Abstract:
A high pressure three-way control valve comprises a valve body defining first, second, and third ports disposed in selective fluid communication with each other via a control element. The control element is movable between a first seated position and a second seated position to selectively control the direction of fluid between the first and second port, or alternatively, between the first and third port. So configured, the control valve serves a function that conventionally requires two valves plumbed together.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The priority benefit of U.S. Provisional Patent Application No. 60/944,407, filed Jun. 15, 2007 is hereby claimed, and the entire contents thereof are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to air-operated valves, and more particularly, to a high-pressure 3-way air-operated valve. 
     BACKGROUND 
     Plants and factories utilize process control devices to control the flow of fluids in processes, wherein “fluids” may include liquids, gases, or any mixture that can flow through a pipe. Manufacturing processes that create consumer articles or goods such as fuel, food, and clothes require control valves to control and regulate fluid flow. Even a medium sized factory may utilize hundreds of control valves to control a process. Control valves have been utilized for over a century, during which time valve designers have continuously improved the operational performance of control valves. 
     When designing a process, the designer is faced with many design requirements and design constraints. For example, some process control applications require a valve to enable flow in two directions, which are often called bi-directional flow valves. Another example of a design constraint includes the pressure at which the fluid will be operating within the process. For example, some processes operate at relatively low pressures, e.g., less than approximately 10,000 pounds per square inch gauge sig), while other processes may operate at relatively high pressures, e.g., greater than 10,000 psig, and up to approximately 20,000 psig. 
     In certain circumstances, a 2-way or bi-directional valve may not be sufficient to achieve the desired functionality for a selected part of the system. Accordingly, designers wishing to equip a process system with a  3 -way functionality may opt to use two separate two-way or bi-directional valves plumbed together in the same system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan schematic view of a tri-directional or 3-way air-operated control valve in accordance with the present invention and illustrating an exemplary relative location of three ports. 
         FIG. 2  is a cross-sectional side view of one embodiment of the 3-way air-control operated valve taken along line  2 - 2  of  FIG. 1  and assembled in accordance with the present invention and illustrating the control element in a first position. 
         FIG. 3  is another cross-sectional side view of the 3-way air-operated control valve taken along line  3 - 3  of  FIG. 1 . 
         FIG. 4  is a cross-sectional side view similar to  FIG. 2  and illustrating the control element in a second position. 
         FIGS. 5A and 5B  are schematic flow diagrams illustrating a first exemplary flow pattern with the control element in the first and second positions, respectively. 
         FIGS. 6A and 6B  are schematic flow diagrams illustrating a second exemplary flow pattern with the control element in the first and second positions, respectively. 
         FIGS. 7A and 7B  are schematic flow diagrams illustrating a third exemplary flow pattern with the control element in the first and second positions, respectively. 
         FIGS. 8A and 8B  are schematic flow diagrams illustrating a fourth exemplary flow pattern with the control element in the first and second positions, respectively. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1-4 , an air-operated tri-directional or 3-way control valve  10  assembled in accordance with the teachings of the present invention is shown. The control valve  10  generally includes a valve body  12 , first through third ports  14 ,  16 , and  18 , and an actuator assembly  20  for controlling flow through the first through third ports  14 ,  16 , and  18  in a manner to be explained in greater detail below. One example of the relative positions of the ports  14 ,  16 , and  18  is shown schematically in  FIG. 1 . 
     As depicted, the first port  14  is disposed perpendicular to the second port  16 , the second port  16  is disposed perpendicular to the third port  18 , and the first and second ports  14  and  16  are disposed one hundred and eighty degrees from each other. It will be understood that the relative positions of the ports  14 ,  16  and  18  may take any suitable form. The actuator assembly  20  is operated by an air supply source  22  (shown schematically in  FIG. 2 ). The air supply source  22  is connected to a control or air supply port  24 . The actuator assembly  20  includes a control element  26 , which can also be referred to as a thrust pin or control poppet, that is mounted within the valve body  12 . In the disclosed embodiment, the control element  26  is disposed along an axis  1  that is perpendicular to each of the ports  14 ,  16 ,  18 . The control element  26  is adapted for movement or displacement along the axis I between a first position  26 A illustrated in  FIGS. 2 and 3  and a second position  26 B illustrated in  FIG. 4 . 
     The valve body  12  includes an internal bore or throat  28 , which is sized to form a gap or clearance space  30  around the control element  26 . The throat  28  is adapted to be in fluid communication with each of the first through third ports  14 ,  16 ,  18 . As will be explained in greater detail below, the control element  26  moves in response to pressure changes at the air supply port  24 , such that the control element  26  can shift between the first and second positions. 
     The valve body  12  further includes a central portion or base  32  having an upper part  34  and a lower part  36 , with the throat  28  being formed by a bore  38  extending through the base  32 . In the disclosed example, the ports  14 ,  16 , and  18  are formed in the base  32 . More specifically, as shown in  FIGS. 2 and 3 , the first port  14  comprises a generally linear passageway extending through the base  32  of the valve body  12 , while the second and third ports  16 ,  18  include turns. For example, the second port  16  includes a first portion  16   a,  a second portion  16   b,  and a third portion  16   c.  Similarly, the third port  18  includes a first portion  18   a,  a second portion  18   b,  and a third portion  18   c.  In the disclosed embodiment, the second portions  16   b,    18   c  of the second and third ports  16 ,  18  are disposed perpendicular to the first and second portions  16   a,    16   c,    18   a,    18   c.  Alternative embodiments, however, could be constructed differently. 
     The upper part  34  of the base  32  is sized to receive an upper valve insert  40 , while the lower part  36  of the base  32  is sized to receive a lower valve insert  42 . The upper valve insert  40  and the upper part  34  of the base  32  are sized to form an upper chamber  44  in the throat  28 , while the lower valve insert  42  and the lower part  36  of the base  32  are sized to form a lower chamber  46  in the throat  28 . Preferably, the valve inserts  40  and  42  are constructed of  316  stainless steel. The upper chamber  44  is in flow communication with the throat  28  when the control element  26  is in the lowered or second position as shown in  FIG. 4 , while the lower chamber  46  is in flow communication with the throat  28  when the control element  26  is in the raised or first position as shown in  FIGS. 2 and 3 . In the disclosed example, the first port  14  is in fluid communication with the throat  28  via a bore  48 , which as described above is generally linear. The second port  16  is in fluid communication with the upper chamber  44  via a bore  50 , which as described above comprises the first, second, and third portions  16   a,    16   b,    16   c of the second port  16 . Finally, the third port  18  is in fluid communication with the lower chamber  46  via a bore  52 , which as described above includes the first, second, and third portions  18   a,    18   b,    18   c  of the third port  18 . In accordance with the disclosed example, the first port  14  can be brought into selective fluid communication with the second port  16  by placing the control element  26  in the second position of  FIG. 4 , or with the third port  18  by placing the control element  26  in the first position of  FIGS. 2 and 3 . 
     The upper valve insert  40  is secured by an upper cap  54 , while the lower valve insert  42  is secured by a lower cap  56 . Preferably, the upper valve insert  40  includes an outer channel  58  having a seal  60  and a backup ring  62 . Still preferably, the lower valve insert  42  includes an outer channel  64  having a seal  66  and a backup ring  68 . The upper valve insert  40  includes a bore  70  sized to receive an upper portion  72  of the control element  26 . Preferably, the upper portion  72  of the control element  26  includes a channel  74  sized to receive a seal  76  and a backup ring  78 . Similarly, the lower valve insert  42  includes a bore  80  sized to receive a lower portion  82  of the control element  26 . Preferably, the lower portion  82  includes a channel  84  sized to receive a seal  86  and a backup ring  88 . Accordingly, the control element  26  is guided for shiftable sliding movement within the valve body  12  by the bores  70  and  80  in the respective valve inserts. The backup rings preferably include a plastic ring sized and configured to maintain the position of the corresponding seals in the appropriate channels. 
     In addition to the control element  26 , the actuator assembly  20  includes a piston  90  slidably disposed within a piston chamber  92  formed between the upper cap  54  and an upper portion  94  of the upper valve insert  40 . The piston chamber  92  is in flow communication with the air supply port  24 , such that the piston  90  moves within the piston chamber  92  in response to pressure changes in a region  96  above the piston  90 . A lower portion  98  of the piston  90  is coupled to the upper portion  72  of the control element  26  by any suitable coupling. In the disclosed example, an adjustable cap screw  100  disposed in a countersunk hole in the piston  90  secures the piston  90  to the control element. The cap screw  100  may be covered by a removable cover  102 . As spring  91  biases the piston  90  upwardly, which in turn biases the control element  26  toward the first position of  FIGS. 2 and 3 . 
     The control element also includes a central portion  104  having a thickness or diameter which may be widened relative to the thickness or diameters of the upper and lower portions  72  and  82  of the control element  26 . The central portion  104  is bounded on both ends by tapered upper and lower seating surfaces  106  and  108 . The seating surfaces  106  and  108  are tapered, and further are preferably frustoconical. Each of the seating surfaces  106  and  108  transitions into a narrowed portion  110 ,  112 , respectively. The seating surface  106  is sized and positioned to seat against an upper valve seat  114  carried by the base  32  and surrounding a portion of the throat  28 , while the seating surface  108  is sized and positioned to seat against an upper valve seat  116  carried by the base  32  and surrounding a portion of the throat  28 . In the disclosed embodiment, the upper valve seat  114  is disposed between first port  14  and the third portion  16   c of the second port  16 . Additionally, the lower valve seat  116  is disposed between the first port  14  and the third portion  18   c  of the third port  18 . Said another way, the first port  14  communicates with the throat  28  of the valve body  12  at a location between the upper and lower valve seats  114 ,  116 . The second port  16  communicates with the throat  28  at a location opposite the upper valve seat  114  from the first port  14 . The third port  18  communicates with the throat  28  at a location opposite the lower valve seat  116  from the first port  14 . 
     Still referring to  FIGS. 2-4 , the control element  26  includes another tapered portion  107  formed opposite the seating surface  106  on the other side of the narrowed portion  110 . Similarly, the control element  26  includes yet another tapered portion  109  formed opposite the seating surface  108  from the narrowed portion  112 . In accordance with the disclosed example, the exposed area of the seating surface  106  equals the exposed area of the tapered portion  107 . Accordingly, when the control element  26  is in the first position of  FIGS. 2 and 3 , the pressure acting on the equal exposed areas is the same, and therefore the control element  26  is effectively balanced. When the control element  26  is in the second position of  FIG. 4 , once again the exposed area of the seating surface  108  equals the exposed area of the tapered portion  109 . Consequently, the pressure acting on the equal exposed areas is the same. 
     The air supply port  24  preferably is threaded receiving a supply line (not shown) connected to a pneumatic supply. The pneumatic supply may be, for example, a source of compressed shop-air supplied at a pressure of between approximately eighty (80) psig and approximately one-hundred and fifty (150) psig. The force required to move the piston  90  is a function of the surface area of the piston  90 . 
     Based on the foregoing, it will be appreciated that the position of the control element  26  within the control valve  10  can be controlled by introducing compressed air into the piston cavity  92 . For example, in the absence of compressed air supplied to the cavity  92 , the spring  91  biases the piston  90  into the raised first position depicted in  FIGS. 2 and 3 , which causes the seating surface  106  to sealingly engage the valve seat  114 . However, the introduction of compressed air into the region above the piston increases the pressure acting on the top of the piston  90 . When enough pressure is applied to overcome the biasing force of the spring  91 , the piston  90  and hence the control element  26  moves downward from the position shown in  FIGS. 2 and 3  to the position shown in  FIG. 4 . Accordingly, the seating surface  106  moves away from the seat  114 , and the seating surface  108  moves into contact with the seat  116 . 
     It will be appreciated that the ports  14 ,  16 ,  18 , and the above-mentioned chambers and bores are arranged to define a first flow path designated PATH  1  ( FIGS. 2 and 3 ) and a second flow path designated PATH  2  ( FIG. 4 ). As shown in  FIGS. 2 and 3 , PATH  1  extends through the port  14 , the bore  48 , the throat  28 , between the seating surface  108  and the lower valve seat  116  (by virtue of the fact that the control element  26  is in the raised or first position), through the lower chamber  46 , through the bore  52 , and through the port  18 . Accordingly, at least the portions of the first flow path PATH  1  that extend through the ports  14  and  18  are disposed perpendicular to the axis  1  of the control element  26 . As will be explained in greater detail below, depending on which of the ports  14 ,  16 ,  18  are pressurized, fluid may flow in different directions. 
     Next, when the control element  26  is shifted to the lower or second position illustrated in  FIG. 4 , PATH  2  extends through the port  14 , the bore  48 , the throat  28 , between the seating surface  106  and the upper valve seat  114  (by virtue of the fact that the control element  26  is now in the lowered or second position), through the upper chamber  44 , through the bore  50 , and through the port  16 . Accordingly, at least the portions of the second flow path PATH  2  that extend through the ports  14  and  16  are disposed perpendicular to the axis  1  of the control element  26 . 
     In high pressure applications, however, the pressures at one or more of the ports  14 ,  16  or  18  may rise to between approximately 10,000 psig and approximately 20,000 psig. It will be understood that, depending on which of the ports  14 ,  16 ,  18  is under pressure, the pressure will act on one of the tapered seating surfaces  106 ,  108  of the control element  26 , and will urge the control element  26  upward or downward. 
     So configured, the valve  10  of the present invention may be operated with standard compressed shop-air delivered to the region of the piston  90  via the air supply port  24  at a pressure of between approximately eighty (80) psig and one-hundred and fifty (150) psig. Because the diameter of the piston  90  provides a much larger surface area than the exposed surface are of the seating surfaces  106  or  108 , the relatively low-pressure shop air is sufficient to generate sufficient force to overcome the forces of the spring  91  or any upward force caused by fluid pressure in the process system. 
     In accordance with the disclosed example, the control valve  10  may be used in the number of exemplary operational modes. A first exemplary operational mode is illustrated in  FIGS. 5A  (in which the control element  26  is in the first position) and  5 B (in which the control element  26  is in the second position). In  FIG. 5A  the port  14  is pressurized such that pressure flows through the control valve  10  along the first flow path PATH  1  and exits through the port  18 . Port  16  is shut off. When the control element  26  shifts to the second position, pressure flows along PATH  2  from port  14  to port  16 , with port  18  being shut off. 
     A second exemplary operational mode is illustrated in  FIGS. 6A  (in which the control element  26  is in the first position) and  6 B (in which the control element  26  is in the second position). Pressure is supplied to port  16 , and the control valve  10  is effectively closed, as pressure would not flow to the other two ports  14  or  18 . When the control element  26  is shifted to the second position, pressure will flow along the second flow path PATH  2  and flow between ports  16  and  14 . Port  18  is shut off. When the control element  26  returns to the first position, the flow is closed from port  16 , but pressure in port  14  would flow into port  18 . In this case, port  18  is an exhaust port for port  14 . 
     A third exemplary operational mode is illustrated in  FIGS. 7A  (in which the control element  26  is in the first position) and  7 B (in which the control element  26  is in the second position). Pressure is applied to port  18 , such that pressure flows along PATH  1  from port  18  to port  14 . When the control element  26  shifts to the second position, flow is shut off to port  14  from port  18 , but flow is permitted from port  14  two ports  16 . In this situation, port  16  is an exhaust port for port  14 . The examples of FIGS.  6 A,  6 B,  7 A and  7 B are both forms all of fill and dump valves (or exhaust three-way values). Further, the example of  FIGS. 6A and 6B  is a normally closed three-way valve, while the example of  FIGS. 7A and 7B  is a normally open three-way valve. 
     A fourth exemplary operational mode is illustrated in  FIGS. 8A  (in which the control element  26  is in the first position) and  8 B (in which the control element  26  is in the second position). A supply is hooked up to port  16 , and another supply is hooked up to port  18 . When the control element  26  is in the first position, flow goes from port  18  to port  14 . Port  16  is closed. When the control element  26  shifts to the second position, flow goes from port  16  to port  14 . Port  18  is closed. 
     While each of the ports  14 ,  16 ,  18  have been disclosed herein as being perpendicular to the axis  1  of the control element  26 , in alternative embodiments, one or more of the ports  14 ,  16 ,  18  can extend at generally any angle relative to the axis  1  of the control element  26 . 
     While the present disclosure has thus far included a description of a control valve  10  for high-pressure applications, the present valve  10  may also be adapted for use in pressure applications. 
     In light of the foregoing, it should be appreciated that the present detailed description provides merely an example of an air-operated tri-directional control valve constructed in accordance with the principles of the present invention. Variations and modifications, including variations in the materials utilized, that do not depart from the spirit and scope of the present invention are intended to be within the scope of the appended claims.