Abstract:
The present invention overcomes deficiencies in the art. A valve device is provided that includes a valve body defining a chamber for receiving fluid to be dispensed from the valve device, a seal contact surface located on the valve body, near a location where fluid discharges from the chamber, one or more grooves within the seal contact surface, and a reciprocatable piston rod supporting a seal that selectively contacts the seal contact surface, the piston rod being received at least partially within the chamber. The groove and seal have structural configurations that prevent the seal from fully blocking the groove when the piston rod is in a first position where the seal contacts a portion of the seal contact surface including the groove, and as a result fluid within the chamber may enter the groove when the piston rod is in this first position. A method of dispensing fluid in variable amounts is also provide that includes the steps of providing a valve device as described above, repeatedly moving the piston from the first position to the second position, thus allowing fluid within the chamber to enter the groove and then be swept out of the valve device in a dropwise manner.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Blending of fluids is important in many different industries. Blending can be done either in an approximated manner or in an extremely precise manner depending upon the use of the final product. For example, blending in a precise manner is often performed when different colors of base fluids, having otherwise similar physical properties, are mixed. If the goal is to produce a final mixture having a desired color, then precise measuring of the base fluids is critical. 
         [0002]    When precise blending is performed, the blending process is often gravimetric. A receiving container is placed upon a precise measuring scale. Base fluids from multiple sources are added individually to the container through a metering pump and valve system. Each source may have its own dedicated metering system or a single metering system being fed from multiple fluid sources may by used. 
         [0003]    Valves used in the metering systems often operate in a pressure release manner. Such a valve includes a piston and piston rod holding a seal, wherein the seal stops flow when the valve is in a closed position. The piston and the rod are biased to the closed position by spring force. By applying pressure into the valve via compressed air or another fluid, in a space on the opposite side of the piston from the spring(s), the rod seal is lifted out of a bore, and thus, opens the valve to a certain degree, dependent on the amount of air pressure applied. 
         [0004]    When a selected amount of fluid of a particular type is to be added in the receiving container, pressure is first applied at a high level in order to open the valve wide, and move most of the required fluid into the receiving container quickly. As the desired amount of fluid is approached, pressure is reduced so that the flow rate of added fluid is also reduced. However, even at this lower rate, it is difficult to add very small amounts of fluid. A drawback of the art, at present, is that the precision of the gravimetric scale is greater than the precision of available valve systems. An improved distribution valve is desired. 
         [0005]    One technique that has been tried with existing valves is to repeatedly pulse the valve with air pressure, so as to open and close the valve quickly. Unfortunately, this does not produce drops reliably in common valves. What is further desired is a new method of using an improved valve which can deliver fluid repeatedly and reliably in a precise dropwise manner. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The present invention overcomes deficiencies in the art. A valve device is provided that includes a valve body defining a chamber for receiving fluid to be dispensed from the valve device, a seal contact surface located on the valve body, near a location where fluid discharges from the chamber, one or more grooves formed in the seal contact surface, and a reciprocatable piston rod supporting a seal that slidingly contacts the seal contact surface, the piston rod being received at least partially within the chamber. 
         [0007]    The groove(s) and seal have structural configurations that prevent the seal from fully blocking the groove when the piston rod is in a first position where the seal contacts a portion of the seal contact surface including the groove, and as a result fluid within the chamber may enter the groove when the piston rod is in this first position. The piston rod and seal can also be moved to a second position on the seal contact surface that is downstream of the groove. Fluid flow out of the chamber is fully prevented when the piston rod and seal are in the second position. 
         [0008]    A method of dispensing fluid in variable amounts is also provided that includes the steps of providing a valve device as described above, repeatedly moving the piston from the first position to the second position, thus allowing fluid within the chamber to repeatedly enter and pass through the groove and valve device in a dropwise manner. 
         [0009]    The method further includes the step of moving the piston rod to a third position, upstream of the groove, where the seal is spaced apart from the seal contact surface, thus allowing fluid to exit the valve in a stream. 
         [0010]    These and other features, aspects and advantages of the present invention will be fully described by the following description, appended claims, and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    In the following figures, some of the same or similar types of elements or corresponding parts are provided with the same reference numbers in order to prevent the item from needing to be reintroduced. 
