Patent Publication Number: US-6981515-B2

Title: Balanced valve body for use with normally-open and normally-closed modes of operation

Description:
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/506,889, filed Sep. 29, 2003, which is incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention relates to a pressure balanced valve for the volumetric control of fluid. More specifically, the present invention relates to a balanced single seated valve which can operate in a normally open mode or a normally closed mode. 
   CROSS-REFERENCE TO RELATED APPLICATIONS 
   The following application covers subject matter related to the present application: U.S. patent application Ser. No. 10/953,980 entitled “Balanced Valve Body for Use with Normally-Open and Normally Closed Modes of Operation” 
   BACKGROUND OF THE INVENTION 
   Control valves typically include a valve plug that is movable toward and away from a valve seat formed in a valve port between a fluid inlet and a fluid outlet. The movement of the valve plug is typically controlled by an actuator. The problem with existing valves is that hydraulic effects are placed on the plug due to pressure differentials in the valve. As a result, larger actuators are required to open or close the valve plug. 
     FIG. 1  shows a conventional two-seated balanced valve. Valve body  10  as shown in  FIG. 1  comprises a pair of seat rings  15 ,  20  to accommodate a pair of valves plugs  25  and  30  to control the flow of liquid between inlet port  35  and outlet port  40 . Valve stem  45 , which is connected to an actuator, not shown, is provided to control the position of the valve plugs  25  and  30 . Valve  10  is further provided with pressure chambers  50  and  55  are provided to balance the pressure of valve plugs  25  and  30  due to the pressure created on the valve plugs as fluid progresses through valve  10  between inlet port  35  and outlet port  40 . The problem with such an arrangement is that in order to minimize leakage, the distance between the valve plugs  25  and  30  and the seat rings  15  and  20  needs to be nearly identical, which is difficult to accomplish. Accordingly, such as balanced valve design is generally given a lower leakage classification. What is needed is a balanced valve design without the leakage problems associated with prior balanced valve designs. Accordingly, there is currently a need to balance the differential pressures in the valve to permit operation of such valves in highest differential pressure applications than is possible with conventional valve and actuator combinations. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a normally-open balanced valve. The balanced valve includes a valve body comprising an inlet port and an outlet port, the valve body further comprising a first side and a second side, the first side and the second side each provided with apertures, where the valve comprises a portion extending between said first side and said second side for dividing the valve into an inlet chamber and an outlet chamber, the valve provided with a plug provided in a position such that an opening between the inlet chamber and the outlet chamber is normally open, the plug having a first side and a second side, said plug provided with a pressure port allowing fluid to flow from said second side of said plug side of said plug to said first side of said plug into a pressure chamber provided in the valve such that fluid flows from the inlet chamber through the port into the pressure chamber to balance the fluid pressure on said plug, and a stem connected to said first side of said plug for moving said plug into a closed position when actuated. 
   In another embodiment, a normally closed balanced valve is provided. The balance valve includes a valve body comprising an inlet port and an outlet port, the valve body further comprising a first side and a second side, the first side and the second side each provided with apertures, the valve comprising a portion extending between the first side and the second side for dividing the valve into an inlet chamber and an outlet chamber such that an opening is provided between the inlet chamber and outlet chamber, the valve provided with a plug provided in a position such that the opening between the inlet chamber and the outlet chamber is normally closed, the plug having a first side and a second side provided with a pressure port allowing fluid to flow from the second side of the plug side of the plug to the first side of the plug into a pressure chamber provided in the valve such that fluid flows from the inlet chamber through the port into the pressure chamber to balance the fluid pressure on the plug, and a stem connected to the second side of the plug. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The aforementioned features, advantages, and aspects of the present invention, will be apparent from the following description and accompanying drawings. Like parts are designated by like reference numbers throughout. 
       FIG. 1 . is a cross-sectional schematic illustration of a conventional two-seated balanced valve; 
       FIG. 2  is a cross-sectional schematic illustration of a normally-open single seated balanced valve in accordance with one aspect of the present invention; 
       FIG. 3  is a cross-sectional schematic illustration of a balanced normally-closed single seated valve in accordance with one aspect of the present invention; 
       FIG. 4  is a flow diagram showing the steps involved in assembling the normally-open single seated vale of  FIG. 2 ; 
       FIG. 5  is a flow diagram showing the steps involved in assembling the normally-closed single seated valve of  FIG. 3 ; 
       FIG. 6  is a flow diagram illustrating the steps in converting the normally open balanced valve of  FIG. 2  to the normally-closed balanced valve of  FIG. 3 ; 
       FIG. 7  is a flow diagram illustrating the steps in converting the normally closed balanced valve of  FIG. 3  to the normally open balanced valve of  FIG. 2 . 
