set forth preferred embodiments of the invention; and although specific items are employed, these are used in a generic and descriptive sense only and not for purposes of limitation. Changes in the form and proportion of parts, as well as substitute of equivalents, are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims. 
   Thus it can be seen that the invention accomplishes at least all of its stated objectives.