           [0012]      FIG. 1  is a schematic representation of a system and method for distributing fluids; 
           [0013]      FIG. 2  is an exploded view of a first embodiment of the valve device of the present invention; 
           [0014]      FIG. 3A  is a cross sectional view of the first embodiment of the valve device with the piston rod in a first position; 
           [0015]      FIG. 3B  is a detailed view of a portion of  FIG. 3A ; 
           [0016]      FIG. 4A  is a cross sectional view of the first embodiment of the valve device with the piston rod in a second position; 
           [0017]      FIG. 4B  is a detailed view of a portion of  FIG. 4A ; 
           [0018]      FIG. 5A  is a cross sectional view of the first embodiment of the valve device with the piston rod in a third position; 
           [0019]      FIG. 5B  is a detailed view of a portion of  FIG. 5A ; 
           [0020]      FIG. 6  is a cross sectional view of a variation of the first embodiment of the valve device; 
           [0021]      FIG. 7  is a cross sectional view of another variation of the first embodiment of the valve device; 
           [0022]      FIG. 8  is an exploded view of a second embodiment of the valve device of the present invention; 
           [0023]      FIG. 9  is a cross sectional view of the second embodiment of the valve device with a piston rod in a first position; 
           [0024]      FIG. 10  is a cross sectional view of the second embodiment of the valve device with the piston rod in a third position; and 
           [0025]      FIG. 11A  is a cross sectional view of an insert component in the second embodiment of the invention; and 
           [0026]      FIG. 12  is a top view and detailed portion of the insert component. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    An improved system and method for distributing fluids is provided. Referring to  FIG. 1 , the system  10  shown schematically, in general, includes a receiving container  12  for mixed fluids, one or more improved dispensing valve devices  14 , described in more detail below, pumps  16 , containers holding base supply fluids  18 , compressed air supplies  20  and associated solenoids  22  for the valves and pumps, a scale  24 , and computer-based controls  26  that receive input from an operator and control the system  10  accordingly. 
         [0028]    Improved distribution is facilitated by a first embodiment of the improved dispensing valve device  14  shown in  FIG. 2 , and described in more detail below. The valve device  14  includes, amongst other components, a distal end cap  30 , a main body  32 , a seal contact surface  34 , a piston rod  36  supporting an O-ring seal  114 , a spring and piston system  38 , and a proximal end cap  40 . The term “downstream” is used herein and refers to moving away from the portion of the main body that holds the liquid being dispensed. 
         [0029]    The system  10  for distributing fluids is shown in  FIG. 1 . A scale  24  is situated on a stationary surface, for example, the floor in a factory. A receiving container  12  is placed on top of the scale  24  such that the weight of base fluids added to the receiving container  12  may be measured. One or more improved dispensing valve devices  14  of the present invention are situated above the receiving container  12 . In order to avoid the repeated cleaning of a commonly used valve, one valve device  14  for each base fluid is used herein. The dispensing valve devices  14  preferably are configured in a circular pattern (not shown), although any configuration of dispensing valve devices  14  is possible. Each dispensing valve device  14  includes a supply port for base fluid and preferably a return port for base fluid, as described below. Each dispensing valve device  14  also includes a supply port for pressurized air. Base fluid is supplied to each dispensing valve device  14  from a corresponding supply container  18 . For example, when colored inks are blended, a supply of base liquid ink of a particular color, for instance red, is taken from a supply container  18  by a dedicated pump  16  and pumped to a dedicated dispensing valve device  14  above the receiving container  12 . The ink can be returned to the supply container  18  from the valve device continuously in order to prevent ink from drying in and clogging transfer lines and the dispensing valve device  14 . 
         [0030]    The source of compressed air  20  supplies the pumps  16  and also the dispensing valve devices  14 . Through a solenoid  22 , the compressed air is provided periodically, as required. The air is supplied at different pressures, as required, via a series of regulators  42  or a single, adjustable regulator. 
         [0031]    Computer-based controls  26  manage/change the timing and pressure of air supplied to the dispensing valve devices  14  and the pumps  16 . The computer controls  26  receive input from an operator and also status information, most particularly the weight measured by the scale  24 . The computer controls  26  also receive information regarding the amount of fluids in the supply containers  18  for inventory purposes. The computer controls  26  are programmed with various color mixing recipes within their memory, and with preset routines for distributing compressed air pressure to the pumps  16  and valve devices  14  in order to complete the preparation of such a recipe. The computer controls  26  use input from an operator to specify exact formulas, fluid amounts to be dispensed, and certain operating details. This input may be done at an operator&#39;s station  44  or at a remote computer connected to the computer controls  26 . 
         [0032]    The valve device  14  shown in  FIGS. 2 ,  3 A and  3 B includes a main body  32  that has an end cap  30  threadingly attached to it at a distal end. The distal end cap  30  is cylindrical with a central axial bore  50  therein. A gasket  52  is placed between the distal end cap  30  and the main body  32  to prevent leakage of fluids out of the bottom of the main body  32 . The distal end cap  30  includes an annular seat  51  to receive the gasket  52 . 
         [0033]    The main body  32  is generally cylindrical and hollow. The main body  32  preferably includes at least three fluid ports therein with associated fittings attached to the exterior of the main body  32  at each port. A fluid supply port  54  is located approximately one quarter of the way along the length of the main body  32 , closer to the distal end. Two pipe sections  56  and  58  are provided, connected together in an L-shape with the shorter of the two pipe sections (not shown in  FIG. 3A ) connected to the supply port  54 . A supply of base fluid is provided through these pipe sections and into the main body  32  through the supply port  54 . Two additional pipe sections  60  and  62  are provided, connected together in an L-shape with the shorter of the two pipe sections  60  connected to a return port  64 , located about one third of the way along the length of the main body  32 , closer to the distal end. Base fluid may be returned through these pipes back to a supply container  18 . An air fitting  66  is attached to the third port  68 , located approximately halfway along the length of the main body  32 , and compressed air is introduced into the main body  32  through this fitting  66  and port  68  to move the piston rod  36  in the main body  32 . Axially, the third port  68  is located between the supply and return ports  54  and  64 . Two threaded lateral apertures  70  are located approximately halfway along the length of the main body  32  and extend into its open center. Screws  72  are secured in these apertures  70  and hold a divider  138 , described below. Four lateral apertures  74  in combination with pins  75  are used to facilitate holding the proximal washer  166  in place. 
         [0034]    Referring to  FIGS. 5A and 5B , returning to the distal end cap  30  and the longitudinal bore  50  provided therein, beginning at the distal end and extending toward the proximal end, the bore  50  includes at least two distinct sections  92  and  94  with different diameters. The inner surface  95  of the end cap  30 , defining the first bore section  92  is a contact surface for the seal  114  supported on the piston rod  36 . The first section  92  also has the smallest diameter in the bore  50 . Two countersunk transition sections  98  and  100  are located between the first and second bore sections  92  and  94 . The first transition section  98  has a sidewall  102  with an angle with respect to a longitudinal axis of about 160 degrees. The second transition section  100  is adjacent to the second bore section  94 . The sidewall  104  of the second transition  100  is at an angle of approximately 140 degrees with respect to the longitudinal axis of the valve device  14 . 
         [0035]    Two longitudinal grooves  106  extend from the first bore section  92  to the second bore section  94 . These grooves  106  are generally rectangular and have a sloped distal end  108  that extends from the base of the groove  106  to the wall surface of the first bore section  92 . The sloped distal end  108  is at an angle of between 140-160 degrees to the longitudinal axis of the valve device  14 . This helps prevent damage to the O-ring seal  114  on the piston rod  36  when it moves across the grooves  106 . The distal end of each groove  106  ends about midway along the length of the first bore section  92 . The depth of each groove  106  is approximately 0.03 inches and has a width of approximately 0.04 inches. The grooves  106  are narrow enough to prevent the O-ring seal  114  on the piston rod  36  from fully expanding into and blocking the groove  106 . Thus, if the size of groove  106  is modified, the flexible O-ring seal  114  size is changed accordingly or vise-versa, such that this feature persists. Preferably, the grooves  106  are linear and oriented in a direction parallel to the movement of the piston rod  36 . 
         [0036]    Below the grooves  106  (downstream when considering the direction of fluid movement on discharge from the valve) is simply a smooth portion of a contact surface against which the O-ring seal  114  is compressed when moved by the piston rod past the grooves. When in this position, the O-ring forms a complete seal, so no fluid can pass by. 
         [0037]    The width, depth and number of grooves  106  in the seal contact surface  95  of the end cap  30  determine how much fluid can pass through the valve device  14  when the seal  114  on the piston rod  36  is aligned with the grooves  106 . Edges of the grooves  106  that are on the seal contact surface  95  and that periodically contact the O-ring seal  114  are rounded so that the O-ring seal  114  is not damaged when it moves across the grooves  106 . The second section  94  of the longitudinal bore  50  has a greater diameter than the first section  92 , and the diameter is generally constant. 
         [0038]    Referring to  FIGS. 2 and 3A , the piston rod  36  is elongate and is more narrow at its distal end. The piston rod&#39;s distal end fits into the end cap  30 , as described in more detail below. A first piston portion  110  begins at the distal end and has a constant diameter, except for an annular groove  112  that is within the outer surface of the first piston portion  110  adjacent the distal end. The O-ring seal  114  is seated in this annular groove  112 . A second portion  118  is adjacent to and has a greater diameter than the first portion  110  and has an annular seat the supports an O-ring  143 . An axial bore  126  is placed in the proximal end of the piston rod  36  and this bore  126  is threaded. 
         [0039]    Referring to  FIGS. 2 and 3A , a spring and piston system  38 , including a divider  138 , is used to create three separate chambers  132 ,  134  and  136  within the main body  32  and used to provide desired motion of the components held therein. The cylindrical divider  138  is placed midway along the length of the main body&#39;s interior. This divider  138  is held in place with screws  72  placed through apertures  70  within the side wall of the main body  32 . The divider  138  is cylindrical with an axial bore  140  extending along its entire length. The divider  138  includes a O-ring seal or cup seal  142  contacting the piston rod  36  that passes through the divider&#39;s bore  140  and two O-ring seals  144  on the exterior of the divider  138  contacting the inner wall of the main body  32 . This divider  138  segregates the main body  32  into a first lower chamber  132  for receiving the base fluid and an upper space, part of which receives compressed air. 
         [0040]    A piston/seal  150  is located in the upper space of the main body  34  and is slidable axially therein. The piston/seal  150  includes an annular groove  152  into which a U-cup ring  154  of rubber or another slidable material fits. The ring  154  allows easy sliding movement of the piston/seal  150  in the main body  32 . The piston/seal  150  divides the upper space into the second and third chambers  134  and  136 . 
         [0041]    A cylindrical motion stop  162  is unsecured. The piston/seal  150  uses a screw  160  that secures the piston/seal  150  to the piston rod  36 . The cylindrical motion stop  162  is located within the third chamber  136  between the piston/seal  150  and the proximal end cap  40  and positions a spring  164  therein. A washer  166  is placed between the spring  164  and the proximal end cap  40 . This spring  164  biases the piston/seal  150  downwards. The motion stop  162  stops upward motion of the piston/seal  150  when the stop  162  contacts the washer  166 . 
         [0042]    The improved valve device of the present invention can be used in a similar manner to valves in the prior art in a system previously described in the Background section, with different amounts of air pressure applied thereto to open the valve device  14  different amounts. 
         [0043]    Referring to  FIGS. 2 ,  3 A and  3 B, base fluids are circulated through the valve device  14 , entering at the supply port  54  and exiting at the return port  64 . Compressed air, or another fluid, is supplied at the air fitting  66  at the other supply port  68  of the main body  34 . Compressed air enters into the second chamber  134  and pushes the movable piston/seal  150  upwards, also lifting the piston rod  36  to allow fluid to exit the valve device  14 . 
         [0044]    Air fitting  66  is supplied with air from a three port, two position valve, thus movement into a second position releases air pressure within the valve device  14  while in a first position compressed air can be added to the valve device  14 . 
         [0045]    The valve device  14  is shown in  FIG. 3A  with the piston rod  36  in a closed position. At this time, preferably no fluid is being circulated in the lower chamber  132  of the main body  34 , and the air pressure in the second chamber  134  of the main body is low, thus the piston rod  36  is kept in a lowest position by spring force. Referring to  FIGS. 5A and 5B , when it is desirable to add base fluid to the receiving container placed below the valve device  14 , air pressure is applied to the second chamber  134  of the main body  32 . The piston/seal  150  moves, against spring force, upwards along with the piston rod  36  into a higher position, thus opening a space  170  between the piston rod  36  and seal contact surface  34 . The pump for base fluid being actuated, base fluid flows through this space  170  and into the receiving container (not shown) in a stream. Typically, a pressure of approximately 90 psi is applied to open the piston rod  36  to this position. Approximately, 90%-98% of the required fluid is distributed from the valve device  14  with the piston rod  36  in this position. When approximately 98% of the desired amount of added base fluid is met, the air pressure provided is reduced, thus closing the valve device  14  via spring force of the spring  164 . The air pressure to the valve is then repeatedly pulsed causing the piston rod to move from the position shown in  FIG. 3A  to the intermediate position shown in  FIG. 4A . Depending on the viscosity of the fluid being distributed from the valve device the pumps are either constantly actuated, or not actuated when the piston rod is in the intermediate position, as more viscous fluid requires more pressure to enter the grooves and exit the valve device. Here, fluid can only enter/flow through the grooves  106  within the end cap  30 . Preferably, each pulse of the piston rod  36  allows one drop of fluid to pass into the receiving container. Air pressure is provided at approximately 20-25 psi in order to have the piston rod  36  reach this intermediate position shown in  FIGS. 4A and 4B . The height the piston rod  36  is lifted may be changed by reducing/increasing the pressure of air provided, thus requiring more/less than one pulse to allow a single drop of fluid to pass through the valve device and into the receiving container. If the pressure is increased sufficiently and the viscosity is low engough, a short stream is emitted instead of a single drop on each pulse. For even greater amounts, the pressure may be raised on each pulse such that the piston rod  36  fully exits the first bore section  92 . 
         [0046]    During this pulsing process, on each stroke, fluid is pushed into the grooves by the pressure of the pumps (and gravity) and then out of the grooves and the valve device. In the intermediate position, the seal on the piston rod expands into the grooves only enough to block approximately 20% of the area of the grooves. Thus, the pumps and gravity can still force some fluid through the grooves. The relationship between the pump force and surface tension caused in the grooves determines how much fluid can pass therethough, as well as of course, the viscosity of the fluid being distributed. The frequency of the pulsing of the piston rod (moving between closed and intermediate postions) also determines how much fluid may exit. Typical pulse rates can be 2 pulses per second, but any pulse rate is possible. Increased pressure lifts the piston rod higher in each pulse stroke, and may be so as that the seal of the piston rod is spaced from the seal contact surface. 
         [0047]      FIG. 6  shows an alternative version of a piston rod  80  and end cap  82 . Here, similarly sized linear grooves  84  are placed in the piston rod  80  while a seal  86  is supported on the inner surface  88  of the end cap  82 . In  FIG. 7 , no seal is placed on the piston rod  90 . Close tolerance of the piston rod  90  and end cap  30  provides the required seal function. 
         [0048]    Referring to  FIGS. 8 ,  9 A-B and  11 , in a second embodiment of the invention, an insert  234  fits within the main body  32 , with a distal end portion of the insert  276  pressed into an alternate distal end cap  230 . The insert  234  includes the narrow distal end portion  276  and a wider proximal end portion  278 . The distal end portion  276  is cylindrical and includes an annular groove  280  on its exterior surface. The groove  280  holds the O-ring  282  that seals against an inner surface of the distal end cap bore  250  when the insert  234  is pressed therein. Progressing along the exterior surface of the insert  234  from the distal end portion  276  to the proximal end portion  278 , the surface includes a step from the smaller diameter to the larger diameter proximal end portion  278 . On opposite sides of the proximal portion  276 , two axially extending apertures  284  with rounded ends  286  are provided. These apertures  284  extend laterally into an inner bore of the proximal end portion  278 . Three rectangular grooves  288  extend axially along almost the entire length of the exterior surface of the proximal end portion  278  and are spaced, radially, equal from each other. These grooves align the insert  234  within the main body  32 . A circular transverse aperture  290  passes through the sidewall of the proximal portion  278  near the proximal end as well and extends into a center bore. This aperture provides access for a wrench to tighten a set screw on the piston rod  236 . 
         [0049]    Returning to the distal end portion  276  of the seat device  234 , a longitudinal bore  250  is provided therein, beginning at the distal end and extending toward the proximal end. The bore includes at least three distinct sections  292 ,  294  and  296  with different diameters. The first section  292  has the smallest diameter and is adjacent the distal end of the seat device  234 . Two countersunk transition sections  298  and  300  are located between the first and second bore sections  292  and  294 . The first transition section  298  has a sidewall  302  with a smaller angle with respect to a longitudinal axis of the seat device  234  than the second transition section&#39;s sidewall  304 , the second transition section  300  being adjacent to the second bore section  294 . The sidewall of the second transition  304  is at an angle of approximately 140 degrees with respect to the longitudinal axis of the seat device  234 . 
         [0050]    Two longitudinal grooves  306  extend from the first bore section  292  into the first transition section  298 . These grooves  306  are generally rectangular and have a sloped distal end  308  that extends from the base of the groove  306  to the wall surface of the first bore section  292 . The sloped distal end  308  is at an angle of 160 degrees to the longitudinal axis of the seat device  234 . This helps prevent damage to the O-ring on the piston when it moves across the grooves. The proximal end of each groove  308  ends at about the transition between the first and second countersunk sections  298  and  300 . The distal end of each groove  306  ends about midway along the length of the first bore section  292 . The depth of each groove  306  is approximately 0.03 inches and has a width of approximately 0.04 inches. The grooves  306  are narrow enough to prevent the O-ring  314  from fully expanding into and blocking the groove  306 . Thus, if the size of the O-ring  312  is modified, the size of the groove  306  can be changed accordingly, or vise-versa. 
         [0051]    The depth and number of grooves  306  in the inner surface of the insert  234  determine how much fluid can enter and pass through the valve device  214  when the seal  314  on the piston rod  236  passes over the grooves  306 . Edges of the grooves  306  that are on the surface of the insert  234  that contact the O-ring seal  314  are rounded so that the O-ring seal  314  is not damaged when it moves along the grooves  306 . 
         [0052]    The second section  294  of the longitudinal bore has a greater diameter than the first section  292 . The second section  294  is located between the first section  292  and the third section  296 . The third section  296  has a greater diameter than both the first and second sections of the longitudinal bore, and is constant. The third section  296  of the bore extends to the proximal end of the insert  234 . Three or more wings  299  are spaced equally around the outer surface of the section  278  of the insert  234  and help guide the insert within the main body  32 . 
         [0053]    The surface of first section  292  of the longitudinal bore functions as the contact surface for the seal  314  on the piston rod  236 . Referring to  FIGS. 8 and 9B , the piston rod  236  is elongate and is more narrow at its distal end. The piston rod&#39;s distal end fits into the insert  234 , as described in more detail below. A first piston portion  310  begins at the distal end and has a constant diameter. An annular groove  312  is within the outer surface of the first piston portion  310  adjacent the distal end. An O-ring  314  is seated in this annular groove  312 . A second portion  316 , which is adjacent to the first portion  312  is conical with a diameter which gets larger progressing away from the piston&#39;s distal end. A third portion  318  is adjacent to the second portion  316  and has a diameter greater than both the first and second portions  310  and  316 . The third portion  318  includes a transverse circular bore  320  passing through the full diameter of the piston. A second transverse circular bore  322 , offset 90 degrees from the first transverse bore  320  passes from the exterior surface of the piston into the first bore  320 . The second bore  322  is threaded. A cross pin  323  is inserted through the first bore  320  and extends from each end of the bore  320 . A set screw  325  holds the cross pin  323  in position. A fourth piston portion  324  is adjacent to the third piston portion  318  and extends from the third piston portion  318  to the proximal end of the piston. The fourth portion  324  has a diameter greater than the first and second portions  310  and  316 , but smaller than the third portion  318 . An axial bore  326  is placed in the proximal end of the piston and this bore is threaded. 
         [0054]    Referring to  FIGS. 8 and 9B , a spring and piston system  330  is used to create three separate chambers  332 ,  334  and  336  within the main body  232  and used to provide desired motion of the components held therein. A first cylindrical divider  138  is placed midway along the length of the main body&#39;s interior. This divider  138  is the same as the divider within the first embodiment of the invention. This divider  138  segregates the main body into a first lower chamber  332  for receiving the base fluid and an upper space, part of which receives compressed air. 
         [0055]    A piston/seal  350  is located in the upper space of the main body  234  and is slidable axially therein. The piston/seal  350  includes an annular groove  352  into which a U-cup ring  358  of rubber or another slidable material fits. The ring  358  allows easy sliding movement of the piston/seal  350  in the main body  232 . The piston/seal  350  divides the upper space into the second and third chambers  334  and  336 . 
         [0056]    A spring  356  is located between and abuts the divider  138  and piston/seal  350 . Thus, this spring  356  biases the divider  138  and piston/seal  350  apart. The piston/seal  350  includes an axial bore. A screw  360  passes through this axial bore and secures an O-ring  354  and the piston/seal  350  to the proximal end of the piston rod  236 . Thus, when the piston/seal  350  is biased away from the divider  138 , the piston rod  236  is lifted, and moves out of a sealing position within the insert  234 . 
         [0057]    A cylindrical motion stop  362  is also unsecured. The cylindrical motion stop  362  is located within the third chamber  336  between the piston/seal  350  and the proximal end cap  340  and positions a third spring  364  therein. This spring  364  biases the piston/seal  350  toward the divider  138  and against the spring force of the second spring  356 . 
         [0058]    Again, air pressure is added through the air fitting  66  into chamber  334 . This moves the piston/seal  350  and piston rod  316  upwards.  FIG. 9B  shows the valve device  214  in a closed position.  FIG. 10  shows the valve  214  device in a full open position. The piston rod  236  raises the insert  234  up as well in this highest position, the pin  323  sliding within the aperture  284  until abuts the edge then raising the insert  234  (refer to  FIG. 8 ). Thus, fluid can pass out of the valve device  214  in two ways. Fluid flows past the piston rod  236 , around the seal and also around the exterior of the insert  234  and the seal  282  thereon, thus, a large amount of liquid can be discharged. The grooves  288  within the insert  234  aid in this fast flow. 
         [0059]    The valve device has been described as using compressed air to move the piston rod, thus opening the valve. Any compressed fluid could be used alternatively. Also alternatively, a mechanical system, such as an electric motor linear actuator and associated gears/cams may be used to raise the piston rod instead of an air driven system. The return fluid port is optional, as all fluid within the valve may be dispensed instead of returning fluid to the supply container. Alternatively, any seal that does not fully fill the groove in the seal contact surface can be used instead of O-ring seals. 
         [0060]    In one example of operation of the valve device, which is not limiting other operating speeds, a cycle of movement is from a first position where the seal is against a smooth portion of the seal contact surface to a second position where the seal is against grooves in the seal contact surface and back to first position, and at least 2 cycles are performed per second. 
         [0061]    The valve device and method have been described for use in mixing fluid ink. Other fluids that may be mixed included different paints, or pharmaceutical ingredients. 
         [0062]    This new valve device and method of operation allows fluid to be distributed in a very precise dropwise manner. 
         [0063]    Although the invention has been shown and described with reference to certain preferred and alternate embodiments, the invention is not limited to these specific embodiments. Minor variations and insubstantial differences in the various combinations of materials and methods of application may occur to those of ordinary skill in the art while remaining within the scope of the invention as claimed and equivalents.