Abstract:
A valve and concomitant method of controlling flow of a fluid with a valve comprising isolating a fluid path from a valve stem with a diaphragm in a valve body, blocking the fluid path with a plunger having a stroke of less than approximately 500 micrometers, driving the plunger with an actuator, and operating the valve at a frequency of at least approximately 20 Hz but with a flow of at least approximately 5.0E-04 kg/sec.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not Applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
   Not Applicable. 
   COPYRIGHTED MATERIAL 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention (Technical Field) 
   The present invention relates to a single stage micro- or mini-sized valve comprising a direct drive actuator, capable of rapid opening/closing transient time, and capable of working at high frequency. 
   2. Description of Related Art 
   For some applications, a rapid high-flow valve is necessary, such as for steering space vehicles and controlling equipment that requires a fast response. Conventional fluid valves are usually either fast but low-flow or slow and high-flow. One possibility is to use multistage valves with at least two stages. Unfortunately this class of valves solves the frequency problem by operating on the slave valve (pilot stage) at reduced flow and therefore higher frequency. Under these conditions the opening and closing transient time suffers an intrinsic delay that even in the case of two stages can severely limit the final obtainable frequency, as in U.S. Pat. No. 6,830,229, to Wetzel, et al. 
   The present invention achieves maximum operating speed and maximum frequency by using a single stage valve controlled by a fast direct-coupled actuator. An appropriate such actuator is disclosed in U.S. Pat. No. 6,774,539, to Guida. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention is of a valve and concomitant method of controlling flow of a fluid with a valve, comprising: isolating a fluid path from a valve stem with a diaphragm in a valve body; blocking the fluid path with a plunger having a stroke of less than approximately 500 micrometers; driving the plunger with an actuator; and operating the valve at a frequency of at least approximately 20 Hz but with a flow of at least approximately 5.0E-04 kg/sec. In the preferred embodiment, the valve provides a flow of at least approximately 1.0E-03 kg/sec. A dome shaped recess within the body accommodates the diaphragm, is conformal to the shape of the diaphragm when in an open state, and has a depth of approximately 50% of total diaphragm swing. A stem conditioner may be employed to limit down stroke of the plunger, and may be a spring, one or more valves controlling recovery time, and/or a stem with an upper and lower portion capable of telescoping operation (most preferably including a smaller valve operating only in one direction and a larger valve operating only in the other direction) 
   Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings: 
       FIG. 1  is a cross-section view of the entire valve of the invention; 
       FIG. 2  is a more detailed view of the bottom valve body; 
       FIG. 3  is a bottom block top view; 
       FIG. 4  is a top block cross-section view; 
       FIG. 5  is a cross-section view of the stroke length conditioner; 
       FIG. 6  is a cross-section view of the stroke speed conditioner; 
       FIG. 7  is an alternative embodiment of the conditioner; and 
       FIG. 8  is a cross-section view of the self-adjusting stem length device. 
   