       FIG. 8  cross-sectional schematic illustration of the valve body  10  capable of being used as a three-way valve. 
   

   DETAILED DESCRIPTION 
     FIG. 2  is a cross-sectional illustration of a balanced valve in a normally open position according to the present invention. The illustrated conventional valve  100  is operatively connected to an actuator (not shown). The actuator is typically a powered device that controls the opening and closing of the valve. Valve  100  is comprised of a first body portion  102 , second body portion  104 , and web portions  106  and  108  which extend between the first body portion  102  and the second body portion  104  to divide the valve body  100  into two chambers  110  and  112 . Provided between the web portions  106  and  108  is valve plug seat  114  which is provided to accommodate valve plug  116 . Fluid flowing through valve  100  flows from inlet port  118  through chamber  110  into chamber  112  through the valve plug seat  114  and from the outlet chamber  112  out through outlet port  120 . 
   Valve plug  116  is provided with a first side  122  and a second side  124 . Stem  126  is connected to the first side  122  of valve plug  116 . Packing gland  128  is provided as a seal around valve stem  126 , and also acts as a guide to keep the valve stem  126  from moving laterally within valve body  100 . Packing gland  128  is provided to seal leakage between the valve stem  126  and the bonnet  130 . Gasket  132  is provided between packing gland  128  and bonnet  130 . Bonnet  130  is provided to encapsulate the components within the valve assembly  100 . Bonnet  130  holds therein valve stem  126 , bearing assembly  134 , spring assembly  136  and packing gland  128 . The actuator not shown gets mounted to the bonnet  130  at the top of the bonnet  130 . Bonnet  130 , bearing assembly  134 , spring assembly  136  and packing gland  128  together form bonnet assembly  138  which is located in the aperture  140  of the first body portion  102 . Bonnet  130  is secured to the upper portion  102  of valve body  100  by cap screws  142  extending through bores in the bonnet  130 . Other means such as bolts, slots, combinations thereof, and the like may be used to secure bonnet  40 . Gasket  144  is provided to provide a seal between the bonnet  144  and the valve body  100 . Bearing assembly  134  guides the valve stem  126  and provides lubrication. For exemplary purposes only, the bearing  134  may be a sintered bronze oil-impregnated bearing. Spring assembly  136  provides a biasing pressure against bearing  134 . 
   Connected to the second body portion  104  is cap  146  which is provided to cover aperture  148  in the second body portion  104 . Cap screws  150  are provided to secure the cap  146  to the second body portion  104 . A seal  152  may be provided to prevent leakage between the valve body  104  and the cap  146 . In a preferred embodiment, seal  152  is a O-ring, but various types of sealing devices may be used in place of an O-ring. 
   Plug  116  is guided by plug guide  154  which together with sealing ring  156 , gasket  130  and the first side  122  of plug  116 , provide an upper pressure chamber  158  in the valve body  100 . The purpose of the upper pressure chamber  158  is to provide a container to balance fluid pressure and to also guide the plug  116 . Plug  116  is provided with a pressure port  160  which is the channel through the valve plug  116  which will allow the pressure at the bottom of the plug  116  to enter the upper pressure chamber  158 . Plug  116  accordingly provides two functions in the preferred embodiment: to modulate flow through the inlet port  118  and the outlet port  120 , and to balance the pressure between ports  118  and  120 . The problem with existing control valves is that the inlet pressure in chamber  110  may be higher than the outlet pressure in chamber  112 , which may create unwanted hydraulic effects on plug  116 . According to the present invention, pressure port  160  allows fluid to flow into upper chamber  158 , such that equal pressure is placed upon valve plug  116  to counteract the hydraulic effects on the plug  116  created by differential pressure between the inlet pressure in chamber  110  and the outlet pressure in chamber  112 . 
   In operation, valve stem  126  is operatively connected to an actuator (not shown) that transmits force to move the valve plug  116 . In valve shown in  FIG. 2 , when no actuator force is applied to the valve stem  126 , the valve plug  116  is located such that the valve  100  is in a normally open position. The actuator, which may be provided with fail-safe circuitry, may be used to move the stem  126  such that the valve plug  116  is pressed down against seat ring  114  such that the inlet port  118  and the outlet port  120  are isolated. Anti-rotation pin  162  located in proximity to the seat ring  114  keeps valve plug  116  from rotating. 
     FIG. 3  is a cross-sectional illustration of the balanced valve of the present invention in a normally closed configuration. As shown in  FIG. 3 , cap  246  differs from cap  146  shown in  FIG. 2  in that cap  246  is provided with aperture  248  to secure the stem  126 , and bonnet  130  has been replaced with bonnet  230  which is no longer provided with an aperture so that the bonnet  130  may completed seal off aperture  140  in first body portion  102 . As shown in  FIG. 3 , cap  246  is used to encapsulate the valve stem  126 , bearing assembly  134 , spring assembly  136  and packing gland  128  in the same manner as bonnet  130  in  FIG. 2 . Together these elements comprise cap assembly  250 . 
   Cap  246  is secured to the second body portion  104  of valve body  100  using cap screws  252 . In another embodiment cap  246  may be integral to the valve body  100 . A seal  254  may be provided to prevent leakage between the valve body  100  and the cap  246 . Attached to the first body portion  102  of the valve body  100  is bonnet  230 . Bonnet  230  is secured to the first body portion  102  using screws  256 . Gasket  144  is provided to provide a seal between the bonnet  230  and the first body portion  102 . The plug  116  relative to the valve body  100  is in the same position for normally closed valve as it is for the normally open valve, except the stem is reversed and rotated 180 degrees. 
   Plug  116  is guided by plug guide  154  which together with sealing ring  156  and the first side  122  of plug  116 , provide a lower pressure chamber  260  in the valve body  100 . The purpose of the lower pressure chamber  260  is to provide a container to balance fluid pressure and to also guide the plug  116 . Plug  116  is provided with a pressure port  160  which is the channel through the valve plug  116  which will allow the pressure at the second side of the plug  116  to enter the lower pressure chamber  260 . As was the case with respect to  FIG. 2 , plug  25  shown in  FIG. 3  accordingly provides two functions in the preferred embodiment: to modulate flow through the inlet port  118  and the outlet port  120 , and to balance the pressure between ports  118  and  120 . According to the present invention, pressure port  160  allows fluid to flow into lower chamber  260 , such that balancing pressure is placed upon valve plug  116  to counteract the hydraulic effects on the plug  116  created by differential pressure between inlet pressure of chamber  110  and outlet pressure of chamber  112 . 
   In operation, valve stem  126  is operatively connected to an actuator (not shown) that transmits force to move the valve plug  116 . In valve shown in  FIG. 3 , when no actuator force is applied to the valve stem  126 , the valve plug  116  is located in a normally extended position such that the valve  100  is in a normally closed position. The actuator may be used to move the stem  126  such that the valve plug  116  is raised away from the plug guide  154  so that the valve  100  is in an open position and the chambers  110  and  112  have an open position between them through which fluid may flow. Anti-rotation pin  280  located in proximity to the seat ring  114  keeps valve plug  116  from rotating. 
   Referring now to  FIG. 4 , there is depicted a flowchart, generally designated  400 , of an exemplary manner of operation of the subject invention. This flowchart  400  is described with reference to the assembly of the normally open balanced valve shown in  FIG. 2 . It should be appreciated that the manner of operation depicted in the flowchart  400  of  FIG. 4  is only exemplary of one manner in which the subject invention functions. Other manners, as well as additional steps, less steps, or modified steps constitute valid functioning of the subject invention in accordance with the present principles. 
     FIG. 4  shows a method for manufacturing the normally open balance valve shown in  FIG. 2 . Valve body  100  is provide with aperture  140  through which the valve stem  126  and plug  116  are inserted and which the bonnet  130  closes after being secured to the valve body  100  and is provided with aperture  148  in which the cap assembly  146  will be attached. In the present invention, it does not matter whether the assembly for the first aperture  140  or the second aperture  148  is completed first. Accordingly, while  FIG. 5  shows the bonnet assembly  138  for aperture  140  being assembled first, the cap assembly  146  for aperture  148  may be assembled first. 
   The flowchart  400  begins with step  410 . In step  410 , a valve body  100  is provided with aperture  140  provided in the first portion  102  of the valve  100  and a second smaller aperture  148  in the second portion  104  of the valve body  100 . In step  420 , the stem  126  is attached to the first side  122  of plug  116 . In one embodiment, the stem  126  can be riveted to the first side  122  of plug  116  so that the connection is secure. Before the combined stem  126  and plug  116  are inserted into the aperture  140  of valve  100 , plug guide  154  is inserted into aperture  140  and secured to the first portion  102  of the valve body  100 . In step  430 , once the plug guide  154  is in place, the plug  116 , with stem  126  connected, is inserted through the aperture  140  and is guided into place upon seat ring  114 . 
   In step  440 , after the plug  116  and stem  126  have been inserted into the aperture  140  of valve body  100 , bonnet assembly  130  is secured in place to the valve  100 . Bonnet  130  is first secured in place to the first portion  102  of the valve body  10  using screws  142 . Once bonnet  130  is secured in place, the bonnet  130 , seal  156  and the first side  122  of plug  122  together form pressure chamber  118 . Bonnet  130  is provided with an aperture  131  to accommodate the stem portion  126 . After the bonnet  130  has been secured in place, bearing  134  is then inserted in the aperture  131  of bonnet  130 . Spring  136  is then inserted into the aperture  131  of bonnet  130  to rest upon bearing  134 . Gasket  132  then provided on the upper surface of bonnet  130  and packing gland  128  is inserted into the aperture  131  over the stem  126  so that the bonnet  130  is sealed from the packing gland  128  by gasket  132 . In step  450 , once bonnet assembly  138  has been assembled in place, lower cap assembly  146  may be secured to the second portion  104  of the valve body  100  using screws  150  such that gasket  152  is provided between the cap  146  and second body portion  104 . 
   Referring now to  FIG. 5 , there is depicted a flowchart, generally designated  500 , of an exemplary manner of operation of the subject invention. This flowchart  500  is described with reference to assembly of the normally closed balanced valve  10  of  FIG. 3 . It should be appreciated that the manner of operation depicted in the flowchart  500  of  FIG. 5  is only exemplary of one manner in which the subject invention functions. Other manners, as well as additional steps, less steps, or modified steps constitute valid functioning of the subject invention in accordance with the present principles. 
   The steps for assembling the normally closed balanced valve are similar to the steps for assembling the normally open valve. The fundamental difference is that the stem  126  is connected to the second side  124  of valve plug  116  instead of the first side  122  of the valve plug  116 , so that the stem  126  now extends through aperture  148  instead of aperture  140 . As a result, a different bonnet  230  must be provided that is not provided with an aperture, and a different cap  246  must be provided having an aperture  248  to accommodate the valve stem  126 , the bearing assembly  134 , spring  136  and the packing gland  128 . Valve body  100  is provided with aperture  140  in which the bonnet  130  and valve  116  and stem  126  assembly will be inserted, and is provided with aperture  148  in which the cap assembly  250  will be attached. In the present invention, it does not matter whether the assembly for the first aperture  140  or the second aperture  148  is completed first after the plug  116  and stem  126  have been secured inside the valve body  100 . Accordingly, while  FIG. 6  shows the cap assembly  250  for aperture  148  being assembled first, the bonnet assembly  130  for aperture  140  may be assembled first. 
   The flowchart  500  begins with step  510 . In step  510 , a valve body  100  is provided with aperture  140  provided in the first portion  102  of the valve and a second smaller aperture  148  in the second portion  104  of the valve body  100 . As shown in step  520 , when assembling a normally closed balanced valve, plug guide  154  is inserted into aperture  140  of the first portion  102  of the valve body  100  and is secured in place. In step  530 , stem  126  is then connected to side  124  of plug  116 . In step  540 , the plug  116  and stem  126  are then inserted through aperture  140 . The guide  154  guides the plug  116  and stem  126  assembly in place. Once the stem  126  and plug  116  have been inserted into the valve body  100 , stem portion  126  will extend through aperture  148 . In step  550 , the cap assembly  250  is put together. Cap  246  having an aperture  248  is inserted into aperture  148  so that stem  126  can extend through the aperture  148 . Screws  252  are then used to secure cap  246  to second side  104  of valve body  104 . Once the cap  246  has been secured to the valve body  100 , bearing  134  is then inserted in the aperture  148  of cap  246 . Spring  136  is then inserted into the aperture  248  of cap  246  to rest upon bearing  134 . Gasket  132  is then provided on the upper surface of bonnet  140  and packing gland  128  is inserted into the aperture  248  over the stem  126  so that the cap  246  is sealed from the packing gland  128  by gasket  132 . 
   In step  560 , bonnet  230  may then be secured to the first portion  102  of valve body  100  to seal aperture  140 . Gasket  144  may be provided between the bonnet  230  and the first portion  102  before the bonnet  230  is secured to the first portion  102  using screws  256 . Once the bonnet  230  is secured to the first portion  102 , bonnet  230 , sealing ring  156  and the second side  112  of plug  116  form pressure chamber  260 . 
   Referring now to  FIG. 6 , there is depicted a flowchart, generally designated  600 , of an exemplary manner of operation of the subject invention. This flowchart  700  is described with reference to the conversion of a normally open balanced valve shown in  FIG. 2  to a normally closed balanced valve, shown in  FIG. 3 . It should be appreciated that the manner of assembly depicted in the flowchart  600  of  FIG. 6  is only exemplary of one manner in which the subject invention functions. Other manners, as well as additional steps, less steps, or modified steps constitute valid functioning of the subject invention in accordance with the present principles. 
   The flowchart  600  begins with step  610 . In step  610 , the gasket assembly  138  can be removed from the first portion  102  of the valve body  100 . Next, in step  620 , the stem  126  and plug  116  assembly is removed from the valve body  100  through the aperture  140 . In step  630 , cap portion  146  may then be removed. In step  640 , the stem is removed from the first side  122  of plug  25 , and is then connected to the second side  124  of plug  116 . In step  650 , the valve may then be assembled according to the method shown in  FIG. 5 . 
   Referring now to  FIG. 7 , there is depicted a flowchart, generally designated  700 , of an exemplary manner of operation of the subject invention. This flowchart  700  is described with reference to the conversion of a normally closed balanced valve shown in  FIG. 3  to a normally closed balanced valve, shown in  FIG. 2 . It should be appreciated that the manner of assembly depicted in the flowchart  700  of  FIG. 7  is only exemplary of one manner in which the subject invention functions. Other manners, as well as additional steps, less steps, or modified steps constitute valid functioning of the subject invention in accordance with the present principles. 
   The flowchart  700  begins with step  710 . In step  710 , the cap assembly  250  can be removed from the second portion  104  of the valve body. In step  720 , gasket assembly  230  may then be removed from the first body portion  102  of valve body  10 . In step  730 , the plug  116  and stem  126  assembly may then be removed from the aperture  140  of the first body portion  102 . In step  740 , stem  126  is removed from the second side  124  of plug  116  and then connected to the first side  122  of plug  116 . In step  750 , the valve may then be assembled according to the method shown in  FIG. 4 . 
     FIG. 8  is a cross-sectional illustration of a valve body  10  being used for a three-way valve. The embodiment shown in  FIG. 8  is identical to the embodiment shown in  FIG. 3 , except that plug  816  has been modified from plug  116  and lower seat member  814  has been provided to accommodate the lower portion of plug  816 . Further, bonnet  230  has been removed such that aperture  148  can be used as a second inlet portion so that the valve body  100  can be used as a three way valve. The plug  816  is shown in  FIG. 8  sealing the aperture  140  such that fluid flows from inlet  118  to outlet  120 . However, an actuator can be used to raise plug  816  up into valve body  10  such that fluid flow from inlet  118  is sealed off from outlet  120 , and fluid may flow from aperture  140  to outlet  120 . 
   It will be appreciated that the above described embodiments are merely exemplary and that those of ordinary skill in the art may readily devise their own implementations that incorporate the principles of the present invention and fall within the spirit and scope thereof. For example, the invention is not limited to the exact methods set forth in the  FIG. 3–7  for assembling the normally-open balanced valve and the normally closed balanced valve.