   In the drawings, the following reference numerals are employed:
       11  Bottom valve body     12  Top valve body     13  Valve inlet     14  Valve outlet   Isolation diaphragm     16  Plunger     17  Valve seat     18  Stem     19  Stem conditioner     20  Actuator     21  Bottom block     22  Valve seat     23  Inlet port     24  Outlet port     25  Bottom inlet chamber     31  Bottom valve block     32  Flat valve seat     33  Valve inlet.     34  Inlet chamber     35  Seat step     41  Top valve block     42  Upper inlet chamber     43  Diaphragm positioning and holding recess     44  Isolation diaphragm     45  Dome shaped diaphragm stop.     46  Valve Stem     47  Stem access hole     48  Plunger     51  Plunger     52  Valve main body     53  Down stroke travel stopper     54  Valve upper body     55  Stem     56  Diaphragm     61  Conical spring     62  Top valve body     63  Stem spring collar     64  Stem     65  Plunger     66  Diaphragm conformal stop     67  Inlet chamber     71  Spring     72  Stem     73  Plunger     81  Container     82  Fluid     83  Piston     84  Valve stem     85  Conical Spring     86  One-way fast port     87  One way slow port     88  Stem aligner and stopper     89  Stroke length adjust gap   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is of a valve comprising a minimum of basic parts, thereby rendering it simple, reliable, and robust. The valve and its preferred components are illustrated in  FIG. 1 . Main body  11  serves as support to hold all other parts. Top plate  12  operates as the valve cover. Diaphragm  15  isolates the fluid path from the valve stem. Plunger  16  physically blocks the flow in conjunction with valve seat  17 , stem  18  operates the plunger  16 , actuator  20  drives the stem  18  according to the valve specifications. Stem stroke conditioner  19  can be included to match the system requirements and/or improve performance. 
     FIG. 2  is a cross-section of main body  11 , with  21  being the bulk valve body made of metal, ceramic, or composed material depending on the operation and performance required. Built into the body  21  is an inlet hole  23  for the incoming fluid to be controlled, and an outlet channel  24  that serves as the fluid exit. Concentrically to inlet port  23  is plunger seat  22 , and a chamber  25  machined in the body  21  for the double function of creating the fluid path once the valve is in open position, and permitting the motion of plunger  16  and diaphragm  15 . The chamber should be as small as possible to avoid time delay during the valve opening, but large enough to ensure an unrestricted fluid flow path. The valve seat can be shaped as round, conical, or flat depending on the application. A round seat as illustrated in  22  has the advantage of self alignment and providing a high pressure contact point. 
     FIG. 3  is a cross-section of a flat shaped valve seat, where  31  is the main valve body,  33  is the valve inlet,  34  the valve outlet,  35  is a step defining the contact surface between plunger and seat which in turn determines the closing pressure capability of the valve. (Pressure=Force/Area).  32  is the flat sealing area of the valve seat. The valve seat can be machined, cast in bulk, or added as an insert, in which case it is interchangeable. 
   The valve top body illustrated in  FIG. 4  comprises a bulk plate  41  in which there is a trough hole  47  for stem  46  to reach plunger  48 . A dome shaped recess  45  accommodates diaphragm  44  during the opening cycle. The shape of dome  45  is designed to reduce excessive stress in the diaphragm by acting as a uniform stop. To do so it must be conformal to the diaphragm shape in the open condition. To reduce the diaphragm stress, the depth of dome  45  should be about 50% of the total diaphragm swing. A shallow step  43  can be machined to recess dome  45  for the purpose of self-aligning and position-retaining diaphragm  44 . 
     FIG. 5  shows one application of stem conditioner  19 . In this instance, stem  55  is provided with a hard stop  53  that limits the down stroke of plunger  55  by reaching top valve body  54 . This may be required to avoid damage to plunger  51  and seat  32 , or in the case of flat seat  32  without plunger, damage to diaphragm  56 . 
     FIG. 6  is another application of stem conditioner  19 . In this instance a spring  61  is placed between stop  63  and top valve body  62 , which has the effect of speeding up the opening of the valve in case of an unbalanced actuator action, or if so needed in special operations. Spring  61  can be cylindrical or, to reduce space, conical as in  61 . Obviously, this spring if positioned on the other end of the stem produces the opposite action (i.e., speeding up of the closing cycle). 
   Another important use of conditioner  19  is considered in  FIG. 7 . In this instance spring  71  is located along stem  72 , with or without any stop, and provides a damping action by absorbing any excess down stroke otherwise applied directly to plunger  73 . 
     FIG. 8  shows a self-adjusting stroke amplitude application of a conditioning device  19 . In this instance spring  85  is placed inside a closed container  81 , which acts like a hydraulic damper of the same kind used with cars or door closing. Valve  87 , which controls the recovery time, is preferably sized in such a way as to recover only a small fraction of the stem length at a given frequency. The length of the stem is practically self adjusted during the first downward valve cycle because the extra length is reduced by means of upper stem portion  89  moving inside bottom stem portion  88 . This is a fast adjustment due to large one-way valve  86 . Successively during the up worth steam motion the spring  85  tries to expand back, but the amount of expansion is limited by small valve  87  preventing fluid  82  from returning to the upper part of the container  81 . 
   The overall operation of the valve of the invention is straightforward: actuator  20  keeps the valve closed by pushing on plunger  16  via stem  18  with or without the help of conditioner  19 . When actuator  20  retracts, the pressure of the fluid coming in through inlet  13  pushes upward first plunger  16  and then diaphragm  15 , permitting fluid flow through chamber  67  and out to valve outlet  14 . The stem conditioner is not necessary for the valves functioning, but may be employed to accommodate special valve applications. Plunger  16  can be conical, spherical or flat, in which case it can entirely be replaced by diaphragm  15  assuming that it can stand the compression stress imposed by stem  18 . 
   The present invention provides flow up to more then ten times greater than prior art valves operating at high frequency, i.e., &gt;20 Hz. This provides the ability to closely match load requirements (maximum efficiency) if used in conjunction with a high pressure high speed actuator as discussed above Table 1 provides a comparison between a prior art fast valve (as disclosed in U.S. Pat. No. 6,830,229) and the valve of the present invention: 
   
     
       
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 1 
             
           
           
             
                 
                 
             
             
                 
               Prior Art 
               Valve of the Present Invention 
             
           
        
         
             
                 
               Valve 
               High Pres. 
               Long Stroke 
               Units 
             
             
                 
                 
             
           
        
         
             
               Actuator Force 
               5 
               2000 
               10 
               N 
             
             
               Pressure 
               1500 
               1309878 
               2911 
               K(Pa) 
             
             
               Stroke 
               40 
               40 
               377 
               μm 
             
             
               Orifice Diameter 
               2 
               2 
               3 
               mm 
             
             
               Orifice Area 
               3.14 
               3.14 
               7.07 
               mm 2   
             
             
               Flow area 
               0.251 
               0.251 
               3.553 
               mm 2   
             
             
               Flow 
               1.0E−04 
               &gt;10X 
               &gt;10X 
               kg/sec 
             
             
                 
             
           
        
       
     
   
   Note: Frequency and flow are directly dependent. Moreover, the flow is a function of fluid density, fluid viscosity, and pressure, and therefore if the working conditions are not known it is difficult to specify exact valve performance. Only the ranges can be calculated. 
   In summary, the present invention provides the advantages of simple construction, small number of parts, relatively low fabrication cost, very high performance as to speed, pressure, temperature, and full flow path isolation, and the ability to customize performance. 
   Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference.